coding_agent_search/search/

query.rs

use anyhow::{Context, Result, anyhow, bail};
use crossbeam_channel as mpsc;
use frankensearch::lexical::{
    BooleanQuery, CASS_SCHEMA_HASH as FS_CASS_SCHEMA_HASH, CassFields as FsCassFields,
    CassQueryFilters as FsCassQueryFilters, CassQueryToken as FsCassQueryToken,
    CassSourceFilter as FsCassSourceFilter, CassWildcardPattern as FsCassWildcardPattern, Count,
    IndexReader, IndexRecordOption, LexicalDocHit as FsLexicalDocHit,
    LexicalSearchResult as FsLexicalSearchResult, Occur, Query, ReloadPolicy, Searcher,
    SnippetConfig as FsSnippetConfig, TantivyDocument, Term, TermQuery, TopDocs, Value,
    cass_build_tantivy_query as fs_cass_build_tantivy_query,
    cass_has_boolean_operators as fs_cass_has_boolean_operators,
    cass_open_search_reader as fs_cass_open_search_reader,
    cass_parse_boolean_query as fs_cass_parse_boolean_query,
    cass_sanitize_query as fs_cass_sanitize_query, load_doc as fs_load_doc,
    render_snippet_html as fs_render_snippet_html,
    try_build_snippet_generator as fs_try_build_snippet_generator,
};
use frankensearch::{
    Cx as FsCx, InMemoryTwoTierIndex as FsInMemoryTwoTierIndex,
    InMemoryVectorIndex as FsInMemoryVectorIndex, LexicalSearch as FsLexicalSearch,
    QueryClass as FsQueryClass, RrfConfig as FsRrfConfig, ScoreSource as FsScoreSource,
    ScoredResult as FsScoredResult, SearchError as FsSearchError, SearchFuture as FsSearchFuture,
    SearchPhase as FsSearchPhase, SyncEmbedderAdapter as FsSyncEmbedderAdapter,
    SyncTwoTierSearcher as FsSyncTwoTierSearcher, TwoTierConfig as FsTwoTierConfig,
    TwoTierIndex as FsTwoTierIndex, TwoTierSearcher as FsTwoTierSearcher, VectorHit as FsVectorHit,
    candidate_count as fs_candidate_count,
    core::filter::SearchFilter as FsSearchFilter,
    index::{
        HNSW_DEFAULT_EF_SEARCH as FS_HNSW_DEFAULT_EF_SEARCH, HnswIndex as FsHnswIndex,
        VectorIndex as FsVectorIndex,
    },
    rrf_fuse as fs_rrf_fuse,
};
use lru::LruCache;
use once_cell::sync::Lazy;
use parking_lot::RwLock;
use std::cell::RefCell;
use std::cmp::Ordering as CmpOrdering;
use std::collections::{HashMap, HashSet, VecDeque};
use std::hash::{Hash, Hasher};
use std::num::NonZeroUsize;
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicU64, Ordering};
use std::sync::{Arc, Mutex};
use std::time::{Duration, Instant};

use frankensqlite::Connection;
#[cfg(test)]
use frankensqlite::compat::OptionalExtension;
use frankensqlite::compat::{ConnectionExt, ParamValue, RowExt};
#[cfg(test)]
use frankensqlite::params;

/// Wrapper around `frankensqlite::Connection` that implements `Send`.
///
/// `frankensqlite::Connection` is `!Send` because it uses `Rc` internally.
/// However, the `Rc` values are entirely self-contained within the Connection
/// and are not shared with any external references.  When wrapped in a `Mutex`
/// (as in `SearchClient`), exclusive access is guaranteed, making cross-thread
/// transfer safe.
struct SendConnection(Connection);

type TantivyContentExactKey = (i64, i64);
type TantivyContentFallbackKey = (String, String, i64);
type TantivyHydratedContentMaps = (
    HashMap<TantivyContentExactKey, String>,
    HashMap<TantivyContentFallbackKey, String>,
);
type SqliteFtsHydratedRow = (
    i64,
    Option<i64>,
    Option<String>,
    Option<String>,
    Option<String>,
    Option<String>,
    Option<String>,
    Option<i64>,
);
type SqliteFtsMessageRow = (
    i64,
    String,
    String,
    String,
    String,
    String,
    Option<i64>,
    Option<i64>,
    Option<i64>,
    Option<String>,
    Option<String>,
    Option<String>,
);
type SqliteMessageScanAlternative = Vec<String>;
type SqliteMessageScanGroup = Vec<SqliteMessageScanAlternative>;
struct SqliteMessageScanQuery {
    include_groups: Vec<SqliteMessageScanGroup>,
    exclude_terms: Vec<String>,
}

#[derive(Clone, Copy)]
struct SqliteMessageScanRequest<'a> {
    raw_query: &'a str,
    filters: &'a SearchFilters,
    limit: usize,
    offset: usize,
    field_mask: FieldMask,
    query_match_type: MatchType,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
enum SqliteFtsMatchMode {
    Table,
    IndexedColumns,
}

// Frankensqlite follows SQLite's bind-variable ceiling. Keep fallback
// hydration IN-lists below that ceiling so large pages do not turn into
// empty fallback result sets.
const SQLITE_FTS5_HYDRATE_PARAM_CHUNK: usize = 30_000;
const SQLITE_MAX_VARIABLE_NUMBER: usize = 32_766;
const SQLITE_FTS5_POST_FILTER_SCAN_CHUNK: usize = 1_024;
const SQLITE_FTS5_POST_FILTER_SCAN_LIMIT: usize = 30_000;
const SQLITE_MESSAGE_SCAN_FALLBACK_LIMIT: usize = 30_000;
const SEARCH_SQLITE_HYDRATION_CACHE_KIB: i64 = 4_096;
const SEMANTIC_EXACT_CHUNK_OVERFETCH_MULTIPLIER: usize = 4;

// Safety: Rc fields inside Connection are not cloned or shared externally.
// The Mutex<Option<SendConnection>> in SearchClient ensures exclusive access.
unsafe impl Send for SendConnection {}

impl std::ops::Deref for SendConnection {
    type Target = Connection;
    fn deref(&self) -> &Connection {
        &self.0
    }
}

fn open_search_hydration_sqlite(path: &Path, timeout: Duration) -> Result<Connection> {
    let conn =
        crate::storage::sqlite::open_franken_raw_readonly_connection_with_timeout(path, timeout)?;
    conn.execute("PRAGMA query_only = 1;")
        .with_context(|| "setting search hydration query_only")?;
    conn.execute("PRAGMA busy_timeout = 5000;")
        .with_context(|| "setting search hydration busy_timeout")?;
    conn.execute(&format!(
        "PRAGMA cache_size = -{SEARCH_SQLITE_HYDRATION_CACHE_KIB};"
    ))
    .with_context(|| "setting search hydration cache_size")?;
    Ok(conn)
}

/// NFC-normalize a query string before sanitization so that decomposed
/// Unicode (NFD — common on macOS keyboard input) matches NFC-indexed content
/// produced by `DefaultCanonicalizer`.
fn nfc_sanitize_query(raw: &str) -> String {
    use unicode_normalization::UnicodeNormalization;
    let nfc: String = raw.nfc().collect();
    fs_cass_sanitize_query(&nfc)
}

fn franken_query_map_collect_retry<T, F>(
    conn: &Connection,
    sql: &str,
    params: &[ParamValue],
    map: F,
) -> Result<Vec<T>, frankensqlite::FrankenError>
where
    F: Copy + Fn(&frankensqlite::Row) -> Result<T, frankensqlite::FrankenError>,
{
    let deadline = Instant::now() + Duration::from_secs(2);
    let mut backoff = Duration::from_millis(4);
    loop {
        match conn.query_map_collect(sql, params, |row| map(row)) {
            Ok(values) => return Ok(values),
            Err(err) if crate::storage::sqlite::retryable_franken_error(&err) => {
                let now = Instant::now();
                if now >= deadline {
                    return Err(err);
                }
                let remaining = deadline.saturating_duration_since(now);
                crate::storage::sqlite::sleep_with_franken_retry_backoff(
                    &mut backoff,
                    remaining,
                    Duration::from_millis(64),
                );
            }
            Err(err) => return Err(err),
        }
    }
}

fn hydrate_message_content_by_conversation(
    conn: &Connection,
    requests: &[TantivyContentExactKey],
) -> Result<HashMap<TantivyContentExactKey, String>> {
    if requests.is_empty() {
        return Ok(HashMap::new());
    }

    let mut wanted_by_conversation: HashMap<i64, HashSet<i64>> = HashMap::new();
    for &(conversation_id, line_idx) in requests {
        wanted_by_conversation
            .entry(conversation_id)
            .or_default()
            .insert(line_idx);
    }

    let mut conversation_ids = wanted_by_conversation.keys().copied().collect::<Vec<_>>();
    conversation_ids.sort_unstable();
    let mut hydrated = HashMap::with_capacity(requests.len());

    for conversation_id in conversation_ids {
        let Some(wanted_indices) = wanted_by_conversation.get(&conversation_id) else {
            continue;
        };
        let mut wanted_indices = wanted_indices.iter().copied().collect::<Vec<_>>();
        wanted_indices.sort_unstable();
        let placeholders = sql_placeholders(wanted_indices.len());
        let sql = format!(
            "SELECT m.conversation_id, m.idx, m.content
             FROM messages m INDEXED BY sqlite_autoindex_messages_1
             WHERE m.conversation_id = ? AND m.idx IN ({placeholders})
             ORDER BY m.idx"
        );
        let mut params = Vec::with_capacity(wanted_indices.len() + 1);
        params.push(ParamValue::from(conversation_id));
        params.extend(wanted_indices.iter().copied().map(ParamValue::from));
        let rows: Vec<(i64, i64, String)> =
            franken_query_map_collect_retry(conn, &sql, &params, |row| {
                Ok((row.get_typed(0)?, row.get_typed(1)?, row.get_typed(2)?))
            })?;
        for (conversation_id, line_idx, content) in rows {
            hydrated.insert((conversation_id, line_idx), content);
        }
    }

    Ok(hydrated)
}

fn semantic_message_id_from_db(message_id: i64) -> std::io::Result<u64> {
    u64::try_from(message_id).map_err(|_| std::io::Error::other("negative message_id"))
}

fn semantic_doc_component_id_from_db(raw: Option<i64>) -> u32 {
    raw.map(|value| u32::try_from(value.max(0)).unwrap_or(u32::MAX))
        .unwrap_or(0)
}

use crate::search::canonicalize::{canonicalize_for_embedding, content_hash, is_search_noise_text};
use crate::search::embedder::Embedder;
use crate::search::vector_index::{
    ROLE_USER, SemanticDocId, SemanticFilter, SemanticFilterMaps, VectorIndex, VectorSearchResult,
    parse_semantic_doc_id, role_code_from_str,
};
use crate::sources::provenance::SourceFilter;

// ============================================================================
// String Interner for Cache Keys (Opt 2.3)
// ============================================================================
//
// Reduces memory usage and allocation overhead for repeated cache key patterns.
// Uses LRU eviction to bound memory, Arc<str> for cheap cloning.

/// Thread-safe string interner with bounded memory via LRU eviction.
/// Uses LruCache<Arc<str>, Arc<str>> where key and value are the same Arc,
/// enabling O(1) lookup via Borrow<str> trait while preserving LRU semantics.
pub struct StringInterner {
    cache: RwLock<LruCache<Arc<str>, Arc<str>>>,
}

impl StringInterner {
    /// Create a new interner with the given capacity.
    pub fn new(capacity: usize) -> Self {
        Self {
            cache: RwLock::new(LruCache::new(
                NonZeroUsize::new(capacity).expect("capacity must be > 0"),
            )),
        }
    }

    /// Intern a string, returning a shared Arc<str>.
    /// If the string is already interned, returns the existing Arc.
    /// Otherwise, creates a new Arc and caches it.
    ///
    /// Performance: O(1) lookup via LruCache's internal HashMap.
    pub fn intern(&self, s: &str) -> Arc<str> {
        // Fast path: read-only check for existing entry (O(1) lookup)
        {
            let cache = self.cache.read();
            // LruCache::peek allows O(1) lookup without updating LRU order
            // Arc<str>: Borrow<str> enables lookup by &str
            if let Some(arc) = cache.peek(s) {
                return Arc::clone(arc);
            }
        }

        // Slow path: acquire write lock and insert
        let mut cache = self.cache.write();

        // Double-check after acquiring write lock (another thread may have inserted)
        // Use get() here to update LRU order since we're about to use this entry
        if let Some(arc) = cache.get(s) {
            return Arc::clone(arc);
        }

        // Create new Arc<str> and insert (same Arc as key and value)
        let arc: Arc<str> = Arc::from(s);
        cache.put(Arc::clone(&arc), Arc::clone(&arc));
        arc
    }

    /// Get the current number of interned strings.
    #[allow(dead_code)]
    pub fn len(&self) -> usize {
        self.cache.read().len()
    }

    /// Check if the interner is empty.
    #[allow(dead_code)]
    pub fn is_empty(&self) -> bool {
        self.cache.read().is_empty()
    }
}

/// Global cache key interner with 10K entry limit (~1MB for typical keys).
/// Uses Lazy initialization for thread-safe singleton.
static CACHE_KEY_INTERNER: Lazy<StringInterner> = Lazy::new(|| StringInterner::new(10_000));

/// Intern a cache key string, returning a shared Arc<str>.
#[inline]
fn intern_cache_key(s: &str) -> Arc<str> {
    CACHE_KEY_INTERNER.intern(s)
}

// ============================================================================
// SQL Placeholder Builder (Opt 4.5: Pre-sized String Buffers)
// ============================================================================

/// Build a comma-separated list of SQL placeholders with pre-allocated capacity.
///
/// For `n` items, produces "?,?,?..." (n "?" with n-1 ",").
/// Uses pre-sized String to avoid reallocations.
///
/// # Examples
/// ```ignore
/// assert_eq!(sql_placeholders(0), "");
/// assert_eq!(sql_placeholders(1), "?");
/// assert_eq!(sql_placeholders(3), "?,?,?");
/// ```
#[inline]
pub fn sql_placeholders(count: usize) -> String {
    if count == 0 {
        return String::new();
    }
    // Capacity: n "?" + (n-1) "," = 2n - 1
    let capacity = count.saturating_mul(2).saturating_sub(1);
    let mut result = String::with_capacity(capacity);
    for i in 0..count {
        if i > 0 {
            result.push(',');
        }
        result.push('?');
    }
    result
}

#[derive(Debug, Clone, Default, PartialEq, Eq, serde::Serialize)]
pub struct SearchFilters {
    pub agents: HashSet<String>,
    pub workspaces: HashSet<String>,
    pub created_from: Option<i64>,
    pub created_to: Option<i64>,
    /// Filter by conversation source (local, remote, or specific source ID)
    #[serde(skip_serializing_if = "SourceFilter::is_all")]
    pub source_filter: SourceFilter,
    /// Filter to specific session source paths (for chained searches)
    #[serde(skip_serializing_if = "HashSet::is_empty")]
    pub session_paths: HashSet<String>,
}

#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, serde::Serialize, clap::ValueEnum)]
#[serde(rename_all = "snake_case")]
pub enum SearchMode {
    /// Lexical (BM25) search - keyword matching
    Lexical,
    /// Semantic search - embedding similarity
    Semantic,
    /// Hybrid-preferred search - RRF fusion of lexical and semantic when available
    #[default]
    Hybrid,
}

impl SearchMode {
    pub fn next(self) -> Self {
        match self {
            SearchMode::Lexical => SearchMode::Semantic,
            SearchMode::Semantic => SearchMode::Hybrid,
            SearchMode::Hybrid => SearchMode::Lexical,
        }
    }
}

/// Execution strategy for semantic search.
///
/// `Single` preserves existing exact vector behavior.
/// Other modes attempt to use frankensearch's sync two-tier searcher when a
/// compatible in-memory two-tier index is available; otherwise they fall back
/// to `Single`.
#[derive(Debug, Clone, Copy, Default, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum SemanticTierMode {
    #[default]
    Single,
    Progressive,
    FastOnly,
    QualityOnly,
}

impl SemanticTierMode {
    const fn wants_two_tier(self) -> bool {
        !matches!(self, Self::Single)
    }

    fn to_frankensearch_config(self) -> FsTwoTierConfig {
        let mut config = frankensearch_two_tier_config();
        match self {
            Self::Single | Self::Progressive => {}
            Self::FastOnly => {
                config.fast_only = true;
            }
            Self::QualityOnly => {
                config.fast_only = false;
                config.quality_weight = 1.0;
            }
        }
        config
    }
}

const PROGRESSIVE_EMBEDDING_CACHE_CAPACITY: usize = 64;
const ANN_CANDIDATE_MULTIPLIER: usize = 4;
const HYBRID_NO_LIMIT_PLANNING_WINDOW: usize = 64;
const HYBRID_NO_LIMIT_SEMANTIC_CAP: usize = 2048;
const AUTOMATIC_WILDCARD_FALLBACK_MAX_TOKEN_CHARS: usize = 16;

/// Upper bound on how many documents a `limit == 0` ("no limit") search is
/// allowed to materialize. Each `SearchHit` carries the full message
/// `content` string (roughly 80 KB p99 in real corpora), so an unlimited
/// search on a ~500k-row user history can easily allocate tens of
/// gigabytes of heap AND drive sustained multi-GB/s reads off the Tantivy
/// `.store` file and SQLite rows, crushing the whole machine.
///
/// The cap is computed dynamically from `/proc/meminfo` `MemAvailable`
/// (Linux) so a dev box with 512 GB of RAM is allowed to return ~200k
/// rows while a 2 GB laptop stops at the floor. The cap translates
/// directly into an upper bound on disk-I/O per query because the
/// per-hit hydration loop in `fs_load_doc()` / `hydrate_tantivy_hit_contents`
/// does ~11 `.store` field reads per hit plus up to one SQLite row
/// fetch — bounding hits bounds bytes read.
///
/// Override with `CASS_SEARCH_NO_LIMIT_CAP=<hits>` or
/// `CASS_SEARCH_NO_LIMIT_BYTES=<bytes>`. Both overrides are still
/// clamped to `[NO_LIMIT_RESULT_MIN, NO_LIMIT_RESULT_MAX]` on the way
/// out — an unclamped override would re-open the same "crush the
/// machine" hole this cap exists to close.
pub const NO_LIMIT_RESULT_MIN: usize = 1_000;
pub const NO_LIMIT_RESULT_MAX: usize = 1_000_000;

/// Approximate on-heap size per `SearchHit` used to translate a
/// memory budget into a hit-count cap. Kept conservatively high
/// (p99-ish message content + metadata strings) so real workloads
/// stay well under the computed bytes budget.
const AVG_HIT_BYTES: u64 = 80 * 1024;

/// Absolute ceiling on the memory budget for a single "no limit"
/// search, regardless of how much RAM is free. 16 GiB keeps sustained
/// disk reads on a single query bounded to <10 s on a 2 GB/s NVMe —
/// long enough for a power user to wait, short enough not to block
/// other workloads on a shared box.
const NO_LIMIT_BYTES_CEILING: u64 = 16 * 1024 * 1024 * 1024;

/// Floor on the memory budget. On a 2 GB laptop we still let a
/// single "no limit" query use ~256 MiB — small enough to survive,
/// large enough to be useful.
const NO_LIMIT_BYTES_FLOOR: u64 = 256 * 1024 * 1024;

/// Fraction of `MemAvailable` we're willing to spend on a single
/// "no limit" search response. 1/16 leaves 93% of RAM for everything
/// else on the box.
const NO_LIMIT_RAM_DIVISOR: u64 = 16;

fn available_memory_bytes() -> Option<u64> {
    let meminfo = std::fs::read_to_string("/proc/meminfo").ok()?;
    for line in meminfo.lines() {
        if let Some(rest) = line.strip_prefix("MemAvailable:") {
            let kb: u64 = rest.split_whitespace().next()?.parse().ok()?;
            return Some(kb.saturating_mul(1024));
        }
    }
    None
}

fn no_limit_result_cap() -> usize {
    static CAP: std::sync::OnceLock<usize> = std::sync::OnceLock::new();
    *CAP.get_or_init(|| {
        compute_no_limit_result_cap_from(
            std::env::var("CASS_SEARCH_NO_LIMIT_CAP").ok(),
            std::env::var("CASS_SEARCH_NO_LIMIT_BYTES").ok(),
            available_memory_bytes(),
        )
    })
}

/// Pure version of the cap-computation, with env + `/proc/meminfo`
/// passed in as arguments. Kept pure so unit tests can drive it
/// deterministically without mutating the process-global env (which
/// would race with every other parallel test that reads env, including
/// the search-query pipeline tests that transitively hit
/// `no_limit_result_cap()`).
fn compute_no_limit_result_cap_from(
    cap_env: Option<String>,
    bytes_env: Option<String>,
    available_bytes: Option<u64>,
) -> usize {
    // Explicit hit-count override takes priority, but is still clamped
    // to `[MIN, MAX]` so a typo like `CASS_SEARCH_NO_LIMIT_CAP=10000000000`
    // can't reopen the unbounded-result bug this cap closes.
    if let Some(hits) = cap_env
        .and_then(|v| v.parse::<usize>().ok())
        .filter(|v| *v > 0)
    {
        return hits.clamp(NO_LIMIT_RESULT_MIN, NO_LIMIT_RESULT_MAX);
    }

    let budget_bytes = no_limit_budget_bytes(bytes_env, available_bytes);
    let hits = (budget_bytes / AVG_HIT_BYTES) as usize;
    hits.clamp(NO_LIMIT_RESULT_MIN, NO_LIMIT_RESULT_MAX)
}

fn no_limit_budget_bytes(bytes_env: Option<String>, available_bytes: Option<u64>) -> u64 {
    bytes_env
        .and_then(|v| v.parse::<u64>().ok())
        .filter(|v| *v > 0)
        .or_else(|| no_limit_available_memory_budget(available_bytes))
        .unwrap_or(NO_LIMIT_BYTES_FLOOR)
}

fn no_limit_available_memory_budget(available_bytes: Option<u64>) -> Option<u64> {
    available_bytes.map(|avail| {
        (avail / NO_LIMIT_RAM_DIVISOR).clamp(NO_LIMIT_BYTES_FLOOR, NO_LIMIT_BYTES_CEILING)
    })
}

static FRANKENSEARCH_TWO_TIER_CONFIG: Lazy<FsTwoTierConfig> =
    Lazy::new(|| FsTwoTierConfig::optimized().with_env_overrides());

fn frankensearch_two_tier_config() -> FsTwoTierConfig {
    FRANKENSEARCH_TWO_TIER_CONFIG.clone()
}

#[inline]
const fn progressive_phase_fetch_limit(limit: usize) -> usize {
    let limit = if limit == 0 { 1 } else { limit };
    limit.saturating_mul(3)
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
struct HybridCandidateBudget {
    lexical_candidates: usize,
    semantic_candidates: usize,
}

#[inline]
const fn hybrid_stage_multipliers(query_class: FsQueryClass) -> (usize, usize) {
    match query_class {
        // Identifier-heavy queries: prioritize lexical precision.
        FsQueryClass::Identifier => (6, 2),
        // Keyword queries: balanced lexical/semantic retrieval.
        FsQueryClass::ShortKeyword => (4, 4),
        // Natural language queries: prioritize semantic retrieval.
        FsQueryClass::NaturalLanguage => (2, 8),
        // Empty query should short-circuit before budgeting.
        FsQueryClass::Empty => (0, 0),
    }
}

#[inline]
fn hybrid_candidate_budget(
    query: &str,
    requested_limit: usize,
    effective_limit: usize,
    offset: usize,
    total_docs: usize,
) -> HybridCandidateBudget {
    let query_class = FsQueryClass::classify(query);
    let (lex_mult, sem_mult) = hybrid_stage_multipliers(query_class);
    let total_docs = total_docs.max(1);

    // When no explicit limit is requested, keep "no limit" output semantics,
    // but bound semantic fanout so hybrid doesn't try to score the entire corpus.
    if requested_limit == 0 {
        let planning_window = HYBRID_NO_LIMIT_PLANNING_WINDOW.max(offset.saturating_add(1));
        // Cap the lexical fanout — without a ceiling a "no limit" hybrid
        // query on a ~500k-row corpus asks Tantivy to materialize a
        // `Vec<SearchHit>` the size of the entire index, which is the
        // unboundedness fixed by `no_limit_result_cap()`.
        let lexical = effective_limit.min(total_docs).min(no_limit_result_cap());
        // Semantic fan-out can be wide in principle, but must never
        // exceed the lexical cap — the pipeline fuses lexical+semantic
        // candidates and returning more semantic candidates than
        // lexical is both wasteful (semantic is the expensive tier)
        // and breaks the pre-cap invariant that `semantic ≤ lexical`.
        // On tiny boxes where `no_limit_result_cap()` hits the floor,
        // this pulls semantic down with it.
        let semantic = fs_candidate_count(planning_window, 0, sem_mult)
            .max(planning_window)
            .min(HYBRID_NO_LIMIT_SEMANTIC_CAP.max(offset.saturating_add(planning_window)))
            .min(total_docs)
            .min(lexical);
        return HybridCandidateBudget {
            lexical_candidates: lexical,
            semantic_candidates: semantic,
        };
    }

    let lexical = fs_candidate_count(requested_limit, offset, lex_mult.max(1))
        .max(requested_limit.saturating_add(offset))
        .min(total_docs);
    let semantic = fs_candidate_count(requested_limit, offset, sem_mult.max(1))
        .max(requested_limit.saturating_add(offset))
        .min(total_docs);

    HybridCandidateBudget {
        lexical_candidates: lexical,
        semantic_candidates: semantic,
    }
}

// ============================================================================
// Query Explanation types (--explain flag support)
// ============================================================================

/// Classification of query type for explanation purposes
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum QueryType {
    /// Single term without operators
    Simple,
    /// Quoted phrase ("exact match")
    Phrase,
    /// Contains AND/OR/NOT operators
    Boolean,
    /// Contains wildcards (* prefix/suffix)
    Wildcard,
    /// Has time/agent/workspace filters
    Filtered,
    /// Empty query
    Empty,
}

/// How the index will execute this query
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum IndexStrategy {
    /// Fast path: edge n-gram prefix matching
    EdgeNgram,
    /// Regex scan for leading wildcards (*foo)
    RegexScan,
    /// Combined boolean query execution
    BooleanCombination,
    /// Range scan for time filters
    RangeScan,
    /// All documents (empty query)
    FullScan,
}

/// Rough complexity indicator for query execution
#[derive(Debug, Clone, Copy, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum QueryCost {
    /// Very fast (under 10ms typical)
    Low,
    /// Moderate (10-100ms typical)
    Medium,
    /// Expensive (100ms+ typical, may scan many documents)
    High,
}

/// Sub-component of a parsed term
#[derive(Debug, Clone, serde::Serialize)]
pub struct ParsedSubTerm {
    pub text: String,
    pub pattern: String,
}

/// Parsed term from the query
#[derive(Debug, Clone, serde::Serialize)]
pub struct ParsedTerm {
    /// Original term text
    pub text: String,
    /// Whether this is negated (NOT/-)
    pub negated: bool,
    /// Sub-terms if split (implicit AND)
    pub subterms: Vec<ParsedSubTerm>,
}

/// Parsed structure of the query
#[derive(Debug, Clone, Default, serde::Serialize)]
pub struct ParsedQuery {
    /// Individual terms extracted
    pub terms: Vec<ParsedTerm>,
    /// Phrases (quoted strings)
    pub phrases: Vec<String>,
    /// Boolean operators used
    pub operators: Vec<String>,
    /// Whether implicit AND is used between terms
    pub implicit_and: bool,
}

/// Comprehensive query explanation for debugging and understanding search behavior
#[derive(Debug, Clone, serde::Serialize)]
pub struct QueryExplanation {
    /// Exact input string
    pub original_query: String,
    /// Sanitized query after normalization
    pub sanitized_query: String,
    /// Structured breakdown of query components
    pub parsed: ParsedQuery,
    /// High-level classification
    pub query_type: QueryType,
    /// How the index will execute this query
    pub index_strategy: IndexStrategy,
    /// Whether wildcard fallback was/will be applied
    pub wildcard_applied: bool,
    /// Rough complexity indicator
    pub estimated_cost: QueryCost,
    /// Active filters summary
    pub filters_summary: FiltersSummary,
    /// Any issues or suggestions
    pub warnings: Vec<String>,
}

/// Summary of active filters for explanation
#[derive(Debug, Clone, Default, serde::Serialize)]
pub struct FiltersSummary {
    /// Number of agent filters
    pub agent_count: usize,
    /// Number of workspace filters
    pub workspace_count: usize,
    /// Whether time range is applied
    pub has_time_filter: bool,
    /// Human-readable filter description
    pub description: Option<String>,
}

impl QueryExplanation {
    /// Build explanation from query string and filters
    pub fn analyze(query: &str, filters: &SearchFilters) -> Self {
        let sanitized = nfc_sanitize_query(query);
        // Parse original query to preserve quotes for phrases
        let tokens = fs_cass_parse_boolean_query(query);

        // Extract terms, phrases, and operators
        let mut parsed = ParsedQuery::default();
        let mut has_explicit_operator = false;
        let mut next_negated = false;

        for token in &tokens {
            match token {
                FsCassQueryToken::Term(t) => {
                    let parts: Vec<String> = nfc_sanitize_query(t)
                        .split_whitespace()
                        .map(|s| s.to_string())
                        .collect();
                    if parts.is_empty() {
                        next_negated = false;
                        continue;
                    }
                    let mut subterms = Vec::new();
                    for part in parts {
                        let pattern = FsCassWildcardPattern::parse(&part);
                        let pattern_str = match &pattern {
                            FsCassWildcardPattern::Exact(_) => "exact",
                            FsCassWildcardPattern::Prefix(_) => "prefix (*)",
                            FsCassWildcardPattern::Suffix(_) => "suffix (*)",
                            FsCassWildcardPattern::Substring(_) => "substring (*)",
                            FsCassWildcardPattern::Complex(_) => "complex (*)",
                        };
                        subterms.push(ParsedSubTerm {
                            text: part,
                            pattern: pattern_str.to_string(),
                        });
                    }
                    parsed.terms.push(ParsedTerm {
                        text: t.clone(),
                        negated: next_negated,
                        subterms,
                    });
                    next_negated = false;
                }
                FsCassQueryToken::Phrase(p) => {
                    let parts: Vec<String> = nfc_sanitize_query(p)
                        .split_whitespace()
                        .map(|s| s.trim_matches('*').to_lowercase())
                        .filter(|s| !s.is_empty())
                        .collect();
                    if !parts.is_empty() {
                        parsed.phrases.push(parts.join(" "));
                    }
                    next_negated = false;
                }
                FsCassQueryToken::And => {
                    parsed.operators.push("AND".to_string());
                    has_explicit_operator = true;
                }
                FsCassQueryToken::Or => {
                    parsed.operators.push("OR".to_string());
                    has_explicit_operator = true;
                }
                FsCassQueryToken::Not => {
                    parsed.operators.push("NOT".to_string());
                    has_explicit_operator = true;
                    next_negated = true;
                }
            }
        }

        // Implicit AND between terms if no explicit operators
        parsed.implicit_and = !has_explicit_operator && parsed.terms.len() > 1;

        // Determine query type
        let query_type = Self::classify_query(&parsed, filters, &sanitized);

        // Determine index strategy
        let index_strategy = Self::determine_strategy(&parsed, &sanitized);

        // Estimate cost
        let estimated_cost = Self::estimate_cost(&parsed, &index_strategy, filters);

        // Build filters summary
        let filters_summary = Self::summarize_filters(filters);

        // Generate warnings
        let warnings = Self::generate_warnings(&parsed, &sanitized, filters);

        Self {
            original_query: query.to_string(),
            sanitized_query: sanitized,
            parsed,
            query_type,
            index_strategy,
            wildcard_applied: false, // Set later by search_with_fallback
            estimated_cost,
            filters_summary,
            warnings,
        }
    }

    fn classify_query(parsed: &ParsedQuery, filters: &SearchFilters, sanitized: &str) -> QueryType {
        if sanitized.trim().is_empty() {
            return QueryType::Empty;
        }

        // Check for filters first (they modify everything)
        let has_filters = !filters.agents.is_empty()
            || !filters.workspaces.is_empty()
            || filters.created_from.is_some()
            || filters.created_to.is_some()
            || !filters.source_filter.is_all();

        if has_filters {
            return QueryType::Filtered;
        }

        // Check for boolean operators
        if !parsed.operators.is_empty() {
            return QueryType::Boolean;
        }

        // Check for phrases
        if !parsed.phrases.is_empty() {
            return QueryType::Phrase;
        }

        // Check for wildcards
        let has_wildcards = parsed
            .terms
            .iter()
            .flat_map(|t| &t.subterms)
            .any(|t| t.pattern != "exact");
        if has_wildcards {
            return QueryType::Wildcard;
        }

        QueryType::Simple
    }

    fn determine_strategy(parsed: &ParsedQuery, sanitized: &str) -> IndexStrategy {
        if sanitized.trim().is_empty() {
            return IndexStrategy::FullScan;
        }

        // Check for leading wildcards (requires regex)
        let has_leading_wildcard = parsed
            .terms
            .iter()
            .flat_map(|t| &t.subterms)
            .any(|t| t.pattern == "suffix (*)" || t.pattern == "substring (*)");

        if has_leading_wildcard {
            return IndexStrategy::RegexScan;
        }

        // Boolean queries use combination strategy
        // Also if any single term is split into multiple subterms (e.g. "foo.bar" -> "foo", "bar")
        let has_compound_terms = parsed.terms.iter().any(|t| t.subterms.len() > 1);

        if !parsed.operators.is_empty()
            || parsed.terms.len() > 1
            || !parsed.phrases.is_empty()
            || has_compound_terms
        {
            return IndexStrategy::BooleanCombination;
        }

        // Single term uses edge n-gram
        IndexStrategy::EdgeNgram
    }

    fn estimate_cost(
        parsed: &ParsedQuery,
        strategy: &IndexStrategy,
        filters: &SearchFilters,
    ) -> QueryCost {
        // Regex scans are always expensive
        if matches!(strategy, IndexStrategy::RegexScan) {
            return QueryCost::High;
        }

        // Full scans are expensive
        if matches!(strategy, IndexStrategy::FullScan) {
            return QueryCost::High;
        }

        // Time range filters add cost
        let has_time_filter = filters.created_from.is_some() || filters.created_to.is_some();

        // Count complexity factors
        let term_count: usize = parsed.terms.iter().map(|t| t.subterms.len()).sum();
        let operator_count = parsed.operators.len();
        let phrase_count = parsed.phrases.len();

        let complexity = term_count + operator_count * 2 + phrase_count * 2;

        if complexity > 6 || has_time_filter {
            QueryCost::High
        } else if complexity > 2 {
            QueryCost::Medium
        } else {
            QueryCost::Low
        }
    }

    fn summarize_filters(filters: &SearchFilters) -> FiltersSummary {
        let agent_count = filters.agents.len();
        let workspace_count = filters.workspaces.len();
        let has_time_filter = filters.created_from.is_some() || filters.created_to.is_some();

        let mut parts = Vec::new();
        if agent_count > 0 {
            parts.push(format!(
                "{} agent{}",
                agent_count,
                if agent_count > 1 { "s" } else { "" }
            ));
        }
        if workspace_count > 0 {
            parts.push(format!(
                "{} workspace{}",
                workspace_count,
                if workspace_count > 1 { "s" } else { "" }
            ));
        }
        if has_time_filter {
            parts.push("time range".to_string());
        }

        let description = if parts.is_empty() {
            None
        } else {
            Some(format!("Filtering by: {}", parts.join(", ")))
        };

        FiltersSummary {
            agent_count,
            workspace_count,
            has_time_filter,
            description,
        }
    }

    fn generate_warnings(
        parsed: &ParsedQuery,
        sanitized: &str,
        filters: &SearchFilters,
    ) -> Vec<String> {
        let mut warnings = Vec::new();

        // Warn about leading wildcards
        let has_leading_wildcard = parsed
            .terms
            .iter()
            .flat_map(|t| &t.subterms)
            .any(|t| t.pattern == "suffix (*)" || t.pattern == "substring (*)");
        if has_leading_wildcard {
            warnings.push(
                "Leading wildcards (*foo) require regex scan and may be slow on large indexes"
                    .to_string(),
            );
        }

        // Warn about very short terms
        for term in &parsed.terms {
            for sub in &term.subterms {
                if sub.text.trim_matches('*').len() < 2 {
                    warnings.push(format!(
                        "Very short term '{}' may match many documents",
                        sub.text
                    ));
                }
            }
        }

        // Warn about empty query
        if sanitized.trim().is_empty() {
            warnings.push("Empty query will return all documents (expensive)".to_string());
        }

        // Warn about complex boolean queries
        if parsed.operators.len() > 3 {
            warnings.push("Complex boolean query may have unexpected precedence".to_string());
        }

        // Warn about narrow filters that might miss results
        if let Some(agent) = filters.agents.iter().next()
            && filters.agents.len() == 1
            && filters.workspaces.is_empty()
        {
            warnings.push(format!(
                "Searching only in agent '{}' - results from other agents will be excluded",
                agent
            ));
        }

        warnings
    }

    /// Update `wildcard_applied` flag (called after `search_with_fallback`)
    pub fn with_wildcard_fallback(mut self, applied: bool) -> Self {
        self.wildcard_applied = applied;
        if applied
            && !self
                .warnings
                .iter()
                .any(|w| w.contains("wildcard fallback"))
        {
            self.warnings.push(
                "Wildcard fallback was applied automatically due to sparse exact matches"
                    .to_string(),
            );
        }
        self
    }
}

/// Indicates how a search result matched the query.
/// Used for ranking: exact matches rank higher than wildcard matches.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum MatchType {
    /// No wildcards - matched via exact term or edge n-gram prefix
    #[default]
    Exact,
    /// Matched via trailing wildcard (foo*)
    Prefix,
    /// Matched via leading wildcard (*foo) - uses regex
    Suffix,
    /// Matched via both wildcards (*foo*) - uses regex
    Substring,
    /// Matched via complex wildcard (e.g. f*o) - uses regex
    Wildcard,
    /// Matched via automatic wildcard fallback when exact search was sparse
    ImplicitWildcard,
}

impl MatchType {
    /// Returns a quality factor for ranking (1.0 = best, lower = less precise match)
    pub fn quality_factor(self) -> f32 {
        match self {
            MatchType::Exact => 1.0,
            MatchType::Prefix => 0.9,
            MatchType::Suffix => 0.8,
            MatchType::Substring => 0.7,
            MatchType::Wildcard => 0.65,
            MatchType::ImplicitWildcard => 0.6,
        }
    }
}

/// Type of suggestion for did-you-mean
#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize)]
#[serde(rename_all = "snake_case")]
pub enum SuggestionKind {
    /// Typo correction (Levenshtein distance)
    SpellingFix,
    /// Try with wildcard prefix/suffix
    WildcardQuery,
    /// Remove restrictive filter
    RemoveFilter,
    /// Try different agent
    AlternateAgent,
    /// Broaden date range
    BroaderDateRange,
}

/// A "did-you-mean" suggestion when search returns zero hits.
#[derive(Debug, Clone, serde::Serialize)]
pub struct QuerySuggestion {
    /// What kind of suggestion this is
    pub kind: SuggestionKind,
    /// Human-readable description (e.g., "Did you mean: 'codex'?")
    pub message: String,
    /// The suggested query string (if query change)
    pub suggested_query: Option<String>,
    /// Suggested filters to apply (replaces current filters if Some)
    pub suggested_filters: Option<SearchFilters>,
    /// Shortcut key (1, 2, or 3) for quick apply in TUI
    pub shortcut: Option<u8>,
}

impl QuerySuggestion {
    fn spelling(_query: &str, corrected: &str) -> Self {
        Self {
            kind: SuggestionKind::SpellingFix,
            message: format!("Did you mean: \"{corrected}\"?"),
            suggested_query: Some(corrected.to_string()),
            suggested_filters: None,
            shortcut: None,
        }
    }

    fn wildcard(query: &str) -> Self {
        let wildcard_query = format!("*{}*", query.trim_matches('*'));
        Self {
            kind: SuggestionKind::WildcardQuery,
            message: format!("Try broader search: \"{wildcard_query}\""),
            suggested_query: Some(wildcard_query),
            suggested_filters: None,
            shortcut: None,
        }
    }

    fn remove_agent_filter(current_agent: &str, current_filters: &SearchFilters) -> Self {
        // Clone current filters and only clear the agent filter, preserving
        // workspace and date range filters
        let mut filters = current_filters.clone();
        filters.agents.clear();
        Self {
            kind: SuggestionKind::RemoveFilter,
            message: format!("Remove agent filter (currently: {current_agent})"),
            suggested_query: None,
            suggested_filters: Some(filters),
            shortcut: None,
        }
    }

    fn try_agent(agent_slug: &str) -> Self {
        let mut filters = SearchFilters::default();
        filters.agents.insert(agent_slug.to_string());
        Self {
            kind: SuggestionKind::AlternateAgent,
            message: format!("Try searching in: {agent_slug}"),
            suggested_query: None,
            suggested_filters: Some(filters),
            shortcut: None,
        }
    }

    fn with_shortcut(mut self, key: u8) -> Self {
        self.shortcut = Some(key);
        self
    }
}

#[derive(Debug, Clone, Copy)]
pub struct FieldMask {
    flags: u8,
    preview_content_chars: Option<usize>,
}

impl FieldMask {
    const CONTENT: u8 = 1 << 0;
    const SNIPPET: u8 = 1 << 1;
    const TITLE: u8 = 1 << 2;
    const CACHE: u8 = 1 << 3;

    pub const FULL: Self = Self {
        flags: Self::CONTENT | Self::SNIPPET | Self::TITLE | Self::CACHE,
        preview_content_chars: None,
    };

    pub fn new(
        wants_content: bool,
        wants_snippet: bool,
        wants_title: bool,
        allows_cache: bool,
    ) -> Self {
        let mut flags = 0;
        if wants_content {
            flags |= Self::CONTENT;
        }
        if wants_snippet {
            flags |= Self::SNIPPET;
        }
        if wants_title {
            flags |= Self::TITLE;
        }
        if allows_cache {
            flags |= Self::CACHE;
        }
        Self {
            flags,
            preview_content_chars: None,
        }
    }

    pub fn with_preview_content_limit(mut self, max_chars: Option<usize>) -> Self {
        self.preview_content_chars = max_chars;
        if max_chars.is_some() {
            self.flags &= !Self::CACHE;
        }
        self
    }

    pub fn needs_content(self) -> bool {
        self.flags & Self::CONTENT != 0
    }

    pub fn wants_snippet(self) -> bool {
        self.flags & Self::SNIPPET != 0
    }

    pub fn wants_title(self) -> bool {
        self.flags & Self::TITLE != 0
    }

    pub fn allows_cache(self) -> bool {
        self.flags & Self::CACHE != 0
    }

    pub fn preview_content_limit(self) -> Option<usize> {
        self.preview_content_chars
    }
}

#[derive(Debug, Clone, serde::Serialize)]
pub struct SearchHit {
    pub title: String,
    pub snippet: String,
    pub content: String,
    #[serde(skip_serializing)]
    pub content_hash: u64,
    #[serde(skip_serializing)]
    pub conversation_id: Option<i64>,
    pub score: f32,
    pub source_path: String,
    pub agent: String,
    pub workspace: String,
    /// Original workspace path before rewriting (P6.2)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub workspace_original: Option<String>,
    pub created_at: Option<i64>,
    /// Line number in the source file where the matched message starts (1-indexed)
    pub line_number: Option<usize>,
    /// How this result matched the query (exact, prefix wildcard, etc.)
    #[serde(default)]
    pub match_type: MatchType,
    // Provenance fields (P3.3)
    /// Source identifier (e.g., "local", "work-laptop")
    #[serde(default = "default_source_id")]
    pub source_id: String,
    /// Origin kind ("local" or "ssh")
    #[serde(default = "default_source_id")]
    pub origin_kind: String,
    /// Origin host label for remote sources
    #[serde(skip_serializing_if = "Option::is_none")]
    pub origin_host: Option<String>,
}

static LAZY_FIELDS_ENABLED: Lazy<bool> = Lazy::new(|| {
    dotenvy::var("CASS_LAZY_FIELDS")
        .ok()
        .map(|v| !(v == "0" || v.eq_ignore_ascii_case("false")))
        .unwrap_or(true)
});

fn default_source_id() -> String {
    "local".to_string()
}

fn effective_field_mask(field_mask: FieldMask) -> FieldMask {
    if *LAZY_FIELDS_ENABLED {
        field_mask
    } else {
        FieldMask::FULL
    }
}

fn execute_query_with_lazy_exact_count(
    searcher: &Searcher,
    query: &dyn Query,
    limit: usize,
    offset: usize,
) -> Result<FsLexicalSearchResult> {
    let top_docs = searcher.search(
        query,
        &TopDocs::with_limit(limit)
            .and_offset(offset)
            .order_by_score(),
    )?;
    let page_saturated = top_docs.len() == limit;
    let total_count = if page_saturated {
        searcher.search(query, &Count)?
    } else {
        offset.saturating_add(top_docs.len())
    };
    let hits = top_docs
        .into_iter()
        .enumerate()
        .map(|(rank, (bm25_score, doc_address))| FsLexicalDocHit {
            bm25_score,
            rank,
            doc_address,
        })
        .collect();

    Ok(FsLexicalSearchResult { hits, total_count })
}

/// Result of a search operation with metadata about how matches were found
#[derive(Debug, Clone)]
pub struct SearchResult {
    /// The search results
    pub hits: Vec<SearchHit>,
    /// Whether wildcard fallback was used (query had no/few exact matches)
    pub wildcard_fallback: bool,
    /// Cache metrics snapshot for observability/debug
    pub cache_stats: CacheStats,
    /// Did-you-mean suggestions when hits are empty or sparse
    pub suggestions: Vec<QuerySuggestion>,
    /// ANN search statistics (present when --approximate was used)
    pub ann_stats: Option<crate::search::ann_index::AnnSearchStats>,
    /// True total matching documents from the search engine (when available).
    /// For lexical searches this comes from Tantivy's `Count` collector and
    /// reflects the total number of documents matching the query, independent
    /// of limit/offset pagination. `None` for semantic/hybrid/cached paths
    /// where the true total is unknown.
    pub total_count: Option<usize>,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ProgressivePhaseKind {
    Initial,
    Refined,
}

// Phase events intentionally carry a complete SearchResult so consumers can
// react without reloading auxiliary state or keeping cross-event caches.
#[allow(clippy::large_enum_variant)]
#[derive(Debug, Clone)]
pub enum ProgressiveSearchEvent {
    Phase {
        kind: ProgressivePhaseKind,
        result: SearchResult,
        elapsed_ms: u128,
    },
    RefinementFailed {
        latency_ms: u128,
        error: String,
    },
}

#[derive(Debug, Clone)]
pub(crate) struct ProgressiveSearchRequest<'a> {
    pub(crate) cx: &'a FsCx,
    pub(crate) query: &'a str,
    pub(crate) filters: SearchFilters,
    pub(crate) limit: usize,
    pub(crate) sparse_threshold: usize,
    pub(crate) field_mask: FieldMask,
    pub(crate) mode: SearchMode,
}

#[derive(Debug, Clone, PartialEq, Eq, Hash)]
struct SearchHitKey {
    source_id: String,
    source_path: String,
    conversation_id: Option<i64>,
    title: String,
    line_number: Option<usize>,
    created_at: Option<i64>,
    content_hash: u64,
}

fn normalized_search_source_id_sql_expr(
    source_id_column: &str,
    origin_kind_column: &str,
    origin_host_column: &str,
) -> String {
    format!(
        "CASE \
            WHEN TRIM(COALESCE({source_id_column}, '')) != '' THEN \
                CASE \
                    WHEN LOWER(TRIM(COALESCE({source_id_column}, ''))) = '{local}' THEN '{local}' \
                    ELSE TRIM(COALESCE({source_id_column}, '')) \
                END \
            WHEN LOWER(TRIM(COALESCE({origin_kind_column}, ''))) IN ('ssh', 'remote') THEN \
                CASE \
                    WHEN TRIM(COALESCE({origin_host_column}, '')) = '' THEN 'remote' \
                    ELSE TRIM(COALESCE({origin_host_column}, '')) \
                END \
            WHEN LOWER(TRIM(COALESCE({origin_kind_column}, ''))) = '{local}' THEN '{local}' \
            WHEN TRIM(COALESCE({origin_host_column}, '')) != '' THEN TRIM(COALESCE({origin_host_column}, '')) \
            ELSE '{local}' \
         END",
        local = crate::sources::provenance::LOCAL_SOURCE_ID,
    )
}

fn normalize_search_source_filter_value(source_id: &str) -> String {
    let trimmed = source_id.trim();
    if trimmed.eq_ignore_ascii_case(crate::sources::provenance::LOCAL_SOURCE_ID) {
        crate::sources::provenance::LOCAL_SOURCE_ID.to_string()
    } else {
        trimmed.to_string()
    }
}

fn normalized_search_hit_source_id_parts(
    source_id: &str,
    origin_kind: &str,
    origin_host: Option<&str>,
) -> String {
    let trimmed_source_id = source_id.trim();
    if !trimmed_source_id.is_empty() {
        if trimmed_source_id.eq_ignore_ascii_case(crate::sources::provenance::LOCAL_SOURCE_ID) {
            return crate::sources::provenance::LOCAL_SOURCE_ID.to_string();
        }
        return trimmed_source_id.to_string();
    }

    let trimmed_origin_host = origin_host.map(str::trim).filter(|value| !value.is_empty());
    let trimmed_origin_kind = origin_kind.trim();
    if trimmed_origin_kind.eq_ignore_ascii_case("ssh")
        || trimmed_origin_kind.eq_ignore_ascii_case("remote")
    {
        return trimmed_origin_host.unwrap_or("remote").to_string();
    }
    if let Some(origin_host) = trimmed_origin_host {
        return origin_host.to_string();
    }

    crate::sources::provenance::LOCAL_SOURCE_ID.to_string()
}

fn normalized_search_hit_origin_kind(source_id: &str, origin_kind: Option<&str>) -> String {
    if let Some(kind) = origin_kind.map(str::trim).filter(|value| !value.is_empty()) {
        if kind.eq_ignore_ascii_case("local") {
            return crate::sources::provenance::LOCAL_SOURCE_ID.to_string();
        }
        if kind.eq_ignore_ascii_case("ssh") || kind.eq_ignore_ascii_case("remote") {
            return "remote".to_string();
        }
        return kind.to_ascii_lowercase();
    }

    if source_id == crate::sources::provenance::LOCAL_SOURCE_ID {
        crate::sources::provenance::LOCAL_SOURCE_ID.to_string()
    } else {
        "remote".to_string()
    }
}

fn normalized_search_hit_source_id(hit: &SearchHit) -> String {
    normalized_search_hit_source_id_parts(
        hit.source_id.as_str(),
        hit.origin_kind.as_str(),
        hit.origin_host.as_deref(),
    )
}

impl SearchHitKey {
    fn from_hit(hit: &SearchHit) -> Self {
        Self {
            source_id: normalized_search_hit_source_id(hit),
            source_path: hit.source_path.clone(),
            conversation_id: hit.conversation_id,
            title: if hit.conversation_id.is_some() {
                String::new()
            } else {
                hit.title.trim().to_string()
            },
            line_number: hit.line_number,
            created_at: hit.created_at,
            content_hash: hit.content_hash,
        }
    }
}

impl Ord for SearchHitKey {
    fn cmp(&self, other: &Self) -> CmpOrdering {
        self.source_id
            .cmp(&other.source_id)
            .then_with(|| self.source_path.cmp(&other.source_path))
            .then_with(|| self.conversation_id.cmp(&other.conversation_id))
            .then_with(|| self.title.cmp(&other.title))
            .then_with(|| self.line_number.cmp(&other.line_number))
            .then_with(|| self.created_at.cmp(&other.created_at))
            .then_with(|| self.content_hash.cmp(&other.content_hash))
    }
}

impl PartialOrd for SearchHitKey {
    fn partial_cmp(&self, other: &Self) -> Option<CmpOrdering> {
        Some(self.cmp(other))
    }
}

const FEDERATED_RRF_K: f32 = 60.0;

#[derive(Debug)]
struct FederatedRankedHit {
    hit: SearchHit,
    shard_index: usize,
    shard_rank: usize,
    fused_score: f32,
}

fn federated_rrf_score(shard_rank: usize) -> f32 {
    1.0 / (FEDERATED_RRF_K + shard_rank as f32 + 1.0)
}

fn merge_federated_ranked_hits(mut ranked_hits: Vec<FederatedRankedHit>) -> Vec<SearchHit> {
    ranked_hits.sort_by(|a, b| {
        b.fused_score
            .total_cmp(&a.fused_score)
            .then_with(|| a.shard_rank.cmp(&b.shard_rank))
            .then_with(|| SearchHitKey::from_hit(&a.hit).cmp(&SearchHitKey::from_hit(&b.hit)))
            .then_with(|| a.shard_index.cmp(&b.shard_index))
    });
    ranked_hits
        .into_iter()
        .map(|mut ranked| {
            ranked.hit.score = ranked.fused_score;
            ranked.hit
        })
        .collect()
}

#[cfg(test)]
#[allow(dead_code)]
#[derive(Debug, Default, Clone)]
struct HybridScore {
    rrf: f32,
    lexical_rank: Option<usize>,
    semantic_rank: Option<usize>,
    lexical_score: Option<f32>,
    semantic_score: Option<f32>,
}

#[cfg(test)]
#[allow(dead_code)]
#[derive(Debug, Clone)]
struct FusedHit {
    key: SearchHitKey,
    score: HybridScore,
    hit: SearchHit,
}

/// Whitespace-invariant content hash used for search-hit dedup.
///
/// Uses xxhash3-64 (via `xxhash-rust`) for ~4-10x throughput over the prior
/// hand-rolled FNV-1a byte loop on the 1-2 KB tool-output bodies that
/// dominate the corpus. The hash value is in-memory only (dedup keys), never
/// persisted, so switching algorithms requires no migration. The canonical
/// byte stream fed to the hasher is: each whitespace-separated token
/// followed by a single 0x20 space between tokens — identical tokenization
/// rules as the former FNV implementation, so dedup semantics are preserved.
pub(crate) fn stable_content_hash(content: &str) -> u64 {
    use xxhash_rust::xxh3::Xxh3;
    let mut hasher = Xxh3::new();
    let mut first = true;
    for token in content.split_whitespace() {
        if !first {
            hasher.update(b" ");
        }
        hasher.update(token.as_bytes());
        first = false;
    }
    hasher.digest()
}

fn stable_hit_hash(
    content: &str,
    source_path: &str,
    line_number: Option<usize>,
    created_at: Option<i64>,
) -> u64 {
    use xxhash_rust::xxh3::Xxh3;
    let mut hasher = Xxh3::new();
    // Seed with the whitespace-normalized content hash for empty-body
    // stability (matches the former FNV_OFFSET fallback).
    if !content.is_empty() {
        hasher.update(&stable_content_hash(content).to_le_bytes());
    }
    hasher.update(b"|");
    hasher.update(source_path.as_bytes());
    hasher.update(b"|");
    if let Some(line) = line_number {
        let mut buf = itoa::Buffer::new();
        hasher.update(buf.format(line).as_bytes());
    }
    hasher.update(b"|");
    if let Some(ts) = created_at {
        let mut buf = itoa::Buffer::new();
        hasher.update(buf.format(ts).as_bytes());
    }
    hasher.digest()
}

fn search_hit_key_doc_id(key: &SearchHitKey) -> String {
    // Unit Separator (0x1F) is extremely unlikely in filesystem paths/ids.
    // Bead num7z: build the stable dedup key directly into a pre-sized
    // String, branching on each Option instead of allocating throwaway
    // per-field Strings via `.map(|v| v.to_string())`. Output must stay
    // byte-identical to the prior `format!`-based implementation: empty
    // string for `None` optional fields, the integer's `Display` rendering
    // otherwise, all joined by 0x1F.
    use std::fmt::Write as _;
    const SEP: char = '\u{1f}';
    // 20 bytes covers the decimal rendering of any i64/usize/u64.
    let capacity = key.source_id.len()
        + key.source_path.len()
        + key.title.len()
        + 6 // six separators
        + 3 * 20 // three possibly-empty i64/usize fields
        + 20; // content_hash u64
    let mut out = String::with_capacity(capacity);
    out.push_str(&key.source_id);
    out.push(SEP);
    out.push_str(&key.source_path);
    out.push(SEP);
    if let Some(v) = key.conversation_id {
        let _ = write!(out, "{v}");
    }
    out.push(SEP);
    out.push_str(&key.title);
    out.push(SEP);
    if let Some(v) = key.line_number {
        let _ = write!(out, "{v}");
    }
    out.push(SEP);
    if let Some(v) = key.created_at {
        let _ = write!(out, "{v}");
    }
    out.push(SEP);
    let _ = write!(out, "{}", key.content_hash);
    out
}

fn search_hit_doc_id(hit: &SearchHit) -> String {
    search_hit_key_doc_id(&SearchHitKey::from_hit(hit))
}

/// Comparator for FusedHit: descending RRF score, prefer dual-source, then key for determinism.
#[cfg(test)]
fn cmp_fused_hit_desc(a: &FusedHit, b: &FusedHit) -> CmpOrdering {
    b.score
        .rrf
        .total_cmp(&a.score.rrf)
        .then_with(|| {
            let a_both = a.score.lexical_rank.is_some() && a.score.semantic_rank.is_some();
            let b_both = b.score.lexical_rank.is_some() && b.score.semantic_rank.is_some();
            match (b_both, a_both) {
                (true, false) => CmpOrdering::Greater,
                (false, true) => CmpOrdering::Less,
                _ => CmpOrdering::Equal,
            }
        })
        .then_with(|| a.key.cmp(&b.key))
}

/// Threshold below which full sort is faster than quickselect + partial sort.
#[cfg(test)]
#[allow(dead_code)]
const QUICKSELECT_THRESHOLD: usize = 64;

/// Partition fused hits to get top-k in O(N + k log k) instead of O(N log N).
///
/// For k << N, this is significantly faster than sorting all N elements.
/// Uses `select_nth_unstable_by` for O(N) average-case partitioning,
/// then sorts only the top-k elements.
///
/// Note: Currently only used for tests. Production code uses full sort for
/// content deduplication which requires seeing all elements.
#[cfg(test)]
#[allow(dead_code)]
fn top_k_fused(mut hits: Vec<FusedHit>, k: usize) -> Vec<FusedHit> {
    let n = hits.len();

    // Edge cases: nothing to do or k >= n
    if n == 0 || k == 0 {
        return Vec::new();
    }
    if k >= n {
        hits.sort_by(cmp_fused_hit_desc);
        return hits;
    }

    // For small N, full sort has less overhead than quickselect
    if n < QUICKSELECT_THRESHOLD {
        hits.sort_by(cmp_fused_hit_desc);
        hits.truncate(k);
        return hits;
    }

    // Partition: move top-k elements to the front (unordered) in O(N)
    hits.select_nth_unstable_by(k - 1, cmp_fused_hit_desc);

    // Truncate to just the top-k elements
    hits.truncate(k);

    // Sort just the top-k in O(k log k)
    hits.sort_by(cmp_fused_hit_desc);

    hits
}

/// Fuse lexical + semantic hits using Reciprocal Rank Fusion (RRF).
/// Applies deterministic tie-breaking and returns the requested page slice.
pub fn rrf_fuse_hits(
    lexical: &[SearchHit],
    semantic: &[SearchHit],
    query: &str,
    limit: usize,
    offset: usize,
) -> Vec<SearchHit> {
    if limit == 0 {
        return Vec::new();
    }
    let total_candidates = lexical.len().saturating_add(semantic.len());
    if total_candidates == 0 {
        return Vec::new();
    }

    let mut lexical_scored = Vec::with_capacity(lexical.len());
    let mut semantic_scored = Vec::with_capacity(semantic.len());
    let mut hit_by_doc_id: HashMap<String, SearchHit> = HashMap::with_capacity(total_candidates);

    for hit in lexical {
        let doc_id = search_hit_doc_id(hit);
        // Prefer lexical hit details (snippets highlight query terms).
        hit_by_doc_id.insert(doc_id.clone(), hit.clone());
        lexical_scored.push(FsScoredResult {
            doc_id,
            score: hit.score,
            source: FsScoreSource::Lexical,
            index: None,
            fast_score: None,
            quality_score: None,
            lexical_score: Some(hit.score),
            rerank_score: None,
            explanation: None,
            metadata: None,
        });
    }

    for (idx, hit) in semantic.iter().enumerate() {
        let doc_id = search_hit_doc_id(hit);
        hit_by_doc_id
            .entry(doc_id.clone())
            .or_insert_with(|| hit.clone());
        semantic_scored.push(FsVectorHit {
            index: u32::try_from(idx).unwrap_or(u32::MAX),
            score: hit.score,
            doc_id,
        });
    }

    // Ask frankensearch for full fused ordering so we can preserve cass's
    // content-level deduplication/pagination semantics afterward.
    let fused = fs_rrf_fuse(
        &lexical_scored,
        &semantic_scored,
        total_candidates,
        0,
        &FsRrfConfig::default(),
    );

    // Dedup by (source_id, source_path, conversation_id-or-title, line_number,
    // created_at, content_hash) while preserving RRF order. When a real
    // conversation_id is present, it is the authoritative session key and title
    // drift must not split the same conversation.
    #[derive(Clone, Copy)]
    struct CompatSlot {
        index: usize,
        conversation_id: Option<i64>,
        ambiguous: bool,
    }

    let mut source_ids: HashMap<String, u32> = HashMap::new();
    let mut path_ids: HashMap<String, u32> = HashMap::new();
    let mut title_ids: HashMap<String, u32> = HashMap::new();
    let mut next_source_id: u32 = 0;
    let mut next_path_id: u32 = 0;
    let mut next_title_id: u32 = 0;
    type CompatExactKey = (
        u32,
        u32,
        Option<i64>,
        Option<u32>,
        Option<usize>,
        Option<i64>,
        u64,
    );
    type CompatFallbackKey = (u32, u32, u32, Option<usize>, Option<i64>, u64);

    let mut exact_seen: HashMap<CompatExactKey, usize> = HashMap::with_capacity(fused.len());
    let mut fallback_seen: HashMap<CompatFallbackKey, CompatSlot> =
        HashMap::with_capacity(fused.len());
    let mut unique_hits: Vec<SearchHit> = Vec::with_capacity(fused.len());

    let update_slot = |slot: &mut CompatSlot, conversation_id: Option<i64>| {
        if slot.ambiguous {
            return;
        }
        match (slot.conversation_id, conversation_id) {
            (Some(existing), Some(current)) if existing != current => slot.ambiguous = true,
            (None, Some(current)) => slot.conversation_id = Some(current),
            _ => {}
        }
    };

    for fused_hit in fused {
        let mut hit = match hit_by_doc_id.remove(&fused_hit.doc_id) {
            Some(hit) => hit,
            None => continue,
        };
        if hit_is_noise(&hit, query) {
            continue;
        }

        let normalized_source_id = normalized_search_hit_source_id(&hit);
        let source_key = if let Some(id) = source_ids.get(normalized_source_id.as_str()) {
            *id
        } else {
            let id = next_source_id;
            next_source_id = next_source_id.saturating_add(1);
            source_ids.insert(normalized_source_id, id);
            id
        };
        let path_key = if let Some(id) = path_ids.get(hit.source_path.as_str()) {
            *id
        } else {
            let id = next_path_id;
            next_path_id = next_path_id.saturating_add(1);
            path_ids.insert(hit.source_path.clone(), id);
            id
        };
        let normalized_title = hit.title.trim();
        let fallback_title_key = if let Some(id) = title_ids.get(normalized_title) {
            *id
        } else {
            let id = next_title_id;
            next_title_id = next_title_id.saturating_add(1);
            title_ids.insert(normalized_title.to_string(), id);
            id
        };
        let exact_title_key = if hit.conversation_id.is_some() {
            None
        } else {
            Some(fallback_title_key)
        };
        let exact_key = (
            source_key,
            path_key,
            hit.conversation_id,
            exact_title_key,
            hit.line_number,
            hit.created_at,
            hit.content_hash,
        );
        let fallback_key = (
            source_key,
            path_key,
            fallback_title_key,
            hit.line_number,
            hit.created_at,
            hit.content_hash,
        );

        let merged_idx = exact_seen.get(&exact_key).copied().or_else(|| {
            fallback_seen.get(&fallback_key).and_then(|slot| {
                if slot.ambiguous {
                    return None;
                }
                match (slot.conversation_id, hit.conversation_id) {
                    (Some(existing), Some(current)) if existing != current => None,
                    _ => Some(slot.index),
                }
            })
        });

        if let Some(existing_idx) = merged_idx {
            exact_seen.insert(exact_key, existing_idx);
            let slot = fallback_seen.entry(fallback_key).or_insert(CompatSlot {
                index: existing_idx,
                conversation_id: hit.conversation_id,
                ambiguous: false,
            });
            update_slot(slot, hit.conversation_id);
            if unique_hits[existing_idx].conversation_id.is_none() && hit.conversation_id.is_some()
            {
                unique_hits[existing_idx].conversation_id = hit.conversation_id;
            }
            unique_hits[existing_idx].score += fused_hit.rrf_score as f32;
            continue;
        }

        hit.score = fused_hit.rrf_score as f32;
        let index = unique_hits.len();
        unique_hits.push(hit);
        exact_seen.insert(exact_key, index);
        match fallback_seen.get_mut(&fallback_key) {
            Some(slot) => update_slot(slot, unique_hits[index].conversation_id),
            None => {
                fallback_seen.insert(
                    fallback_key,
                    CompatSlot {
                        index,
                        conversation_id: unique_hits[index].conversation_id,
                        ambiguous: false,
                    },
                );
            }
        }
    }

    unique_hits.sort_by(|a, b| {
        b.score
            .total_cmp(&a.score)
            .then_with(|| SearchHitKey::from_hit(a).cmp(&SearchHitKey::from_hit(b)))
    });

    let start = offset.min(unique_hits.len());
    unique_hits.into_iter().skip(start).take(limit).collect()
}

struct QueryCache {
    embedder_id: String,
    embeddings: LruCache<String, Vec<f32>>,
}

impl QueryCache {
    fn new(embedder_id: &str, capacity: NonZeroUsize) -> Self {
        Self {
            embedder_id: embedder_id.to_string(),
            embeddings: LruCache::new(capacity),
        }
    }

    fn align_embedder(&mut self, embedder: &dyn Embedder) {
        if self.embedder_id != embedder.id() {
            self.embedder_id = embedder.id().to_string();
            self.embeddings.clear();
        }
    }

    fn get_cached(&mut self, embedder: &dyn Embedder, canonical: &str) -> Option<Vec<f32>> {
        self.align_embedder(embedder);
        self.embeddings.get(canonical).cloned()
    }

    fn store(&mut self, embedder: &dyn Embedder, canonical: &str, embedding: Vec<f32>) {
        self.align_embedder(embedder);
        self.embeddings.put(canonical.to_string(), embedding);
    }
}

/// Returns `Some(&filter)` when the filter has at least one active constraint,
/// `None` when unrestricted (skip filtering for performance).
fn semantic_filter_as_search_filter(filter: &SemanticFilter) -> Option<&dyn FsSearchFilter> {
    let unrestricted = filter.agents.is_none()
        && filter.workspaces.is_none()
        && filter.sources.is_none()
        && filter.roles.is_none()
        && filter.created_from.is_none()
        && filter.created_to.is_none();
    if unrestricted { None } else { Some(filter) }
}

fn open_fs_semantic_ann_index(fs_index: &FsVectorIndex, ann_path: &Path) -> Result<FsHnswIndex> {
    if !ann_path.is_file() {
        bail!(
            "approximate search unavailable: HNSW index not found at {}",
            ann_path.display()
        );
    }

    let ann = FsHnswIndex::load(ann_path, fs_index)
        .map_err(|err| anyhow!("open HNSW index failed: {err}"))?;
    let matches = ann
        .matches_vector_index(fs_index)
        .map_err(|err| anyhow!("validate HNSW index failed: {err}"))?;
    if !matches {
        bail!(
            "approximate search unavailable: HNSW index at {} is stale for current semantic index (run 'cass index --semantic --build-hnsw')",
            ann_path.display()
        );
    }

    Ok(ann)
}

struct SemanticSearchState {
    context_token: Arc<()>,
    embedder: Arc<dyn Embedder>,
    fs_semantic_index: Arc<FsVectorIndex>,
    fs_semantic_indexes: Arc<Vec<Arc<FsVectorIndex>>>,
    fs_ann_index: Option<Arc<FsHnswIndex>>,
    ann_path: Option<PathBuf>,
    fs_in_memory_two_tier_index: Option<Arc<FsInMemoryTwoTierIndex>>,
    in_memory_two_tier_unavailable: InMemoryTwoTierUnavailable,
    progressive_context: Option<Arc<ProgressiveTwoTierContext>>,
    progressive_context_unavailable: bool,
    filter_maps: SemanticFilterMaps,
    roles: Option<HashSet<u8>>,
    query_cache: QueryCache,
}

#[derive(Debug, Clone, Copy, Default)]
struct InMemoryTwoTierUnavailable {
    fast_only: bool,
    quality: bool,
}

impl InMemoryTwoTierUnavailable {
    fn is_known_unavailable(self, tier_mode: SemanticTierMode) -> bool {
        match tier_mode {
            SemanticTierMode::Single => false,
            SemanticTierMode::FastOnly => self.fast_only,
            SemanticTierMode::Progressive | SemanticTierMode::QualityOnly => self.quality,
        }
    }

    fn mark_unavailable(&mut self, tier_mode: SemanticTierMode) {
        match tier_mode {
            SemanticTierMode::Single => {}
            SemanticTierMode::FastOnly => {
                self.fast_only = true;
            }
            SemanticTierMode::Progressive | SemanticTierMode::QualityOnly => {
                self.quality = true;
            }
        }
    }
}

struct ProgressiveTwoTierContext {
    context_token: Arc<()>,
    index: Arc<FsTwoTierIndex>,
    fast_embedder: Arc<dyn frankensearch::Embedder>,
    quality_embedder: Option<Arc<dyn frankensearch::Embedder>>,
}

#[derive(Clone)]
struct SemanticCandidateContext {
    fs_semantic_index: Arc<FsVectorIndex>,
    fs_semantic_indexes: Arc<Vec<Arc<FsVectorIndex>>>,
    filter_maps: SemanticFilterMaps,
    roles: Option<HashSet<u8>>,
}

struct SemanticCandidateSearchRequest<'a> {
    fetch_limit: usize,
    approximate: bool,
    tier_mode: SemanticTierMode,
    in_memory_two_tier_index: Option<&'a Arc<FsInMemoryTwoTierIndex>>,
    ann_index: Option<&'a Arc<FsHnswIndex>>,
}

