mempal-store-sqlite 0.9.0

use std::collections::{BTreeSet, VecDeque};
use std::fs;
use std::path::{Path, PathBuf};
use std::sync::OnceLock;
use std::time::{SystemTime, UNIX_EPOCH};

use mempal_agent_memory::anchor;
use mempal_agent_memory::types::{
    AnchorKind, ChunkNeighbors, Drawer, ExplicitTunnel, KnowledgeCard, KnowledgeCardEvent,
    KnowledgeCardFilter, KnowledgeEventType, KnowledgeEvidenceLink, KnowledgeEvidenceRole,
    KnowledgeStatus, KnowledgeTier, MemoryDomain, MemoryKind, NeighborChunk, Provenance,
    ReindexSource, RuntimeAdoptionEvent, RuntimeAdoptionFilter, RuntimeAdoptionSignal,
    RuntimeAdoptionTrack, SourceType, TaxonomyEntry, Triple, TripleStats, TunnelEndpoint,
    TunnelFollowResult,
};
use mempal_search_core::build_fts_match_query;
use rusqlite::{Connection, OptionalExtension, Row, params};
use serde_json::Value;
use sha2::{Digest, Sha256};
use thiserror::Error;

pub const CURRENT_SCHEMA_VERSION: u32 = 9;
const DRAWER_SELECT_COLUMNS: &str = r#"
    id,
    content,
    wing,
    room,
    source_file,
    source_type,
    added_at,
    chunk_index,
    normalize_version,
    COALESCE(importance, 0) as importance,
    memory_kind,
    domain,
    field,
    anchor_kind,
    anchor_id,
    parent_anchor_id,
    provenance,
    statement,
    tier,
    status,
    supporting_refs,
    counterexample_refs,
    teaching_refs,
    verification_refs,
    scope_constraints,
    trigger_hints
"#;

const V1_SCHEMA_SQL: &str = r#"
PRAGMA foreign_keys = ON;

CREATE TABLE IF NOT EXISTS drawers (
    id TEXT PRIMARY KEY,
    content TEXT NOT NULL,
    wing TEXT NOT NULL,
    room TEXT,
    source_file TEXT,
    source_type TEXT NOT NULL CHECK(source_type IN ('project', 'conversation', 'manual')),
    added_at TEXT NOT NULL,
    chunk_index INTEGER
);

-- drawer_vectors is created lazily by insert_vector() with the actual
-- embedding dimension from the configured embedder. This avoids hardcoding
-- a dimension that may not match the model in use.

CREATE TABLE IF NOT EXISTS triples (
    id TEXT PRIMARY KEY,
    subject TEXT NOT NULL,
    predicate TEXT NOT NULL,
    object TEXT NOT NULL,
    valid_from TEXT,
    valid_to TEXT,
    confidence REAL DEFAULT 1.0,
    source_drawer TEXT REFERENCES drawers(id)
);

CREATE TABLE IF NOT EXISTS taxonomy (
    wing TEXT NOT NULL,
    room TEXT NOT NULL DEFAULT '',
    display_name TEXT,
    keywords TEXT,
    PRIMARY KEY (wing, room)
);

CREATE INDEX IF NOT EXISTS idx_drawers_wing ON drawers(wing);
CREATE INDEX IF NOT EXISTS idx_drawers_wing_room ON drawers(wing, room);
CREATE INDEX IF NOT EXISTS idx_triples_subject ON triples(subject);
CREATE INDEX IF NOT EXISTS idx_triples_object ON triples(object);
"#;

static SQLITE_VEC_AUTO_EXTENSION: OnceLock<Result<(), String>> = OnceLock::new();

fn current_timestamp() -> String {
    match SystemTime::now().duration_since(UNIX_EPOCH) {
        Ok(duration) => duration.as_secs().to_string(),
        Err(_) => "0".to_string(),
    }
}

fn build_tunnel_id(left: &TunnelEndpoint, right: &TunnelEndpoint) -> String {
    let mut endpoints = [tunnel_endpoint_key(left), tunnel_endpoint_key(right)];
    endpoints.sort();

    let mut hasher = Sha256::new();
    for component in [
        endpoints[0].0.as_str(),
        endpoints[0].1.as_str(),
        endpoints[1].0.as_str(),
        endpoints[1].1.as_str(),
    ] {
        hasher.update([0]);
        hasher.update(component.as_bytes());
    }
    let digest = format!("{:x}", hasher.finalize());
    format!("tunnel_{}", &digest[..16])
}

fn tunnel_endpoint_key(endpoint: &TunnelEndpoint) -> (String, String) {
    (
        endpoint.wing.trim().to_string(),
        endpoint
            .room
            .as_deref()
            .map(str::trim)
            .filter(|room| !room.is_empty())
            .unwrap_or("")
            .to_string(),
    )
}

fn format_tunnel_endpoint(endpoint: &TunnelEndpoint) -> String {
    match endpoint.room.as_deref() {
        Some(room) if !room.is_empty() => format!("{}:{room}", endpoint.wing),
        _ => endpoint.wing.clone(),
    }
}

#[derive(Debug, Error)]
pub enum DbError {
    #[error("failed to create database directory for {path}")]
    CreateDir {
        path: PathBuf,
        #[source]
        source: std::io::Error,
    },
    #[error("failed to read database metadata for {path}")]
    Metadata {
        path: PathBuf,
        #[source]
        source: std::io::Error,
    },
    #[error(transparent)]
    Sqlite(#[from] rusqlite::Error),
    #[error("failed to parse taxonomy keywords JSON")]
    Json(#[from] serde_json::Error),
    #[error("invalid source_type stored in database: {0}")]
    InvalidSourceType(String),
    #[error("invalid {kind} stored in database: {value}")]
    InvalidEnumValue { kind: &'static str, value: String },
    #[error("invalid drawer metadata: {0}")]
    InvalidDrawerMetadata(String),
    #[error("invalid tunnel: {0}")]
    InvalidTunnel(String),
    #[error("failed to register sqlite-vec auto extension: {0}")]
    RegisterVec(String),
    #[error("database schema version {current} is newer than supported version {supported}")]
    UnsupportedSchemaVersion { current: u32, supported: u32 },
}

pub struct Database {
    conn: Connection,
    path: PathBuf,
}

impl Database {
    pub fn open(path: &Path) -> Result<Self, DbError> {
        if let Some(parent) = path
            .parent()
            .filter(|parent| !parent.as_os_str().is_empty())
        {
            fs::create_dir_all(parent).map_err(|source| DbError::CreateDir {
                path: parent.to_path_buf(),
                source,
            })?;
        }

        register_sqlite_vec()?;

        let conn = Connection::open(path)?;
        conn.execute_batch("PRAGMA foreign_keys = ON;")?;
        apply_migrations(&conn)?;

        Ok(Self {
            conn,
            path: path.to_path_buf(),
        })
    }

    pub fn conn(&self) -> &Connection {
        &self.conn
    }

    pub fn path(&self) -> &Path {
        &self.path
    }

    pub fn insert_drawer(&self, drawer: &Drawer) -> Result<bool, DbError> {
        anchor::validate_anchor_domain(&drawer.domain, &drawer.anchor_kind)
            .map_err(|message| DbError::InvalidDrawerMetadata(message.to_string()))?;

        let inserted = self.conn.execute(
            r#"
            INSERT INTO drawers (
                id,
                content,
                wing,
                room,
                source_file,
                source_type,
                added_at,
                chunk_index,
                normalize_version,
                importance,
                memory_kind,
                domain,
                field,
                anchor_kind,
                anchor_id,
                parent_anchor_id,
                provenance,
                statement,
                tier,
                status,
                supporting_refs,
                counterexample_refs,
                teaching_refs,
                verification_refs,
                scope_constraints,
                trigger_hints
            )
            VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12, ?13, ?14, ?15, ?16, ?17, ?18, ?19, ?20, ?21, ?22, ?23, ?24, ?25, ?26)
            ON CONFLICT(id) DO NOTHING
            "#,
            params![
                drawer.id.as_str(),
                drawer.content.as_str(),
                drawer.wing.as_str(),
                drawer.room.as_deref(),
                drawer.source_file.as_deref(),
                source_type_as_str(&drawer.source_type),
                drawer.added_at.as_str(),
                drawer.chunk_index,
                i64::from(drawer.normalize_version),
                drawer.importance,
                memory_kind_as_str(&drawer.memory_kind),
                memory_domain_as_str(&drawer.domain),
                drawer.field.as_str(),
                anchor_kind_as_str(&drawer.anchor_kind),
                drawer.anchor_id.as_str(),
                drawer.parent_anchor_id.as_deref(),
                drawer.provenance.as_ref().map(provenance_as_str),
                drawer.statement.as_deref(),
                drawer.tier.as_ref().map(knowledge_tier_as_str),
                drawer.status.as_ref().map(knowledge_status_as_str),
                encode_json(&drawer.supporting_refs)?,
                encode_json(&drawer.counterexample_refs)?,
                encode_json(&drawer.teaching_refs)?,
                encode_json(&drawer.verification_refs)?,
                drawer.scope_constraints.as_deref(),
                encode_optional_json(drawer.trigger_hints.as_ref())?,
            ],
        )?;

        Ok(inserted == 1)
    }

    pub fn taxonomy_entries(&self) -> Result<Vec<TaxonomyEntry>, DbError> {
        let mut statement = self.conn.prepare(
            "SELECT wing, room, display_name, keywords FROM taxonomy ORDER BY wing, room",
        )?;
        let rows = statement.query_map([], |row| {
            Ok((
                row.get::<_, String>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, Option<String>>(2)?,
                row.get::<_, Option<String>>(3)?,
            ))
        })?;

        let mut entries = Vec::new();
        for row in rows {
            let (wing, room, display_name, keywords_json) = row?;
            let keywords = parse_keywords(keywords_json.as_deref())?;
            entries.push(TaxonomyEntry {
                wing,
                room,
                display_name,
                keywords,
            });
        }

        Ok(entries)
    }

    pub fn upsert_taxonomy_entry(&self, entry: &TaxonomyEntry) -> Result<(), DbError> {
        let keywords = serde_json::to_string(&entry.keywords)?;
        self.conn.execute(
            r#"
            INSERT INTO taxonomy (wing, room, display_name, keywords)
            VALUES (?1, ?2, ?3, ?4)
            ON CONFLICT(wing, room) DO UPDATE SET
                display_name = excluded.display_name,
                keywords = excluded.keywords
            "#,
            (
                entry.wing.as_str(),
                entry.room.as_str(),
                entry.display_name.as_deref(),
                keywords.as_str(),
            ),
        )?;

        Ok(())
    }

    /// Returns top drawers sorted by importance (descending), then recency.
    pub fn top_drawers(&self, limit: usize) -> Result<Vec<Drawer>, DbError> {
        let limit = i64::try_from(limit)
            .map_err(|_| rusqlite::Error::InvalidParameterName("limit".to_string()))?;
        let mut statement = self.conn.prepare(&format!(
            r#"
            SELECT {DRAWER_SELECT_COLUMNS}
            FROM drawers
            WHERE deleted_at IS NULL
            ORDER BY importance DESC, CAST(added_at AS INTEGER) DESC, id DESC
            LIMIT ?1
            "#,
        ))?;
        let rows = statement.query_map([limit], |row| {
            drawer_from_row(row).map_err(row_decode_error)
        })?;

        let mut drawers = Vec::new();
        for row in rows {
            drawers.push(row?);
        }

        Ok(drawers)
    }

    pub fn drawer_exists(&self, drawer_id: &str) -> Result<bool, DbError> {
        let exists = self.conn.query_row(
            "SELECT EXISTS(SELECT 1 FROM drawers WHERE id = ?1 AND deleted_at IS NULL)",
            [drawer_id],
            |row| row.get::<_, i64>(0),
        )?;
        Ok(exists == 1)
    }

    pub fn insert_vector(&self, drawer_id: &str, vector: &[f32]) -> Result<(), DbError> {
        self.ensure_vectors_table(vector.len())?;
        let vector_json = serde_json::to_string(vector)?;
        self.conn.execute(
            "INSERT INTO drawer_vectors (id, embedding) VALUES (?1, vec_f32(?2))",
            (drawer_id, vector_json.as_str()),
        )?;
        Ok(())
    }

    pub fn upsert_drawer_and_replace_vector(
        &self,
        drawer: &Drawer,
        vector: &[f32],
    ) -> Result<(), DbError> {
        anchor::validate_anchor_domain(&drawer.domain, &drawer.anchor_kind)
            .map_err(|message| DbError::InvalidDrawerMetadata(message.to_string()))?;
        self.ensure_vectors_table(vector.len())?;

        let existing = self
            .conn
            .query_row(
                "SELECT rowid, content FROM drawers WHERE id = ?1 AND deleted_at IS NULL",
                [drawer.id.as_str()],
                |row| Ok((row.get::<_, i64>(0)?, row.get::<_, String>(1)?)),
            )
            .optional()?;

        if existing.is_none() {
            if self.insert_drawer(drawer)? {
                return self.insert_vector(&drawer.id, vector);
            }
            return Ok(());
        }

        let (rowid, old_content) = existing.expect("checked Some");
        let vector_json = serde_json::to_string(vector)?;

        self.conn.execute_batch("BEGIN IMMEDIATE;")?;
        let result = (|| -> Result<(), DbError> {
            if self.table_exists("drawers_fts")? {
                self.conn.execute(
                    "INSERT INTO drawers_fts(drawers_fts, rowid, content) VALUES ('delete', ?1, ?2)",
                    params![rowid, old_content],
                )?;
            }

            self.conn.execute(
                r#"
                UPDATE drawers
                SET content = ?2,
                    wing = ?3,
                    room = ?4,
                    source_file = ?5,
                    source_type = ?6,
                    added_at = ?7,
                    chunk_index = ?8,
                    normalize_version = ?9,
                    importance = ?10,
                    memory_kind = ?11,
                    domain = ?12,
                    field = ?13,
                    anchor_kind = ?14,
                    anchor_id = ?15,
                    parent_anchor_id = ?16,
                    provenance = ?17,
                    statement = ?18,
                    tier = ?19,
                    status = ?20,
                    supporting_refs = ?21,
                    counterexample_refs = ?22,
                    teaching_refs = ?23,
                    verification_refs = ?24,
                    scope_constraints = ?25,
                    trigger_hints = ?26
                WHERE id = ?1 AND deleted_at IS NULL
                "#,
                params![
                    drawer.id.as_str(),
                    drawer.content.as_str(),
                    drawer.wing.as_str(),
                    drawer.room.as_deref(),
                    drawer.source_file.as_deref(),
                    source_type_as_str(&drawer.source_type),
                    drawer.added_at.as_str(),
                    drawer.chunk_index,
                    i64::from(drawer.normalize_version),
                    drawer.importance,
                    memory_kind_as_str(&drawer.memory_kind),
                    memory_domain_as_str(&drawer.domain),
                    drawer.field.as_str(),
                    anchor_kind_as_str(&drawer.anchor_kind),
                    drawer.anchor_id.as_str(),
                    drawer.parent_anchor_id.as_deref(),
                    drawer.provenance.as_ref().map(provenance_as_str),
                    drawer.statement.as_deref(),
                    drawer.tier.as_ref().map(knowledge_tier_as_str),
                    drawer.status.as_ref().map(knowledge_status_as_str),
                    encode_json(&drawer.supporting_refs)?,
                    encode_json(&drawer.counterexample_refs)?,
                    encode_json(&drawer.teaching_refs)?,
                    encode_json(&drawer.verification_refs)?,
                    drawer.scope_constraints.as_deref(),
                    encode_optional_json(drawer.trigger_hints.as_ref())?,
                ],
            )?;

            if self.table_exists("drawers_fts")? {
                self.conn.execute(
                    "INSERT INTO drawers_fts(rowid, content) VALUES (?1, ?2)",
                    params![rowid, drawer.content.as_str()],
                )?;
            }

            self.conn.execute(
                "DELETE FROM drawer_vectors WHERE id = ?1",
                [drawer.id.as_str()],
            )?;
            self.conn.execute(
                "INSERT INTO drawer_vectors (id, embedding) VALUES (?1, vec_f32(?2))",
                params![drawer.id.as_str(), vector_json.as_str()],
            )?;

            Ok(())
        })();

        match result {
            Ok(()) => {
                self.conn.execute_batch("COMMIT;")?;
                Ok(())
            }
            Err(error) => {
                let _ = self.conn.execute_batch("ROLLBACK;");
                Err(error)
            }
        }
    }

    /// Ensure drawer_vectors table exists with the right dimension.
    /// Creates it on first call; errors on dimension mismatch.
    fn ensure_vectors_table(&self, dim: usize) -> Result<(), DbError> {
        // Check if table exists
        let exists: bool = self
            .conn
            .query_row(
                "SELECT EXISTS(SELECT 1 FROM sqlite_master WHERE type='table' AND name='drawer_vectors')",
                [],
                |row| row.get(0),
            )?;

        if !exists {
            self.conn.execute_batch(&format!(
                "CREATE VIRTUAL TABLE IF NOT EXISTS drawer_vectors USING vec0(id TEXT PRIMARY KEY, embedding FLOAT[{dim}]);"
            ))?;
        }
        Ok(())
    }

    pub fn drawer_count(&self) -> Result<i64, DbError> {
        Ok(self.conn.query_row(
            "SELECT COUNT(*) FROM drawers WHERE deleted_at IS NULL",
            [],
            |row| row.get(0),
        )?)
    }

    pub fn stale_drawer_count(&self, current_normalize_version: u32) -> Result<i64, DbError> {
        Ok(self.conn.query_row(
            "SELECT COUNT(*) FROM drawers WHERE deleted_at IS NULL AND normalize_version < ?1",
            [i64::from(current_normalize_version)],
            |row| row.get(0),
        )?)
    }

    pub fn drawer_count_by_normalize_version(&self) -> Result<Vec<(u32, i64)>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT normalize_version, COUNT(*)
            FROM drawers
            WHERE deleted_at IS NULL
            GROUP BY normalize_version
            ORDER BY normalize_version
            "#,
        )?;
        let rows = statement
            .query_map([], |row| Ok((row.get::<_, u32>(0)?, row.get::<_, i64>(1)?)))?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn diary_rollup_days(&self) -> Result<u32, DbError> {
        let count = self.conn.query_row(
            r#"
            SELECT COUNT(DISTINCT substr(source_file, length(source_file) - 9, 10))
            FROM drawers
            WHERE deleted_at IS NULL
              AND wing = 'agent-diary'
              AND source_file LIKE 'agent-diary://rollup/%'
            "#,
            [],
            |row| row.get::<_, i64>(0),
        )?;
        Ok(count as u32)
    }

    pub fn reindex_sources_stale(
        &self,
        current_normalize_version: u32,
    ) -> Result<Vec<ReindexSource>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT source_file, wing, room, COUNT(*)
            FROM drawers
            WHERE deleted_at IS NULL AND normalize_version < ?1
            GROUP BY source_file, wing, room
            ORDER BY source_file, wing, room
            "#,
        )?;
        let rows = statement
            .query_map(
                [i64::from(current_normalize_version)],
                reindex_source_from_row,
            )?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn reindex_sources_force(&self) -> Result<Vec<ReindexSource>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT source_file, wing, room, COUNT(*)
            FROM drawers
            WHERE deleted_at IS NULL
            GROUP BY source_file, wing, room
            ORDER BY source_file, wing, room
            "#,
        )?;
        let rows = statement
            .query_map([], reindex_source_from_row)?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    /// Hard-delete the active drawers for a source scoped to a specific room
    /// (NULL room matches NULL room), removing their FTS and vector rows too.
    ///
    /// Use this when the caller knows the exact room the drawers live in.
    /// For reindex, prefer [`replace_active_source_drawers_across_rooms`]:
    /// re-ingesting a physical source may re-route it to a different room, and
    /// a room-scoped delete would miss the stale drawers in the old room and
    /// leave duplicates behind.
    pub fn replace_active_source_drawers(
        &self,
        source_file: &str,
        wing: &str,
        room: Option<&str>,
    ) -> Result<u64, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT rowid, id, content
            FROM drawers
            WHERE deleted_at IS NULL
              AND source_file = ?1
              AND wing = ?2
              AND ((?3 IS NULL AND room IS NULL) OR room = ?3)
            ORDER BY rowid
            "#,
        )?;
        let rows = statement
            .query_map((source_file, wing, room), |row| {
                Ok((
                    row.get::<_, i64>(0)?,
                    row.get::<_, String>(1)?,
                    row.get::<_, String>(2)?,
                ))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        drop(statement);

        self.delete_source_drawer_rows(rows)
    }

    /// Hard-delete the active drawers for a source across ALL rooms in a wing.
    ///
    /// This is the correct replace semantics for reindex: a physical source
    /// file maps to one logical source, so re-indexing it should keep only the
    /// freshly produced drawers regardless of which room each previous version
    /// was routed into. Without this, a source that auto-routes to a new room
    /// on reindex leaves its old-room drawers behind as duplicates.
    pub fn replace_active_source_drawers_across_rooms(
        &self,
        source_file: &str,
        wing: &str,
    ) -> Result<u64, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT rowid, id, content
            FROM drawers
            WHERE deleted_at IS NULL
              AND source_file = ?1
              AND wing = ?2
            ORDER BY rowid
            "#,
        )?;
        let rows = statement
            .query_map((source_file, wing), |row| {
                Ok((
                    row.get::<_, i64>(0)?,
                    row.get::<_, String>(1)?,
                    row.get::<_, String>(2)?,
                ))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        drop(statement);

        self.delete_source_drawer_rows(rows)
    }

    /// Transactionally hard-delete the given (rowid, id, content) drawer rows
    /// along with their FTS and vector entries. Shared by the room-scoped and
    /// across-rooms source replacement paths.
    fn delete_source_drawer_rows(&self, rows: Vec<(i64, String, String)>) -> Result<u64, DbError> {
        if rows.is_empty() {
            return Ok(0);
        }

        self.conn.execute_batch("BEGIN IMMEDIATE;")?;
        let result = (|| -> Result<u64, DbError> {
            let fts_exists = self.table_exists("drawers_fts")?;
            let vectors_exist = self.table_exists("drawer_vectors")?;

            for (rowid, id, content) in &rows {
                if fts_exists {
                    self.conn.execute(
                        "INSERT INTO drawers_fts(drawers_fts, rowid, content) VALUES ('delete', ?1, ?2)",
                        params![rowid, content],
                    )?;
                }
                if vectors_exist {
                    self.conn
                        .execute("DELETE FROM drawer_vectors WHERE id = ?1", [id])?;
                }
                // triples.source_drawer is a FK to drawers(id) (RESTRICT). Drop
                // the dangling provenance link before the hard delete, otherwise
                // deleting a drawer referenced by a KG triple fails with a
                // FOREIGN KEY constraint error. The triple (a KG fact) is kept;
                // only its stale source pointer is cleared.
                self.conn.execute(
                    "UPDATE triples SET source_drawer = NULL WHERE source_drawer = ?1",
                    [id],
                )?;
                self.conn
                    .execute("DELETE FROM drawers WHERE rowid = ?1", [rowid])?;
            }