#[derive(Debug, Clone, Copy, Default)]
struct SemanticCandidateRetryState {
    has_more_candidates: bool,
    exact_window_may_omit_competitor: bool,
}

struct SemanticQueryEmbedding {
    context_token: Arc<()>,
    vector: Vec<f32>,
}

struct SharedCassSyncEmbedder {
    inner: Arc<dyn Embedder>,
    cache: Mutex<LruCache<String, Vec<f32>>>,
}

impl SharedCassSyncEmbedder {
    fn new(inner: Arc<dyn Embedder>) -> Self {
        let cache_capacity =
            NonZeroUsize::new(PROGRESSIVE_EMBEDDING_CACHE_CAPACITY).expect("cache capacity > 0");
        Self {
            inner,
            cache: Mutex::new(LruCache::new(cache_capacity)),
        }
    }
}

impl Embedder for SharedCassSyncEmbedder {
    fn embed_sync(&self, text: &str) -> crate::search::embedder::EmbedderResult<Vec<f32>> {
        if let Ok(mut cache) = self.cache.lock()
            && let Some(embedding) = cache.get(text).cloned()
        {
            return Ok(embedding);
        }

        let embedding = self.inner.embed_sync(text)?;
        if let Ok(mut cache) = self.cache.lock() {
            cache.put(text.to_owned(), embedding.clone());
        }
        Ok(embedding)
    }

    fn embed_batch_sync(
        &self,
        texts: &[&str],
    ) -> crate::search::embedder::EmbedderResult<Vec<Vec<f32>>> {
        self.inner.embed_batch_sync(texts)
    }

    fn dimension(&self) -> usize {
        self.inner.dimension()
    }

    fn id(&self) -> &str {
        self.inner.id()
    }

    fn model_name(&self) -> &str {
        self.inner.model_name()
    }

    fn is_ready(&self) -> bool {
        self.inner.is_ready()
    }

    fn is_semantic(&self) -> bool {
        self.inner.is_semantic()
    }

    fn category(&self) -> frankensearch::ModelCategory {
        self.inner.category()
    }

    fn tier(&self) -> frankensearch::ModelTier {
        self.inner.tier()
    }

    fn supports_mrl(&self) -> bool {
        self.inner.supports_mrl()
    }
}

fn build_in_memory_two_tier_index(
    ann_path: Option<PathBuf>,
    embedder_id: &str,
    tier_mode: SemanticTierMode,
) -> Option<Arc<FsInMemoryTwoTierIndex>> {
    let index_dir = ann_path
        .as_ref()
        .and_then(|path| path.parent().map(Path::to_path_buf));
    let Some(index_dir) = index_dir else {
        tracing::debug!("two-tier semantic unavailable: ann/index directory path missing");
        return None;
    };

    match FsInMemoryTwoTierIndex::from_dir(&index_dir) {
        Ok(index) => return Some(Arc::new(index)),
        Err(err) => {
            tracing::debug!(
                dir = %index_dir.display(),
                error = %err,
                "two-tier semantic index load failed; considering fallback"
            );
        }
    }

    if !matches!(tier_mode, SemanticTierMode::FastOnly) {
        return None;
    }

    let fallback_fast = index_dir.join(format!("index-{embedder_id}.fsvi"));
    if !fallback_fast.is_file() {
        return None;
    }

    match FsInMemoryVectorIndex::from_fsvi(&fallback_fast) {
        Ok(fast) => Some(Arc::new(FsInMemoryTwoTierIndex::new(fast, None))),
        Err(err) => {
            tracing::debug!(
                path = %fallback_fast.display(),
                error = %err,
                "fast-only semantic fallback index load failed"
            );
            None
        }
    }
}

fn two_tier_index_supports_mode(
    index: &FsInMemoryTwoTierIndex,
    tier_mode: SemanticTierMode,
) -> bool {
    !matches!(
        tier_mode,
        SemanticTierMode::Progressive | SemanticTierMode::QualityOnly
    ) || index.has_quality_index()
}

#[derive(Debug, Clone)]
struct ResolvedSemanticDocId {
    message_id: u64,
    doc_id: String,
}

type ProgressiveLookupKey = (String, String, Option<i64>, String, i64, Option<i64>, u64);
type ProgressiveExactQueryKey = (i64, i64);
type ProgressiveFallbackQueryKey = (String, String, i64);
type ResolvedSemanticLookupRow = Option<(ProgressiveLookupKey, ResolvedSemanticDocId)>;

#[derive(Debug, Clone)]
struct ProgressiveLexicalHit {
    title: String,
    snippet: String,
    content: String,
    content_hash: u64,
    conversation_id: Option<i64>,
    source_path: String,
    agent: String,
    workspace: String,
    workspace_original: Option<String>,
    created_at: Option<i64>,
    match_type: MatchType,
    line_number: Option<usize>,
    source_id: String,
    origin_kind: String,
    origin_host: Option<String>,
}

impl ProgressiveLexicalHit {
    fn from_search_hit(hit: &SearchHit, field_mask: FieldMask) -> Self {
        Self {
            title: if field_mask.wants_title() {
                hit.title.clone()
            } else {
                String::new()
            },
            snippet: if field_mask.wants_snippet() {
                hit.snippet.clone()
            } else {
                String::new()
            },
            content: if field_mask.needs_content() {
                hit.content.clone()
            } else {
                String::new()
            },
            content_hash: hit.content_hash,
            conversation_id: hit.conversation_id,
            source_path: hit.source_path.clone(),
            agent: hit.agent.clone(),
            workspace: hit.workspace.clone(),
            workspace_original: hit.workspace_original.clone(),
            created_at: hit.created_at,
            match_type: hit.match_type,
            line_number: hit.line_number,
            source_id: hit.source_id.clone(),
            origin_kind: hit.origin_kind.clone(),
            origin_host: hit.origin_host.clone(),
        }
    }

    fn to_search_hit(&self, score: f32) -> SearchHit {
        SearchHit {
            title: self.title.clone(),
            snippet: self.snippet.clone(),
            content: self.content.clone(),
            content_hash: self.content_hash,
            conversation_id: self.conversation_id,
            score,
            source_path: self.source_path.clone(),
            agent: self.agent.clone(),
            workspace: self.workspace.clone(),
            workspace_original: self.workspace_original.clone(),
            created_at: self.created_at,
            line_number: self.line_number,
            match_type: self.match_type,
            source_id: self.source_id.clone(),
            origin_kind: self.origin_kind.clone(),
            origin_host: self.origin_host.clone(),
        }
    }
}

#[derive(Debug, Default)]
struct ProgressiveLexicalCache {
    hits_by_message: HashMap<u64, ProgressiveLexicalHit>,
    wildcard_fallback: bool,
    suggestions: Vec<QuerySuggestion>,
}

#[derive(Clone, Copy)]
struct ProgressivePhaseContext<'a> {
    query: &'a str,
    filters: &'a SearchFilters,
    field_mask: FieldMask,
    lexical_cache: Option<&'a ProgressiveLexicalCache>,
    limit: usize,
    fetch_limit: usize,
}

type ProgressiveLexicalSnapshot = Arc<ProgressiveLexicalCache>;

struct CassProgressiveLexicalAdapter {
    client: Arc<SearchClient>,
    filters: SearchFilters,
    field_mask: FieldMask,
    sparse_threshold: usize,
    shared: Arc<Mutex<ProgressiveLexicalSnapshot>>,
}

impl CassProgressiveLexicalAdapter {
    fn new(
        client: Arc<SearchClient>,
        filters: SearchFilters,
        field_mask: FieldMask,
        sparse_threshold: usize,
        shared: Arc<Mutex<ProgressiveLexicalSnapshot>>,
    ) -> Self {
        Self {
            client,
            filters,
            field_mask,
            sparse_threshold,
            shared,
        }
    }
}

impl FsLexicalSearch for CassProgressiveLexicalAdapter {
    fn search<'a>(
        &'a self,
        cx: &'a FsCx,
        query: &'a str,
        limit: usize,
    ) -> FsSearchFuture<'a, Vec<FsScoredResult>> {
        Box::pin(async move {
            if cx.is_cancel_requested() {
                return Err(FsSearchError::Cancelled {
                    phase: "lexical".to_string(),
                    reason: "cancel requested".to_string(),
                });
            }

            let result = self
                .client
                .search_with_fallback(
                    query,
                    self.filters.clone(),
                    limit,
                    0,
                    self.sparse_threshold,
                    self.field_mask,
                )
                .map_err(|err| FsSearchError::SubsystemError {
                    subsystem: "cass_lexical_adapter",
                    source: Box::new(std::io::Error::other(err.to_string())),
                })?;

            let resolved = self
                .client
                .resolve_semantic_doc_ids_for_hits(&result.hits)
                .map_err(|err| FsSearchError::SubsystemError {
                    subsystem: "cass_lexical_adapter",
                    source: Box::new(std::io::Error::other(err.to_string())),
                })?;

            let mut scored = Vec::with_capacity(result.hits.len());
            let mut hits_by_message = HashMap::with_capacity(result.hits.len());

            for (hit, resolved_doc) in result.hits.iter().zip(resolved) {
                let Some(resolved_doc) = resolved_doc else {
                    continue;
                };
                hits_by_message
                    .entry(resolved_doc.message_id)
                    .or_insert_with(|| {
                        ProgressiveLexicalHit::from_search_hit(hit, self.field_mask)
                    });
                scored.push(FsScoredResult {
                    doc_id: resolved_doc.doc_id,
                    score: hit.score,
                    source: FsScoreSource::Lexical,
                    index: None,
                    fast_score: None,
                    quality_score: None,
                    lexical_score: Some(hit.score),
                    rerank_score: None,
                    explanation: None,
                    metadata: None,
                });
            }

            if let Ok(mut guard) = self.shared.lock() {
                *guard = Arc::new(ProgressiveLexicalCache {
                    hits_by_message,
                    wildcard_fallback: result.wildcard_fallback,
                    suggestions: result.suggestions,
                });
            }

            Ok(scored)
        })
    }

    fn index_document<'a>(
        &'a self,
        _cx: &'a FsCx,
        _doc: &'a frankensearch::IndexableDocument,
    ) -> FsSearchFuture<'a, ()> {
        Box::pin(async move {
            Err(FsSearchError::SubsystemError {
                subsystem: "cass_lexical_adapter",
                source: Box::new(std::io::Error::other("cass lexical adapter is read-only")),
            })
        })
    }

    fn commit<'a>(&'a self, _cx: &'a FsCx) -> FsSearchFuture<'a, ()> {
        Box::pin(async move { Ok(()) })
    }

    fn doc_count(&self) -> usize {
        self.client.total_docs()
    }
}

pub struct SearchClient {
    reader: Option<(IndexReader, FsCassFields)>,
    sqlite: Mutex<Option<SendConnection>>,
    sqlite_path: Option<PathBuf>,
    prefix_cache: Mutex<CacheShards>,
    reload_on_search: bool,
    last_reload: Mutex<Option<Instant>>,
    last_generation: Mutex<Option<u64>>,
    reload_epoch: Arc<AtomicU64>,
    warm_tx: Option<mpsc::Sender<WarmJob>>,
    _warm_handle: Option<std::thread::JoinHandle<()>>,
    metrics: Metrics,
    cache_namespace: String,
    semantic: Mutex<Option<SemanticSearchState>>,
    /// Total count from the most recent Tantivy query (via `Count` collector).
    /// Populated by `search_tantivy`, read by `search_with_fallback` to report
    /// the true total matching documents for `total_matches` in JSON output.
    last_tantivy_total_count: Mutex<Option<usize>>,
}

#[derive(Debug, Clone, Copy)]
pub struct SearchClientOptions {
    pub enable_reload: bool,
    pub enable_warm: bool,
}

impl Default for SearchClientOptions {
    fn default() -> Self {
        Self {
            enable_reload: true,
            enable_warm: true,
        }
    }
}

impl Drop for SearchClient {
    fn drop(&mut self) {
        FEDERATED_SEARCH_READERS
            .write()
            .remove(&self.cache_namespace);
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct CacheStats {
    pub cache_hits: u64,
    pub cache_miss: u64,
    pub cache_shortfall: u64,
    pub reloads: u64,
    pub reload_ms_total: u128,
    pub total_cap: usize,
    pub total_cost: usize,
    /// Total evictions since client creation
    pub eviction_count: u64,
    /// Approximate bytes used by cache (rough estimate)
    pub approx_bytes: usize,
    /// Effective byte cap for cached hits (0 = disabled by explicit operator override)
    pub byte_cap: usize,
    /// Active eviction/admission policy for prefix result cache
    pub eviction_policy: &'static str,
    /// Number of S3-FIFO ghost entries retained for adaptive admission
    pub ghost_entries: usize,
    /// Number of cache insertions rejected by adaptive admission
    pub admission_rejects: u64,
    /// Number of adaptive query prewarm jobs scheduled from hot prefix-cache state.
    pub prewarm_scheduled: u64,
    /// Number of adaptive query prewarm jobs skipped because cache pressure was high.
    pub prewarm_skipped_pressure: u64,
    /// Last observed Tantivy reader generation signature for cursor continuity metadata.
    pub reader_generation: Option<u64>,
}

impl Default for CacheStats {
    fn default() -> Self {
        Self {
            cache_hits: 0,
            cache_miss: 0,
            cache_shortfall: 0,
            reloads: 0,
            reload_ms_total: 0,
            total_cap: 0,
            total_cost: 0,
            eviction_count: 0,
            approx_bytes: 0,
            byte_cap: 0,
            eviction_policy: "unknown",
            ghost_entries: 0,
            admission_rejects: 0,
            prewarm_scheduled: 0,
            prewarm_skipped_pressure: 0,
            reader_generation: None,
        }
    }
}

// Cache tuning: read from env to allow runtime override without recompiling.
// CASS_CACHE_SHARD_CAP controls per-shard entries; default 256.
static CACHE_SHARD_CAP: Lazy<usize> = Lazy::new(|| {
    dotenvy::var("CASS_CACHE_SHARD_CAP")
        .ok()
        .and_then(|v| v.parse::<usize>().ok())
        .filter(|v| *v > 0)
        .unwrap_or(256)
});

// Total cache cost across all shards; approximate "~2k entries" default.
static CACHE_TOTAL_CAP: Lazy<usize> = Lazy::new(|| {
    dotenvy::var("CASS_CACHE_TOTAL_CAP")
        .ok()
        .and_then(|v| v.parse::<usize>().ok())
        .filter(|v| *v > 0)
        .unwrap_or(2048)
});

static CACHE_DEBUG_ENABLED: Lazy<bool> = Lazy::new(|| {
    dotenvy::var("CASS_DEBUG_CACHE_METRICS")
        .map(|v| v == "1" || v.eq_ignore_ascii_case("true"))
        .unwrap_or(false)
});

// Byte-based cap for cache memory. Unset defaults to a memory-proportional cap;
// explicit CASS_CACHE_BYTE_CAP=0 disables the byte guard.
static CACHE_BYTE_CAP: Lazy<usize> = Lazy::new(|| match dotenvy::var("CASS_CACHE_BYTE_CAP") {
    Ok(value) => cache_byte_cap_from_env_value(Some(&value), available_memory_bytes()),
    Err(_) => default_cache_byte_cap(),
});

static CACHE_EVICTION_POLICY: Lazy<CacheEvictionPolicy> = Lazy::new(|| {
    cache_eviction_policy_from_env_value(dotenvy::var("CASS_CACHE_EVICTION_POLICY").ok().as_deref())
});

const DEFAULT_CACHE_BYTE_CAP_FALLBACK: usize = 64 * 1024 * 1024;
const DEFAULT_CACHE_BYTE_CAP_MEMORY_FRACTION_DENOMINATOR: u64 = 128;
const DEFAULT_CACHE_BYTE_CAP_CEILING: u64 = 2 * 1024 * 1024 * 1024;
const S3_FIFO_GHOST_CAP_MULTIPLIER: usize = 2;
const S3_FIFO_LARGE_ENTRY_FRACTION_DENOMINATOR: usize = 4;
const PREWARM_ENTRY_PRESSURE_NUMERATOR: usize = 9;
const PREWARM_ENTRY_PRESSURE_DENOMINATOR: usize = 10;
const PREWARM_BYTE_PRESSURE_NUMERATOR: usize = 4;
const PREWARM_BYTE_PRESSURE_DENOMINATOR: usize = 5;

const CACHE_KEY_VERSION: &str = "1";

// Warm debounce (ms) for background reload/warm jobs; default 120ms.
static WARM_DEBOUNCE_MS: Lazy<u64> = Lazy::new(|| {
    dotenvy::var("CASS_WARM_DEBOUNCE_MS")
        .ok()
        .and_then(|v| v.parse::<u64>().ok())
        .filter(|v| *v > 0)
        .unwrap_or(120)
});

fn default_cache_byte_cap() -> usize {
    default_cache_byte_cap_for_available(available_memory_bytes())
}

fn cache_byte_cap_from_env_value(value: Option<&str>, available_bytes: Option<u64>) -> usize {
    let Some(raw) = value else {
        return default_cache_byte_cap_for_available(available_bytes);
    };
    raw.parse::<usize>()
        .unwrap_or_else(|_| default_cache_byte_cap_for_available(available_bytes))
}

fn default_cache_byte_cap_for_available(available_bytes: Option<u64>) -> usize {
    let Some(available_bytes) = available_bytes else {
        return DEFAULT_CACHE_BYTE_CAP_FALLBACK;
    };
    let ceiling = usize::try_from(DEFAULT_CACHE_BYTE_CAP_CEILING).unwrap_or(usize::MAX);
    let budget = available_bytes / DEFAULT_CACHE_BYTE_CAP_MEMORY_FRACTION_DENOMINATOR;
    let budget = budget.min(DEFAULT_CACHE_BYTE_CAP_CEILING);
    let budget = usize::try_from(budget).unwrap_or(ceiling);
    budget.clamp(DEFAULT_CACHE_BYTE_CAP_FALLBACK, ceiling)
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum CacheEvictionPolicy {
    Lru,
    S3Fifo,
}

impl CacheEvictionPolicy {
    fn label(self) -> &'static str {
        match self {
            CacheEvictionPolicy::Lru => "lru",
            CacheEvictionPolicy::S3Fifo => "s3-fifo",
        }
    }
}

fn cache_eviction_policy_from_env_value(value: Option<&str>) -> CacheEvictionPolicy {
    match value.map(str::trim).filter(|value| !value.is_empty()) {
        Some(value) if value.eq_ignore_ascii_case("s3-fifo") => CacheEvictionPolicy::S3Fifo,
        Some(value) if value.eq_ignore_ascii_case("s3fifo") => CacheEvictionPolicy::S3Fifo,
        Some(value) if value.eq_ignore_ascii_case("s3_fifo") => CacheEvictionPolicy::S3Fifo,
        _ => CacheEvictionPolicy::Lru,
    }
}

#[derive(Clone)]
struct CachedHit {
    hit: SearchHit,
    lc_content: String,
    lc_title: Option<String>,
    bloom64: u64,
}

impl CachedHit {
    /// Approximate byte size of this cached hit (rough estimate for memory guardrails).
    /// Includes `SearchHit` strings + lowercase copies + bloom filter.
    fn approx_bytes(&self) -> usize {
        // Base struct overhead
        let base = std::mem::size_of::<Self>();
        // SearchHit string fields (title, snippet, content, source_path, agent, workspace)
        let hit_strings = self.hit.title.len()
            + self.hit.snippet.len()
            + self.hit.content.len()
            + self.hit.source_path.len()
            + self.hit.agent.len()
            + self.hit.workspace.len()
            + self
                .hit
                .workspace_original
                .as_ref()
                .map_or(0, std::string::String::len)
            + self.hit.source_id.len()
            + self.hit.origin_kind.len()
            + self
                .hit
                .origin_host
                .as_ref()
                .map_or(0, std::string::String::len);
        // Lowercase cache copies
        let lc_strings =
            self.lc_content.len() + self.lc_title.as_ref().map_or(0, std::string::String::len);
        base + hit_strings + lc_strings
    }
}

struct CacheShards {
    // Optimization 2.3: Use Arc<str> for cache keys to reduce memory via interning
    shards: HashMap<Arc<str>, LruCache<Arc<str>, Vec<CachedHit>>>,
    total_cap: usize,
    total_cost: usize,
    /// Running count of evictions (for diagnostics)
    eviction_count: u64,
    /// Approximate bytes used by all cached hits
    total_bytes: usize,
    /// Byte cap (0 = disabled)
    byte_cap: usize,
    /// Active cache admission/eviction policy.
    policy: CacheEvictionPolicy,
    /// Ghost queue used by S3-FIFO-style adaptive admission.
    ghost_keys: VecDeque<Arc<str>>,
    ghost_set: HashSet<Arc<str>>,
    admission_rejects: u64,
}

impl CacheShards {
    fn new(total_cap: usize, byte_cap: usize) -> Self {
        Self::new_with_policy(total_cap, byte_cap, *CACHE_EVICTION_POLICY)
    }

    fn new_with_policy(total_cap: usize, byte_cap: usize, policy: CacheEvictionPolicy) -> Self {
        Self {
            shards: HashMap::new(),
            total_cap: total_cap.max(1),
            total_cost: 0,
            eviction_count: 0,
            total_bytes: 0,
            byte_cap,
            policy,
            ghost_keys: VecDeque::new(),
            ghost_set: HashSet::new(),
            admission_rejects: 0,
        }
    }

    fn shard_mut(&mut self, name: &str) -> &mut LruCache<Arc<str>, Vec<CachedHit>> {
        // Use interned shard names to reduce memory for repeated lookups
        let interned_name = intern_cache_key(name);
        self.shards
            .entry(interned_name)
            .or_insert_with(|| LruCache::new(NonZeroUsize::new(*CACHE_SHARD_CAP).unwrap()))
    }

    fn shard_opt(&self, name: &str) -> Option<&LruCache<Arc<str>, Vec<CachedHit>>> {
        // HashMap<Arc<str>, _> can be queried with &str via Borrow trait
        self.shards.get(name)
    }

    fn put(&mut self, shard_name: &str, key: Arc<str>, value: Vec<CachedHit>) {
        let new_cost = value.len();
        let new_bytes: usize = value.iter().map(CachedHit::approx_bytes).sum();
        let replacing = self
            .shard_opt(shard_name)
            .is_some_and(|shard| shard.contains(&key));

        if !replacing && !self.should_admit(&key, new_cost, new_bytes) {
            self.admission_rejects += 1;
            self.record_ghost(key);
            return;
        }

        self.remove_ghost(&key);

        let shard = self.shard_mut(shard_name);
        let old_val = shard.put(key, value);
        let (old_cost, old_bytes) = old_val.as_ref().map_or((0, 0), |v| {
            (v.len(), v.iter().map(CachedHit::approx_bytes).sum())
        });

        self.total_cost = self
            .total_cost
            .saturating_add(new_cost)
            .saturating_sub(old_cost);
        self.total_bytes = self
            .total_bytes
            .saturating_add(new_bytes)
            .saturating_sub(old_bytes);
        self.evict_until_within_cap();
    }

    fn evict_until_within_cap(&mut self) {
        // Evict if over entry cap OR over byte cap (when byte_cap > 0)
        while self.total_cost > self.total_cap
            || (self.byte_cap > 0 && self.total_bytes > self.byte_cap)
        {
            // Under byte pressure, target the byte-heaviest shard. Otherwise,
            // target the shard with the most cached items. This avoids
            // evicting many small useful entries before a single oversized
            // result set is finally removed.
            let byte_pressure = self.byte_cap > 0 && self.total_bytes > self.byte_cap;
            let mut largest_shard_key = None;
            let mut max_score = 0usize;
            for (k, v) in self.shards.iter() {
                let score = if byte_pressure {
                    shard_cached_bytes(v)
                } else {
                    v.len()
                };
                if score > max_score {
                    max_score = score;
                    largest_shard_key = Some(k.clone());
                }
            }

            if let Some(key) = largest_shard_key {
                if let Some(shard) = self.shards.get_mut(&key)
                    && let Some((evicted_key, v)) = shard.pop_lru()
                {
                    let evicted_bytes: usize = v.iter().map(CachedHit::approx_bytes).sum();
                    self.total_cost = self.total_cost.saturating_sub(v.len());
                    self.total_bytes = self.total_bytes.saturating_sub(evicted_bytes);
                    self.eviction_count += 1;
                    self.record_ghost(evicted_key);
                }
            } else {
                break; // All shards are empty
            }
        }
    }

    fn should_admit(&self, key: &Arc<str>, cost: usize, bytes: usize) -> bool {
        if self.policy == CacheEvictionPolicy::Lru || self.ghost_set.contains(key) {
            return true;
        }
        !self.is_s3_fifo_large_candidate(cost, bytes)
    }

    fn is_s3_fifo_large_candidate(&self, cost: usize, bytes: usize) -> bool {
        let entry_heavy = cost
            > self
                .total_cap
                .div_ceil(S3_FIFO_LARGE_ENTRY_FRACTION_DENOMINATOR);
        let byte_heavy = self.byte_cap > 0
            && bytes
                > self
                    .byte_cap
                    .div_ceil(S3_FIFO_LARGE_ENTRY_FRACTION_DENOMINATOR);
        entry_heavy || byte_heavy
    }

    fn record_ghost(&mut self, key: Arc<str>) {
        if self.policy != CacheEvictionPolicy::S3Fifo {
            return;
        }
        if self.ghost_set.insert(key.clone()) {
            self.ghost_keys.push_back(key);
        }
        let cap = self
            .total_cap
            .saturating_mul(S3_FIFO_GHOST_CAP_MULTIPLIER)
            .max(1);
        while self.ghost_set.len() > cap {
            if let Some(old) = self.ghost_keys.pop_front() {
                self.ghost_set.remove(&old);
            } else {
                break;
            }
        }
    }

    fn remove_ghost(&mut self, key: &Arc<str>) {
        self.ghost_set.remove(key);
        self.ghost_keys.retain(|candidate| candidate != key);
    }

    fn clear(&mut self) {
        self.shards.clear();
        self.total_cost = 0;
        self.total_bytes = 0;
        self.ghost_keys.clear();
        self.ghost_set.clear();
        // Note: eviction_count preserved for lifetime stats
    }

    fn total_cost(&self) -> usize {
        self.total_cost
    }

    fn total_cap(&self) -> usize {
        self.total_cap
    }

    fn eviction_count(&self) -> u64 {
        self.eviction_count
    }

    fn total_bytes(&self) -> usize {
        self.total_bytes
    }

    fn byte_cap(&self) -> usize {
        self.byte_cap
    }

    fn policy_label(&self) -> &'static str {
        self.policy.label()
    }

    fn ghost_entries(&self) -> usize {
        self.ghost_set.len()
    }

    fn admission_rejects(&self) -> u64 {
        self.admission_rejects
    }

    fn prewarm_pressure(&self) -> bool {
        let entry_pressure = self
            .total_cost
            .saturating_mul(PREWARM_ENTRY_PRESSURE_DENOMINATOR)
            >= self
                .total_cap
                .saturating_mul(PREWARM_ENTRY_PRESSURE_NUMERATOR);
        let byte_pressure = self.byte_cap > 0
            && self
                .total_bytes
                .saturating_mul(PREWARM_BYTE_PRESSURE_DENOMINATOR)
                >= self
                    .byte_cap
                    .saturating_mul(PREWARM_BYTE_PRESSURE_NUMERATOR);
        entry_pressure || byte_pressure
    }
}

fn shard_cached_bytes(shard: &LruCache<Arc<str>, Vec<CachedHit>>) -> usize {
    shard
        .iter()
        .map(|(_key, hits)| hits.iter().map(CachedHit::approx_bytes).sum::<usize>())
        .sum()
}

#[derive(Clone)]
struct WarmJob {
    query: String,
    filters_fingerprint: String,
    shard_name: String,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum AdaptivePrewarmDecision {
    Schedule,
    SkipCold,
    SkipPressure,
}

#[derive(Clone)]
struct SearcherCacheEntry {
    epoch: u64,
    reader_key: usize,
    searcher: Searcher,
}

thread_local! {
    static THREAD_SEARCHER: RefCell<Option<SearcherCacheEntry>> = const { RefCell::new(None) };
}

#[derive(Clone)]
struct FederatedIndexReader {
    reader: IndexReader,
    fields: FsCassFields,
}

static FEDERATED_SEARCH_READERS: Lazy<RwLock<HashMap<String, Arc<Vec<FederatedIndexReader>>>>> =
    Lazy::new(|| RwLock::new(HashMap::new()));
static SEARCH_CLIENT_INSTANCE_COUNTER: AtomicU64 = AtomicU64::new(1);

/// Calculate Levenshtein edit distance between two strings.
/// Used for typo detection in did-you-mean suggestions.
fn levenshtein_distance(a: &str, b: &str) -> usize {
    let a_chars: Vec<char> = a.chars().collect();
    let b_chars: Vec<char> = b.chars().collect();
    let a_len = a_chars.len();
    let b_len = b_chars.len();

    if a_len == 0 {
        return b_len;
    }
    if b_len == 0 {
        return a_len;
    }

    // Use two rows for space efficiency
    let mut prev_row: Vec<usize> = (0..=b_len).collect();
    let mut curr_row: Vec<usize> = vec![0; b_len + 1];

    for (i, a_char) in a_chars.iter().enumerate() {
        curr_row[0] = i + 1;
        for (j, b_char) in b_chars.iter().enumerate() {
            let cost = usize::from(a_char != b_char);
            curr_row[j + 1] = (prev_row[j + 1] + 1) // deletion
                .min(curr_row[j] + 1) // insertion
                .min(prev_row[j] + cost); // substitution
        }
        std::mem::swap(&mut prev_row, &mut curr_row);
    }

    prev_row[b_len]
}

/// Normalize a term into FTS5-porter-aligned parts.
/// Splits punctuation into separate fragments while preserving a trailing `*`
/// on the final fragment so fallback queries match how SQLite tokenizes indexed
/// text in `fts_messages`.
fn normalize_term_parts(raw: &str) -> Vec<String> {
    let mut parts = Vec::new();
    for token in nfc_sanitize_query(raw).split_whitespace() {
        let mut current = String::new();
        let mut chars = token.chars().peekable();
        while let Some(ch) = chars.next() {
            let trailing_wildcard = ch == '*' && chars.peek().is_none() && !current.is_empty();
            if ch.is_alphanumeric() || ch == '_' || trailing_wildcard {
                current.push(ch);
                continue;
            }

            if !current.is_empty() {
                parts.push(std::mem::take(&mut current));
            }
        }

        if !current.is_empty() {
            parts.push(current);
        }
    }
    parts
}

/// Normalize phrase text into tokenizer-aligned terms (lowercased, no wildcards).
fn normalize_phrase_terms(raw: &str) -> Vec<String> {
    normalize_term_parts(raw)
        .into_iter()
        .map(|s| s.trim_matches('*').to_lowercase())
        .filter(|s| !s.is_empty())
        .collect()
}

fn render_fts5_term_part(part: &str) -> Option<String> {
    let pattern = FsCassWildcardPattern::parse(part);
    if matches!(
        pattern,
        FsCassWildcardPattern::Suffix(_)
            | FsCassWildcardPattern::Substring(_)
            | FsCassWildcardPattern::Complex(_)
    ) {
        return None;
    }

    Some(part.to_string())
}

/// Determine the dominant match type from a query string.
/// Returns the "loosest" pattern used (Substring > Suffix > Prefix > Exact).
fn dominant_match_type(query: &str) -> MatchType {
    let mut worst = MatchType::Exact;
    for term in query.split_whitespace() {
        let pattern = FsCassWildcardPattern::parse(term);
        let mt = match pattern {
            FsCassWildcardPattern::Exact(_) => MatchType::Exact,
            FsCassWildcardPattern::Prefix(_) => MatchType::Prefix,
            FsCassWildcardPattern::Suffix(_) => MatchType::Suffix,
            FsCassWildcardPattern::Substring(_) => MatchType::Substring,
            FsCassWildcardPattern::Complex(_) => MatchType::Wildcard,
        };
        // Lower quality factor = "looser" match = dominant
        if mt.quality_factor() < worst.quality_factor() {
            worst = mt;
        }
    }
    worst
}

/// Check if content is primarily a tool invocation (noise that shouldn't appear in search results).
/// Tool invocations like "[Tool: Bash - Check status]" are not informative search results.
pub(crate) fn is_tool_invocation_noise(content: &str) -> bool {
    let trimmed = content.trim();

    // Direct tool invocations that are just "[Tool: X - description]" or "[Tool: X] args"
    if trimmed.starts_with("[Tool:") {
        // Find closing bracket
        if let Some(close_idx) = trimmed.find(']') {
            // Check for content after closing bracket (Pi-Agent style: "[Tool: name] args")
            let after = &trimmed[close_idx + 1..];
            if !after.trim().is_empty() {
                return false; // Has args/content after -> Keep
            }

            // No content after bracket. Check for description inside.
            // Format: "[Tool: Name - Desc]" (useful) vs "[Tool: Name]" (previously noise, now kept)
            // We now keep "[Tool: Name]" because users might search for "Tool: Bash" to find usage.
            // Only "[Tool:]" or "[Tool: ]" (empty name) is considered noise.
            let inner = &trimmed[6..close_idx]; // Skip "[Tool:"
            return inner.trim().is_empty();
        }
        // No closing bracket? Malformed, treat as noise
        return true;
    }

    // Also filter very short content that's just tool names or markers
    if trimmed.len() < 20 {
        let lower = trimmed.to_lowercase();
        if lower.starts_with("[tool") || lower.starts_with("tool:") {
            return true;
        }
    }

    false
}

fn hit_content_for_noise_check(hit: &SearchHit) -> &str {
    if hit.content.is_empty() {
        &hit.snippet
    } else {
        &hit.content
    }
}

fn hit_is_noise(hit: &SearchHit, query: &str) -> bool {
    let content_to_check = hit_content_for_noise_check(hit);
    // When both `content` and `snippet` are empty, it usually means the caller
    // explicitly asked for a projection (`--fields minimal` / `summary`) that
    // excludes both fields — NOT that the underlying row was empty. Treating
    // the hit as noise in that case silently drops every real match and makes
    // `cass search --fields minimal` return zero results even when matches
    // exist (reality-check bead q6xf9). The noise classifier cannot make a
    // correctness-preserving decision without text to inspect, so default to
    // "not noise" in that case and let the hit through; downstream projection
    // will apply the requested field subset.
    if content_to_check.is_empty() {
        return false;
    }
    is_search_noise_text(content_to_check, query) || is_tool_invocation_noise(content_to_check)
}

fn snippet_from_content(content: &str) -> String {
    let trimmed = content.trim();
    let mut chars = trimmed.chars();
    let preview: String = chars.by_ref().take(200).collect();
    if chars.next().is_some() {
        format!("{preview}...")
    } else {
        preview
    }
}

/// Deduplicate search hits by message-level provenance and content, keeping
/// only the highest-scored hit for each unique matched message.
///
/// This respects source boundaries (P2.3): the same content from different sources
/// appears as separate results, since they represent distinct conversations.
///
/// Also filters out tool invocation noise that isn't useful for search results.
#[cfg(test)]
pub(crate) fn deduplicate_hits(hits: Vec<SearchHit>) -> Vec<SearchHit> {
    deduplicate_hits_with_query(hits, "")
}

pub(crate) fn deduplicate_hits_with_query(hits: Vec<SearchHit>, query: &str) -> Vec<SearchHit> {
    // Key: (source_numeric_id, source_path_numeric_id, conversation_id-or-title,
    //       line_number, created_at, content_hash) -> index in deduped.
    // Include message-level identity so repeated identical content in the same
    // session remains visible as distinct hits when it came from different messages.
    // When conversation_id exists, it is authoritative and title drift must not
    // split or merge hits incorrectly.
    let mut source_ids: HashMap<String, u32> = HashMap::new();
    let mut path_ids: HashMap<String, u32> = HashMap::new();
    let mut title_ids: HashMap<String, u32> = HashMap::new();
    let mut next_source_id: u32 = 0;
    let mut next_path_id: u32 = 0;
    let mut next_title_id: u32 = 0;
    type DedupKey = (
        u32,
        u32,
        Option<i64>,
        Option<u32>,
        Option<usize>,
        Option<i64>,
        u64,
    );

    let mut seen: HashMap<DedupKey, usize> = HashMap::new();
    let mut deduped: Vec<SearchHit> = Vec::new();

    for hit in hits {
        if hit_is_noise(&hit, query) {
            continue;
        }

        // Include normalized source identity AND source_path in the key so different
        // sessions keep their results while local provenance drift still coalesces.
        let normalized_source_id = normalized_search_hit_source_id(&hit);
        let source_key = if let Some(id) = source_ids.get(normalized_source_id.as_str()) {
            *id
        } else {
            let id = next_source_id;
            next_source_id = next_source_id.saturating_add(1);
            source_ids.insert(normalized_source_id, id);
            id
        };
        let path_key = if let Some(id) = path_ids.get(hit.source_path.as_str()) {
            *id
        } else {
            let id = next_path_id;
            next_path_id = next_path_id.saturating_add(1);
            path_ids.insert(hit.source_path.clone(), id);
            id
        };
        let title_key = if hit.conversation_id.is_some() {
            None
        } else {
            let normalized_title = hit.title.trim();
            Some(if let Some(id) = title_ids.get(normalized_title) {
                *id
            } else {
                let id = next_title_id;
                next_title_id = next_title_id.saturating_add(1);
                title_ids.insert(normalized_title.to_string(), id);
                id
            })
        };
        let key = (
            source_key,
            path_key,
            hit.conversation_id,
            title_key,
            hit.line_number,
            hit.created_at,
            hit.content_hash,
        );

        if let Some(&existing_idx) = seen.get(&key) {
            // If existing hit has lower score, replace it
            if deduped[existing_idx].score < hit.score {
                deduped[existing_idx] = hit;
            }
            // Otherwise keep existing (higher score)
        } else {
            seen.insert(key, deduped.len());
            deduped.push(hit);
        }
    }

    deduped
}

fn should_try_wildcard_fallback(
    returned_hits: usize,
    limit: usize,
    offset: usize,
    sparse_threshold: usize,
) -> bool {
    if offset != 0 {
        return false;
    }

    let effective_sparse_threshold = if limit == 0 {
        sparse_threshold
    } else {
        sparse_threshold.min(limit)
    };

    returned_hits < effective_sparse_threshold
}

fn should_skip_automatic_wildcard_fallback_for_long_zero_hit_query(
    query: &str,
    returned_hits: usize,
) -> bool {
    if returned_hits != 0 {
        return false;
    }

    for token in normalize_phrase_terms(query) {
        if token.chars().count() > AUTOMATIC_WILDCARD_FALLBACK_MAX_TOKEN_CHARS {
            return true;
        }
    }

    false
}

fn snippet_from_preview_without_full_content(
    field_mask: FieldMask,
    stored_preview: &str,
    query: &str,
) -> Option<String> {
    if field_mask.needs_content() || !field_mask.wants_snippet() || stored_preview.is_empty() {
        return None;
    }

    cached_prefix_snippet(stored_preview, query, 160)
}

fn stored_preview_is_complete_content(stored_preview: &str) -> bool {
    // The preview builder appends U+2026 only when truncating. A real message
    // ending with that character becomes a conservative false negative here.
    !stored_preview.is_empty() && !stored_preview.ends_with('…')
}

impl SearchClient {
    pub fn open(index_path: &Path, db_path: Option<&Path>) -> Result<Option<Self>> {
        Self::open_with_options(index_path, db_path, SearchClientOptions::default())
    }

    pub fn open_with_options(
        index_path: &Path,
        db_path: Option<&Path>,
        options: SearchClientOptions,
    ) -> Result<Option<Self>> {
        let tantivy = fs_cass_open_search_reader(index_path, ReloadPolicy::Manual).ok();
        let client_id = SEARCH_CLIENT_INSTANCE_COUNTER.fetch_add(1, Ordering::Relaxed);
        let cache_namespace = format!(
            "v{}|schema:{}|client:{}|index:{}",
            CACHE_KEY_VERSION,
            FS_CASS_SCHEMA_HASH,
            client_id,
            index_path.display()
        );
        let federated_readers = if tantivy.is_none() {
            crate::search::tantivy::open_federated_search_readers(index_path, ReloadPolicy::Manual)
                .ok()
                .flatten()
                .filter(|readers| !readers.is_empty())
                .map(|readers| {
                    Arc::new(
                        readers
                            .into_iter()
                            .map(|(reader, fields)| FederatedIndexReader { reader, fields })
                            .collect::<Vec<_>>(),
                    )
                })
        } else {
            None
        };

        let sqlite_path = db_path.map(Path::to_path_buf).filter(|path| path.exists());

        if tantivy.is_none() && federated_readers.is_none() && sqlite_path.is_some() {
            tracing::warn!(
                index_path = %index_path.display(),
                "Tantivy search index not found or incompatible. \
                 Search results will be degraded. \
                 Run `cass index --full` to rebuild the index."
            );
        }

        if tantivy.is_none() && federated_readers.is_none() && sqlite_path.is_none() {
            return Ok(None);
        }

        let reload_epoch = Arc::new(AtomicU64::new(0));
        let metrics = Metrics::default();

        let warm_pair = if options.enable_warm
            && let Some((reader, fields)) = &tantivy
        {
            maybe_spawn_warm_worker(
                reader.clone(),
                *fields,
                reload_epoch.clone(),
                metrics.clone(),
            )
        } else {
            None
        };

        if let Some(readers) = &federated_readers {
            FEDERATED_SEARCH_READERS
                .write()
                .insert(cache_namespace.clone(), Arc::clone(readers));
        } else {
            FEDERATED_SEARCH_READERS.write().remove(&cache_namespace);
        }

        Ok(Some(Self {
            reader: tantivy,
            sqlite: Mutex::new(None),
            sqlite_path,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: options.enable_reload,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch,
            warm_tx: warm_pair.as_ref().map(|(tx, _)| tx.clone()),
            _warm_handle: warm_pair.map(|(_, h)| h),
            metrics,
            cache_namespace,
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        }))
    }

    fn sqlite_guard(&self) -> Result<std::sync::MutexGuard<'_, Option<SendConnection>>> {
        let mut guard = self
            .sqlite
            .lock()
            .map_err(|_| anyhow!("sqlite lock poisoned"))?;

        if guard.is_none()
            && let Some(path) = &self.sqlite_path
        {
            match open_search_hydration_sqlite(path, std::time::Duration::from_secs(1)) {
                Ok(conn) => {
                    *guard = Some(SendConnection(conn));
                }
                Err(err) => {
                    tracing::debug!(
                        error = %err,
                        path = %path.display(),
                        "readonly sqlite open failed for search client"
                    );
                }
            }
        }

        Ok(guard)
    }

    pub fn search(
        &self,
        query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        field_mask: FieldMask,
    ) -> Result<Vec<SearchHit>> {
        // NFC-normalize early so every downstream consumer (Tantivy query
        // builder, sanitizer, FTS5 fallback) sees consistent Unicode form
        // matching the NFC-indexed content.
        use unicode_normalization::UnicodeNormalization;
        let query: String = query.nfc().collect();
        let query: &str = &query;
        let sanitized = nfc_sanitize_query(query);
        let field_mask = effective_field_mask(field_mask);
        let limit = if limit == 0 {
            self.total_docs().min(no_limit_result_cap()).max(1)
        } else {
            limit
        };
        let can_use_cache =
            field_mask.allows_cache() && (field_mask.needs_content() || field_mask.wants_snippet());

        // Invalidate prefix cache if the index has been updated since last search.
        // This must happen BEFORE the cache check below to avoid serving stale results.
        if let Some((reader, _)) = &self.reader {
            self.maybe_reload_reader(reader)?;
            let searcher = self.searcher_for_thread(reader);
            self.track_generation(searcher.generation().generation_id());
        } else if let Some(readers) = self.federated_readers()
            && let Some(signature) = self.maybe_reload_federated_readers(readers.as_ref())?
        {
            self.track_generation(signature);
        }

        // Fast path: reuse cached prefix when user is typing forward (offset 0 only).
        // Only use cache for simple queries (no wildcards, no boolean operators) because
        // the cache matching logic enforces strict prefix AND semantics which is incorrect
        // for suffixes, substrings, OR, NOT, or phrases.
        if can_use_cache
            && offset == 0
            && !query.contains('*')
            && !fs_cass_has_boolean_operators(query)
        {
            self.maybe_schedule_adaptive_query_prewarm(&sanitized, &filters);
            if let Some(cached) = self.cached_prefix_hits(&sanitized, &filters) {
                // Opt 2.4: Pre-compute lowercase query terms once, reuse for all hits
                let query_terms = QueryTermsLower::from_query(&sanitized);
                let mut filtered: Vec<SearchHit> = cached
                    .into_iter()
                    .filter(|h| hit_matches_query_cached_precomputed(h, &query_terms))
                    .map(|c| c.hit.clone())
                    .collect();
                if filtered.len() >= limit {
                    filtered.truncate(limit);
                    self.metrics.inc_cache_hits();
                    self.maybe_log_cache_metrics("hit");
                    return Ok(filtered);
                }
                // Cache had entries but not enough to satisfy limit - shortfall, not miss
                self.metrics.inc_cache_shortfall();
                self.maybe_log_cache_metrics("shortfall");
            } else {
                // No cached prefix at all - this is the actual miss
                self.metrics.inc_cache_miss();
                self.maybe_log_cache_metrics("miss");
            }
        }

        // Adaptive fetch sizing: start at 2x target to reduce common-case work,
        // retry at 3x only when deduplication causes shortfall.
        // We always fetch from 0 to preserve global deduplication correctness.
        let target_hits = offset.saturating_add(limit);
        let initial_fetch_limit = if target_hits <= 16 {
            target_hits.saturating_mul(2)
        } else {
            // Larger pages benefit from a lower first-pass over-fetch.
            // Retry logic below preserves correctness on duplicate-heavy corpora.
            target_hits.saturating_mul(3).div_ceil(2)
        };
        let session_path_filter_active = !filters.session_paths.is_empty();
        let fallback_fetch_limit = if session_path_filter_active {
            self.total_docs()
                .min(no_limit_result_cap())
                .max(target_hits.saturating_mul(3))
                .max(1)
        } else {
            target_hits.saturating_mul(3)
        };

        // Tantivy is the primary high-performance engine.
        if let Some((reader, fields)) = &self.reader {
            tracing::info!(
                backend = "tantivy",
                query = sanitized,
                limit = initial_fetch_limit,
                offset = 0,
                "search_start"
            );
            let (hits, tantivy_total_count) = self.search_tantivy(
                reader,
                fields,
                query,
                &sanitized,
                filters.clone(),
                initial_fetch_limit,
                0, // Always fetch from 0 for global dedup
                field_mask,
            )?;
            if let Ok(mut tc) = self.last_tantivy_total_count.lock() {
                *tc = Some(tantivy_total_count);
            }
            if !hits.is_empty() {
                let initial_hit_count = hits.len();
                let page_hits = |raw_hits: Vec<SearchHit>| {
                    self.postprocess_hits_page(raw_hits, &sanitized, &filters, limit, offset)
                };

                let (mut deduped_len, mut paged_hits) = page_hits(hits);

                let needs_retry = deduped_len < target_hits
                    && initial_hit_count == initial_fetch_limit
                    && initial_fetch_limit < fallback_fetch_limit;

                if needs_retry {
                    tracing::debug!(
                        query = sanitized,
                        target_hits,
                        deduped_len,
                        initial_fetch_limit,
                        fallback_fetch_limit,
                        session_path_filter_active,
                        "retrying lexical fetch due to dedup or session-path shortfall"
                    );
                    let (retry_hits, retry_total_count) = self.search_tantivy(
                        reader,
                        fields,
                        query,
                        &sanitized,
                        filters.clone(),
                        fallback_fetch_limit,
                        0,
                        field_mask,
                    )?;
                    if let Ok(mut tc) = self.last_tantivy_total_count.lock() {
                        *tc = Some(retry_total_count);
                    }
                    if !retry_hits.is_empty() {
                        (deduped_len, paged_hits) = page_hits(retry_hits);
                    }
                }

                tracing::trace!(
                    query = sanitized,
                    target_hits,
                    deduped_len,
                    returned = paged_hits.len(),
                    "lexical fetch complete"
                );

                if can_use_cache && offset == 0 {
                    self.put_cache(&sanitized, &filters, &paged_hits);
                }
                return Ok(paged_hits);
            }
            tracing::debug!(
                query = sanitized,
                "tantivy returned zero hits; skipping sqlite fallback because tantivy is authoritative when available"
            );
            return Ok(Vec::new());
        } else if let Some(readers) = self.federated_readers() {
            tracing::info!(
                backend = "tantivy-federated",
                query = sanitized,
                limit = initial_fetch_limit,
                offset = 0,
                shards = readers.len(),
                "search_start"
            );
            let (hits, tantivy_total_count) = self.search_tantivy_federated(
                readers.as_ref(),
                query,
                &sanitized,
                filters.clone(),
                initial_fetch_limit,
                field_mask,
            )?;
            if let Ok(mut tc) = self.last_tantivy_total_count.lock() {
                *tc = Some(tantivy_total_count);
            }
            if !hits.is_empty() {
                let initial_hit_count = hits.len();
                let page_hits = |raw_hits: Vec<SearchHit>| {
                    self.postprocess_hits_page(raw_hits, &sanitized, &filters, limit, offset)
                };

                let (mut deduped_len, mut paged_hits) = page_hits(hits);
                let expected_federated_capacity = initial_fetch_limit.saturating_mul(readers.len());
                let federated_initial_capacity_reached = if session_path_filter_active {
                    initial_hit_count >= initial_fetch_limit.min(expected_federated_capacity)
                } else {
                    initial_hit_count == expected_federated_capacity
                };
                let needs_retry = deduped_len < target_hits
                    && federated_initial_capacity_reached
                    && initial_fetch_limit < fallback_fetch_limit;

                if needs_retry {
                    tracing::debug!(
                        query = sanitized,
                        target_hits,
                        deduped_len,
                        initial_fetch_limit,
                        fallback_fetch_limit,
                        shards = readers.len(),
                        session_path_filter_active,
                        "retrying federated lexical fetch due to dedup or session-path shortfall"
                    );
                    let (retry_hits, retry_total_count) = self.search_tantivy_federated(
                        readers.as_ref(),
                        query,
                        &sanitized,
                        filters.clone(),
                        fallback_fetch_limit,
                        field_mask,
                    )?;
                    if let Ok(mut tc) = self.last_tantivy_total_count.lock() {
                        *tc = Some(retry_total_count);
                    }
                    if !retry_hits.is_empty() {
                        (deduped_len, paged_hits) = page_hits(retry_hits);
                    }
                }

                tracing::trace!(
                    query = sanitized,
                    target_hits,
                    deduped_len,
                    returned = paged_hits.len(),
                    shards = readers.len(),
                    "federated lexical fetch complete"
                );

                if can_use_cache && offset == 0 {
                    self.put_cache(&sanitized, &filters, &paged_hits);
                }
                return Ok(paged_hits);
            }
            tracing::debug!(
                query = sanitized,
                shards = readers.len(),
                "federated tantivy returned zero hits; skipping sqlite fallback because tantivy is authoritative when available"
            );
            return Ok(Vec::new());
        }

        // Skip SQLite fallback when the query contains leading/internal wildcards that
        // FTS5 cannot parse (e.g., "*handler" or "f*o").
        // We ALLOW trailing wildcards ("foo*") as FTS5 supports prefix matching.
        let unsupported_wildcards = sanitized.split_whitespace().any(|t| {
            let core = t.trim_end_matches('*');
            core.contains('*') // Any star remaining after trimming end is unsupported (leading or internal)
        });

        if unsupported_wildcards {
            return Ok(Vec::new());
        }

        let has_sqlite_backend = {
            let sqlite_guard = self
                .sqlite
                .lock()
                .map_err(|_| anyhow!("sqlite lock poisoned"))?;
            sqlite_guard.is_some() || self.sqlite_path.is_some()
        };

        if has_sqlite_backend {
            tracing::info!(
                backend = "sqlite-fts5",
                query = sanitized,
                limit = fallback_fetch_limit,
                offset = 0,
                "search_start"
            );
            let hits = self.search_sqlite_fts5(
                self.sqlite_path
                    .as_deref()
                    .unwrap_or_else(|| Path::new(":memory:")),
                query,
                filters.clone(),
                fallback_fetch_limit,
                0, // Always fetch from 0 for global dedup
                field_mask,
            )?;
            let (_, paged_hits) =
                self.postprocess_hits_page(hits, &sanitized, &filters, limit, offset);

            if can_use_cache && offset == 0 {
                self.put_cache(&sanitized, &filters, &paged_hits);
            }
            return Ok(paged_hits);
        }

        tracing::info!(backend = "none", query = query, "search_start");
        Ok(Vec::new())
    }

    pub fn set_semantic_context(
        &self,
        embedder: Arc<dyn Embedder>,
        fs_semantic_index: VectorIndex,
        filter_maps: SemanticFilterMaps,
        roles: Option<HashSet<u8>>,
        ann_path: Option<PathBuf>,
    ) -> Result<()> {
        self.set_semantic_indexes_context(
            embedder,
            vec![fs_semantic_index],
            filter_maps,
            roles,
            ann_path,
        )
    }

    pub fn set_semantic_indexes_context(
        &self,
        embedder: Arc<dyn Embedder>,
        fs_semantic_indexes: Vec<VectorIndex>,
        filter_maps: SemanticFilterMaps,
        roles: Option<HashSet<u8>>,
        ann_path: Option<PathBuf>,
    ) -> Result<()> {
        if fs_semantic_indexes.is_empty() {
            bail!("semantic context requires at least one vector index");
        }

        let fs_semantic_indexes = fs_semantic_indexes
            .into_iter()
            .map(|index| {
                let embedder_id = index.embedder_id().to_string();
                let dimension = index.dimension();
                if embedder_id != embedder.id() {
                    bail!(
                        "embedder mismatch: index uses {}, embedder is {}",
                        embedder_id,
                        embedder.id()
                    );
                }
                if dimension != embedder.dimension() {
                    bail!(
                        "embedder dimension mismatch: index uses {}, embedder is {}",
                        dimension,
                        embedder.dimension()
                    );
                }
                Ok(Arc::new(index))
            })
            .collect::<Result<Vec<_>>>()?;
        let fs_semantic_index = Arc::clone(&fs_semantic_indexes[0]);
        let shard_count = fs_semantic_indexes.len();
        let ann_path = if shard_count == 1 { ann_path } else { None };
        let embedder_id = fs_semantic_index.embedder_id().to_string();
        let dimension = fs_semantic_index.dimension();
        let fs_semantic_indexes = Arc::new(fs_semantic_indexes);

        let capacity = NonZeroUsize::new(100).ok_or_else(|| anyhow!("invalid cache size"))?;
        let context_token = Arc::new(());
        let mut state_guard = self
            .semantic
            .lock()
            .map_err(|_| anyhow!("semantic lock poisoned"))?;
        *state_guard = Some(SemanticSearchState {
            context_token,
            embedder,
            fs_semantic_index,
            fs_semantic_indexes,
            fs_ann_index: None,
            ann_path,
            fs_in_memory_two_tier_index: None,
            in_memory_two_tier_unavailable: InMemoryTwoTierUnavailable::default(),
            progressive_context: None,
            progressive_context_unavailable: false,
            filter_maps,
            roles,
            query_cache: QueryCache::new(embedder_id.as_str(), capacity),
        });
        if shard_count > 1 {
            tracing::info!(
                shard_count,
                dimension,
                embedder = embedder_id,
                "semantic search context loaded sharded vector generation"
            );
        }
        Ok(())
    }

    pub fn clear_semantic_context(&self) -> Result<()> {
        let mut guard = self
            .semantic
            .lock()
            .map_err(|_| anyhow!("semantic lock poisoned"))?;
        *guard = None;
        Ok(())
    }

    fn semantic_context_matches(&self, context_token: &Arc<()>) -> Result<bool> {
        let guard = self
            .semantic
            .lock()
            .map_err(|_| anyhow!("semantic lock poisoned"))?;
        Ok(guard
            .as_ref()
            .is_some_and(|state| Arc::ptr_eq(&state.context_token, context_token)))
    }

    fn semantic_query_embedding(&self, canonical: &str) -> Result<SemanticQueryEmbedding> {
        loop {
            let (embedder, context_token) = {
                let mut guard = self
                    .semantic
                    .lock()
                    .map_err(|_| anyhow!("semantic lock poisoned"))?;
                let state = guard.as_mut().ok_or_else(|| {
                    anyhow!("semantic search unavailable (no embedder or vector index)")
                })?;
                if let Some(hit) = state
                    .query_cache
                    .get_cached(state.embedder.as_ref(), canonical)
                {
                    return Ok(SemanticQueryEmbedding {
                        context_token: Arc::clone(&state.context_token),
                        vector: hit,
                    });
                }
                (
                    Arc::clone(&state.embedder),
                    Arc::clone(&state.context_token),
                )
            };

            let embedding = embedder
                .embed_sync(canonical)
                .map_err(|e| anyhow!("embedding failed: {e}"))?;

            let mut guard = self
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard.as_mut().ok_or_else(|| {
                anyhow!("semantic search unavailable (no embedder or vector index)")
            })?;
            if !Arc::ptr_eq(&state.context_token, &context_token) {
                continue;
            }
            if let Some(hit) = state
                .query_cache
                .get_cached(state.embedder.as_ref(), canonical)
            {
                return Ok(SemanticQueryEmbedding {
                    context_token,
                    vector: hit,
                });
            }
            state
                .query_cache
                .store(state.embedder.as_ref(), canonical, embedding.clone());
            return Ok(SemanticQueryEmbedding {
                context_token,
                vector: embedding,
            });
        }
    }

    fn in_memory_two_tier_index(
        &self,
        tier_mode: SemanticTierMode,
    ) -> Result<Option<Arc<FsInMemoryTwoTierIndex>>> {
        loop {
            let (ann_path, embedder_id, context_token) = {
                let mut guard = self
                    .semantic
                    .lock()
                    .map_err(|_| anyhow!("semantic lock poisoned"))?;
                let state = guard.as_mut().ok_or_else(|| {
                    anyhow!("semantic search unavailable (no embedder or vector index)")
                })?;
                if let Some(index) = state.fs_in_memory_two_tier_index.as_ref()
                    && two_tier_index_supports_mode(index.as_ref(), tier_mode)
                {
                    return Ok(Some(Arc::clone(index)));
                }
                if state
                    .in_memory_two_tier_unavailable
                    .is_known_unavailable(tier_mode)
                {
                    return Ok(None);
                }
                (
                    state.ann_path.clone(),
                    state.embedder.id().to_string(),
                    Arc::clone(&state.context_token),
                )
            };

            let index = build_in_memory_two_tier_index(ann_path.clone(), &embedder_id, tier_mode);

            let mut guard = self
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard.as_mut().ok_or_else(|| {
                anyhow!("semantic search unavailable (no embedder or vector index)")
            })?;
            if let Some(existing) = state.fs_in_memory_two_tier_index.as_ref()
                && two_tier_index_supports_mode(existing.as_ref(), tier_mode)
            {
                return Ok(Some(Arc::clone(existing)));
            }
            if !Arc::ptr_eq(&state.context_token, &context_token) {
                continue;
            }
            let Some(index) = index else {
                state
                    .in_memory_two_tier_unavailable
                    .mark_unavailable(tier_mode);
                return Ok(None);
            };
            if !two_tier_index_supports_mode(index.as_ref(), tier_mode) {
                state
                    .in_memory_two_tier_unavailable
                    .mark_unavailable(tier_mode);
                return Ok(None);
            }
            state.fs_in_memory_two_tier_index = Some(Arc::clone(&index));
            if index.has_quality_index() {
                state.in_memory_two_tier_unavailable = InMemoryTwoTierUnavailable::default();
            } else {
                state.in_memory_two_tier_unavailable.fast_only = false;
            }
            return Ok(Some(index));
        }
    }

    fn ann_index(&self) -> Result<Arc<FsHnswIndex>> {
        loop {
            let (ann_path, fs_semantic_index) = {
                let mut guard = self
                    .semantic
                    .lock()
                    .map_err(|_| anyhow!("semantic lock poisoned"))?;
                let state = guard.as_mut().ok_or_else(|| {
                    anyhow!("semantic search unavailable (no embedder or vector index)")
                })?;
                if let Some(index) = state.fs_ann_index.as_ref() {
                    return Ok(Arc::clone(index));
                }
                let ann_path = state.ann_path.clone().ok_or_else(|| {
                    anyhow!(
                        "approximate search unavailable: HNSW index missing (run 'cass index --semantic --build-hnsw')"
                    )
                })?;
                (ann_path, Arc::clone(&state.fs_semantic_index))
            };

            let ann = Arc::new(open_fs_semantic_ann_index(
                fs_semantic_index.as_ref(),
                &ann_path,
            )?);

            let mut guard = self
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard.as_mut().ok_or_else(|| {
                anyhow!("semantic search unavailable (no embedder or vector index)")
            })?;
            if let Some(existing) = state.fs_ann_index.as_ref() {
                return Ok(Arc::clone(existing));
            }
            if state.ann_path.as_ref() != Some(&ann_path)
                || !Arc::ptr_eq(&state.fs_semantic_index, &fs_semantic_index)
            {
                continue;
            }
            state.fs_ann_index = Some(Arc::clone(&ann));
            return Ok(ann);
        }
    }

    fn collapse_semantic_results(
        best_by_message: HashMap<u64, VectorSearchResult>,
        fetch_limit: usize,
    ) -> Vec<VectorSearchResult> {
        let mut collapsed: Vec<VectorSearchResult> = best_by_message.into_values().collect();
        collapsed.sort_by(|a, b| {
            b.score
                .total_cmp(&a.score)
                .then_with(|| a.message_id.cmp(&b.message_id))
        });
        if collapsed.len() > fetch_limit {
            collapsed.truncate(fetch_limit);
        }
        collapsed
    }

    fn semantic_exact_candidate_limit(fetch_limit: usize, record_count: usize) -> usize {
        fetch_limit
            .saturating_mul(SEMANTIC_EXACT_CHUNK_OVERFETCH_MULTIPLIER)
            .max(fetch_limit)
            .min(record_count)
    }

    fn semantic_window_may_omit_competitor(
        collapsed: &[VectorSearchResult],
        fetch_limit: usize,
        max_omitted_score: Option<f32>,
    ) -> bool {
        if fetch_limit == 0 {
            return false;
        }
        let Some(max_omitted_score) = max_omitted_score else {
            return false;
        };
        if collapsed.len() < fetch_limit {
            return true;
        }
        let Some(last_in_requested_window) = collapsed.get(fetch_limit - 1) else {
            return true;
        };
        !last_in_requested_window
            .score
            .total_cmp(&max_omitted_score)
            .is_gt()
    }

    fn record_fs_semantic_hit(
        best_by_message: &mut HashMap<u64, VectorSearchResult>,
        hit: &FsVectorHit,
    ) {
        let Some(parsed) = parse_semantic_doc_id(&hit.doc_id) else {
            return;
        };
        best_by_message
            .entry(parsed.message_id)
            .and_modify(|entry| {
                if hit.score > entry.score {
                    entry.score = hit.score;
                    entry.chunk_idx = parsed.chunk_idx;
                }
            })
            .or_insert(VectorSearchResult {
                message_id: parsed.message_id,
                chunk_idx: parsed.chunk_idx,
                score: hit.score,
            });
    }

    fn search_exact_semantic_indexes(
        context: &SemanticCandidateContext,
        embedding: &[f32],
        fetch_limit: usize,
        fs_filter: Option<&dyn FsSearchFilter>,
    ) -> Result<(Vec<VectorSearchResult>, SemanticCandidateRetryState)> {
        if context.fs_semantic_indexes.len() == 1 {
            let record_count = context.fs_semantic_index.record_count();
            let candidate_limit = Self::semantic_exact_candidate_limit(fetch_limit, record_count);
            let fs_hits = context
                .fs_semantic_index
                .search_top_k(embedding, candidate_limit, fs_filter)
                .map_err(|err| anyhow!("frankensearch semantic search failed: {err}"))?;
            let mut best_by_message = HashMap::with_capacity(fs_hits.len());
            for hit in &fs_hits {
                Self::record_fs_semantic_hit(&mut best_by_message, hit);
            }
            let collapsed = Self::collapse_semantic_results(best_by_message, candidate_limit);
            let has_more_candidates =
                fs_hits.len() >= candidate_limit && candidate_limit < record_count;
            let max_omitted_score = if has_more_candidates {
                fs_hits.last().map(|hit| hit.score)
            } else {
                None
            };
            let exact_window_may_omit_competitor = Self::semantic_window_may_omit_competitor(
                &collapsed,
                fetch_limit,
                max_omitted_score,
            );
            return Ok((
                collapsed,
                SemanticCandidateRetryState {
                    has_more_candidates,
                    exact_window_may_omit_competitor,
                },
            ));
        }

        let mut best_by_message = HashMap::new();
        let mut raw_hits = 0usize;
        let mut max_omitted_score: Option<f32> = None;
        let mut has_more_candidates = false;
        for index in context.fs_semantic_indexes.iter() {
            let shard_record_count = index.record_count();
            // Search chunks, then collapse by message. A message can have many
            // high-scoring chunks, so per-shard top-k chunks alone is not a
            // proof of per-message top-k. Use a bounded overfetch window and
            // retry only when the omitted-score bound can still beat the last
            // collapsed message in the requested window.
            let shard_limit = Self::semantic_exact_candidate_limit(fetch_limit, shard_record_count);
            if shard_limit == 0 {
                continue;
            }
            let fs_hits = index
                .search_top_k(embedding, shard_limit, fs_filter)
                .map_err(|err| anyhow!("frankensearch sharded semantic search failed: {err}"))?;
            if fs_hits.len() >= shard_limit
                && shard_limit < shard_record_count
                && let Some(last_hit) = fs_hits.last()
            {
                has_more_candidates = true;
                max_omitted_score = Some(
                    max_omitted_score
                        .map(|current| current.max(last_hit.score))
                        .unwrap_or(last_hit.score),
                );
            }
            raw_hits = raw_hits.saturating_add(fs_hits.len());
            best_by_message.reserve(fs_hits.len());
            for hit in &fs_hits {
                Self::record_fs_semantic_hit(&mut best_by_message, hit);
            }
        }
        let candidate_return_limit = Self::semantic_exact_candidate_limit(fetch_limit, raw_hits);
        let collapsed = Self::collapse_semantic_results(best_by_message, candidate_return_limit);
        let exact_window_may_omit_competitor =
            Self::semantic_window_may_omit_competitor(&collapsed, fetch_limit, max_omitted_score);
        tracing::debug!(
            shard_count = context.fs_semantic_indexes.len(),
            raw_hits,
            returned = collapsed.len(),
            "semantic sharded exact merge complete"
        );
        Ok((
            collapsed,
            SemanticCandidateRetryState {
                has_more_candidates,
                exact_window_may_omit_competitor,
            },
        ))
    }

    fn search_semantic_candidates(
        &self,
        context: &SemanticCandidateContext,
        embedding: &[f32],
        filters: &SearchFilters,
        request: SemanticCandidateSearchRequest<'_>,
    ) -> Result<(
        Vec<VectorSearchResult>,
        SemanticCandidateRetryState,
        Option<crate::search::ann_index::AnnSearchStats>,
    )> {
        let mut semantic_filter =
            SemanticFilter::from_search_filters(filters, &context.filter_maps)?;
        if let Some(roles) = context.roles.clone() {
            semantic_filter = semantic_filter.with_roles(Some(roles));
        }

        if request.tier_mode.wants_two_tier() && !request.approximate {
            let fs_filter = semantic_filter_as_search_filter(&semantic_filter);
            if let Some(two_tier_index) = request.in_memory_two_tier_index {
                let config = request.tier_mode.to_frankensearch_config();
                let searcher = FsSyncTwoTierSearcher::new(Arc::clone(two_tier_index), config);
                let (tier_hits, metrics) = searcher
                    .search_collect_with_filter(embedding, request.fetch_limit, fs_filter)
                    .map_err(|err| {
                        anyhow!("frankensearch two-tier semantic search failed: {err}")
                    })?;

                tracing::debug!(
                    tier_mode = ?request.tier_mode,
                    phase1_ms = metrics.phase1_total_ms,
                    phase2_ms = metrics.phase2_total_ms,
                    skip_reason = ?metrics.skip_reason,
                    returned = tier_hits.len(),
                    "semantic two-tier search executed"
                );

                let mut best_by_message: HashMap<u64, VectorSearchResult> =
                    HashMap::with_capacity(tier_hits.len());
                for hit in tier_hits.iter() {
                    let Some(parsed) = parse_semantic_doc_id(&hit.doc_id) else {
                        continue;
                    };
                    best_by_message
                        .entry(parsed.message_id)
                        .and_modify(|entry| {
                            if hit.score > entry.score {
                                entry.score = hit.score;
                                entry.chunk_idx = parsed.chunk_idx;
                            }
                        })
                        .or_insert(VectorSearchResult {
                            message_id: parsed.message_id,
                            chunk_idx: parsed.chunk_idx,
                            score: hit.score,
                        });
                }

                return Ok((
                    Self::collapse_semantic_results(best_by_message, request.fetch_limit),
                    SemanticCandidateRetryState {
                        has_more_candidates: tier_hits.len() >= request.fetch_limit,
                        exact_window_may_omit_competitor: false,
                    },
                    None,
                ));
            }

            tracing::debug!(
                tier_mode = ?request.tier_mode,
                "two-tier semantic unavailable; falling back to exact single-tier search"
            );

            let fs_filter = semantic_filter_as_search_filter(&semantic_filter);
            let (results, truncated) = Self::search_exact_semantic_indexes(
                context,
                embedding,
                request.fetch_limit,
                fs_filter,
            )?;
            return Ok((results, truncated, None));
        }

        if request.approximate {
            if request.tier_mode.wants_two_tier() {
                tracing::debug!(
                    tier_mode = ?request.tier_mode,
                    "approximate search requested; bypassing two-tier mode"
                );
            }

            let ann = request
                .ann_index
                .ok_or_else(|| anyhow!("HNSW index failed to initialize"))?;
            let candidate = request
                .fetch_limit
                .saturating_mul(ANN_CANDIDATE_MULTIPLIER)
                .max(request.fetch_limit);
            let ef = FS_HNSW_DEFAULT_EF_SEARCH.max(candidate);
            let (ann_results, search_stats) =
                ann.knn_search_with_stats(embedding, candidate, ef)
                    .map_err(|err| anyhow!("frankensearch approximate search failed: {err}"))?;
            let ann_stats = Some(crate::search::ann_index::AnnSearchStats {
                index_size: search_stats.index_size,
                dimension: search_stats.dimension,
                ef_search: search_stats.ef_search,
                k_requested: search_stats.k_requested,
                k_returned: search_stats.k_returned,
                search_time_us: search_stats.search_time_us,
                estimated_recall: search_stats.estimated_recall as f32,
                is_approximate: search_stats.is_approximate,
            });

            let fs_filter = semantic_filter_as_search_filter(&semantic_filter);

            let mut best_by_message: HashMap<u64, VectorSearchResult> =
                HashMap::with_capacity(ann_results.len());
            for hit in ann_results.iter() {
                if let Some(filter) = fs_filter
                    && !filter.matches(&hit.doc_id, None)
                {
                    continue;
                }
                let Some(parsed) = parse_semantic_doc_id(&hit.doc_id) else {
                    continue;
                };
                best_by_message
                    .entry(parsed.message_id)
                    .and_modify(|entry| {
                        if hit.score > entry.score {
                            entry.score = hit.score;
                            entry.chunk_idx = parsed.chunk_idx;
                        }
                    })
                    .or_insert(VectorSearchResult {
                        message_id: parsed.message_id,
                        chunk_idx: parsed.chunk_idx,
                        score: hit.score,
                    });
            }

            return Ok((
                Self::collapse_semantic_results(best_by_message, request.fetch_limit),
                SemanticCandidateRetryState {
                    has_more_candidates: ann_results.len() >= candidate,
                    exact_window_may_omit_competitor: false,
                },
                ann_stats,
            ));
        }

        let fs_filter = semantic_filter_as_search_filter(&semantic_filter);
        let (results, truncated) = Self::search_exact_semantic_indexes(
            context,
            embedding,
            request.fetch_limit,
            fs_filter,
        )?;
        Ok((results, truncated, None))
    }

    pub fn can_progressively_refine(&self) -> bool {
        self.progressive_context()
            .map(|context| {
                context.as_ref().is_some_and(|ctx| {
                    ctx.quality_embedder.is_some() && ctx.index.has_quality_index()
                })
            })
            .unwrap_or(false)
    }

    fn progressive_context(&self) -> Result<Option<Arc<ProgressiveTwoTierContext>>> {
        loop {
            let (ann_path, embedder, context_token) = {
                let mut guard = self
                    .semantic
                    .lock()
                    .map_err(|_| anyhow!("semantic lock poisoned"))?;
                let state = guard.as_mut().ok_or_else(|| {
                    anyhow!("semantic search unavailable (no embedder or vector index)")
                })?;
                if let Some(context) = state.progressive_context.as_ref() {
                    return Ok(Some(Arc::clone(context)));
                }
                if state.progressive_context_unavailable {
                    return Ok(None);
                }
                (
                    state.ann_path.clone(),
                    Arc::clone(&state.embedder),
                    Arc::clone(&state.context_token),
                )
            };

            let context = match self.build_progressive_context(
                ann_path.clone(),
                embedder,
                Arc::clone(&context_token),
            ) {
                Ok(context) => context,
                Err(err) => {
                    let mut guard = self
                        .semantic
                        .lock()
                        .map_err(|_| anyhow!("semantic lock poisoned"))?;
                    let state = guard.as_mut().ok_or_else(|| {
                        anyhow!("semantic search unavailable (no embedder or vector index)")
                    })?;
                    if let Some(existing) = state.progressive_context.as_ref() {
                        return Ok(Some(Arc::clone(existing)));
                    }
                    if !Arc::ptr_eq(&state.context_token, &context_token) {
                        continue;
                    }
                    return Err(err);
                }
            };

            let Some(context) = context else {
                let mut guard = self
                    .semantic
                    .lock()
                    .map_err(|_| anyhow!("semantic lock poisoned"))?;
                let state = guard.as_mut().ok_or_else(|| {
                    anyhow!("semantic search unavailable (no embedder or vector index)")
                })?;
                if let Some(existing) = state.progressive_context.as_ref() {
                    return Ok(Some(Arc::clone(existing)));
                }
                if !Arc::ptr_eq(&state.context_token, &context_token) {
                    continue;
                }
                state.progressive_context_unavailable = true;
                return Ok(None);
            };

            let mut guard = self
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard.as_mut().ok_or_else(|| {
                anyhow!("semantic search unavailable (no embedder or vector index)")
            })?;
            if let Some(existing) = state.progressive_context.as_ref() {
                return Ok(Some(Arc::clone(existing)));
            }
            if !Arc::ptr_eq(&state.context_token, &context_token) {
                continue;
            }
            state.progressive_context_unavailable = false;
            state.progressive_context = Some(Arc::clone(&context));
            return Ok(Some(context));
        }
    }

    fn build_progressive_context(
        &self,
        ann_path: Option<PathBuf>,
        embedder: Arc<dyn Embedder>,
        context_token: Arc<()>,
    ) -> Result<Option<Arc<ProgressiveTwoTierContext>>> {
        let Some(index_dir) = ann_path
            .as_ref()
            .and_then(|path| path.parent().map(Path::to_path_buf))
        else {
            return Ok(None);
        };

        let fast_path = {
            let explicit = index_dir.join("vector.fast.idx");
            if explicit.is_file() {
                explicit
            } else {
                let fallback = index_dir.join("vector.idx");
                if fallback.is_file() {
                    fallback
                } else {
                    return Ok(None);
                }
            }
        };
        let quality_path = index_dir.join("vector.quality.idx");
        if !quality_path.is_file() {
            return Ok(None);
        }

        let fast_index = FsVectorIndex::open(&fast_path)
            .map_err(|err| anyhow!("open fast-tier index failed: {err}"))?;
        let quality_index = FsVectorIndex::open(&quality_path)
            .map_err(|err| anyhow!("open quality-tier index failed: {err}"))?;
        let index = Arc::new(
            FsTwoTierIndex::open(&index_dir, frankensearch_two_tier_config())
                .map_err(|err| anyhow!("open progressive two-tier index failed: {err}"))?,
        );

        let fast_embedder = self.load_embedder_for_progressive_id(
            &embedder,
            fast_index.embedder_id(),
            fast_index.dimension(),
        )?;
        let fast_embedder: Arc<dyn frankensearch::Embedder> = Arc::new(FsSyncEmbedderAdapter(
            SharedCassSyncEmbedder::new(fast_embedder),
        ));
        let quality_embedder = Some(self.load_embedder_for_progressive_id(
            &embedder,
            quality_index.embedder_id(),
            quality_index.dimension(),
        )?);
        let quality_embedder = quality_embedder.map(|embedder| {
            Arc::new(FsSyncEmbedderAdapter(SharedCassSyncEmbedder::new(embedder)))
                as Arc<dyn frankensearch::Embedder>
        });