            Ok(rows.len() as u64)
        })();

        match result {
            Ok(count) => {
                self.conn.execute_batch("COMMIT;")?;
                Ok(count)
            }
            Err(error) => {
                let _ = self.conn.execute_batch("ROLLBACK;");
                Err(error)
            }
        }
    }

    fn table_exists(&self, table_name: &str) -> Result<bool, DbError> {
        let exists = self.conn.query_row(
            "SELECT EXISTS(SELECT 1 FROM sqlite_master WHERE type='table' AND name = ?1)",
            [table_name],
            |row| row.get::<_, i64>(0),
        )?;
        Ok(exists == 1)
    }

    pub fn taxonomy_count(&self) -> Result<i64, DbError> {
        Ok(self
            .conn
            .query_row("SELECT COUNT(*) FROM taxonomy", [], |row| row.get(0))?)
    }

    pub fn scope_counts(&self) -> Result<Vec<(String, Option<String>, i64)>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT wing, room, COUNT(*)
            FROM drawers
            WHERE deleted_at IS NULL
            GROUP BY wing, room
            ORDER BY wing, room
            "#,
        )?;
        let rows = statement
            .query_map([], |row| {
                Ok((
                    row.get::<_, String>(0)?,
                    row.get::<_, Option<String>>(1)?,
                    row.get::<_, i64>(2)?,
                ))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    /// Per-field counts for the P106 distill signal: active evidence drawers and
    /// active promoted-or-canonical knowledge drawers, grouped by `field`.
    /// Read-only; performs no writes.
    pub fn distill_field_counts(&self) -> Result<Vec<(String, i64, i64)>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT field,
                   SUM(CASE WHEN memory_kind = 'evidence' THEN 1 ELSE 0 END) AS evidence_count,
                   SUM(CASE WHEN memory_kind = 'knowledge'
                             AND status IN ('promoted', 'canonical') THEN 1 ELSE 0 END) AS promoted_count
            FROM drawers
            WHERE deleted_at IS NULL
            GROUP BY field
            "#,
        )?;
        let rows = statement
            .query_map([], |row| {
                Ok((
                    row.get::<_, String>(0)?,
                    row.get::<_, i64>(1)?,
                    row.get::<_, i64>(2)?,
                ))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    /// Up to `limit` active evidence drawer ids for a `field`, ordered by rowid
    /// for deterministic sampling. Read-only; performs no writes.
    pub fn sample_evidence_drawer_ids(
        &self,
        field: &str,
        limit: usize,
    ) -> Result<Vec<String>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT id
            FROM drawers
            WHERE deleted_at IS NULL AND memory_kind = 'evidence' AND field = ?1
            ORDER BY rowid
            LIMIT ?2
            "#,
        )?;
        let rows = statement
            .query_map(params![field, limit as i64], |row| row.get::<_, String>(0))?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn get_drawer(&self, drawer_id: &str) -> Result<Option<Drawer>, DbError> {
        let mut statement = self.conn.prepare(&format!(
            r#"
            SELECT {DRAWER_SELECT_COLUMNS}
            FROM drawers
            WHERE id = ?1 AND deleted_at IS NULL
            "#,
        ))?;
        let mut rows = statement.query_map([drawer_id], |row| {
            drawer_from_row(row).map_err(row_decode_error)
        })?;

        match rows.next() {
            Some(row) => Ok(Some(row?)),
            None => Ok(None),
        }
    }

    pub fn update_knowledge_lifecycle(
        &self,
        drawer_id: &str,
        status: &KnowledgeStatus,
        verification_refs: &[String],
        counterexample_refs: &[String],
    ) -> Result<bool, DbError> {
        let affected = self.conn.execute(
            r#"
            UPDATE drawers
            SET status = ?2,
                verification_refs = ?3,
                counterexample_refs = ?4
            WHERE id = ?1
              AND deleted_at IS NULL
              AND memory_kind = 'knowledge'
            "#,
            params![
                drawer_id,
                knowledge_status_as_str(status),
                encode_json(verification_refs)?,
                encode_json(counterexample_refs)?,
            ],
        )?;
        Ok(affected > 0)
    }

    pub fn update_knowledge_anchor(
        &self,
        drawer_id: &str,
        anchor_kind: &AnchorKind,
        anchor_id: &str,
        parent_anchor_id: Option<&str>,
    ) -> Result<bool, DbError> {
        let affected = self.conn.execute(
            r#"
            UPDATE drawers
            SET anchor_kind = ?2,
                anchor_id = ?3,
                parent_anchor_id = ?4
            WHERE id = ?1
              AND deleted_at IS NULL
              AND memory_kind = 'knowledge'
            "#,
            params![
                drawer_id,
                anchor_kind_as_str(anchor_kind),
                anchor_id,
                parent_anchor_id,
            ],
        )?;
        Ok(affected > 0)
    }

    pub fn insert_knowledge_card(&self, card: &KnowledgeCard) -> Result<(), DbError> {
        anchor::validate_anchor_domain(&card.domain, &card.anchor_kind)
            .map_err(|message| DbError::InvalidDrawerMetadata(message.to_string()))?;

        self.conn.execute(
            r#"
            INSERT INTO knowledge_cards (
                id,
                statement,
                content,
                tier,
                status,
                domain,
                field,
                anchor_kind,
                anchor_id,
                parent_anchor_id,
                scope_constraints,
                trigger_hints,
                created_at,
                updated_at
            )
            VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12, ?13, ?14)
            "#,
            params![
                card.id.as_str(),
                card.statement.as_str(),
                card.content.as_str(),
                knowledge_tier_as_str(&card.tier),
                knowledge_status_as_str(&card.status),
                memory_domain_as_str(&card.domain),
                card.field.as_str(),
                anchor_kind_as_str(&card.anchor_kind),
                card.anchor_id.as_str(),
                card.parent_anchor_id.as_deref(),
                card.scope_constraints.as_deref(),
                encode_optional_json(card.trigger_hints.as_ref())?,
                card.created_at.as_str(),
                card.updated_at.as_str(),
            ],
        )?;
        Ok(())
    }

    pub fn get_knowledge_card(&self, card_id: &str) -> Result<Option<KnowledgeCard>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT
                id,
                statement,
                content,
                tier,
                status,
                domain,
                field,
                anchor_kind,
                anchor_id,
                parent_anchor_id,
                scope_constraints,
                trigger_hints,
                created_at,
                updated_at
            FROM knowledge_cards
            WHERE id = ?1
            "#,
        )?;
        let mut rows = statement.query_map([card_id], |row| {
            knowledge_card_from_row(row).map_err(row_decode_error)
        })?;

        match rows.next() {
            Some(row) => Ok(Some(row?)),
            None => Ok(None),
        }
    }

    pub fn list_knowledge_cards(
        &self,
        filter: &KnowledgeCardFilter,
    ) -> Result<Vec<KnowledgeCard>, DbError> {
        let tier = filter.tier.as_ref().map(knowledge_tier_as_str);
        let status = filter.status.as_ref().map(knowledge_status_as_str);
        let domain = filter.domain.as_ref().map(memory_domain_as_str);
        let anchor_kind = filter.anchor_kind.as_ref().map(anchor_kind_as_str);

        let mut statement = self.conn.prepare(
            r#"
            SELECT
                id,
                statement,
                content,
                tier,
                status,
                domain,
                field,
                anchor_kind,
                anchor_id,
                parent_anchor_id,
                scope_constraints,
                trigger_hints,
                created_at,
                updated_at
            FROM knowledge_cards
            WHERE (?1 IS NULL OR tier = ?1)
              AND (?2 IS NULL OR status = ?2)
              AND (?3 IS NULL OR domain = ?3)
              AND (?4 IS NULL OR field = ?4)
              AND (?5 IS NULL OR anchor_kind = ?5)
              AND (?6 IS NULL OR anchor_id = ?6)
            ORDER BY tier, status, id
            "#,
        )?;
        let rows = statement
            .query_map(
                params![
                    tier,
                    status,
                    domain,
                    filter.field.as_deref(),
                    anchor_kind,
                    filter.anchor_id.as_deref(),
                ],
                |row| knowledge_card_from_row(row).map_err(row_decode_error),
            )?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn knowledge_card_count(&self) -> Result<i64, DbError> {
        self.conn
            .query_row("SELECT COUNT(*) FROM knowledge_cards", [], |row| row.get(0))
            .map_err(Into::into)
    }

    pub fn insert_runtime_adoption_event(
        &self,
        event: &RuntimeAdoptionEvent,
    ) -> Result<(), DbError> {
        self.conn.execute(
            r#"
            INSERT INTO runtime_adoption_events (
                id,
                track,
                signal,
                feature,
                query,
                context_hash,
                card_id,
                evaluator_id,
                research_report_id,
                note,
                metadata,
                created_at
            )
            VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12)
            "#,
            params![
                event.id.as_str(),
                runtime_adoption_track_as_str(&event.track),
                runtime_adoption_signal_as_str(&event.signal),
                event.feature.as_str(),
                event.query.as_deref(),
                event.context_hash.as_deref(),
                event.card_id.as_deref(),
                event.evaluator_id.as_deref(),
                event.research_report_id.as_deref(),
                event.note.as_deref(),
                encode_optional_json(event.metadata.as_ref())?,
                event.created_at.as_str(),
            ],
        )?;
        Ok(())
    }