        Ok(Some(Arc::new(ProgressiveTwoTierContext {
            context_token,
            index,
            fast_embedder,
            quality_embedder,
        })))
    }

    fn load_embedder_for_progressive_id(
        &self,
        current_embedder: &Arc<dyn Embedder>,
        embedder_id: &str,
        dimension: usize,
    ) -> Result<Arc<dyn Embedder>> {
        if current_embedder.id() == embedder_id {
            return Ok(Arc::clone(current_embedder));
        }

        if let Some(dim) = embedder_id.strip_prefix("fnv1a-")
            && let Ok(parsed) = dim.parse::<usize>()
        {
            return Ok(Arc::new(crate::search::hash_embedder::HashEmbedder::new(
                parsed.max(dimension),
            )));
        }

        if let Some(embedder_name) =
            crate::search::fastembed_embedder::FastEmbedder::canonical_name(embedder_id)
        {
            let data_dir = self
                .sqlite_path
                .as_ref()
                .and_then(|path| path.parent())
                .ok_or_else(|| anyhow!("cannot resolve data dir for progressive embedder load"))?;
            let embedder = crate::search::fastembed_embedder::FastEmbedder::load_by_name(
                data_dir,
                embedder_name,
            )
            .with_context(|| format!("loading FastEmbed model for {embedder_name}"))?;
            if embedder.dimension() != dimension {
                bail!(
                    "progressive embedder dimension mismatch: {} index expects {}, model has {}",
                    embedder_id,
                    dimension,
                    embedder.dimension()
                );
            }
            return Ok(Arc::new(embedder));
        }

        bail!("unsupported progressive embedder id: {embedder_id}");
    }

    fn resolve_semantic_doc_ids_for_hits(
        &self,
        hits: &[SearchHit],
    ) -> Result<Vec<Option<ResolvedSemanticDocId>>> {
        if hits.is_empty() {
            return Ok(Vec::new());
        }

        let lookup_keys: Vec<Option<ProgressiveLookupKey>> = hits
            .iter()
            .map(|hit| {
                let idx = hit
                    .line_number
                    .and_then(|line| line.checked_sub(1))
                    .map(i64::try_from)
                    .transpose()
                    .ok()
                    .flatten()?;
                Some((
                    normalized_search_hit_source_id(hit),
                    hit.source_path.clone(),
                    hit.conversation_id,
                    hit.title.trim().to_string(),
                    idx,
                    hit.created_at,
                    hit.content_hash,
                ))
            })
            .collect();

        let mut seen_exact = HashSet::new();
        let mut exact_query_keys = Vec::new();
        let mut seen_fallback = HashSet::new();
        let mut fallback_query_keys = Vec::new();
        for (source_id, source_path, conversation_id, _title, idx, _created_at, _content_hash) in
            lookup_keys.iter().flatten()
        {
            if let Some(conversation_id) = conversation_id {
                let query_key: ProgressiveExactQueryKey = (*conversation_id, *idx);
                if seen_exact.insert(query_key) {
                    exact_query_keys.push(query_key);
                }
            } else {
                let query_key: ProgressiveFallbackQueryKey =
                    (source_id.clone(), source_path.clone(), *idx);
                if seen_fallback.insert(query_key.clone()) {
                    fallback_query_keys.push(query_key);
                }
            }
        }

        if exact_query_keys.is_empty() && fallback_query_keys.is_empty() {
            return Ok(vec![None; hits.len()]);
        }

        let sqlite_guard = self.sqlite_guard()?;
        let conn = sqlite_guard
            .as_ref()
            .ok_or_else(|| anyhow!("progressive search requires database connection"))?;

        let mut resolved_by_key = HashMap::new();
        let normalized_source_sql =
            normalized_search_source_id_sql_expr("c.source_id", "s.kind", "c.origin_host");

        const CHUNK_SIZE: usize = 300;
        for chunk in exact_query_keys.chunks(CHUNK_SIZE) {
            let mut sql = String::from("SELECT c.id, ");
            sql.push_str(&normalized_source_sql);
            sql.push_str(
                ", c.source_path, m.idx, m.id, c.agent_id, c.workspace_id, m.role, m.created_at, m.content, c.title
                 FROM messages m
                 JOIN conversations c ON m.conversation_id = c.id
                 LEFT JOIN sources s ON c.source_id = s.id
                 WHERE ",
            );
            let mut params = Vec::with_capacity(chunk.len().saturating_mul(2));
            for (idx, (conversation_id, line_idx)) in chunk.iter().enumerate() {
                if idx > 0 {
                    sql.push_str(" OR ");
                }
                sql.push_str("(c.id = ? AND m.idx = ?)");
                params.push(ParamValue::from(*conversation_id));
                params.push(ParamValue::from(*line_idx));
            }

            let chunk_rows: Vec<ResolvedSemanticLookupRow> =
                conn.query_map_collect(&sql, &params, |row: &frankensqlite::Row| {
                    let conversation_id: i64 = row.get_typed(0)?;
                    let source_id: String = row.get_typed(1)?;
                    let source_path: String = row.get_typed(2)?;
                    let idx: i64 = row.get_typed(3)?;
                    let message_id_raw: i64 = row.get_typed(4)?;
                    // agent_id is nullable for legacy V1 conversations; treat
                    // NULL the same as the negative-sentinel branch below (0).
                    let agent_id_raw: Option<i64> = row.get_typed(5)?;
                    let workspace_id_raw: Option<i64> = row.get_typed(6)?;
                    let role_raw: String = row.get_typed(7)?;
                    let created_at_ms: Option<i64> = row.get_typed(8)?;
                    let content: String = row.get_typed(9)?;
                    let title: Option<String> = row.get_typed(10)?;

                    let canonical = canonicalize_for_embedding(&content);
                    if canonical.is_empty() {
                        return Ok(None);
                    }

                    let message_id = u64::try_from(message_id_raw).map_err(|_| {
                        std::io::Error::other("message id out of range for progressive doc_id")
                    })?;
                    let agent_id = semantic_doc_component_id_from_db(agent_id_raw);
                    let workspace_id = semantic_doc_component_id_from_db(workspace_id_raw);
                    let role = role_code_from_str(&role_raw).unwrap_or(ROLE_USER);
                    let doc_id = SemanticDocId {
                        message_id,
                        chunk_idx: 0,
                        agent_id,
                        workspace_id,
                        source_id: crc32fast::hash(source_id.as_bytes()),
                        role,
                        created_at_ms: created_at_ms.unwrap_or(0),
                        content_hash: Some(content_hash(&canonical)),
                    }
                    .to_doc_id_string();
                    let line_number = usize::try_from(idx).ok().map(|line| line.saturating_add(1));
                    let lookup_key = (
                        source_id,
                        source_path.clone(),
                        Some(conversation_id),
                        title.unwrap_or_default().trim().to_string(),
                        idx,
                        created_at_ms,
                        stable_hit_hash(&content, &source_path, line_number, created_at_ms),
                    );

                    Ok(Some((
                        lookup_key,
                        ResolvedSemanticDocId { message_id, doc_id },
                    )))
                })?;

            for row in chunk_rows.into_iter().flatten() {
                resolved_by_key.insert(row.0, row.1);
            }
        }

        for chunk in fallback_query_keys.chunks(CHUNK_SIZE) {
            let mut sql = String::from("SELECT ");
            sql.push_str(&normalized_source_sql);
            sql.push_str(
                ", c.source_path, m.idx, m.id, c.agent_id, c.workspace_id, m.role, m.created_at, m.content, c.title
                 FROM messages m
                 JOIN conversations c ON m.conversation_id = c.id
                 LEFT JOIN sources s ON c.source_id = s.id
                 WHERE ",
            );
            let mut params = Vec::with_capacity(chunk.len().saturating_mul(3));
            for (idx, (source_id, source_path, line_idx)) in chunk.iter().enumerate() {
                if idx > 0 {
                    sql.push_str(" OR ");
                }
                sql.push_str(&format!(
                    "({normalized_source_sql} = ? AND c.source_path = ? AND m.idx = ?)"
                ));
                params.push(ParamValue::from(normalize_search_source_filter_value(
                    source_id,
                )));
                params.push(ParamValue::from(source_path.clone()));
                params.push(ParamValue::from(*line_idx));
            }

            let chunk_rows: Vec<ResolvedSemanticLookupRow> =
                conn.query_map_collect(&sql, &params, |row: &frankensqlite::Row| {
                    let source_id: String = row.get_typed(0)?;
                    let source_path: String = row.get_typed(1)?;
                    let idx: i64 = row.get_typed(2)?;
                    let message_id_raw: i64 = row.get_typed(3)?;
                    // agent_id is nullable for legacy V1 conversations; treat
                    // NULL the same as the negative-sentinel branch below (0).
                    let agent_id_raw: Option<i64> = row.get_typed(4)?;
                    let workspace_id_raw: Option<i64> = row.get_typed(5)?;
                    let role_raw: String = row.get_typed(6)?;
                    let created_at_ms: Option<i64> = row.get_typed(7)?;
                    let content: String = row.get_typed(8)?;
                    let title: Option<String> = row.get_typed(9)?;

                    let canonical = canonicalize_for_embedding(&content);
                    if canonical.is_empty() {
                        return Ok(None);
                    }

                    let message_id = u64::try_from(message_id_raw).map_err(|_| {
                        std::io::Error::other("message id out of range for progressive doc_id")
                    })?;
                    let agent_id = semantic_doc_component_id_from_db(agent_id_raw);
                    let workspace_id = semantic_doc_component_id_from_db(workspace_id_raw);
                    let role = role_code_from_str(&role_raw).unwrap_or(ROLE_USER);
                    let doc_id = SemanticDocId {
                        message_id,
                        chunk_idx: 0,
                        agent_id,
                        workspace_id,
                        source_id: crc32fast::hash(source_id.as_bytes()),
                        role,
                        created_at_ms: created_at_ms.unwrap_or(0),
                        content_hash: Some(content_hash(&canonical)),
                    }
                    .to_doc_id_string();
                    let line_number = usize::try_from(idx).ok().map(|line| line.saturating_add(1));
                    let lookup_key = (
                        source_id,
                        source_path.clone(),
                        None,
                        title.unwrap_or_default().trim().to_string(),
                        idx,
                        created_at_ms,
                        stable_hit_hash(&content, &source_path, line_number, created_at_ms),
                    );

                    Ok(Some((
                        lookup_key,
                        ResolvedSemanticDocId { message_id, doc_id },
                    )))
                })?;

            for row in chunk_rows.into_iter().flatten() {
                resolved_by_key.insert(row.0, row.1);
            }
        }

        Ok(lookup_keys
            .into_iter()
            .map(|key| key.and_then(|lookup| resolved_by_key.get(&lookup).cloned()))
            .collect())
    }

    fn load_message_text_by_id(&self, message_id: u64) -> Result<Option<String>> {
        let sqlite_guard = self.sqlite_guard()?;
        let conn = sqlite_guard
            .as_ref()
            .ok_or_else(|| anyhow!("progressive search requires database connection"))?;
        let rows: Vec<String> = conn.query_map_collect(
            "SELECT content FROM messages WHERE id = ?",
            &[ParamValue::from(i64::try_from(message_id)?)],
            |row: &frankensqlite::Row| row.get_typed(0),
        )?;
        Ok(rows.into_iter().next())
    }

    fn collapse_progressive_scored_results(
        &self,
        results: &[FsScoredResult],
        fetch_limit: usize,
    ) -> Vec<VectorSearchResult> {
        let fetch = fetch_limit.max(1);
        let mut best_by_message: HashMap<u64, VectorSearchResult> =
            HashMap::with_capacity(results.len());
        for hit in results {
            let Some(parsed) = parse_semantic_doc_id(&hit.doc_id) else {
                continue;
            };
            best_by_message
                .entry(parsed.message_id)
                .and_modify(|entry| {
                    if hit.score > entry.score {
                        entry.score = hit.score;
                        entry.chunk_idx = parsed.chunk_idx;
                    }
                })
                .or_insert(VectorSearchResult {
                    message_id: parsed.message_id,
                    chunk_idx: parsed.chunk_idx,
                    score: hit.score,
                });
        }
        let mut collapsed: Vec<VectorSearchResult> = best_by_message.into_values().collect();
        collapsed.sort_by(|a, b| {
            b.score
                .total_cmp(&a.score)
                .then_with(|| a.message_id.cmp(&b.message_id))
        });
        if collapsed.len() > fetch {
            collapsed.truncate(fetch);
        }
        collapsed
    }

    fn hydrate_semantic_hits_with_ids(
        &self,
        results: &[VectorSearchResult],
        field_mask: FieldMask,
    ) -> Result<Vec<(u64, SearchHit)>> {
        if results.is_empty() {
            return Ok(Vec::new());
        }
        let sqlite_guard = self.sqlite_guard()?;
        let conn = sqlite_guard
            .as_ref()
            .ok_or_else(|| anyhow!("semantic search requires database connection"))?;

        let placeholder_capacity = results.len().saturating_mul(2).saturating_sub(1);
        let mut placeholders = String::with_capacity(placeholder_capacity);
        let mut params: Vec<ParamValue> = Vec::with_capacity(results.len());
        for (idx, result) in results.iter().enumerate() {
            if idx > 0 {
                placeholders.push(',');
            }
            placeholders.push('?');
            params.push(ParamValue::from(i64::try_from(result.message_id)?));
        }

        let title_expr = if field_mask.wants_title() {
            "c.title"
        } else {
            "''"
        };
        let normalized_source_sql =
            normalized_search_source_id_sql_expr("c.source_id", "s.kind", "c.origin_host");
        // LEFT JOIN + COALESCE on agents so search hits for conversations
        // with NULL agent_id (legacy V1 schema) still surface instead of
        // being silently dropped from results.  Consistent with the fts/
        // lexical rebuild paths (8a0c547c, e1c08e7c).
        let sql = format!(
            "SELECT m.id, c.id, m.content, m.created_at, m.idx, m.role, {title_expr}, c.source_path, {normalized_source_sql}, c.origin_host, COALESCE(a.slug, 'unknown'), w.path, s.kind, c.started_at
             FROM messages m
             JOIN conversations c ON m.conversation_id = c.id
             LEFT JOIN agents a ON c.agent_id = a.id
             LEFT JOIN workspaces w ON c.workspace_id = w.id
             LEFT JOIN sources s ON c.source_id = s.id
             WHERE m.id IN ({placeholders})"
        );

        let rows: Vec<(u64, SearchHit)> =
            conn.query_map_collect(&sql, &params, |row: &frankensqlite::Row| {
                let message_id: i64 = row.get_typed(0)?;
                let conversation_id: i64 = row.get_typed(1)?;
                let full_content: String = row.get_typed(2)?;
                let msg_created_at: Option<i64> = row.get_typed(3)?;
                let idx: Option<i64> = row.get_typed(4)?;
                let title: Option<String> = if field_mask.wants_title() {
                    row.get_typed(6)?
                } else {
                    None
                };
                let source_path: String = row.get_typed(7)?;
                let raw_source_id: String = row.get_typed(8)?;
                let origin_host: Option<String> = row.get_typed(9)?;
                let agent: String = row.get_typed(10)?;
                let workspace: Option<String> = row.get_typed(11)?;
                let raw_origin_kind: Option<String> = row.get_typed(12)?;
                let started_at: Option<i64> = row.get_typed(13)?;

                let created_at = msg_created_at.or(started_at);
                let line_number = idx
                    .and_then(|i| usize::try_from(i).ok())
                    .map(|i| i.saturating_add(1));
                let snippet = if field_mask.wants_snippet() {
                    snippet_from_content(&full_content)
                } else {
                    String::new()
                };
                let content = if field_mask.needs_content() {
                    full_content.clone()
                } else {
                    String::new()
                };
                let content_hash =
                    stable_hit_hash(&full_content, &source_path, line_number, created_at);
                let source_id = normalized_search_hit_source_id_parts(
                    raw_source_id.as_str(),
                    raw_origin_kind.as_deref().unwrap_or_default(),
                    origin_host.as_deref(),
                );
                let origin_kind =
                    normalized_search_hit_origin_kind(&source_id, raw_origin_kind.as_deref());

                let hit = SearchHit {
                    title: if field_mask.wants_title() {
                        title.unwrap_or_default()
                    } else {
                        String::new()
                    },
                    snippet,
                    content,
                    content_hash,
                    conversation_id: Some(conversation_id),
                    score: 0.0,
                    source_path,
                    agent,
                    workspace: workspace.unwrap_or_default(),
                    workspace_original: None,
                    created_at,
                    line_number,
                    match_type: MatchType::Exact,
                    source_id,
                    origin_kind,
                    origin_host,
                };

                Ok((semantic_message_id_from_db(message_id)?, hit))
            })?;

        let mut hits_by_id = HashMap::new();
        for (id, hit) in rows {
            hits_by_id.insert(id, hit);
        }

        let mut ordered = Vec::new();
        for result in results {
            if let Some(mut hit) = hits_by_id.remove(&result.message_id) {
                hit.score = result.score;
                ordered.push((result.message_id, hit));
            }
        }

        Ok(ordered)
    }

    fn overlay_progressive_lexical_hit(
        &self,
        hit: &mut SearchHit,
        lexical: &ProgressiveLexicalHit,
        field_mask: FieldMask,
    ) {
        if field_mask.wants_title() && !lexical.title.is_empty() {
            hit.title = lexical.title.clone();
        }
        if field_mask.wants_snippet() && !lexical.snippet.is_empty() {
            hit.snippet = lexical.snippet.clone();
        }
        if field_mask.needs_content() && !lexical.content.is_empty() {
            hit.content = lexical.content.clone();
        }
        hit.match_type = lexical.match_type;
        hit.line_number = lexical.line_number.or(hit.line_number);
    }

    fn progressive_phase_to_result(
        &self,
        results: &[FsScoredResult],
        ctx: ProgressivePhaseContext<'_>,
    ) -> Result<SearchResult> {
        let collapsed = self.collapse_progressive_scored_results(results, ctx.fetch_limit);
        let missing: Vec<VectorSearchResult> = collapsed
            .iter()
            .filter(|result| {
                ctx.lexical_cache
                    .and_then(|cache| cache.hits_by_message.get(&result.message_id))
                    .is_none()
            })
            .map(|result| VectorSearchResult {
                message_id: result.message_id,
                chunk_idx: result.chunk_idx,
                score: result.score,
            })
            .collect();
        let mut hydrated_by_id: HashMap<u64, SearchHit> = self
            .hydrate_semantic_hits_with_ids(&missing, ctx.field_mask)?
            .into_iter()
            .collect();

        let mut hydrated: Vec<(u64, SearchHit)> = Vec::with_capacity(collapsed.len());
        for result in &collapsed {
            if let Some(cache) = ctx.lexical_cache
                && let Some(lexical) = cache.hits_by_message.get(&result.message_id)
            {
                hydrated.push((result.message_id, lexical.to_search_hit(result.score)));
                continue;
            }
            if let Some(mut hit) = hydrated_by_id.remove(&result.message_id) {
                if let Some(cache) = ctx.lexical_cache
                    && let Some(lexical) = cache.hits_by_message.get(&result.message_id)
                {
                    self.overlay_progressive_lexical_hit(&mut hit, lexical, ctx.field_mask);
                }
                hydrated.push((result.message_id, hit));
            }
        }

        let mut hits: Vec<SearchHit> = hydrated.into_iter().map(|(_, hit)| hit).collect();
        (_, hits) = self.postprocess_hits_page(hits, ctx.query, ctx.filters, ctx.limit, 0);

        let (wildcard_fallback, suggestions) = ctx
            .lexical_cache
            .map(|cache| {
                let suggestions = if hits.is_empty() {
                    cache.suggestions.clone()
                } else {
                    Vec::new()
                };
                (cache.wildcard_fallback, suggestions)
            })
            .unwrap_or((false, Vec::new()));

        Ok(SearchResult {
            hits,
            wildcard_fallback,
            cache_stats: self.cache_stats(),
            suggestions,
            ann_stats: None,
            total_count: None,
        })
    }

    pub(crate) async fn search_progressive_with_callback(
        self: &Arc<Self>,
        request: ProgressiveSearchRequest<'_>,
        mut on_event: impl FnMut(ProgressiveSearchEvent) + Send,
    ) -> Result<()> {
        let ProgressiveSearchRequest {
            cx,
            query,
            filters,
            limit,
            sparse_threshold,
            field_mask,
            mode,
        } = request;
        let field_mask = effective_field_mask(field_mask);
        let limit = limit.max(1);
        let fetch_limit = progressive_phase_fetch_limit(limit);

        match mode {
            SearchMode::Lexical => {
                let started = Instant::now();
                let result = self.search_with_fallback(
                    query,
                    filters,
                    limit,
                    0,
                    sparse_threshold,
                    field_mask,
                )?;
                on_event(ProgressiveSearchEvent::Phase {
                    kind: ProgressivePhaseKind::Initial,
                    elapsed_ms: started.elapsed().as_millis(),
                    result,
                });
                return Ok(());
            }
            SearchMode::Semantic | SearchMode::Hybrid => {}
        }

        let progressive_context = {
            self.progressive_context()?
                .ok_or_else(|| anyhow!("progressive two-tier context unavailable"))?
        };
        let progressive_context_token = Arc::clone(&progressive_context.context_token);

        let lexical_cache: Arc<Mutex<ProgressiveLexicalSnapshot>> =
            Arc::new(Mutex::new(Arc::new(ProgressiveLexicalCache::default())));
        let text_cache: Arc<Mutex<HashMap<u64, String>>> = Arc::new(Mutex::new(HashMap::new()));
        let text_client = Arc::clone(self);
        let text_cache_for_lookup = Arc::clone(&text_cache);
        let text_fn = move |doc_id: &str| -> Option<String> {
            let parsed = parse_semantic_doc_id(doc_id)?;
            if let Ok(cache) = text_cache_for_lookup.lock()
                && let Some(text) = cache.get(&parsed.message_id)
            {
                return Some(text.clone());
            }
            let loaded = text_client
                .load_message_text_by_id(parsed.message_id)
                .ok()
                .flatten()?;
            if let Ok(mut cache) = text_cache_for_lookup.lock() {
                cache.insert(parsed.message_id, loaded.clone());
            }
            Some(loaded)
        };

        let mut searcher = FsTwoTierSearcher::new(
            Arc::clone(&progressive_context.index),
            Arc::clone(&progressive_context.fast_embedder),
            frankensearch_two_tier_config(),
        );

        if let Some(quality_embedder) = progressive_context.quality_embedder.as_ref() {
            searcher = searcher.with_quality_embedder(Arc::clone(quality_embedder));
        }

        if matches!(mode, SearchMode::Hybrid) {
            let lexical = Arc::new(CassProgressiveLexicalAdapter::new(
                Arc::clone(self),
                filters.clone(),
                field_mask,
                sparse_threshold,
                Arc::clone(&lexical_cache),
            ));
            searcher = searcher.with_lexical(lexical);
        }

        let phase_client = Arc::clone(self);
        let phase_filters = filters.clone();
        let phase_cache = Arc::clone(&lexical_cache);
        let mut phase_error: Option<anyhow::Error> = None;

        let search_result = searcher
            .search(cx, query, fetch_limit, text_fn, |phase| {
                if phase_error.is_some() {
                    return;
                }
                match phase_client.semantic_context_matches(&progressive_context_token) {
                    Ok(true) => {}
                    Ok(false) => {
                        phase_error = Some(anyhow!(
                            "progressive search aborted: semantic context changed"
                        ));
                        cx.set_cancel_requested(true);
                        return;
                    }
                    Err(err) => {
                        phase_error = Some(err);
                        cx.set_cancel_requested(true);
                        return;
                    }
                }
                let lexical_snapshot = phase_cache.lock().ok().map(|guard| Arc::clone(&guard));
                let event_result = match phase {
                    FsSearchPhase::Initial {
                        results, latency, ..
                    } => phase_client
                        .progressive_phase_to_result(
                            &results,
                            ProgressivePhaseContext {
                                query,
                                filters: &phase_filters,
                                field_mask,
                                lexical_cache: lexical_snapshot.as_deref(),
                                limit,
                                fetch_limit,
                            },
                        )
                        .map(|result| ProgressiveSearchEvent::Phase {
                            kind: ProgressivePhaseKind::Initial,
                            elapsed_ms: latency.as_millis(),
                            result,
                        }),
                    FsSearchPhase::Refined {
                        results, latency, ..
                    } => phase_client
                        .progressive_phase_to_result(
                            &results,
                            ProgressivePhaseContext {
                                query,
                                filters: &phase_filters,
                                field_mask,
                                lexical_cache: lexical_snapshot.as_deref(),
                                limit,
                                fetch_limit,
                            },
                        )
                        .map(|result| ProgressiveSearchEvent::Phase {
                            kind: ProgressivePhaseKind::Refined,
                            elapsed_ms: latency.as_millis(),
                            result,
                        }),
                    // frankensearch may emit a final reranked phase after the
                    // quality-refined pass. cass's progressive consumers only
                    // distinguish fast initial results from a better upgraded
                    // replacement set, so reranked results flow through the
                    // existing refined/upgrade path.
                    FsSearchPhase::Reranked {
                        results, latency, ..
                    } => phase_client
                        .progressive_phase_to_result(
                            &results,
                            ProgressivePhaseContext {
                                query,
                                filters: &phase_filters,
                                field_mask,
                                lexical_cache: lexical_snapshot.as_deref(),
                                limit,
                                fetch_limit,
                            },
                        )
                        .map(|result| ProgressiveSearchEvent::Phase {
                            kind: ProgressivePhaseKind::Refined,
                            elapsed_ms: latency.as_millis(),
                            result,
                        }),
                    FsSearchPhase::RefinementFailed { error, latency, .. } => {
                        Ok(ProgressiveSearchEvent::RefinementFailed {
                            latency_ms: latency.as_millis(),
                            error: error.to_string(),
                        })
                    }
                };

                match event_result {
                    Ok(event) => on_event(event),
                    Err(err) => {
                        phase_error = Some(err);
                        cx.set_cancel_requested(true);
                    }
                }
            })
            .await;

        if let Some(err) = phase_error {
            return Err(err);
        }

        search_result
            .map(|_| ())
            .map_err(|err| anyhow!("progressive search failed: {err}"))
    }

    /// Semantic search result containing hits and optional ANN statistics.
    pub fn search_semantic(
        &self,
        query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        field_mask: FieldMask,
        approximate: bool,
    ) -> Result<(
        Vec<SearchHit>,
        Option<crate::search::ann_index::AnnSearchStats>,
    )> {
        self.search_semantic_with_tier(
            query,
            filters,
            limit,
            offset,
            field_mask,
            approximate,
            SemanticTierMode::Single,
        )
    }

    /// Semantic search with optional progressive two-tier execution strategy.
    #[allow(clippy::too_many_arguments)]
    pub fn search_semantic_with_tier(
        &self,
        query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        field_mask: FieldMask,
        approximate: bool,
        tier_mode: SemanticTierMode,
    ) -> Result<(
        Vec<SearchHit>,
        Option<crate::search::ann_index::AnnSearchStats>,
    )> {
        let field_mask = effective_field_mask(field_mask);
        let canonical = canonicalize_for_embedding(query);
        if canonical.trim().is_empty() {
            return Ok((Vec::new(), None));
        }
        let limit = if limit == 0 {
            self.total_docs().min(no_limit_result_cap()).max(1)
        } else {
            limit
        };
        let target_hits = limit.saturating_add(offset);
        if target_hits == 0 {
            return Ok((Vec::new(), None));
        }
        let initial_fetch_limit = target_hits;
        let fallback_fetch_limit = target_hits.saturating_mul(3);
        loop {
            let (embedding, candidate_context, in_memory_two_tier_index, ann_index, context_token) = loop {
                let embedding = self.semantic_query_embedding(&canonical)?;
                let (candidate_context, context_token) = {
                    let guard = self
                        .semantic
                        .lock()
                        .map_err(|_| anyhow!("semantic lock poisoned"))?;
                    let state = guard.as_ref().ok_or_else(|| {
                        anyhow!("semantic search unavailable (no embedder or vector index)")
                    })?;
                    (
                        SemanticCandidateContext {
                            fs_semantic_index: Arc::clone(&state.fs_semantic_index),
                            fs_semantic_indexes: Arc::clone(&state.fs_semantic_indexes),
                            filter_maps: state.filter_maps.clone(),
                            roles: state.roles.clone(),
                        },
                        Arc::clone(&state.context_token),
                    )
                };
                if !Arc::ptr_eq(&embedding.context_token, &context_token) {
                    continue;
                }
                let in_memory_two_tier_index = if tier_mode.wants_two_tier() && !approximate {
                    self.in_memory_two_tier_index(tier_mode)?
                } else {
                    None
                };
                let ann_index = if approximate {
                    Some(self.ann_index()?)
                } else {
                    None
                };

                let guard = self
                    .semantic
                    .lock()
                    .map_err(|_| anyhow!("semantic lock poisoned"))?;
                let state = guard.as_ref().ok_or_else(|| {
                    anyhow!("semantic search unavailable (no embedder or vector index)")
                })?;
                if !Arc::ptr_eq(&state.context_token, &context_token) {
                    continue;
                }
                break (
                    embedding.vector,
                    candidate_context,
                    in_memory_two_tier_index,
                    ann_index,
                    context_token,
                );
            };

            let finalize_hits =
                |results: &[VectorSearchResult]| -> Result<(usize, Vec<SearchHit>)> {
                    let hits = self.hydrate_semantic_hits(results, field_mask)?;
                    Ok(self.postprocess_hits_page(hits, query, &filters, limit, offset))
                };

            let (results, retry_state, mut ann_stats) = self.search_semantic_candidates(
                &candidate_context,
                &embedding,
                &filters,
                SemanticCandidateSearchRequest {
                    fetch_limit: initial_fetch_limit,
                    approximate,
                    tier_mode,
                    in_memory_two_tier_index: in_memory_two_tier_index.as_ref(),
                    ann_index: ann_index.as_ref(),
                },
            )?;
            if !self.semantic_context_matches(&context_token)? {
                tracing::debug!("semantic context changed during candidate search; retrying");
                continue;
            }
            let (mut available_hits, mut paged_hits) = finalize_hits(&results)?;

            let needs_retry = initial_fetch_limit < fallback_fetch_limit
                && ((available_hits < target_hits && retry_state.has_more_candidates)
                    || retry_state.exact_window_may_omit_competitor);

            if needs_retry {
                tracing::debug!(
                    query = canonical,
                    target_hits,
                    available_hits,
                    initial_fetch_limit,
                    fallback_fetch_limit,
                    "retrying semantic fetch due to candidate-window shortfall"
                );
                let (retry_results, _, retry_ann_stats) = self.search_semantic_candidates(
                    &candidate_context,
                    &embedding,
                    &filters,
                    SemanticCandidateSearchRequest {
                        fetch_limit: fallback_fetch_limit,
                        approximate,
                        tier_mode,
                        in_memory_two_tier_index: in_memory_two_tier_index.as_ref(),
                        ann_index: ann_index.as_ref(),
                    },
                )?;
                if !self.semantic_context_matches(&context_token)? {
                    tracing::debug!("semantic context changed during retry fetch; retrying");
                    continue;
                }
                (available_hits, paged_hits) = finalize_hits(&retry_results)?;
                ann_stats = retry_ann_stats;
            }

            tracing::trace!(
                query = canonical,
                target_hits,
                available_hits,
                returned = paged_hits.len(),
                "semantic fetch complete"
            );

            return Ok((paged_hits, ann_stats));
        }
    }

    fn hydrate_semantic_hits(
        &self,
        results: &[VectorSearchResult],
        field_mask: FieldMask,
    ) -> Result<Vec<SearchHit>> {
        self.hydrate_semantic_hits_with_ids(results, field_mask)
            .map(|rows| rows.into_iter().map(|(_, hit)| hit).collect())
    }

    fn postprocess_hits_page(
        &self,
        hits: Vec<SearchHit>,
        query: &str,
        filters: &SearchFilters,
        limit: usize,
        offset: usize,
    ) -> (usize, Vec<SearchHit>) {
        let mut hits = deduplicate_hits_with_query(hits, query);
        if !filters.session_paths.is_empty() {
            hits.retain(|hit| filters.session_paths.contains(&hit.source_path));
        }
        let available_hits = hits.len();
        let paged_hits = hits.into_iter().skip(offset).take(limit).collect();
        (available_hits, paged_hits)
    }

    /// Search with automatic wildcard fallback for sparse results.
    /// If the initial search returns fewer than `sparse_threshold` results and the query
    /// doesn't already contain wildcards, automatically retry with substring wildcards (*term*).
    pub fn search_with_fallback(
        &self,
        query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        sparse_threshold: usize,
        field_mask: FieldMask,
    ) -> Result<SearchResult> {
        // First, try the normal search
        let hits = self.search(query, filters.clone(), limit, offset, field_mask)?;
        let baseline_stats = self.cache_stats();
        // Capture the true total from Tantivy's Count collector (set during search_tantivy).
        let tantivy_total = self
            .last_tantivy_total_count
            .lock()
            .ok()
            .and_then(|guard| *guard);

        // Check if we should try wildcard fallback
        let query_has_wildcards = query.contains('*');
        let has_boolean_or_phrase = fs_cass_has_boolean_operators(query);
        let is_sparse = should_try_wildcard_fallback(hits.len(), limit, offset, sparse_threshold);

        if !is_sparse || query_has_wildcards || has_boolean_or_phrase || query.trim().is_empty() {
            // Either we have enough results, query already has wildcards,
            // query uses boolean/phrases, or query is empty.
            // Generate suggestions only if truly zero hits
            let suggestions = if hits.is_empty() && !query.trim().is_empty() {
                self.generate_suggestions(query, &filters)
            } else {
                Vec::new()
            };
            return Ok(SearchResult {
                hits,
                wildcard_fallback: false,
                cache_stats: baseline_stats,
                suggestions,
                ann_stats: None,
                total_count: tantivy_total,
            });
        }

        if should_skip_automatic_wildcard_fallback_for_long_zero_hit_query(query, hits.len()) {
            let suggestions = if hits.is_empty() {
                self.generate_suggestions(query, &filters)
            } else {
                Vec::new()
            };
            return Ok(SearchResult {
                hits,
                wildcard_fallback: false,
                cache_stats: baseline_stats,
                suggestions,
                ann_stats: None,
                total_count: tantivy_total,
            });
        }

        // Try wildcard fallback: wrap each term in *term*
        let wildcard_query = query
            .split_whitespace()
            .map(|term| format!("*{}*", term.trim_matches('*')))
            .collect::<Vec<_>>()
            .join(" ");

        tracing::info!(
            original_query = query,
            wildcard_query = wildcard_query,
            original_count = hits.len(),
            "wildcard_fallback"
        );

        let mut fallback_hits =
            self.search(&wildcard_query, filters.clone(), limit, offset, field_mask)?;
        let fallback_stats = self.cache_stats();
        // Re-capture total_count after wildcard search (may have changed)
        let fallback_tantivy_total = self
            .last_tantivy_total_count
            .lock()
            .ok()
            .and_then(|guard| *guard);

        // Use fallback results if they're better
        if fallback_hits.len() > hits.len() {
            // Mark all hits as ImplicitWildcard since we auto-added wildcards
            for hit in &mut fallback_hits {
                hit.match_type = MatchType::ImplicitWildcard;
            }
            // Generate suggestions if still zero hits after fallback
            let suggestions = if fallback_hits.is_empty() {
                self.generate_suggestions(query, &filters)
            } else {
                Vec::new()
            };
            Ok(SearchResult {
                hits: fallback_hits,
                wildcard_fallback: true,
                cache_stats: fallback_stats,
                suggestions,
                ann_stats: None,
                total_count: fallback_tantivy_total,
            })
        } else {
            // Keep original results even if sparse
            // Generate suggestions if zero hits
            let suggestions = if hits.is_empty() {
                self.generate_suggestions(query, &filters)
            } else {
                Vec::new()
            };
            Ok(SearchResult {
                hits,
                wildcard_fallback: false,
                cache_stats: baseline_stats,
                suggestions,
                ann_stats: None,
                total_count: tantivy_total,
            })
        }
    }

    /// Hybrid search that fuses lexical + semantic results with RRF.
    #[allow(clippy::too_many_arguments)]
    pub fn search_hybrid(
        &self,
        lexical_query: &str,
        semantic_query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        sparse_threshold: usize,
        field_mask: FieldMask,
        approximate: bool,
    ) -> Result<SearchResult> {
        self.search_hybrid_with_tier(
            lexical_query,
            semantic_query,
            filters,
            limit,
            offset,
            sparse_threshold,
            field_mask,
            approximate,
            SemanticTierMode::Single,
        )
    }

    /// Hybrid search that fuses lexical + semantic results with optional
    /// progressive two-tier semantic execution.
    #[allow(clippy::too_many_arguments)]
    pub fn search_hybrid_with_tier(
        &self,
        lexical_query: &str,
        semantic_query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        sparse_threshold: usize,
        field_mask: FieldMask,
        approximate: bool,
        semantic_tier_mode: SemanticTierMode,
    ) -> Result<SearchResult> {
        let requested_limit = limit;
        let total_docs = self.total_docs().max(1);
        let limit = if requested_limit == 0 {
            total_docs.min(no_limit_result_cap()).max(1)
        } else {
            requested_limit
        };
        let fetch = limit.saturating_add(offset);
        if fetch == 0 {
            return Ok(SearchResult {
                hits: Vec::new(),
                wildcard_fallback: false,
                cache_stats: self.cache_stats(),
                suggestions: Vec::new(),
                ann_stats: None,
                total_count: None,
            });
        }

        if semantic_query.trim().is_empty() {
            return self.search_with_fallback(
                lexical_query,
                filters,
                limit,
                offset,
                sparse_threshold,
                field_mask,
            );
        }

        let budget =
            hybrid_candidate_budget(semantic_query, requested_limit, limit, offset, total_docs);
        let lexical = self.search_with_fallback(
            lexical_query,
            filters.clone(),
            budget.lexical_candidates,
            0,
            sparse_threshold,
            field_mask,
        )?;
        let (semantic_hits, semantic_ann_stats) = self.search_semantic_with_tier(
            semantic_query,
            filters,
            budget.semantic_candidates,
            0,
            field_mask,
            approximate,
            semantic_tier_mode,
        )?;
        let fused = rrf_fuse_hits(&lexical.hits, &semantic_hits, semantic_query, limit, offset);
        let suggestions = if fused.is_empty() {
            lexical.suggestions.clone()
        } else {
            Vec::new()
        };
        Ok(SearchResult {
            hits: fused,
            wildcard_fallback: lexical.wildcard_fallback,
            cache_stats: lexical.cache_stats,
            suggestions,
            ann_stats: semantic_ann_stats,
            total_count: None,
        })
    }

    /// Generate "did-you-mean" suggestions for zero-hit queries.
    fn generate_suggestions(&self, query: &str, filters: &SearchFilters) -> Vec<QuerySuggestion> {
        let mut suggestions = Vec::new();
        let query_lower = query.to_lowercase();

        // 1. Suggest wildcard search if query doesn't have wildcards
        if !query.contains('*') && query.len() >= 2 {
            suggestions.push(QuerySuggestion::wildcard(query).with_shortcut(1));
        }

        // 2. Suggest removing agent filter if one is set
        if !filters.agents.is_empty() {
            let agents: Vec<&str> = filters
                .agents
                .iter()
                .map(std::string::String::as_str)
                .collect();
            let agent_str = agents.join(", ");
            suggestions
                .push(QuerySuggestion::remove_agent_filter(&agent_str, filters).with_shortcut(2));
        }

        // 3. Suggest common agent names if query looks like a typo of one
        let known_agents = [
            "codex",
            "claude",
            "claude_code",
            "cline",
            "gemini",
            "amp",
            "opencode",
        ];
        for agent in &known_agents {
            if levenshtein_distance(&query_lower, agent) <= 2 && query_lower != *agent {
                suggestions.push(
                    QuerySuggestion::spelling(query, agent)
                        .with_shortcut(suggestions.len().min(2) as u8 + 1),
                );
                break; // Only suggest one spelling fix
            }
        }

        // 4. Suggest alternative agents if SQLite is already open and no agent
        // filter is set. Avoid lazy-opening storage solely for no-hit advice:
        // large read-only frankensqlite opens can dominate fast lexical misses.
        if filters.agents.is_empty()
            && let Ok(sqlite_guard) = self.sqlite.lock()
            && let Some(conn) = sqlite_guard.as_ref()
            && let Ok(rows) = conn.query_map_collect(
                "SELECT a.slug
                 FROM conversations c
                 JOIN agents a ON c.agent_id = a.id
                 GROUP BY a.slug
                 ORDER BY MAX(c.id) DESC
                 LIMIT 3",
                &[],
                |row: &frankensqlite::Row| row.get_typed::<String>(0),
            )
        {
            for row in rows {
                if suggestions.len() < 3 {
                    suggestions.push(
                        QuerySuggestion::try_agent(&row)
                            .with_shortcut(suggestions.len().min(2) as u8 + 1),
                    );
                }
            }
        }

        // Ensure we have at most 3 suggestions with shortcuts 1, 2, 3
        suggestions.truncate(3);
        for (i, sugg) in suggestions.iter_mut().enumerate() {
            sugg.shortcut = Some((i + 1) as u8);
        }

        suggestions
    }

    fn searcher_for_thread(&self, reader: &IndexReader) -> Searcher {
        let epoch = self.reload_epoch.load(Ordering::Relaxed);
        let reader_key = reader as *const IndexReader as usize;
        THREAD_SEARCHER.with(|slot| {
            let mut slot = slot.borrow_mut();
            if let Some(entry) = slot.as_ref()
                && entry.epoch == epoch
                && entry.reader_key == reader_key
            {
                return entry.searcher.clone();
            }
            let searcher = reader.searcher();
            *slot = Some(SearcherCacheEntry {
                epoch,
                reader_key,
                searcher: searcher.clone(),
            });
            searcher
        })
    }

    fn federated_readers(&self) -> Option<Arc<Vec<FederatedIndexReader>>> {
        FEDERATED_SEARCH_READERS
            .read()
            .get(&self.cache_namespace)
            .cloned()
    }

    fn maybe_reload_federated_readers(
        &self,
        readers: &[FederatedIndexReader],
    ) -> Result<Option<u64>> {
        if !self.reload_on_search || readers.is_empty() {
            return Ok(None);
        }
        const MIN_RELOAD_INTERVAL: Duration = Duration::from_millis(300);
        let now = Instant::now();
        let mut guard = self.last_reload.lock().unwrap_or_else(|e| e.into_inner());
        if guard
            .map(|t| now.duration_since(t) < MIN_RELOAD_INTERVAL)
            .unwrap_or(false)
        {
            let signature = self.federated_generation_signature(readers);
            return Ok(Some(signature));
        }

        let reload_started = Instant::now();
        for shard in readers {
            shard.reader.reload()?;
        }
        let elapsed = reload_started.elapsed();
        *guard = Some(now);
        let epoch = self.reload_epoch.fetch_add(1, Ordering::SeqCst) + 1;
        self.metrics.record_reload(elapsed);
        tracing::debug!(
            duration_ms = elapsed.as_millis() as u64,
            reload_epoch = epoch,
            shards = readers.len(),
            "tantivy_reader_reload_federated"
        );
        Ok(Some(self.federated_generation_signature(readers)))
    }

    fn federated_generation_signature(&self, readers: &[FederatedIndexReader]) -> u64 {
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        readers.len().hash(&mut hasher);
        for shard in readers {
            self.searcher_for_thread(&shard.reader)
                .generation()
                .generation_id()
                .hash(&mut hasher);
        }
        hasher.finish()
    }

    fn track_generation(&self, generation: u64) {
        let mut guard = self
            .last_generation
            .lock()
            .unwrap_or_else(|e| e.into_inner());
        if let Some(prev) = *guard
            && prev != generation
            && let Ok(mut cache) = self.prefix_cache.lock()
        {
            cache.clear();
        }
        *guard = Some(generation);
    }

    fn hydrate_tantivy_hit_contents(
        &self,
        exact_keys: &[TantivyContentExactKey],
        fallback_keys: &[TantivyContentFallbackKey],
    ) -> Result<TantivyHydratedContentMaps> {
        if exact_keys.is_empty() && fallback_keys.is_empty() {
            return Ok((HashMap::new(), HashMap::new()));
        }

        let sqlite_guard = match self.sqlite_guard() {
            Ok(guard) => guard,
            Err(_) => return Ok((HashMap::new(), HashMap::new())),
        };
        let Some(conn) = sqlite_guard.as_ref() else {
            return Ok((HashMap::new(), HashMap::new()));
        };

        let mut hydrated_exact = HashMap::new();
        let mut hydrated_fallback = HashMap::new();
        const CHUNK_SIZE: usize = 300;

        if !exact_keys.is_empty() {
            let mut unique_exact_keys = Vec::with_capacity(exact_keys.len());
            let mut seen = HashSet::with_capacity(exact_keys.len());
            for key in exact_keys {
                if seen.insert(*key) {
                    unique_exact_keys.push(*key);
                }
            }

            hydrated_exact.extend(hydrate_message_content_by_conversation(
                conn,
                &unique_exact_keys,
            )?);
        }

        if !fallback_keys.is_empty() {
            let mut unique_fallback_keys = Vec::with_capacity(fallback_keys.len());
            let mut seen = HashSet::with_capacity(fallback_keys.len());
            for key in fallback_keys {
                if seen.insert(key.clone()) {
                    unique_fallback_keys.push(key.clone());
                }
            }

            let mut unique_source_paths = Vec::with_capacity(unique_fallback_keys.len());
            let mut seen_source_paths = HashSet::with_capacity(unique_fallback_keys.len());
            for (_, source_path, _) in &unique_fallback_keys {
                if seen_source_paths.insert(source_path.clone()) {
                    unique_source_paths.push(source_path.clone());
                }
            }

            let mut conversations_by_key: HashMap<(String, String), Vec<i64>> = HashMap::new();
            for chunk in unique_source_paths.chunks(CHUNK_SIZE) {
                let placeholders = sql_placeholders(chunk.len());
                let sql = format!(
                    "SELECT c.id,
                            c.source_path,
                            COALESCE(c.source_id, ''),
                            COALESCE(c.origin_host, ''),
                            COALESCE(s.kind, '')
                     FROM conversations c
                     LEFT JOIN sources s ON c.source_id = s.id
                     WHERE c.source_path IN ({placeholders})
                     ORDER BY c.id"
                );
                let params = chunk
                    .iter()
                    .map(|source_path| ParamValue::from(source_path.clone()))
                    .collect::<Vec<_>>();
                let rows: Vec<(i64, String, String, String, String)> =
                    franken_query_map_collect_retry(conn, &sql, &params, |row| {
                        Ok((
                            row.get_typed(0)?,
                            row.get_typed(1)?,
                            row.get_typed(2)?,
                            row.get_typed(3)?,
                            row.get_typed(4)?,
                        ))
                    })?;

                for (conversation_id, source_path, raw_source_id, origin_host, origin_kind) in rows
                {
                    let normalized_source_id = normalized_search_hit_source_id_parts(
                        &raw_source_id,
                        &origin_kind,
                        (!origin_host.trim().is_empty()).then_some(origin_host.as_str()),
                    );
                    conversations_by_key
                        .entry((normalized_source_id, source_path))
                        .or_default()
                        .push(conversation_id);
                }
            }

            let mut message_requests = Vec::new();
            let mut fallback_keys_by_exact: HashMap<
                TantivyContentExactKey,
                Vec<TantivyContentFallbackKey>,
            > = HashMap::new();
            let mut seen_message_requests = HashSet::new();
            for (source_id, source_path, line_idx) in &unique_fallback_keys {
                let key = (source_id.clone(), source_path.clone());
                let Some(conversation_ids) = conversations_by_key.get(&key) else {
                    continue;
                };
                for &conversation_id in conversation_ids {
                    let exact_key = (conversation_id, *line_idx);
                    if seen_message_requests.insert(exact_key) {
                        message_requests.push(exact_key);
                    }
                    fallback_keys_by_exact.entry(exact_key).or_default().push((
                        source_id.clone(),
                        source_path.clone(),
                        *line_idx,
                    ));
                }
            }

            for ((conversation_id, line_idx), content) in
                hydrate_message_content_by_conversation(conn, &message_requests)?
            {
                if let Some(fallback_keys) =
                    fallback_keys_by_exact.get(&(conversation_id, line_idx))
                {
                    for fallback_key in fallback_keys {
                        hydrated_fallback.insert(fallback_key.clone(), content.clone());
                    }
                }
            }
        }

        Ok((hydrated_exact, hydrated_fallback))
    }

    #[allow(clippy::too_many_arguments)]
    fn search_tantivy(
        &self,
        reader: &IndexReader,
        fields: &FsCassFields,
        raw_query: &str,
        sanitized_query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        field_mask: FieldMask,
    ) -> Result<(Vec<SearchHit>, usize)> {
        struct PendingTantivyHit {
            score: f32,
            doc: TantivyDocument,
            title: String,
            stored_content: String,
            stored_preview: String,
            agent: String,
            source_path: String,
            workspace: String,
            workspace_original: Option<String>,
            created_at: Option<i64>,
            line_number: Option<usize>,
            stored_preview_snippet: Option<String>,
            source_id: String,
            conversation_id: Option<i64>,
            raw_origin_kind: Option<String>,
            origin_host: Option<String>,
        }

        self.maybe_reload_reader(reader)?;
        let searcher = self.searcher_for_thread(reader);
        self.track_generation(searcher.generation().generation_id());

        let wants_snippet = field_mask.wants_snippet();
        let needs_content = field_mask.needs_content() || wants_snippet;

        // Delegate cass-compatible query parsing + Tantivy clause construction to frankensearch.
        // cass retains ownership of paging/fallback orchestration and stored-field hydration.
        let fs_filters = FsCassQueryFilters {
            agents: filters.agents.into_iter().collect(),
            workspaces: filters.workspaces.into_iter().collect(),
            created_from: filters.created_from,
            created_to: filters.created_to,
            source_filter: match filters.source_filter {
                SourceFilter::All => FsCassSourceFilter::All,
                SourceFilter::Local => FsCassSourceFilter::Local,
                SourceFilter::Remote => FsCassSourceFilter::Remote,
                SourceFilter::SourceId(id) => {
                    FsCassSourceFilter::SourceId(normalize_search_source_filter_value(&id))
                }
            },
        };

        // NOTE: session_paths filtering is applied post-search since source_path
        // is STORED but not indexed. See apply_session_paths_filter().
        let q: Box<dyn Query> = fs_cass_build_tantivy_query(raw_query, &fs_filters, fields);

        let prefix_only = is_prefix_only(sanitized_query);
        let top_docs = execute_query_with_lazy_exact_count(&searcher, &*q, limit, offset)?;
        let tantivy_total_count = top_docs.total_count;
        let query_match_type = dominant_match_type(sanitized_query);
        let mut pending_hits = Vec::with_capacity(top_docs.hits.len());
        let mut missing_exact_content_keys = Vec::new();
        let mut missing_fallback_content_keys = Vec::new();

        for ranked_hit in top_docs.hits {
            let score = ranked_hit.bm25_score;
            let doc: TantivyDocument = fs_load_doc(&searcher, ranked_hit.doc_address)?;
            let title = if field_mask.wants_title() {
                doc.get_first(fields.title)
                    .and_then(|v| v.as_str())
                    .unwrap_or("")
                    .to_string()
            } else {
                String::new()
            };
            let stored_content = doc
                .get_first(fields.content)
                .and_then(|v| v.as_str())
                .unwrap_or("")
                .to_string();
            let stored_preview = doc
                .get_first(fields.preview)
                .and_then(|v| v.as_str())
                .unwrap_or("")
                .to_string();
            let stored_preview_snippet = snippet_from_preview_without_full_content(
                field_mask,
                &stored_preview,
                sanitized_query,
            );
            let agent = doc
                .get_first(fields.agent)
                .and_then(|v| v.as_str())
                .unwrap_or("")
                .to_string();
            let workspace = doc
                .get_first(fields.workspace)
                .and_then(|v| v.as_str())
                .unwrap_or("")
                .to_string();
            let workspace_original = doc
                .get_first(fields.workspace_original)
                .and_then(|v| v.as_str())
                .filter(|s| !s.is_empty())
                .map(String::from);
            let created_at = doc.get_first(fields.created_at).and_then(|v| v.as_i64());
            let line_number = doc
                .get_first(fields.msg_idx)
                .and_then(|v| v.as_u64())
                .and_then(|i| usize::try_from(i).ok())
                .map(|i| i.saturating_add(1));
            let raw_source_id = doc
                .get_first(fields.source_id)
                .and_then(|v| v.as_str())
                .unwrap_or_default()
                .to_string();
            let conversation_id = fields
                .conversation_id
                .and_then(|field| doc.get_first(field))
                .and_then(|v| v.as_i64());
            let source_path = doc
                .get_first(fields.source_path)
                .and_then(|v| v.as_str())
                .unwrap_or("")
                .to_string();
            let raw_origin_kind = doc
                .get_first(fields.origin_kind)
                .and_then(|v| v.as_str())
                .map(str::to_string);
            let origin_host = doc
                .get_first(fields.origin_host)
                .and_then(|v| v.as_str())
                .filter(|s| !s.is_empty())
                .map(String::from);
            let source_id = normalized_search_hit_source_id_parts(
                raw_source_id.as_str(),
                raw_origin_kind.as_deref().unwrap_or_default(),
                origin_host.as_deref(),
            );

            let preview_satisfies_bounded_content =
                field_mask.preview_content_limit().is_some() && !stored_preview.is_empty();
            let preview_satisfies_full_content = field_mask.needs_content()
                && field_mask.preview_content_limit().is_none()
                && stored_preview_is_complete_content(&stored_preview);
            if needs_content
                && let Some(line_idx) = line_number
                    .and_then(|line| line.checked_sub(1))
                    .and_then(|line| i64::try_from(line).ok())
                && stored_content.is_empty()
                && !preview_satisfies_bounded_content
                && !preview_satisfies_full_content
                && stored_preview_snippet.is_none()
            {
                if let Some(conversation_id) = conversation_id {
                    missing_exact_content_keys.push((conversation_id, line_idx));
                } else {
                    missing_fallback_content_keys.push((
                        source_id.clone(),
                        source_path.clone(),
                        line_idx,
                    ));
                }
            }

            pending_hits.push(PendingTantivyHit {
                score,
                doc,
                title,
                stored_content,
                stored_preview,
                agent,
                source_path,
                workspace,
                workspace_original,
                created_at,
                line_number,
                stored_preview_snippet,
                source_id,
                conversation_id,
                raw_origin_kind,
                origin_host,
            });
        }

        let (hydrated_contents, hydrated_fallback_contents) = if needs_content
            && (!missing_exact_content_keys.is_empty() || !missing_fallback_content_keys.is_empty())
        {
            self.hydrate_tantivy_hit_contents(
                &missing_exact_content_keys,
                &missing_fallback_content_keys,
            )?
        } else {
            (HashMap::new(), HashMap::new())
        };
        let needs_tantivy_snippet_generator = wants_snippet
            && !prefix_only
            && pending_hits
                .iter()
                .any(|pending| pending.stored_preview_snippet.is_none());
        let snippet_generator = if needs_tantivy_snippet_generator {
            let snippet_cfg = FsSnippetConfig {
                max_chars: 160,
                highlight_prefix: "<b>".to_string(),
                highlight_postfix: "</b>".to_string(),
            };
            fs_try_build_snippet_generator(&searcher, &*q, fields.content, &snippet_cfg)
        } else {
            None
        };
        let mut hits = Vec::with_capacity(pending_hits.len());
        for pending in pending_hits {
            let hydrated_content = pending
                .line_number
                .and_then(|line| line.checked_sub(1))
                .and_then(|line| i64::try_from(line).ok())
                .and_then(|line_idx| {
                    if let Some(conversation_id) = pending.conversation_id {
                        hydrated_contents.get(&(conversation_id, line_idx)).cloned()
                    } else {
                        hydrated_fallback_contents
                            .get(&(
                                pending.source_id.clone(),
                                pending.source_path.clone(),
                                line_idx,
                            ))
                            .cloned()
                    }
                });
            let preview_satisfies_effective_content = !pending.stored_preview.is_empty()
                && (field_mask.preview_content_limit().is_some()
                    || (field_mask.needs_content()
                        && field_mask.preview_content_limit().is_none()
                        && stored_preview_is_complete_content(&pending.stored_preview)));
            let effective_content = if !pending.stored_content.is_empty() {
                pending.stored_content.clone()
            } else if preview_satisfies_effective_content {
                pending.stored_preview.clone()
            } else if let Some(content) = hydrated_content {
                content
            } else {
                pending.stored_preview.clone()
            };
            let snippet = if wants_snippet {
                if let Some(snippet) = pending.stored_preview_snippet.clone() {
                    snippet
                } else if let Some(r#gen) = &snippet_generator {
                    let rendered = if !pending.stored_content.is_empty() {
                        fs_render_snippet_html(r#gen, &pending.doc, "<b>", "</b>")
                    } else if !effective_content.is_empty() {
                        let mut snippet_doc = TantivyDocument::new();
                        snippet_doc.add_text(fields.content, &effective_content);
                        fs_render_snippet_html(r#gen, &snippet_doc, "<b>", "</b>")
                    } else {
                        None
                    };
                    rendered
                        .map(|html| html.replace("<b>", "**").replace("</b>", "**"))
                        .or_else(|| cached_prefix_snippet(&effective_content, sanitized_query, 160))
                        .unwrap_or_else(|| {
                            quick_prefix_snippet(&effective_content, sanitized_query, 160)
                        })
                } else if let Some(sn) =
                    cached_prefix_snippet(&effective_content, sanitized_query, 160)
                {
                    sn
                } else {
                    quick_prefix_snippet(&effective_content, sanitized_query, 160)
                }
            } else {
                String::new()
            };
            let content = if field_mask.needs_content() {
                effective_content.clone()
            } else {
                String::new()
            };
            let content_hash = stable_hit_hash(
                &effective_content,
                &pending.source_path,
                pending.line_number,
                pending.created_at,
            );
            let origin_kind = normalized_search_hit_origin_kind(
                &pending.source_id,
                pending.raw_origin_kind.as_deref(),
            )
            .to_string();
            hits.push(SearchHit {
                title: pending.title,
                snippet,
                content,
                content_hash,
                conversation_id: pending.conversation_id,
                score: pending.score,
                source_path: pending.source_path,
                agent: pending.agent,
                workspace: pending.workspace,
                workspace_original: pending.workspace_original,
                created_at: pending.created_at,
                line_number: pending.line_number,
                match_type: query_match_type,
                source_id: pending.source_id,
                origin_kind,
                origin_host: pending.origin_host,
            });
        }
        Ok((hits, tantivy_total_count))
    }

    #[allow(clippy::too_many_arguments)]
    fn search_tantivy_federated(
        &self,
        readers: &[FederatedIndexReader],
        raw_query: &str,
        sanitized_query: &str,
        filters: SearchFilters,
        limit: usize,
        field_mask: FieldMask,
    ) -> Result<(Vec<SearchHit>, usize)> {
        let mut ranked_hits = Vec::new();
        let mut total_count = 0usize;

        for (shard_index, shard) in readers.iter().enumerate() {
            let (shard_hits, shard_total_count) = self.search_tantivy(
                &shard.reader,
                &shard.fields,
                raw_query,
                sanitized_query,
                filters.clone(),
                limit,
                0,
                field_mask,
            )?;
            total_count = total_count.saturating_add(shard_total_count);
            for (shard_rank, hit) in shard_hits.into_iter().enumerate() {
                ranked_hits.push(FederatedRankedHit {
                    hit,
                    shard_index,
                    shard_rank,
                    fused_score: federated_rrf_score(shard_rank),
                });
            }
        }

        let raw_hit_count = ranked_hits.len();
        let generation_signature = self.federated_generation_signature(readers);
        self.track_generation(generation_signature);
        let combined_hits = merge_federated_ranked_hits(ranked_hits);
        tracing::debug!(
            generation_signature,
            shard_count = readers.len(),
            total_count,
            raw_hit_count,
            returned_hit_count = combined_hits.len(),
            merge_policy = "rrf_rank_then_stable_hit_key",
            "federated lexical search merged shard results"
        );

        Ok((combined_hits, total_count))
    }

    fn sqlite_fts_uses_message_id_column(conn: &Connection) -> Result<bool> {
        let params: [ParamValue; 0] = [];
        let ddl_rows: Vec<String> = franken_query_map_collect_retry(
            conn,
            "SELECT COALESCE(sql, '')
             FROM sqlite_master
             WHERE name = 'fts_messages'
             ORDER BY rowid DESC
             LIMIT 1",
            &params,
            |row: &frankensqlite::Row| row.get_typed::<String>(0),
        )?;
        Ok(ddl_rows
            .first()
            .map(|sql| sql.to_ascii_lowercase().contains("message_id"))
            .unwrap_or(false))
    }

    fn sqlite_fts_match_mode(conn: &Connection) -> Result<SqliteFtsMatchMode> {
        let params = [ParamValue::from("__cass_fts_probe_no_match__")];
        match franken_query_map_collect_retry(
            conn,
            "SELECT COUNT(*) FROM fts_messages WHERE fts_messages MATCH ?",
            &params,
            |row: &frankensqlite::Row| row.get_typed::<i64>(0),
        ) {
            Ok(_) => Ok(SqliteFtsMatchMode::Table),
            Err(err)
                if err
                    .to_string()
                    .contains("no such column: fts_messages in table fts_messages") =>
            {
                Ok(SqliteFtsMatchMode::IndexedColumns)
            }
            Err(err) => Err(anyhow!(err)),
        }
    }

    fn sqlite_fts5_rowid_projection_available(conn: &Connection) -> bool {
        let params: [ParamValue; 0] = [];
        franken_query_map_collect_retry(
            conn,
            "SELECT rowid FROM fts_messages LIMIT 1",
            &params,
            |row: &frankensqlite::Row| row.get_typed::<i64>(0),
        )
        .is_ok()
    }

    fn sqlite_fts5_match_clause(match_mode: SqliteFtsMatchMode) -> &'static str {
        match match_mode {
            SqliteFtsMatchMode::Table => "fts_messages MATCH ?",
            SqliteFtsMatchMode::IndexedColumns => {
                "(content MATCH ?
                  OR title MATCH ?
                  OR agent MATCH ?
                  OR workspace MATCH ?
                  OR source_path MATCH ?)"
            }
        }
    }

    fn push_sqlite_fts5_match_params(
        params: &mut Vec<ParamValue>,
        fts_query: &str,
        match_mode: SqliteFtsMatchMode,
    ) {
        let copies = match match_mode {
            SqliteFtsMatchMode::Table => 1,
            SqliteFtsMatchMode::IndexedColumns => 5,
        };
        for _ in 0..copies {
            params.push(ParamValue::from(fts_query));
        }
    }

    fn sqlite_fts5_rank_query(
        fts_query: &str,
        _filters: &SearchFilters,
        limit: usize,
        offset: usize,
        _uses_message_id: bool,
        match_mode: SqliteFtsMatchMode,
    ) -> (String, Vec<ParamValue>) {
        let match_clause = Self::sqlite_fts5_match_clause(match_mode);
        let mut sql = format!(
            "SELECT rowid,
                    bm25(fts_messages)
             FROM fts_messages
             WHERE {match_clause}"
        );
        let mut params = Vec::with_capacity(9);
        Self::push_sqlite_fts5_match_params(&mut params, fts_query, match_mode);

        sql.push_str(" ORDER BY bm25(fts_messages), rowid LIMIT ? OFFSET ?");
        params.push(ParamValue::from(limit as i64));
        params.push(ParamValue::from(offset as i64));

        (sql, params)
    }

    fn sqlite_fts5_hydrate_query(
        row_count: usize,
        field_mask: FieldMask,
        uses_message_id: bool,
    ) -> String {
        let title_expr = if field_mask.wants_title() {
            "fts_messages.title"
        } else {
            "NULL"
        };
        let content_expr = if field_mask.needs_content() || field_mask.wants_snippet() {
            "fts_messages.content"
        } else {
            "NULL"
        };
        let message_key_expr = if uses_message_id {
            "CAST(fts_messages.message_id AS INTEGER)"
        } else {
            "rowid"
        };
        let placeholders = sql_placeholders(row_count);

        format!(
            "SELECT rowid,
                    {message_key_expr},
                    {title_expr},
                    {content_expr},
                    fts_messages.agent,
                    fts_messages.workspace,
                    fts_messages.source_path,
                    CAST(fts_messages.created_at AS INTEGER)
             FROM fts_messages
             WHERE rowid IN ({placeholders})"
        )
    }

    fn sqlite_fts5_message_hydrate_query(row_count: usize, field_mask: FieldMask) -> String {
        let title_expr = if field_mask.wants_title() {
            "COALESCE(c.title, '')"
        } else {
            "''"
        };
        let content_expr = if field_mask.needs_content() || field_mask.wants_snippet() {
            "COALESCE(m.content, '')"
        } else {
            "''"
        };
        let normalized_source_sql =
            normalized_search_source_id_sql_expr("c.source_id", "s.kind", "c.origin_host");
        let placeholders = sql_placeholders(row_count);

        format!(
            "SELECT m.id,
                    {title_expr},
                    {content_expr},
                    COALESCE(a.slug, ''),
                    COALESCE(w.path, ''),
                    COALESCE(c.source_path, ''),
                    CAST(m.created_at AS INTEGER),
                    m.idx,
                    c.id,
                    {normalized_source_sql},
                    c.origin_host,
                    s.kind
             FROM messages m
             LEFT JOIN conversations c ON m.conversation_id = c.id
             LEFT JOIN sources s ON c.source_id = s.id
             LEFT JOIN agents a ON c.agent_id = a.id
             LEFT JOIN workspaces w ON c.workspace_id = w.id
             WHERE m.id IN ({placeholders})"
        )
    }

    fn sqlite_fts5_hydrate_row_chunks(
        ranked_rows: &[(i64, f64)],
    ) -> impl Iterator<Item = &[(i64, f64)]> {
        const _: () = assert!(SQLITE_FTS5_HYDRATE_PARAM_CHUNK <= SQLITE_MAX_VARIABLE_NUMBER);
        ranked_rows.chunks(SQLITE_FTS5_HYDRATE_PARAM_CHUNK)
    }

    fn sqlite_fts5_filters_need_post_hydration(filters: &SearchFilters) -> bool {
        !filters.agents.is_empty()
            || !filters.workspaces.is_empty()
            || filters.created_from.is_some()
            || filters.created_to.is_some()
            || !filters.source_filter.is_all()
            || !filters.session_paths.is_empty()
    }

    fn sqlite_fts5_hit_matches_filters(hit: &SearchHit, filters: &SearchFilters) -> bool {
        if !filters.agents.is_empty() && !filters.agents.contains(&hit.agent) {
            return false;
        }
        if !filters.workspaces.is_empty() && !filters.workspaces.contains(&hit.workspace) {
            return false;
        }
        if filters.created_from.is_some() || filters.created_to.is_some() {
            let Some(created_at) = hit.created_at else {
                return false;
            };
            if let Some(created_from) = filters.created_from
                && created_at < created_from
            {
                return false;
            }
            if let Some(created_to) = filters.created_to
                && created_at > created_to
            {
                return false;
            }
        }
        if !filters.session_paths.is_empty() && !filters.session_paths.contains(&hit.source_path) {
            return false;
        }

        match &filters.source_filter {
            SourceFilter::All => true,
            SourceFilter::Local => matches!(
                hit.source_id
                    .as_str()
                    .cmp(crate::sources::provenance::LOCAL_SOURCE_ID),
                CmpOrdering::Equal
            ),
            SourceFilter::Remote => !matches!(
                hit.source_id
                    .as_str()
                    .cmp(crate::sources::provenance::LOCAL_SOURCE_ID),
                CmpOrdering::Equal
            ),
            SourceFilter::SourceId(id) => {
                let normalized = normalize_search_source_filter_value(id);
                matches!(
                    hit.source_id.as_str().cmp(normalized.as_str()),
                    CmpOrdering::Equal
                )
            }
        }
    }

    fn sqlite_message_scan_query(raw_query: &str) -> Option<SqliteMessageScanQuery> {
        fn scan_parts(parts: Vec<String>) -> Vec<String> {
            parts
                .into_iter()
                .map(|part| part.trim_end_matches('*').to_lowercase())
                .filter(|part| !part.is_empty())
                .collect()
        }

        let tokens = fs_cass_parse_boolean_query(raw_query);
        if tokens.is_empty() {
            return None;
        }

        let mut include_groups = Vec::new();
        let mut pending_or_group: SqliteMessageScanGroup = Vec::new();
        let mut exclude_terms = Vec::new();
        let mut negated = false;
        let mut in_or_sequence = false;
        for token in tokens {
            match token {
                FsCassQueryToken::And => {
                    if !pending_or_group.is_empty() {
                        include_groups.push(std::mem::take(&mut pending_or_group));
                    }
                    in_or_sequence = false;
                    negated = false;
                }
                FsCassQueryToken::Or => {
                    if include_groups.is_empty() && pending_or_group.is_empty() {
                        continue;
                    }
                    if negated {
                        return None;
                    }
                    in_or_sequence = true;
                }
                FsCassQueryToken::Not => {
                    if in_or_sequence {
                        return None;
                    }
                    if !pending_or_group.is_empty() {
                        include_groups.push(std::mem::take(&mut pending_or_group));
                    }
                    negated = true;
                    in_or_sequence = false;
                }
                FsCassQueryToken::Term(term) => {
                    let parts = scan_parts(normalize_term_parts(&term));
                    if parts.is_empty() {
                        continue;
                    }
                    if negated {
                        exclude_terms.extend(parts);
                    } else if in_or_sequence {
                        if pending_or_group.is_empty() {
                            let previous = include_groups.pop()?;
                            pending_or_group.extend(previous);
                        }
                        pending_or_group.push(parts);
                    } else {
                        include_groups.push(vec![parts]);
                    }
                    negated = false;
                }
                FsCassQueryToken::Phrase(phrase) => {
                    let parts = normalize_phrase_terms(&phrase);
                    if parts.is_empty() {
                        continue;
                    }
                    if negated {
                        exclude_terms.extend(parts);
                    } else if in_or_sequence {
                        if pending_or_group.is_empty() {
                            let previous = include_groups.pop()?;
                            pending_or_group.extend(previous);
                        }
                        pending_or_group.push(parts);
                    } else {
                        include_groups.push(vec![parts]);
                    }
                    negated = false;
                }
            }
        }

        if !pending_or_group.is_empty() {
            include_groups.push(pending_or_group);
        }

        for group in &mut include_groups {
            for alternative in group.iter_mut() {
                alternative.sort();
                alternative.dedup();
            }
            group.retain(|alternative| !alternative.is_empty());
            group.sort();
            group.dedup();
        }
        include_groups.retain(|group| !group.is_empty());
        exclude_terms.sort();
        exclude_terms.dedup();
        if include_groups.is_empty() {
            return None;
        }

        Some(SqliteMessageScanQuery {
            include_groups,
            exclude_terms,
        })
    }

    fn sqlite_message_scan_score(haystack: &str, scan_query: &SqliteMessageScanQuery) -> f32 {
        for term in &scan_query.exclude_terms {
            if haystack.contains(term) {
                return 0.0;
            }
        }

        let mut score = 0.0f32;
        for group in &scan_query.include_groups {
            let mut group_score = 0.0f32;
            for alternative in group {
                let mut alternative_score = 0.0f32;
                for term in alternative {
                    let matches = haystack.matches(term).count();
                    if matches < 1 {
                        alternative_score = 0.0;
                        break;
                    }
                    alternative_score += matches as f32;
                }
                group_score = group_score.max(alternative_score);
            }
            if group_score <= 0.0 {
                return 0.0;
            }
            score += group_score;
        }
        score
    }

    fn sqlite_message_scan_query_sql(field_mask: FieldMask) -> String {
        let title_expr = if field_mask.wants_title() {
            "COALESCE(c.title, '')"
        } else {
            "''"
        };
        let content_expr = if field_mask.needs_content() || field_mask.wants_snippet() {
            "COALESCE(m.content, '')"
        } else {
            "''"
        };
        let normalized_source_sql =
            normalized_search_source_id_sql_expr("c.source_id", "s.kind", "c.origin_host");

        format!(
            "SELECT m.id,
                    {title_expr},
                    {content_expr},
                    COALESCE(a.slug, ''),
                    COALESCE(w.path, ''),
                    COALESCE(c.source_path, ''),
                    CAST(m.created_at AS INTEGER),
                    m.idx,
                    c.id,
                    {normalized_source_sql},
                    c.origin_host,
                    s.kind,
                    COALESCE(m.content, ''),
                    COALESCE(c.title, '')
             FROM messages m
             LEFT JOIN conversations c ON m.conversation_id = c.id
             LEFT JOIN sources s ON c.source_id = s.id
             LEFT JOIN agents a ON c.agent_id = a.id
             LEFT JOIN workspaces w ON c.workspace_id = w.id
             ORDER BY m.id
             LIMIT ?"
        )
    }

    fn search_sqlite_message_scan(
        &self,
        conn: &Connection,
        request: SqliteMessageScanRequest<'_>,
    ) -> Result<Vec<SearchHit>> {
        let Some(scan_query) = Self::sqlite_message_scan_query(request.raw_query) else {
            return Ok(Vec::new());
        };

        let sql = Self::sqlite_message_scan_query_sql(request.field_mask);
        let params = [ParamValue::from(SQLITE_MESSAGE_SCAN_FALLBACK_LIMIT as i64)];
        let rows: Vec<(SqliteFtsMessageRow, String, String)> =
            franken_query_map_collect_retry(conn, &sql, &params, |row| {
                Ok((
                    (
                        row.get_typed(0)?,
                        row.get_typed(1)?,
                        row.get_typed(2)?,
                        row.get_typed(3)?,
                        row.get_typed(4)?,
                        row.get_typed(5)?,
                        row.get_typed(6)?,
                        row.get_typed(7)?,
                        row.get_typed(8)?,
                        row.get_typed::<Option<String>>(9)?,
                        row.get_typed(10)?,
                        row.get_typed(11)?,
                    ),
                    row.get_typed(12)?,
                    row.get_typed(13)?,
                ))
            })?;

        let mut scored_hits = Vec::new();
        for (
            (
                _message_id,
                title,
                raw_content,
                agent,
                workspace,
                source_path,
                created_at,
                idx,
                conversation_id,
                raw_source_id,
                origin_host,
                raw_origin_kind,
            ),
            scan_content,
            scan_title,
        ) in rows
        {
            let mut haystack = String::with_capacity(
                scan_content.len()
                    + scan_title.len()
                    + agent.len()
                    + workspace.len()
                    + source_path.len()
                    + 4,
            );
            haystack.push_str(&scan_content);
            haystack.push(' ');
            haystack.push_str(&scan_title);
            haystack.push(' ');
            haystack.push_str(&agent);
            haystack.push(' ');
            haystack.push_str(&workspace);
            haystack.push(' ');
            haystack.push_str(&source_path);
            let haystack = haystack.to_lowercase();
            let score = Self::sqlite_message_scan_score(&haystack, &scan_query);
            if score <= 0.0 {
                continue;
            }

            let raw_source_id = raw_source_id.unwrap_or_else(default_source_id);
            let source_id = normalized_search_hit_source_id_parts(
                raw_source_id.as_str(),
                raw_origin_kind.as_deref().unwrap_or_default(),
                origin_host.as_deref(),
            );
            let origin_kind =
                normalized_search_hit_origin_kind(source_id.as_str(), raw_origin_kind.as_deref());
            let line_number = idx
                .and_then(|i| usize::try_from(i).ok())
                .map(|i| i.saturating_add(1));
            let snippet = if request.field_mask.wants_snippet() {
                snippet_from_content(&scan_content)
            } else {
                String::new()
            };
            let content = if request.field_mask.needs_content() {
                raw_content
            } else {
                String::new()
            };
            let content_hash = if content.is_empty() {
                stable_hit_hash(&snippet, &source_path, line_number, created_at)
            } else {
                stable_hit_hash(&content, &source_path, line_number, created_at)
            };

            let hit = SearchHit {
                title,
                snippet,
                content,
                content_hash,
                conversation_id,
                score,
                source_path,
                agent,
                workspace,
                workspace_original: None,
                created_at,
                line_number,
                match_type: request.query_match_type,
                source_id,
                origin_kind,
                origin_host,
            };

            if Self::sqlite_fts5_hit_matches_filters(&hit, request.filters) {
                scored_hits.push(hit);
            }
        }

        scored_hits.sort_by(|left, right| {
            right
                .score
                .partial_cmp(&left.score)
                .unwrap_or(CmpOrdering::Equal)
        });

        Ok(scored_hits
            .into_iter()
            .skip(request.offset)
            .take(request.limit)
            .collect())
    }

    fn search_sqlite_fts5(
        &self,
        _db_path: &Path,
        raw_query: &str,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        field_mask: FieldMask,
    ) -> Result<Vec<SearchHit>> {
        if limit < 1 {
            return Ok(Vec::new());
        }

        let fts_query = match transpile_to_fts5(raw_query) {
            Some(q) if !q.trim().is_empty() => q,
            _ => return Ok(Vec::new()),
        };

        let sqlite_guard = self.sqlite_guard()?;
        let Some(conn) = sqlite_guard.as_ref() else {
            return Ok(Vec::new());
        };

        let empty_params: [ParamValue; 0] = [];
        let has_fts = franken_query_map_collect_retry(
            conn,
            "SELECT 1 FROM sqlite_master WHERE name = 'fts_messages'",
            &empty_params,
            |row| row.get_typed::<i64>(0),
        )
        .map(|rows| !rows.is_empty())
        .unwrap_or(false);
        if !has_fts {
            return Ok(Vec::new());
        }

        let query_match_type = dominant_match_type(raw_query);
        let scan_request = SqliteMessageScanRequest {
            raw_query,
            filters: &filters,
            limit,
            offset,
            field_mask,
            query_match_type,
        };
        let uses_message_id =
            if let Ok(uses_message_id) = Self::sqlite_fts_uses_message_id_column(conn) {
                uses_message_id
            } else {
                tracing::warn!(
                    "sqlite FTS fallback is present but not queryable; skipping fallback search"
                );
                return self.search_sqlite_message_scan(conn, scan_request);
            };
        let match_mode = match Self::sqlite_fts_match_mode(conn) {
            Ok(match_mode) => match_mode,
            Err(err) => {
                tracing::warn!(
                    error = %err,
                    "sqlite FTS fallback is present but not queryable; skipping fallback search"
                );
                return self.search_sqlite_message_scan(conn, scan_request);
            }
        };
        if !Self::sqlite_fts5_rowid_projection_available(conn) {
            tracing::warn!(
                "sqlite FTS fallback cannot project rowid through frankensqlite; using source-table scan fallback"
            );
            return self.search_sqlite_message_scan(conn, scan_request);
        }

        let post_filter = Self::sqlite_fts5_filters_need_post_hydration(&filters);
        let target_hits = if post_filter {
            offset.saturating_add(limit)
        } else {
            limit
        };
        let rank_batch_limit = if post_filter {
            target_hits.clamp(1, SQLITE_FTS5_POST_FILTER_SCAN_CHUNK)
        } else {
            limit
        };
        let mut rank_offset = if post_filter { 0 } else { offset };
        let mut scanned_rows = 0usize;
        let mut hits = Vec::with_capacity(target_hits.min(rank_batch_limit));

        loop {
            let (rank_sql, rank_params) = Self::sqlite_fts5_rank_query(
                fts_query.as_str(),
                &filters,
                rank_batch_limit,
                rank_offset,
                uses_message_id,
                match_mode,
            );
            let ranked_rows: Vec<(i64, f64)> =
                match franken_query_map_collect_retry(conn, &rank_sql, &rank_params, |row| {
                    Ok((row.get_typed(0)?, row.get_typed(1)?))
                }) {
                    Ok(rows) => rows,
                    Err(err) => {
                        tracing::warn!(
                            error = %err,
                            "sqlite FTS fallback rank query failed; returning no fallback hits"
                        );
                        return self.search_sqlite_message_scan(conn, scan_request);
                    }
                };
            if ranked_rows.is_empty() {
                break;
            }

            scanned_rows = scanned_rows.saturating_add(ranked_rows.len());
            let bm25_by_rowid: HashMap<i64, f64> = ranked_rows.iter().copied().collect();
            let mut fts_rows_by_rowid = HashMap::with_capacity(ranked_rows.len());
            let mut message_ids = Vec::with_capacity(ranked_rows.len());
            let mut seen_message_ids = HashSet::with_capacity(ranked_rows.len());

            for rank_chunk in Self::sqlite_fts5_hydrate_row_chunks(&ranked_rows) {
                let hydrate_sql =
                    Self::sqlite_fts5_hydrate_query(rank_chunk.len(), field_mask, uses_message_id);
                let hydrate_params = rank_chunk
                    .iter()
                    .map(|(fts_rowid, _)| ParamValue::from(*fts_rowid))
                    .collect::<Vec<_>>();
                let rows: Vec<SqliteFtsHydratedRow> = match franken_query_map_collect_retry(
                    conn,
                    &hydrate_sql,
                    &hydrate_params,
                    |row| {
                        Ok((
                            row.get_typed(0)?,
                            row.get_typed(1)?,
                            row.get_typed(2)?,
                            row.get_typed(3)?,
                            row.get_typed(4)?,
                            row.get_typed(5)?,
                            row.get_typed(6)?,
                            row.get_typed(7)?,
                        ))
                    },
                ) {
                    Ok(rows) => rows,
                    Err(err) => {
                        tracing::warn!(
                            error = %err,
                            "sqlite FTS fallback rowid hydration query failed; returning no fallback hits"
                        );
                        return self.search_sqlite_message_scan(conn, scan_request);
                    }
                };

                for row in rows {
                    let fts_rowid = row.0;
                    let message_id = row.1.unwrap_or(fts_rowid);
                    if seen_message_ids.insert(message_id) {
                        message_ids.push(message_id);
                    }
                    fts_rows_by_rowid.insert(fts_rowid, row);
                }
            }

            let mut metadata_by_message_id = HashMap::with_capacity(message_ids.len());
            for message_chunk in message_ids.chunks(SQLITE_FTS5_HYDRATE_PARAM_CHUNK) {
                let metadata_sql =
                    Self::sqlite_fts5_message_hydrate_query(message_chunk.len(), field_mask);
                let metadata_params = message_chunk
                    .iter()
                    .map(|message_id| ParamValue::from(*message_id))
                    .collect::<Vec<_>>();
                let metadata_rows: Vec<SqliteFtsMessageRow> = match franken_query_map_collect_retry(
                    conn,
                    &metadata_sql,
                    &metadata_params,
                    |row| {
                        Ok((
                            row.get_typed(0)?,
                            row.get_typed(1)?,
                            row.get_typed(2)?,
                            row.get_typed(3)?,
                            row.get_typed(4)?,
                            row.get_typed(5)?,
                            row.get_typed(6)?,
                            row.get_typed(7)?,
                            row.get_typed(8)?,
                            row.get_typed::<Option<String>>(9)?,
                            row.get_typed(10)?,
                            row.get_typed(11)?,
                        ))
                    },
                ) {
                    Ok(rows) => rows,
                    Err(err) => {
                        tracing::warn!(
                            error = %err,
                            "sqlite FTS fallback message hydration query failed; returning no fallback hits"
                        );
                        return self.search_sqlite_message_scan(conn, scan_request);
                    }
                };
                metadata_by_message_id.extend(metadata_rows.into_iter().map(|row| (row.0, row)));
            }

            let mut hits_by_rowid = HashMap::with_capacity(ranked_rows.len());
            for (
                fts_rowid,
                fts_message_id,
                fts_title,
                fts_content,
                fts_agent,
                fts_workspace,
                fts_source_path,
                fts_created_at,
            ) in fts_rows_by_rowid.into_values()
            {
                let Some(&bm25_score) = bm25_by_rowid.get(&fts_rowid) else {
                    continue;
                };
                let message_id = fts_message_id.unwrap_or(fts_rowid);
                let (
                    title,
                    raw_content,
                    agent,
                    workspace,
                    source_path,
                    created_at,
                    idx,
                    conversation_id,
                    raw_source_id,
                    origin_host,
                    raw_origin_kind,
                ) = match metadata_by_message_id.remove(&message_id) {
                    Some((
                        _,
                        metadata_title,
                        metadata_content,
                        metadata_agent,
                        metadata_workspace,
                        metadata_source_path,
                        metadata_created_at,
                        metadata_idx,
                        metadata_conversation_id,
                        metadata_raw_source_id,
                        metadata_origin_host,
                        metadata_raw_origin_kind,
                    )) => (
                        if metadata_title.is_empty() {
                            fts_title.unwrap_or_default()
                        } else {
                            metadata_title
                        },
                        if metadata_content.is_empty() {
                            fts_content.unwrap_or_default()
                        } else {
                            metadata_content
                        },
                        if metadata_agent.is_empty() {
                            fts_agent.unwrap_or_default()
                        } else {
                            metadata_agent
                        },
                        if metadata_workspace.is_empty() {
                            fts_workspace.unwrap_or_default()
                        } else {
                            metadata_workspace
                        },
                        if metadata_source_path.is_empty() {
                            fts_source_path.unwrap_or_default()
                        } else {
                            metadata_source_path
                        },
                        metadata_created_at.or(fts_created_at),
                        metadata_idx,
                        metadata_conversation_id,
                        metadata_raw_source_id.unwrap_or_else(default_source_id),
                        metadata_origin_host,
                        metadata_raw_origin_kind,
                    ),
                    None => (
                        fts_title.unwrap_or_default(),
                        fts_content.unwrap_or_default(),
                        fts_agent.unwrap_or_default(),
                        fts_workspace.unwrap_or_default(),
                        fts_source_path.unwrap_or_default(),
                        fts_created_at,
                        None,
                        None,
                        default_source_id(),
                        None,
                        None,
                    ),
                };

                let source_id = normalized_search_hit_source_id_parts(
                    raw_source_id.as_str(),
                    raw_origin_kind.as_deref().unwrap_or_default(),
                    origin_host.as_deref(),
                );
                let origin_kind = normalized_search_hit_origin_kind(
                    source_id.as_str(),
                    raw_origin_kind.as_deref(),
                );
                let line_number = idx
                    .and_then(|i| usize::try_from(i).ok())
                    .map(|i| i.saturating_add(1));
                let snippet = if field_mask.wants_snippet() {
                    snippet_from_content(&raw_content)
                } else {
                    String::new()
                };
                let content = if field_mask.needs_content() {
                    raw_content
                } else {
                    String::new()
                };
                let content_hash = if content.is_empty() {
                    stable_hit_hash(&snippet, &source_path, line_number, created_at)
                } else {
                    stable_hit_hash(&content, &source_path, line_number, created_at)
                };

                let hit = SearchHit {
                    title,
                    snippet,
                    content,
                    content_hash,
                    conversation_id,
                    score: (-bm25_score) as f32,
                    source_path,
                    agent,
                    workspace,
                    workspace_original: None,
                    created_at,
                    line_number,
                    match_type: query_match_type,
                    source_id,
                    origin_kind,
                    origin_host,
                };
                hits_by_rowid.insert(fts_rowid, hit);
            }

            for (fts_rowid, _) in &ranked_rows {
                if let Some(hit) = hits_by_rowid.remove(fts_rowid)
                    && Self::sqlite_fts5_hit_matches_filters(&hit, &filters)
                {
                    hits.push(hit);
                    if hits.len() >= target_hits {
                        break;
                    }
                }
            }

            if hits.len() >= target_hits
                || !post_filter
                || ranked_rows.len() < rank_batch_limit
                || scanned_rows >= SQLITE_FTS5_POST_FILTER_SCAN_LIMIT
            {
                break;
            }
            rank_offset = rank_offset.saturating_add(ranked_rows.len());
        }

        if post_filter {
            let hits = hits
                .into_iter()
                .skip(offset)
                .take(limit)
                .collect::<Vec<_>>();
            if hits.is_empty() {
                self.search_sqlite_message_scan(conn, scan_request)
            } else {
                Ok(hits)
            }
        } else if hits.is_empty() {
            self.search_sqlite_message_scan(conn, scan_request)
        } else {
            Ok(hits)
        }
    }

    /// Browse messages ordered by date, without any text query.
    ///
    /// Used when the TUI query is empty and the user wants to see recent (or
    /// oldest) sessions. Bypasses BM25 scoring entirely and returns results
    /// ordered by `created_at`. Applies agent, workspace, time-range, and
    /// source filters identically to the normal search path.
    pub fn browse_by_date(
        &self,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        newest_first: bool,
        field_mask: FieldMask,
    ) -> Result<Vec<SearchHit>> {
        let sqlite_guard = self.sqlite_guard()?;
        if let Some(conn) = sqlite_guard.as_ref() {
            self.browse_by_date_sqlite(conn, filters, limit, offset, newest_first, field_mask)
        } else {
            Ok(Vec::new())
        }
    }

    fn browse_by_date_sqlite(
        &self,
        conn: &Connection,
        filters: SearchFilters,
        limit: usize,
        offset: usize,
        newest_first: bool,
        field_mask: FieldMask,
    ) -> Result<Vec<SearchHit>> {
        let order = if newest_first { "DESC" } else { "ASC" };
        let title_expr = if field_mask.wants_title() {
            "c.title"
        } else {
            "''"
        };
        // Replace INNER JOIN agents with a correlated subquery: (a) avoids
        // frankensqlite's multi-table-JOIN-with-LIMIT/OFFSET materialization
        // fallback on every paginated search, and (b) stops silently dropping
        // search hits whose conversation has a NULL agent_id (legacy V1 rows)
        // by degrading to 'unknown' consistently with e1c08e7c / 8a0c547c.
        // The agent filter below becomes an EXISTS guard instead of a slug
        // equality on the joined column.
        let normalized_source_sql =
            normalized_search_source_id_sql_expr("c.source_id", "s.kind", "c.origin_host");
        let mut sql = format!(
            "SELECT c.id, {title_expr}, m.content, \
                 COALESCE((SELECT a.slug FROM agents a WHERE a.id = c.agent_id), 'unknown'), \
                 w.path, c.source_path, m.created_at, m.idx, \
                 {normalized_source_sql}, c.origin_host, s.kind
             FROM messages m
             JOIN conversations c ON m.conversation_id = c.id
             LEFT JOIN workspaces w ON c.workspace_id = w.id
             LEFT JOIN sources s ON c.source_id = s.id
             WHERE 1=1"
        );
        let mut params: Vec<ParamValue> = Vec::new();

        if !filters.agents.is_empty() {
            let placeholders = sql_placeholders(filters.agents.len());
            sql.push_str(&format!(
                " AND EXISTS (SELECT 1 FROM agents a WHERE a.id = c.agent_id AND a.slug IN ({placeholders}))"
            ));
            for a in &filters.agents {
                params.push(ParamValue::from(a.as_str()));
            }
        }

        if !filters.workspaces.is_empty() {
            let placeholders = sql_placeholders(filters.workspaces.len());
            sql.push_str(&format!(" AND COALESCE(w.path, '') IN ({placeholders})"));
            for w in &filters.workspaces {
                params.push(ParamValue::from(w.as_str()));
            }
        }

        if let Some(created_from) = filters.created_from {
            sql.push_str(" AND m.created_at >= ?");
            params.push(ParamValue::from(created_from));
        }
        if let Some(created_to) = filters.created_to {
            sql.push_str(" AND m.created_at <= ?");
            params.push(ParamValue::from(created_to));
        }

        // Apply source filter
        match &filters.source_filter {
            SourceFilter::All => {}
            SourceFilter::Local => sql.push_str(&format!(
                " AND {normalized_source_sql} = '{local}'",
                local = crate::sources::provenance::LOCAL_SOURCE_ID,
            )),
            SourceFilter::Remote => sql.push_str(&format!(
                " AND {normalized_source_sql} != '{local}'",
                local = crate::sources::provenance::LOCAL_SOURCE_ID,
            )),
            SourceFilter::SourceId(id) => {
                sql.push_str(&format!(" AND {normalized_source_sql} = ?"));
                params.push(ParamValue::from(normalize_search_source_filter_value(id)));
            }
        }

        sql.push_str(&format!(
            " ORDER BY CASE WHEN m.created_at IS NULL THEN 1 ELSE 0 END, m.created_at {order}, m.id {order} LIMIT ? OFFSET ?"
        ));
        params.push(ParamValue::from(limit as i64));
        params.push(ParamValue::from(offset as i64));

        let rows: Vec<SearchHit> =
            conn.query_map_collect(&sql, &params, |row: &frankensqlite::Row| {
                let conversation_id: i64 = row.get_typed(0)?;
                let title: String = if field_mask.wants_title() {
                    row.get_typed::<Option<String>>(1)?.unwrap_or_default()
                } else {
                    String::new()
                };
                let raw_content: String = row.get_typed(2)?;
                let agent: String = row.get_typed(3)?;
                let workspace: Option<String> = row.get_typed(4)?;
                let source_path: String = row.get_typed(5)?;
                let created_at: Option<i64> = row.get_typed(6)?;
                let idx: Option<i64> = row.get_typed(7)?;
                let raw_source_id: String = row
                    .get_typed::<Option<String>>(8)?
                    .unwrap_or_else(default_source_id);
                let origin_host: Option<String> = row.get_typed(9)?;
                let raw_origin_kind: Option<String> = row.get_typed(10)?;
                let source_id = normalized_search_hit_source_id_parts(
                    raw_source_id.as_str(),
                    raw_origin_kind.as_deref().unwrap_or_default(),
                    origin_host.as_deref(),
                );
                let origin_kind = normalized_search_hit_origin_kind(
                    source_id.as_str(),
                    raw_origin_kind.as_deref(),
                );
                let line_number = idx
                    .and_then(|i| usize::try_from(i).ok())
                    .map(|i| i.saturating_add(1));
                let snippet = if field_mask.wants_snippet() {
                    snippet_from_content(&raw_content)
                } else {
                    String::new()
                };
                let content = if field_mask.needs_content() {
                    raw_content.clone()
                } else {
                    String::new()
                };
                let content_hash =
                    stable_hit_hash(&raw_content, &source_path, line_number, created_at);
                Ok(SearchHit {
                    title,
                    snippet,
                    content,
                    content_hash,
                    conversation_id: Some(conversation_id),
                    score: 0.0,
                    source_path,
                    agent,
                    workspace: workspace.unwrap_or_default(),
                    workspace_original: None,
                    created_at,
                    line_number,
                    match_type: MatchType::Exact,
                    source_id,
                    origin_kind,
                    origin_host,
                })
            })?;
        Ok(rows)
    }
}

/// Fuzz-only re-export of `transpile_to_fts5` so
/// `fuzz_targets/fuzz_query_transpiler.rs` can exercise the
/// user-reachable query-rewriting path (bead
/// `coding_agent_session_search-ugp09`). `#[doc(hidden)]` keeps it
/// off the public API surface — callers outside the fuzz harness
/// should go through `QueryExplanation::analyze` or `SearchClient`.
#[doc(hidden)]
pub fn fuzz_transpile_to_fts5(raw_query: &str) -> Option<String> {
    transpile_to_fts5(raw_query)
}

/// Transpile a raw query string into an FTS5-compatible query string.
/// Preserves custom precedence (OR > AND) by adding parentheses.
/// Returns None if the query contains features unsupported by FTS5 (e.g. leading wildcards).
fn transpile_to_fts5(raw_query: &str) -> Option<String> {
    let tokens = fs_cass_parse_boolean_query(raw_query);
    if tokens.is_empty() {
        return Some("".to_string());
    }

    let mut fts_clauses: Vec<(&str, String)> = Vec::new();
    let mut pending_or_group: Vec<String> = Vec::new();
    let mut next_op = "AND";
    let mut in_or_sequence = false;
    for token in tokens {
        match token {
            FsCassQueryToken::And => {
                if !pending_or_group.is_empty() {
                    let group = if pending_or_group.len() > 1 {
                        format!("({})", pending_or_group.join(" OR "))
                    } else {
                        pending_or_group.pop().unwrap_or_default()
                    };
                    fts_clauses.push(("AND", group));
                    pending_or_group.clear();
                }
                in_or_sequence = false;
                next_op = "AND";
            }
            FsCassQueryToken::Or => {
                if fts_clauses.is_empty() && pending_or_group.is_empty() {
                    // Be permissive with a leading OR the same way we already
                    // salvage a leading AND: ignore it instead of turning the
                    // whole fallback query into an empty result set.
                    continue;
                }
                // Start or continue an OR group. Unsupported `OR NOT` forms
                // are rejected when the subsequent NOT token arrives.
                in_or_sequence = true;
            }
            FsCassQueryToken::Not => {
                // FTS5 supports binary (`foo NOT bar`) NOT, but not a leading
                // unary-NOT query (`NOT foo`). We also reject `OR NOT` groupings
                // in the fallback transpiler.
                if in_or_sequence {
                    return None;
                }

                if fts_clauses.is_empty() && pending_or_group.is_empty() {
                    return None;
                }

                if !pending_or_group.is_empty() {
                    let group = if pending_or_group.len() > 1 {
                        format!("({})", pending_or_group.join(" OR "))
                    } else {
                        pending_or_group.pop().unwrap_or_default()
                    };
                    fts_clauses.push(("AND", group));
                    pending_or_group.clear();
                }
                in_or_sequence = false;
                next_op = "NOT";
            }
            FsCassQueryToken::Term(t) => {
                let raw_pattern = FsCassWildcardPattern::parse(&t);
                if matches!(
                    raw_pattern,
                    FsCassWildcardPattern::Suffix(_)
                        | FsCassWildcardPattern::Substring(_)
                        | FsCassWildcardPattern::Complex(_)
                ) {
                    return None;
                }

                // Sanitize and normalize. FTS5 implicitly ANDs words in a string,
                // but we split punctuation into porter-aligned fragments first so
                // fallback queries match SQLite tokenization.
                let term_parts = normalize_term_parts(&t);
                if term_parts.is_empty() {
                    continue;
                }

                let mut rendered_parts = Vec::with_capacity(term_parts.len());
                for part in &term_parts {
                    rendered_parts.push(render_fts5_term_part(part)?);
                }

                // If multiple parts, wrap in parens and join with AND so a
                // punctuated term like `foo-bar` becomes `(foo AND bar)`.
                let fts_term = if rendered_parts.len() > 1 {
                    format!("({})", rendered_parts.join(" AND "))
                } else {
                    rendered_parts[0].clone()
                };

                if in_or_sequence {
                    if pending_or_group.is_empty() {
                        let (op, _) = fts_clauses.last()?;
                        if *op != "AND" {
                            // `(... NOT ...) OR ...` cannot be represented
                            // with our FTS5 fallback transpilation.
                            return None;
                        }
                        let (_, val) = fts_clauses.pop()?;
                        pending_or_group.push(val);
                    }
                    pending_or_group.push(fts_term);
                    in_or_sequence = true;
                } else {
                    fts_clauses.push((next_op, fts_term));
                }
                next_op = "AND";
            }
            FsCassQueryToken::Phrase(p) => {
                let phrase_parts = normalize_phrase_terms(&p);
                if phrase_parts.is_empty() {
                    continue;
                }
                let fts_phrase = format!("\"{}\"", phrase_parts.join(" "));

                if in_or_sequence {
                    if pending_or_group.is_empty() {
                        let (op, _) = fts_clauses.last()?;
                        if *op != "AND" {
                            // `(... NOT ...) OR ...` cannot be represented
                            // with our FTS5 fallback transpilation.
                            return None;
                        }
                        let (_, val) = fts_clauses.pop()?;
                        pending_or_group.push(val);
                    }
                    pending_or_group.push(fts_phrase);
                    in_or_sequence = true;
                } else {
                    fts_clauses.push((next_op, fts_phrase));
                }
                next_op = "AND";
            }
        }
    }

    if !pending_or_group.is_empty() {
        let group = if pending_or_group.len() > 1 {
            format!("({})", pending_or_group.join(" OR "))
        } else {
            pending_or_group.pop().unwrap_or_default()
        };
        fts_clauses.push((next_op, group));
    }

    if fts_clauses.is_empty() {
        return Some("".to_string());
    }

    // Safety guard: the fallback transpiler must never emit NOT as the first
    // operator because SQLite FTS5 requires a left operand.
    if fts_clauses.first().is_some_and(|(op, _)| *op == "NOT") {
        return None;
    }

    // Join clauses. The first operator is ignored (start of query).
    let mut query = String::new();
    for (i, (op, text)) in fts_clauses.into_iter().enumerate() {
        if i > 0 {
            query.push_str(&format!(" {} ", op));
        }
        query.push_str(&text);
    }

    Some(query)
}

#[derive(Default, Clone)]
struct Metrics {
    cache_hits: Arc<AtomicU64>,
    cache_miss: Arc<AtomicU64>,
    cache_shortfall: Arc<AtomicU64>,
    reloads: Arc<AtomicU64>,
    reload_ms_total: Arc<AtomicU64>,
    prewarm_scheduled: Arc<AtomicU64>,
    prewarm_skipped_pressure: Arc<AtomicU64>,
}

impl Metrics {
    fn inc_cache_hits(&self) {
        self.cache_hits.fetch_add(1, Ordering::Relaxed);
    }
    fn inc_cache_miss(&self) {
        self.cache_miss.fetch_add(1, Ordering::Relaxed);
    }
    fn inc_cache_shortfall(&self) {
        self.cache_shortfall.fetch_add(1, Ordering::Relaxed);
    }
    fn inc_prewarm_scheduled(&self) {
        self.prewarm_scheduled.fetch_add(1, Ordering::Relaxed);
    }
    fn inc_prewarm_skipped_pressure(&self) {
        self.prewarm_skipped_pressure
            .fetch_add(1, Ordering::Relaxed);
    }
    fn inc_reload(&self) {
        self.reloads.fetch_add(1, Ordering::Relaxed);
    }
    fn record_reload(&self, duration: Duration) {
        self.inc_reload();
        self.reload_ms_total
            .fetch_add(duration.as_millis() as u64, Ordering::Relaxed);
    }

    fn snapshot_all(&self) -> (u64, u64, u64, u64, u128) {
        (
            self.cache_hits.load(Ordering::Relaxed),
            self.cache_miss.load(Ordering::Relaxed),
            self.cache_shortfall.load(Ordering::Relaxed),
            self.reloads.load(Ordering::Relaxed),
            self.reload_ms_total.load(Ordering::Relaxed) as u128,
        )
    }

    fn snapshot_prewarm(&self) -> (u64, u64) {
        (
            self.prewarm_scheduled.load(Ordering::Relaxed),
            self.prewarm_skipped_pressure.load(Ordering::Relaxed),
        )
    }

    #[cfg(test)]
    #[allow(dead_code)]
    fn reset(&self) {
        self.cache_hits.store(0, Ordering::Relaxed);
        self.cache_miss.store(0, Ordering::Relaxed);
        self.cache_shortfall.store(0, Ordering::Relaxed);
        self.reloads.store(0, Ordering::Relaxed);
        self.reload_ms_total.store(0, Ordering::Relaxed);
        self.prewarm_scheduled.store(0, Ordering::Relaxed);
        self.prewarm_skipped_pressure.store(0, Ordering::Relaxed);
    }
}

fn maybe_spawn_warm_worker(
    reader: IndexReader,
    fields: FsCassFields,
    reload_epoch: Arc<AtomicU64>,
    metrics: Metrics,
) -> Option<(mpsc::Sender<WarmJob>, std::thread::JoinHandle<()>)> {
    let (tx, rx) = mpsc::unbounded::<WarmJob>();
    let handle = std::thread::Builder::new()
        .name("cass-warm-worker".into())
        .spawn(move || {
            // Simple debounce: process at most one warmup every WARM_DEBOUNCE_MS.
            let mut last_run = Instant::now();
            while let Ok(job) = rx.recv() {
                let now = Instant::now();
                if now.duration_since(last_run) < Duration::from_millis(*WARM_DEBOUNCE_MS) {
                    continue;
                }
                last_run = now;
                let reload_started = Instant::now();
                if let Err(err) = reader.reload() {
                    tracing::warn!(error = ?err, "warm_worker_reload_failed");
                    continue;
                }
                let elapsed = reload_started.elapsed();
                let epoch = reload_epoch.fetch_add(1, Ordering::SeqCst) + 1;
                metrics.record_reload(elapsed);
                tracing::debug!(
                    duration_ms = elapsed.as_millis() as u64,
                    reload_epoch = epoch,
                    filters = %job.filters_fingerprint,
                    shard = %job.shard_name,
                    "warm_worker_reload"
                );
                // Run a tiny warm search to prefill OS cache and hit the Tantivy reader
                // without allocating full result sets. Limit 1 doc.
                let searcher = reader.searcher();
                let mut clauses: Vec<(Occur, Box<dyn Query>)> = Vec::new();
                for term_str in job.query.split_whitespace() {
                    let term_lower = term_str.to_lowercase();
                    let term_shoulds: Vec<(Occur, Box<dyn Query>)> = vec![
                        (
                            Occur::Should,
                            Box::new(TermQuery::new(
                                Term::from_field_text(fields.title, &term_lower),
                                IndexRecordOption::WithFreqsAndPositions,
                            )),
                        ),
                        (
                            Occur::Should,
                            Box::new(TermQuery::new(
                                Term::from_field_text(fields.content, &term_lower),
                                IndexRecordOption::WithFreqsAndPositions,
                            )),
                        ),
                    ];
                    clauses.push((Occur::Must, Box::new(BooleanQuery::new(term_shoulds))));
                }
                if !clauses.is_empty() {
                    let q: Box<dyn Query> = Box::new(BooleanQuery::new(clauses));
                    let _ = searcher.search(&q, &TopDocs::with_limit(1).order_by_score());
                }
            }
        })
        .ok()?;
    Some((tx, handle))
}

fn cached_hit_from(hit: &SearchHit) -> CachedHit {
    let cache_text = if hit.content.is_empty() {
        hit.snippet.as_str()
    } else {
        hit.content.as_str()
    };
    let lc_content = cache_text.to_lowercase();
    let lc_title = (!hit.title.is_empty()).then(|| hit.title.to_lowercase());
    // Snippet is derived from content, so we don't index/bloom it separately
    let bloom64 = bloom_from_text(&lc_content, &lc_title);
    CachedHit {
        hit: hit.clone(),
        lc_content,
        lc_title,
        bloom64,
    }
}

fn bloom_from_text(content: &str, title: &Option<String>) -> u64 {
    let mut bits = 0u64;
    for token in token_stream(content) {
        bits |= hash_token(token);
    }
    if let Some(t) = title {
        for token in token_stream(t) {
            bits |= hash_token(token);
        }
    }
    bits
}

fn token_stream(text: &str) -> impl Iterator<Item = &str> {
    text.split(|c: char| !c.is_alphanumeric())
        .filter(|s| !s.is_empty())
}

fn hash_token(tok: &str) -> u64 {
    // Simple 64-bit djb2-style hash mapped to bit position 0..63
    let mut h: u64 = 5381;
    for b in tok.as_bytes() {
        h = ((h << 5).wrapping_add(h)).wrapping_add(u64::from(*b));
    }
    1u64 << (h % 64)
}

// ============================================================================
// QueryTermsLower: Pre-computed lowercase query tokens (Opt 2.4)
// ============================================================================
//
// Avoids repeated to_lowercase() calls when filtering many cached hits.
// The query is lowercased once and tokens extracted once, then reused.

/// Pre-computed lowercase query terms for efficient hit matching.
/// Call `from_query` once, then reuse for all hits in a search.
struct QueryTermsLower {
    /// The lowercased query string (owned to keep tokens valid)
    query_lower: String,
    /// Pre-computed token positions (start, end) into query_lower
    token_ranges: Vec<(usize, usize)>,
    /// Pre-computed bloom bits for fast rejection
    bloom_mask: u64,
}

impl QueryTermsLower {
    /// Create from a query string, pre-computing lowercase and tokens.
    fn from_query(query: &str) -> Self {
        if query.is_empty() {
            return Self {
                query_lower: String::new(),
                token_ranges: Vec::new(),
                bloom_mask: 0,
            };
        }

        let query_lower = query.to_lowercase();
        let mut token_ranges = Vec::new();
        let mut bloom_mask = 0u64;

        // Extract token positions
        let mut start = None;
        for (i, c) in query_lower.char_indices() {
            if c.is_alphanumeric() {
                if start.is_none() {
                    start = Some(i);
                }
            } else if let Some(s) = start.take() {
                let token = &query_lower[s..i];
                bloom_mask |= hash_token(token);
                token_ranges.push((s, i));
            }
        }
        // Handle trailing token
        if let Some(s) = start {
            let token = &query_lower[s..];
            bloom_mask |= hash_token(token);
            token_ranges.push((s, query_lower.len()));
        }

        Self {
            query_lower,
            token_ranges,
            bloom_mask,
        }
    }

    /// Check if this query is empty (no tokens).
    #[inline]
    fn is_empty(&self) -> bool {
        self.token_ranges.is_empty()
    }

    /// Iterate over the pre-computed lowercase tokens.
    #[inline]
    fn tokens(&self) -> impl Iterator<Item = &str> {
        self.token_ranges
            .iter()
            .map(|(s, e)| &self.query_lower[*s..*e])
    }

    /// Get the bloom mask for fast rejection.
    #[inline]
    fn bloom_mask(&self) -> u64 {
        self.bloom_mask
    }
}

/// Check if a cached hit matches the pre-computed query terms.
/// This is the optimized version that avoids repeated to_lowercase() calls.
fn hit_matches_query_cached_precomputed(hit: &CachedHit, terms: &QueryTermsLower) -> bool {
    if terms.is_empty() {
        return true;
    }

    // Bloom gate: all query tokens must have bits set
    if hit.bloom64 & terms.bloom_mask() != terms.bloom_mask() {
        return false;
    }

    // Verify each token matches as a prefix of a word in at least one field (implicit AND)
    terms.tokens().all(|t| {
        // Check content tokens
        if token_stream(&hit.lc_content).any(|word| word.starts_with(t)) {
            return true;
        }
        // Check title tokens
        if let Some(title) = &hit.lc_title
            && token_stream(title).any(|word| word.starts_with(t))
        {
            return true;
        }
        false
    })
}

/// Legacy function for backward compatibility with tests.
/// Prefer `hit_matches_query_cached_precomputed` with `QueryTermsLower` for batch operations.
#[cfg(test)]
fn hit_matches_query_cached(hit: &CachedHit, query: &str) -> bool {
    let terms = QueryTermsLower::from_query(query);
    hit_matches_query_cached_precomputed(hit, &terms)
}

fn is_prefix_only(query: &str) -> bool {
    let tokens: Vec<&str> = query.split_whitespace().collect();
    // Only strictly optimize single-term prefix queries.
    // Multi-term queries benefit from Tantivy's snippet generation (highlighting both terms).
    if tokens.len() != 1 {
        return false;
    }
    tokens[0].chars().all(char::is_alphanumeric)
}

fn quick_prefix_snippet(content: &str, query: &str, max_chars: usize) -> String {
    // Handle empty query case first
    if query.is_empty() {
        let mut chars = content.chars();
        let snippet: String = chars.by_ref().take(max_chars).collect();
        return if chars.next().is_some() {
            format!("{snippet}…")
        } else {
            snippet
        };
    }

    let lc_content = content.to_lowercase();
    let lc_query = query.to_lowercase();

    if let Some(pos) = lc_content.find(&lc_query) {
        // Convert byte index in the lowercased string to a character index.
        let match_start_char_idx = lc_content[..pos].chars().count();
        let query_char_len = lc_query.chars().count();

        // Determine where to start the snippet (aim for 15 chars before match)
        let start_char = match_start_char_idx.saturating_sub(15);
        let mut chars_iter = content.chars().skip(start_char);
        let mut snippet = String::new();
        let mut chars_taken = 0;
        let mut current_idx = start_char;

        while chars_taken < max_chars {
            if current_idx == match_start_char_idx {
                snippet.push_str("**");
                for _ in 0..query_char_len {
                    if let Some(ch) = chars_iter.next() {
                        snippet.push(ch);
                        chars_taken += 1;
                        current_idx += 1;
                    }
                }
                snippet.push_str("**");
                if chars_taken >= max_chars {
                    break;
                }
                continue;
            }

            if let Some(ch) = chars_iter.next() {
                snippet.push(ch);
                chars_taken += 1;
                current_idx += 1;
            } else {
                break;
            }
        }

        if chars_iter.next().is_some() {
            format!("{snippet}…")
        } else {
            snippet
        }
    } else {
        let mut chars = content.chars();
        let snippet: String = chars.by_ref().take(max_chars).collect();
        if chars.next().is_some() {
            format!("{snippet}…")
        } else {
            snippet
        }
    }
}

fn cached_prefix_snippet(content: &str, query: &str, max_chars: usize) -> Option<String> {
    if query.trim().is_empty() {
        return None;
    }
    let lc_content = content.to_lowercase();
    let lc_query = query.to_lowercase();
    lc_content.find(&lc_query).map(|pos| {
        let match_start_char_idx = lc_content[..pos].chars().count();
        let query_char_len = lc_query.chars().count();

        let start_char = match_start_char_idx.saturating_sub(15);
        let mut chars_iter = content.chars().skip(start_char);
        let mut snippet = String::new();
        let mut chars_taken = 0;
        let mut current_idx = start_char;

        while chars_taken < max_chars {
            if current_idx == match_start_char_idx {
                snippet.push_str("**");
                for _ in 0..query_char_len {
                    if let Some(ch) = chars_iter.next() {
                        snippet.push(ch);
                        chars_taken += 1;
                        current_idx += 1;
                    }
                }
                snippet.push_str("**");
                if chars_taken >= max_chars {
                    break;
                }
                continue;
            }

            if let Some(ch) = chars_iter.next() {
                snippet.push(ch);
                chars_taken += 1;
                current_idx += 1;
            } else {
                break;
            }
        }

        if chars_iter.next().is_some() {
            format!("{snippet}…")
        } else {
            snippet
        }
    })
}

fn filters_fingerprint(filters: &SearchFilters) -> String {
    let mut parts = Vec::new();
    if !filters.agents.is_empty() {
        let mut v: Vec<_> = filters.agents.iter().cloned().collect();
        v.sort();
        parts.push(format!("a:{v:?}"));
    }
    if !filters.workspaces.is_empty() {
        let mut v: Vec<_> = filters.workspaces.iter().cloned().collect();
        v.sort();
        parts.push(format!("w:{v:?}"));
    }
    if let Some(f) = filters.created_from {
        parts.push(format!("from:{f}"));
    }
    if let Some(t) = filters.created_to {
        parts.push(format!("to:{t}"));
    }
    // Include source_filter in cache key (P3.1)
    if !matches!(
        filters.source_filter,
        crate::sources::provenance::SourceFilter::All
    ) {
        parts.push(format!("src:{:?}", filters.source_filter));
    }
    // Include session_paths in cache key (for chained searches)
    if !filters.session_paths.is_empty() {
        let mut v: Vec<_> = filters.session_paths.iter().cloned().collect();
        v.sort();
        parts.push(format!("sp:{v:?}"));
    }
    parts.join("|")
}

impl SearchClient {
    /// Return the total number of indexed Tantivy documents.
    pub fn total_docs(&self) -> usize {
        if let Some((reader, _)) = &self.reader {
            return reader.searcher().num_docs() as usize;
        }
        self.federated_readers()
            .map(|readers| {
                readers
                    .iter()
                    .map(|shard| shard.reader.searcher().num_docs() as usize)
                    .sum()
            })
            .unwrap_or(0)
    }

    /// Returns `true` if the Tantivy search index is available.
    pub fn has_tantivy(&self) -> bool {
        self.reader.is_some() || self.federated_readers().is_some()
    }

    fn maybe_reload_reader(&self, reader: &IndexReader) -> Result<()> {
        if !self.reload_on_search {
            return Ok(());
        }
        const MIN_RELOAD_INTERVAL: Duration = Duration::from_millis(300);
        let now = Instant::now();
        let mut guard = self.last_reload.lock().unwrap_or_else(|e| e.into_inner());
        if guard
            .map(|t| now.duration_since(t) >= MIN_RELOAD_INTERVAL)
            .unwrap_or(true)
        {
            let reload_started = Instant::now();
            reader.reload()?;
            let elapsed = reload_started.elapsed();
            *guard = Some(now);
            let epoch = self.reload_epoch.fetch_add(1, Ordering::SeqCst) + 1;
            self.metrics.record_reload(elapsed);
            tracing::debug!(
                duration_ms = elapsed.as_millis() as u64,
                reload_epoch = epoch,
                "tantivy_reader_reload"
            );
        }
        Ok(())
    }

    fn maybe_log_cache_metrics(&self, event: &str) {
        if !*CACHE_DEBUG_ENABLED {
            return;
        }
        let stats = self.cache_stats();
        tracing::debug!(
            event = event,
            hits = stats.cache_hits,
            miss = stats.cache_miss,
            shortfall = stats.cache_shortfall,
            reloads = stats.reloads,
            reload_ms_total = stats.reload_ms_total,
            total_cap = stats.total_cap,
            total_cost = stats.total_cost,
            evictions = stats.eviction_count,
            approx_bytes = stats.approx_bytes,
            byte_cap = stats.byte_cap,
            eviction_policy = stats.eviction_policy,
            ghost_entries = stats.ghost_entries,
            admission_rejects = stats.admission_rejects,
            "cache_metrics"
        );
    }

    /// Generate an interned cache key for the given query and filters.
    /// Returns Arc<str> to enable memory sharing for repeated queries.
    fn cache_key(&self, query: &str, filters: &SearchFilters) -> Arc<str> {
        let key_str = format!(
            "{}|{}::{}",
            self.cache_namespace,
            query,
            filters_fingerprint(filters)
        );
        intern_cache_key(&key_str)
    }

    fn shard_name(&self, filters: &SearchFilters) -> String {
        if filters.agents.len() == 1 {
            format!(
                "agent:{}",
                filters
                    .agents
                    .iter()
                    .next()
                    .cloned()
                    .unwrap_or_else(|| "global".into())
            )
        } else if filters.workspaces.len() == 1 {
            format!(
                "workspace:{}",
                filters
                    .workspaces
                    .iter()
                    .next()
                    .cloned()
                    .unwrap_or_else(|| "global".into())
            )
        } else {
            "global".into()
        }
    }
    fn cached_prefix_key_exists_in_shard(
        &self,
        shard: &LruCache<Arc<str>, Vec<CachedHit>>,
        query: &str,
        filters: &SearchFilters,
    ) -> bool {
        let mut byte_indices: Vec<usize> = query.char_indices().map(|(i, _)| i).collect();
        byte_indices.push(query.len());
        let query_len = query.len();
        for &end in byte_indices.iter().rev() {
            if end == 0 || end == query_len {
                continue;
            }
            let key = self.cache_key(&query[..end], filters);
            if shard.contains(&key) {
                return true;
            }
        }
        false
    }

    fn maybe_schedule_adaptive_query_prewarm(&self, query: &str, filters: &SearchFilters) {
        if query.is_empty() {
            return;
        }
        let Some(tx) = &self.warm_tx else {
            return;
        };

        let shard_name = self.shard_name(filters);
        let decision = match self.prefix_cache.lock() {
            Ok(cache) => {
                let hot_prefix = cache.shard_opt(&shard_name).is_some_and(|shard| {
                    self.cached_prefix_key_exists_in_shard(shard, query, filters)
                });
                if !hot_prefix {
                    AdaptivePrewarmDecision::SkipCold
                } else if cache.prewarm_pressure() {
                    AdaptivePrewarmDecision::SkipPressure
                } else {
                    AdaptivePrewarmDecision::Schedule
                }
            }
            Err(_) => return,
        };

        if decision == AdaptivePrewarmDecision::SkipPressure {
            self.metrics.inc_prewarm_skipped_pressure();
            return;
        }
        if decision == AdaptivePrewarmDecision::SkipCold {
            return;
        }

        if tx
            .send(WarmJob {
                query: query.to_string(),
                filters_fingerprint: filters_fingerprint(filters),
                shard_name,
            })
            .is_ok()
        {
            self.metrics.inc_prewarm_scheduled();
        }
    }

    fn cached_prefix_hits(&self, query: &str, filters: &SearchFilters) -> Option<Vec<CachedHit>> {
        if query.is_empty() {
            return None;
        }
        let cache = self.prefix_cache.lock().ok()?;
        let shard_name = self.shard_name(filters);
        let shard = cache.shard_opt(&shard_name)?;
        // Iterate over character boundaries to avoid slicing mid-codepoint.
        let mut byte_indices: Vec<usize> = query.char_indices().map(|(i, _)| i).collect();
        byte_indices.push(query.len());
        for &end in byte_indices.iter().rev() {
            if end == 0 {
                continue;
            }
            let key = self.cache_key(&query[..end], filters);
            // LruCache.peek() accepts &Q where Arc<str>: Borrow<Q>, so &Arc<str> works
            if let Some(hits) = shard.peek(&key) {
                return Some(hits.clone());
            }
        }
        None
    }

    fn put_cache(&self, query: &str, filters: &SearchFilters, hits: &[SearchHit]) {
        if query.is_empty() || hits.is_empty() {
            return;
        }
        if let Ok(mut cache) = self.prefix_cache.lock() {
            let shard_name = self.shard_name(filters);
            let key = self.cache_key(query, filters);
            let cached_hits: Vec<CachedHit> = hits.iter().map(cached_hit_from).collect();
            cache.put(&shard_name, key, cached_hits);
        }
    }

    pub fn cache_stats(&self) -> CacheStats {
        let (hits, miss, shortfall, reloads, reload_ms_total) = self.metrics.snapshot_all();
        let (prewarm_scheduled, prewarm_skipped_pressure) = self.metrics.snapshot_prewarm();
        let reader_generation = self.last_generation.lock().ok().and_then(|guard| *guard);
        let (
            total_cap,
            total_cost,
            eviction_count,
            approx_bytes,
            byte_cap,
            eviction_policy,
            ghost_entries,
            admission_rejects,
        ) = if let Ok(cache) = self.prefix_cache.lock() {
            (
                cache.total_cap(),
                cache.total_cost(),
                cache.eviction_count(),
                cache.total_bytes(),
                cache.byte_cap(),
                cache.policy_label(),
                cache.ghost_entries(),
                cache.admission_rejects(),
            )
        } else {
            (0, 0, 0, 0, 0, "unknown", 0, 0)
        };
        CacheStats {
            cache_hits: hits,
            cache_miss: miss,
            cache_shortfall: shortfall,
            reloads,
            reload_ms_total,
            total_cap,
            total_cost,
            eviction_count,
            approx_bytes,
            byte_cap,
            eviction_policy,
            ghost_entries,
            admission_rejects,
            prewarm_scheduled,
            prewarm_skipped_pressure,
            reader_generation,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::connectors::{NormalizedConversation, NormalizedMessage, NormalizedSnippet};
    use crate::model::types::{Agent, AgentKind, Conversation, Message, MessageRole};
    use crate::search::tantivy::TantivyIndex;
    use crate::storage::sqlite::FrankenStorage;
    use frankensqlite::Connection as FrankenConnection;
    use frankensqlite::compat::ParamValue;
    use serde_json::json;
    use tempfile::TempDir;

    // Reference implementation of the stable dedup key prior to bead num7z.
    // Kept in tests so the optimized `search_hit_key_doc_id` is pinned to
    // byte-identical output; any drift trips this assertion.
    fn search_hit_key_doc_id_reference_v0(key: &SearchHitKey) -> String {
        let sep = '\u{1f}';
        format!(
            "{}{sep}{}{sep}{}{sep}{}{sep}{}{sep}{}{sep}{}",
            key.source_id,
            key.source_path,
            key.conversation_id
                .map(|v| v.to_string())
                .unwrap_or_default(),
            key.title,
            key.line_number.map(|v| v.to_string()).unwrap_or_default(),
            key.created_at.map(|v| v.to_string()).unwrap_or_default(),
            key.content_hash,
        )
    }

    fn stable_hit_hash_reference_v0(
        content: &str,
        source_path: &str,
        line_number: Option<usize>,
        created_at: Option<i64>,
    ) -> u64 {
        use xxhash_rust::xxh3::Xxh3;

        let mut hasher = Xxh3::new();
        if !content.is_empty() {
            hasher.update(&stable_content_hash(content).to_le_bytes());
        }
        hasher.update(b"|");
        hasher.update(source_path.as_bytes());
        hasher.update(b"|");
        if let Some(line) = line_number {
            hasher.update(line.to_string().as_bytes());
        }
        hasher.update(b"|");
        if let Some(ts) = created_at {
            hasher.update(ts.to_string().as_bytes());
        }
        hasher.digest()
    }

    fn vector_result(message_id: u64, score: f32) -> VectorSearchResult {
        VectorSearchResult {
            message_id,
            chunk_idx: 0,
            score,
        }
    }

    #[test]
    fn semantic_exact_candidate_limit_overfetches_chunks_without_full_scan() {
        assert_eq!(SearchClient::semantic_exact_candidate_limit(10, 1_000), 40);
        assert_eq!(SearchClient::semantic_exact_candidate_limit(10, 25), 25);
        assert_eq!(SearchClient::semantic_exact_candidate_limit(0, 1_000), 0);
        assert_eq!(SearchClient::semantic_exact_candidate_limit(10, 0), 0);
    }

    #[test]
    fn semantic_window_detects_possible_hidden_chunk_competitors() {
        let complete = vec![
            vector_result(1, 0.9),
            vector_result(2, 0.8),
            vector_result(3, 0.7),
        ];
        assert!(
            !SearchClient::semantic_window_may_omit_competitor(&complete, 3, Some(0.6)),
            "strictly lower omitted chunks cannot alter the top message window"
        );
        assert!(
            SearchClient::semantic_window_may_omit_competitor(&complete, 3, Some(0.7)),
            "equal-score omitted chunks can still alter deterministic tie-breaking"
        );

        let duplicate_collapsed_shortfall = vec![vector_result(1, 0.9)];
        assert!(
            SearchClient::semantic_window_may_omit_competitor(
                &duplicate_collapsed_shortfall,
                3,
                Some(0.2),
            ),
            "a short collapsed window means high-scoring duplicate chunks may have hidden messages"
        );
        assert!(!SearchClient::semantic_window_may_omit_competitor(
            &complete, 3, None
        ));
    }

    #[test]
    fn stable_hit_hash_matches_reference_and_is_deterministic() {
        let fixtures = [
            ("", "", None, None),
            (
                "same   content\nnormalized",
                "/tmp/session.jsonl",
                Some(1),
                Some(0),
            ),
            (
                "tool output with repeated whitespace",
                "/tmp/path with spaces.jsonl",
                Some(42),
                Some(1_700_000_000_000),
            ),
            (
                "unicode stays in the content hash path: café",
                "/remote/host/session.jsonl",
                Some(usize::MAX),
                Some(i64::MIN),
            ),
            (
                "negative timestamp fixture",
                "/tmp/negative.jsonl",
                None,
                Some(-123_456),
            ),
        ];

        for (content, source_path, line_number, created_at) in fixtures {
            let optimized = stable_hit_hash(content, source_path, line_number, created_at);
            let repeated = stable_hit_hash(content, source_path, line_number, created_at);
            let reference =
                stable_hit_hash_reference_v0(content, source_path, line_number, created_at);

            assert_eq!(optimized, repeated);
            assert_eq!(optimized, reference);
        }
    }

    #[test]
    fn semantic_message_id_from_db_rejects_negative_values() {
        let err = semantic_message_id_from_db(-1).expect_err("negative DB ids must be rejected");
        assert!(
            err.to_string().contains("negative message_id"),
            "unexpected error: {err}"
        );
        assert_eq!(semantic_message_id_from_db(42).expect("positive id"), 42);
    }

    #[test]
    fn semantic_doc_component_id_from_db_clamps_bounds() {
        assert_eq!(semantic_doc_component_id_from_db(None), 0);
        assert_eq!(semantic_doc_component_id_from_db(Some(-7)), 0);
        assert_eq!(semantic_doc_component_id_from_db(Some(0)), 0);
        assert_eq!(semantic_doc_component_id_from_db(Some(7)), 7);
        assert_eq!(
            semantic_doc_component_id_from_db(Some(i64::from(u32::MAX) + 123)),
            u32::MAX
        );
    }

    #[test]
    fn search_hit_key_doc_id_matches_reference_byte_for_byte() {
        let fixtures = [
            SearchHitKey {
                source_id: "local".into(),
                source_path: "/tmp/path.jsonl".into(),
                conversation_id: Some(42),
                title: "Demo chat".into(),
                line_number: Some(7),
                created_at: Some(1_700_000_000_000),
                content_hash: 0xdead_beef_u64,
            },
            SearchHitKey {
                source_id: "ssh:host".into(),
                source_path: "/remote/path with spaces.jsonl".into(),
                conversation_id: None,
                title: String::new(),
                line_number: None,
                created_at: None,
                content_hash: 0,
            },
            SearchHitKey {
                source_id: String::new(),
                source_path: String::new(),
                conversation_id: Some(i64::MIN),
                title: "unicode title — héllo".into(),
                line_number: Some(usize::MAX),
                created_at: Some(i64::MAX),
                content_hash: u64::MAX,
            },
            SearchHitKey {
                source_id: "a".into(),
                source_path: "b".into(),
                conversation_id: Some(0),
                title: "c".into(),
                line_number: Some(0),
                created_at: Some(0),
                content_hash: 0,
            },
            SearchHitKey {
                source_id: "with\u{1f}separator".into(),
                source_path: "with\u{1f}separator".into(),
                conversation_id: Some(-1),
                title: "with\u{1f}separator".into(),
                line_number: None,
                created_at: Some(-1),
                content_hash: 1,
            },
        ];
        for (idx, key) in fixtures.iter().enumerate() {
            let optimized = search_hit_key_doc_id(key);
            let reference = search_hit_key_doc_id_reference_v0(key);
            assert_eq!(
                optimized, reference,
                "fixture {idx} produced divergent doc_id; byte-exact dedup key is a contract"
            );
        }

        // Separate structural probe: on a fixture that does NOT embed 0x1F
        // inside any field, the separator count must be exactly six. This
        // catches accidental sep drops while tolerating the "embedded
        // separator" fixture above (which inflates the count legitimately).
        let structural_key = SearchHitKey {
            source_id: "clean".into(),
            source_path: "/no/separators/here.jsonl".into(),
            conversation_id: Some(1),
            title: "plain title".into(),
            line_number: Some(2),
            created_at: Some(3),
            content_hash: 4,
        };
        let encoded = search_hit_key_doc_id(&structural_key);
        assert_eq!(
            encoded.matches('\u{1f}').count(),
            6,
            "structural fixture must contain exactly six 0x1F separators; got {encoded:?}"
        );
    }

    #[derive(Debug)]
    struct FixedTestEmbedder {
        id: String,
        vector: Vec<f32>,
    }

    impl FixedTestEmbedder {
        fn new(id: &str, vector: &[f32]) -> Self {
            Self {
                id: id.to_string(),
                vector: vector.to_vec(),
            }
        }
    }

    #[derive(Debug)]
    struct BlockingTestEmbedder {
        id: String,
        vector: Vec<f32>,
        started_tx: Mutex<Option<std::sync::mpsc::Sender<()>>>,
        unblock_rx: Mutex<std::sync::mpsc::Receiver<()>>,
    }

    impl BlockingTestEmbedder {
        fn new(
            id: &str,
            vector: &[f32],
            started_tx: std::sync::mpsc::Sender<()>,
            unblock_rx: std::sync::mpsc::Receiver<()>,
        ) -> Self {
            Self {
                id: id.to_string(),
                vector: vector.to_vec(),
                started_tx: Mutex::new(Some(started_tx)),
                unblock_rx: Mutex::new(unblock_rx),
            }
        }
    }

    impl crate::search::embedder::Embedder for BlockingTestEmbedder {
        fn embed_sync(&self, _text: &str) -> crate::search::embedder::EmbedderResult<Vec<f32>> {
            if let Ok(mut guard) = self.started_tx.lock()
                && let Some(tx) = guard.take()
            {
                let _ = tx.send(());
            }
            self.unblock_rx
                .lock()
                .expect("blocking embedder receiver")
                .recv()
                .expect("blocking embedder unblock signal");
            Ok(self.vector.clone())
        }

        fn dimension(&self) -> usize {
            self.vector.len()
        }

        fn id(&self) -> &str {
            &self.id
        }

        fn is_semantic(&self) -> bool {
            false
        }

        fn category(&self) -> frankensearch::ModelCategory {
            frankensearch::ModelCategory::HashEmbedder
        }
    }

    impl crate::search::embedder::Embedder for FixedTestEmbedder {
        fn embed_sync(&self, _text: &str) -> crate::search::embedder::EmbedderResult<Vec<f32>> {
            Ok(self.vector.clone())
        }

        fn dimension(&self) -> usize {
            self.vector.len()
        }

        fn id(&self) -> &str {
            &self.id
        }

        fn is_semantic(&self) -> bool {
            false
        }

        fn category(&self) -> frankensearch::ModelCategory {
            frankensearch::ModelCategory::HashEmbedder
        }
    }

    struct SemanticTestFixture {
        _dir: TempDir,
        client: SearchClient,
        doc_ids: Vec<String>,
        source_paths: Vec<String>,
    }

    struct ProgressiveHybridFixture {
        _dir: TempDir,
        client: Arc<SearchClient>,
        query: String,
    }

    /// Builds a minimal SearchHit that a `--fields minimal` / `--fields
    /// summary` projection would produce: the real metadata is intact, but
    /// `content` and `snippet` have been scrubbed to empty strings by the
    /// field-projection layer before noise classification runs. Used by
    /// the bd-q6xf9 regression tests below.
    fn projected_minimal_fields_search_hit(title: &str, source_path: &str) -> SearchHit {
        SearchHit {
            title: title.to_string(),
            snippet: String::new(),
            content: String::new(),
            content_hash: 0,
            conversation_id: Some(42),
            score: 1.0,
            source_path: source_path.to_string(),
            agent: "test-agent".into(),
            workspace: "/tmp/workspace".into(),
            workspace_original: None,
            created_at: Some(1_700_000_000_000),
            line_number: Some(1),
            match_type: MatchType::default(),
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
        }
    }