    pub fn list_runtime_adoption_events(
        &self,
        filter: &RuntimeAdoptionFilter,
        limit: usize,
    ) -> Result<Vec<RuntimeAdoptionEvent>, DbError> {
        let track = filter.track.as_ref().map(runtime_adoption_track_as_str);
        let limit =
            i64::try_from(limit).map_err(|_| DbError::InvalidSourceType("limit".to_string()))?;
        let mut statement = self.conn.prepare(
            r#"
            SELECT
                id,
                track,
                signal,
                feature,
                query,
                context_hash,
                card_id,
                evaluator_id,
                research_report_id,
                note,
                metadata,
                created_at
            FROM runtime_adoption_events
            WHERE (?1 IS NULL OR track = ?1)
              AND (?2 IS NULL OR feature = ?2)
            ORDER BY created_at DESC, id DESC
            LIMIT ?3
            "#,
        )?;
        let rows = statement
            .query_map(params![track, filter.feature.as_deref(), limit], |row| {
                runtime_adoption_event_from_row(row).map_err(row_decode_error)
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn list_knowledge_drawers_for_card_backfill(
        &self,
        filter: &KnowledgeCardFilter,
    ) -> Result<Vec<Drawer>, DbError> {
        let tier = filter.tier.as_ref().map(knowledge_tier_as_str);
        let status = filter.status.as_ref().map(knowledge_status_as_str);
        let domain = filter.domain.as_ref().map(memory_domain_as_str);
        let anchor_kind = filter.anchor_kind.as_ref().map(anchor_kind_as_str);

        let mut statement = self.conn.prepare(&format!(
            r#"
            SELECT {DRAWER_SELECT_COLUMNS}
            FROM drawers
            WHERE deleted_at IS NULL
              AND memory_kind = 'knowledge'
              AND (?1 IS NULL OR tier = ?1)
              AND (?2 IS NULL OR status = ?2)
              AND (?3 IS NULL OR domain = ?3)
              AND (?4 IS NULL OR field = ?4)
              AND (?5 IS NULL OR anchor_kind = ?5)
              AND (?6 IS NULL OR anchor_id = ?6)
            ORDER BY id
            "#,
        ))?;
        let rows = statement
            .query_map(
                params![
                    tier,
                    status,
                    domain,
                    filter.field.as_deref(),
                    anchor_kind,
                    filter.anchor_id.as_deref(),
                ],
                |row| drawer_from_row(row).map_err(row_decode_error),
            )?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn update_knowledge_card(&self, card: &KnowledgeCard) -> Result<bool, DbError> {
        anchor::validate_anchor_domain(&card.domain, &card.anchor_kind)
            .map_err(|message| DbError::InvalidDrawerMetadata(message.to_string()))?;

        let affected = self.conn.execute(
            r#"
            UPDATE knowledge_cards
            SET statement = ?2,
                content = ?3,
                tier = ?4,
                status = ?5,
                domain = ?6,
                field = ?7,
                anchor_kind = ?8,
                anchor_id = ?9,
                parent_anchor_id = ?10,
                scope_constraints = ?11,
                trigger_hints = ?12,
                updated_at = ?13
            WHERE id = ?1
            "#,
            params![
                card.id.as_str(),
                card.statement.as_str(),
                card.content.as_str(),
                knowledge_tier_as_str(&card.tier),
                knowledge_status_as_str(&card.status),
                memory_domain_as_str(&card.domain),
                card.field.as_str(),
                anchor_kind_as_str(&card.anchor_kind),
                card.anchor_id.as_str(),
                card.parent_anchor_id.as_deref(),
                card.scope_constraints.as_deref(),
                encode_optional_json(card.trigger_hints.as_ref())?,
                card.updated_at.as_str(),
            ],
        )?;
        Ok(affected > 0)
    }

    pub fn insert_knowledge_evidence_link(
        &self,
        link: &KnowledgeEvidenceLink,
    ) -> Result<(), DbError> {
        let evidence = self.get_drawer(&link.evidence_drawer_id)?.ok_or_else(|| {
            DbError::InvalidDrawerMetadata(format!(
                "evidence drawer {} does not exist",
                link.evidence_drawer_id
            ))
        })?;
        if evidence.memory_kind != MemoryKind::Evidence {
            return Err(DbError::InvalidDrawerMetadata(format!(
                "evidence link target {} must be an evidence drawer",
                link.evidence_drawer_id
            )));
        }

        self.conn.execute(
            r#"
            INSERT INTO knowledge_evidence_links (
                id,
                card_id,
                evidence_drawer_id,
                role,
                note,
                created_at
            )
            VALUES (?1, ?2, ?3, ?4, ?5, ?6)
            "#,
            params![
                link.id.as_str(),
                link.card_id.as_str(),
                link.evidence_drawer_id.as_str(),
                knowledge_evidence_role_as_str(&link.role),
                link.note.as_deref(),
                link.created_at.as_str(),
            ],
        )?;
        Ok(())
    }

    pub fn knowledge_evidence_links(
        &self,
        card_id: &str,
    ) -> Result<Vec<KnowledgeEvidenceLink>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT id, card_id, evidence_drawer_id, role, note, created_at
            FROM knowledge_evidence_links
            WHERE card_id = ?1
            ORDER BY created_at, id
            "#,
        )?;
        let rows = statement
            .query_map([card_id], |row| {
                knowledge_evidence_link_from_row(row).map_err(row_decode_error)
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn knowledge_evidence_links_for_drawer(
        &self,
        evidence_drawer_id: &str,
    ) -> Result<Vec<KnowledgeEvidenceLink>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT id, card_id, evidence_drawer_id, role, note, created_at
            FROM knowledge_evidence_links
            WHERE evidence_drawer_id = ?1
            ORDER BY created_at, id
            "#,
        )?;
        let rows = statement
            .query_map([evidence_drawer_id], |row| {
                knowledge_evidence_link_from_row(row).map_err(row_decode_error)
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn append_knowledge_event(&self, event: &KnowledgeCardEvent) -> Result<(), DbError> {
        self.conn.execute(
            r#"
            INSERT INTO knowledge_events (
                id,
                card_id,
                event_type,
                from_status,
                to_status,
                reason,
                actor,
                metadata,
                created_at
            )
            VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9)
            "#,
            params![
                event.id.as_str(),
                event.card_id.as_str(),
                knowledge_event_type_as_str(&event.event_type),
                event.from_status.as_ref().map(knowledge_status_as_str),
                event.to_status.as_ref().map(knowledge_status_as_str),
                event.reason.as_str(),
                event.actor.as_deref(),
                encode_optional_json(event.metadata.as_ref())?,
                event.created_at.as_str(),
            ],
        )?;
        Ok(())
    }

    pub fn knowledge_events(&self, card_id: &str) -> Result<Vec<KnowledgeCardEvent>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT
                id,
                card_id,
                event_type,
                from_status,
                to_status,
                reason,
                actor,
                metadata,
                created_at
            FROM knowledge_events
            WHERE card_id = ?1
            ORDER BY created_at, id
            "#,
        )?;
        let rows = statement
            .query_map([card_id], |row| {
                knowledge_event_from_row(row).map_err(row_decode_error)
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn neighbor_chunks(
        &self,
        source_file: &str,
        wing: &str,
        room: Option<&str>,
        chunk_index: i64,
    ) -> Result<ChunkNeighbors, DbError> {
        let prev_index = chunk_index - 1;
        let next_index = chunk_index + 1;
        let sql = r#"
            SELECT id, content, chunk_index
            FROM drawers
            WHERE deleted_at IS NULL
              AND source_file = ?1
              AND wing = ?2
              AND ((?3 IS NULL AND room IS NULL) OR (?3 IS NOT NULL AND room = ?3))
              AND chunk_index IN (?4, ?5)
            ORDER BY chunk_index, id
            "#;
        let mut statement = self.conn.prepare(sql)?;
        let mut rows = statement.query(params![source_file, wing, room, prev_index, next_index])?;
        let mut neighbors = ChunkNeighbors {
            prev: None,
            next: None,
        };

        while let Some(row) = rows.next()? {
            let row_index = row.get::<_, i64>(2)?;
            let Ok(chunk_index) = u32::try_from(row_index) else {
                continue;
            };
            let chunk = NeighborChunk {
                drawer_id: row.get(0)?,
                content: row.get(1)?,
                chunk_index,
            };
            if row_index == prev_index && neighbors.prev.is_none() {
                neighbors.prev = Some(chunk);
            } else if row_index == next_index && neighbors.next.is_none() {
                neighbors.next = Some(chunk);
            }
        }

        Ok(neighbors)
    }

    pub fn soft_delete_drawer(&self, drawer_id: &str) -> Result<bool, DbError> {
        let timestamp = current_timestamp();
        let affected = self.conn.execute(
            "UPDATE drawers SET deleted_at = ?1 WHERE id = ?2 AND deleted_at IS NULL",
            params![timestamp, drawer_id],
        )?;
        Ok(affected > 0)
    }

    pub fn purge_deleted(&self, before: Option<&str>) -> Result<u64, DbError> {
        // First collect IDs to purge, then delete from both tables
        let ids: Vec<String> = if let Some(before) = before {
            let mut stmt = self.conn.prepare(
                "SELECT id FROM drawers WHERE deleted_at IS NOT NULL AND deleted_at < ?1",
            )?;
            stmt.query_map([before], |row| row.get(0))?
                .collect::<std::result::Result<Vec<_>, _>>()?
        } else {
            let mut stmt = self
                .conn
                .prepare("SELECT id FROM drawers WHERE deleted_at IS NOT NULL")?;
            stmt.query_map([], |row| row.get(0))?
                .collect::<std::result::Result<Vec<_>, _>>()?
        };

        if ids.is_empty() {
            return Ok(0);
        }

        // Check if drawer_vectors table exists (lazy-created)
        let vectors_exist: bool = self.conn.query_row(
            "SELECT EXISTS(SELECT 1 FROM sqlite_master WHERE type='table' AND name='drawer_vectors')",
            [],
            |row| row.get(0),
        )?;

        // Wrap the purge in a single transaction. Clearing the
        // triples.source_drawer FK and deleting the drawer must be atomic:
        // another RESTRICT FK (e.g. knowledge_evidence_links.evidence_drawer_id)
        // can block `DELETE FROM drawers`, and without a transaction the prior
        // `UPDATE triples SET source_drawer = NULL` would have already committed
        // — silently dropping provenance for a drawer that was not purged.
        self.conn.execute_batch("BEGIN IMMEDIATE;")?;
        let result = (|| -> Result<u64, DbError> {
            for id in &ids {
                if vectors_exist {
                    self.conn
                        .execute("DELETE FROM drawer_vectors WHERE id = ?1", [id])?;
                }
                // Clear the triples.source_drawer FK (RESTRICT) before the hard
                // delete so purging a soft-deleted drawer referenced by a KG
                // triple does not fail with a FOREIGN KEY constraint error.
                self.conn.execute(
                    "UPDATE triples SET source_drawer = NULL WHERE source_drawer = ?1",
                    [id],
                )?;
                self.conn
                    .execute("DELETE FROM drawers WHERE id = ?1", [id])?;
            }
            Ok(ids.len() as u64)
        })();

        match result {
            Ok(count) => {
                self.conn.execute_batch("COMMIT;")?;
                Ok(count)
            }
            Err(error) => {
                let _ = self.conn.execute_batch("ROLLBACK;");
                Err(error)
            }
        }
    }

    pub fn deleted_drawer_count(&self) -> Result<i64, DbError> {
        Ok(self.conn.query_row(
            "SELECT COUNT(*) FROM drawers WHERE deleted_at IS NOT NULL",
            [],
            |row| row.get(0),
        )?)
    }

    // --- FTS5 BM25 search ---

    pub fn search_fts(
        &self,
        query: &str,
        wing: Option<&str>,
        room: Option<&str>,
        limit: usize,
    ) -> Result<Vec<(String, f64)>, DbError> {
        let Some(match_query) = build_fts_match_query(query) else {
            return Ok(Vec::new());
        };
        let limit =
            i64::try_from(limit).map_err(|_| DbError::InvalidSourceType("limit".to_string()))?;
        let mut stmt = self.conn.prepare(
            r#"
            SELECT d.id, fts.rank
            FROM drawers_fts fts
            JOIN drawers d ON d.rowid = fts.rowid
            WHERE drawers_fts MATCH ?1
              AND d.deleted_at IS NULL
              AND (?2 IS NULL OR d.wing = ?2)
              AND (?3 IS NULL OR d.room = ?3)
            ORDER BY fts.rank
            LIMIT ?4
            "#,
        )?;
        let rows = stmt
            .query_map((match_query.as_str(), wing, room, limit), |row| {
                Ok((row.get::<_, String>(0)?, row.get::<_, f64>(1)?))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    // --- Triples (Knowledge Graph) ---

    pub fn insert_triple(&self, triple: &Triple) -> Result<(), DbError> {
        self.conn.execute(
            r#"
            INSERT OR REPLACE INTO triples (id, subject, predicate, object, valid_from, valid_to, confidence, source_drawer)
            VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)
            "#,
            params![
                triple.id,
                triple.subject,
                triple.predicate,
                triple.object,
                triple.valid_from,
                triple.valid_to,
                triple.confidence,
                triple.source_drawer,
            ],
        )?;
        Ok(())
    }

    pub fn query_triples(
        &self,
        subject: Option<&str>,
        predicate: Option<&str>,
        object: Option<&str>,
        active_only: bool,
    ) -> Result<Vec<Triple>, DbError> {
        let active_clause = if active_only {
            "AND (valid_to IS NULL OR valid_to > strftime('%s', 'now'))"
        } else {
            ""
        };
        let sql = format!(
            r#"
            SELECT id, subject, predicate, object, valid_from, valid_to, confidence, source_drawer
            FROM triples
            WHERE (?1 IS NULL OR subject = ?1)
              AND (?2 IS NULL OR predicate = ?2)
              AND (?3 IS NULL OR object = ?3)
              {active_clause}
            ORDER BY confidence DESC, id
            "#
        );
        let mut stmt = self.conn.prepare(&sql)?;
        let rows = stmt
            .query_map((subject, predicate, object), |row| {
                Ok(Triple {
                    id: row.get(0)?,
                    subject: row.get(1)?,
                    predicate: row.get(2)?,
                    object: row.get(3)?,
                    valid_from: row.get(4)?,
                    valid_to: row.get(5)?,
                    confidence: row.get(6)?,
                    source_drawer: row.get(7)?,
                })
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn invalidate_triple(&self, triple_id: &str) -> Result<bool, DbError> {
        let timestamp = current_timestamp();
        let affected = self.conn.execute(
            "UPDATE triples SET valid_to = ?1 WHERE id = ?2 AND valid_to IS NULL",
            params![timestamp, triple_id],
        )?;
        Ok(affected > 0)
    }

    pub fn triple_count(&self) -> Result<i64, DbError> {
        Ok(self
            .conn
            .query_row("SELECT COUNT(*) FROM triples", [], |row| row.get(0))?)
    }

    pub fn timeline_for_entity(&self, entity: &str) -> Result<Vec<Triple>, DbError> {
        let mut stmt = self.conn.prepare(
            r#"
            SELECT id, subject, predicate, object, valid_from, valid_to, confidence, source_drawer
            FROM triples
            WHERE subject = ?1 OR object = ?1
            ORDER BY COALESCE(valid_from, '0') ASC, id ASC
            "#,
        )?;
        let rows = stmt
            .query_map([entity], |row| {
                Ok(Triple {
                    id: row.get(0)?,
                    subject: row.get(1)?,
                    predicate: row.get(2)?,
                    object: row.get(3)?,
                    valid_from: row.get(4)?,
                    valid_to: row.get(5)?,
                    confidence: row.get(6)?,
                    source_drawer: row.get(7)?,
                })
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn triple_stats(&self) -> Result<TripleStats, DbError> {
        let total: i64 = self
            .conn
            .query_row("SELECT COUNT(*) FROM triples", [], |row| row.get(0))?;
        let active: i64 = self.conn.query_row(
            "SELECT COUNT(*) FROM triples WHERE valid_to IS NULL",
            [],
            |row| row.get(0),
        )?;
        let expired = total - active;
        let entities: i64 = self.conn.query_row(
            r#"
            SELECT COUNT(DISTINCT entity) FROM (
                SELECT subject AS entity FROM triples
                UNION
                SELECT object AS entity FROM triples
            )
            "#,
            [],
            |row| row.get(0),
        )?;
        let mut top_predicates_stmt = self.conn.prepare(
            "SELECT predicate, COUNT(*) as cnt FROM triples GROUP BY predicate ORDER BY cnt DESC LIMIT 5",
        )?;
        let top_predicates = top_predicates_stmt
            .query_map([], |row| {
                Ok((row.get::<_, String>(0)?, row.get::<_, i64>(1)?))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(TripleStats {
            total,
            active,
            expired,
            entities,
            top_predicates,
        })
    }

    // --- Tunnels (cross-Wing discovery) ---

    pub fn find_tunnels(&self) -> Result<Vec<(String, Vec<String>)>, DbError> {
        let mut stmt = self.conn.prepare(
            r#"
            SELECT room, GROUP_CONCAT(DISTINCT wing) as wings
            FROM drawers
            WHERE deleted_at IS NULL AND room IS NOT NULL AND room != ''
            GROUP BY room
            HAVING COUNT(DISTINCT wing) > 1
            ORDER BY room
            "#,
        )?;
        let rows = stmt
            .query_map([], |row| {
                let room: String = row.get(0)?;
                let wings_csv: String = row.get(1)?;
                Ok((room, wings_csv))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows
            .into_iter()
            .map(|(room, wings_csv)| {
                let wings = wings_csv.split(',').map(ToOwned::to_owned).collect();
                (room, wings)
            })
            .collect())
    }

    pub fn create_tunnel(
        &self,
        left: &TunnelEndpoint,
        right: &TunnelEndpoint,
        label: &str,
        created_by: Option<&str>,
    ) -> Result<ExplicitTunnel, DbError> {
        let left = normalize_tunnel_endpoint(left)?;
        let right = normalize_tunnel_endpoint(right)?;
        let label = label.trim();
        if label.is_empty() {
            return Err(DbError::InvalidTunnel("label is required".to_string()));
        }
        if left == right {
            return Err(DbError::InvalidTunnel(
                "self-link is not allowed".to_string(),
            ));
        }

        let id = build_tunnel_id(&left, &right);
        let created_at = current_timestamp();
        let created_by = created_by
            .map(str::trim)
            .filter(|value| !value.is_empty())
            .map(ToOwned::to_owned);
        self.conn.execute(
            r#"
            INSERT INTO tunnels (
                id, left_wing, left_room, right_wing, right_room,
                label, created_at, created_by, deleted_at
            )
            VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, NULL)
            ON CONFLICT(id) DO UPDATE SET
                label = CASE
                    WHEN tunnels.deleted_at IS NOT NULL THEN excluded.label
                    ELSE tunnels.label
                END,
                created_at = CASE
                    WHEN tunnels.deleted_at IS NOT NULL THEN excluded.created_at
                    ELSE tunnels.created_at
                END,
                created_by = CASE
                    WHEN tunnels.deleted_at IS NOT NULL THEN excluded.created_by
                    ELSE tunnels.created_by
                END,
                deleted_at = NULL
            "#,
            params![
                id, left.wing, left.room, right.wing, right.room, label, created_at, created_by,
            ],
        )?;

        self.get_explicit_tunnel(&id)?
            .ok_or_else(|| DbError::InvalidTunnel(format!("failed to create tunnel {id}")))
    }

    pub fn list_explicit_tunnels(
        &self,
        wing: Option<&str>,
    ) -> Result<Vec<ExplicitTunnel>, DbError> {
        let wing = wing.map(str::trim).filter(|value| !value.is_empty());
        let mut statement = self.conn.prepare(
            r#"
            SELECT id, left_wing, left_room, right_wing, right_room,
                   label, created_at, created_by, deleted_at
            FROM tunnels
            WHERE deleted_at IS NULL
              AND (?1 IS NULL OR left_wing = ?1 OR right_wing = ?1)
            ORDER BY left_wing, left_room, right_wing, right_room, id
            "#,
        )?;
        let rows = statement
            .query_map([wing], explicit_tunnel_from_row)?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn delete_explicit_tunnel(&self, tunnel_id: &str) -> Result<bool, DbError> {
        let timestamp = current_timestamp();
        let affected = self.conn.execute(
            "UPDATE tunnels SET deleted_at = ?1 WHERE id = ?2 AND deleted_at IS NULL",
            params![timestamp, tunnel_id],
        )?;
        Ok(affected > 0)
    }

    pub fn follow_explicit_tunnels(
        &self,
        from: &TunnelEndpoint,
        max_hops: u8,
    ) -> Result<Vec<TunnelFollowResult>, DbError> {
        if !(1..=2).contains(&max_hops) {
            return Err(DbError::InvalidTunnel(
                "max_hops must be 1 or 2".to_string(),
            ));
        }

        let from = normalize_tunnel_endpoint(from)?;
        let tunnels = self.list_explicit_tunnels(None)?;
        let mut visited = BTreeSet::from([from.clone()]);
        let mut queue = VecDeque::from([(from, 0_u8)]);
        let mut results = Vec::new();

        while let Some((current, hop)) = queue.pop_front() {
            if hop >= max_hops {
                continue;
            }
            let next_hop = hop + 1;
            for tunnel in &tunnels {
                let neighbor = if tunnel.left == current {
                    Some(tunnel.right.clone())
                } else if tunnel.right == current {
                    Some(tunnel.left.clone())
                } else {
                    None
                };
                let Some(neighbor) = neighbor else {
                    continue;
                };
                if !visited.insert(neighbor.clone()) {
                    continue;
                }
                results.push(TunnelFollowResult {
                    endpoint: neighbor.clone(),
                    via_tunnel_id: tunnel.id.clone(),
                    hop: next_hop,
                });
                queue.push_back((neighbor, next_hop));
            }
        }

        results.sort_by(|left, right| {
            left.hop
                .cmp(&right.hop)
                .then_with(|| left.endpoint.cmp(&right.endpoint))
                .then_with(|| left.via_tunnel_id.cmp(&right.via_tunnel_id))
        });
        Ok(results)
    }

    pub fn explicit_tunnel_hints(
        &self,
        wing: &str,
        room: Option<&str>,
    ) -> Result<Vec<String>, DbError> {
        let endpoint = TunnelEndpoint {
            wing: wing.to_string(),
            room: room.map(ToOwned::to_owned),
        };
        let hints = self
            .follow_explicit_tunnels(&endpoint, 1)?
            .into_iter()
            .map(|result| format_tunnel_endpoint(&result.endpoint))
            .collect::<BTreeSet<_>>()
            .into_iter()
            .collect();
        Ok(hints)
    }

    fn get_explicit_tunnel(&self, tunnel_id: &str) -> Result<Option<ExplicitTunnel>, DbError> {
        let mut statement = self.conn.prepare(
            r#"
            SELECT id, left_wing, left_room, right_wing, right_room,
                   label, created_at, created_by, deleted_at
            FROM tunnels
            WHERE id = ?1 AND deleted_at IS NULL
            "#,
        )?;
        let mut rows = statement.query_map([tunnel_id], explicit_tunnel_from_row)?;
        match rows.next() {
            Some(row) => Ok(Some(row?)),
            None => Ok(None),
        }
    }