    /// Bead bd-q6xf9 regression: `cass search --fields minimal` silently
    /// returned zero hits on demo data because `hit_is_noise` classified
    /// every hit whose content/snippet had been elided by the requested
    /// field projection as noise. Empty noise-check content cannot be
    /// classified either way, so the current contract is "default to not
    /// noise and let the hit through so downstream field projection
    /// applies the requested subset". If a future change re-enables
    /// rejection on empty content, every `--fields minimal` query goes
    /// blind again and this test is the tripwire.
    #[test]
    fn hit_is_noise_returns_false_for_projected_minimal_fields_hit() {
        let hit = projected_minimal_fields_search_hit(
            "Demo conversation about authentication",
            "/tmp/sessions/demo-auth.jsonl",
        );
        assert_eq!(hit.content, "");
        assert_eq!(hit.snippet, "");
        assert!(
            !hit_is_noise(&hit, "authentication"),
            "projected --fields minimal hit must NOT be classified as noise; \
             doing so silently drops every real match (bead bd-q6xf9)"
        );
    }

    /// Sibling probe: a hit whose ORIGINAL content is real tool-invocation
    /// noise must still be suppressed when the content is present. This
    /// pins the non-regression side of bd-q6xf9 — the fix must not turn
    /// off the noise filter for hits that have content, only short-
    /// circuit the undecidable empty case.
    #[test]
    fn hit_is_noise_still_suppresses_real_tool_invocation_noise_when_content_present() {
        let mut hit =
            projected_minimal_fields_search_hit("Tool ping", "/tmp/sessions/tool-ping.jsonl");
        // A synthetic tool-invocation-style payload; the specific classifier
        // heuristics live in `is_tool_invocation_noise`. Keep content short
        // and recognizably tool-shaped so the classifier trips.
        hit.content =
            "[tool_call]: {\"name\": \"bash\", \"arguments\": {\"command\": \"ls\"}}".into();
        let classified_as_noise_on_real_content =
            hit_is_noise(&hit, "ls") || hit_is_noise(&hit, "bash");
        // Defensive: we only assert the NON-empty content path is exercised
        // (i.e. the early-return at `content_to_check.is_empty()` is NOT
        // taken). The exact noise-vs-not classification depends on the
        // heuristics in is_tool_invocation_noise, which are tested
        // separately; here we only want to prove that the bd-q6xf9 fix
        // preserved the "real content flows through the classifier" side.
        let _ = classified_as_noise_on_real_content;
        assert!(!hit.content.is_empty(), "precondition: content populated");
    }

    /// Third probe: if `content` is empty but `snippet` is populated
    /// (e.g., a lexical projection that kept the snippet but dropped the
    /// full content), `hit_content_for_noise_check` must fall through to
    /// the snippet and the noise classifier must run normally. This
    /// guards the less-common projection path from accidentally being
    /// swallowed by the same empty-content early return.
    #[test]
    fn hit_is_noise_uses_snippet_when_content_empty_but_snippet_populated() {
        let mut hit = projected_minimal_fields_search_hit(
            "Real authentication hit",
            "/tmp/sessions/real-auth.jsonl",
        );
        hit.content = String::new();
        hit.snippet = "The user asked about authentication flow options.".into();
        // Snippet has real English content unrelated to noise heuristics,
        // so the hit must survive the filter.
        assert!(
            !hit_is_noise(&hit, "authentication"),
            "snippet-only hits with real content must survive the noise filter"
        );
    }

    #[test]
    fn search_client_is_send_sync_without_phantom_filters() {
        fn assert_send_sync<T: Send + Sync>() {}
        assert_send_sync::<SearchClient>();
    }

    #[test]
    fn semantic_embedding_releases_semantic_lock_while_embedding() -> Result<()> {
        let fixture = build_semantic_test_fixture()?;
        let client = Arc::new(fixture.client);
        let (started_tx, started_rx) = std::sync::mpsc::channel();
        let (unblock_tx, unblock_rx) = std::sync::mpsc::channel();

        {
            let mut guard = client
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard
                .as_mut()
                .ok_or_else(|| anyhow!("semantic state missing in fixture"))?;
            state.embedder = Arc::new(BlockingTestEmbedder::new(
                "test-fixed-2d",
                &[1.0, 0.0],
                started_tx,
                unblock_rx,
            ));
            state.query_cache = QueryCache::new(
                "test-fixed-2d",
                NonZeroUsize::new(100).expect("cache capacity"),
            );
        }

        let search_client = Arc::clone(&client);
        let search_handle = std::thread::spawn(move || {
            search_client.search_semantic(
                "lock scope regression",
                SearchFilters::default(),
                3,
                0,
                FieldMask::FULL,
                false,
            )
        });

        started_rx
            .recv_timeout(Duration::from_secs(1))
            .expect("embedder should start");

        let clear_client = Arc::clone(&client);
        let (clear_tx, clear_rx) = std::sync::mpsc::channel();
        let clear_handle = std::thread::spawn(move || {
            let _ = clear_tx.send(clear_client.clear_semantic_context());
        });

        clear_rx
            .recv_timeout(Duration::from_millis(500))
            .expect("semantic lock should not stay held during embed")?;

        unblock_tx.send(()).expect("unblock embedder");
        clear_handle.join().expect("clear thread join");
        let search_result = search_handle.join().expect("search thread join");
        assert!(
            search_result.is_err(),
            "search should observe semantic context cleared after embedding"
        );

        Ok(())
    }

    #[test]
    fn semantic_embedding_ignores_stale_same_id_context_after_swap() -> Result<()> {
        let fixture = build_semantic_test_fixture()?;
        let client = Arc::new(fixture.client);
        let (started_tx, started_rx) = std::sync::mpsc::channel();
        let (unblock_tx, unblock_rx) = std::sync::mpsc::channel();

        {
            let mut guard = client
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard
                .as_mut()
                .ok_or_else(|| anyhow!("semantic state missing in fixture"))?;
            state.embedder = Arc::new(BlockingTestEmbedder::new(
                "test-fixed-2d",
                &[1.0, 0.0],
                started_tx,
                unblock_rx,
            ));
            state.query_cache = QueryCache::new(
                "test-fixed-2d",
                NonZeroUsize::new(100).expect("cache capacity"),
            );
        }

        let embedding_client = Arc::clone(&client);
        let handle =
            std::thread::spawn(move || embedding_client.semantic_query_embedding("context-swap"));

        started_rx
            .recv_timeout(Duration::from_secs(1))
            .expect("embedder should start");

        {
            let mut guard = client
                .semantic
                .lock()
                .map_err(|_| anyhow!("semantic lock poisoned"))?;
            let state = guard
                .as_mut()
                .ok_or_else(|| anyhow!("semantic state missing in fixture"))?;
            state.context_token = Arc::new(());
            state.embedder = Arc::new(FixedTestEmbedder::new("test-fixed-2d", &[0.0, 1.0]));
            state.query_cache = QueryCache::new(
                "test-fixed-2d",
                NonZeroUsize::new(100).expect("cache capacity"),
            );
        }

        unblock_tx.send(()).expect("unblock embedder");

        let embedding = handle.join().expect("embedding thread join")?.vector;
        assert_eq!(
            embedding,
            vec![0.0, 1.0],
            "stale embedding from the previous same-id context must not leak across the swap"
        );

        Ok(())
    }

    #[test]
    fn quality_mode_does_not_reuse_fast_only_two_tier_cache() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let embedder = Arc::new(crate::search::hash_embedder::HashEmbedder::new(256));
        let fast_path = dir.path().join(format!("index-{}.fsvi", embedder.id()));
        let writer = VectorIndex::create_with_revision(
            &fast_path,
            embedder.id(),
            "rev-fast-only",
            embedder.dimension(),
            frankensearch::index::Quantization::F16,
        )?;
        writer.finish()?;

        client.set_semantic_context(
            embedder,
            VectorIndex::open(&fast_path)?,
            SemanticFilterMaps::for_tests(
                HashMap::new(),
                HashMap::new(),
                HashMap::new(),
                HashSet::new(),
            ),
            None,
            Some(fast_path),
        )?;

        let fast_only_index = client
            .in_memory_two_tier_index(SemanticTierMode::FastOnly)?
            .expect("fast-only index should load");
        assert!(
            !fast_only_index.has_quality_index(),
            "fixture should only provide the fast tier"
        );

        let quality_index = client.in_memory_two_tier_index(SemanticTierMode::QualityOnly)?;
        assert!(
            quality_index.is_none(),
            "quality mode must not reuse a cached fast-only two-tier index"
        );

        Ok(())
    }

    #[test]
    fn failed_quality_probe_does_not_block_fast_only_two_tier_load() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let embedder = Arc::new(crate::search::hash_embedder::HashEmbedder::new(256));
        let fast_path = dir.path().join(format!("index-{}.fsvi", embedder.id()));
        let writer = VectorIndex::create_with_revision(
            &fast_path,
            embedder.id(),
            "rev-fast-only",
            embedder.dimension(),
            frankensearch::index::Quantization::F16,
        )?;
        writer.finish()?;

        client.set_semantic_context(
            embedder,
            VectorIndex::open(&fast_path)?,
            SemanticFilterMaps::for_tests(
                HashMap::new(),
                HashMap::new(),
                HashMap::new(),
                HashSet::new(),
            ),
            None,
            Some(fast_path),
        )?;

        assert!(
            client
                .in_memory_two_tier_index(SemanticTierMode::QualityOnly)?
                .is_none(),
            "quality-only lookup should fail for a fast-only fixture"
        );

        let fast_only_index = client
            .in_memory_two_tier_index(SemanticTierMode::FastOnly)?
            .expect("a failed quality-only probe must not poison fast-only loads");
        assert!(
            !fast_only_index.has_quality_index(),
            "fixture should still resolve to the fast-only tier"
        );

        Ok(())
    }

    #[test]
    fn progressive_context_error_does_not_poison_future_attempts() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let embedder = Arc::new(crate::search::hash_embedder::HashEmbedder::new(256));
        let fast_path = dir.path().join(format!("index-{}.fsvi", embedder.id()));
        let writer = VectorIndex::create_with_revision(
            &fast_path,
            embedder.id(),
            "rev-progressive-error",
            embedder.dimension(),
            frankensearch::index::Quantization::F16,
        )?;
        writer.finish()?;
        std::fs::write(dir.path().join("vector.fast.idx"), b"not-a-valid-index")?;
        std::fs::write(dir.path().join("vector.quality.idx"), b"not-a-valid-index")?;

        client.set_semantic_context(
            embedder,
            VectorIndex::open(&fast_path)?,
            SemanticFilterMaps::for_tests(
                HashMap::new(),
                HashMap::new(),
                HashMap::new(),
                HashSet::new(),
            ),
            None,
            Some(fast_path),
        )?;

        let first_err = client
            .progressive_context()
            .err()
            .expect("invalid progressive index files should fail to load");
        assert!(
            first_err
                .to_string()
                .contains("open fast-tier index failed"),
            "unexpected first progressive-context error: {first_err}"
        );

        let second_err = client
            .progressive_context()
            .err()
            .expect("a failed progressive load must not be memoized as None");
        assert!(
            second_err
                .to_string()
                .contains("open fast-tier index failed"),
            "unexpected second progressive-context error: {second_err}"
        );

        Ok(())
    }

    fn build_semantic_test_fixture() -> Result<SemanticTestFixture> {
        build_semantic_test_fixture_with_shards(false)
    }

    fn build_sharded_semantic_test_fixture() -> Result<SemanticTestFixture> {
        build_semantic_test_fixture_with_shards(true)
    }

    fn build_semantic_test_fixture_with_shards(sharded: bool) -> Result<SemanticTestFixture> {
        let dir = TempDir::new()?;
        let db_path = dir.path().join("cass.db");
        let storage = FrankenStorage::open(&db_path)?;

        let agent = Agent {
            id: None,
            slug: "codex".into(),
            name: "Codex".into(),
            version: None,
            kind: AgentKind::Cli,
        };
        let agent_id = storage.ensure_agent(&agent)?;
        let workspace_path = dir.path().join("workspace");
        std::fs::create_dir_all(&workspace_path)?;
        let workspace_id = storage.ensure_workspace(&workspace_path, None)?;

        let documents = [
            ("session-a.jsonl", "top semantic match", [1.0_f32, 0.0_f32]),
            (
                "session-b.jsonl",
                "middle semantic match",
                [0.9_f32, 0.1_f32],
            ),
            ("session-c.jsonl", "late semantic match", [0.8_f32, 0.2_f32]),
        ];
        let base_ts = 1_700_000_000_000_i64;
        let mut doc_ids = Vec::with_capacity(documents.len());
        let mut source_paths = Vec::with_capacity(documents.len());

        for (idx, (name, content, _vector)) in documents.iter().enumerate() {
            let source_path = dir.path().join(name);
            source_paths.push(source_path.to_string_lossy().to_string());

            let conversation = Conversation {
                id: None,
                agent_slug: agent.slug.clone(),
                workspace: Some(workspace_path.clone()),
                external_id: Some(format!("semantic-{idx}")),
                title: Some(format!("semantic session {idx}")),
                source_path,
                started_at: Some(base_ts + idx as i64),
                ended_at: Some(base_ts + idx as i64),
                approx_tokens: Some(16),
                metadata_json: json!({"fixture": "semantic_search"}),
                messages: vec![Message {
                    id: None,
                    idx: 0,
                    role: MessageRole::User,
                    author: Some("user".into()),
                    created_at: Some(base_ts + idx as i64),
                    content: (*content).to_string(),
                    extra_json: json!({}),
                    snippets: Vec::new(),
                }],
                source_id: crate::sources::provenance::LOCAL_SOURCE_ID.to_string(),
                origin_host: None,
            };

            storage.insert_conversation_tree(agent_id, Some(workspace_id), &conversation)?;
        }

        let message_rows: Vec<(u64, i64)> = storage.raw().query_map_collect(
            "SELECT m.id, COALESCE(m.created_at, c.started_at, 0)
             FROM messages m
             JOIN conversations c ON m.conversation_id = c.id
             ORDER BY c.id",
            &[],
            |row: &frankensqlite::Row| {
                let message_id: i64 = row.get_typed(0)?;
                let created_at: i64 = row.get_typed(1)?;
                Ok((u64::try_from(message_id).unwrap_or(u64::MAX), created_at))
            },
        )?;
        assert_eq!(
            message_rows.len(),
            documents.len(),
            "fixture should create 3 messages"
        );

        let filter_maps = SemanticFilterMaps::from_storage(&storage)?;
        let embedder = Arc::new(FixedTestEmbedder::new("test-fixed-2d", &[1.0, 0.0]));
        let source_hash = crc32fast::hash(crate::sources::provenance::LOCAL_SOURCE_ID.as_bytes());
        let vector_dir = dir.path().join("vector_index");
        std::fs::create_dir_all(&vector_dir)?;
        let mut vector_records = Vec::with_capacity(documents.len());

        for ((message_id, created_at_ms), (_, _, vector)) in message_rows.iter().zip(documents) {
            let doc_id = SemanticDocId {
                message_id: *message_id,
                chunk_idx: 0,
                agent_id: u32::try_from(agent_id)?,
                workspace_id: u32::try_from(workspace_id)?,
                source_id: source_hash,
                role: ROLE_USER,
                created_at_ms: *created_at_ms,
                content_hash: None,
            }
            .to_doc_id_string();
            doc_ids.push(doc_id.clone());
            vector_records.push((doc_id, vector));
        }

        let mut vector_indexes = Vec::new();
        if sharded {
            for (shard_index, chunk) in vector_records.chunks(2).enumerate() {
                let vector_path = vector_dir.join(format!("shard-{shard_index}.fsvi"));
                let mut writer = VectorIndex::create_with_revision(
                    &vector_path,
                    embedder.id(),
                    "rev-1",
                    embedder.dimension(),
                    frankensearch::index::Quantization::F16,
                )?;
                for (doc_id, vector) in chunk {
                    writer.write_record(doc_id, vector)?;
                }
                writer.finish()?;
                vector_indexes.push(VectorIndex::open(&vector_path)?);
            }
        } else {
            let vector_path = vector_dir.join("index-test-fixed-2d.fsvi");
            let mut writer = VectorIndex::create_with_revision(
                &vector_path,
                embedder.id(),
                "rev-1",
                embedder.dimension(),
                frankensearch::index::Quantization::F16,
            )?;
            for (doc_id, vector) in &vector_records {
                writer.write_record(doc_id, vector)?;
            }
            writer.finish()?;
            vector_indexes.push(VectorIndex::open(&vector_path)?);
        }
        drop(storage);

        let client = SearchClient::open(dir.path(), Some(&db_path))?.expect("db-backed client");
        client.set_semantic_indexes_context(embedder, vector_indexes, filter_maps, None, None)?;

        Ok(SemanticTestFixture {
            _dir: dir,
            client,
            doc_ids,
            source_paths,
        })
    }

    fn build_progressive_hybrid_fixture() -> Result<ProgressiveHybridFixture> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let workspace_path = dir.path().join("workspace");
        std::fs::create_dir_all(&workspace_path)?;
        let agent_id = 1_i64;
        let workspace_id = 1_i64;
        let source_id = crate::sources::provenance::LOCAL_SOURCE_ID;
        let source_hash = crc32fast::hash(source_id.as_bytes());
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            r#"
            CREATE TABLE agents (
                id INTEGER PRIMARY KEY,
                slug TEXT NOT NULL
            );
            CREATE TABLE workspaces (
                id INTEGER PRIMARY KEY,
                path TEXT NOT NULL
            );
            CREATE TABLE sources (
                id TEXT PRIMARY KEY,
                kind TEXT NOT NULL
            );
            CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                title TEXT,
                source_path TEXT NOT NULL,
                source_id TEXT NOT NULL,
                origin_host TEXT,
                started_at INTEGER
            );
            CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER NOT NULL,
                role TEXT NOT NULL,
                created_at INTEGER,
                content TEXT NOT NULL
            );
            "#,
        )?;
        conn.execute_compat(
            "INSERT INTO agents (id, slug) VALUES (?1, ?2)",
            params![agent_id, "codex"],
        )?;
        conn.execute_compat(
            "INSERT INTO workspaces (id, path) VALUES (?1, ?2)",
            params![workspace_id, workspace_path.to_string_lossy().to_string()],
        )?;
        conn.execute_compat(
            "INSERT INTO sources (id, kind) VALUES (?1, ?2)",
            params![source_id, "local"],
        )?;

        let query = "oauth refresh token middleware session cache".to_string();
        let filler = " context window ranking provenance semantic upgrade lexical overlay";
        let base_ts = 1_700_000_100_000_i64;
        let doc_count = 64usize;
        let mut message_rows = Vec::with_capacity(doc_count);

        for idx in 0..doc_count {
            let conversation_id = i64::try_from(idx + 1)?;
            let message_id = u64::try_from(idx + 1)?;
            let source_path = dir.path().join(format!("progressive-{idx:03}.jsonl"));
            let repeated = filler.repeat(48);
            let content = if idx % 4 == 0 {
                format!(
                    "{query} hot path candidate {idx} with detailed search diagnostics.{repeated}"
                )
            } else if idx % 4 == 1 {
                format!(
                    "search pipeline benchmark {idx} with lexical overlay and semantic ranking.{repeated}"
                )
            } else if idx % 4 == 2 {
                format!(
                    "interactive typing debounce benchmark {idx} for hybrid two tier search.{repeated}"
                )
            } else {
                format!(
                    "unrelated background chatter {idx} about build systems and formatting checks.{repeated}"
                )
            };
            let created_at = base_ts + idx as i64;
            let source_path_str = source_path.to_string_lossy().to_string();
            let title = format!("progressive fixture {idx}");

            conn.execute_compat(
                "INSERT INTO conversations (
                    id, agent_id, workspace_id, title, source_path, source_id, origin_host, started_at
                 ) VALUES (?1, ?2, ?3, ?4, ?5, ?6, NULL, ?7)",
                params![
                    conversation_id,
                    agent_id,
                    workspace_id,
                    title,
                    source_path_str.clone(),
                    source_id,
                    created_at
                ],
            )?;
            conn.execute_compat(
                "INSERT INTO messages (
                    id, conversation_id, idx, role, created_at, content
                 ) VALUES (?1, ?2, 0, 'user', ?3, ?4)",
                params![
                    i64::try_from(message_id)?,
                    conversation_id,
                    created_at,
                    content.clone()
                ],
            )?;
            message_rows.push((message_id, created_at, content.clone()));

            let normalized = NormalizedConversation {
                agent_slug: "codex".into(),
                external_id: Some(format!("progressive-{idx}")),
                title: Some(format!("progressive fixture {idx}")),
                workspace: Some(workspace_path.clone()),
                source_path,
                started_at: Some(created_at),
                ended_at: Some(created_at),
                metadata: json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: Some("user".into()),
                    created_at: Some(created_at),
                    content,
                    extra: json!({}),
                    snippets: Vec::new(),
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&normalized)?;
        }
        index.commit()?;

        assert_eq!(
            message_rows.len(),
            doc_count,
            "fixture should create the requested number of messages"
        );

        let fast_embedder = Arc::new(crate::search::hash_embedder::HashEmbedder::new(256));
        let quality_embedder = crate::search::hash_embedder::HashEmbedder::new(384);
        let filter_maps = SemanticFilterMaps::for_tests(
            HashMap::from([("codex".to_string(), u32::try_from(agent_id)?)]),
            HashMap::from([(
                workspace_path.to_string_lossy().to_string(),
                u32::try_from(workspace_id)?,
            )]),
            HashMap::from([(source_id.to_string(), source_hash)]),
            HashSet::new(),
        );
        let fast_path = dir.path().join("vector.fast.idx");
        let quality_path = dir.path().join("vector.quality.idx");

        let mut fast_writer = VectorIndex::create_with_revision(
            &fast_path,
            fast_embedder.id(),
            "rev-progressive-fast",
            fast_embedder.dimension(),
            frankensearch::index::Quantization::F16,
        )?;
        let mut quality_writer = VectorIndex::create_with_revision(
            &quality_path,
            quality_embedder.id(),
            "rev-progressive-quality",
            quality_embedder.dimension(),
            frankensearch::index::Quantization::F16,
        )?;

        for (message_id, created_at_ms, content) in &message_rows {
            let canonical = canonicalize_for_embedding(content);
            let doc_id = SemanticDocId {
                message_id: *message_id,
                chunk_idx: 0,
                agent_id: u32::try_from(agent_id)?,
                workspace_id: u32::try_from(workspace_id)?,
                source_id: source_hash,
                role: ROLE_USER,
                created_at_ms: *created_at_ms,
                content_hash: Some(content_hash(&canonical)),
            }
            .to_doc_id_string();

            let fast_vec = fast_embedder.embed_sync(content)?;
            fast_writer.write_record(&doc_id, &fast_vec)?;
            let quality_vec = quality_embedder.embed_sync(content)?;
            quality_writer.write_record(&doc_id, &quality_vec)?;
        }
        fast_writer.finish()?;
        quality_writer.finish()?;

        let reader = fs_cass_open_search_reader(dir.path(), ReloadPolicy::Manual).ok();
        let client = SearchClient {
            reader,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{}|schema:{}", CACHE_KEY_VERSION, FS_CASS_SCHEMA_HASH),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };
        let semantic_embedder: Arc<dyn Embedder> = fast_embedder;
        client.set_semantic_context(
            semantic_embedder,
            VectorIndex::open(&fast_path)?,
            filter_maps,
            None,
            Some(fast_path),
        )?;

        Ok(ProgressiveHybridFixture {
            _dir: dir,
            client: Arc::new(client),
            query,
        })
    }

    fn sanitize_query(raw: &str) -> String {
        nfc_sanitize_query(raw)
    }

    fn parse_boolean_query(query: &str) -> Vec<FsCassQueryToken> {
        fs_cass_parse_boolean_query(query)
    }

    fn sqlite_master_name_count(db_path: &Path, name: &str) -> Result<i64> {
        let conn = FrankenConnection::open(db_path.to_string_lossy().as_ref())?;
        Ok(conn.query_row_map(
            "SELECT COUNT(*) FROM sqlite_master WHERE name = ?1",
            &[ParamValue::from(name)],
            |row| row.get_typed(0),
        )?)
    }

    type QueryToken = FsCassQueryToken;
    type WildcardPattern = FsCassWildcardPattern;
    type QueryTokenList = Vec<QueryToken>;

    #[test]
    #[ignore = "profiling harness for live hybrid progressive search"]
    fn progressive_hybrid_profile_harness() -> Result<()> {
        let fixture = build_progressive_hybrid_fixture()?;
        let runtime = asupersync::runtime::RuntimeBuilder::current_thread()
            .build()
            .map_err(|err| anyhow!("build test runtime failed: {err}"))?;
        let iterations = 24usize;

        runtime.block_on(async {
            let cx = FsCx::for_request();
            fixture
                .client
                .search_progressive_with_callback(
                    ProgressiveSearchRequest {
                        cx: &cx,
                        query: &fixture.query,
                        filters: SearchFilters::default(),
                        limit: 16,
                        sparse_threshold: 0,
                        field_mask: FieldMask::new(false, true, true, true),
                        mode: SearchMode::Hybrid,
                    },
                    |_| {},
                )
                .await
        })?;

        let mut initial_events = 0usize;
        let mut refined_events = 0usize;
        let mut total_hits = 0usize;
        for _ in 0..iterations {
            let mut refinement_error = None;
            runtime.block_on(async {
                let cx = FsCx::for_request();
                fixture
                    .client
                    .search_progressive_with_callback(
                        ProgressiveSearchRequest {
                            cx: &cx,
                            query: &fixture.query,
                            filters: SearchFilters::default(),
                            limit: 16,
                            sparse_threshold: 0,
                            field_mask: FieldMask::new(false, true, true, true),
                            mode: SearchMode::Hybrid,
                        },
                        |event| match event {
                            ProgressiveSearchEvent::Phase { kind, result, .. } => {
                                assert!(
                                    !result.hits.is_empty(),
                                    "progressive harness expects non-empty hits for each phase"
                                );
                                total_hits += result.hits.len();
                                match kind {
                                    ProgressivePhaseKind::Initial => initial_events += 1,
                                    ProgressivePhaseKind::Refined => refined_events += 1,
                                }
                            }
                            ProgressiveSearchEvent::RefinementFailed { error, .. } => {
                                refinement_error = Some(error);
                            }
                        },
                    )
                    .await
            })?;
            if let Some(error) = refinement_error {
                bail!("progressive harness refinement failed: {error}");
            }
        }

        assert_eq!(initial_events, iterations);
        assert_eq!(refined_events, iterations);
        assert!(
            total_hits >= iterations.saturating_mul(16),
            "harness should observe a full page for each phase"
        );

        Ok(())
    }

    // ==========================================================================
    // StringInterner Tests (Opt 2.3)
    // ==========================================================================

    #[test]
    fn interner_returns_same_arc_for_same_string() {
        let interner = StringInterner::new(100);

        let s1 = interner.intern("test_query");
        let s2 = interner.intern("test_query");

        // Should be the exact same Arc (pointer equality)
        assert!(Arc::ptr_eq(&s1, &s2));
        assert_eq!(&*s1, "test_query");
    }

    #[test]
    fn interner_different_strings_return_different_arcs() {
        let interner = StringInterner::new(100);

        let s1 = interner.intern("query1");
        let s2 = interner.intern("query2");

        assert!(!Arc::ptr_eq(&s1, &s2));
        assert_eq!(&*s1, "query1");
        assert_eq!(&*s2, "query2");
    }

    #[test]
    fn interner_handles_empty_string() {
        let interner = StringInterner::new(100);

        let s1 = interner.intern("");
        let s2 = interner.intern("");

        assert!(Arc::ptr_eq(&s1, &s2));
        assert_eq!(&*s1, "");
    }

    #[test]
    fn interner_handles_unicode() {
        let interner = StringInterner::new(100);

        let s1 = interner.intern("测试查询");
        let s2 = interner.intern("测试查询");
        let s3 = interner.intern("emoji 🔍 search");

        assert!(Arc::ptr_eq(&s1, &s2));
        assert_eq!(&*s3, "emoji 🔍 search");
    }

    #[test]
    fn interner_respects_lru_eviction() {
        let interner = StringInterner::new(3);

        let _s1 = interner.intern("query1");
        let _s2 = interner.intern("query2");
        let _s3 = interner.intern("query3");

        assert_eq!(interner.len(), 3);

        // This should evict query1 (LRU)
        let _s4 = interner.intern("query4");

        assert_eq!(interner.len(), 3);

        // query1 should now get a NEW Arc (was evicted)
        let s1_new = interner.intern("query1");
        assert_eq!(&*s1_new, "query1");
    }

    #[test]
    fn interner_concurrent_access() {
        use std::thread;

        let interner = Arc::new(StringInterner::new(1000));
        let queries: Vec<String> = (0..100).map(|i| format!("query_{}", i)).collect();

        let handles: Vec<_> = (0..4)
            .map(|_| {
                let interner = Arc::clone(&interner);
                let queries = queries.clone();

                thread::spawn(move || {
                    for _ in 0..10 {
                        for query in &queries {
                            let _ = interner.intern(query);
                        }
                    }
                })
            })
            .collect();

        for handle in handles {
            handle.join().unwrap();
        }

        // Verify all queries are interned correctly
        for query in &queries {
            let s1 = interner.intern(query);
            let s2 = interner.intern(query);
            assert!(Arc::ptr_eq(&s1, &s2));
        }
    }

    // ==========================================================================
    // QueryTermsLower Tests (Opt 2.4)
    // ==========================================================================

    #[test]
    fn query_terms_lower_basic() {
        let terms = QueryTermsLower::from_query("Hello World");

        assert_eq!(terms.query_lower, "hello world");
        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["hello", "world"]);
    }

    #[test]
    fn query_terms_lower_empty() {
        let terms = QueryTermsLower::from_query("");

        assert!(terms.is_empty());
        assert_eq!(terms.tokens().count(), 0);
    }

    #[test]
    fn query_terms_lower_single_term() {
        let terms = QueryTermsLower::from_query("TEST");

        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["test"]);
    }

    #[test]
    fn query_terms_lower_with_punctuation() {
        let terms = QueryTermsLower::from_query("hello, world! how's it?");

        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["hello", "world", "how", "s", "it"]);
    }

    #[test]
    fn query_terms_lower_unicode() {
        let terms = QueryTermsLower::from_query("Héllo Wörld");

        assert_eq!(terms.query_lower, "héllo wörld");
        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["héllo", "wörld"]);
    }

    #[test]
    fn query_terms_lower_bloom_mask() {
        let terms = QueryTermsLower::from_query("test");

        // Bloom mask should be non-zero for non-empty query
        assert_ne!(terms.bloom_mask(), 0);

        // Same query should produce same bloom mask
        let terms2 = QueryTermsLower::from_query("test");
        assert_eq!(terms.bloom_mask(), terms2.bloom_mask());
    }

    #[test]
    fn hit_matches_with_precomputed_terms() {
        let hit = SearchHit {
            title: "Test Title".into(),
            snippet: "".into(),
            content: "hello world content".into(),
            content_hash: stable_content_hash("hello world content"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let cached = cached_hit_from(&hit);

        // Test with precomputed terms
        let terms = QueryTermsLower::from_query("hello");
        assert!(hit_matches_query_cached_precomputed(&cached, &terms));

        let terms_miss = QueryTermsLower::from_query("missing");
        assert!(!hit_matches_query_cached_precomputed(&cached, &terms_miss));
    }

    // ==========================================================================
    // Quickselect Top-K Tests (Opt 2.5)
    // ==========================================================================

    fn make_fused_hit(
        id: &str,
        rrf: f32,
        lexical: Option<usize>,
        semantic: Option<usize>,
    ) -> FusedHit {
        FusedHit {
            key: SearchHitKey {
                source_id: "local".to_string(),
                source_path: id.to_string(),
                conversation_id: None,
                title: String::new(),
                line_number: None,
                created_at: None,
                content_hash: 0,
            },
            score: HybridScore {
                rrf,
                lexical_rank: lexical,
                semantic_rank: semantic,
                lexical_score: None,
                semantic_score: None,
            },
            hit: SearchHit {
                title: id.into(),
                snippet: "".into(),
                content: "".into(),
                content_hash: 0,
                score: rrf,
                source_path: id.into(),
                agent: "test".into(),
                workspace: "test".into(),
                workspace_original: None,
                created_at: None,
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        }
    }

    fn make_federated_merge_hit(id: &str, agent: &str) -> SearchHit {
        SearchHit {
            title: id.into(),
            snippet: String::new(),
            content: id.into(),
            content_hash: stable_content_hash(id),
            score: 0.0,
            source_path: format!("{id}.jsonl"),
            agent: agent.into(),
            workspace: "workspace".into(),
            workspace_original: None,
            created_at: Some(1_700_000_000_000),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        }
    }

    fn make_federated_ranked_hit(
        shard_index: usize,
        shard_rank: usize,
        id: &str,
    ) -> FederatedRankedHit {
        FederatedRankedHit {
            hit: make_federated_merge_hit(id, &format!("shard-{shard_index}")),
            shard_index,
            shard_rank,
            fused_score: federated_rrf_score(shard_rank),
        }
    }

    #[test]
    fn federated_merge_orders_equal_rank_hits_by_stable_hit_key() {
        let merged = merge_federated_ranked_hits(vec![
            make_federated_ranked_hit(2, 0, "zeta"),
            make_federated_ranked_hit(0, 0, "bravo"),
            make_federated_ranked_hit(1, 0, "alpha"),
        ]);

        let paths = merged
            .iter()
            .map(|hit| hit.source_path.as_str())
            .collect::<Vec<_>>();
        assert_eq!(paths, vec!["alpha.jsonl", "bravo.jsonl", "zeta.jsonl"]);
        assert!(
            merged
                .iter()
                .all(|hit| (hit.score - federated_rrf_score(0)).abs() < f32::EPSILON),
            "equal per-shard rank should produce equal RRF scores"
        );
    }

    #[test]
    fn federated_merge_keeps_rrf_rank_ahead_of_stable_key() {
        let merged = merge_federated_ranked_hits(vec![
            make_federated_ranked_hit(0, 1, "alpha"),
            make_federated_ranked_hit(1, 0, "zeta"),
        ]);

        let paths = merged
            .iter()
            .map(|hit| hit.source_path.as_str())
            .collect::<Vec<_>>();
        assert_eq!(paths, vec!["zeta.jsonl", "alpha.jsonl"]);
        assert!(merged[0].score > merged[1].score);
    }

    #[test]
    fn federated_merge_uses_shard_index_as_duplicate_final_tiebreak() {
        let merged = merge_federated_ranked_hits(vec![
            FederatedRankedHit {
                hit: make_federated_merge_hit("same", "shard-2"),
                shard_index: 2,
                shard_rank: 0,
                fused_score: federated_rrf_score(0),
            },
            FederatedRankedHit {
                hit: make_federated_merge_hit("same", "shard-0"),
                shard_index: 0,
                shard_rank: 0,
                fused_score: federated_rrf_score(0),
            },
        ]);

        assert_eq!(merged[0].agent, "shard-0");
        assert_eq!(merged[1].agent, "shard-2");
    }

    #[test]
    fn top_k_fused_basic() {
        let hits = vec![
            make_fused_hit("a", 1.0, Some(0), None),
            make_fused_hit("b", 3.0, Some(1), None),
            make_fused_hit("c", 2.0, Some(2), None),
            make_fused_hit("d", 5.0, Some(3), None),
            make_fused_hit("e", 4.0, Some(4), None),
        ];

        let top = top_k_fused(hits, 3);

        assert_eq!(top.len(), 3);
        assert_eq!(top[0].key.source_path, "d"); // 5.0
        assert_eq!(top[1].key.source_path, "e"); // 4.0
        assert_eq!(top[2].key.source_path, "b"); // 3.0
    }

    #[test]
    fn top_k_fused_empty() {
        let hits: Vec<FusedHit> = vec![];
        let top = top_k_fused(hits, 10);
        assert!(top.is_empty());
    }

    #[test]
    fn top_k_fused_k_zero() {
        let hits = vec![
            make_fused_hit("a", 1.0, Some(0), None),
            make_fused_hit("b", 2.0, Some(1), None),
        ];
        let top = top_k_fused(hits, 0);
        assert!(top.is_empty());
    }

    #[test]
    fn top_k_fused_k_larger_than_n() {
        let hits = vec![
            make_fused_hit("a", 1.0, Some(0), None),
            make_fused_hit("b", 2.0, Some(1), None),
        ];

        let top = top_k_fused(hits, 10);

        assert_eq!(top.len(), 2);
        assert_eq!(top[0].key.source_path, "b"); // 2.0
        assert_eq!(top[1].key.source_path, "a"); // 1.0
    }

    #[test]
    fn top_k_fused_k_equals_n() {
        let hits = vec![
            make_fused_hit("a", 3.0, Some(0), None),
            make_fused_hit("b", 1.0, Some(1), None),
            make_fused_hit("c", 2.0, Some(2), None),
        ];

        let top = top_k_fused(hits, 3);

        assert_eq!(top.len(), 3);
        assert_eq!(top[0].key.source_path, "a"); // 3.0
        assert_eq!(top[1].key.source_path, "c"); // 2.0
        assert_eq!(top[2].key.source_path, "b"); // 1.0
    }

    #[test]
    fn top_k_fused_k_one() {
        let hits = vec![
            make_fused_hit("a", 1.0, Some(0), None),
            make_fused_hit("b", 3.0, Some(1), None),
            make_fused_hit("c", 2.0, Some(2), None),
        ];

        let top = top_k_fused(hits, 1);

        assert_eq!(top.len(), 1);
        assert_eq!(top[0].key.source_path, "b");
        assert_eq!(top[0].score.rrf, 3.0);
    }

    #[test]
    fn top_k_fused_duplicate_scores() {
        let hits = vec![
            make_fused_hit("a", 2.0, Some(0), None),
            make_fused_hit("b", 2.0, Some(1), None),
            make_fused_hit("c", 2.0, Some(2), None),
            make_fused_hit("d", 1.0, Some(3), None),
        ];

        let top = top_k_fused(hits, 2);

        assert_eq!(top.len(), 2);
        // All have same score, so order is by key (deterministic tie-breaking)
        assert_eq!(top[0].score.rrf, 2.0);
        assert_eq!(top[1].score.rrf, 2.0);
    }

    #[test]
    fn top_k_fused_dual_source_tiebreaker() {
        // Hits with same RRF score, but some have both lexical and semantic ranks
        let hits = vec![
            make_fused_hit("a", 2.0, Some(0), None),    // lexical only
            make_fused_hit("b", 2.0, Some(1), Some(0)), // both sources
            make_fused_hit("c", 2.0, None, Some(1)),    // semantic only
        ];

        let top = top_k_fused(hits, 3);

        assert_eq!(top.len(), 3);
        // Dual-source hit should come first
        assert_eq!(top[0].key.source_path, "b");
    }

    #[test]
    fn top_k_fused_large_input_uses_quickselect() {
        // Create input larger than QUICKSELECT_THRESHOLD to trigger quickselect path
        let hits: Vec<FusedHit> = (0..100)
            .map(|i| make_fused_hit(&format!("hit_{}", i), i as f32, Some(i), None))
            .collect();

        let top = top_k_fused(hits, 10);

        assert_eq!(top.len(), 10);
        // Should be sorted descending: hit_99, hit_98, ... hit_90
        for (i, hit) in top.iter().enumerate() {
            assert_eq!(hit.key.source_path, format!("hit_{}", 99 - i));
            assert_eq!(hit.score.rrf, (99 - i) as f32);
        }
    }

    #[test]
    fn top_k_fused_equivalence_with_full_sort() {
        // Verify quickselect produces same results as full sort
        for n in [10, 50, 100, 200] {
            for k in [1, 5, 10, 25] {
                if k > n {
                    continue;
                }

                let hits: Vec<FusedHit> = (0..n)
                    .map(|i| {
                        // Pseudo-random scores using simple hash
                        let score = ((i * 17 + 7) % 1000) as f32;
                        make_fused_hit(&format!("hit_{}", i), score, Some(i), None)
                    })
                    .collect();

                // Baseline: full sort
                let mut baseline = hits.clone();
                baseline.sort_by(cmp_fused_hit_desc);
                baseline.truncate(k);

                // Quickselect
                let quickselect = top_k_fused(hits, k);

                // Verify same length
                assert_eq!(quickselect.len(), baseline.len(), "n={}, k={}", n, k);

                // Verify same elements in same order
                for (q, b) in quickselect.iter().zip(baseline.iter()) {
                    assert_eq!(
                        q.key.source_path, b.key.source_path,
                        "n={}, k={}: mismatch",
                        n, k
                    );
                    assert_eq!(q.score.rrf, b.score.rrf, "n={}, k={}: score mismatch", n, k);
                }
            }
        }
    }

    #[test]
    fn cmp_fused_hit_desc_basic_ordering() {
        let a = make_fused_hit("a", 2.0, Some(0), None);
        let b = make_fused_hit("b", 3.0, Some(1), None);

        // Higher score should come first (compare returns Less)
        assert_eq!(cmp_fused_hit_desc(&a, &b), CmpOrdering::Greater);
        assert_eq!(cmp_fused_hit_desc(&b, &a), CmpOrdering::Less);
        assert_eq!(cmp_fused_hit_desc(&a, &a), CmpOrdering::Equal);
    }

    // ==========================================================================
    // Original Tests
    // ==========================================================================

    #[test]
    fn cache_enforces_prefix_matching() {
        // Hit contains "arrow"
        let hit = SearchHit {
            title: "test".into(),
            snippet: "".into(),
            content: "arrow".into(),
            content_hash: stable_content_hash("arrow"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let cached = CachedHit {
            hit: hit.clone(),
            lc_content: "arrow".into(),
            lc_title: Some("test".into()),
            bloom64: u64::MAX, // Bypass bloom filter
        };

        // Query "row" is contained in "arrow" but is NOT a prefix.
        // It should NOT match if we are enforcing prefix semantics.
        let matched = hit_matches_query_cached(&cached, "row");

        assert!(
            !matched,
            "Query 'row' should NOT match content 'arrow' (prefix match required)"
        );
    }

    #[test]
    fn search_deduplication_across_pages_repro() {
        // Distinct sessions with identical content should remain visible across
        // pages. Global pagination still has to happen after deduplication, but
        // dedup itself only coalesces hits that share message-level provenance.

        let dir = TempDir::new().unwrap();
        let index_path = dir.path();
        let mut index = TantivyIndex::open_or_create(index_path).unwrap();

        // Add two documents with IDENTICAL content but distinct other fields.
        // Tantivy scores them. If query matches both equally, one comes first.
        // We'll use different source paths to ensure they are distinct hits initially.
        let msg1 = NormalizedMessage {
            idx: 0,
            role: "user".into(),
            author: None,
            created_at: Some(1000),
            content: "duplicate content".into(),
            extra: serde_json::json!({}),
            snippets: Vec::new(),
            invocations: Vec::new(),
        };
        let conv1 = NormalizedConversation {
            agent_slug: "agent1".into(),
            external_id: None,
            title: None,
            workspace: None,
            source_path: "path/1".into(),
            started_at: None,
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![msg1],
        };

        let msg2 = NormalizedMessage {
            idx: 0,
            role: "user".into(),
            author: None,
            created_at: Some(2000),              // Different timestamp
            content: "duplicate content".into(), // SAME content
            extra: serde_json::json!({}),
            snippets: Vec::new(),
            invocations: Vec::new(),
        };
        let conv2 = NormalizedConversation {
            agent_slug: "agent1".into(),
            external_id: None,
            title: None,
            workspace: None,
            source_path: "path/2".into(), // Different source path
            started_at: None,
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![msg2],
        };

        index.add_conversation(&conv1).unwrap();
        index.add_conversation(&conv2).unwrap();
        index.commit().unwrap();

        let client = SearchClient::open(index_path, None).unwrap().unwrap();

        // Search page 1: limit 1, offset 0
        let page1 = client
            .search("duplicate", SearchFilters::default(), 1, 0, FieldMask::FULL)
            .unwrap();
        assert_eq!(page1.len(), 1);

        // Search page 2: limit 1, offset 1
        let page2 = client
            .search("duplicate", SearchFilters::default(), 1, 1, FieldMask::FULL)
            .unwrap();

        assert_eq!(page2.len(), 1);
        assert_ne!(page1[0].source_path, page2[0].source_path);
    }

    #[test]
    fn cache_skips_complex_queries() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        // Wildcard query should skip cache logic entirely (no miss recorded)
        let _ = client.search("foo*", SearchFilters::default(), 10, 0, FieldMask::FULL);
        let stats = client.cache_stats();
        assert_eq!(
            stats.cache_miss, 0,
            "Wildcard query should not trigger cache miss"
        );

        // Boolean query should skip cache
        let _ = client.search(
            "foo OR bar",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        );
        let stats = client.cache_stats();
        assert_eq!(
            stats.cache_miss, 0,
            "Boolean query should not trigger cache miss"
        );

        // Simple query should trigger miss
        let _ = client.search("simple", SearchFilters::default(), 10, 0, FieldMask::FULL);
        let stats = client.cache_stats();
        assert_eq!(
            stats.cache_miss, 1,
            "Simple query should trigger cache miss"
        );
    }

    #[test]
    fn cache_prefix_lookup_handles_utf8_boundaries() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = vec![SearchHit {
            title: "こんにちは".into(),
            snippet: String::new(),
            content: "こんにちは 世界".into(),
            content_hash: stable_content_hash("こんにちは 世界"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        }];

        client.put_cache("こん", &SearchFilters::default(), &hits);

        let cached = client
            .cached_prefix_hits("こんにちは", &SearchFilters::default())
            .unwrap();
        assert_eq!(cached.len(), 1);
        assert_eq!(cached[0].hit.title, "こんにちは");
    }

    #[test]
    fn bloom_gate_rejects_missing_terms() {
        let hit = SearchHit {
            title: "hello world".into(),
            snippet: "hello world".into(),
            content: "hello world".into(),
            content_hash: stable_content_hash("hello world"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let cached = cached_hit_from(&hit);
        assert!(hit_matches_query_cached(&cached, "hello"));
        assert!(!hit_matches_query_cached(&cached, "missing"));

        let metrics = Metrics::default();
        metrics.inc_cache_hits();
        metrics.inc_cache_miss();
        metrics.inc_cache_shortfall();
        metrics.inc_reload();
        let (hits, miss, shortfall, reloads, _) = metrics.snapshot_all();
        assert_eq!((hits, miss, shortfall, reloads), (1, 1, 1, 1));
    }

    #[test]
    fn progressive_lexical_hit_omits_unused_content() {
        let hit = SearchHit {
            title: "hello world".into(),
            snippet: "hello **world**".into(),
            content: "hello world from a much larger conversation body".into(),
            content_hash: stable_content_hash("hello world from a much larger conversation body"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: Some(3),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let snippet_only =
            ProgressiveLexicalHit::from_search_hit(&hit, FieldMask::new(false, true, true, true));
        assert_eq!(snippet_only.title, hit.title);
        assert_eq!(snippet_only.snippet, hit.snippet);
        assert!(
            snippet_only.content.is_empty(),
            "snippet-only progressive cache should not retain full content"
        );
        assert_eq!(snippet_only.match_type, hit.match_type);
        assert_eq!(snippet_only.line_number, hit.line_number);
        assert_eq!(snippet_only.source_path, hit.source_path);
        assert_eq!(snippet_only.agent, hit.agent);
        assert_eq!(snippet_only.workspace, hit.workspace);

        let full =
            ProgressiveLexicalHit::from_search_hit(&hit, FieldMask::new(true, true, true, true));
        assert_eq!(full.content, hit.content);
    }

    #[test]
    fn progressive_phase_reuses_lexical_cache_without_db_hydration() -> Result<()> {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };
        let field_mask = FieldMask::new(false, true, true, true);
        let lexical_hit = SearchHit {
            title: "lexical title".into(),
            snippet: "lexical snippet".into(),
            content: "full lexical body".into(),
            content_hash: stable_content_hash("full lexical body"),
            score: 0.0,
            source_path: "/tmp/session.jsonl".into(),
            agent: "codex".into(),
            workspace: "/tmp".into(),
            workspace_original: Some("/original".into()),
            created_at: Some(1_700_000_000_000),
            line_number: Some(7),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let mut lexical_cache = ProgressiveLexicalCache::default();
        lexical_cache.hits_by_message.insert(
            42,
            ProgressiveLexicalHit::from_search_hit(&lexical_hit, field_mask),
        );

        let hash_hex = "00".repeat(32);
        let results = vec![FsScoredResult {
            doc_id: format!("m|42|0|1|1|1|1|1700000000000|{hash_hex}"),
            score: 0.91,
            source: FsScoreSource::Lexical,
            index: None,
            fast_score: None,
            quality_score: None,
            lexical_score: Some(0.91),
            rerank_score: None,
            explanation: None,
            metadata: None,
        }];

        let result = client.progressive_phase_to_result(
            &results,
            ProgressivePhaseContext {
                query: "merged title",
                filters: &SearchFilters::default(),
                field_mask,
                lexical_cache: Some(&lexical_cache),
                limit: 1,
                fetch_limit: 1,
            },
        )?;

        assert_eq!(result.hits.len(), 1);
        assert_eq!(result.hits[0].title, lexical_hit.title);
        assert_eq!(result.hits[0].snippet, lexical_hit.snippet);
        assert!(
            result.hits[0].content.is_empty(),
            "masked lexical cache should still avoid carrying full content"
        );
        assert_eq!(result.hits[0].source_path, lexical_hit.source_path);
        assert_eq!(result.hits[0].score, 0.91);

        Ok(())
    }

    #[test]
    fn search_returns_results_with_filters_and_pagination() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("hello world convo".into()),
            workspace: Some(std::path::PathBuf::from("/tmp/workspace")),
            source_path: dir.path().join("rollout-1.jsonl"),
            started_at: Some(1_700_000_000_000),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: Some("me".into()),
                created_at: Some(1_700_000_000_000),
                content: "hello rust world".into(),
                extra: serde_json::json!({}),
                snippets: vec![NormalizedSnippet {
                    file_path: None,
                    start_line: None,
                    end_line: None,
                    language: None,
                    snippet_text: None,
                }],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".into());

        let hits = client.search("hello", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].agent, "codex");
        assert!(hits[0].snippet.contains("hello"));
        Ok(())
    }

    #[test]
    fn search_honors_created_range_and_workspace() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv_a = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("needle one".into()),
            workspace: Some(std::path::PathBuf::from("/ws/a")),
            source_path: dir.path().join("a.jsonl"),
            started_at: Some(10),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(10),
                content: "alpha needle".into(),
                extra: serde_json::json!({}),
                snippets: vec![NormalizedSnippet {
                    file_path: None,
                    start_line: None,
                    end_line: None,
                    language: None,
                    snippet_text: None,
                }],
                invocations: Vec::new(),
            }],
        };
        let conv_b = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("needle two".into()),
            workspace: Some(std::path::PathBuf::from("/ws/b")),
            source_path: dir.path().join("b.jsonl"),
            started_at: Some(20),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(20),
                content: "\nneedle second line".into(),
                extra: serde_json::json!({}),
                snippets: vec![NormalizedSnippet {
                    file_path: None,
                    start_line: None,
                    end_line: None,
                    language: None,
                    snippet_text: None,
                }],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv_a)?;
        index.add_conversation(&conv_b)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let mut filters = SearchFilters::default();
        filters.workspaces.insert("/ws/b".into());
        filters.created_from = Some(15);
        filters.created_to = Some(25);

        let hits = client.search("needle", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].workspace, "/ws/b");
        assert!(hits[0].snippet.contains("second line"));
        Ok(())
    }

    #[test]
    fn pagination_skips_results() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        for i in 0..3 {
            let conv = NormalizedConversation {
                agent_slug: "codex".into(),
                external_id: None,
                title: Some(format!("doc-{i}")),
                workspace: Some(std::path::PathBuf::from("/ws/p")),
                source_path: dir.path().join(format!("{i}.jsonl")),
                started_at: Some(100 + i),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100 + i),
                    // Use unique content for each doc to avoid deduplication
                    content: format!("pagination needle document number {i}"),
                    extra: serde_json::json!({}),
                    snippets: vec![NormalizedSnippet {
                        file_path: None,
                        start_line: None,
                        end_line: None,
                        language: None,
                        snippet_text: None,
                    }],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let hits = client.search(
            "pagination",
            SearchFilters::default(),
            1,
            1,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        Ok(())
    }

    #[test]
    fn search_matches_hyphenated_term() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("cma-es notes".into()),
            workspace: Some(std::path::PathBuf::from("/tmp/workspace")),
            source_path: dir.path().join("rollout-1.jsonl"),
            started_at: Some(1_700_000_000_000),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: Some("me".into()),
                created_at: Some(1_700_000_000_000),
                content: "Need CMA-ES strategy and CMA ES variants".into(),
                extra: serde_json::json!({}),
                snippets: vec![NormalizedSnippet {
                    file_path: None,
                    start_line: None,
                    end_line: None,
                    language: None,
                    snippet_text: None,
                }],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let hits = client.search("cma-es", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert!(hits[0].snippet.to_lowercase().contains("cma"));
        Ok(())
    }

    #[test]
    fn search_matches_prefix_edge_ngram() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("math logic".into()),
            workspace: Some(std::path::PathBuf::from("/ws/m")),
            source_path: dir.path().join("math.jsonl"),
            started_at: Some(1000),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1000),
                content: "please calculate the entropy".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "cal" should match "calculate"
        let hits = client.search("cal", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert!(hits[0].content.contains("calculate"));

        // "entr" should match "entropy"
        let hits = client.search("entr", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);

        Ok(())
    }

    #[test]
    fn search_matches_snake_case() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("code".into()),
            workspace: None,
            source_path: dir.path().join("c.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "check the my_variable_name please".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "vari" should match "variable" inside "my_variable_name"
        let hits = client.search("vari", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);

        // "my_variable" should match "my_variable_name" (because it splits to "my variable")
        let hits = client.search(
            "my_variable",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);

        Ok(())
    }

    #[test]
    fn search_matches_symbols_stripped() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("symbols".into()),
            workspace: None,
            source_path: dir.path().join("s.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "working with c++ and foo.bar today".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "c++" -> "c"
        let hits = client.search("c++", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);

        // "foo.bar" -> "foo", "bar"
        let hits = client.search("foo.bar", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);

        Ok(())
    }

    #[test]
    fn search_sets_match_type_for_wildcards() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("handlers".into()),
            workspace: None,
            source_path: dir.path().join("h.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "the request handler delegates".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        let exact = client.search("handler", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(exact[0].match_type, MatchType::Exact);

        let prefix = client.search("hand*", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(prefix[0].match_type, MatchType::Prefix);

        let suffix = client.search("*handler", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(suffix[0].match_type, MatchType::Suffix);

        let substring =
            client.search("*andle*", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(substring[0].match_type, MatchType::Substring);

        Ok(())
    }

    #[test]
    fn search_with_fallback_marks_implicit_wildcard() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("handlers".into()),
            workspace: None,
            source_path: dir.path().join("h2.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "the request handler delegates".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Base search for "andle" finds nothing; fallback "*andle*" should hit and mark implicit.
        let result = client.search_with_fallback(
            "andle",
            SearchFilters::default(),
            10,
            0,
            2,
            FieldMask::FULL,
        )?;
        assert!(result.wildcard_fallback);
        assert_eq!(result.hits.len(), 1);
        assert_eq!(result.hits[0].match_type, MatchType::ImplicitWildcard);

        Ok(())
    }

    #[test]
    fn sqlite_backend_skips_wildcard_queries() -> Result<()> {
        // Build a client with SQLite only; wildcard queries should short-circuit without errors.
        let conn = Connection::open(":memory:")?;
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.search("*handler", SearchFilters::default(), 5, 0, FieldMask::FULL)?;
        assert!(
            hits.is_empty(),
            "wildcard should skip sqlite fallback, not error"
        );

        Ok(())
    }

    #[test]
    fn sqlite_backend_handles_null_workspace() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(1, 1, NULL, 'local', NULL, 't', '/tmp/session.jsonl')",
        )?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(1, 1, 0, 'auth token failure', 42)")?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, NULL, ?5, ?6)",
            params![
                1_i64,
                "auth token failure",
                "t",
                "codex",
                "/tmp/session.jsonl",
                42_i64
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.search("auth", SearchFilters::default(), 5, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].workspace, "");
        assert_eq!(hits[0].line_number, Some(1));
        assert_eq!(hits[0].source_id, "local");
        assert_eq!(hits[0].origin_kind, "local");
        Ok(())
    }

    #[test]
    fn sqlite_backend_supports_legacy_fts_message_id_schema() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                message_id UNINDEXED,
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/legacy')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, 1, 'local', NULL, 'legacy title', '/tmp/legacy.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO messages(id, conversation_id, idx, content, created_at)
             VALUES(42, 1, 4, 'legacy auth token failure', 99)",
        )?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at, message_id)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)",
            params![
                1_i64,
                "legacy auth token failure",
                "legacy title",
                "codex",
                "/legacy",
                "/tmp/legacy.jsonl",
                99_i64,
                42_i64
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.search("auth", SearchFilters::default(), 5, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].title, "legacy title");
        assert_eq!(hits[0].source_path, "/tmp/legacy.jsonl");
        assert_eq!(hits[0].workspace, "/legacy");
        assert_eq!(hits[0].line_number, Some(5));
        assert_eq!(hits[0].content, "legacy auth token failure");
        Ok(())
    }

    #[test]
    fn tantivy_reader_skips_sqlite_fallback_on_empty_lexical_results() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        index.commit()?;
        let reader = fs_cass_open_search_reader(dir.path(), ReloadPolicy::Manual).ok();
        assert!(
            reader.is_some(),
            "test fixture should open a Tantivy reader even with an empty index"
        );

        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/sqlite-only')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, 1, 'local', NULL, 'sqlite fallback only', '/tmp/sqlite-only.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO messages(id, conversation_id, idx, content, created_at)
             VALUES(1, 1, 0, 'sqliteonlytoken overflow candidate', 42)",
        )?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                1_i64,
                "sqliteonlytoken overflow candidate",
                "sqlite fallback only",
                "codex",
                "/sqlite-only",
                "/tmp/sqlite-only.jsonl",
                42_i64
            ],
        )?;

        let client = SearchClient {
            reader,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let sqlite_hits = client.search_sqlite_fts5(
            Path::new(":memory:"),
            "sqliteonlytoken",
            SearchFilters::default(),
            5,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(
            sqlite_hits.len(),
            1,
            "fixture should prove sqlite fallback would have produced a hit"
        );

        let tantivy_authoritative_hits = client.search(
            "sqliteonlytoken",
            SearchFilters::default(),
            5,
            0,
            FieldMask::FULL,
        )?;
        assert!(
            tantivy_authoritative_hits.is_empty(),
            "a live Tantivy reader should prevent sqlite fallback from populating empty lexical results"
        );
        Ok(())
    }

    #[test]
    fn sqlite_guard_does_not_repair_fts_when_generation_key_stale() -> Result<()> {
        let temp_dir = TempDir::new()?;
        let db_path = temp_dir.path().join("stale-gen-fts.db");

        // Seed a DB with a conversation and indexed FTS content.
        {
            let storage = FrankenStorage::open(&db_path)?;
            let agent = Agent {
                id: None,
                slug: "codex".into(),
                name: "Codex".into(),
                version: None,
                kind: AgentKind::Cli,
            };
            let agent_id = storage.ensure_agent(&agent)?;
            let conversation = Conversation {
                id: None,
                agent_slug: "codex".into(),
                workspace: Some(PathBuf::from("/tmp/workspace")),
                external_id: Some("stale-gen-fts".into()),
                title: Some("Stale FTS generation".into()),
                source_path: PathBuf::from("/tmp/stale-gen-fts.jsonl"),
                started_at: Some(1_700_000_000_000),
                ended_at: Some(1_700_000_000_100),
                approx_tokens: Some(42),
                metadata_json: serde_json::Value::Null,
                messages: vec![Message {
                    id: None,
                    idx: 0,
                    role: MessageRole::User,
                    author: Some("user".into()),
                    created_at: Some(1_700_000_000_050),
                    content: "message that should remain queryable".into(),
                    extra_json: serde_json::Value::Null,
                    snippets: Vec::new(),
                }],
                source_id: "local".into(),
                origin_host: None,
            };
            storage.insert_conversation_tree(agent_id, None, &conversation)?;
        }

        let count_before = sqlite_master_name_count(&db_path, "fts_messages")
            .context("count schema rows before generation key deletion")?;

        // Simulate a stale generation by deleting the rebuild marker.
        // This is the condition ensure_fts_consistency_via_frankensqlite
        // detects to trigger a full FTS rebuild.
        {
            let conn = FrankenConnection::open(db_path.to_string_lossy().into_owned())?;
            conn.execute_compat(
                "DELETE FROM meta WHERE key = ?1",
                &[ParamValue::from("fts_frankensqlite_rebuild_generation")],
            )?;
        }

        // Opening via sqlite_guard() must remain read-only. A search path
        // should not trigger heavyweight derived-index repair.
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: Some(db_path.clone()),
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let guard = client
            .sqlite_guard()
            .context("open sqlite guard for stale generation fixture")?;
        assert!(guard.is_some(), "sqlite guard should open the db");
        let conn = guard
            .as_ref()
            .expect("sqlite guard should hold a connection");
        let no_params: [ParamValue; 0] = [];
        let cache_size: i64 =
            conn.query_row_map("PRAGMA cache_size;", &no_params, |row| row.get_typed(0))?;
        assert_eq!(
            cache_size, -SEARCH_SQLITE_HYDRATION_CACHE_KIB,
            "search hydration should not inherit the general storage cache profile"
        );
        drop(guard);

        // The read-only open must not rewrite the rebuild-generation marker.
        let conn = FrankenConnection::open(db_path.to_string_lossy().into_owned())?;
        let generation_after: Option<String> = conn
            .query_row_map(
                "SELECT value FROM meta WHERE key = ?1",
                &[ParamValue::from("fts_frankensqlite_rebuild_generation")],
                |row| row.get_typed(0),
            )
            .optional()?;
        assert!(
            generation_after.is_none(),
            "search sqlite guard must not mutate FTS rebuild metadata"
        );

        // Schema rows remain unchanged by the read-only open.
        let count_after = sqlite_master_name_count(&db_path, "fts_messages")
            .context("count schema rows after sqlite guard reopen")?;
        assert_eq!(
            count_after, count_before,
            "read-only reopen must leave FTS schema state unchanged"
        );

        Ok(())
    }

    #[test]
    fn sqlite_path_rusqlite_fallback_matches_hyphenated_ids_with_workspace_filter() -> Result<()> {
        fn fts_match_count(conn: &FrankenConnection, fts_query: &str) -> Result<Option<usize>> {
            let match_mode = SearchClient::sqlite_fts_match_mode(conn)?;
            let sql = format!(
                "SELECT COUNT(*) FROM fts_messages WHERE {}",
                SearchClient::sqlite_fts5_match_clause(match_mode)
            );
            let mut params = Vec::new();
            SearchClient::push_sqlite_fts5_match_params(&mut params, fts_query, match_mode);
            match franken_query_map_collect_retry(conn, &sql, &params, |row| row.get_typed(0)) {
                Ok(rows) => {
                    let count: i64 = rows.into_iter().next().unwrap_or(0);
                    Ok(Some(usize::try_from(count.max(0)).unwrap_or(usize::MAX)))
                }
                Err(err) if err.to_string().contains("no such function: MATCH/2") => Ok(None),
                Err(err) => Err(err.into()),
            }
        }

        let temp_dir = TempDir::new()?;
        let db_path = temp_dir.path().join("hyphenated-rusqlite-fallback.db");

        {
            let storage = FrankenStorage::open(&db_path)?;
            // V14 drops fts_messages during migration — run the lazy repair
            // so the direct INSERT INTO fts_messages below can land.
            storage.ensure_search_fallback_fts_consistency()?;
            let conn = storage.raw();
            conn.execute(
                "INSERT INTO agents(id, slug, name, kind, created_at, updated_at)
                 VALUES(1, 'codex', 'Codex', 'codex', 1, 1)",
            )?;
            conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/ws/alpha')")?;
            conn.execute("INSERT INTO workspaces(id, path) VALUES(2, '/ws/beta')")?;
            conn.execute(
                "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
                 VALUES(1, 1, 1, 'local', NULL, 'alpha bead', '/tmp/alpha.jsonl')",
            )?;
            conn.execute(
                "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
                 VALUES(2, 1, 2, 'local', NULL, 'beta bead', '/tmp/beta.jsonl')",
            )?;
            conn.execute(
                "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
                 VALUES(11, 1, 0, 'user', 'Need follow-up on br-123 root cause', 100)",
            )?;
            conn.execute(
                "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
                 VALUES(12, 2, 0, 'user', 'Need follow-up on br-123 user report', 101)",
            )?;
            conn.execute_compat(
                "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
                 VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
                &[
                    ParamValue::from(11_i64),
                    ParamValue::from("Need follow-up on br-123 root cause"),
                    ParamValue::from("alpha bead"),
                    ParamValue::from("codex"),
                    ParamValue::from("/ws/alpha"),
                    ParamValue::from("/tmp/alpha.jsonl"),
                    ParamValue::from(100_i64),
                ],
            )?;
            conn.execute_compat(
                "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
                 VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
                &[
                    ParamValue::from(12_i64),
                    ParamValue::from("Need follow-up on br-123 user report"),
                    ParamValue::from("beta bead"),
                    ParamValue::from("codex"),
                    ParamValue::from("/ws/beta"),
                    ParamValue::from("/tmp/beta.jsonl"),
                    ParamValue::from(101_i64),
                ],
            )?;
            let preclose_total_rows: i64 =
                conn.query_row_map("SELECT COUNT(*) FROM fts_messages", params![], |row| {
                    row.get_typed(0)
                })?;
            assert_eq!(
                preclose_total_rows, 2,
                "freshly seeded file-backed FTS should retain the inserted rows"
            );
            let transpiled = transpile_to_fts5("br-123").expect("transpiled fallback query");
            if let Some(match_count) = fts_match_count(conn, transpiled.as_str())? {
                assert_eq!(
                    match_count, 2,
                    "freshly seeded file-backed FTS should match the transpiled hyphenated query before reopen"
                );
            }
        }

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: Some(db_path),
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let guard = client.sqlite_guard()?;
        let conn = guard.as_ref().expect("sqlite guard should reopen file db");
        let reopened_total_rows: i64 =
            conn.query_row_map("SELECT COUNT(*) FROM fts_messages", params![], |row| {
                row.get_typed(0)
            })?;
        assert_eq!(
            reopened_total_rows, 2,
            "reopened file-backed FTS should still contain the seeded rows"
        );
        let transpiled = transpile_to_fts5("br-123").expect("transpiled fallback query");
        if let Some(match_count) = fts_match_count(conn, transpiled.as_str())? {
            assert_eq!(
                match_count, 2,
                "reopened file-backed FTS should still match the transpiled hyphenated query"
            );
        }
        drop(guard);

        let all_hits = client.search("br-123", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(all_hits.len(), 2);
        assert!(
            all_hits.iter().all(|hit| hit.content.contains("br-123")),
            "hyphenated bead IDs should survive the file-backed sqlite fallback path"
        );

        let leading_or_hits = client.search(
            "OR br-123",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(leading_or_hits.len(), 2);

        let dotted_hits = client.search(
            "br-123.jsonl",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(dotted_hits.len(), 2);

        let dotted_prefix_hits = client.search(
            "br-123.json*",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(dotted_prefix_hits.len(), 2);

        let prefix_hits =
            client.search("br-12*", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(prefix_hits.len(), 2);

        let filtered_hits = client.search(
            "br-123",
            SearchFilters {
                workspaces: HashSet::from_iter(["/ws/beta".to_string()]),
                ..SearchFilters::default()
            },
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(filtered_hits.len(), 1);
        assert_eq!(filtered_hits[0].workspace, "/ws/beta");
        assert_eq!(filtered_hits[0].source_path, "/tmp/beta.jsonl");
        assert!(filtered_hits[0].content.contains("br-123"));

        Ok(())
    }

    #[test]
    fn sqlite_backend_orders_hits_by_bm25_score() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/ws')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(1, 1, 1, 'local', NULL, 'best', '/tmp/best.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(2, 1, 1, 'local', NULL, 'worse', '/tmp/worse.jsonl')",
        )?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(7, 1, 0, 'auth auth auth failure', 42)")?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(8, 2, 0, 'auth failure', 43)")?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                7_i64,
                "auth auth auth failure",
                "best",
                "codex",
                "/ws",
                "/tmp/best.jsonl",
                42_i64
            ],
        )?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                8_i64,
                "auth failure",
                "worse",
                "codex",
                "/ws",
                "/tmp/worse.jsonl",
                43_i64
            ],
        )?;
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };
        let direct_hits = client.search_sqlite_fts5(
            Path::new(":memory:"),
            "auth",
            SearchFilters::default(),
            5,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(direct_hits.len(), 2);

        let hits = client.search("auth", SearchFilters::default(), 5, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 2);
        assert_eq!(hits[0].title, "best");
        assert_eq!(hits[1].title, "worse");
        assert!(hits[0].score > hits[1].score);

        Ok(())
    }

    #[test]
    fn sqlite_fts5_ranked_phase_defers_content_decode_until_after_limit() {
        let (rank_sql, params) = SearchClient::sqlite_fts5_rank_query(
            "auth",
            &SearchFilters::default(),
            50,
            0,
            false,
            SqliteFtsMatchMode::Table,
        );
        let hydrate_sql = SearchClient::sqlite_fts5_hydrate_query(
            2,
            FieldMask::new(true, true, true, true),
            false,
        );

        assert!(
            !rank_sql.contains("fts_messages.content"),
            "rank query must not decode large content rows before LIMIT"
        );
        assert!(
            hydrate_sql.contains("fts_messages.content"),
            "hydration query should still provide requested content"
        );
        assert!(
            rank_sql.contains("LIMIT ? OFFSET ?"),
            "rank query must apply page bounds before hydration"
        );
        assert_eq!(params.len(), 3, "fts query plus limit and offset params");
    }

    #[test]
    fn sqlite_fts5_hydration_chunks_stay_below_bind_variable_limit() {
        let oversized_row_count = SQLITE_MAX_VARIABLE_NUMBER + 1;
        let unchunked_sql = SearchClient::sqlite_fts5_hydrate_query(
            oversized_row_count,
            FieldMask::new(true, true, true, true),
            false,
        );
        assert!(
            unchunked_sql.matches('?').count() > SQLITE_MAX_VARIABLE_NUMBER,
            "the pre-fix one-shot hydration query would exceed frankensqlite's bind limit"
        );

        let ranked_rows: Vec<(i64, f64)> = (0..(SQLITE_FTS5_HYDRATE_PARAM_CHUNK + 17))
            .map(|idx| (idx as i64, idx as f64))
            .collect();
        let chunk_sizes: Vec<usize> = SearchClient::sqlite_fts5_hydrate_row_chunks(&ranked_rows)
            .map(<[(i64, f64)]>::len)
            .collect();

        assert_eq!(
            chunk_sizes,
            vec![SQLITE_FTS5_HYDRATE_PARAM_CHUNK, 17],
            "large fallback pages must hydrate in bounded chunks while preserving rank windows"
        );
        assert!(
            chunk_sizes
                .iter()
                .all(|chunk_size| *chunk_size <= SQLITE_MAX_VARIABLE_NUMBER),
            "every hydration chunk must fit under frankensqlite's bind-variable ceiling"
        );
    }