    // --- Embedding dimension management ---

    /// Returns the current embedding dimension from the vec0 table, or None if the table is empty.
    pub fn embedding_dim(&self) -> Result<Option<usize>, DbError> {
        // sqlite-vec stores dimension in table schema; probe by checking a row
        let result: std::result::Result<i64, _> = self.conn.query_row(
            "SELECT vec_length(embedding) FROM drawer_vectors LIMIT 1",
            [],
            |row| row.get(0),
        );
        match result {
            Ok(dim) => Ok(Some(dim as usize)),
            Err(rusqlite::Error::QueryReturnedNoRows) => Ok(None),
            Err(e) => Err(DbError::Sqlite(e)),
        }
    }

    /// Drop and recreate the drawer_vectors table with the specified dimension.
    /// All existing vectors are lost — caller must re-embed after this.
    pub fn recreate_vectors_table(&self, dim: usize) -> Result<(), DbError> {
        self.conn.execute_batch(&format!(
            r#"
            DROP TABLE IF EXISTS drawer_vectors;
            CREATE VIRTUAL TABLE drawer_vectors USING vec0(
                id TEXT PRIMARY KEY,
                embedding FLOAT[{dim}]
            );
            "#
        ))?;
        Ok(())
    }

    /// Returns all active (non-deleted) drawer IDs and their content for re-embedding.
    pub fn all_active_drawers(&self) -> Result<Vec<(String, String)>, DbError> {
        let mut stmt = self
            .conn
            .prepare("SELECT id, content FROM drawers WHERE deleted_at IS NULL ORDER BY id")?;
        let rows = stmt
            .query_map([], |row| {
                Ok((row.get::<_, String>(0)?, row.get::<_, String>(1)?))
            })?
            .collect::<std::result::Result<Vec<_>, _>>()?;
        Ok(rows)
    }

    pub fn database_size_bytes(&self) -> Result<u64, DbError> {
        fs::metadata(&self.path)
            .map(|metadata| metadata.len())
            .map_err(|source| DbError::Metadata {
                path: self.path.clone(),
                source,
            })
    }

    pub fn schema_version(&self) -> Result<u32, DbError> {
        read_user_version(&self.conn)
    }
}

fn apply_migrations(conn: &Connection) -> Result<(), DbError> {
    let current_version = read_user_version(conn)?;
    if current_version > CURRENT_SCHEMA_VERSION {
        return Err(DbError::UnsupportedSchemaVersion {
            current: current_version,
            supported: CURRENT_SCHEMA_VERSION,
        });
    }

    for migration in migrations()
        .iter()
        .filter(|migration| migration.version > current_version)
    {
        apply_migration_atomic(conn, migration)?;
    }

    Ok(())
}

fn apply_migration_atomic(conn: &Connection, migration: &Migration) -> Result<(), DbError> {
    conn.execute_batch("BEGIN IMMEDIATE;")?;
    if let Err(error) = (|| -> Result<(), DbError> {
        conn.execute_batch(migration.sql)?;
        set_user_version(conn, migration.version)?;
        conn.execute_batch("COMMIT;")?;
        Ok(())
    })() {
        let _ = conn.execute_batch("ROLLBACK;");
        return Err(error);
    }
    Ok(())
}

fn read_user_version(conn: &Connection) -> Result<u32, DbError> {
    let version = conn.query_row("PRAGMA user_version", [], |row| row.get::<_, u32>(0))?;
    Ok(version)
}

fn set_user_version(conn: &Connection, version: u32) -> Result<(), DbError> {
    conn.execute_batch(&format!("PRAGMA user_version = {version};"))?;
    Ok(())
}

fn normalize_tunnel_endpoint(endpoint: &TunnelEndpoint) -> Result<TunnelEndpoint, DbError> {
    let wing = endpoint.wing.trim();
    if wing.is_empty() {
        return Err(DbError::InvalidTunnel(
            "endpoint wing is required".to_string(),
        ));
    }
    let room = endpoint
        .room
        .as_deref()
        .map(str::trim)
        .filter(|room| !room.is_empty())
        .map(ToOwned::to_owned);
    Ok(TunnelEndpoint {
        wing: wing.to_string(),
        room,
    })
}

fn explicit_tunnel_from_row(row: &Row<'_>) -> rusqlite::Result<ExplicitTunnel> {
    Ok(ExplicitTunnel {
        id: row.get(0)?,
        left: TunnelEndpoint {
            wing: row.get(1)?,
            room: row.get(2)?,
        },
        right: TunnelEndpoint {
            wing: row.get(3)?,
            room: row.get(4)?,
        },
        label: row.get(5)?,
        created_at: row.get(6)?,
        created_by: row.get(7)?,
        deleted_at: row.get(8)?,
    })
}

fn reindex_source_from_row(row: &Row<'_>) -> rusqlite::Result<ReindexSource> {
    let drawer_count = row.get::<_, i64>(3)?;
    Ok(ReindexSource {
        source_file: row.get(0)?,
        wing: row.get(1)?,
        room: row.get(2)?,
        drawer_count: drawer_count as u64,
    })
}

const V2_MIGRATION_SQL: &str = r#"
ALTER TABLE drawers ADD COLUMN deleted_at TEXT;
CREATE INDEX IF NOT EXISTS idx_drawers_deleted_at ON drawers(deleted_at);
"#;

const V3_MIGRATION_SQL: &str = r#"
CREATE VIRTUAL TABLE IF NOT EXISTS drawers_fts USING fts5(
    content,
    content='drawers',
    content_rowid='rowid'
);

-- Populate FTS from existing drawers (excluding soft-deleted)
INSERT INTO drawers_fts(rowid, content)
    SELECT rowid, content FROM drawers WHERE deleted_at IS NULL;

-- Keep FTS in sync: INSERT trigger
CREATE TRIGGER IF NOT EXISTS drawers_ai AFTER INSERT ON drawers BEGIN
    INSERT INTO drawers_fts(rowid, content) VALUES (new.rowid, new.content);
END;

-- Keep FTS in sync: soft-delete (UPDATE deleted_at) removes from FTS
CREATE TRIGGER IF NOT EXISTS drawers_au_softdelete AFTER UPDATE OF deleted_at ON drawers
    WHEN new.deleted_at IS NOT NULL AND old.deleted_at IS NULL BEGIN
    INSERT INTO drawers_fts(drawers_fts, rowid, content) VALUES ('delete', old.rowid, old.content);
END;

-- No DELETE trigger on drawers — soft-deleted rows are already removed from FTS
-- by the UPDATE trigger above. Physical DELETE (purge) skips FTS because the
-- entry is already gone.
"#;

const V4_MIGRATION_SQL: &str = r#"
ALTER TABLE drawers ADD COLUMN importance INTEGER DEFAULT 0;
"#;

const V5_MIGRATION_SQL: &str = r#"
ALTER TABLE drawers ADD COLUMN memory_kind TEXT NOT NULL CHECK(memory_kind IN ('evidence', 'knowledge')) DEFAULT 'evidence';
ALTER TABLE drawers ADD COLUMN domain TEXT NOT NULL CHECK(domain IN ('project', 'agent', 'skill', 'global')) DEFAULT 'project';
ALTER TABLE drawers ADD COLUMN field TEXT NOT NULL DEFAULT 'general';
ALTER TABLE drawers ADD COLUMN anchor_kind TEXT NOT NULL CHECK(anchor_kind IN ('global', 'repo', 'worktree')) DEFAULT 'repo';
ALTER TABLE drawers ADD COLUMN anchor_id TEXT NOT NULL DEFAULT 'repo://legacy';
ALTER TABLE drawers ADD COLUMN parent_anchor_id TEXT;
ALTER TABLE drawers ADD COLUMN provenance TEXT CHECK(provenance IN ('runtime', 'research', 'human'));
ALTER TABLE drawers ADD COLUMN statement TEXT;
ALTER TABLE drawers ADD COLUMN tier TEXT CHECK(tier IN ('qi', 'shu', 'dao_ren', 'dao_tian'));
ALTER TABLE drawers ADD COLUMN status TEXT CHECK(status IN ('candidate', 'promoted', 'canonical', 'demoted', 'retired'));
ALTER TABLE drawers ADD COLUMN supporting_refs TEXT NOT NULL DEFAULT '[]';
ALTER TABLE drawers ADD COLUMN counterexample_refs TEXT NOT NULL DEFAULT '[]';
ALTER TABLE drawers ADD COLUMN teaching_refs TEXT NOT NULL DEFAULT '[]';
ALTER TABLE drawers ADD COLUMN verification_refs TEXT NOT NULL DEFAULT '[]';
ALTER TABLE drawers ADD COLUMN scope_constraints TEXT;
ALTER TABLE drawers ADD COLUMN trigger_hints TEXT;

UPDATE drawers
SET memory_kind = 'evidence',
    domain = 'project',
    field = 'general',
    anchor_kind = 'repo',
    anchor_id = 'repo://legacy',
    parent_anchor_id = NULL,
    provenance = CASE source_type
        WHEN 'project' THEN 'research'
        WHEN 'conversation' THEN 'human'
        WHEN 'manual' THEN 'human'
        ELSE NULL
    END
WHERE memory_kind = 'evidence'
  AND domain = 'project'
  AND field = 'general'
  AND anchor_kind = 'repo'
  AND anchor_id = 'repo://legacy'
  AND parent_anchor_id IS NULL
  AND provenance IS NULL;
"#;

const V6_MIGRATION_SQL: &str = r#"
CREATE TABLE IF NOT EXISTS tunnels (
    id TEXT PRIMARY KEY,
    left_wing TEXT NOT NULL,
    left_room TEXT,
    right_wing TEXT NOT NULL,
    right_room TEXT,
    label TEXT NOT NULL,
    created_at TEXT NOT NULL,
    created_by TEXT,
    deleted_at TEXT
);