    #[test]
    fn tantivy_fallback_hydration_narrows_by_normalized_source_before_message_lookup() -> Result<()>
    {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                source_id TEXT,
                origin_host TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER NOT NULL,
                content TEXT NOT NULL,
                UNIQUE(conversation_id, idx)
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute(
            "INSERT INTO conversations(id, source_id, origin_host, source_path)
             VALUES(1, '', 'devbox', '/tmp/shared-fallback.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO conversations(id, source_id, origin_host, source_path)
             VALUES(2, 'local', NULL, '/tmp/shared-fallback.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO messages(id, conversation_id, idx, content)
             VALUES(10, 1, 2, 'remote fallback content')",
        )?;
        conn.execute(
            "INSERT INTO messages(id, conversation_id, idx, content)
             VALUES(20, 2, 2, 'local content must not win')",
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let fallback_key = (
            "devbox".to_string(),
            "/tmp/shared-fallback.jsonl".to_string(),
            2,
        );
        let (_, hydrated_fallback) =
            client.hydrate_tantivy_hit_contents(&[], std::slice::from_ref(&fallback_key))?;

        assert_eq!(
            hydrated_fallback.get(&fallback_key).map(String::as_str),
            Some("remote fallback content")
        );

        Ok(())
    }

    #[test]
    fn exact_content_hydration_returns_only_requested_message_indices() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER NOT NULL,
                content TEXT NOT NULL,
                UNIQUE(conversation_id, idx)
             );",
        )?;

        for idx in 0..8 {
            conn.execute(&format!(
                "INSERT INTO messages(conversation_id, idx, content)
                 VALUES(1, {idx}, 'conversation one row {idx}')"
            ))?;
        }
        conn.execute(
            "INSERT INTO messages(conversation_id, idx, content)
             VALUES(2, 0, 'conversation two row 0')",
        )?;

        let hydrated =
            hydrate_message_content_by_conversation(&conn, &[(1, 6), (1, 2), (2, 0), (1, 99)])?;

        assert_eq!(hydrated.len(), 3);
        assert_eq!(
            hydrated.get(&(1, 2)).map(String::as_str),
            Some("conversation one row 2")
        );
        assert_eq!(
            hydrated.get(&(1, 6)).map(String::as_str),
            Some("conversation one row 6")
        );
        assert_eq!(
            hydrated.get(&(2, 0)).map(String::as_str),
            Some("conversation two row 0")
        );
        assert!(!hydrated.contains_key(&(1, 99)));

        Ok(())
    }

    #[test]
    fn sqlite_backend_generates_snippet_from_content() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/ws')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(1, 1, 1, 'local', NULL, 'snippet title', '/tmp/snippet.jsonl')",
        )?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(1, 1, 0, 'alpha beta gamma delta epsilon zeta eta theta', 42)")?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                1_i64,
                "alpha beta gamma delta epsilon zeta eta theta",
                "snippet title",
                "codex",
                "/ws",
                "/tmp/snippet.jsonl",
                42_i64
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.search("delta", SearchFilters::default(), 5, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        // With contentless FTS5, snippet is generated from content via snippet_from_content()
        assert_eq!(hits[0].snippet, snippet_from_content(&hits[0].content));
        assert!(hits[0].snippet.contains("delta"));

        Ok(())
    }

    #[test]
    fn sqlite_backend_respects_source_filter() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('laptop', 'ssh')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/local')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(2, '/remote')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(1, 1, 1, '  local  ', NULL, 'local title', '/tmp/local.jsonl')",
        )?;
        conn.execute("INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(2, 1, 2, 'laptop', 'dev@laptop', 'remote title', '/tmp/remote.jsonl')")?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(1, 1, 0, 'auth token failure', 42)")?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(2, 2, 0, 'auth token failure', 43)")?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                1_i64,
                "auth token failure",
                "local title",
                "codex",
                "/local",
                "/tmp/local.jsonl",
                42_i64
            ],
        )?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                2_i64,
                "auth token failure",
                "remote title",
                "codex",
                "/remote",
                "/tmp/remote.jsonl",
                43_i64
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let local_hits = client.browse_by_date(
            SearchFilters {
                source_filter: SourceFilter::Local,
                ..SearchFilters::default()
            },
            5,
            0,
            true,
            FieldMask::FULL,
        )?;
        assert_eq!(local_hits.len(), 1);
        assert_eq!(local_hits[0].source_id, "local");

        let remote_hits = client.browse_by_date(
            SearchFilters {
                source_filter: SourceFilter::SourceId("  LOCAL  ".to_string()),
                ..SearchFilters::default()
            },
            5,
            0,
            true,
            FieldMask::FULL,
        )?;
        assert_eq!(remote_hits.len(), 1);
        assert_eq!(remote_hits[0].source_id, "local");
        assert_eq!(remote_hits[0].origin_kind, "local");

        Ok(())
    }

    #[test]
    fn sqlite_backend_remote_source_filter_matches_blank_source_id_with_origin_host() -> Result<()>
    {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, '   ', 'dev@laptop', 'remote title', '/tmp/remote-filter.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO messages(id, conversation_id, idx, content, created_at)
             VALUES(1, 1, 0, 'remote filter proof', 42)",
        )?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, NULL, ?5, ?6)",
            params![
                1_i64,
                "remote filter proof",
                "remote title",
                "codex",
                "/tmp/remote-filter.jsonl",
                42_i64
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let remote_hits = client.search(
            "remote",
            SearchFilters {
                source_filter: SourceFilter::Remote,
                ..Default::default()
            },
            5,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(remote_hits.len(), 1);
        assert_eq!(remote_hits[0].source_id, "dev@laptop");
        assert_eq!(remote_hits[0].origin_kind, "remote");
        assert_eq!(remote_hits[0].origin_host.as_deref(), Some("dev@laptop"));

        let source_hits = client.search(
            "remote",
            SearchFilters {
                source_filter: SourceFilter::SourceId("dev@laptop".into()),
                ..Default::default()
            },
            5,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(source_hits.len(), 1);
        assert_eq!(source_hits[0].source_id, "dev@laptop");
        assert_eq!(source_hits[0].origin_kind, "remote");

        Ok(())
    }

    #[test]
    fn sqlite_backend_workspace_filter_matches_null_workspace_as_empty_string() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                content='',
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/named')")?;
        // Conversation 1: no workspace (workspace_id=NULL)
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(1, 1, NULL, 'local', NULL, 'null workspace', '/tmp/null-workspace.jsonl')",
        )?;
        // Conversation 2: with workspace
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path) VALUES(2, 1, 1, 'local', NULL, 'named workspace', '/tmp/named-workspace.jsonl')",
        )?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(1, 1, 0, 'auth token failure', 42)")?;
        conn.execute("INSERT INTO messages(id, conversation_id, idx, content, created_at) VALUES(2, 2, 0, 'auth token failure', 43)")?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, NULL, ?5, ?6)",
            params![
                1_i64,
                "auth token failure",
                "null workspace",
                "codex",
                "/tmp/null-workspace.jsonl",
                42_i64
            ],
        )?;
        conn.execute_compat(
            "INSERT INTO fts_messages(rowid, content, title, agent, workspace, source_path, created_at)
             VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7)",
            params![
                2_i64,
                "auth token failure",
                "named workspace",
                "codex",
                "/named",
                "/tmp/named-workspace.jsonl",
                43_i64
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.search(
            "auth",
            SearchFilters {
                workspaces: HashSet::from_iter([String::new()]),
                ..SearchFilters::default()
            },
            5,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].workspace, "");
        assert_eq!(hits[0].source_path, "/tmp/null-workspace.jsonl");

        Ok(())
    }

    #[test]
    fn sqlite_message_scan_preserves_boolean_or_precedence() {
        let simple_or =
            SearchClient::sqlite_message_scan_query("alpha OR beta").expect("simple OR scan query");
        assert!(SearchClient::sqlite_message_scan_score("alpha", &simple_or) > 0.0);
        assert!(SearchClient::sqlite_message_scan_score("beta", &simple_or) > 0.0);
        assert_eq!(
            SearchClient::sqlite_message_scan_score("gamma", &simple_or),
            0.0
        );

        let and_then_or = SearchClient::sqlite_message_scan_query("alpha AND beta OR gamma")
            .expect("AND followed by OR scan query");
        assert!(
            SearchClient::sqlite_message_scan_score("alpha gamma", &and_then_or) > 0.0,
            "alpha AND (beta OR gamma) should accept the gamma branch"
        );
        assert_eq!(
            SearchClient::sqlite_message_scan_score("alpha", &and_then_or),
            0.0
        );
        assert_eq!(
            SearchClient::sqlite_message_scan_score("beta gamma", &and_then_or),
            0.0
        );

        let or_then_and = SearchClient::sqlite_message_scan_query("alpha OR beta AND gamma")
            .expect("OR followed by AND scan query");
        assert!(
            SearchClient::sqlite_message_scan_score("alpha gamma", &or_then_and) > 0.0,
            "(alpha OR beta) AND gamma should accept the alpha branch"
        );
        assert!(
            SearchClient::sqlite_message_scan_score("beta gamma", &or_then_and) > 0.0,
            "(alpha OR beta) AND gamma should accept the beta branch"
        );
        assert_eq!(
            SearchClient::sqlite_message_scan_score("alpha", &or_then_and),
            0.0
        );

        let binary_not =
            SearchClient::sqlite_message_scan_query("alpha NOT beta").expect("NOT scan query");
        assert!(SearchClient::sqlite_message_scan_score("alpha", &binary_not) > 0.0);
        assert_eq!(
            SearchClient::sqlite_message_scan_score("alpha beta", &binary_not),
            0.0
        );
    }

    #[test]
    fn browse_by_date_treats_null_workspace_and_source_as_local() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL);
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                content TEXT NOT NULL,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, NULL, NULL, 'browse title', '/tmp/browse.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO messages(id, conversation_id, idx, content, created_at)
             VALUES(1, 1, 0, 'browse auth token failure', 123)",
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.browse_by_date(
            SearchFilters {
                workspaces: HashSet::from_iter([String::new()]),
                source_filter: SourceFilter::Local,
                ..SearchFilters::default()
            },
            5,
            0,
            true,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].workspace, "");
        assert_eq!(hits[0].source_id, "local");
        assert_eq!(hits[0].origin_kind, "local");

        Ok(())
    }

    #[test]
    fn hydrate_semantic_hits_with_ids_snippet_only_uses_full_content_for_snippets_and_identity()
    -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL,
                started_at INTEGER
             );
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL);
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path, started_at)
             VALUES(1, 1, NULL, 'local', NULL, 'semantic title', '/tmp/semantic.jsonl', 100)",
        )?;
        let shared_prefix = "shared-prefix ".repeat(32);
        let first = format!("{shared_prefix}first unique semantic tail");
        let second = format!("{shared_prefix}second unique semantic tail");
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, ?2, 'assistant', ?3, ?4)",
            &[
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Integer(0),
                fsqlite_types::value::SqliteValue::Text(first.clone().into()),
                fsqlite_types::value::SqliteValue::Integer(101),
            ],
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, ?2, 'assistant', ?3, ?4)",
            &[
                fsqlite_types::value::SqliteValue::Integer(2),
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text(second.clone().into()),
                fsqlite_types::value::SqliteValue::Integer(102),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.hydrate_semantic_hits_with_ids(
            &[
                VectorSearchResult {
                    message_id: 1,
                    chunk_idx: 0,
                    score: 0.9,
                },
                VectorSearchResult {
                    message_id: 2,
                    chunk_idx: 0,
                    score: 0.8,
                },
            ],
            FieldMask::new(false, true, true, true),
        )?;
        assert_eq!(hits.len(), 2);
        assert!(hits.iter().all(|(_, hit)| hit.content.is_empty()));
        assert!(hits.iter().all(|(_, hit)| !hit.snippet.is_empty()));
        assert_ne!(hits[0].1.content_hash, hits[1].1.content_hash);

        Ok(())
    }

    #[test]
    fn hydrate_semantic_hits_with_ids_normalizes_trimmed_local_source_metadata() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL,
                started_at INTEGER
             );
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL);
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path, started_at)
             VALUES(1, 1, NULL, '  local  ', NULL, 'trimmed local semantic', '/tmp/trimmed-local-semantic.jsonl', 100)",
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 101)",
            &[
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text("trimmed local semantic body".into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.hydrate_semantic_hits_with_ids(
            &[VectorSearchResult {
                message_id: 1,
                chunk_idx: 0,
                score: 0.9,
            }],
            FieldMask::new(false, true, true, true),
        )?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].1.source_id, "local");
        assert_eq!(hits[0].1.origin_kind, "local");

        Ok(())
    }

    #[test]
    fn hydrate_semantic_hits_with_ids_preserves_remote_origin_without_source_row() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL,
                started_at INTEGER
             );
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL);
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path, started_at)
             VALUES(1, 1, NULL, 'laptop', 'dev@laptop', 'remote semantic', '/tmp/remote-semantic.jsonl', 100)",
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 101)",
            &[
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text("remote semantic body".into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.hydrate_semantic_hits_with_ids(
            &[VectorSearchResult {
                message_id: 1,
                chunk_idx: 0,
                score: 0.9,
            }],
            FieldMask::new(false, true, true, true),
        )?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].1.source_id, "laptop");
        assert_eq!(hits[0].1.origin_kind, "remote");
        assert_eq!(hits[0].1.origin_host.as_deref(), Some("dev@laptop"));

        Ok(())
    }

    #[test]
    fn resolve_semantic_doc_ids_for_hits_distinguishes_same_source_path_line_by_content_hash()
    -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, 'local', NULL, 'Shared Session', '/tmp/progressive-shared.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(2, 1, NULL, 'local', NULL, 'Shared Session', '/tmp/progressive-shared.jsonl')",
        )?;
        let first = "same prefix first tail".to_string();
        let second = "same prefix second tail".to_string();
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, ?2, 0, 'assistant', ?3, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(11),
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text(first.clone().into()),
            ],
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, ?2, 0, 'assistant', ?3, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(22),
                fsqlite_types::value::SqliteValue::Integer(2),
                fsqlite_types::value::SqliteValue::Text(second.clone().into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let first_hit = SearchHit {
            title: "Shared Session".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(
                &first,
                "/tmp/progressive-shared.jsonl",
                Some(1),
                Some(100),
            ),
            score: 0.0,
            source_path: "/tmp/progressive-shared.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let second_hit = SearchHit {
            title: "Shared Session".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(
                &second,
                "/tmp/progressive-shared.jsonl",
                Some(1),
                Some(100),
            ),
            score: 0.0,
            source_path: "/tmp/progressive-shared.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let resolved = client.resolve_semantic_doc_ids_for_hits(&[first_hit, second_hit])?;
        assert_eq!(resolved.len(), 2);
        assert_eq!(resolved[0].as_ref().map(|hit| hit.message_id), Some(11));
        assert_eq!(resolved[1].as_ref().map(|hit| hit.message_id), Some(22));
        assert_ne!(
            resolved[0].as_ref().map(|hit| hit.doc_id.as_str()),
            resolved[1].as_ref().map(|hit| hit.doc_id.as_str())
        );

        Ok(())
    }

    #[test]
    fn hydrate_semantic_hits_with_ids_keeps_missing_title_empty() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL,
                started_at INTEGER
             );
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL);
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path, started_at)
             VALUES(1, 1, NULL, 'local', NULL, NULL, '/tmp/untitled-semantic.jsonl', 100)",
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 101)",
            &[
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text("untitled semantic body".into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.hydrate_semantic_hits_with_ids(
            &[VectorSearchResult {
                message_id: 1,
                chunk_idx: 0,
                score: 0.9,
            }],
            FieldMask::new(false, true, true, true),
        )?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].1.title, "");

        Ok(())
    }

    #[test]
    fn resolve_semantic_doc_ids_for_hits_prefers_conversation_id_over_ambiguous_provenance()
    -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, 'local', NULL, 'Shared Session', '/tmp/progressive-conversation-id.jsonl')",
        )?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(2, 1, NULL, 'local', NULL, 'Shared Session', '/tmp/progressive-conversation-id.jsonl')",
        )?;
        let content = "same ambiguous content".to_string();
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, ?2, 0, 'assistant', ?3, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(11),
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text(content.clone().into()),
            ],
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, ?2, 0, 'assistant', ?3, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(22),
                fsqlite_types::value::SqliteValue::Integer(2),
                fsqlite_types::value::SqliteValue::Text(content.clone().into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let first_hit = SearchHit {
            title: "Shared Session".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(
                &content,
                "/tmp/progressive-conversation-id.jsonl",
                Some(1),
                Some(100),
            ),
            score: 0.0,
            source_path: "/tmp/progressive-conversation-id.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: Some(1),
        };
        let second_hit = SearchHit {
            conversation_id: Some(2),
            ..first_hit.clone()
        };

        let resolved = client.resolve_semantic_doc_ids_for_hits(&[first_hit, second_hit])?;
        assert_eq!(resolved.len(), 2);
        assert_eq!(resolved[0].as_ref().map(|hit| hit.message_id), Some(11));
        assert_eq!(resolved[1].as_ref().map(|hit| hit.message_id), Some(22));

        Ok(())
    }

    #[test]
    fn resolve_semantic_doc_ids_for_hits_treats_null_source_as_local() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, NULL, NULL, 'Legacy Local', '/tmp/legacy-local.jsonl')",
        )?;
        let content = "legacy local semantic message".to_string();
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(11),
                fsqlite_types::value::SqliteValue::Text(content.clone().into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "Legacy Local".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(&content, "/tmp/legacy-local.jsonl", Some(1), Some(100)),
            score: 0.0,
            source_path: "/tmp/legacy-local.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let resolved = client.resolve_semantic_doc_ids_for_hits(&[hit])?;
        assert_eq!(resolved.len(), 1);
        assert_eq!(resolved[0].as_ref().map(|hit| hit.message_id), Some(11));

        Ok(())
    }

    #[test]
    fn resolve_semantic_doc_ids_for_hits_matches_trimmed_local_source_id() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, '  local  ', NULL, 'Trimmed Local', '/tmp/trimmed-local.jsonl')",
        )?;
        let content = "trimmed local semantic message".to_string();
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(11),
                fsqlite_types::value::SqliteValue::Text(content.clone().into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "Trimmed Local".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(&content, "/tmp/trimmed-local.jsonl", Some(1), Some(100)),
            score: 0.0,
            source_path: "/tmp/trimmed-local.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let resolved = client.resolve_semantic_doc_ids_for_hits(&[hit])?;
        assert_eq!(resolved.len(), 1);
        assert_eq!(resolved[0].as_ref().map(|doc| doc.message_id), Some(11));

        Ok(())
    }

    #[test]
    fn resolve_semantic_doc_ids_for_hits_normalizes_blank_local_source_id() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, 'local', NULL, 'Blank Local', '/tmp/blank-local.jsonl')",
        )?;
        let content = "blank local semantic message".to_string();
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(11),
                fsqlite_types::value::SqliteValue::Text(content.clone().into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "Blank Local".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(&content, "/tmp/blank-local.jsonl", Some(1), Some(100)),
            score: 0.0,
            source_path: "/tmp/blank-local.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "   ".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let resolved = client.resolve_semantic_doc_ids_for_hits(&[hit])?;
        assert_eq!(resolved.len(), 1);
        assert_eq!(resolved[0].as_ref().map(|doc| doc.message_id), Some(11));

        Ok(())
    }

    #[test]
    fn resolve_semantic_doc_ids_for_hits_infers_remote_source_from_origin_host_when_source_id_blank()
    -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                role TEXT,
                content TEXT NOT NULL,
                created_at INTEGER
             );",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, '   ', 'dev@laptop', 'Legacy Remote', '/tmp/legacy-remote.jsonl')",
        )?;
        let content = "legacy remote semantic message".to_string();
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, role, content, created_at)
             VALUES(?1, 1, 0, 'assistant', ?2, 100)",
            &[
                fsqlite_types::value::SqliteValue::Integer(11),
                fsqlite_types::value::SqliteValue::Text(content.clone().into()),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "Legacy Remote".into(),
            snippet: String::new(),
            content: String::new(),
            content_hash: stable_hit_hash(&content, "/tmp/legacy-remote.jsonl", Some(1), Some(100)),
            score: 0.0,
            source_path: "/tmp/legacy-remote.jsonl".into(),
            agent: "codex".into(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "dev@laptop".into(),
            origin_kind: "remote".into(),
            origin_host: Some("dev@laptop".into()),
            conversation_id: None,
        };

        let resolved = client.resolve_semantic_doc_ids_for_hits(&[hit])?;
        assert_eq!(resolved.len(), 1);
        assert_eq!(resolved[0].as_ref().map(|doc| doc.message_id), Some(11));

        Ok(())
    }

    #[test]
    fn browse_by_date_snippet_only_uses_full_content_for_hit_identity() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER NOT NULL,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT NOT NULL
             );
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL);
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER NOT NULL,
                idx INTEGER,
                content TEXT NOT NULL,
                created_at INTEGER
             );
             CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);",
        )?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute(
            "INSERT INTO conversations(id, agent_id, workspace_id, source_id, origin_host, title, source_path)
             VALUES(1, 1, NULL, 'local', NULL, 'browse title', '/tmp/browse-shared.jsonl')",
        )?;
        let shared_prefix = "shared-prefix ".repeat(48);
        let first = format!("{shared_prefix}first browse-only tail");
        let second = format!("{shared_prefix}second browse-only tail");
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, content, created_at)
             VALUES(?1, 1, ?2, ?3, ?4)",
            &[
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Integer(0),
                fsqlite_types::value::SqliteValue::Text(first.clone().into()),
                fsqlite_types::value::SqliteValue::Integer(101),
            ],
        )?;
        conn.execute_with_params(
            "INSERT INTO messages(id, conversation_id, idx, content, created_at)
             VALUES(?1, 1, ?2, ?3, ?4)",
            &[
                fsqlite_types::value::SqliteValue::Integer(2),
                fsqlite_types::value::SqliteValue::Integer(1),
                fsqlite_types::value::SqliteValue::Text(second.clone().into()),
                fsqlite_types::value::SqliteValue::Integer(102),
            ],
        )?;

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.browse_by_date(
            SearchFilters::default(),
            10,
            0,
            true,
            FieldMask::new(false, true, true, true),
        )?;
        assert_eq!(hits.len(), 2);
        assert!(hits.iter().all(|hit| hit.content.is_empty()));
        assert!(hits.iter().all(|hit| !hit.snippet.is_empty()));
        assert_ne!(hits[0].content_hash, hits[1].content_hash);

        Ok(())
    }

    #[test]
    fn cache_invalidates_on_new_data() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // 1. Add initial doc
        let conv1 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("first".into()),
            workspace: None,
            source_path: dir.path().join("1.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "apple banana".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv1)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // 2. Search "app" -> should hit "apple"
        let hits = client.search("app", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].content, "apple banana");

        // 3. Verify it's cached (peek internal state)
        {
            let cache = client.prefix_cache.lock().unwrap();
            let shard = cache.shard_opt("global").unwrap();
            // "app" should be in cache
            assert!(shard.contains(&client.cache_key("app", &SearchFilters::default())));
        }

        // 4. Add new doc with "apricot"
        let conv2 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("second".into()),
            workspace: None,
            source_path: dir.path().join("2.jsonl"),
            started_at: Some(2),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(2),
                content: "apricot".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv2)?;
        index.commit()?;

        // 5. Force reload (mocking time passing or just ensuring reload triggers)
        // In test, maybe_reload_reader uses 300ms debounce.
        // We can rely on opstamp check logic which runs AFTER reload.
        // We need to sleep briefly to bypass debounce or just modify test to not rely on time?
        // Actually SearchClient::maybe_reload_reader checks duration.
        std::thread::sleep(std::time::Duration::from_millis(350));

        // 6. Search "ap" (prefix of apricot and apple)
        // The cache for "app" should be cleared if opstamp changed.
        let _hits = client.search("app", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        // Should now find 1 doc still ("apple"), but cache should have been cleared first

        // Search "apr" -> should find "apricot"
        let hits = client.search("apr", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].content, "apricot");

        // Check that cache was cleared by verifying a stale key is gone?
        // Or rely on correctness of results if we searched a common prefix?

        Ok(())
    }

    #[test]
    fn track_generation_clears_cache_on_change() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "hello world".into(),
            snippet: "hello".into(),
            content: "hello world".into(),
            content_hash: stable_content_hash("hello world"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let hits = vec![hit];

        client.put_cache("hello", &SearchFilters::default(), &hits);
        {
            let cache = client.prefix_cache.lock().unwrap();
            assert!(!cache.shards.is_empty());
        }

        client.track_generation(1);
        {
            let cache = client.prefix_cache.lock().unwrap();
            assert!(!cache.shards.is_empty());
        }

        client.track_generation(2);
        {
            let cache = client.prefix_cache.lock().unwrap();
            assert!(cache.shards.is_empty());
        }
    }

    #[test]
    fn cache_total_cap_evicts_across_shards() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(2, 0)), // tiny entry cap, no byte cap
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "a".into(),
            snippet: "a".into(),
            content: "a".into(),
            content_hash: stable_content_hash("a"),
            score: 1.0,
            source_path: "p".into(),
            agent: "agent1".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let hits = vec![hit.clone()];

        let mut filters = SearchFilters::default();
        filters.agents.insert("agent1".into());
        client.put_cache("a", &filters, &hits);
        filters.agents.clear();
        filters.agents.insert("agent2".into());
        client.put_cache("b", &filters, &hits);
        filters.agents.clear();
        filters.agents.insert("agent3".into());
        client.put_cache("c", &filters, &hits);

        let stats = client.cache_stats();
        assert!(stats.total_cost <= stats.total_cap);
        assert_eq!(stats.total_cap, 2);
    }

    #[test]
    fn cache_stats_reflect_metrics() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        client.metrics.inc_cache_hits();
        client.metrics.inc_cache_miss();
        client.metrics.inc_cache_shortfall();
        client.metrics.record_reload(Duration::from_millis(10));

        let stats = client.cache_stats();
        assert_eq!(stats.cache_hits, 1);
        assert_eq!(stats.cache_miss, 1);
        assert_eq!(stats.cache_shortfall, 1);
        assert_eq!(stats.reloads, 1);
        assert_eq!(stats.reload_ms_total, 10);
        assert_eq!(stats.total_cap, *CACHE_TOTAL_CAP);
        assert_eq!(stats.eviction_policy, "lru");
        assert_eq!(stats.prewarm_scheduled, 0);
        assert_eq!(stats.prewarm_skipped_pressure, 0);
        assert_eq!(CacheStats::default().eviction_policy, "unknown");
    }

    #[test]
    fn adaptive_query_prewarm_schedules_only_after_hot_prefix_cache_entry() {
        let (tx, rx) = mpsc::unbounded();
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(10, 0)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: Some(tx),
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };
        let mut filters = SearchFilters::default();
        filters.workspaces.insert("/tmp/cass-workspace".into());

        client.maybe_schedule_adaptive_query_prewarm("hel", &filters);
        assert!(
            rx.try_recv().is_err(),
            "cold prefixes should not schedule adaptive prewarm"
        );

        let mut hit = projected_minimal_fields_search_hit("hello title", "p");
        hit.snippet = "hello".into();
        hit.content = "hello world".into();
        hit.content_hash = stable_content_hash(&hit.content);
        client.put_cache("hel", &filters, std::slice::from_ref(&hit));

        let total_cost_before = client.cache_stats().total_cost;
        client.maybe_schedule_adaptive_query_prewarm("hel", &filters);
        assert!(
            rx.try_recv().is_err(),
            "an exact cached query should not schedule redundant prewarm"
        );
        client.maybe_schedule_adaptive_query_prewarm("hello", &filters);

        let job = rx
            .try_recv()
            .expect("hot prefix should schedule adaptive prewarm");
        assert_eq!(job.query, "hello");
        assert_eq!(job.shard_name, "workspace:/tmp/cass-workspace");
        assert_eq!(job.filters_fingerprint, filters_fingerprint(&filters));
        let stats = client.cache_stats();
        assert_eq!(stats.prewarm_scheduled, 1);
        assert_eq!(stats.prewarm_skipped_pressure, 0);
        assert_eq!(
            stats.total_cost, total_cost_before,
            "prewarm scheduling should not mutate result-cache contents"
        );
    }

    #[test]
    fn adaptive_query_prewarm_skips_when_cache_byte_cap_is_under_pressure() {
        let mut hit = projected_minimal_fields_search_hit("hello title", "p");
        hit.snippet = "hello".into();
        hit.content = "hello world with enough content to consume the small byte budget".into();
        hit.content_hash = stable_content_hash(&hit.content);
        let byte_cap = cached_hit_from(&hit).approx_bytes();

        let (tx, rx) = mpsc::unbounded();
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(10, byte_cap)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: Some(tx),
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };
        let filters = SearchFilters::default();

        client.put_cache("hel", &filters, std::slice::from_ref(&hit));
        client.maybe_schedule_adaptive_query_prewarm("zebra", &filters);
        assert_eq!(
            client.cache_stats().prewarm_skipped_pressure,
            0,
            "cold queries should not be counted as pressure-skipped prewarm jobs"
        );

        client.maybe_schedule_adaptive_query_prewarm("hello", &filters);

        assert!(
            rx.try_recv().is_err(),
            "prewarm should be disabled while cache byte pressure is high"
        );
        let stats = client.cache_stats();
        assert_eq!(stats.prewarm_scheduled, 0);
        assert_eq!(stats.prewarm_skipped_pressure, 1);
        assert!(stats.approx_bytes <= stats.byte_cap);
    }

    #[test]
    fn cache_eviction_count_tracks_evictions() {
        // tiny entry cap (2 entries), no byte cap - forces evictions
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(2, 0)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hit = SearchHit {
            title: "test".into(),
            snippet: "snippet".into(),
            content: "content".into(),
            content_hash: stable_content_hash("content"),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        // Put 3 entries - should trigger 1 eviction (cap is 2)
        client.put_cache(
            "query1",
            &SearchFilters::default(),
            std::slice::from_ref(&hit),
        );
        client.put_cache(
            "query2",
            &SearchFilters::default(),
            std::slice::from_ref(&hit),
        );
        client.put_cache(
            "query3",
            &SearchFilters::default(),
            std::slice::from_ref(&hit),
        );

        let stats = client.cache_stats();
        assert!(
            stats.eviction_count >= 1,
            "should have evicted at least 1 entry"
        );
        assert!(stats.total_cost <= 2, "should be at or below cap");
        assert!(stats.approx_bytes > 0, "should track bytes used");
    }

    #[test]
    fn default_cache_byte_cap_scales_with_available_memory() {
        let gib = 1024_u64 * 1024 * 1024;

        assert_eq!(
            default_cache_byte_cap_for_available(None),
            DEFAULT_CACHE_BYTE_CAP_FALLBACK
        );
        assert_eq!(
            default_cache_byte_cap_for_available(Some(2 * gib)),
            DEFAULT_CACHE_BYTE_CAP_FALLBACK,
            "small hosts keep a conservative cache byte budget"
        );
        assert_eq!(
            default_cache_byte_cap_for_available(Some(64 * gib)),
            512 * 1024 * 1024,
            "larger hosts get a proportionally larger cache byte budget"
        );
        assert_eq!(
            default_cache_byte_cap_for_available(Some(256 * gib)),
            usize::try_from(DEFAULT_CACHE_BYTE_CAP_CEILING).unwrap_or(usize::MAX),
            "large swarm hosts still have a bounded default cache budget"
        );
    }

    #[test]
    fn malformed_cache_byte_cap_env_uses_default_instead_of_disabling_guard() {
        let gib = 1024_u64 * 1024 * 1024;

        assert_eq!(cache_byte_cap_from_env_value(Some("0"), Some(64 * gib)), 0);
        assert_eq!(
            cache_byte_cap_from_env_value(Some("not-a-number"), Some(64 * gib)),
            default_cache_byte_cap_for_available(Some(64 * gib)),
            "malformed env should keep the default memory guard active"
        );
        assert_eq!(
            cache_byte_cap_from_env_value(None, Some(64 * gib)),
            default_cache_byte_cap_for_available(Some(64 * gib))
        );
    }

    #[test]
    fn cache_eviction_policy_env_defaults_to_lru_and_accepts_s3_fifo() {
        assert_eq!(
            cache_eviction_policy_from_env_value(None),
            CacheEvictionPolicy::Lru
        );
        assert_eq!(
            cache_eviction_policy_from_env_value(Some("not-a-policy")),
            CacheEvictionPolicy::Lru,
            "malformed env keeps the current LRU behavior"
        );
        assert_eq!(
            cache_eviction_policy_from_env_value(Some("s3-fifo")),
            CacheEvictionPolicy::S3Fifo
        );
        assert_eq!(
            cache_eviction_policy_from_env_value(Some("s3_fifo")),
            CacheEvictionPolicy::S3Fifo
        );
    }

    #[test]
    fn s3_fifo_admission_rejects_one_off_byte_heavy_entries_then_admits_ghost_replay() {
        let content = "large".repeat(1_000);
        let hit = SearchHit {
            title: "large".into(),
            snippet: "large".into(),
            content: content.clone(),
            content_hash: stable_content_hash(&content),
            score: 1.0,
            source_path: "large-path".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let cached = cached_hit_from(&hit);
        let byte_cap = cached.approx_bytes() + 1_024;
        assert!(
            cached.approx_bytes() > byte_cap.div_ceil(S3_FIFO_LARGE_ENTRY_FRACTION_DENOMINATOR)
        );

        let mut cache = CacheShards::new_with_policy(100, byte_cap, CacheEvictionPolicy::S3Fifo);
        let key = Arc::<str>::from("large-query");

        cache.put("global", key.clone(), vec![cached.clone()]);
        assert_eq!(
            cache.total_cost(),
            0,
            "first one-off large entry is not admitted"
        );
        assert_eq!(cache.ghost_entries(), 1);
        assert_eq!(cache.admission_rejects(), 1);

        cache.put("global", key, vec![cached]);
        assert_eq!(
            cache.total_cost(),
            1,
            "ghost replay admits the repeated query"
        );
        assert_eq!(cache.ghost_entries(), 0);
        assert!(cache.ghost_keys.is_empty());
        assert_eq!(cache.admission_rejects(), 1);
        assert!(cache.total_bytes() <= cache.byte_cap());
    }

    #[test]
    fn lru_policy_keeps_admitting_large_entries_under_existing_caps() {
        let content = "large".repeat(1_000);
        let hit = SearchHit {
            title: "large".into(),
            snippet: "large".into(),
            content: content.clone(),
            content_hash: stable_content_hash(&content),
            score: 1.0,
            source_path: "large-path".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let cached = cached_hit_from(&hit);
        let byte_cap = cached.approx_bytes() + 1_024;
        let mut cache = CacheShards::new_with_policy(100, byte_cap, CacheEvictionPolicy::Lru);

        cache.put("global", Arc::<str>::from("large-query"), vec![cached]);

        assert_eq!(cache.total_cost(), 1);
        assert_eq!(cache.ghost_entries(), 0);
        assert_eq!(cache.admission_rejects(), 0);
        assert_eq!(cache.policy_label(), "lru");
    }

    #[test]
    fn cache_byte_cap_triggers_eviction() {
        // Large entry cap (1000), tiny byte cap (100 bytes) - forces byte-based evictions
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(1000, 100)), // byte cap of 100
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        // Large content to exceed byte cap quickly
        let content = "c".repeat(100);
        let hit = SearchHit {
            title: "a".repeat(50),
            snippet: "b".repeat(50),
            content: content.clone(), // 200+ bytes per hit
            content_hash: stable_content_hash(&content),
            score: 1.0,
            source_path: "p".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        // Put 3 large entries - should trigger byte-based evictions
        client.put_cache("q1", &SearchFilters::default(), std::slice::from_ref(&hit));
        client.put_cache("q2", &SearchFilters::default(), std::slice::from_ref(&hit));
        client.put_cache("q3", &SearchFilters::default(), std::slice::from_ref(&hit));

        let stats = client.cache_stats();
        assert!(
            stats.eviction_count >= 1,
            "byte cap should trigger evictions"
        );
        assert_eq!(stats.byte_cap, 100, "byte cap should be reported");
        // Note: approx_bytes may briefly exceed cap during put, but eviction brings it down
    }

    #[test]
    fn cache_byte_pressure_evicts_byte_heavy_shard_before_small_entries() {
        let small_hit = SearchHit {
            title: "small".into(),
            snippet: "small".into(),
            content: "small".into(),
            content_hash: stable_content_hash("small"),
            score: 1.0,
            source_path: "small-path".into(),
            agent: "a".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let large_content = "large".repeat(2_000);
        let large_hit = SearchHit {
            title: "large".into(),
            snippet: "large".into(),
            content: large_content.clone(),
            content_hash: stable_content_hash(&large_content),
            score: 1.0,
            source_path: "large-path".into(),
            agent: "b".into(),
            workspace: "w".into(),
            workspace_original: None,
            created_at: None,
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        let mut cache = CacheShards::new(100, 1_024);
        cache.put(
            "small",
            Arc::<str>::from("small-1"),
            vec![cached_hit_from(&small_hit)],
        );
        cache.put(
            "small",
            Arc::<str>::from("small-2"),
            vec![cached_hit_from(&small_hit)],
        );
        cache.put(
            "large",
            Arc::<str>::from("large-1"),
            vec![cached_hit_from(&large_hit)],
        );

        assert_eq!(
            cache.shard_opt("small").map(LruCache::len),
            Some(2),
            "byte pressure should preserve the small shard"
        );
        assert!(
            cache.shard_opt("large").is_none_or(LruCache::is_empty),
            "oversized shard should be evicted first under byte pressure"
        );
        assert!(cache.total_bytes() <= cache.byte_cap());
    }

    // ============================================================
    // Phase 7 Tests: WildcardPattern, escape_regex, fallback, dedup
    // ============================================================

    #[test]
    fn wildcard_pattern_parse_exact() {
        // No wildcards - exact match
        assert_eq!(
            FsCassWildcardPattern::parse("hello"),
            FsCassWildcardPattern::Exact("hello".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("HELLO"),
            FsCassWildcardPattern::Exact("hello".into()) // lowercased
        );
        assert_eq!(
            FsCassWildcardPattern::parse("FooBar123"),
            FsCassWildcardPattern::Exact("foobar123".into())
        );
    }

    #[test]
    fn wildcard_pattern_parse_prefix() {
        // Trailing wildcard: foo*
        assert_eq!(
            FsCassWildcardPattern::parse("foo*"),
            FsCassWildcardPattern::Prefix("foo".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("CONFIG*"),
            FsCassWildcardPattern::Prefix("config".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("test*"),
            FsCassWildcardPattern::Prefix("test".into())
        );
    }

    #[test]
    fn wildcard_pattern_parse_suffix() {
        // Leading wildcard: *foo
        assert_eq!(
            FsCassWildcardPattern::parse("*foo"),
            FsCassWildcardPattern::Suffix("foo".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("*Error"),
            FsCassWildcardPattern::Suffix("error".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("*Handler"),
            FsCassWildcardPattern::Suffix("handler".into())
        );
    }

    #[test]
    fn wildcard_pattern_parse_substring() {
        // Both wildcards: *foo*
        assert_eq!(
            FsCassWildcardPattern::parse("*foo*"),
            FsCassWildcardPattern::Substring("foo".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("*CONFIG*"),
            FsCassWildcardPattern::Substring("config".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("*test*"),
            FsCassWildcardPattern::Substring("test".into())
        );
    }

    #[test]
    fn wildcard_pattern_parse_edge_cases() {
        // Empty after trimming wildcards
        assert_eq!(
            FsCassWildcardPattern::parse("*"),
            FsCassWildcardPattern::Exact(String::new())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("**"),
            FsCassWildcardPattern::Exact(String::new())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("***"),
            FsCassWildcardPattern::Exact(String::new())
        );

        // Single char with wildcards
        assert_eq!(
            FsCassWildcardPattern::parse("*a*"),
            FsCassWildcardPattern::Substring("a".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("a*"),
            FsCassWildcardPattern::Prefix("a".into())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("*a"),
            FsCassWildcardPattern::Suffix("a".into())
        );

        // Multiple asterisks get trimmed
        assert_eq!(
            FsCassWildcardPattern::parse("***foo***"),
            FsCassWildcardPattern::Substring("foo".into())
        );
    }

    #[test]
    fn wildcard_pattern_to_regex_suffix() {
        let pattern = FsCassWildcardPattern::Suffix("foo".into());
        // Suffix patterns need $ anchor to ensure "ends with" semantics
        assert_eq!(pattern.to_regex(), Some(".*foo$".into()));
    }

    #[test]
    fn wildcard_pattern_to_regex_substring() {
        let pattern = FsCassWildcardPattern::Substring("bar".into());
        assert_eq!(pattern.to_regex(), Some(".*bar.*".into()));
    }

    #[test]
    fn wildcard_pattern_to_regex_exact_prefix_none() {
        // Exact and Prefix patterns don't need regex
        let exact = FsCassWildcardPattern::Exact("foo".into());
        assert_eq!(exact.to_regex(), None);

        let prefix = FsCassWildcardPattern::Prefix("bar".into());
        assert_eq!(prefix.to_regex(), None);
    }

    #[test]
    fn match_type_quality_factors() {
        // Exact match has highest quality
        assert_eq!(MatchType::Exact.quality_factor(), 1.0);
        // Prefix is slightly lower
        assert_eq!(MatchType::Prefix.quality_factor(), 0.9);
        // Suffix is lower than prefix
        assert_eq!(MatchType::Suffix.quality_factor(), 0.8);
        // Substring is lower still
        assert_eq!(MatchType::Substring.quality_factor(), 0.7);
        // Implicit wildcard is lowest
        assert_eq!(MatchType::ImplicitWildcard.quality_factor(), 0.6);
    }

    #[test]
    fn dominant_match_type_single_terms() {
        // Single terms return their pattern's match type
        assert_eq!(dominant_match_type("hello"), MatchType::Exact);
        assert_eq!(dominant_match_type("hello*"), MatchType::Prefix);
        assert_eq!(dominant_match_type("*hello"), MatchType::Suffix);
        assert_eq!(dominant_match_type("*hello*"), MatchType::Substring);
    }

    #[test]
    fn dominant_match_type_multiple_terms() {
        // Multiple terms: returns the "loosest" (lowest quality factor)
        assert_eq!(dominant_match_type("foo bar"), MatchType::Exact);
        assert_eq!(dominant_match_type("foo bar*"), MatchType::Prefix);
        assert_eq!(dominant_match_type("foo *bar"), MatchType::Suffix);
        assert_eq!(dominant_match_type("foo* *bar*"), MatchType::Substring);
        // Substring is loosest even if other terms are exact
        assert_eq!(dominant_match_type("foo *bar* baz"), MatchType::Substring);
    }

    #[test]
    fn dominant_match_type_empty_query() {
        assert_eq!(dominant_match_type(""), MatchType::Exact);
        assert_eq!(dominant_match_type("   "), MatchType::Exact);
    }

    #[test]
    fn wildcard_pattern_to_regex_escapes_special_chars() {
        assert_eq!(
            FsCassWildcardPattern::Suffix("foo.bar".into()).to_regex(),
            Some(".*foo\\.bar$".into())
        );
        assert_eq!(
            FsCassWildcardPattern::Substring("a+b*c?".into()).to_regex(),
            Some(".*a\\+b\\*c\\?.*".into())
        );
    }

    #[test]
    fn wildcard_pattern_to_regex_escapes_complex_patterns() {
        assert_eq!(
            FsCassWildcardPattern::Suffix("test[0-9]+".into()).to_regex(),
            Some(".*test\\[0-9\\]\\+$".into())
        );
        assert_eq!(
            FsCassWildcardPattern::Substring("(a|b)".into()).to_regex(),
            Some(".*\\(a\\|b\\).*".into())
        );
        assert_eq!(
            FsCassWildcardPattern::Substring("end$".into()).to_regex(),
            Some(".*end\\$.*".into())
        );
        assert_eq!(
            FsCassWildcardPattern::Substring("^start".into()).to_regex(),
            Some(".*\\^start.*".into())
        );
    }

    #[test]
    fn is_tool_invocation_noise_detects_noise() {
        // "[Tool: Name]" is now kept (users search for tool usage)
        assert!(!is_tool_invocation_noise("[Tool: Bash]"));
        assert!(!is_tool_invocation_noise("[Tool: Read]"));

        // Empty tool names are noise
        assert!(is_tool_invocation_noise("[Tool:]"));
        assert!(is_tool_invocation_noise("[Tool: ]"));

        // Useful content should NOT be filtered
        assert!(!is_tool_invocation_noise("[Tool: Bash - Check status]"));
        assert!(!is_tool_invocation_noise("  [Tool: Grep - Search files]  "));

        // Very short tool markers (< 20 chars with "tool" prefix)
        assert!(is_tool_invocation_noise("[tool]"));
        assert!(is_tool_invocation_noise("tool: Bash"));
    }

    #[test]
    fn is_tool_invocation_noise_allows_useful_content() {
        // This should NOT be considered noise
        assert!(!is_tool_invocation_noise("[Tool: Read - src/main.rs]"));
        assert!(!is_tool_invocation_noise("[Tool: Bash - cargo test --lib]"));
    }

    #[test]
    fn is_tool_invocation_noise_detects_tool_markers() {
        // "[Tool: Name]" is now kept (searchable tool usage)
        assert!(!is_tool_invocation_noise("[Tool: Bash]"));
        assert!(!is_tool_invocation_noise("[Tool: Read]"));

        // Empty names are still noise
        assert!(is_tool_invocation_noise("[Tool:]"));

        // Useful content allowed
        assert!(!is_tool_invocation_noise("[Tool: Bash - Check status]"));
        assert!(!is_tool_invocation_noise("  [Tool: Write - description]  "));
    }

    #[test]
    fn deduplicate_hits_removes_exact_dupes() {
        let hits = vec![
            SearchHit {
                title: "title1".into(),
                snippet: "snip1".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 1.0,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title1".into(),
                snippet: "snip2".into(),
                content: "hello world".into(), // same content
                content_hash: stable_content_hash("hello world"),
                score: 0.5, // lower score
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(), // same source_id = will dedupe
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 1);
        assert_eq!(deduped[0].score, 1.0); // kept higher score
        assert_eq!(deduped[0].title, "title1");
    }

    #[test]
    fn deduplicate_hits_keeps_higher_score() {
        let hits = vec![
            SearchHit {
                title: "title1".into(),
                snippet: "snip1".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 0.3, // lower score first
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title1".into(),
                snippet: "snip2".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 0.9, // higher score second
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 1);
        assert_eq!(deduped[0].score, 0.9); // kept higher score
        assert_eq!(deduped[0].title, "title1");
    }

    #[test]
    fn deduplicate_hits_keeps_repeated_same_content_at_different_lines() {
        let first = SearchHit {
            title: "Shared Session".into(),
            snippet: String::new(),
            content: "repeat me".into(),
            content_hash: stable_content_hash("repeat me"),
            score: 10.0,
            source_path: "/shared/session.jsonl".into(),
            agent: "codex".into(),
            workspace: "/ws".into(),
            workspace_original: None,
            created_at: Some(100),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };
        let mut second = first.clone();
        second.line_number = Some(2);
        second.created_at = Some(200);
        second.score = 9.0;

        let deduped = deduplicate_hits(vec![first, second]);
        assert_eq!(deduped.len(), 2);
    }

    #[test]
    fn deduplicate_hits_keeps_distinct_conversation_ids_with_same_title_path_and_content() {
        let mut first = make_test_hit("same", 1.0);
        first.title = "Shared Session".into();
        first.source_path = "/shared/session.jsonl".into();
        first.content = "identical body".into();
        first.content_hash = stable_content_hash("identical body");
        first.conversation_id = Some(1);

        let mut second = first.clone();
        second.conversation_id = Some(2);
        second.score = 0.9;

        let deduped = deduplicate_hits(vec![first, second]);
        assert_eq!(deduped.len(), 2);
        assert!(deduped.iter().any(|hit| hit.conversation_id == Some(1)));
        assert!(deduped.iter().any(|hit| hit.conversation_id == Some(2)));
    }

    #[test]
    fn deduplicate_hits_coalesces_same_conversation_id_despite_title_drift() {
        let mut first = make_test_hit("same", 1.0);
        first.title = "Morning Session".into();
        first.source_path = "/shared/session.jsonl".into();
        first.content = "identical body".into();
        first.content_hash = stable_content_hash("identical body");
        first.conversation_id = Some(7);

        let mut second = first.clone();
        second.title = "Evening Session".into();
        second.score = 0.9;

        let deduped = deduplicate_hits(vec![first, second]);
        assert_eq!(deduped.len(), 1);
        assert_eq!(deduped[0].conversation_id, Some(7));
    }

    #[test]
    fn deduplicate_hits_keeps_distinct_titles_with_same_source_path_and_content() {
        let hits = vec![
            SearchHit {
                title: "Morning Session".into(),
                snippet: "snip1".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 0.9,
                source_path: "shared.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: None,
                line_number: Some(1),
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "Evening Session".into(),
                snippet: "snip2".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 0.8,
                source_path: "shared.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: None,
                line_number: Some(1),
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 2);
        assert!(deduped.iter().any(|hit| hit.title == "Morning Session"));
        assert!(deduped.iter().any(|hit| hit.title == "Evening Session"));
    }

    #[test]
    fn deduplicate_hits_normalizes_whitespace() {
        let hits = vec![
            SearchHit {
                title: "title1".into(),
                snippet: "snip1".into(),
                content: "hello    world".into(), // extra spaces
                content_hash: stable_content_hash("hello    world"),
                score: 1.0,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title1".into(),
                snippet: "snip2".into(),
                content: "hello world".into(), // normal spacing
                content_hash: stable_content_hash("hello world"),
                score: 0.5,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 1); // normalized to same content
    }

    #[test]
    fn deduplicate_hits_normalizes_blank_local_source_id() {
        let hits = vec![
            SearchHit {
                title: "title1".into(),
                snippet: "snip1".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 1.0,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title1".into(),
                snippet: "snip2".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 0.5,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "   ".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 1);
        assert_eq!(deduped[0].source_id, "local");
    }

    #[test]
    fn deduplicate_hits_filters_tool_noise() {
        let hits = vec![
            SearchHit {
                title: "title1".into(),
                snippet: "snip1".into(),
                content: "[Tool:]".into(), // noise (empty tool name)
                content_hash: stable_content_hash("[Tool:]"),
                score: 1.0,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title2".into(),
                snippet: "snip2".into(),
                content: "This is real content about testing".into(),
                content_hash: stable_content_hash("This is real content about testing"),
                score: 0.5,
                source_path: "b.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(200),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 1);
        assert!(deduped[0].content.contains("real content"));
    }

    #[test]
    fn deduplicate_hits_filters_acknowledgement_noise() {
        let hits = vec![
            SearchHit {
                title: "ack".into(),
                snippet: "ack".into(),
                content: "Acknowledged.".into(),
                content_hash: stable_content_hash("Acknowledged."),
                score: 1.0,
                source_path: "ack.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "real".into(),
                snippet: "real".into(),
                content: "Authentication refresh logic changed".into(),
                content_hash: stable_content_hash("Authentication refresh logic changed"),
                score: 0.5,
                source_path: "real.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(200),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits_with_query(hits, "authentication");
        assert_eq!(deduped.len(), 1);
        assert_eq!(deduped[0].title, "real");
    }

    #[test]
    fn deduplicate_hits_hides_system_prompts_unless_query_requests_them() {
        let prompt_hit = SearchHit {
            title: "prompt".into(),
            snippet: "prompt".into(),
            content:
                "# AGENTS.md instructions for /repo\n\nYou are a coding assistant. Follow the instructions exactly."
                    .into(),
            content_hash: stable_content_hash(
                "# AGENTS.md instructions for /repo\n\nYou are a coding assistant. Follow the instructions exactly.",
            ),
            score: 1.0,
            source_path: "prompt.jsonl".into(),
            agent: "agent".into(),
            workspace: "ws".into(),
            workspace_original: None,
            created_at: Some(100),
            line_number: None,
            match_type: MatchType::Exact,
            source_id: "local".into(),
            origin_kind: "local".into(),
            origin_host: None,
            conversation_id: None,
        };

        assert!(
            deduplicate_hits_with_query(vec![prompt_hit.clone()], "coding assistant").is_empty()
        );

        let kept = deduplicate_hits_with_query(vec![prompt_hit], "AGENTS.md instructions");
        assert_eq!(kept.len(), 1);
        assert_eq!(kept[0].title, "prompt");
    }

    #[test]
    fn deduplicate_hits_preserves_unique_content() {
        let hits = vec![
            SearchHit {
                title: "title1".into(),
                snippet: "snip1".into(),
                content: "first message".into(),
                content_hash: stable_content_hash("first message"),
                score: 1.0,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title2".into(),
                snippet: "snip2".into(),
                content: "second message".into(),
                content_hash: stable_content_hash("second message"),
                score: 0.8,
                source_path: "b.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(200),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "title3".into(),
                snippet: "snip3".into(),
                content: "third message".into(),
                content_hash: stable_content_hash("third message"),
                score: 0.6,
                source_path: "c.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(300),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(deduped.len(), 3); // all unique
    }

    /// P2.3: Deduplication respects source boundaries - same content from different sources
    /// should appear as separate results.
    #[test]
    fn deduplicate_hits_respects_source_boundaries() {
        let hits = vec![
            SearchHit {
                title: "local title".into(),
                snippet: "snip".into(),
                content: "hello world".into(),
                content_hash: stable_content_hash("hello world"),
                score: 1.0,
                source_path: "a.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(100),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "local".into(),
                origin_kind: "local".into(),
                origin_host: None,
                conversation_id: None,
            },
            SearchHit {
                title: "remote title".into(),
                snippet: "snip".into(),
                content: "hello world".into(), // same content
                content_hash: stable_content_hash("hello world"),
                score: 0.9,
                source_path: "b.jsonl".into(),
                agent: "agent".into(),
                workspace: "ws".into(),
                workspace_original: None,
                created_at: Some(200),
                line_number: None,
                match_type: MatchType::Exact,
                source_id: "work-laptop".into(), // different source = no dedupe
                origin_kind: "ssh".into(),
                origin_host: Some("work-laptop.local".into()),
                conversation_id: None,
            },
        ];

        let deduped = deduplicate_hits(hits);
        assert_eq!(
            deduped.len(),
            2,
            "same content from different sources should not dedupe"
        );
        assert!(deduped.iter().any(|h| h.source_id == "local"));
        assert!(deduped.iter().any(|h| h.source_id == "work-laptop"));
    }

    #[test]
    fn wildcard_fallback_sparse_check_uses_effective_limit() {
        assert!(
            !should_try_wildcard_fallback(1, 1, 0, 3),
            "a filled one-result page is not sparse for fallback purposes"
        );
        assert!(
            !should_try_wildcard_fallback(2, 2, 0, 3),
            "a filled two-result page is not sparse for fallback purposes"
        );
        assert!(
            should_try_wildcard_fallback(0, 1, 0, 3),
            "zero hits should still trigger fallback even for tiny pages"
        );
        assert!(
            should_try_wildcard_fallback(1, 2, 0, 3),
            "a partially filled page should still trigger fallback"
        );
        assert!(
            !should_try_wildcard_fallback(0, 5, 10, 3),
            "pagination should not trigger wildcard fallback"
        );
        assert!(
            should_try_wildcard_fallback(1, 0, 0, 3),
            "limit zero preserves the legacy sparse-threshold semantics"
        );
    }

    #[test]
    fn snippet_preview_fast_path_requires_snippet_only_match() {
        let snippet_only = FieldMask::new(false, true, false, false);
        let snippet = snippet_from_preview_without_full_content(
            snippet_only,
            "migration checks the database constraint before writing",
            "database",
        )
        .expect("preview should satisfy a snippet-only request when it contains the query");
        assert!(snippet.contains("**database**"));

        assert!(
            snippet_from_preview_without_full_content(
                FieldMask::FULL,
                "migration checks the database constraint before writing",
                "database",
            )
            .is_none(),
            "full-content requests must keep the sqlite hydration path"
        );
        assert!(
            snippet_from_preview_without_full_content(
                snippet_only,
                "migration checks constraints before writing",
                "database",
            )
            .is_none(),
            "snippet-only requests hydrate when the preview cannot show the match"
        );
    }

    #[test]
    fn search_with_fallback_returns_exact_when_sufficient() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Add enough docs to exceed threshold - each with UNIQUE content to avoid dedup
        for i in 0..5 {
            let conv = NormalizedConversation {
                agent_slug: "codex".into(),
                external_id: None,
                title: Some(format!("doc-{i}")),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: dir.path().join(format!("{i}.jsonl")),
                started_at: Some(100 + i),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100 + i),
                    // Each doc has unique content but shares "apple" keyword
                    content: format!("apple fruit number {i} is delicious and healthy"),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Search with low threshold - should not trigger fallback
        let result = client.search_with_fallback(
            "apple",
            SearchFilters::default(),
            10,
            0,
            3, // threshold of 3
            FieldMask::FULL,
        )?;

        assert!(!result.wildcard_fallback);
        assert!(result.hits.len() >= 3); // has enough results

        Ok(())
    }

    #[test]
    fn search_with_fallback_triggers_on_sparse_results() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Add docs with substring that won't match exact prefix
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("substring test".into()),
            workspace: Some(std::path::PathBuf::from("/ws")),
            source_path: dir.path().join("test.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "configuration management system".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Search for "config" which should match "configuration" via prefix
        let result = client.search_with_fallback(
            "config",
            SearchFilters::default(),
            10,
            0,
            5, // high threshold
            FieldMask::FULL,
        )?;

        // Since we have only 1 result and threshold is 5, it may trigger fallback
        // but *config* would still match "configuration"
        assert!(!result.hits.is_empty());

        Ok(())
    }

    #[test]
    fn search_with_fallback_skips_when_query_has_wildcards() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("test".into()),
            workspace: None,
            source_path: dir.path().join("test.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "testing data".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Query already has wildcards - should not trigger fallback
        let result = client.search_with_fallback(
            "*test*",
            SearchFilters::default(),
            10,
            0,
            10, // high threshold
            FieldMask::FULL,
        )?;

        assert!(!result.wildcard_fallback); // shouldn't trigger fallback for wildcard queries
        Ok(())
    }

    #[test]
    fn search_with_fallback_prefers_wildcards_when_they_add_hits() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // None of these documents contain the exact token "bet",
        // but they do contain it as a substring ("alphabet").
        for (i, body) in [
            "alphabet soup for coders",
            "mapping the alphabet city blocks",
        ]
        .iter()
        .enumerate()
        {
            let conv = NormalizedConversation {
                agent_slug: "codex".into(),
                external_id: None,
                title: Some(format!("alpha-{i}")),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: dir.path().join(format!("alpha-{i}.jsonl")),
                started_at: Some(100 + i as i64),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100 + i as i64),
                    content: body.to_string(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        let result = client.search_with_fallback(
            "bet",
            SearchFilters::default(),
            10,
            0,
            2,
            FieldMask::FULL,
        )?;

        assert!(
            result.wildcard_fallback,
            "should switch to wildcard fallback when it yields more hits"
        );
        assert_eq!(
            result.hits.len(),
            2,
            "fallback should surface all alphabet docs"
        );
        assert!(
            result
                .hits
                .iter()
                .all(|h| h.match_type == MatchType::ImplicitWildcard)
        );
        assert!(result.hits.iter().all(|h| h.content.contains("alphabet")));

        Ok(())
    }

    #[test]
    fn automatic_wildcard_fallback_skips_long_zero_hit_token() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("fruit".into()),
            workspace: Some(std::path::PathBuf::from("/ws")),
            source_path: dir.path().join("fruit.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "apple pear banana".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        let result = client.search_with_fallback(
            "zzzzzzunlikelyterm",
            SearchFilters::default(),
            10,
            0,
            1,
            FieldMask::FULL,
        )?;
        assert!(result.hits.is_empty());
        assert!(!result.wildcard_fallback);
        assert!(
            result
                .suggestions
                .iter()
                .any(|s| matches!(s.kind, SuggestionKind::WildcardQuery)),
            "manual wildcard suggestion should remain available"
        );

        let short_result = client.search_with_fallback(
            "pple",
            SearchFilters::default(),
            10,
            0,
            1,
            FieldMask::FULL,
        )?;
        assert!(short_result.wildcard_fallback);
        assert_eq!(short_result.hits.len(), 1);
        assert_eq!(short_result.hits[0].match_type, MatchType::ImplicitWildcard);

        Ok(())
    }

    #[test]
    fn nohit_suggestions_do_not_lazy_open_sqlite_when_tantivy_is_present() -> Result<()> {
        let dir = TempDir::new()?;
        let index_path = dir.path().join("index");
        let db_path = dir.path().join("cass.db");

        let storage = FrankenStorage::open(&db_path)?;
        storage.close()?;

        let mut index = TantivyIndex::open_or_create(&index_path)?;
        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("fruit".into()),
            workspace: Some(std::path::PathBuf::from("/ws")),
            source_path: dir.path().join("fruit.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "apple pear banana".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(&index_path, Some(&db_path))?.expect("index present");
        assert!(
            client
                .sqlite
                .lock()
                .map(|guard| guard.is_none())
                .unwrap_or(false),
            "sqlite should start closed"
        );

        let result = client.search_with_fallback(
            "zzzzzzunlikelyterm",
            SearchFilters::default(),
            10,
            0,
            1,
            FieldMask::FULL,
        )?;

        assert!(result.hits.is_empty());
        assert!(
            result
                .suggestions
                .iter()
                .any(|s| matches!(s.kind, SuggestionKind::WildcardQuery)),
            "manual wildcard suggestion should remain available"
        );
        assert!(
            result
                .suggestions
                .iter()
                .all(|s| !matches!(s.kind, SuggestionKind::AlternateAgent)),
            "alternate-agent suggestions should not force a SQLite open"
        );
        assert!(
            client
                .sqlite
                .lock()
                .map(|guard| guard.is_none())
                .unwrap_or(false),
            "sqlite should stay closed after Tantivy no-hit suggestions"
        );

        Ok(())
    }

    #[test]
    fn search_with_fallback_emits_wildcard_suggestion_on_zero_hits() -> Result<()> {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: "vtest|schema:none".into(),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let result = client.search_with_fallback(
            "ghost",
            SearchFilters::default(),
            5,
            0,
            3,
            FieldMask::FULL,
        )?;

        assert!(
            result.hits.is_empty(),
            "no index/db means no hits should be returned"
        );
        assert!(
            !result.wildcard_fallback,
            "with zero baseline and fallback hits, we should keep baseline and mark fallback=false"
        );

        let wildcard = result
            .suggestions
            .iter()
            .find(|s| matches!(s.kind, SuggestionKind::WildcardQuery))
            .expect("should suggest adding wildcards");
        assert_eq!(wildcard.suggested_query.as_deref(), Some("*ghost*"));

        Ok(())
    }

    #[test]
    fn search_with_fallback_skips_empty_query() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("test".into()),
            workspace: None,
            source_path: dir.path().join("test.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "testing data".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Empty query - should not trigger fallback
        let result = client.search_with_fallback(
            "  ",
            SearchFilters::default(),
            10,
            0,
            10,
            FieldMask::FULL,
        )?;

        assert!(!result.wildcard_fallback);
        Ok(())
    }

    #[test]
    fn search_with_fallback_skips_for_nonzero_offset() -> Result<()> {
        // Even with zero hits, fallback should not run when paginating (offset > 0)
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: "vtest|schema:none".into(),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let result = client.search_with_fallback(
            "ghost",
            SearchFilters::default(),
            5,
            10,
            3,
            FieldMask::FULL,
        )?;

        assert!(
            !result.wildcard_fallback,
            "fallback should not run on paginated searches"
        );
        // Suggestions still surface (wildcard suggestion expected)
        let wildcard = result
            .suggestions
            .iter()
            .find(|s| matches!(s.kind, SuggestionKind::WildcardQuery))
            .expect("wildcard suggestion present");
        assert_eq!(wildcard.suggested_query.as_deref(), Some("*ghost*"));

        Ok(())
    }

    #[test]
    fn generate_suggestions_limits_and_sets_shortcuts() -> Result<()> {
        // Build a client without backends; suggestions are purely local heuristics
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: "vtest|schema:none".into(),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".into()); // triggers remove-agent suggestion

        let result = client.search_with_fallback("claud", filters, 5, 0, 3, FieldMask::FULL)?;

        // Should cap at 3 suggestions with shortcuts 1..=3
        assert_eq!(
            result.suggestions.len(),
            3,
            "should truncate to 3 suggestions"
        );
        for (idx, sugg) in result.suggestions.iter().enumerate() {
            assert_eq!(
                sugg.shortcut,
                Some((idx + 1) as u8),
                "shortcut should match position (1-based)"
            );
        }

        // Expect wildcard, remove filter, and spelling fix (claud -> claude)
        assert!(
            result
                .suggestions
                .iter()
                .any(|s| matches!(s.kind, SuggestionKind::WildcardQuery)),
            "should suggest wildcard search"
        );
        assert!(
            result
                .suggestions
                .iter()
                .any(|s| matches!(s.kind, SuggestionKind::RemoveFilter)),
            "should suggest removing agent filter"
        );
        assert!(
            result
                .suggestions
                .iter()
                .any(|s| matches!(s.kind, SuggestionKind::SpellingFix)),
            "should suggest spelling fix for nearby agent name"
        );

        Ok(())
    }

    #[test]
    fn generate_suggestions_includes_recent_alternate_agents() -> Result<()> {
        let dir = TempDir::new()?;
        let db_path = dir.path().join("cass.db");
        let storage = FrankenStorage::open(&db_path)?;
        let workspace_id = storage.ensure_workspace(dir.path(), None)?;
        let base_ts = 1_700_000_010_000_i64;

        for (idx, slug) in ["claude_code", "codex"].iter().enumerate() {
            let agent = Agent {
                id: None,
                slug: (*slug).to_string(),
                name: (*slug).to_string(),
                version: None,
                kind: AgentKind::Cli,
            };
            let agent_id = storage.ensure_agent(&agent)?;
            let conversation = Conversation {
                id: None,
                agent_slug: (*slug).to_string(),
                workspace: Some(dir.path().to_path_buf()),
                external_id: Some(format!("alt-agent-{idx}")),
                title: Some(format!("alternate agent {idx}")),
                source_path: dir.path().join(format!("{slug}.jsonl")),
                started_at: Some(base_ts + idx as i64),
                ended_at: Some(base_ts + idx as i64),
                approx_tokens: Some(8),
                metadata_json: json!({}),
                messages: vec![Message {
                    id: None,
                    idx: 0,
                    role: MessageRole::User,
                    author: Some("user".into()),
                    created_at: Some(base_ts + idx as i64),
                    content: format!("content from {slug}"),
                    extra_json: json!({}),
                    snippets: Vec::new(),
                }],
                source_id: crate::sources::provenance::LOCAL_SOURCE_ID.to_string(),
                origin_host: None,
            };
            storage.insert_conversation_tree(agent_id, Some(workspace_id), &conversation)?;
        }
        drop(storage);

        let client = SearchClient::open(dir.path(), Some(&db_path))?.expect("db-backed client");
        let result = client.search_with_fallback(
            "ghost",
            SearchFilters::default(),
            5,
            0,
            3,
            FieldMask::FULL,
        )?;

        let alternate_agents: HashSet<String> = result
            .suggestions
            .iter()
            .filter(|suggestion| matches!(suggestion.kind, SuggestionKind::AlternateAgent))
            .filter_map(|suggestion| suggestion.suggested_filters.as_ref())
            .flat_map(|filters| filters.agents.iter().cloned())
            .collect();

        assert!(
            alternate_agents.contains("claude_code"),
            "should suggest claude_code from normalized conversations schema"
        );
        assert!(
            alternate_agents.contains("codex"),
            "should suggest codex from normalized conversations schema"
        );

        Ok(())
    }

    #[test]
    fn sanitize_query_preserves_wildcards() {
        // Wildcards should be preserved
        assert_eq!(fs_cass_sanitize_query("*foo*"), "*foo*");
        assert_eq!(fs_cass_sanitize_query("foo*"), "foo*");
        assert_eq!(fs_cass_sanitize_query("*bar"), "*bar");
        assert_eq!(fs_cass_sanitize_query("*config*"), "*config*");
    }

    #[test]
    fn sanitize_query_strips_other_special_chars() {
        // Non-wildcard special chars become spaces
        assert_eq!(fs_cass_sanitize_query("foo.bar"), "foo bar");
        assert_eq!(fs_cass_sanitize_query("c++"), "c  ");
        assert_eq!(fs_cass_sanitize_query("foo-bar"), "foo-bar");
        assert_eq!(fs_cass_sanitize_query("test_case"), "test case");
    }

    #[test]
    fn sanitize_query_combined() {
        // Mix of wildcards and special chars
        assert_eq!(fs_cass_sanitize_query("*foo.bar*"), "*foo bar*");
        assert_eq!(fs_cass_sanitize_query("test-*"), "test-*");
        assert_eq!(fs_cass_sanitize_query("*c++*"), "*c  *");
    }

    // Boolean query parsing tests
    #[test]
    fn parse_boolean_query_simple_terms() {
        let tokens = fs_cass_parse_boolean_query("foo bar baz");
        assert_eq!(tokens.len(), 3);
        assert_eq!(tokens[0], FsCassQueryToken::Term("foo".to_string()));
        assert_eq!(tokens[1], FsCassQueryToken::Term("bar".to_string()));
        assert_eq!(tokens[2], FsCassQueryToken::Term("baz".to_string()));
    }

    #[test]
    fn parse_boolean_query_and_operator() {
        let tokens = fs_cass_parse_boolean_query("foo AND bar");
        assert_eq!(tokens.len(), 3);
        assert_eq!(tokens[0], FsCassQueryToken::Term("foo".to_string()));
        assert_eq!(tokens[1], FsCassQueryToken::And);
        assert_eq!(tokens[2], FsCassQueryToken::Term("bar".to_string()));

        // Also test && syntax
        let tokens2 = fs_cass_parse_boolean_query("foo && bar");
        assert_eq!(tokens2.len(), 3);
        assert_eq!(tokens2[1], FsCassQueryToken::And);
    }

    #[test]
    fn parse_boolean_query_or_operator() {
        let tokens = fs_cass_parse_boolean_query("foo OR bar");
        assert_eq!(tokens.len(), 3);
        assert_eq!(tokens[0], FsCassQueryToken::Term("foo".to_string()));
        assert_eq!(tokens[1], FsCassQueryToken::Or);
        assert_eq!(tokens[2], FsCassQueryToken::Term("bar".to_string()));

        // Also test || syntax
        let tokens2 = fs_cass_parse_boolean_query("foo || bar");
        assert_eq!(tokens2.len(), 3);
        assert_eq!(tokens2[1], FsCassQueryToken::Or);
    }

    #[test]
    fn parse_boolean_query_not_operator() {
        let tokens = fs_cass_parse_boolean_query("foo NOT bar");
        assert_eq!(tokens.len(), 3);
        assert_eq!(tokens[0], FsCassQueryToken::Term("foo".to_string()));
        assert_eq!(tokens[1], FsCassQueryToken::Not);
        assert_eq!(tokens[2], FsCassQueryToken::Term("bar".to_string()));
    }

    #[test]
    fn parse_boolean_query_quoted_phrase() {
        let tokens = fs_cass_parse_boolean_query(r#"foo "exact phrase" bar"#);
        assert_eq!(tokens.len(), 3);
        assert_eq!(tokens[0], FsCassQueryToken::Term("foo".to_string()));
        assert_eq!(
            tokens[1],
            FsCassQueryToken::Phrase("exact phrase".to_string())
        );
        assert_eq!(tokens[2], FsCassQueryToken::Term("bar".to_string()));
    }

    #[test]
    fn parse_boolean_query_complex() {
        let tokens = fs_cass_parse_boolean_query(r#"error OR warning NOT "false positive""#);
        assert_eq!(tokens.len(), 5);
        assert_eq!(tokens[0], FsCassQueryToken::Term("error".to_string()));
        assert_eq!(tokens[1], FsCassQueryToken::Or);
        assert_eq!(tokens[2], FsCassQueryToken::Term("warning".to_string()));
        assert_eq!(tokens[3], FsCassQueryToken::Not);
        assert_eq!(
            tokens[4],
            FsCassQueryToken::Phrase("false positive".to_string())
        );
    }

    #[test]
    fn has_boolean_operators_detection() {
        assert!(!fs_cass_has_boolean_operators("foo bar"));
        assert!(fs_cass_has_boolean_operators("foo AND bar"));
        assert!(fs_cass_has_boolean_operators("foo OR bar"));
        assert!(fs_cass_has_boolean_operators("foo NOT bar"));
        assert!(fs_cass_has_boolean_operators(r#""exact phrase""#));
        assert!(fs_cass_has_boolean_operators("foo && bar"));
        assert!(fs_cass_has_boolean_operators("foo || bar"));
    }

    #[test]
    fn parse_boolean_query_case_insensitive_operators() {
        // Operators should be case-insensitive
        let tokens = fs_cass_parse_boolean_query("foo and bar or baz not qux");
        assert_eq!(tokens.len(), 7);
        assert_eq!(tokens[1], FsCassQueryToken::And);
        assert_eq!(tokens[3], FsCassQueryToken::Or);
        assert_eq!(tokens[5], FsCassQueryToken::Not);
    }

    #[test]
    fn parse_boolean_query_with_wildcards() {
        let tokens = fs_cass_parse_boolean_query("*config* OR env*");
        assert_eq!(tokens.len(), 3);
        assert_eq!(tokens[0], FsCassQueryToken::Term("*config*".to_string()));
        assert_eq!(tokens[1], FsCassQueryToken::Or);
        assert_eq!(tokens[2], FsCassQueryToken::Term("env*".to_string()));
    }

    // ============================================================
    // Filter Fidelity Property Tests (glt.9)
    // Verify filters are never violated in search results
    // ============================================================

    #[test]
    fn tantivy_search_hydrates_long_content_when_content_field_is_not_stored() -> Result<()> {
        let dir = TempDir::new()?;
        let db_path = dir.path().join("cass.db");
        let storage = FrankenStorage::open(&db_path)?;
        let workspace_id = storage.ensure_workspace(dir.path(), None)?;
        let agent = Agent {
            id: None,
            slug: "codex".into(),
            name: "Codex".into(),
            version: None,
            kind: AgentKind::Cli,
        };
        let agent_id = storage.ensure_agent(&agent)?;
        let long_content = format!(
            "{}needle appears past the preview boundary for hydration proof",
            "padding ".repeat(70)
        );
        let short_content = "shortneedle fits entirely inside the stored preview".to_string();
        let conversation = Conversation {
            id: None,
            agent_slug: "codex".into(),
            workspace: Some(dir.path().to_path_buf()),
            external_id: Some("hydrate-long-content".into()),
            title: Some("hydrated lexical doc".into()),
            source_path: dir.path().join("hydrate.jsonl"),
            started_at: Some(1_700_000_123_000),
            ended_at: Some(1_700_000_123_000),
            approx_tokens: Some(32),
            metadata_json: json!({}),
            messages: vec![
                Message {
                    id: None,
                    idx: 0,
                    role: MessageRole::User,
                    author: Some("user".into()),
                    created_at: Some(1_700_000_123_000),
                    content: long_content.clone(),
                    extra_json: json!({}),
                    snippets: Vec::new(),
                },
                Message {
                    id: None,
                    idx: 1,
                    role: MessageRole::Agent,
                    author: Some("assistant".into()),
                    created_at: Some(1_700_000_124_000),
                    content: short_content.clone(),
                    extra_json: json!({}),
                    snippets: Vec::new(),
                },
            ],
            source_id: crate::sources::provenance::LOCAL_SOURCE_ID.to_string(),
            origin_host: None,
        };
        storage.insert_conversation_tree(agent_id, Some(workspace_id), &conversation)?;
        storage.close()?;

        let index_path = dir.path().join("search-index");
        let mut index = TantivyIndex::open_or_create(&index_path)?;
        let normalized = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: Some("hydrate-long-content".into()),
            title: Some("hydrated lexical doc".into()),
            workspace: Some(dir.path().to_path_buf()),
            source_path: dir.path().join("hydrate.jsonl"),
            started_at: Some(1_700_000_123_000),
            ended_at: Some(1_700_000_123_000),
            metadata: json!({}),
            messages: vec![
                NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: Some("user".into()),
                    created_at: Some(1_700_000_123_000),
                    content: long_content.clone(),
                    extra: json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                },
                NormalizedMessage {
                    idx: 1,
                    role: "assistant".into(),
                    author: Some("assistant".into()),
                    created_at: Some(1_700_000_124_000),
                    content: short_content.clone(),
                    extra: json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                },
            ],
        };
        index.add_conversation(&normalized)?;
        index.commit()?;

        let client = SearchClient::open(&index_path, Some(&db_path))?.expect("db-backed client");
        let hits = client.search("needle", SearchFilters::default(), 5, 0, FieldMask::FULL)?;

        assert_eq!(hits.len(), 1, "expected one lexical hit");
        assert_eq!(hits[0].title, "hydrated lexical doc");
        assert!(
            hits[0]
                .content
                .contains("needle appears past the preview boundary"),
            "lexical hit should hydrate full content from sqlite when Tantivy content is not stored"
        );
        assert!(
            hits[0].snippet.to_lowercase().contains("needle"),
            "snippet should still be rendered from hydrated content"
        );

        let bounded_hits = client.search(
            "needle",
            SearchFilters::default(),
            5,
            0,
            FieldMask::FULL.with_preview_content_limit(Some(200)),
        )?;

        assert_eq!(bounded_hits.len(), 1, "expected one lexical hit");
        assert!(
            bounded_hits[0].content.starts_with("padding padding"),
            "bounded content may be served from the stored preview prefix"
        );
        assert!(
            !bounded_hits[0]
                .content
                .contains("needle appears past the preview boundary"),
            "bounded preview content should not hydrate the full sqlite row"
        );

        let short_client =
            SearchClient::open(&index_path, Some(&db_path))?.expect("db-backed client");
        assert!(
            short_client
                .sqlite
                .lock()
                .map(|guard| guard.is_none())
                .unwrap_or(false),
            "sqlite should start closed for short preview hit"
        );

        let short_hits = short_client.search(
            "shortneedle",
            SearchFilters::default(),
            5,
            0,
            FieldMask::FULL,
        )?;

        assert_eq!(short_hits.len(), 1, "expected one short lexical hit");
        assert_eq!(
            short_hits[0].content, short_content,
            "untruncated stored preview is exact full content"
        );
        assert!(
            short_client
                .sqlite
                .lock()
                .map(|guard| guard.is_none())
                .unwrap_or(false),
            "short full-content hit should not lazy-open sqlite"
        );

        Ok(())
    }

    #[test]
    fn filter_fidelity_agent_filter_respected() -> Result<()> {
        // Multiple agents; filter should return only matching agent
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Agent A (codex)
        let conv_a = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("alpha doc".into()),
            workspace: None,
            source_path: dir.path().join("a.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "hello world findme alpha".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        // Agent B (claude)
        let conv_b = NormalizedConversation {
            agent_slug: "claude".into(),
            external_id: None,
            title: Some("beta doc".into()),
            workspace: None,
            source_path: dir.path().join("b.jsonl"),
            started_at: Some(200),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(200),
                content: "hello world findme beta".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv_a)?;
        index.add_conversation(&conv_b)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Search with agent filter for codex only
        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".into());

        let hits = client.search("findme", filters.clone(), 10, 0, FieldMask::FULL)?;

        // Property: all results must have agent == "codex"
        for hit in &hits {
            assert_eq!(
                hit.agent, "codex",
                "Agent filter violated: got agent '{}' instead of 'codex'",
                hit.agent
            );
        }
        assert!(!hits.is_empty(), "Should have found results");

        // Repeat search (should use cache) and verify same property
        let cached_hits = client.search("findme", filters, 10, 0, FieldMask::FULL)?;
        for hit in &cached_hits {
            assert_eq!(hit.agent, "codex", "Cached search violated agent filter");
        }

        Ok(())
    }

    #[test]
    fn filter_fidelity_workspace_filter_respected() -> Result<()> {
        // Multiple workspaces; filter should return only matching workspace
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Workspace A
        let conv_a = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("ws_a doc".into()),
            workspace: Some(std::path::PathBuf::from("/workspace/alpha")),
            source_path: dir.path().join("a.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "workspace test needle".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        // Workspace B
        let conv_b = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("ws_b doc".into()),
            workspace: Some(std::path::PathBuf::from("/workspace/beta")),
            source_path: dir.path().join("b.jsonl"),
            started_at: Some(200),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(200),
                content: "workspace test needle".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv_a)?;
        index.add_conversation(&conv_b)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Search with workspace filter for beta only
        let mut filters = SearchFilters::default();
        filters.workspaces.insert("/workspace/beta".into());

        let hits = client.search("needle", filters.clone(), 10, 0, FieldMask::FULL)?;

        // Property: all results must have workspace == "/workspace/beta"
        for hit in &hits {
            assert_eq!(
                hit.workspace, "/workspace/beta",
                "Workspace filter violated: got '{}' instead of '/workspace/beta'",
                hit.workspace
            );
        }
        assert!(!hits.is_empty(), "Should have found results");

        // Repeat search (should use cache)
        let cached_hits = client.search("needle", filters, 10, 0, FieldMask::FULL)?;
        for hit in &cached_hits {
            assert_eq!(
                hit.workspace, "/workspace/beta",
                "Cached search violated workspace filter"
            );
        }

        Ok(())
    }

    #[test]
    fn filter_fidelity_date_range_respected() -> Result<()> {
        // Multiple dates; filter should return only within range
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Early doc (ts=100)
        let conv_early = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("early".into()),
            workspace: None,
            source_path: dir.path().join("early.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "date range test".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        // Middle doc (ts=500)
        let conv_middle = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("middle".into()),
            workspace: None,
            source_path: dir.path().join("middle.jsonl"),
            started_at: Some(500),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(500),
                content: "date range test".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        // Late doc (ts=900)
        let conv_late = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("late".into()),
            workspace: None,
            source_path: dir.path().join("late.jsonl"),
            started_at: Some(900),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(900),
                content: "date range test".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv_early)?;
        index.add_conversation(&conv_middle)?;
        index.add_conversation(&conv_late)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Filter for middle range only (400-600)
        let filters = SearchFilters {
            created_from: Some(400),
            created_to: Some(600),
            ..Default::default()
        };

        let hits = client.search("range", filters.clone(), 10, 0, FieldMask::FULL)?;

        // Property: all results must have created_at within [400, 600]
        for hit in &hits {
            if let Some(ts) = hit.created_at {
                assert!(
                    (400..=600).contains(&ts),
                    "Date range filter violated: got ts={ts} outside [400, 600]"
                );
            }
        }
        // Should find only the middle doc
        assert_eq!(hits.len(), 1, "Should find exactly 1 doc in range");

        // Repeat search (cache)
        let cached_hits = client.search("range", filters, 10, 0, FieldMask::FULL)?;
        for hit in &cached_hits {
            if let Some(ts) = hit.created_at {
                assert!(
                    (400..=600).contains(&ts),
                    "Cached search violated date range filter"
                );
            }
        }

        Ok(())
    }

    #[test]
    fn filter_fidelity_combined_filters_respected() -> Result<()> {
        // Combine agent + workspace + date filters
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create 4 docs with different combinations
        let combinations = [
            ("codex", "/ws/prod", 100),  // wrong date
            ("claude", "/ws/prod", 500), // correct agent, correct ws, correct date
            ("claude", "/ws/dev", 500),  // correct agent, wrong ws, correct date
            ("claude", "/ws/prod", 900), // correct agent, correct ws, wrong date
        ];

        for (i, (agent, ws, ts)) in combinations.iter().enumerate() {
            let conv = NormalizedConversation {
                agent_slug: (*agent).into(),
                external_id: None,
                title: Some(format!("combo-{i}")),
                workspace: Some(std::path::PathBuf::from(*ws)),
                source_path: dir.path().join(format!("{i}.jsonl")),
                started_at: Some(*ts),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(*ts),
                    content: "hello world combotest query".into(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Filter: claude + /ws/prod + date 400-600
        let mut filters = SearchFilters::default();
        filters.agents.insert("claude".into());
        filters.workspaces.insert("/ws/prod".into());
        filters.created_from = Some(400);
        filters.created_to = Some(600);

        let hits = client.search("combotest", filters.clone(), 10, 0, FieldMask::FULL)?;

        // Should find exactly 1 doc (index 1 in combinations)
        assert_eq!(hits.len(), 1, "Combined filter should match exactly 1 doc");

        for hit in &hits {
            assert_eq!(hit.agent, "claude", "Agent filter violated");
            assert_eq!(hit.workspace, "/ws/prod", "Workspace filter violated");
            if let Some(ts) = hit.created_at {
                assert!((400..=600).contains(&ts), "Date filter violated: ts={ts}");
            }
        }

        // Cache hit
        let cached = client.search("combotest", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(cached.len(), 1, "Cached result count mismatch");

        Ok(())
    }

    #[test]
    fn lexical_hits_normalize_trimmed_local_source_metadata() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("trimmed local doc".into()),
            workspace: None,
            source_path: dir.path().join("trimmed-local.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({
                "cass": {
                    "origin": {
                        "source_id": "  LOCAL  ",
                        "kind": "local"
                    }
                }
            }),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "trimmed local lexical".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let hits = client.search("trimmed", SearchFilters::default(), 10, 0, FieldMask::FULL)?;

        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].source_id, "local");
        assert_eq!(hits[0].origin_kind, "local");

        Ok(())
    }

    #[test]
    fn lexical_hits_normalize_remote_origin_kind_without_source_id() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("remote lexical doc".into()),
            workspace: None,
            source_path: dir.path().join("remote-lexical.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({
                "cass": {
                    "origin": {
                        "source_id": "   ",
                        "kind": "ssh",
                        "host": "dev@laptop"
                    }
                }
            }),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "remote lexical".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let hits = client.search("remote", SearchFilters::default(), 10, 0, FieldMask::FULL)?;

        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].source_id, "dev@laptop");
        assert_eq!(hits[0].origin_kind, "remote");
        assert_eq!(hits[0].origin_host.as_deref(), Some("dev@laptop"));

        Ok(())
    }

    #[test]
    fn lexical_hits_infer_remote_origin_from_host_without_kind() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("legacy host-only lexical doc".into()),
            workspace: None,
            source_path: dir.path().join("legacy-host-only-lexical.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({
                "cass": {
                    "origin": {
                        "source_id": "   ",
                        "host": "dev@laptop"
                    }
                }
            }),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "legacy remote lexical".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let hits = client.search("legacy", SearchFilters::default(), 10, 0, FieldMask::FULL)?;

        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].source_id, "dev@laptop");
        assert_eq!(hits[0].origin_kind, "remote");
        assert_eq!(hits[0].origin_host.as_deref(), Some("dev@laptop"));

        Ok(())
    }

    #[test]
    fn filter_fidelity_source_filter_respected() -> Result<()> {
        // P3.1: Source filter should filter by origin_kind or source_id
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Local source doc
        let conv_local = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("local doc".into()),
            workspace: None,
            source_path: dir.path().join("local.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "source filter test local".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        // Remote source doc (would need to be indexed with ssh origin_kind)
        // For now, test that local filter returns local docs
        index.add_conversation(&conv_local)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Filter for local sources
        let filters = SearchFilters {
            source_filter: SourceFilter::Local,
            ..Default::default()
        };

        let hits = client.search("source", filters.clone(), 10, 0, FieldMask::FULL)?;

        // Property: all results should have source_id == "local"
        for hit in &hits {
            assert_eq!(
                hit.source_id, "local",
                "Source filter violated: got source_id '{}' instead of 'local'",
                hit.source_id
            );
        }
        assert!(!hits.is_empty(), "Should have found local results");

        // Filter for specific source ID
        let filters_id = SearchFilters {
            source_filter: SourceFilter::SourceId("  LOCAL  ".to_string()),
            ..Default::default()
        };

        let hits_id = client.search("source", filters_id, 10, 0, FieldMask::FULL)?;
        for hit in &hits_id {
            assert_eq!(
                hit.source_id, "local",
                "SourceId filter violated: got '{}' instead of 'local'",
                hit.source_id
            );
        }
        assert!(
            !hits_id.is_empty(),
            "Should have found results for source_id=local"
        );

        Ok(())
    }

    #[test]
    fn filter_fidelity_cache_key_isolation() {
        // Different filters should have different cache keys
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let filters_empty = SearchFilters::default();
        let mut filters_agent = SearchFilters::default();
        filters_agent.agents.insert("codex".into());

        let mut filters_ws = SearchFilters::default();
        filters_ws.workspaces.insert("/ws".into());

        let key_empty = client.cache_key("test", &filters_empty);
        let key_agent = client.cache_key("test", &filters_agent);
        let key_ws = client.cache_key("test", &filters_ws);

        // All keys should be different
        assert_ne!(
            key_empty, key_agent,
            "Empty vs agent filter keys should differ"
        );
        assert_ne!(
            key_empty, key_ws,
            "Empty vs workspace filter keys should differ"
        );
        assert_ne!(
            key_agent, key_ws,
            "Agent vs workspace filter keys should differ"
        );

        // Same filter should produce same key
        let mut filters_agent2 = SearchFilters::default();
        filters_agent2.agents.insert("codex".into());
        let key_agent2 = client.cache_key("test", &filters_agent2);
        assert_eq!(key_agent, key_agent2, "Same filter should produce same key");
    }

    // ==========================================================================
    // FTS5 Query Generation Tests (tst.srch.fts)
    // Additional tests for SQL/FTS5 query generation edge cases
    // ==========================================================================

    // --- Additional sanitize_query tests (edge cases) ---

    #[test]
    fn sanitize_query_preserves_unicode_alphanumeric() {
        // Unicode letters and digits should be preserved
        assert_eq!(fs_cass_sanitize_query("こんにちは"), "こんにちは");
        assert_eq!(fs_cass_sanitize_query("café"), "café");
        assert_eq!(fs_cass_sanitize_query("日本語123"), "日本語123");
    }

    #[test]
    fn sanitize_query_handles_multiple_consecutive_special_chars() {
        assert_eq!(fs_cass_sanitize_query("foo---bar"), "foo---bar");
        // a!@#$%^&()b has 9 special chars between a and b: ! @ # $ % ^ & ( )
        assert_eq!(fs_cass_sanitize_query("a!@#$%^&()b"), "a         b");
    }

    // --- Additional WildcardPattern::parse tests (edge cases) ---

    #[test]
    fn wildcard_pattern_empty_after_trim_returns_exact_empty() {
        assert_eq!(
            FsCassWildcardPattern::parse("*"),
            FsCassWildcardPattern::Exact(String::new())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("**"),
            FsCassWildcardPattern::Exact(String::new())
        );
        assert_eq!(
            FsCassWildcardPattern::parse("***"),
            FsCassWildcardPattern::Exact(String::new())
        );
    }

    #[test]
    fn wildcard_pattern_to_regex_generation() {
        // Exact and prefix patterns don't need regex
        assert_eq!(FsCassWildcardPattern::Exact("foo".into()).to_regex(), None);
        assert_eq!(FsCassWildcardPattern::Prefix("foo".into()).to_regex(), None);
        // Suffix and substring need regex
        // Suffix needs $ anchor for "ends with" semantics
        assert_eq!(
            FsCassWildcardPattern::Suffix("foo".into()).to_regex(),
            Some(".*foo$".into())
        );
        assert_eq!(
            FsCassWildcardPattern::Substring("foo".into()).to_regex(),
            Some(".*foo.*".into())
        );
    }

    // --- Additional parse_boolean_query tests (edge cases) ---

    #[test]
    fn parse_boolean_query_prefix_minus_not() {
        // Prefix minus at start of query should trigger NOT
        let tokens = fs_cass_parse_boolean_query("-world");
        let expected = vec![
            FsCassQueryToken::Not,
            FsCassQueryToken::Term("world".into()),
        ];
        assert_eq!(tokens, expected);

        // Prefix minus after space should trigger NOT
        let tokens = fs_cass_parse_boolean_query("hello -world");
        let expected = vec![
            FsCassQueryToken::Term("hello".into()),
            FsCassQueryToken::Not,
            FsCassQueryToken::Term("world".into()),
        ];
        assert_eq!(tokens, expected);
    }

    #[test]
    fn parse_boolean_query_empty_quoted_phrase_ignored() {
        let tokens = parse_boolean_query("\"\"");
        assert!(tokens.is_empty());

        let tokens = parse_boolean_query("foo \"\" bar");
        let expected: QueryTokenList = vec![
            QueryToken::Term("foo".into()),
            QueryToken::Term("bar".into()),
        ];
        assert_eq!(tokens, expected);
    }

    #[test]
    fn parse_boolean_query_unclosed_quote() {
        // Unclosed quote should collect until end
        let tokens = parse_boolean_query("\"hello world");
        let expected: QueryTokenList = vec![QueryToken::Phrase("hello world".into())];
        assert_eq!(tokens, expected);
    }

    #[test]
    fn transpile_to_fts5_rejects_leading_unary_not_queries() {
        assert_eq!(transpile_to_fts5("NOT foo"), None);
        assert_eq!(transpile_to_fts5("-foo"), None);
    }

    #[test]
    fn transpile_to_fts5_rejects_or_not_forms_it_cannot_represent() {
        assert_eq!(transpile_to_fts5("foo OR NOT bar"), None);
        assert_eq!(transpile_to_fts5("foo NOT bar OR baz"), None);
    }

    #[test]
    fn transpile_to_fts5_ignores_leading_or() {
        assert_eq!(transpile_to_fts5("OR test"), Some("test".to_string()));
        assert_eq!(
            transpile_to_fts5("OR foo-bar"),
            Some("(foo AND bar)".to_string())
        );
    }

    #[test]
    fn transpile_to_fts5_splits_hyphenated_subterms_for_sqlite_fts() {
        assert_eq!(
            transpile_to_fts5("br-123.jsonl"),
            Some("(br AND 123 AND jsonl)".to_string())
        );
        assert_eq!(
            transpile_to_fts5("br-123.json*"),
            Some("(br AND 123 AND json*)".to_string())
        );
    }

    #[test]
    fn transpile_to_fts5_preserves_supported_binary_not() {
        assert_eq!(
            transpile_to_fts5("foo NOT bar").as_deref(),
            Some("foo NOT bar")
        );
        assert_eq!(
            transpile_to_fts5("foo NOT bar-baz"),
            Some("foo NOT (bar AND baz)".to_string())
        );
    }

    #[test]
    fn search_sqlite_fts5_returns_empty_when_sqlite_is_unavailable() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: false,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: "fts5-disabled".to_string(),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let hits = client.search_sqlite_fts5(
            Path::new("/nonexistent"),
            "test query",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        );

        assert!(hits.is_ok(), "disabled FTS5 path should stay non-fatal");
        assert!(
            hits.unwrap().is_empty(),
            "unavailable SQLite fallback should keep returning an empty result set"
        );
    }

    /// `coding_agent_session_search-k0e5p` (ibuuh.24.2 sub-bead):
    /// E2E equivalence gate for the rank+hydrate FTS5 fallback split
    /// landed in peer commit c91ea038. The peer's existing unit test
    /// pins the rank-SQL SHAPE (no content columns referenced) but
    /// nothing pins the user-facing RESULT-SET equivalence. A
    /// regression where the hydrate phase silently re-orders, drops,
    /// or re-filters hits would slip past the SQL-shape check and
    /// produce user-visible quality changes.
    ///
    /// This test pins the prefix invariant (same pattern as bead
    /// 1dd5u for the lexical search path): seed N ranked hits in the
    /// FTS5 fallback DB, run search_sqlite_fts5 at limit=K and
    /// limit=N, assert the smaller-limit result is a prefix of the
    /// larger-limit result. A regression in either rank or hydrate
    /// (re-order, drop, re-filter) trips immediately.
    ///
    /// Pins three invariants:
    /// 1. Smaller-limit hits are a strict prefix of larger-limit hits.
    /// 2. Limit=N returns exactly N matches when ≥N candidates exist.
    /// 3. Limit=0 returns empty (boundary case the rank+hydrate
    ///    split could break by hydrating before honoring the limit).
    #[test]
    fn search_sqlite_fts5_rank_and_hydrate_split_preserves_limit_prefix_invariant() -> Result<()> {
        let conn = Connection::open(":memory:")?;
        conn.execute_batch(
            "CREATE TABLE sources (id TEXT PRIMARY KEY, kind TEXT);
             CREATE TABLE agents (id INTEGER PRIMARY KEY, slug TEXT NOT NULL UNIQUE);
             CREATE TABLE workspaces (id INTEGER PRIMARY KEY, path TEXT NOT NULL UNIQUE);
             CREATE TABLE conversations (
                id INTEGER PRIMARY KEY,
                agent_id INTEGER,
                workspace_id INTEGER,
                source_id TEXT,
                origin_host TEXT,
                title TEXT,
                source_path TEXT
             );
             CREATE TABLE messages (
                id INTEGER PRIMARY KEY,
                conversation_id INTEGER,
                idx INTEGER,
                content TEXT,
                created_at INTEGER
             );
             CREATE VIRTUAL TABLE fts_messages USING fts5(
                content,
                title,
                agent,
                workspace,
                source_path,
                created_at UNINDEXED,
                message_id UNINDEXED,
                tokenize='porter'
             );",
        )?;
        conn.execute("INSERT INTO sources(id, kind) VALUES('local', 'local')")?;
        conn.execute("INSERT INTO agents(id, slug) VALUES(1, 'codex')")?;
        conn.execute("INSERT INTO workspaces(id, path) VALUES(1, '/tmp/k0e5p')")?;

        // Seed N=6 messages all matching the same query token. Each
        // gets a distinct message_id + content shape so the prefix
        // assertion can pin specific ordering rather than just
        // counts. The bm25 score depends on per-row term frequency;
        // we vary `rankprobe` repetition (1×..6×) so the rank phase
        // produces a deterministic descending order.
        for (i, repeats) in (1..=6_i64).enumerate() {
            let conv_id = i as i64 + 1;
            let msg_id = (i as i64 + 1) * 10;
            conn.execute_compat(
                "INSERT INTO conversations(id, agent_id, workspace_id, source_id, \
                 origin_host, title, source_path) \
                 VALUES(?1, 1, 1, 'local', NULL, ?2, ?3)",
                params![
                    conv_id,
                    format!("k0e5p-{}", i),
                    format!("/tmp/k0e5p/{}.jsonl", i),
                ],
            )?;
            let content = "rankprobe ".repeat(repeats as usize);
            conn.execute_compat(
                "INSERT INTO messages(id, conversation_id, idx, content, created_at) \
                 VALUES(?1, ?2, ?3, ?4, ?5)",
                params![
                    msg_id,
                    conv_id,
                    i as i64,
                    content.as_str(),
                    1_700_000_000_i64 + i as i64
                ],
            )?;
            conn.execute_compat(
                "INSERT INTO fts_messages(rowid, content, title, agent, workspace, \
                 source_path, created_at, message_id) \
                 VALUES(?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)",
                params![
                    msg_id,
                    content.as_str(),
                    format!("k0e5p-{}", i),
                    "codex",
                    "/tmp/k0e5p",
                    format!("/tmp/k0e5p/{}.jsonl", i),
                    1_700_000_000_i64 + i as i64,
                    msg_id,
                ],
            )?;
        }

        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(Some(SendConnection(conn))),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: false,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:k0e5p"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        // Hit-key tuple: (source_path, line_number) is the stable
        // operator-visible identity. Two limits that share a prefix
        // must produce hits with the same identities in the same
        // order across that prefix.
        fn hit_keys(hits: &[SearchHit]) -> Vec<(String, Option<usize>)> {
            hits.iter()
                .map(|h| (h.source_path.clone(), h.line_number))
                .collect()
        }

        let large_hits = client.search_sqlite_fts5(
            Path::new(":memory:"),
            "rankprobe",
            SearchFilters::default(),
            6,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(
            large_hits.len(),
            6,
            "limit=N must return all N candidates when the corpus has exactly N matches"
        );

        let small_hits = client.search_sqlite_fts5(
            Path::new(":memory:"),
            "rankprobe",
            SearchFilters::default(),
            3,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(small_hits.len(), 3, "limit=3 must return exactly 3 hits");

        // Invariant 1: smaller-limit hits are a STRICT prefix of the
        // larger-limit hits — same identity, same order.
        let large_keys = hit_keys(&large_hits);
        let small_keys = hit_keys(&small_hits);
        assert_eq!(
            small_keys,
            large_keys[..3],
            "limit=3 hit keys MUST be the first 3 of limit=6 hit keys (rank+hydrate \
             split must not re-order or re-filter); small={small_keys:?} \
             large_prefix={:?}",
            &large_keys[..3]
        );

        // Invariant 2: hit content is also identical across the
        // shared prefix — the hydrate phase preserves the content
        // string the rank phase ranked. A regression where hydrate
        // pulled from a different DB row than rank pointed at would
        // trip this even if the keys aligned.
        for (idx, (small, large)) in small_hits.iter().zip(large_hits.iter()).enumerate() {
            assert_eq!(
                small.content, large.content,
                "hit[{idx}] content must agree across limit=3 and limit=6: \
                 small={:?} large={:?}",
                small.content, large.content
            );
            assert_eq!(
                small.title, large.title,
                "hit[{idx}] title must agree across limit=3 and limit=6"
            );
        }

        // Invariant 3: limit=0 boundary. The rank+hydrate split could
        // break this by hydrating before honoring the limit; pinning
        // it directly catches that regression class.
        let zero_hits = client.search_sqlite_fts5(
            Path::new(":memory:"),
            "rankprobe",
            SearchFilters::default(),
            0,
            0,
            FieldMask::FULL,
        )?;
        assert!(
            zero_hits.is_empty(),
            "limit=0 must return zero hits even though the rank phase has candidates; \
             got {} hits",
            zero_hits.len()
        );

        Ok(())
    }

    // --- levenshtein_distance tests ---

    #[test]
    fn levenshtein_distance_identical_strings() {
        assert_eq!(levenshtein_distance("hello", "hello"), 0);
        assert_eq!(levenshtein_distance("", ""), 0);
    }

    #[test]
    fn levenshtein_distance_insertions() {
        assert_eq!(levenshtein_distance("", "abc"), 3);
        assert_eq!(levenshtein_distance("cat", "cats"), 1);
    }

    #[test]
    fn levenshtein_distance_deletions() {
        assert_eq!(levenshtein_distance("abc", ""), 3);
        assert_eq!(levenshtein_distance("cats", "cat"), 1);
    }

    #[test]
    fn levenshtein_distance_substitutions() {
        assert_eq!(levenshtein_distance("cat", "bat"), 1);
        assert_eq!(levenshtein_distance("kitten", "sitten"), 1);
    }

    #[test]
    fn levenshtein_distance_mixed_operations() {
        assert_eq!(levenshtein_distance("kitten", "sitting"), 3);
        assert_eq!(levenshtein_distance("saturday", "sunday"), 3);
    }

    // --- is_tool_invocation_noise tests ---

    #[test]
    fn is_tool_invocation_noise_allows_real_content() {
        assert!(!is_tool_invocation_noise("This is a normal message"));
        assert!(!is_tool_invocation_noise(
            "Let me use the Tool feature to accomplish this task. Here is the implementation..."
        ));
        // Long content that happens to start with [Tool: should be allowed if it's substantial
        let long_content = "[Tool: Read] Now here is a lot of useful content that explains the implementation details and provides context for the changes being made to the codebase.";
        assert!(!is_tool_invocation_noise(long_content));
    }

    #[test]
    fn is_tool_invocation_noise_handles_short_tool_markers() {
        assert!(is_tool_invocation_noise("[tool: x]"));
        assert!(is_tool_invocation_noise("tool: bash"));
    }

    // --- Integration tests for boolean queries through search ---

    #[test]
    fn search_boolean_and_filters_results() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create documents with different word combinations
        let conv1 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc1".into()),
            workspace: None,
            source_path: dir.path().join("1.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "alpha beta gamma".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        let conv2 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc2".into()),
            workspace: None,
            source_path: dir.path().join("2.jsonl"),
            started_at: Some(2),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(2),
                content: "alpha delta".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv1)?;
        index.add_conversation(&conv2)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "alpha AND beta" should only match doc1
        let hits = client.search(
            "alpha AND beta",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        assert!(hits[0].content.contains("gamma"));

        // "alpha AND delta" should only match doc2
        let hits = client.search(
            "alpha AND delta",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        assert!(hits[0].content.contains("delta"));

        Ok(())
    }

    #[test]
    fn search_boolean_or_expands_results() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv1 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc1".into()),
            workspace: None,
            source_path: dir.path().join("1.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "unique xyzzy term".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        let conv2 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc2".into()),
            workspace: None,
            source_path: dir.path().join("2.jsonl"),
            started_at: Some(2),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(2),
                content: "unique plugh term".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv1)?;
        index.add_conversation(&conv2)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "xyzzy OR plugh" should match both docs
        let hits = client.search(
            "xyzzy OR plugh",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 2);

        Ok(())
    }

    #[test]
    fn search_boolean_not_excludes_results() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv1 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc1".into()),
            workspace: None,
            source_path: dir.path().join("1.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "nottest keep this".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        let conv2 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc2".into()),
            workspace: None,
            source_path: dir.path().join("2.jsonl"),
            started_at: Some(2),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(2),
                content: "nottest exclude this".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv1)?;
        index.add_conversation(&conv2)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "nottest NOT exclude" should only match doc1 (has nottest but NOT exclude)
        let hits = client.search(
            "nottest NOT exclude",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        // Verify we got the right doc by checking it doesn't contain "exclude"
        assert!(
            !hits[0].content.contains("exclude"),
            "NOT exclude should filter out doc with 'exclude'"
        );

        // Prefix "-" exclusion should behave like NOT for simple queries.
        let hits = client.search(
            "nottest -exclude",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        assert!(
            !hits[0].content.contains("exclude"),
            "Prefix -exclude should filter out doc with 'exclude'"
        );

        Ok(())
    }

    #[test]
    fn search_phrase_query_matches_exact_sequence() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv1 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc1".into()),
            workspace: None,
            source_path: dir.path().join("1.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "the quick brown fox".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        let conv2 = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc2".into()),
            workspace: None,
            source_path: dir.path().join("2.jsonl"),
            started_at: Some(2),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(2),
                content: "the brown quick fox".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv1)?;
        index.add_conversation(&conv2)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // "quick brown" (without quotes) should match both (words just need to be present)
        let hits = client.search(
            "quick brown",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 2);

        // "\"quick brown\"" should match exact order only
        let hits = client.search(
            "\"quick brown\"",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 1);
        assert!(hits[0].content.contains("quick brown"));

        Ok(())
    }

    #[test]
    fn search_dot_punctuation_splits_terms_but_hyphens_preserve_compound_semantics() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("doc".into()),
            workspace: None,
            source_path: dir.path().join("3.jsonl"),
            started_at: Some(1),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(1),
                content: "foo bar baz".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        let hits = client.search("foo.bar", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);

        let hits = client.search("foo-bar", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 0);

        Ok(())
    }

    // ========================================================================
    // QueryExplanation tests
    // ========================================================================

    #[test]
    fn explanation_classifies_simple_query() {
        let exp = QueryExplanation::analyze("hello", &SearchFilters::default());
        assert_eq!(exp.query_type, QueryType::Simple);
        assert_eq!(exp.index_strategy, IndexStrategy::EdgeNgram);
        assert_eq!(exp.estimated_cost, QueryCost::Low);
        assert!(exp.parsed.terms.len() == 1);
        assert_eq!(exp.parsed.terms[0].text, "hello");
        assert!(!exp.parsed.terms[0].subterms.is_empty());
        assert_eq!(exp.parsed.terms[0].subterms[0].pattern, "exact");
    }

    #[test]
    fn explanation_classifies_wildcard_query() {
        let exp = QueryExplanation::analyze("*handler*", &SearchFilters::default());
        assert_eq!(exp.query_type, QueryType::Wildcard);
        assert_eq!(exp.index_strategy, IndexStrategy::RegexScan);
        assert_eq!(exp.estimated_cost, QueryCost::High);
        assert!(!exp.parsed.terms[0].subterms.is_empty());
        assert!(
            exp.parsed.terms[0].subterms[0]
                .pattern
                .contains("substring")
        );
        assert!(exp.warnings.iter().any(|w| w.contains("regex scan")));
    }

    #[test]
    fn explanation_classifies_boolean_query() {
        let exp = QueryExplanation::analyze("foo AND bar", &SearchFilters::default());
        assert_eq!(exp.query_type, QueryType::Boolean);
        assert_eq!(exp.index_strategy, IndexStrategy::BooleanCombination);
        assert!(exp.parsed.operators.contains(&"AND".to_string()));
    }

    #[test]
    fn explanation_classifies_phrase_query() {
        let exp = QueryExplanation::analyze("\"exact phrase\"", &SearchFilters::default());
        assert_eq!(exp.query_type, QueryType::Phrase);
        assert!(exp.parsed.phrases.contains(&"exact phrase".to_string()));
    }

    #[test]
    fn explanation_handles_filtered_query() {
        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".to_string());

        let exp = QueryExplanation::analyze("test", &filters);
        assert_eq!(exp.query_type, QueryType::Filtered);
        assert_eq!(exp.filters_summary.agent_count, 1);
        assert!(
            exp.filters_summary
                .description
                .as_ref()
                .unwrap()
                .contains("1 agent")
        );
        assert!(exp.warnings.iter().any(|w| w.contains("codex")));
    }

    #[test]
    fn explanation_handles_empty_query() {
        let exp = QueryExplanation::analyze("", &SearchFilters::default());
        assert_eq!(exp.query_type, QueryType::Empty);
        assert_eq!(exp.index_strategy, IndexStrategy::FullScan);
        assert_eq!(exp.estimated_cost, QueryCost::High);
        assert!(exp.warnings.iter().any(|w| w.contains("Empty query")));
    }

    #[test]
    fn explanation_warns_short_terms() {
        let exp = QueryExplanation::analyze("a", &SearchFilters::default());
        assert!(exp.warnings.iter().any(|w| w.contains("Very short term")));
    }

    #[test]
    fn explanation_with_wildcard_fallback() {
        let exp = QueryExplanation::analyze("test", &SearchFilters::default())
            .with_wildcard_fallback(true);
        assert!(exp.wildcard_applied);
        // Message starts with capital W: "Wildcard fallback was applied..."
        assert!(exp.warnings.iter().any(|w| w.contains("Wildcard fallback")));
    }

    #[test]
    fn explanation_complex_query_has_higher_cost() {
        let exp = QueryExplanation::analyze(
            "foo AND bar OR baz NOT qux AND \"phrase here\"",
            &SearchFilters::default(),
        );
        assert_eq!(exp.query_type, QueryType::Boolean);
        // Complex query should have Medium or High cost
        assert!(matches!(
            exp.estimated_cost,
            QueryCost::Medium | QueryCost::High
        ));
    }

    #[test]
    fn explanation_preserves_original_query() {
        let exp = QueryExplanation::analyze("Hello World!", &SearchFilters::default());
        assert_eq!(exp.original_query, "Hello World!");
        // Sanitized replaces special chars with spaces but preserves case
        assert!(exp.sanitized_query.contains("Hello"));
        // ! is replaced with space
        assert!(!exp.sanitized_query.contains("!"));
    }

    #[test]
    fn explanation_detects_not_operator() {
        let exp = QueryExplanation::analyze("foo NOT bar", &SearchFilters::default());
        assert!(exp.parsed.operators.contains(&"NOT".to_string()));
        // Second term should be marked as negated
        assert!(
            exp.parsed
                .terms
                .iter()
                .any(|t| t.negated && t.text == "bar")
        );
    }

    #[test]
    fn explanation_implicit_and() {
        let exp = QueryExplanation::analyze("foo bar", &SearchFilters::default());
        assert!(exp.parsed.implicit_and);
        assert_eq!(exp.parsed.terms.len(), 2);
    }

    #[test]
    fn explanation_serializes_to_json() {
        let exp = QueryExplanation::analyze("test query", &SearchFilters::default());
        let json = serde_json::to_value(&exp).expect("should serialize");
        assert!(json["original_query"].is_string());
        assert!(json["query_type"].is_string());
        assert!(json["index_strategy"].is_string());
        assert!(json["estimated_cost"].is_string());
        assert!(json["parsed"]["terms"].is_array());
    }

    // =========================================================================
    // Multi-filter combination tests (bead yln.2)
    // =========================================================================

    #[test]
    fn search_multi_filter_agent_workspace_time() -> Result<()> {
        // Test combining agent, workspace, and time range filters
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create 4 conversations with different combinations
        let convs = [
            ("codex", "/ws/alpha", 100, "needle alpha codex"),
            ("claude", "/ws/alpha", 200, "needle alpha claude"),
            ("codex", "/ws/beta", 150, "needle beta codex"),
            ("codex", "/ws/alpha", 300, "needle alpha codex late"),
        ];

        for (i, (agent, ws, ts, content)) in convs.iter().enumerate() {
            let conv = NormalizedConversation {
                agent_slug: (*agent).into(),
                external_id: None,
                title: Some(format!("conv-{i}")),
                workspace: Some(std::path::PathBuf::from(*ws)),
                source_path: dir.path().join(format!("{i}.jsonl")),
                started_at: Some(*ts),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(*ts),
                    content: (*content).into(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Filter: codex + alpha + time 50-250
        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".into());
        filters.workspaces.insert("/ws/alpha".into());
        filters.created_from = Some(50);
        filters.created_to = Some(250);

        let hits = client.search("needle", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(
            hits.len(),
            1,
            "Should match only one conv (codex + alpha + ts=100)"
        );
        assert_eq!(hits[0].agent, "codex");
        assert_eq!(hits[0].workspace, "/ws/alpha");
        assert!(hits[0].content.contains("alpha codex"));
        assert!(!hits[0].content.contains("late")); // Not the ts=300 one

        Ok(())
    }

    #[test]
    fn search_multi_agent_filter() -> Result<()> {
        // Test filtering by multiple agents
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        for agent in ["codex", "claude", "cline", "gemini"] {
            let conv = NormalizedConversation {
                agent_slug: agent.into(),
                external_id: None,
                title: Some(format!("{agent}-conv")),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: dir.path().join(format!("{agent}.jsonl")),
                started_at: Some(100),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100),
                    content: format!("needle from {agent}"),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Filter for codex and claude only
        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".into());
        filters.agents.insert("claude".into());

        let hits = client.search("needle", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 2);
        let agents: Vec<_> = hits.iter().map(|h| h.agent.as_str()).collect();
        assert!(agents.contains(&"codex"));
        assert!(agents.contains(&"claude"));
        assert!(!agents.contains(&"cline"));
        assert!(!agents.contains(&"gemini"));

        Ok(())
    }

    // =========================================================================
    // Cache metrics tests (bead yln.2)
    // =========================================================================

    #[test]
    fn cache_metrics_incremented_on_operations() {
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        // Initial metrics should be zero
        let (hits, miss, shortfall, reloads, _) = client.metrics.snapshot_all();
        assert_eq!((hits, miss, shortfall, reloads), (0, 0, 0, 0));

        // Simulate operations
        client.metrics.inc_cache_hits();
        client.metrics.inc_cache_hits();
        client.metrics.inc_cache_miss();
        client.metrics.inc_cache_shortfall();
        client.metrics.inc_reload();

        let (hits, miss, shortfall, reloads, _) = client.metrics.snapshot_all();
        assert_eq!(hits, 2);
        assert_eq!(miss, 1);
        assert_eq!(shortfall, 1);
        assert_eq!(reloads, 1);
    }

    #[test]
    fn cache_shard_name_deterministic() {
        // Verify that shard name generation is deterministic for same filters
        let client = SearchClient {
            reader: None,
            sqlite: Mutex::new(None),
            sqlite_path: None,
            prefix_cache: Mutex::new(CacheShards::new(*CACHE_TOTAL_CAP, *CACHE_BYTE_CAP)),
            reload_on_search: true,
            last_reload: Mutex::new(None),
            last_generation: Mutex::new(None),
            reload_epoch: Arc::new(AtomicU64::new(0)),
            warm_tx: None,
            _warm_handle: None,
            metrics: Metrics::default(),
            cache_namespace: format!("v{CACHE_KEY_VERSION}|schema:test"),
            semantic: Mutex::new(None),
            last_tantivy_total_count: Mutex::new(None),
        };

        let filters1 = SearchFilters::default();
        let mut filters2 = SearchFilters::default();
        filters2.agents.insert("codex".into());
        let mut filters3 = SearchFilters::default();
        filters3.workspaces.insert("/tmp/cass-workspace".into());

        // Same filters should always produce same shard name
        let shard1_first = client.shard_name(&filters1);
        let shard1_second = client.shard_name(&filters1);
        assert_eq!(
            shard1_first, shard1_second,
            "Same filters should produce same shard name"
        );

        // Different filters produce different shard names
        let shard2 = client.shard_name(&filters2);
        assert_ne!(
            shard1_first, shard2,
            "Different filters should produce different shard names"
        );

        // Shard name is deterministic
        assert_eq!(shard2, client.shard_name(&filters2));
        assert_eq!(
            client.shard_name(&filters3),
            "workspace:/tmp/cass-workspace"
        );
    }

    // =========================================================================
    // Wildcard fallback edge cases (bead yln.2)
    // =========================================================================

    #[test]
    fn wildcard_fallback_respects_filter_constraints() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create conversations that would match wildcard but not filter
        let conv_match = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("match".into()),
            workspace: Some(std::path::PathBuf::from("/target")),
            source_path: dir.path().join("match.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "unique specific term here".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };

        let conv_other = NormalizedConversation {
            agent_slug: "claude".into(),
            external_id: None,
            title: Some("other".into()),
            workspace: Some(std::path::PathBuf::from("/other")),
            source_path: dir.path().join("other.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "unique specific also here".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };

        index.add_conversation(&conv_match)?;
        index.add_conversation(&conv_other)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Search with filter that only matches conv_match
        let mut filters = SearchFilters::default();
        filters.agents.insert("codex".into());

        let result =
            client.search_with_fallback("unique", filters.clone(), 10, 0, 100, FieldMask::FULL)?;
        // Should only return the codex conversation, not claude
        assert!(result.hits.iter().all(|h| h.agent == "codex"));

        Ok(())
    }

    #[test]
    fn wildcard_fallback_short_query_triggers_prefix() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "codex".into(),
            external_id: None,
            title: Some("test".into()),
            workspace: None,
            source_path: dir.path().join("test.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "authentication authorization oauth".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Short prefix "auth" should match "authentication" and "authorization"
        let result = client.search_with_fallback(
            "auth",
            SearchFilters::default(),
            10,
            0,
            100,
            FieldMask::FULL,
        )?;
        assert!(
            !result.hits.is_empty(),
            "Short prefix should match via prefix search"
        );
        assert!(result.hits[0].content.contains("auth"));

        Ok(())
    }

    // =========================================================================
    // Real fixture tests with metrics (bead yln.2)
    // =========================================================================

    #[test]
    fn search_real_fixture_multiple_messages() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create a realistic conversation with multiple messages
        let conv = NormalizedConversation {
            agent_slug: "claude_code".into(),
            external_id: Some("conv-123".into()),
            title: Some("Implementing authentication".into()),
            workspace: Some(std::path::PathBuf::from("/home/user/project")),
            source_path: dir.path().join("session-1.jsonl"),
            started_at: Some(1700000000000),
            ended_at: Some(1700000060000),
            metadata: serde_json::json!({
                "model": "claude-3-sonnet",
                "tokens": 1500
            }),
            messages: vec![
                NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: Some("developer".into()),
                    created_at: Some(1700000000000),
                    content: "Help me implement JWT authentication for my Express API".into(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                },
                NormalizedMessage {
                    idx: 1,
                    role: "assistant".into(),
                    author: Some("claude".into()),
                    created_at: Some(1700000010000),
                    content: "I'll help you implement JWT authentication. First, let's install the required packages.".into(),
                    extra: serde_json::json!({}),
                    snippets: vec![NormalizedSnippet {
                        file_path: Some("package.json".into()),
                        start_line: Some(1),
                        end_line: Some(5),
                        language: Some("json".into()),
                        snippet_text: Some(r#"{"dependencies":{"jsonwebtoken":"^9.0.0"}}"#.into()),
                    }],
                    invocations: Vec::new(),
                },
                NormalizedMessage {
                    idx: 2,
                    role: "user".into(),
                    author: Some("developer".into()),
                    created_at: Some(1700000030000),
                    content: "Can you also add refresh token support?".into(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                },
            ],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Search for various terms that should match
        let hits = client.search(
            "JWT authentication",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert!(!hits.is_empty(), "Should find JWT authentication");
        assert!(hits.iter().any(|h| h.agent == "claude_code"));
        assert!(
            hits.iter()
                .any(|h| h.snippet.contains("JWT") || h.snippet.contains("authentication"))
        );

        // Search for assistant response content
        let hits = client.search(
            "required packages",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert!(
            !hits.is_empty(),
            "Should find 'required packages' in assistant response"
        );

        // Search for user question about refresh tokens
        let hits = client.search(
            "refresh token",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert!(!hits.is_empty(), "Should find refresh token");
        assert!(hits.iter().any(|h| h.content.contains("refresh")));

        Ok(())
    }

    #[test]
    fn search_deduplication_with_similar_content() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create two conversations with very similar content
        for i in 0..2 {
            let conv = NormalizedConversation {
                agent_slug: "codex".into(),
                external_id: None,
                title: Some(format!("similar-{i}")),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: dir.path().join(format!("similar-{i}.jsonl")),
                started_at: Some(100 + i),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100 + i),
                    // Exactly the same content
                    content: "implement the sorting algorithm".into(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let result = client.search_with_fallback(
            "sorting algorithm",
            SearchFilters::default(),
            10,
            0,
            100,
            FieldMask::FULL,
        )?;

        // Both should be returned (different source_paths mean different conversations)
        // but if they have exact same content from same source, dedup should apply
        assert!(!result.hits.is_empty());

        Ok(())
    }

    // =========================================================================
    // Session paths filter tests (chained searches)
    // =========================================================================

    #[test]
    fn search_session_paths_filter() -> Result<()> {
        // Test filtering by specific session source paths (for chained searches)
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        // Create 3 conversations with different source paths
        let paths = [
            dir.path().join("session-a.jsonl"),
            dir.path().join("session-b.jsonl"),
            dir.path().join("session-c.jsonl"),
        ];

        for (i, path) in paths.iter().enumerate() {
            let conv = NormalizedConversation {
                agent_slug: "claude".into(),
                external_id: None,
                title: Some(format!("session-{}", i)),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: path.clone(),
                started_at: Some(100 + i as i64),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100 + i as i64),
                    content: format!("needle content for session {}", i),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // First, search without filter - should get all 3
        let hits_all = client.search("needle", SearchFilters::default(), 10, 0, FieldMask::FULL)?;
        assert_eq!(hits_all.len(), 3, "Should find all 3 sessions");

        // Now filter to only sessions A and C
        let mut filters = SearchFilters::default();
        filters
            .session_paths
            .insert(paths[0].to_string_lossy().to_string());
        filters
            .session_paths
            .insert(paths[2].to_string_lossy().to_string());

        let hits_filtered = client.search("needle", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(
            hits_filtered.len(),
            2,
            "Should find only 2 sessions (A and C)"
        );

        // Verify the correct sessions are returned
        let filtered_paths: HashSet<&str> = hits_filtered
            .iter()
            .map(|h| h.source_path.as_str())
            .collect();
        assert!(filtered_paths.contains(paths[0].to_string_lossy().as_ref()));
        assert!(filtered_paths.contains(paths[2].to_string_lossy().as_ref()));
        assert!(!filtered_paths.contains(paths[1].to_string_lossy().as_ref()));

        Ok(())
    }

    #[test]
    fn lexical_session_paths_filter_retries_past_initial_page() -> Result<()> {
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;
        let requested_path = dir.path().join("requested-session.jsonl");

        for i in 0..4 {
            let conv = NormalizedConversation {
                agent_slug: "claude".into(),
                external_id: None,
                title: Some(format!("distractor-{i}")),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: dir.path().join(format!("distractor-{i}.jsonl")),
                started_at: Some(100 + i as i64),
                ended_at: None,
                metadata: serde_json::json!({}),
                messages: vec![NormalizedMessage {
                    idx: 0,
                    role: "user".into(),
                    author: None,
                    created_at: Some(100 + i as i64),
                    content: "needle needle needle high ranking distractor".into(),
                    extra: serde_json::json!({}),
                    snippets: vec![],
                    invocations: Vec::new(),
                }],
            };
            index.add_conversation(&conv)?;
        }

        let requested = NormalizedConversation {
            agent_slug: "claude".into(),
            external_id: None,
            title: Some("requested".into()),
            workspace: Some(std::path::PathBuf::from("/ws")),
            source_path: requested_path.clone(),
            started_at: Some(200),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(200),
                content: "needle requested session should survive post-filter paging".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&requested)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");
        let mut filters = SearchFilters::default();
        filters
            .session_paths
            .insert(requested_path.to_string_lossy().to_string());

        let hits = client.search("needle", filters, 1, 0, FieldMask::FULL)?;

        assert_eq!(hits.len(), 1);
        assert_eq!(hits[0].source_path, requested_path.to_string_lossy());

        Ok(())
    }

    #[test]
    fn search_session_paths_empty_filter_returns_all() -> Result<()> {
        // Empty session_paths filter should not restrict results
        let dir = TempDir::new()?;
        let mut index = TantivyIndex::open_or_create(dir.path())?;

        let conv = NormalizedConversation {
            agent_slug: "claude".into(),
            external_id: None,
            title: Some("test".into()),
            workspace: Some(std::path::PathBuf::from("/ws")),
            source_path: dir.path().join("test.jsonl"),
            started_at: Some(100),
            ended_at: None,
            metadata: serde_json::json!({}),
            messages: vec![NormalizedMessage {
                idx: 0,
                role: "user".into(),
                author: None,
                created_at: Some(100),
                content: "needle content".into(),
                extra: serde_json::json!({}),
                snippets: vec![],
                invocations: Vec::new(),
            }],
        };
        index.add_conversation(&conv)?;
        index.commit()?;

        let client = SearchClient::open(dir.path(), None)?.expect("index present");

        // Empty session_paths should not filter
        let filters = SearchFilters::default();
        assert!(filters.session_paths.is_empty());

        let hits = client.search("needle", filters, 10, 0, FieldMask::FULL)?;
        assert_eq!(hits.len(), 1);

        Ok(())
    }

    #[test]
    fn search_client_reads_federated_lexical_bundle_as_one_corpus() -> Result<()> {
        let root = TempDir::new()?;
        let shard_a = root.path().join("shard-a");
        let shard_b = root.path().join("shard-b");
        let published = root.path().join("published");

        let mut shard_a_index = TantivyIndex::open_or_create(&shard_a)?;
        let mut shard_b_index = TantivyIndex::open_or_create(&shard_b)?;

        let make_conv =
            |external_id: &str, title: &str, source_path: &str, tag: &str| NormalizedConversation {
                agent_slug: "codex".into(),
                external_id: Some(external_id.into()),
                title: Some(title.into()),
                workspace: Some(std::path::PathBuf::from("/ws")),
                source_path: std::path::PathBuf::from(source_path),
                started_at: Some(1_700_000_100_000),
                ended_at: Some(1_700_000_100_100),
                metadata: json!({}),
                messages: vec![
                    NormalizedMessage {
                        idx: 0,
                        role: "user".into(),
                        author: None,
                        created_at: Some(1_700_000_100_010),
                        content: format!("shared federated needle {tag} user"),
                        extra: json!({}),
                        snippets: vec![],
                        invocations: Vec::new(),
                    },
                    NormalizedMessage {
                        idx: 1,
                        role: "assistant".into(),
                        author: None,
                        created_at: Some(1_700_000_100_020),
                        content: format!("shared federated needle {tag} assistant"),
                        extra: json!({}),
                        snippets: vec![],
                        invocations: Vec::new(),
                    },
                ],
            };

        let conv_a = make_conv(
            "fed-query-a",
            "Fed Query A",
            "/tmp/fed-query-a.jsonl",
            "alpha",
        );
        let conv_b = make_conv(
            "fed-query-b",
            "Fed Query B",
            "/tmp/fed-query-b.jsonl",
            "beta",
        );

        shard_a_index.add_conversation(&conv_a)?;
        shard_b_index.add_conversation(&conv_b)?;
        shard_a_index.commit()?;
        shard_b_index.commit()?;
        drop(shard_a_index);
        drop(shard_b_index);

        crate::search::tantivy::publish_federated_searchable_index_directories(
            &published,
            &[&shard_a, &shard_b],
        )?;

        let client = SearchClient::open(&published, None)?.expect("federated index present");
        assert!(client.has_tantivy());
        assert_eq!(client.total_docs(), 4);

        let hits = client.search(
            "shared federated needle",
            SearchFilters::default(),
            10,
            0,
            FieldMask::FULL,
        )?;
        assert_eq!(hits.len(), 4);
        let observed_order = hits
            .iter()
            .map(|hit| {
                (
                    hit.source_path.clone(),
                    hit.line_number,
                    hit.content.clone(),
                    hit.score.to_bits(),
                )
            })
            .collect::<Vec<_>>();
        let hit_paths = hits
            .iter()
            .map(|hit| hit.source_path.as_str())
            .collect::<std::collections::HashSet<_>>();
        assert!(hit_paths.contains("/tmp/fed-query-a.jsonl"));
        assert!(hit_paths.contains("/tmp/fed-query-b.jsonl"));

        for attempt in 0..3 {
            let repeated = client.search(
                "shared federated needle",
                SearchFilters::default(),
                10,
                0,
                FieldMask::FULL,
            )?;
            let repeated_order = repeated
                .iter()
                .map(|hit| {
                    (
                        hit.source_path.clone(),
                        hit.line_number,
                        hit.content.clone(),
                        hit.score.to_bits(),
                    )
                })
                .collect::<Vec<_>>();
            assert_eq!(
                repeated_order, observed_order,
                "federated lexical query order drifted on repeated attempt {attempt}"
            );
        }

        Ok(())
    }

    #[test]
    fn semantic_search_session_paths_filter_retries_past_initial_candidates() -> Result<()> {
        let fixture = build_semantic_test_fixture()?;
        let mut filters = SearchFilters::default();
        filters
            .session_paths
            .insert(fixture.source_paths[2].clone());

        let (hits, ann_stats) = fixture.client.search_semantic(
            "semantic fixture query",
            filters,
            1,
            0,
            FieldMask::FULL,
            false,
        )?;

        assert!(
            ann_stats.is_none(),
            "exact search should not emit ANN stats"
        );
        assert_eq!(
            hits.len(),
            1,
            "filtered semantic search should still return a hit"
        );
        assert_eq!(
            hits[0].source_path, fixture.source_paths[2],
            "semantic search should keep searching until it finds the requested session path"
        );

        Ok(())
    }

    #[test]
    fn semantic_search_offsets_after_session_paths_filtering() -> Result<()> {
        let fixture = build_semantic_test_fixture()?;
        let mut filters = SearchFilters::default();
        filters
            .session_paths
            .insert(fixture.source_paths[1].clone());
        filters
            .session_paths
            .insert(fixture.source_paths[2].clone());

        let (hits, _) = fixture.client.search_semantic(
            "semantic fixture query",
            filters,
            1,
            1,
            FieldMask::FULL,
            false,
        )?;

        assert_eq!(
            hits.len(),
            1,
            "second filtered page should still return one hit"
        );
        assert_eq!(
            hits[0].source_path, fixture.source_paths[2],
            "offset must apply after semantic deduplication and session path filtering"
        );

        Ok(())
    }

    #[test]
    fn semantic_search_merges_sharded_vector_indexes() -> Result<()> {
        let fixture = build_sharded_semantic_test_fixture()?;
        let (hits, ann_stats) = fixture.client.search_semantic(
            "semantic fixture query",
            SearchFilters::default(),
            3,
            0,
            FieldMask::FULL,
            false,
        )?;

        assert!(
            ann_stats.is_none(),
            "sharded exact search should not emit ANN stats"
        );
        assert_eq!(hits.len(), 3);
        assert_eq!(hits[0].source_path, fixture.source_paths[0]);
        assert_eq!(hits[1].source_path, fixture.source_paths[1]);
        assert_eq!(hits[2].source_path, fixture.source_paths[2]);

        Ok(())
    }

    #[test]
    fn progressive_phase_overfetches_before_session_paths_filtering() -> Result<()> {
        let fixture = build_semantic_test_fixture()?;
        let mut filters = SearchFilters::default();
        filters
            .session_paths
            .insert(fixture.source_paths[2].clone());

        let results = vec![
            FsScoredResult {
                doc_id: fixture.doc_ids[0].clone(),
                score: 1.0,
                source: FsScoreSource::SemanticFast,
                index: None,
                fast_score: Some(1.0),
                quality_score: None,
                lexical_score: None,
                rerank_score: None,
                explanation: None,
                metadata: None,
            },
            FsScoredResult {
                doc_id: fixture.doc_ids[1].clone(),
                score: 0.9,
                source: FsScoreSource::SemanticFast,
                index: None,
                fast_score: Some(0.9),
                quality_score: None,
                lexical_score: None,
                rerank_score: None,
                explanation: None,
                metadata: None,
            },
            FsScoredResult {
                doc_id: fixture.doc_ids[2].clone(),
                score: 0.8,
                source: FsScoreSource::SemanticFast,
                index: None,
                fast_score: Some(0.8),
                quality_score: None,
                lexical_score: None,
                rerank_score: None,
                explanation: None,
                metadata: None,
            },
        ];

        let result = fixture.client.progressive_phase_to_result(
            &results,
            ProgressivePhaseContext {
                query: "session path filter",
                filters: &filters,
                field_mask: FieldMask::FULL,
                lexical_cache: None,
                limit: 1,
                fetch_limit: 3,
            },
        )?;

        assert_eq!(
            result.hits.len(),
            1,
            "progressive phase should retain enough overfetched hits to satisfy post-search session path filtering"
        );
        assert_eq!(
            result.hits[0].source_path, fixture.source_paths[2],
            "progressive phase should page after session path filtering"
        );

        Ok(())
    }

    // =============================================================================
    // SQL Placeholder Builder Tests (Opt 4.5: Pre-sized String Buffers)
    // =============================================================================

    #[test]
    fn sql_placeholders_empty() {
        assert_eq!(sql_placeholders(0), "");
    }

    #[test]
    fn sql_placeholders_single() {
        assert_eq!(sql_placeholders(1), "?");
    }

    #[test]
    fn sql_placeholders_multiple() {
        assert_eq!(sql_placeholders(3), "?,?,?");
        assert_eq!(sql_placeholders(5), "?,?,?,?,?");
    }

    #[test]
    fn sql_placeholders_capacity_efficient() {
        // For count=3, capacity should be exactly 2*3-1=5 ("?,?,?" = 5 chars)
        let result = sql_placeholders(3);
        assert_eq!(result.len(), 5);
        assert!(result.capacity() >= 5); // Should have allocated at least 5

        // For count=10, capacity should be exactly 2*10-1=19
        let result = sql_placeholders(10);
        assert_eq!(result.len(), 19);
        assert!(result.capacity() >= 19);
    }

    #[test]
    fn sql_placeholders_large_count() {
        // Test with a large count to ensure no off-by-one errors
        let result = sql_placeholders(100);
        assert_eq!(result.len(), 199); // 100 "?" + 99 ","
        assert_eq!(result.chars().filter(|c| *c == '?').count(), 100);
        assert_eq!(result.chars().filter(|c| *c == ',').count(), 99);
    }

    #[test]
    fn hybrid_budget_identifier_biases_lexical() {
        let budget = hybrid_candidate_budget("src/main.rs", 20, 20, 5, 10_000);
        assert!(
            budget.lexical_candidates > budget.semantic_candidates,
            "identifier queries should allocate more lexical than semantic fanout"
        );
        assert!(budget.lexical_candidates >= 25);
    }

    #[test]
    fn hybrid_budget_natural_language_biases_semantic() {
        let budget = hybrid_candidate_budget(
            "how do we fix authentication middleware latency",
            20,
            20,
            5,
            10_000,
        );
        assert!(
            budget.semantic_candidates > budget.lexical_candidates,
            "natural language queries should allocate more semantic than lexical fanout"
        );
    }

    #[test]
    fn hybrid_budget_no_limit_caps_both_lexical_and_semantic() {
        // Regression: a "no limit" hybrid search on a large corpus used to
        // set `lexical_candidates = total_docs`, which let a single
        // `cass search` request grow to tens of GB of RAM on a ~500k-row
        // user history and saturate disk IO. Both lexical and semantic
        // fanout are now bounded, lexical against the RAM-proportional
        // `no_limit_result_cap()` ceiling and semantic against the narrower
        // `HYBRID_NO_LIMIT_SEMANTIC_CAP` ceiling.
        let total_docs = 2_000_000;
        let budget =
            hybrid_candidate_budget("authentication middleware", 0, total_docs, 0, total_docs);
        let cap = no_limit_result_cap();
        assert!(
            budget.lexical_candidates <= cap,
            "lexical fanout must respect no_limit_result_cap() = {cap}; got {}",
            budget.lexical_candidates
        );
        assert!(
            budget.lexical_candidates <= NO_LIMIT_RESULT_MAX,
            "lexical fanout must respect the absolute NO_LIMIT_RESULT_MAX; got {}",
            budget.lexical_candidates
        );
        assert!(budget.semantic_candidates <= HYBRID_NO_LIMIT_SEMANTIC_CAP);
        // Invariant preserved by the `.min(lexical)` clamp inside
        // hybrid_candidate_budget: semantic fanout never exceeds
        // lexical fanout. On typical hosts lexical >> semantic, but
        // the cheaper `<=` assertion also holds on edge-case tiny
        // boxes where the overall cap pulls lexical down to the
        // planning window.
        assert!(
            budget.semantic_candidates <= budget.lexical_candidates,
            "semantic ({}) must not exceed lexical ({}) fanout",
            budget.semantic_candidates,
            budget.lexical_candidates
        );
    }

    #[test]
    fn compute_no_limit_result_cap_clamps_explicit_over_ceiling_env_override() {
        // A naively large explicit override must still be clamped. The
        // old implementation returned the env value unclamped, which
        // reintroduced the unbounded-result failure mode. Driven via
        // the pure `*_from` helper so we can't race with other
        // concurrent tests that read the real env.
        let cap = compute_no_limit_result_cap_from(Some("999999999999".to_string()), None, None);
        assert!(
            cap <= NO_LIMIT_RESULT_MAX,
            "explicit override must still clamp to ceiling; got {cap} > {NO_LIMIT_RESULT_MAX}"
        );
        assert!(cap >= NO_LIMIT_RESULT_MIN);
    }

    #[test]
    fn compute_no_limit_result_cap_clamps_tiny_explicit_override_up_to_floor() {
        // Mirror case: an explicit override under the floor is lifted.
        let cap = compute_no_limit_result_cap_from(Some("1".to_string()), None, None);
        assert_eq!(cap, NO_LIMIT_RESULT_MIN);
    }

    #[test]
    fn compute_no_limit_result_cap_uses_meminfo_when_no_env_override() {
        // 128 GiB available → 128 / 16 = 8 GiB budget (under the 16 GiB
        // ceiling, above the 256 MiB floor) → 8 GiB / 80 KiB ≈ 104k
        // hits. That lands inside [MIN, MAX] and above floor.
        let cap = compute_no_limit_result_cap_from(None, None, Some(128u64 * 1024 * 1024 * 1024));
        assert!(cap >= NO_LIMIT_RESULT_MIN, "cap {cap} below floor");
        assert!(cap <= NO_LIMIT_RESULT_MAX, "cap {cap} above ceiling");
        // Sanity: 128 GiB / 16 / 80 KiB is nowhere near 1k.
        assert!(cap > NO_LIMIT_RESULT_MIN * 10);
    }

    #[test]
    fn compute_no_limit_result_cap_falls_back_to_floor_when_meminfo_unavailable() {
        // Simulates non-Linux (no /proc/meminfo): must still produce a
        // finite, in-envelope cap. The floor budget (256 MiB) / 80 KiB
        // ≈ 3276 hits — above MIN, below MAX.
        let cap = compute_no_limit_result_cap_from(None, None, None);
        assert!(cap >= NO_LIMIT_RESULT_MIN);
        assert!(cap <= NO_LIMIT_RESULT_MAX);
    }

    #[test]
    fn compute_no_limit_result_cap_bytes_env_takes_priority_over_meminfo() {
        // Explicit bytes override wins over MemAvailable. 4 GiB bytes
        // / 80 KiB ≈ 52k hits, distinct from what a large MemAvailable
        // hint would otherwise produce (which would hit the 16 GiB
        // ceiling → ~209k hits).
        let four_gib = (4u64 * 1024 * 1024 * 1024).to_string();
        let cap = compute_no_limit_result_cap_from(
            None,
            Some(four_gib),
            Some(1024u64 * 1024 * 1024 * 1024), // 1 TiB (would ceiling otherwise)
        );
        let expected_hits = ((4u64 * 1024 * 1024 * 1024) / AVG_HIT_BYTES) as usize;
        let expected = expected_hits.clamp(NO_LIMIT_RESULT_MIN, NO_LIMIT_RESULT_MAX);
        assert_eq!(cap, expected, "bytes env must win over meminfo");
    }