CREATE INDEX IF NOT EXISTS idx_tunnels_left
    ON tunnels(left_wing, left_room)
    WHERE deleted_at IS NULL;

CREATE INDEX IF NOT EXISTS idx_tunnels_right
    ON tunnels(right_wing, right_room)
    WHERE deleted_at IS NULL;
"#;

const V7_MIGRATION_SQL: &str = r#"
ALTER TABLE drawers ADD COLUMN normalize_version INTEGER NOT NULL DEFAULT 1;

CREATE INDEX IF NOT EXISTS idx_drawers_normalize_version
    ON drawers(normalize_version)
    WHERE deleted_at IS NULL;
"#;

const V8_MIGRATION_SQL: &str = r#"
CREATE TABLE IF NOT EXISTS knowledge_cards (
    id TEXT PRIMARY KEY,
    statement TEXT NOT NULL,
    content TEXT NOT NULL,
    tier TEXT NOT NULL CHECK(tier IN ('qi', 'shu', 'dao_ren', 'dao_tian')),
    status TEXT NOT NULL CHECK(status IN ('candidate', 'promoted', 'canonical', 'demoted', 'retired')),
    domain TEXT NOT NULL CHECK(domain IN ('project', 'agent', 'skill', 'global')),
    field TEXT NOT NULL DEFAULT 'general',
    anchor_kind TEXT NOT NULL CHECK(anchor_kind IN ('global', 'repo', 'worktree')),
    anchor_id TEXT NOT NULL,
    parent_anchor_id TEXT,
    scope_constraints TEXT,
    trigger_hints TEXT,
    created_at TEXT NOT NULL,
    updated_at TEXT NOT NULL
);

CREATE TABLE IF NOT EXISTS knowledge_evidence_links (
    id TEXT PRIMARY KEY,
    card_id TEXT NOT NULL,
    evidence_drawer_id TEXT NOT NULL,
    role TEXT NOT NULL CHECK(role IN ('supporting', 'verification', 'counterexample', 'teaching')),
    note TEXT,
    created_at TEXT NOT NULL,
    UNIQUE(card_id, evidence_drawer_id, role),
    FOREIGN KEY(card_id) REFERENCES knowledge_cards(id) ON DELETE RESTRICT,
    FOREIGN KEY(evidence_drawer_id) REFERENCES drawers(id) ON DELETE RESTRICT
);

CREATE TABLE IF NOT EXISTS knowledge_events (
    id TEXT PRIMARY KEY,
    card_id TEXT NOT NULL,
    event_type TEXT NOT NULL CHECK(event_type IN ('created', 'promoted', 'demoted', 'retired', 'linked', 'unlinked', 'updated', 'published_anchor')),
    from_status TEXT,
    to_status TEXT,
    reason TEXT NOT NULL,
    actor TEXT,
    metadata TEXT,
    created_at TEXT NOT NULL,
    FOREIGN KEY(card_id) REFERENCES knowledge_cards(id) ON DELETE RESTRICT
);

CREATE INDEX IF NOT EXISTS idx_knowledge_cards_tier_status
    ON knowledge_cards(tier, status);

CREATE INDEX IF NOT EXISTS idx_knowledge_cards_domain_field
    ON knowledge_cards(domain, field);

CREATE INDEX IF NOT EXISTS idx_knowledge_cards_anchor
    ON knowledge_cards(anchor_kind, anchor_id);

CREATE INDEX IF NOT EXISTS idx_knowledge_evidence_links_card
    ON knowledge_evidence_links(card_id);

CREATE INDEX IF NOT EXISTS idx_knowledge_evidence_links_evidence
    ON knowledge_evidence_links(evidence_drawer_id);

CREATE INDEX IF NOT EXISTS idx_knowledge_events_card_created_at
    ON knowledge_events(card_id, created_at);

CREATE TRIGGER IF NOT EXISTS knowledge_events_no_update
BEFORE UPDATE ON knowledge_events
BEGIN
    SELECT RAISE(ABORT, 'knowledge_events are append-only');
END;

CREATE TRIGGER IF NOT EXISTS knowledge_events_no_delete
BEFORE DELETE ON knowledge_events
BEGIN
    SELECT RAISE(ABORT, 'knowledge_events are append-only');
END;
"#;

const V9_MIGRATION_SQL: &str = r#"
CREATE TABLE IF NOT EXISTS runtime_adoption_events (
    id TEXT PRIMARY KEY,
    track TEXT NOT NULL CHECK(track IN ('runtime_adoption', 'card_context', 'card_embedding', 'evaluator', 'research_adapter')),
    signal TEXT NOT NULL CHECK(signal IN ('used', 'accepted', 'rejected', 'miss', 'rollback', 'contradiction', 'neutral')),
    feature TEXT NOT NULL,
    query TEXT,
    context_hash TEXT,
    card_id TEXT,
    evaluator_id TEXT,
    research_report_id TEXT,
    note TEXT,
    metadata TEXT,
    created_at TEXT NOT NULL,
    FOREIGN KEY(card_id) REFERENCES knowledge_cards(id) ON DELETE SET NULL
);

CREATE INDEX IF NOT EXISTS idx_runtime_adoption_events_track_created_at
    ON runtime_adoption_events(track, created_at);

CREATE INDEX IF NOT EXISTS idx_runtime_adoption_events_feature
    ON runtime_adoption_events(feature);

CREATE INDEX IF NOT EXISTS idx_runtime_adoption_events_signal
    ON runtime_adoption_events(signal);
"#;

fn migrations() -> &'static [Migration] {
    static MIGRATIONS: &[Migration] = &[
        Migration {
            version: 1,
            sql: V1_SCHEMA_SQL,
        },
        Migration {
            version: 2,
            sql: V2_MIGRATION_SQL,
        },
        Migration {
            version: 3,
            sql: V3_MIGRATION_SQL,
        },
        Migration {
            version: 4,
            sql: V4_MIGRATION_SQL,
        },
        Migration {
            version: 5,
            sql: V5_MIGRATION_SQL,
        },
        Migration {
            version: 6,
            sql: V6_MIGRATION_SQL,
        },
        Migration {
            version: 7,
            sql: V7_MIGRATION_SQL,
        },
        Migration {
            version: 8,
            sql: V8_MIGRATION_SQL,
        },
        Migration {
            version: 9,
            sql: V9_MIGRATION_SQL,
        },
    ];
    MIGRATIONS
}

struct Migration {
    version: u32,
    sql: &'static str,
}

fn register_sqlite_vec() -> Result<(), DbError> {
    SQLITE_VEC_AUTO_EXTENSION
        .get_or_init(|| unsafe {
            // sqlite-vec exposes a standard SQLite extension init symbol; auto-registration
            // makes vec0 available on every subsequently opened connection in this process.
            let init: rusqlite::auto_extension::RawAutoExtension =
                std::mem::transmute::<*const (), rusqlite::auto_extension::RawAutoExtension>(
                    sqlite_vec::sqlite3_vec_init as *const (),
                );

            rusqlite::auto_extension::register_auto_extension(init)
                .map_err(|error| error.to_string())
        })
        .as_ref()
        .map(|_| ())
        .map_err(|message| DbError::RegisterVec(message.clone()))
}

fn source_type_as_str(source_type: &SourceType) -> &'static str {
    match source_type {
        SourceType::Project => "project",
        SourceType::Conversation => "conversation",
        SourceType::Manual => "manual",
    }
}

fn source_type_from_str(source_type: &str) -> Result<SourceType, DbError> {
    match source_type {
        "project" => Ok(SourceType::Project),
        "conversation" => Ok(SourceType::Conversation),
        "manual" => Ok(SourceType::Manual),
        other => Err(DbError::InvalidSourceType(other.to_string())),
    }
}

fn memory_kind_as_str(memory_kind: &MemoryKind) -> &'static str {
    match memory_kind {
        MemoryKind::Evidence => "evidence",
        MemoryKind::Knowledge => "knowledge",
    }
}

fn memory_kind_from_str(memory_kind: &str) -> Result<MemoryKind, DbError> {
    match memory_kind {
        "evidence" => Ok(MemoryKind::Evidence),
        "knowledge" => Ok(MemoryKind::Knowledge),
        other => Err(DbError::InvalidEnumValue {
            kind: "memory_kind",
            value: other.to_string(),
        }),
    }
}

fn memory_domain_as_str(domain: &MemoryDomain) -> &'static str {
    match domain {
        MemoryDomain::Project => "project",
        MemoryDomain::Agent => "agent",
        MemoryDomain::Skill => "skill",
        MemoryDomain::Global => "global",
    }
}

fn memory_domain_from_str(domain: &str) -> Result<MemoryDomain, DbError> {
    match domain {
        "project" => Ok(MemoryDomain::Project),
        "agent" => Ok(MemoryDomain::Agent),
        "skill" => Ok(MemoryDomain::Skill),
        "global" => Ok(MemoryDomain::Global),
        other => Err(DbError::InvalidEnumValue {
            kind: "domain",
            value: other.to_string(),
        }),
    }
}

fn anchor_kind_as_str(anchor_kind: &AnchorKind) -> &'static str {
    match anchor_kind {
        AnchorKind::Global => "global",
        AnchorKind::Repo => "repo",
        AnchorKind::Worktree => "worktree",
    }
}

fn anchor_kind_from_str(anchor_kind: &str) -> Result<AnchorKind, DbError> {
    match anchor_kind {
        "global" => Ok(AnchorKind::Global),
        "repo" => Ok(AnchorKind::Repo),
        "worktree" => Ok(AnchorKind::Worktree),
        other => Err(DbError::InvalidEnumValue {
            kind: "anchor_kind",
            value: other.to_string(),
        }),
    }
}

fn provenance_as_str(provenance: &Provenance) -> &'static str {
    match provenance {
        Provenance::Runtime => "runtime",
        Provenance::Research => "research",
        Provenance::Human => "human",
    }
}

fn provenance_from_str(provenance: &str) -> Result<Provenance, DbError> {
    match provenance {
        "runtime" => Ok(Provenance::Runtime),
        "research" => Ok(Provenance::Research),
        "human" => Ok(Provenance::Human),
        other => Err(DbError::InvalidEnumValue {
            kind: "provenance",
            value: other.to_string(),
        }),
    }
}

fn knowledge_tier_as_str(tier: &KnowledgeTier) -> &'static str {
    match tier {
        KnowledgeTier::Qi => "qi",
        KnowledgeTier::Shu => "shu",
        KnowledgeTier::DaoRen => "dao_ren",
        KnowledgeTier::DaoTian => "dao_tian",
    }
}