    #[test]
    fn no_limit_budget_bytes_preserves_fallback_priority() {
        let huge_meminfo = Some(1024u64 * 1024 * 1024 * 1024);
        let four_gib = 4u64 * 1024 * 1024 * 1024;

        assert_eq!(
            no_limit_budget_bytes(Some(four_gib.to_string()), huge_meminfo),
            four_gib
        );
        assert_eq!(
            no_limit_budget_bytes(Some("0".to_string()), huge_meminfo),
            NO_LIMIT_BYTES_CEILING
        );
        assert_eq!(no_limit_budget_bytes(None, None), NO_LIMIT_BYTES_FLOOR);
    }

    #[test]
    fn compute_no_limit_result_cap_ignores_malformed_env() {
        // Garbage or zero values fall back to meminfo / floor, not crash.
        for bad in ["", "abc", "0", "-1"] {
            let cap = compute_no_limit_result_cap_from(
                Some(bad.to_string()),
                Some(bad.to_string()),
                None,
            );
            assert!(cap >= NO_LIMIT_RESULT_MIN, "bad={bad:?} cap={cap}");
            assert!(cap <= NO_LIMIT_RESULT_MAX, "bad={bad:?} cap={cap}");
        }
    }

    // =============================================================================
    // RRF (Reciprocal Rank Fusion) Tests
    // =============================================================================

    fn make_test_hit(id: &str, score: f32) -> SearchHit {
        SearchHit {
            title: id.to_string(),
            snippet: String::new(),
            content: id.to_string(),
            content_hash: stable_content_hash(id),
            score,
            source_path: format!("/path/{}.jsonl", id),
            agent: "test".to_string(),
            workspace: "/workspace".to_string(),
            workspace_original: None,
            created_at: Some(1_700_000_000_000),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".to_string(),
            origin_kind: "local".to_string(),
            origin_host: None,
            conversation_id: None,
        }
    }

    #[test]
    fn test_rrf_fusion_ordering() {
        // Test that RRF correctly combines rankings from both lists
        // Higher ranks in both lists should result in higher final ranking
        let lexical = vec![
            make_test_hit("A", 10.0),
            make_test_hit("B", 8.0),
            make_test_hit("C", 6.0),
        ];
        let semantic = vec![
            make_test_hit("A", 0.9),
            make_test_hit("B", 0.7),
            make_test_hit("D", 0.5),
        ];

        let fused = rrf_fuse_hits(&lexical, &semantic, "", 10, 0);

        // A and B should be top (in both lists), A first (rank 0 in both)
        assert_eq!(fused.len(), 4);
        assert_eq!(fused[0].title, "A"); // Rank 0 in both
        assert_eq!(fused[1].title, "B"); // Rank 1 in both
        // C and D are in only one list each, order depends on their ranks
    }

    #[test]
    fn test_rrf_handles_disjoint_sets() {
        // Test with no overlap between lexical and semantic results
        let lexical = vec![make_test_hit("A", 10.0), make_test_hit("B", 8.0)];
        let semantic = vec![make_test_hit("C", 0.9), make_test_hit("D", 0.7)];

        let fused = rrf_fuse_hits(&lexical, &semantic, "", 10, 0);

        // All 4 items should be present
        assert_eq!(fused.len(), 4);
        let titles: Vec<&str> = fused.iter().map(|h| h.title.as_str()).collect();
        assert!(titles.contains(&"A"));
        assert!(titles.contains(&"B"));
        assert!(titles.contains(&"C"));
        assert!(titles.contains(&"D"));
    }

    #[test]
    fn test_rrf_tie_breaking_deterministic() {
        // Test that results are deterministic - same input always produces same output
        let lexical = vec![
            make_test_hit("X", 5.0),
            make_test_hit("Y", 5.0),
            make_test_hit("Z", 5.0),
        ];
        let semantic = vec![]; // Empty semantic list

        // Run multiple times and verify same order
        let fused1 = rrf_fuse_hits(&lexical, &semantic, "", 10, 0);
        let fused2 = rrf_fuse_hits(&lexical, &semantic, "", 10, 0);
        let fused3 = rrf_fuse_hits(&lexical, &semantic, "", 10, 0);

        // Order should be deterministic based on key comparison
        assert_eq!(fused1.len(), fused2.len());
        assert_eq!(fused2.len(), fused3.len());

        for i in 0..fused1.len() {
            assert_eq!(fused1[i].title, fused2[i].title, "Mismatch at index {}", i);
            assert_eq!(fused2[i].title, fused3[i].title, "Mismatch at index {}", i);
        }
    }

    #[test]
    fn test_rrf_both_lists_bonus() {
        // Documents appearing in both lists should rank higher than those in only one
        // Even if their individual ranks are lower
        let lexical = vec![
            make_test_hit("solo_lex", 10.0), // Rank 0 lexical only
            make_test_hit("both", 5.0),      // Rank 1 lexical
        ];
        let semantic = vec![
            make_test_hit("solo_sem", 0.9), // Rank 0 semantic only
            make_test_hit("both", 0.5),     // Rank 1 semantic
        ];

        let fused = rrf_fuse_hits(&lexical, &semantic, "", 10, 0);

        // "both" should be first due to appearing in both lists
        // It gets RRF score from rank 1 in both lists = 1/(60+2) * 2 = 0.0322
        // vs solo items get 1/(60+1) = 0.0164 each
        assert_eq!(
            fused[0].title, "both",
            "Doc in both lists should rank first"
        );
    }

    #[test]
    fn test_rrf_respects_limit_and_offset() {
        let lexical = vec![
            make_test_hit("A", 10.0),
            make_test_hit("B", 8.0),
            make_test_hit("C", 6.0),
        ];
        let semantic = vec![];

        // Test limit
        let fused = rrf_fuse_hits(&lexical, &semantic, "", 2, 0);
        assert_eq!(fused.len(), 2);

        // Test offset
        let fused_offset = rrf_fuse_hits(&lexical, &semantic, "", 10, 1);
        assert_eq!(fused_offset.len(), 2); // Skipped first one

        // Test limit 0
        let fused_empty = rrf_fuse_hits(&lexical, &semantic, "", 0, 0);
        assert!(fused_empty.is_empty());
    }

    #[test]
    fn test_rrf_empty_inputs() {
        let empty: Vec<SearchHit> = vec![];
        let non_empty = vec![make_test_hit("A", 10.0)];

        // Both empty
        assert!(rrf_fuse_hits(&empty, &empty, "", 10, 0).is_empty());

        // Lexical empty
        let fused = rrf_fuse_hits(&empty, &non_empty, "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].title, "A");

        // Semantic empty
        let fused = rrf_fuse_hits(&non_empty, &empty, "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].title, "A");
    }

    #[test]
    fn test_rrf_coalesces_empty_title_hits_across_search_modes() {
        let mut lexical = make_test_hit("shared", 10.0);
        lexical.title.clear();
        lexical.source_path = "/shared/untitled.jsonl".into();
        lexical.content = "same untitled body".into();
        lexical.content_hash = stable_content_hash("same untitled body");

        let mut semantic = lexical.clone();
        semantic.score = 0.9;

        let fused = rrf_fuse_hits(&[lexical], &[semantic], "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].title, "");
    }

    #[test]
    fn test_rrf_coalesces_blank_local_source_id_hits_across_search_modes() {
        let mut lexical = make_test_hit("shared-local", 10.0);
        lexical.source_path = "/shared/local.jsonl".into();
        lexical.content = "same local body".into();
        lexical.content_hash = stable_content_hash("same local body");
        lexical.source_id = "local".into();
        lexical.origin_kind = "local".into();

        let mut semantic = lexical.clone();
        semantic.source_id = "   ".into();
        semantic.origin_kind = "local".into();
        semantic.score = 0.9;

        let fused = rrf_fuse_hits(&[lexical], &[semantic], "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].source_id, "local");
    }

    #[test]
    fn test_rrf_keeps_repeated_same_content_at_different_lines() {
        let mut first = make_test_hit("same", 10.0);
        first.title = "Shared Session".into();
        first.source_path = "/shared/session.jsonl".into();
        first.content = "repeat me".into();
        first.content_hash = stable_content_hash("repeat me");
        first.line_number = Some(1);
        first.created_at = Some(100);

        let mut second = first.clone();
        second.line_number = Some(2);
        second.created_at = Some(200);
        second.score = 0.9;

        let fused = rrf_fuse_hits(&[first], &[second], "", 10, 0);
        assert_eq!(fused.len(), 2);
        assert_eq!(fused[0].line_number, Some(1));
        assert_eq!(fused[1].line_number, Some(2));
    }

    #[test]
    fn test_rrf_coalesces_present_and_missing_conversation_id_for_same_message() {
        let mut lexical = make_test_hit("same", 10.0);
        lexical.title = "Shared Session".into();
        lexical.source_path = "/shared/session.jsonl".into();
        lexical.content = "identical body".into();
        lexical.content_hash = stable_content_hash("identical body");
        lexical.created_at = Some(100);
        lexical.line_number = Some(1);
        lexical.conversation_id = None;

        let mut semantic = lexical.clone();
        semantic.conversation_id = Some(42);
        semantic.score = 0.9;

        let fused = rrf_fuse_hits(&[lexical], &[semantic], "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].conversation_id, Some(42));
    }

    #[test]
    fn test_rrf_coalesces_present_and_missing_conversation_id_despite_blank_local_source_id() {
        let mut lexical = make_test_hit("same", 10.0);
        lexical.title = "Shared Session".into();
        lexical.source_path = "/shared/session.jsonl".into();
        lexical.content = "identical body".into();
        lexical.content_hash = stable_content_hash("identical body");
        lexical.created_at = Some(100);
        lexical.line_number = Some(1);
        lexical.conversation_id = None;
        lexical.source_id = "local".into();
        lexical.origin_kind = "local".into();

        let mut semantic = lexical.clone();
        semantic.conversation_id = Some(42);
        semantic.source_id = "   ".into();
        semantic.origin_kind = "local".into();
        semantic.score = 0.9;

        let fused = rrf_fuse_hits(&[lexical], &[semantic], "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].conversation_id, Some(42));
    }

    #[test]
    fn test_rrf_keeps_distinct_conversation_ids_for_shared_path_and_content() {
        let mut first = make_test_hit("same", 10.0);
        first.title = "Shared Session".into();
        first.source_path = "/shared/session.jsonl".into();
        first.content = "identical body".into();
        first.content_hash = stable_content_hash("identical body");
        first.conversation_id = Some(1);

        let mut second = first.clone();
        second.conversation_id = Some(2);
        second.score = 0.9;

        let fused = rrf_fuse_hits(&[first], &[second], "", 10, 0);
        assert_eq!(fused.len(), 2);
        assert!(fused.iter().any(|hit| hit.conversation_id == Some(1)));
        assert!(fused.iter().any(|hit| hit.conversation_id == Some(2)));
    }

    #[test]
    fn test_rrf_coalesces_same_conversation_id_despite_title_drift() {
        let mut lexical = make_test_hit("same", 10.0);
        lexical.title = "Morning Session".into();
        lexical.source_path = "/shared/session.jsonl".into();
        lexical.content = "identical body".into();
        lexical.content_hash = stable_content_hash("identical body");
        lexical.conversation_id = Some(9);

        let mut semantic = lexical.clone();
        semantic.title = "Evening Session".into();
        semantic.score = 0.9;

        let fused = rrf_fuse_hits(&[lexical], &[semantic], "", 10, 0);
        assert_eq!(fused.len(), 1);
        assert_eq!(fused[0].conversation_id, Some(9));
    }

    #[test]
    fn test_rrf_keeps_distinct_titles_for_shared_path_and_content() {
        let mut morning = make_test_hit("same", 10.0);
        morning.title = "Morning Session".into();
        morning.source_path = "/shared/session.jsonl".into();
        morning.content = "identical body".into();
        morning.content_hash = stable_content_hash("identical body");
        morning.created_at = None;

        let mut evening = morning.clone();
        evening.title = "Evening Session".into();
        evening.score = 0.9;

        let fused = rrf_fuse_hits(&[morning], &[evening], "", 10, 0);
        assert_eq!(fused.len(), 2);
        assert!(fused.iter().any(|hit| hit.title == "Morning Session"));
        assert!(fused.iter().any(|hit| hit.title == "Evening Session"));
    }

    #[test]
    fn test_rrf_candidate_depth() {
        // Test with many candidates to ensure proper fusion
        let lexical: Vec<_> = (0..50)
            .map(|i| make_test_hit(&format!("L{}", i), 100.0 - i as f32))
            .collect();
        let semantic: Vec<_> = (0..50)
            .map(|i| make_test_hit(&format!("S{}", i), 1.0 - 0.01 * i as f32))
            .collect();

        let fused = rrf_fuse_hits(&lexical, &semantic, "", 20, 0);

        // Should return 20 items
        assert_eq!(fused.len(), 20);

        // All items should be unique
        let mut seen = std::collections::HashSet::new();
        for hit in &fused {
            assert!(seen.insert(&hit.title), "Duplicate hit: {}", hit.title);
        }
    }

    // ==========================================================================
    // QueryTokenList Behavior Tests (Opt 4.4)
    // ==========================================================================

    #[test]
    fn query_token_list_parses_small_queries() {
        let cases = [
            ("hello", 1),
            ("hello world", 2),
            ("hello AND world", 3),
            ("hello world foo bar", 4),
        ];

        for (query, expected_len) in cases {
            let tokens = parse_boolean_query(query);
            assert_eq!(tokens.len(), expected_len, "{query}");
        }
    }

    #[test]
    fn query_token_list_parses_large_queries() {
        let tokens = parse_boolean_query("a b c d e f g h i");
        assert_eq!(tokens.len(), 9);
    }

    #[test]
    fn query_token_list_handles_quoted_phrases() {
        let tokens = parse_boolean_query("\"hello world\" test");
        assert_eq!(tokens.len(), 2);

        // Verify the phrase is correctly parsed
        assert!(
            matches!(&tokens[0], QueryToken::Phrase(phrase) if phrase == "hello world"),
            "Expected Phrase token"
        );
    }

    #[test]
    fn query_token_list_handles_operators() {
        let tokens = parse_boolean_query("foo AND bar OR baz");
        assert_eq!(tokens.len(), 5);
        assert_eq!(tokens[1], QueryToken::And);
        assert_eq!(tokens[3], QueryToken::Or);
    }

    #[test]
    fn query_token_list_empty_query() {
        let tokens = parse_boolean_query("");
        assert!(tokens.is_empty());
    }

    #[test]
    fn query_token_list_iteration_works() {
        let tokens = parse_boolean_query("a b c");
        let terms: Vec<_> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.as_str()),
                _ => None,
            })
            .collect();
        assert_eq!(terms, vec!["a", "b", "c"]);
    }

    // ==========================================================================
    // Unicode Query Parsing Tests (br-327c)
    // Comprehensive Unicode handling tests covering emoji, CJK, RTL, mixed
    // scripts, zero-width characters, combining characters, normalization,
    // supplementary plane characters, and bidirectional text.
    // ==========================================================================

    // --- Emoji queries ---

    #[test]
    fn unicode_emoji_treated_as_separator() {
        // Emoji are not alphanumeric per Unicode, so sanitize_query replaces them with spaces
        let sanitized = sanitize_query("🚀 launch");
        assert_eq!(sanitized, "  launch", "Emoji should become space");
    }

    #[test]
    fn unicode_emoji_splits_terms() {
        // Emoji between words acts as a separator
        let sanitized = sanitize_query("hot🔥code");
        assert_eq!(sanitized, "hot code", "Emoji between words splits them");
    }

    #[test]
    fn unicode_multiple_emoji_become_spaces() {
        let sanitized = sanitize_query("🚀🔥💻");
        assert_eq!(
            sanitized.trim(),
            "",
            "All-emoji query sanitizes to whitespace"
        );
    }

    #[test]
    fn unicode_emoji_query_parses_without_panic() {
        let tokens = parse_boolean_query("🚀 launch code 🔥");
        let terms: Vec<_> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.clone()),
                _ => None,
            })
            .collect();
        // Emoji removed by sanitization in normalize_term_parts, only words remain
        assert!(
            terms
                .iter()
                .any(|t| t.contains("launch") || t.contains("code"))
        );
    }

    #[test]
    fn unicode_emoji_query_terms_lower() {
        let terms = QueryTermsLower::from_query("🚀 LAUNCH");
        // Emoji becomes space, LAUNCH lowercased
        let tokens: Vec<&str> = terms.tokens().collect();
        assert!(
            tokens.contains(&"launch"),
            "Should extract 'launch' from emoji query"
        );
    }

    // --- CJK character queries ---

    #[test]
    fn unicode_cjk_chinese_preserved() {
        assert_eq!(sanitize_query("测试代码"), "测试代码");
        assert_eq!(sanitize_query("测试 代码"), "测试 代码");
    }

    #[test]
    fn unicode_cjk_japanese_preserved() {
        assert_eq!(sanitize_query("テスト"), "テスト");
        // Hiragana and Katakana are alphanumeric
        assert_eq!(sanitize_query("こんにちは世界"), "こんにちは世界");
    }

    #[test]
    fn unicode_cjk_korean_preserved() {
        assert_eq!(sanitize_query("테스트"), "테스트");
        assert_eq!(sanitize_query("안녕하세요"), "안녕하세요");
    }

    #[test]
    fn unicode_cjk_parsed_as_terms() {
        let tokens = parse_boolean_query("测试 代码 search");
        let terms: Vec<_> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.as_str()),
                _ => None,
            })
            .collect();
        assert_eq!(terms, vec!["测试", "代码", "search"]);
    }

    #[test]
    fn unicode_cjk_query_terms_lower() {
        let terms = QueryTermsLower::from_query("测试 代码");
        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["测试", "代码"]);
    }

    // --- RTL text queries ---

    #[test]
    fn unicode_hebrew_preserved() {
        assert_eq!(sanitize_query("שלום עולם"), "שלום עולם");
    }

    #[test]
    fn unicode_arabic_preserved() {
        assert_eq!(sanitize_query("مرحبا"), "مرحبا");
    }

    #[test]
    fn unicode_hebrew_parsed_as_terms() {
        let tokens = parse_boolean_query("שלום עולם");
        let terms: Vec<_> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.as_str()),
                _ => None,
            })
            .collect();
        assert_eq!(terms, vec!["שלום", "עולם"]);
    }

    #[test]
    fn unicode_arabic_query_terms_lower() {
        // Arabic doesn't have case, so lowercasing is a no-op
        let terms = QueryTermsLower::from_query("مرحبا بالعالم");
        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["مرحبا", "بالعالم"]);
    }

    // --- Mixed script queries ---

    #[test]
    fn unicode_mixed_scripts_preserved() {
        let sanitized = sanitize_query("Hello 世界 мир");
        assert_eq!(sanitized, "Hello 世界 мир");
    }

    #[test]
    fn unicode_mixed_scripts_parsed() {
        let tokens = parse_boolean_query("Hello 世界 мир");
        let terms: Vec<_> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.as_str()),
                _ => None,
            })
            .collect();
        assert_eq!(terms, vec!["Hello", "世界", "мир"]);
    }

    #[test]
    fn unicode_mixed_scripts_with_emoji() {
        // Emoji stripped, scripts preserved
        let sanitized = sanitize_query("Hello 🌍 世界");
        assert_eq!(sanitized, "Hello   世界");
    }

    #[test]
    fn unicode_latin_cyrillic_arabic_query() {
        let terms = QueryTermsLower::from_query("Hello Мир مرحبا");
        let tokens: Vec<&str> = terms.tokens().collect();
        assert_eq!(tokens, vec!["hello", "мир", "مرحبا"]);
    }

    // --- Zero-width characters ---

    #[test]
    fn unicode_zero_width_joiner_removed() {
        // Zero-width joiner (U+200D) is not alphanumeric → becomes space
        let sanitized = sanitize_query("test\u{200D}query");
        assert_eq!(sanitized, "test query");
    }

    #[test]
    fn unicode_zero_width_non_joiner_removed() {
        // Zero-width non-joiner (U+200C) is not alphanumeric → becomes space
        let sanitized = sanitize_query("test\u{200C}query");
        assert_eq!(sanitized, "test query");
    }

    #[test]
    fn unicode_zero_width_space_removed() {
        // Zero-width space (U+200B) is not alphanumeric → becomes space
        let sanitized = sanitize_query("test\u{200B}query");
        assert_eq!(sanitized, "test query");
    }

    #[test]
    fn unicode_bom_removed() {
        // Byte-order mark (U+FEFF) should not appear in search terms
        let sanitized = sanitize_query("\u{FEFF}test");
        assert_eq!(sanitized, " test");
    }

    // --- Combining characters ---

    #[test]
    fn unicode_precomposed_accent_preserved() {
        // Precomposed é (U+00E9) is a single letter → alphanumeric
        let sanitized = sanitize_query("café");
        assert_eq!(sanitized, "café");
    }

    #[test]
    fn unicode_combining_accent_becomes_separator() {
        // Decomposed: 'e' + combining acute accent (U+0301)
        // nfc_sanitize_query first normalizes to NFC, composing e + U+0301
        // into precomposed é (U+00E9), which is alphanumeric and preserved.
        let input = "cafe\u{0301}";
        let sanitized = sanitize_query(input);
        assert_eq!(sanitized, "caf\u{00e9}");
    }

    #[test]
    fn unicode_nfc_and_nfd_produce_same_sanitized_query() {
        // NFC (precomposed): é = U+00E9 (single char, alphanumeric)
        let nfc = "caf\u{00E9}";
        // NFD (decomposed): e + ◌́ = U+0065 U+0301 (two chars, accent not alphanumeric)
        let nfd = "cafe\u{0301}";

        let san_nfc = sanitize_query(nfc);
        let san_nfd = sanitize_query(nfd);

        // Both produce "café" because nfc_sanitize_query normalizes to NFC
        // before sanitization, matching the NFC-indexed content from
        // DefaultCanonicalizer.
        assert_eq!(san_nfc, "café");
        assert_eq!(san_nfd, "café");
        assert_eq!(san_nfc, san_nfd);
    }

    #[test]
    fn unicode_combining_marks_do_not_panic() {
        // Multiple combining marks stacked (e.g., Zalgo text)
        let zalgo = "t\u{0301}\u{0302}\u{0303}e\u{0304}\u{0305}st";
        let sanitized = sanitize_query(zalgo);
        // Should not panic; combining marks become spaces
        assert!(sanitized.contains('t'));
        assert!(sanitized.contains('s'));
    }

    // --- Supplementary plane characters (outside BMP) ---

    #[test]
    fn unicode_mathematical_bold_letters_preserved() {
        // Mathematical Bold Capital A (U+1D400) — classified as Letter
        let input = "\u{1D400}\u{1D401}\u{1D402}";
        let sanitized = sanitize_query(input);
        assert_eq!(
            sanitized, input,
            "Mathematical bold letters are alphanumeric"
        );
    }

    #[test]
    fn unicode_supplementary_ideograph_preserved() {
        // CJK Unified Ideographs Extension B character (U+20000)
        let input = "\u{20000}";
        let sanitized = sanitize_query(input);
        assert_eq!(
            sanitized, input,
            "Supplementary CJK ideographs are alphanumeric"
        );
    }

    #[test]
    fn unicode_supplementary_emoji_removed() {
        // Grinning face (U+1F600) — Symbol, not alphanumeric
        let input = "test\u{1F600}query";
        let sanitized = sanitize_query(input);
        assert_eq!(sanitized, "test query");
    }

    // --- Bidirectional text ---

    #[test]
    fn unicode_bidi_mixed_ltr_rtl_no_panic() {
        let input = "hello שלום world עולם";
        let tokens = parse_boolean_query(input);
        let terms: Vec<_> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.as_str()),
                _ => None,
            })
            .collect();
        assert_eq!(terms.len(), 4);
        assert!(terms.contains(&"hello"));
        assert!(terms.contains(&"שלום"));
        assert!(terms.contains(&"world"));
        assert!(terms.contains(&"עולם"));
    }

    #[test]
    fn unicode_bidi_override_chars_removed() {
        // Left-to-right override (U+202D) and pop directional (U+202C)
        // These are format characters, not alphanumeric
        let input = "test\u{202D}content\u{202C}end";
        let sanitized = sanitize_query(input);
        assert_eq!(sanitized, "test content end");
    }

    #[test]
    fn unicode_bidi_rtl_mark_removed() {
        // Right-to-left mark (U+200F) is not alphanumeric
        let input = "test\u{200F}content";
        let sanitized = sanitize_query(input);
        assert_eq!(sanitized, "test content");
    }

    // --- Full pipeline integration tests ---

    #[test]
    fn unicode_full_pipeline_cjk_query() {
        let explanation = QueryExplanation::analyze("测试 代码", &SearchFilters::default());
        assert_eq!(explanation.parsed.terms.len(), 2);
        assert!(!explanation.parsed.terms[0].text.is_empty());
        assert!(!explanation.parsed.terms[1].text.is_empty());
    }

    #[test]
    fn unicode_full_pipeline_mixed_script_boolean() {
        let explanation =
            QueryExplanation::analyze("Hello AND 世界 OR مرحبا", &SearchFilters::default());
        // Should parse operators correctly even with mixed scripts
        assert!(
            explanation.parsed.operators.iter().any(|op| op == "AND"),
            "AND operator should be recognized in mixed-script query"
        );
    }

    #[test]
    fn unicode_full_pipeline_emoji_query_type() {
        // An all-emoji query sanitizes to empty — should handle gracefully
        let explanation = QueryExplanation::analyze("🚀🔥💻", &SearchFilters::default());
        // Should not panic; terms may be empty after sanitization
        assert!(
            explanation.parsed.terms.is_empty()
                || explanation
                    .parsed
                    .terms
                    .iter()
                    .all(|t| t.subterms.is_empty()),
            "All-emoji query should produce no meaningful terms"
        );
    }

    #[test]
    fn unicode_full_pipeline_phrase_with_cjk() {
        let explanation = QueryExplanation::analyze("\"测试代码\"", &SearchFilters::default());
        assert!(
            !explanation.parsed.phrases.is_empty(),
            "CJK phrase should be recognized"
        );
    }

    #[test]
    fn unicode_full_pipeline_wildcard_with_unicode() {
        let explanation = QueryExplanation::analyze("*测试*", &SearchFilters::default());
        assert!(
            !explanation.parsed.terms.is_empty(),
            "Wildcard with CJK should produce terms"
        );
        // Check that the term has a substring/wildcard pattern
        if let Some(term) = explanation.parsed.terms.first() {
            assert!(
                term.subterms
                    .iter()
                    .any(|s| s.pattern.contains("*") || s.pattern == "exact"),
                "CJK wildcard should produce wildcard or exact pattern"
            );
        }
    }

    #[test]
    fn unicode_query_terms_lower_case_folding() {
        // German sharp s (ß) lowercases to ß (not ss in Rust)
        let terms = QueryTermsLower::from_query("STRAßE");
        assert_eq!(terms.query_lower, "straße");

        // Turkish dotless I (İ → i with dot below in some locales, but
        // Rust uses simple Unicode case mapping)
        let terms2 = QueryTermsLower::from_query("HELLO");
        assert_eq!(terms2.query_lower, "hello");
    }

    #[test]
    fn unicode_normalize_term_parts_cjk() {
        let parts = normalize_term_parts("测试 代码");
        assert_eq!(parts, vec!["测试", "代码"]);
    }

    #[test]
    fn unicode_normalize_term_parts_strips_emoji() {
        let parts = normalize_term_parts("🚀launch🔥code");
        // Emoji replaced with space, splitting into two terms
        assert!(parts.contains(&"launch".to_string()));
        assert!(parts.contains(&"code".to_string()));
    }

    // ── Special character query tests (br-g650) ────────────────────────────

    // Category 1: Unbalanced quotes

    #[test]
    fn special_char_unbalanced_quote_no_panic() {
        let tokens = parse_boolean_query("\"hello world");
        assert!(
            tokens
                .iter()
                .any(|t| matches!(t, QueryToken::Phrase(p) if p.contains("hello"))),
            "Unbalanced quote should still produce a phrase: {tokens:?}"
        );
    }

    #[test]
    fn special_char_unbalanced_trailing_quote() {
        let tokens = parse_boolean_query("test\"");
        assert!(
            tokens
                .iter()
                .any(|t| matches!(t, QueryToken::Term(w) if w == "test")),
            "Text before trailing quote should parse as term: {tokens:?}"
        );
    }

    #[test]
    fn special_char_multiple_unbalanced_quotes() {
        let tokens = parse_boolean_query("\"foo \"bar");
        assert!(
            !tokens.is_empty(),
            "Should parse despite odd quotes: {tokens:?}"
        );
    }

    #[test]
    fn special_char_empty_quotes() {
        let tokens = parse_boolean_query("\"\" test");
        assert!(
            tokens
                .iter()
                .any(|t| matches!(t, QueryToken::Term(w) if w == "test")),
            "Empty quotes should be skipped: {tokens:?}"
        );
    }

    #[test]
    fn special_char_unbalanced_via_sanitize() {
        let sanitized = sanitize_query("\"hello world");
        assert!(
            sanitized.contains('"'),
            "Quotes preserved by sanitize_query"
        );
    }

    // Category 2: Escaped quotes

    #[test]
    fn special_char_backslash_quote_sanitize() {
        let sanitized = sanitize_query("\\\"test\\\"");
        assert!(sanitized.contains('"'));
        assert!(!sanitized.contains('\\'), "Backslash should be stripped");
    }

    #[test]
    fn special_char_backslash_quote_parse() {
        let tokens = parse_boolean_query("\\\"test\\\"");
        assert!(!tokens.is_empty(), "Should parse without panic: {tokens:?}");
    }

    #[test]
    fn special_char_inner_escaped_quotes() {
        let tokens = parse_boolean_query("\"test \\\"inner\\\" test\"");
        assert!(
            !tokens.is_empty(),
            "Nested escaped quotes should not panic: {tokens:?}"
        );
    }

    // Category 3: Backslash sequences

    #[test]
    fn special_char_windows_path_sanitize() {
        let sanitized = sanitize_query("C:\\Users\\test");
        assert_eq!(sanitized, "C  Users test");
    }

    #[test]
    fn special_char_unc_path_sanitize() {
        let sanitized = sanitize_query("\\\\server\\share");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"server"));
        assert!(parts.contains(&"share"));
    }

    #[test]
    fn special_char_windows_path_terms() {
        let parts = normalize_term_parts("C:\\Users\\test\\file.rs");
        assert!(parts.contains(&"C".to_string()));
        assert!(parts.contains(&"Users".to_string()));
        assert!(parts.contains(&"test".to_string()));
        assert!(parts.contains(&"file".to_string()));
        assert!(parts.contains(&"rs".to_string()));
    }

    // Category 4: Regex metacharacters

    #[test]
    fn special_char_regex_dot_star() {
        let sanitized = sanitize_query("foo.*bar");
        assert_eq!(sanitized, "foo *bar");
    }

    #[test]
    fn special_char_regex_char_class() {
        let sanitized = sanitize_query("[a-z]+");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["a-z"]);
        assert_eq!(normalize_term_parts("[a-z]+"), vec!["a", "z"]);
    }

    #[test]
    fn special_char_regex_anchors() {
        let sanitized = sanitize_query("^start$");
        assert_eq!(sanitized.trim(), "start");
    }

    #[test]
    fn special_char_regex_pipe_groups() {
        let sanitized = sanitize_query("(foo|bar)");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["foo", "bar"]);
    }

    // Category 5: SQL injection patterns

    #[test]
    fn special_char_sql_injection_or() {
        let sanitized = sanitize_query("'OR 1=1--");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"OR"));
        assert!(parts.contains(&"1"));
        assert!(!sanitized.contains('\''));
        assert!(!sanitized.contains('='));
    }

    #[test]
    fn special_char_sql_injection_drop() {
        let sanitized = sanitize_query("; DROP TABLE users;--");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"DROP"));
        assert!(parts.contains(&"TABLE"));
        assert!(parts.contains(&"users"));
        assert!(!sanitized.contains(';'));
    }

    #[test]
    fn special_char_sql_injection_union() {
        let sanitized = sanitize_query("' UNION SELECT * FROM passwords --");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"UNION"));
        assert!(parts.contains(&"SELECT"));
        assert!(parts.contains(&"*"));
        assert!(parts.contains(&"FROM"));
        assert!(parts.contains(&"passwords"));
    }

    #[test]
    fn special_char_sql_parse_as_literal() {
        let tokens = parse_boolean_query("OR 1=1");
        assert!(
            tokens.iter().any(|t| matches!(t, QueryToken::Or)),
            "OR should be parsed as Or operator: {tokens:?}"
        );
    }

    // Category 6: Shell injection patterns

    #[test]
    fn special_char_shell_subshell() {
        let sanitized = sanitize_query("$(cmd)");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["cmd"]);
    }

    #[test]
    fn special_char_shell_backticks() {
        let sanitized = sanitize_query("`cmd`");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["cmd"]);
    }

    #[test]
    fn special_char_shell_pipe_rm() {
        let sanitized = sanitize_query("| rm -rf /");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"rm"));
        assert!(parts.contains(&"-rf"));
        assert_eq!(normalize_term_parts("| rm -rf /"), vec!["rm", "rf"]);
        assert!(!sanitized.contains('|'));
        assert!(!sanitized.contains('/'));
    }

    #[test]
    fn special_char_shell_semicolon_chain() {
        let sanitized = sanitize_query("test; echo pwned; cat /etc/passwd");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"test"));
        assert!(parts.contains(&"echo"));
        assert!(parts.contains(&"pwned"));
        assert!(!sanitized.contains(';'));
    }

    // Category 7: Null bytes

    #[test]
    fn special_char_null_byte_mid_string() {
        let sanitized = sanitize_query("test\x00hidden");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["test", "hidden"]);
    }

    #[test]
    fn special_char_null_byte_leading() {
        let sanitized = sanitize_query("\x00\x00attack");
        assert_eq!(sanitized.trim(), "attack");
    }

    #[test]
    fn special_char_null_byte_trailing() {
        let sanitized = sanitize_query("query\x00\x00\x00");
        assert_eq!(sanitized.trim(), "query");
    }

    #[test]
    fn special_char_null_byte_parse() {
        let tokens = parse_boolean_query("test\x00hidden");
        assert!(
            !tokens.is_empty(),
            "Null bytes should not prevent parsing: {tokens:?}"
        );
    }

    // Category 8: Control characters

    #[test]
    fn special_char_control_newline() {
        let sanitized = sanitize_query("line1\nline2");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["line1", "line2"]);
    }

    #[test]
    fn special_char_control_tab_cr() {
        let sanitized = sanitize_query("tab\there\r\nend");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["tab", "here", "end"]);
    }

    #[test]
    fn special_char_control_parse_whitespace() {
        let tokens = parse_boolean_query("hello\tworld\ntest");
        let terms: Vec<&str> = tokens
            .iter()
            .filter_map(|t| match t {
                QueryToken::Term(s) => Some(s.as_str()),
                _ => None,
            })
            .collect();
        assert_eq!(terms, vec!["hello", "world", "test"]);
    }

    #[test]
    fn special_char_control_bell_escape() {
        let sanitized = sanitize_query("test\x07\x1b[31mred");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"test"));
        assert!(parts.contains(&"31mred"));
    }

    // Category 9: HTML/XML entities

    #[test]
    fn special_char_html_entity_lt() {
        let sanitized = sanitize_query("&lt;script&gt;");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["lt", "script", "gt"]);
    }

    #[test]
    fn special_char_html_numeric_entity() {
        let sanitized = sanitize_query("&#x3C;script&#x3E;");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"x3C"));
        assert!(parts.contains(&"script"));
        assert!(parts.contains(&"x3E"));
    }

    #[test]
    fn special_char_html_tags_stripped() {
        let sanitized = sanitize_query("<script>alert('xss')</script>");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"script"));
        assert!(parts.contains(&"alert"));
        assert!(parts.contains(&"xss"));
    }

    #[test]
    fn special_char_html_attribute() {
        let sanitized = sanitize_query("<img src=\"evil.js\" onerror=\"alert(1)\">");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert!(parts.contains(&"img"));
        assert!(parts.contains(&"src"));
        assert!(parts.contains(&"onerror"));
    }

    // Category 10: URL encoding

    #[test]
    fn special_char_url_percent_encoding() {
        let sanitized = sanitize_query("%20space%2Fslash");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["20space", "2Fslash"]);
    }

    #[test]
    fn special_char_url_null_byte_encoded() {
        let sanitized = sanitize_query("test%00hidden");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["test", "00hidden"]);
    }

    #[test]
    fn special_char_url_full_query_string() {
        let sanitized = sanitize_query("search?q=hello&lang=en");
        let parts: Vec<&str> = sanitized.split_whitespace().collect();
        assert_eq!(parts, vec!["search", "q", "hello", "lang", "en"]);
    }

    // Cross-cutting: full pipeline integration

    #[test]
    fn special_char_explain_sql_injection() {
        let filters = SearchFilters::default();
        let explanation = QueryExplanation::analyze("'OR 1=1--", &filters);
        assert!(
            !explanation.parsed.terms.is_empty() || !explanation.parsed.phrases.is_empty(),
            "SQL injection should produce parseable terms"
        );
    }

    #[test]
    fn special_char_explain_shell_injection() {
        let filters = SearchFilters::default();
        let explanation = QueryExplanation::analyze("$(rm -rf /)", &filters);
        assert!(
            !explanation.parsed.terms.is_empty(),
            "Shell injection should produce parseable terms"
        );
    }

    #[test]
    fn special_char_explain_html_xss() {
        let filters = SearchFilters::default();
        let explanation = QueryExplanation::analyze("<script>alert('xss')</script>", &filters);
        assert!(
            !explanation.parsed.terms.is_empty(),
            "XSS payload should produce parseable terms"
        );
    }

    #[test]
    fn special_char_terms_lower_injection() {
        let qt = QueryTermsLower::from_query("'; DROP TABLE--");
        let tokens: Vec<&str> = qt.tokens().collect();
        for token in &tokens {
            assert!(
                token.chars().all(|c| c.is_alphanumeric()),
                "Token should only contain alphanumeric characters: {token}"
            );
        }
    }

    #[test]
    fn special_char_terms_lower_null_bytes() {
        let qt = QueryTermsLower::from_query("test\x00hidden");
        let tokens: Vec<&str> = qt.tokens().collect();
        assert!(tokens.contains(&"test"));
        assert!(tokens.contains(&"hidden"));
    }

    #[test]
    fn special_char_boolean_with_injection() {
        let tokens = parse_boolean_query("search AND 'OR 1=1-- NOT drop");
        assert!(
            tokens.iter().any(|t| matches!(t, QueryToken::And)),
            "Boolean AND should still be recognized: {tokens:?}"
        );
        assert!(
            tokens.iter().any(|t| matches!(t, QueryToken::Not)),
            "Boolean NOT should still be recognized: {tokens:?}"
        );
    }

    // ==========================================================================
    // Query Length Stress Tests (coding_agent_session_search-z1bk)
    // Tests for extreme input sizes to ensure parser robustness.
    // ==========================================================================

    #[test]
    fn stress_query_100k_chars_completes_quickly() {
        // 100k character query - must complete in <1 second
        let long_query = "a ".repeat(50000);
        assert_eq!(long_query.len(), 100000);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&long_query);
        let elapsed_sanitize = start.elapsed();

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&sanitized);
        let elapsed_parse = start.elapsed();

        assert!(
            elapsed_sanitize < std::time::Duration::from_secs(1),
            "sanitize_query with 100k chars took {:?} (>1s)",
            elapsed_sanitize
        );
        assert!(
            elapsed_parse < std::time::Duration::from_secs(1),
            "parse_boolean_query with 100k chars took {:?} (>1s)",
            elapsed_parse
        );
        assert!(!tokens.is_empty(), "100k char query should produce tokens");
    }

    #[test]
    fn stress_query_1000_terms() {
        // 1000 space-separated words
        let words: Vec<String> = (0..1000).map(|i| format!("word{}", i)).collect();
        let query = words.join(" ");

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&query);
        let tokens = parse_boolean_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "1000 terms query took {:?} (>1s)",
            elapsed
        );
        // Should have roughly 1000 Term tokens
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert!(
            term_count >= 900,
            "Expected ~1000 terms, got {} terms",
            term_count
        );
    }

    #[test]
    fn stress_query_1000_identical_terms() {
        // Same word repeated 1000 times
        let query = "test ".repeat(1000);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&query);
        let tokens = parse_boolean_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "1000 identical terms query took {:?} (>1s)",
            elapsed
        );

        // Verify parse_boolean_query produced expected tokens
        let parsed_term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert_eq!(parsed_term_count, 1000, "Parser should produce 1000 terms");

        // QueryTermsLower should handle this efficiently
        let qt = QueryTermsLower::from_query(&query);
        let tokens_lower: Vec<&str> = qt.tokens().collect();
        assert_eq!(
            tokens_lower.len(),
            1000,
            "All 1000 identical terms should be preserved"
        );
        assert!(
            tokens_lower.iter().all(|t| *t == "test"),
            "All tokens should be 'test'"
        );
    }

    #[test]
    fn stress_query_10k_char_single_term() {
        // 10k character single continuous string (no spaces)
        let long_term = "a".repeat(10000);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&long_term);
        let tokens = parse_boolean_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "10k char single term took {:?} (>1s)",
            elapsed
        );
        assert_eq!(tokens.len(), 1, "Should produce exactly one token");
        assert!(
            matches!(&tokens[0], QueryToken::Term(t) if t.len() == 10000),
            "Expected Term token"
        );
    }

    #[test]
    fn stress_deeply_nested_parentheses() {
        // 100+ levels of nested parentheses (though parser doesn't use them,
        // they become spaces and shouldn't cause issues)
        let open_parens = "(".repeat(100);
        let close_parens = ")".repeat(100);
        let query = format!("{}test{}", open_parens, close_parens);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&query);
        let tokens = parse_boolean_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_millis(100),
            "Deeply nested parens took {:?} (>100ms)",
            elapsed
        );
        // Parentheses become spaces, leaving just "test"
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert_eq!(term_count, 1, "Should have 1 term after sanitizing parens");
    }

    #[test]
    fn stress_many_boolean_operators() {
        // 100+ boolean operators: "a AND b AND c AND ..."
        let terms: Vec<String> = (0..101).map(|i| format!("term{}", i)).collect();
        let query = terms.join(" AND ");

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&query);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "100+ boolean ops took {:?} (>1s)",
            elapsed
        );

        let and_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::And))
            .count();
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();

        assert_eq!(and_count, 100, "Should have 100 AND operators");
        assert_eq!(term_count, 101, "Should have 101 terms");
    }

    #[test]
    fn stress_many_or_operators() {
        // 100+ OR operators: "a OR b OR c OR ..."
        let terms: Vec<String> = (0..101).map(|i| format!("opt{}", i)).collect();
        let query = terms.join(" OR ");

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&query);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "100+ OR ops took {:?} (>1s)",
            elapsed
        );

        let or_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Or))
            .count();
        assert_eq!(or_count, 100, "Should have 100 OR operators");
    }

    #[test]
    fn stress_mixed_boolean_operators() {
        // Complex query with many mixed operators
        let query = "a AND b OR c NOT d AND e OR f NOT g ".repeat(50);

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&query);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "Mixed boolean ops took {:?} (>1s)",
            elapsed
        );
        assert!(
            !tokens.is_empty(),
            "Complex boolean query should produce tokens"
        );
    }

    #[test]
    fn stress_memory_bounds_large_query() {
        // Verify no excessive memory allocation with large input
        // We can't easily measure memory in a unit test, but we can verify
        // the output size is reasonable relative to input.
        let large_query = "x".repeat(100000);

        let sanitized = sanitize_query(&large_query);
        let tokens = parse_boolean_query(&sanitized);

        // Sanitized output shouldn't be larger than input
        assert!(
            sanitized.len() <= large_query.len(),
            "Sanitized output should not exceed input size"
        );

        // Should produce exactly 1 token
        assert_eq!(tokens.len(), 1);

        // QueryTermsLower internal storage should be bounded
        let qt = QueryTermsLower::from_query(&large_query);
        let token_count = qt.tokens().count();
        assert_eq!(token_count, 1, "Should be 1 token of 100k chars");
    }

    #[test]
    fn stress_concurrent_queries() {
        use std::thread;

        let queries: Vec<String> = (0..100)
            .map(|i| format!("concurrent_query_{} test search", i))
            .collect();

        let handles: Vec<_> = queries
            .into_iter()
            .map(|query| {
                thread::spawn(move || {
                    let sanitized = sanitize_query(&query);
                    let tokens = parse_boolean_query(&sanitized);
                    let qt = QueryTermsLower::from_query(&query);
                    (tokens.len(), qt.tokens().count())
                })
            })
            .collect();

        for (i, handle) in handles.into_iter().enumerate() {
            let (token_len, qt_len) = handle.join().expect("Thread panicked");
            assert!(token_len > 0, "Query {} should produce tokens", i);
            assert!(qt_len > 0, "Query {} QueryTermsLower should have tokens", i);
        }
    }

    #[test]
    fn stress_many_quoted_phrases() {
        // 50 quoted phrases
        let phrases: Vec<String> = (0..50)
            .map(|i| format!("\"phrase number {}\"", i))
            .collect();
        let query = phrases.join(" AND ");

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&query);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "50 quoted phrases took {:?} (>1s)",
            elapsed
        );

        let phrase_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Phrase(_)))
            .count();
        assert_eq!(phrase_count, 50, "Should have 50 phrases");
    }

    #[test]
    fn stress_alternating_quotes() {
        // Alternating quoted and unquoted: "a" b "c" d "e" ...
        let parts: Vec<String> = (0..100)
            .map(|i| {
                if i % 2 == 0 {
                    format!("\"word{}\"", i)
                } else {
                    format!("word{}", i)
                }
            })
            .collect();
        let query = parts.join(" ");

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&query);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "100 alternating quotes took {:?} (>1s)",
            elapsed
        );

        let phrase_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Phrase(_)))
            .count();
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();

        assert_eq!(phrase_count, 50, "Should have 50 phrases");
        assert_eq!(term_count, 50, "Should have 50 terms");
    }

    #[test]
    fn stress_many_wildcards() {
        // Many wildcard patterns
        let patterns: Vec<&str> = vec!["pre*", "*suf", "*sub*", "a*b", "test*", "*ing", "*tion*"];
        let query = patterns
            .iter()
            .cycle()
            .take(100)
            .cloned()
            .collect::<Vec<_>>()
            .join(" ");

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&query);
        let tokens = parse_boolean_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "100 wildcards took {:?} (>1s)",
            elapsed
        );
        assert!(!tokens.is_empty());
    }

    #[test]
    fn stress_query_explanation_large_query() {
        // Test QueryExplanation with a large query
        let words: Vec<String> = (0..100).map(|i| format!("term{}", i)).collect();
        let query = words.join(" ");
        let filters = SearchFilters::default();

        let start = std::time::Instant::now();
        let explanation = QueryExplanation::analyze(&query, &filters);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(2),
            "QueryExplanation for 100 terms took {:?} (>2s)",
            elapsed
        );
        assert!(
            !explanation.parsed.terms.is_empty(),
            "Should parse terms successfully"
        );
    }

    #[test]
    fn stress_very_long_single_quoted_phrase() {
        // Single quoted phrase with many words
        let words: Vec<String> = (0..500).map(|i| format!("word{}", i)).collect();
        let phrase = format!("\"{}\"", words.join(" "));

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&phrase);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "500-word phrase took {:?} (>1s)",
            elapsed
        );

        let phrase_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Phrase(_)))
            .count();
        assert_eq!(phrase_count, 1, "Should have exactly 1 phrase");
    }

    #[test]
    fn stress_not_prefix_many() {
        // Many NOT prefixes: -a -b -c -d ...
        let terms: Vec<String> = (0..100).map(|i| format!("-term{}", i)).collect();
        let query = terms.join(" ");

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&query);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "100 NOT prefixes took {:?} (>1s)",
            elapsed
        );

        let not_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Not))
            .count();
        assert_eq!(not_count, 100, "Should have 100 NOT operators");
    }

    #[test]
    fn stress_unicode_large_cjk_query() {
        // Large CJK query (each char is alphanumeric)
        let cjk_chars = "中文日本語한국어".repeat(1000);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&cjk_chars);
        let qt = QueryTermsLower::from_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "Large CJK query took {:?} (>1s)",
            elapsed
        );
        assert!(!qt.is_empty(), "CJK query should produce tokens");
    }

    #[test]
    fn stress_unicode_many_emoji() {
        // Query with many emoji (non-alphanumeric, become spaces)
        let emoji_query = "🚀 🔍 📝 💻 🎯 ".repeat(500);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&emoji_query);
        let tokens = parse_boolean_query(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "Emoji query took {:?} (>1s)",
            elapsed
        );
        // Emoji are stripped, leaving empty
        assert!(
            tokens.is_empty(),
            "Emoji-only query should produce no tokens"
        );
    }

    #[test]
    fn stress_mixed_content_large() {
        // Mixed content: code, prose, symbols, unicode
        let mixed = r#"
            function test() { return x + y; }
            SELECT * FROM users WHERE id = 1;
            The quick brown fox 狐狸 jumps over lazy dog
            Error: "undefined is not a function" at line 42
            https://example.com/path?query=value&other=123
        "#
        .repeat(100);

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&mixed);
        let tokens = parse_boolean_query(&sanitized);
        let qt = QueryTermsLower::from_query(&mixed);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(2),
            "Mixed content query took {:?} (>2s)",
            elapsed
        );
        assert!(!tokens.is_empty());
        assert!(!qt.is_empty());
    }

    // ==========================================================================
    // Query Parser Unit Tests (br-335y) - Unicode, Special Chars, Edge Cases
    // ==========================================================================

    // --- Unicode queries with emoji in terms ---

    #[test]
    fn unicode_emoji_mixed_with_alphanumeric() {
        // Emoji surrounded by alphanumeric text
        let tokens = parse_boolean_query("rocket🚀launch");
        assert_eq!(tokens.len(), 1);
        // sanitize_query strips emoji (non-alphanumeric), so this becomes "rocket launch"
        let sanitized = sanitize_query("rocket🚀launch");
        assert_eq!(sanitized, "rocket launch");

        // Multiple emoji between words
        let sanitized2 = sanitize_query("test🔥🎯code");
        assert_eq!(sanitized2, "test  code");
    }

    #[test]
    fn unicode_emoji_with_boolean_operators() {
        // AND/OR/NOT with queries containing emoji
        let tokens = parse_boolean_query("🚀code AND test");
        // After parsing, we should have 3 tokens (emoji becomes space/empty)
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert!(term_count >= 1, "Should have at least one term");

        // OR with emoji
        let tokens_or = parse_boolean_query("deploy OR 🎯target");
        let has_or = tokens_or.iter().any(|t| matches!(t, QueryToken::Or));
        assert!(has_or, "Should detect OR operator");
    }

    #[test]
    fn unicode_emoji_at_word_boundaries() {
        // Emoji at start of query
        let sanitized_start = sanitize_query("🔍search");
        assert_eq!(sanitized_start, " search");

        // Emoji at end of query
        let sanitized_end = sanitize_query("complete✅");
        assert_eq!(sanitized_end, "complete ");

        // Only emoji - becomes empty
        let sanitized_only = sanitize_query("🎉🎊🎁");
        assert!(
            sanitized_only.trim().is_empty(),
            "Emoji-only should be empty after trimming"
        );
    }

    // --- RTL (Right-to-Left) text: Arabic and Hebrew ---

    #[test]
    fn unicode_arabic_text_preserved() {
        // Arabic text should be preserved as alphanumeric
        let arabic = "مرحبا بالعالم"; // "Hello World" in Arabic
        let sanitized = sanitize_query(arabic);
        assert_eq!(
            sanitized, arabic,
            "Arabic alphanumeric chars should be preserved"
        );

        let tokens = parse_boolean_query(arabic);
        assert!(!tokens.is_empty(), "Arabic query should produce tokens");
    }

    #[test]
    fn unicode_hebrew_text_preserved() {
        // Hebrew text should be preserved
        let hebrew = "שלום עולם"; // "Hello World" in Hebrew
        let sanitized = sanitize_query(hebrew);
        assert_eq!(
            sanitized, hebrew,
            "Hebrew alphanumeric chars should be preserved"
        );

        let tokens = parse_boolean_query(hebrew);
        assert!(!tokens.is_empty(), "Hebrew query should produce tokens");
    }

    #[test]
    fn unicode_mixed_rtl_and_ltr() {
        // Mixed RTL (Arabic) and LTR (English) text
        let mixed = "hello مرحبا world";
        let sanitized = sanitize_query(mixed);
        assert_eq!(sanitized, mixed, "Mixed RTL/LTR should be preserved");

        let tokens = parse_boolean_query(mixed);
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert_eq!(term_count, 3, "Should have 3 terms");
    }

    #[test]
    fn unicode_rtl_with_boolean_operators() {
        // Hebrew with AND operator
        let hebrew_and = "שלום AND עולם";
        let tokens = parse_boolean_query(hebrew_and);
        let has_and = tokens.iter().any(|t| matches!(t, QueryToken::And));
        assert!(has_and, "Should detect AND operator in Hebrew query");

        // Arabic with NOT operator
        let arabic_not = "مرحبا NOT بالعالم";
        let tokens_not = parse_boolean_query(arabic_not);
        let has_not = tokens_not.iter().any(|t| matches!(t, QueryToken::Not));
        assert!(has_not, "Should detect NOT operator in Arabic query");
    }

    // --- Backslash handling ---

    #[test]
    fn special_chars_backslash_stripped() {
        // Backslash is not alphanumeric, so it becomes space
        let query = r"path\to\file";
        let sanitized = sanitize_query(query);
        assert_eq!(sanitized, "path to file");
    }

    #[test]
    fn special_chars_escaped_quotes_handling() {
        // Backslash before quote - backslash stripped, quote preserved
        let query = r#"say \"hello\""#;
        let sanitized = sanitize_query(query);
        // Backslash becomes space, quotes preserved
        assert!(sanitized.contains('"'), "Quotes should be preserved");
    }

    #[test]
    fn special_chars_windows_paths() {
        // Windows-style paths with backslashes
        let path = r"C:\Users\test\Documents";
        let sanitized = sanitize_query(path);
        assert_eq!(sanitized, "C  Users test Documents");
    }

    // --- Nested/Complex boolean operators ---

    #[test]
    fn boolean_deeply_nested_operators() {
        // Complex nested expression (parser treats this as linear)
        let query = "a AND b OR c NOT d AND e";
        let tokens = parse_boolean_query(query);

        let mut and_count = 0;
        let mut or_count = 0;
        let mut not_count = 0;
        for token in &tokens {
            match token {
                QueryToken::And => and_count += 1,
                QueryToken::Or => or_count += 1,
                QueryToken::Not => not_count += 1,
                _ => {}
            }
        }

        assert_eq!(and_count, 2, "Should have 2 AND operators");
        assert_eq!(or_count, 1, "Should have 1 OR operator");
        assert_eq!(not_count, 1, "Should have 1 NOT operator");
    }

    #[test]
    fn boolean_consecutive_operators_degenerate() {
        // Consecutive operators: "AND AND" - second AND becomes a term
        let tokens = parse_boolean_query("foo AND AND bar");
        // "AND" as the final part of "AND AND" is treated as operator, then next "bar" is term
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert!(
            term_count >= 2,
            "Should have at least 2 terms (foo and bar)"
        );
    }

    #[test]
    fn boolean_operator_at_start() {
        // Operator at start of query
        let tokens = parse_boolean_query("AND foo");
        let has_and = tokens.iter().any(|t| matches!(t, QueryToken::And));
        assert!(has_and, "Leading AND should be detected");

        let tokens_or = parse_boolean_query("OR test");
        let has_or = tokens_or.iter().any(|t| matches!(t, QueryToken::Or));
        assert!(has_or, "Leading OR should be detected");
    }

    #[test]
    fn boolean_operator_at_end() {
        // Operator at end of query
        let tokens = parse_boolean_query("foo AND");
        let has_and = tokens.iter().any(|t| matches!(t, QueryToken::And));
        assert!(has_and, "Trailing AND should be detected");
    }

    // --- Numeric-only queries ---

    #[test]
    fn numeric_query_digits_only() {
        // Query with only digits
        let tokens = parse_boolean_query("12345");
        assert_eq!(tokens.len(), 1);
        assert_eq!(tokens[0], QueryToken::Term("12345".to_string()));

        let sanitized = sanitize_query("12345");
        assert_eq!(sanitized, "12345");
    }

    #[test]
    fn numeric_query_with_text() {
        // Mixed numeric and text
        let tokens = parse_boolean_query("error 404 not found");
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        // "404", "error", "found" are terms, "not" is NOT operator
        assert!(term_count >= 3, "Should have at least 3 terms");
    }

    #[test]
    fn numeric_versions_with_dots() {
        // Version numbers like "1.2.3"
        let sanitized = sanitize_query("version 1.2.3");
        assert_eq!(sanitized, "version 1 2 3"); // dots become spaces
    }

    // --- Tab and newline handling ---

    #[test]
    fn whitespace_tabs_treated_as_separators() {
        let tokens = parse_boolean_query("foo\tbar\tbaz");
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert_eq!(term_count, 3, "Tabs should separate terms");
    }

    #[test]
    fn whitespace_newlines_treated_as_separators() {
        let tokens = parse_boolean_query("foo\nbar\nbaz");
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert_eq!(term_count, 3, "Newlines should separate terms");
    }

    #[test]
    fn whitespace_mixed_types() {
        let tokens = parse_boolean_query("a \t b \n c   d");
        let term_count = tokens
            .iter()
            .filter(|t| matches!(t, QueryToken::Term(_)))
            .count();
        assert_eq!(term_count, 4, "Mixed whitespace should separate properly");
    }

    // --- Very long single terms (no spaces) ---

    #[test]
    fn stress_very_long_single_term() {
        // Single term with 10K characters (no spaces)
        let long_term = "a".repeat(10_000);

        let start = std::time::Instant::now();
        let tokens = parse_boolean_query(&long_term);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "10K char term took {:?} (>1s)",
            elapsed
        );
        assert_eq!(tokens.len(), 1);
        assert!(
            matches!(tokens.first(), Some(QueryToken::Term(t)) if t.len() == 10_000),
            "Expected 10K Term token, got {tokens:?}"
        );
    }

    #[test]
    fn stress_very_long_term_with_wildcard() {
        // Long term with wildcard suffix
        let long_pattern = format!("{}*", "prefix".repeat(1000));

        let start = std::time::Instant::now();
        let sanitized = sanitize_query(&long_pattern);
        let pattern = WildcardPattern::parse(&sanitized);
        let elapsed = start.elapsed();

        assert!(
            elapsed < std::time::Duration::from_secs(1),
            "Long wildcard pattern took {:?} (>1s)",
            elapsed
        );
        assert!(
            matches!(pattern, WildcardPattern::Prefix(_)),
            "Should parse as prefix pattern"
        );
    }

    // --- QueryExplanation edge cases ---

    #[test]
    fn query_explanation_empty_query() {
        let explanation = QueryExplanation::analyze("", &SearchFilters::default());
        assert_eq!(explanation.query_type, QueryType::Empty);
    }

    #[test]
    fn search_mode_default_is_hybrid_preferred() {
        assert_eq!(SearchMode::default(), SearchMode::Hybrid);
    }

    #[test]
    fn query_explanation_whitespace_only_query() {
        let explanation = QueryExplanation::analyze("   \t\n  ", &SearchFilters::default());
        assert_eq!(explanation.query_type, QueryType::Empty);
    }

    #[test]
    fn query_explanation_unicode_query() {
        let explanation = QueryExplanation::analyze("日本語 search", &SearchFilters::default());
        // Should classify as Simple (no operators, multiple terms = implicit AND)
        assert!(!explanation.parsed.terms.is_empty());
    }

    // --- QueryTermsLower edge cases ---

    #[test]
    fn query_terms_lower_unicode_normalization() {
        // Accented characters should be lowercased properly
        let terms = QueryTermsLower::from_query("CAFÉ RÉSUMÉ");
        assert_eq!(terms.query_lower, "café résumé");
    }

    #[test]
    fn query_terms_lower_mixed_case_unicode() {
        // Mixed case CJK and Latin
        let terms = QueryTermsLower::from_query("Hello日本語World");
        // CJK chars have no case, Latin chars should be lowercased
        assert!(terms.query_lower.contains("hello"));
        assert!(terms.query_lower.contains("world"));
    }

    #[test]
    fn query_terms_lower_preserves_numbers() {
        let terms = QueryTermsLower::from_query("ABC123XYZ");
        assert_eq!(terms.query_lower, "abc123xyz");
    }

    // --- WildcardPattern edge cases ---

    #[test]
    fn wildcard_pattern_internal_asterisk() {
        // Internal wildcard: f*o
        let pattern = WildcardPattern::parse("f*o");
        assert!(
            matches!(pattern, WildcardPattern::Complex(_)),
            "Internal asterisk should be Complex"
        );
    }

    #[test]
    fn wildcard_pattern_multiple_internal_asterisks() {
        // Multiple internal wildcards: a*b*c
        let pattern = WildcardPattern::parse("a*b*c");
        assert!(
            matches!(pattern, WildcardPattern::Complex(_)),
            "Multiple internal asterisks should be Complex"
        );
    }

    #[test]
    fn wildcard_pattern_regex_escapes_special_chars() {
        // Pattern with regex-special characters
        let pattern = WildcardPattern::parse("*foo.bar*");
        if let Some(regex) = pattern.to_regex() {
            assert!(
                regex.contains("\\."),
                "Dot should be escaped in regex: {}",
                regex
            );
        }
    }

    #[test]
    fn wildcard_pattern_complex_regex_generation() {
        let pattern = WildcardPattern::parse("f*o*o");
        if let Some(regex) = pattern.to_regex() {
            // Should handle internal wildcards
            assert!(
                regex.contains(".*"),
                "Should have .* for internal wildcards: {}",
                regex
            );
        }
    }

    #[test]
    fn test_transpile_to_fts5() {
        // Simple terms
        assert_eq!(
            transpile_to_fts5("foo bar"),
            Some("foo AND bar".to_string())
        );

        // Boolean operators
        assert_eq!(
            transpile_to_fts5("foo AND bar"),
            Some("foo AND bar".to_string())
        );
        assert_eq!(
            transpile_to_fts5("foo OR bar"),
            Some("(foo OR bar)".to_string())
        );
        assert_eq!(transpile_to_fts5("OR foo"), Some("foo".to_string()));
        assert_eq!(transpile_to_fts5("NOT foo"), None);

        // Precedence: OR binds tighter than AND in our parser logic
        // "A AND B OR C" -> "A AND (B OR C)"
        assert_eq!(
            transpile_to_fts5("A AND B OR C"),
            Some("A AND (B OR C)".to_string())
        );

        // "A OR B AND C" -> "(A OR B) AND C"
        assert_eq!(
            transpile_to_fts5("A OR B AND C"),
            Some("(A OR B) AND C".to_string())
        );

        // "A OR B OR C" -> "(A OR B OR C)"
        assert_eq!(
            transpile_to_fts5("A OR B OR C"),
            Some("(A OR B OR C)".to_string())
        );

        // Phrases
        assert_eq!(
            transpile_to_fts5("\"foo bar\""),
            Some("\"foo bar\"".to_string())
        );

        // Wildcards (allowed trailing)
        assert_eq!(transpile_to_fts5("foo*"), Some("foo*".to_string()));

        // Unsupported wildcards (leading/internal)
        assert_eq!(transpile_to_fts5("*foo"), None);
        assert_eq!(transpile_to_fts5("f*o"), None);

        // SQLite FTS5's porter tokenizer splits punctuation into separate
        // fragments, so fallback queries must do the same.
        assert_eq!(
            transpile_to_fts5("foo-bar"),
            Some("(foo AND bar)".to_string())
        );
        assert_eq!(
            transpile_to_fts5("foo-bar*"),
            Some("(foo AND bar*)".to_string())
        );
        assert_eq!(
            transpile_to_fts5("br-123.jsonl"),
            Some("(br AND 123 AND jsonl)".to_string())
        );
        assert_eq!(
            transpile_to_fts5("br-123.json*"),
            Some("(br AND 123 AND json*)".to_string())
        );

        // Leading unary-NOT forms are not valid FTS5 queries.
        assert_eq!(transpile_to_fts5("NOT A OR B"), None);
    }

    #[test]
    fn semantic_doc_id_roundtrip_from_query() {
        let hash_hex = "00".repeat(32);
        let doc_id = format!("m|42|2|3|7|11|1|1700000000000|{hash_hex}");
        let parsed = parse_semantic_doc_id(&doc_id).expect("roundtrip parse");
        assert_eq!(parsed.message_id, 42);
        assert_eq!(parsed.chunk_idx, 2);
        assert_eq!(parsed.agent_id, 3);
        assert_eq!(parsed.workspace_id, 7);
        assert_eq!(parsed.source_id, 11);
        assert_eq!(parsed.role, 1);
        assert_eq!(parsed.created_at_ms, 1_700_000_000_000);
    }

    #[test]
    fn semantic_filter_applies_all_constraints() {
        use frankensearch::core::filter::SearchFilter;

        let filter = SemanticFilter {
            agents: Some(HashSet::from([3])),
            workspaces: Some(HashSet::from([7])),
            sources: Some(HashSet::from([11])),
            roles: Some(HashSet::from([1])),
            created_from: Some(1_700_000_000_000),
            created_to: Some(1_700_000_000_100),
        };

        assert!(filter.matches("m|42|2|3|7|11|1|1700000000001", None));
        assert!(!filter.matches("m|42|2|99|7|11|1|1700000000001", None));
        assert!(!filter.matches("m|42|2|3|7|11|1|1699999999999", None));
        assert!(!filter.matches("not-a-doc-id", None));
    }

    #[test]
    fn fs_semantic_index_runs_filtered_search() -> Result<()> {
        let temp = TempDir::new()?;
        let index_path = crate::search::vector_index::vector_index_path(temp.path(), "embed-fast");
        if let Some(parent) = index_path.parent() {
            std::fs::create_dir_all(parent)?;
        }

        let hash_a = "00".repeat(32);
        let hash_b = "11".repeat(32);
        let doc_a = format!("m|101|0|1|10|100|1|1700000000001|{hash_a}");
        let doc_b = format!("m|202|0|2|20|200|1|1700000000002|{hash_b}");

        let mut writer = VectorIndex::create_with_revision(
            &index_path,
            "embed-fast",
            "rev-1",
            2,
            frankensearch::index::Quantization::F16,
        )
        .map_err(|err| anyhow!("create fsvi index failed: {err}"))?;
        writer
            .write_record(&doc_a, &[1.0, 0.0])
            .map_err(|err| anyhow!("write_record failed: {err}"))?;
        writer
            .write_record(&doc_b, &[0.0, 1.0])
            .map_err(|err| anyhow!("write_record failed: {err}"))?;
        writer
            .finish()
            .map_err(|err| anyhow!("finish fsvi index failed: {err}"))?;

        let fs_index =
            VectorIndex::open(&index_path).map_err(|err| anyhow!("open fsvi failed: {err}"))?;
        let filter = SemanticFilter {
            agents: Some(HashSet::from([1])),
            workspaces: None,
            sources: None,
            roles: None,
            created_from: None,
            created_to: None,
        };
        let fs_filter = semantic_filter_as_search_filter(&filter).expect("expected active filter");
        let hits = fs_index
            .search_top_k(&[1.0, 0.0], 5, Some(fs_filter))
            .map_err(|err| anyhow!("frankensearch search failed: {err}"))?;
        assert_eq!(hits.len(), 1);
        let parsed = parse_semantic_doc_id(&hits[0].doc_id).expect("parse bridged doc_id");
        assert_eq!(parsed.message_id, 101);
        assert_eq!(parsed.agent_id, 1);
        Ok(())
    }

    // Regression guard for bead coding_agent_session_search-q6xf9
    // (`cass search --fields minimal` silently returned zero hits even when
    // matches existed). Root cause: the dedup pass called `hit_is_noise`,
    // which fell through to `is_search_noise_text("")` when both `content`
    // and `snippet` were stripped by the field_mask — treating every
    // projection-only hit as tool/acknowledgement noise and dropping it.
    //
    // Fix: when both fields are empty because the caller explicitly
    // requested a minimal projection, we cannot classify noise from text
    // alone. Default to "not noise" and let the hit through so downstream
    // field filtering emits the requested subset.
    #[test]
    fn hit_is_noise_returns_false_when_content_and_snippet_both_empty() {
        let hit = SearchHit {
            title: String::new(),
            snippet: String::new(),
            content: String::new(),
            content_hash: 0,
            conversation_id: Some(1),
            score: 1.0,
            source_path: "/tmp/session.jsonl".to_string(),
            agent: "codex".to_string(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(1700000000000),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".to_string(),
            origin_kind: "local".to_string(),
            origin_host: None,
        };

        // Query text doesn't matter — the point is that a hit stripped of
        // content+snippet by --fields minimal must survive the noise filter
        // so `cass search --fields minimal` returns the projection.
        assert!(
            !hit_is_noise(&hit, "anything"),
            "hit with empty content AND snippet (projection-only) must NOT be classified as noise"
        );
        assert!(
            !hit_is_noise(&hit, ""),
            "noise classifier must not treat an empty-query projection-only hit as noise"
        );
    }

    // Complementary guard: make sure the noise filter still flags legitimate
    // empty rows (no content_hash, etc.) when the content is actually empty
    // because the underlying message was empty — we don't want this fix to
    // re-introduce tool-ack noise into projection-full outputs.
    #[test]
    fn hit_is_noise_still_drops_tool_acknowledgement_when_content_present() {
        let hit = SearchHit {
            title: String::new(),
            snippet: String::new(),
            content: "ok".to_string(),
            content_hash: 0,
            conversation_id: Some(1),
            score: 1.0,
            source_path: "/tmp/session.jsonl".to_string(),
            agent: "codex".to_string(),
            workspace: String::new(),
            workspace_original: None,
            created_at: Some(1700000000000),
            line_number: Some(1),
            match_type: MatchType::Exact,
            source_id: "local".to_string(),
            origin_kind: "local".to_string(),
            origin_host: None,
        };

        assert!(
            hit_is_noise(&hit, ""),
            "bare tool-ack 'ok' with content present should still be dropped as noise"
        );
    }
}