fn knowledge_tier_from_str(tier: &str) -> Result<KnowledgeTier, DbError> {
    match tier {
        "qi" => Ok(KnowledgeTier::Qi),
        "shu" => Ok(KnowledgeTier::Shu),
        "dao_ren" => Ok(KnowledgeTier::DaoRen),
        "dao_tian" => Ok(KnowledgeTier::DaoTian),
        other => Err(DbError::InvalidEnumValue {
            kind: "tier",
            value: other.to_string(),
        }),
    }
}

fn knowledge_status_as_str(status: &KnowledgeStatus) -> &'static str {
    match status {
        KnowledgeStatus::Candidate => "candidate",
        KnowledgeStatus::Promoted => "promoted",
        KnowledgeStatus::Canonical => "canonical",
        KnowledgeStatus::Demoted => "demoted",
        KnowledgeStatus::Retired => "retired",
    }
}

fn knowledge_status_from_str(status: &str) -> Result<KnowledgeStatus, DbError> {
    match status {
        "candidate" => Ok(KnowledgeStatus::Candidate),
        "promoted" => Ok(KnowledgeStatus::Promoted),
        "canonical" => Ok(KnowledgeStatus::Canonical),
        "demoted" => Ok(KnowledgeStatus::Demoted),
        "retired" => Ok(KnowledgeStatus::Retired),
        other => Err(DbError::InvalidEnumValue {
            kind: "status",
            value: other.to_string(),
        }),
    }
}

fn knowledge_evidence_role_as_str(role: &KnowledgeEvidenceRole) -> &'static str {
    match role {
        KnowledgeEvidenceRole::Supporting => "supporting",
        KnowledgeEvidenceRole::Verification => "verification",
        KnowledgeEvidenceRole::Counterexample => "counterexample",
        KnowledgeEvidenceRole::Teaching => "teaching",
    }
}

fn knowledge_evidence_role_from_str(role: &str) -> Result<KnowledgeEvidenceRole, DbError> {
    match role {
        "supporting" => Ok(KnowledgeEvidenceRole::Supporting),
        "verification" => Ok(KnowledgeEvidenceRole::Verification),
        "counterexample" => Ok(KnowledgeEvidenceRole::Counterexample),
        "teaching" => Ok(KnowledgeEvidenceRole::Teaching),
        other => Err(DbError::InvalidEnumValue {
            kind: "knowledge_evidence_role",
            value: other.to_string(),
        }),
    }
}

fn knowledge_event_type_as_str(event_type: &KnowledgeEventType) -> &'static str {
    match event_type {
        KnowledgeEventType::Created => "created",
        KnowledgeEventType::Promoted => "promoted",
        KnowledgeEventType::Demoted => "demoted",
        KnowledgeEventType::Retired => "retired",
        KnowledgeEventType::Linked => "linked",
        KnowledgeEventType::Unlinked => "unlinked",
        KnowledgeEventType::Updated => "updated",
        KnowledgeEventType::PublishedAnchor => "published_anchor",
    }
}

fn knowledge_event_type_from_str(event_type: &str) -> Result<KnowledgeEventType, DbError> {
    match event_type {
        "created" => Ok(KnowledgeEventType::Created),
        "promoted" => Ok(KnowledgeEventType::Promoted),
        "demoted" => Ok(KnowledgeEventType::Demoted),
        "retired" => Ok(KnowledgeEventType::Retired),
        "linked" => Ok(KnowledgeEventType::Linked),
        "unlinked" => Ok(KnowledgeEventType::Unlinked),
        "updated" => Ok(KnowledgeEventType::Updated),
        "published_anchor" => Ok(KnowledgeEventType::PublishedAnchor),
        other => Err(DbError::InvalidEnumValue {
            kind: "knowledge_event_type",
            value: other.to_string(),
        }),
    }
}

fn runtime_adoption_track_as_str(track: &RuntimeAdoptionTrack) -> &'static str {
    match track {
        RuntimeAdoptionTrack::RuntimeAdoption => "runtime_adoption",
        RuntimeAdoptionTrack::CardContext => "card_context",
        RuntimeAdoptionTrack::CardEmbedding => "card_embedding",
        RuntimeAdoptionTrack::Evaluator => "evaluator",
        RuntimeAdoptionTrack::ResearchAdapter => "research_adapter",
    }
}

fn runtime_adoption_track_from_str(track: &str) -> Result<RuntimeAdoptionTrack, DbError> {
    match track {
        "runtime_adoption" => Ok(RuntimeAdoptionTrack::RuntimeAdoption),
        "card_context" => Ok(RuntimeAdoptionTrack::CardContext),
        "card_embedding" => Ok(RuntimeAdoptionTrack::CardEmbedding),
        "evaluator" => Ok(RuntimeAdoptionTrack::Evaluator),
        "research_adapter" => Ok(RuntimeAdoptionTrack::ResearchAdapter),
        other => Err(DbError::InvalidEnumValue {
            kind: "runtime_adoption_track",
            value: other.to_string(),
        }),
    }
}

fn runtime_adoption_signal_as_str(signal: &RuntimeAdoptionSignal) -> &'static str {
    match signal {
        RuntimeAdoptionSignal::Used => "used",
        RuntimeAdoptionSignal::Accepted => "accepted",
        RuntimeAdoptionSignal::Rejected => "rejected",
        RuntimeAdoptionSignal::Miss => "miss",
        RuntimeAdoptionSignal::Rollback => "rollback",
        RuntimeAdoptionSignal::Contradiction => "contradiction",
        RuntimeAdoptionSignal::Neutral => "neutral",
    }
}

fn runtime_adoption_signal_from_str(signal: &str) -> Result<RuntimeAdoptionSignal, DbError> {
    match signal {
        "used" => Ok(RuntimeAdoptionSignal::Used),
        "accepted" => Ok(RuntimeAdoptionSignal::Accepted),
        "rejected" => Ok(RuntimeAdoptionSignal::Rejected),
        "miss" => Ok(RuntimeAdoptionSignal::Miss),
        "rollback" => Ok(RuntimeAdoptionSignal::Rollback),
        "contradiction" => Ok(RuntimeAdoptionSignal::Contradiction),
        "neutral" => Ok(RuntimeAdoptionSignal::Neutral),
        other => Err(DbError::InvalidEnumValue {
            kind: "runtime_adoption_signal",
            value: other.to_string(),
        }),
    }
}

fn encode_json<T: serde::Serialize + ?Sized>(value: &T) -> Result<String, DbError> {
    Ok(serde_json::to_string(value)?)
}

fn encode_optional_json<T: serde::Serialize>(value: Option<&T>) -> Result<Option<String>, DbError> {
    value.map(encode_json).transpose()
}

fn parse_string_list(raw: Option<&str>) -> Result<Vec<String>, DbError> {
    let Some(raw) = raw else {
        return Ok(Vec::new());
    };
    Ok(serde_json::from_str::<Vec<String>>(raw)?)
}

fn parse_optional_json<T>(raw: Option<&str>) -> Result<Option<T>, DbError>
where
    T: serde::de::DeserializeOwned,
{
    raw.map(serde_json::from_str)
        .transpose()
        .map_err(DbError::from)
}

fn row_decode_error(error: DbError) -> rusqlite::Error {
    rusqlite::Error::FromSqlConversionFailure(0, rusqlite::types::Type::Text, Box::new(error))
}

fn knowledge_card_from_row(row: &Row<'_>) -> Result<KnowledgeCard, DbError> {
    let tier = knowledge_tier_from_str(&row.get::<_, String>(3)?)?;
    let status = knowledge_status_from_str(&row.get::<_, String>(4)?)?;
    let domain = memory_domain_from_str(&row.get::<_, String>(5)?)?;
    let anchor_kind = anchor_kind_from_str(&row.get::<_, String>(7)?)?;
    let trigger_hints = parse_optional_json(row.get::<_, Option<String>>(11)?.as_deref())?;

    anchor::validate_anchor_domain(&domain, &anchor_kind)
        .map_err(|message| DbError::InvalidDrawerMetadata(message.to_string()))?;

    Ok(KnowledgeCard {
        id: row.get(0)?,
        statement: row.get(1)?,
        content: row.get(2)?,
        tier,
        status,
        domain,
        field: row.get(6)?,
        anchor_kind,
        anchor_id: row.get(8)?,
        parent_anchor_id: row.get(9)?,
        scope_constraints: row.get(10)?,
        trigger_hints,
        created_at: row.get(12)?,
        updated_at: row.get(13)?,
    })
}

fn knowledge_evidence_link_from_row(row: &Row<'_>) -> Result<KnowledgeEvidenceLink, DbError> {
    Ok(KnowledgeEvidenceLink {
        id: row.get(0)?,
        card_id: row.get(1)?,
        evidence_drawer_id: row.get(2)?,
        role: knowledge_evidence_role_from_str(&row.get::<_, String>(3)?)?,
        note: row.get(4)?,
        created_at: row.get(5)?,
    })
}

fn knowledge_event_from_row(row: &Row<'_>) -> Result<KnowledgeCardEvent, DbError> {
    let from_status = row
        .get::<_, Option<String>>(3)?
        .as_deref()
        .map(knowledge_status_from_str)
        .transpose()?;
    let to_status = row
        .get::<_, Option<String>>(4)?
        .as_deref()
        .map(knowledge_status_from_str)
        .transpose()?;
    let metadata = parse_optional_json(row.get::<_, Option<String>>(7)?.as_deref())?;

    Ok(KnowledgeCardEvent {
        id: row.get(0)?,
        card_id: row.get(1)?,
        event_type: knowledge_event_type_from_str(&row.get::<_, String>(2)?)?,
        from_status,
        to_status,
        reason: row.get(5)?,
        actor: row.get(6)?,
        metadata,
        created_at: row.get(8)?,
    })
}

fn runtime_adoption_event_from_row(row: &Row<'_>) -> Result<RuntimeAdoptionEvent, DbError> {
    let metadata = parse_optional_json(row.get::<_, Option<String>>(10)?.as_deref())?;
    Ok(RuntimeAdoptionEvent {
        id: row.get(0)?,
        track: runtime_adoption_track_from_str(&row.get::<_, String>(1)?)?,
        signal: runtime_adoption_signal_from_str(&row.get::<_, String>(2)?)?,
        feature: row.get(3)?,
        query: row.get(4)?,
        context_hash: row.get(5)?,
        card_id: row.get(6)?,
        evaluator_id: row.get(7)?,
        research_report_id: row.get(8)?,
        note: row.get(9)?,
        metadata,
        created_at: row.get(11)?,
    })
}

fn drawer_from_row(row: &Row<'_>) -> Result<Drawer, DbError> {
    let source_type = source_type_from_str(&row.get::<_, String>(5)?)?;
    let memory_kind = memory_kind_from_str(&row.get::<_, String>(10)?)?;
    let domain = memory_domain_from_str(&row.get::<_, String>(11)?)?;
    let field = row.get::<_, String>(12)?;
    let anchor_kind = anchor_kind_from_str(&row.get::<_, String>(13)?)?;
    let anchor_id = row.get::<_, String>(14)?;
    let parent_anchor_id = row.get::<_, Option<String>>(15)?;
    let provenance = row
        .get::<_, Option<String>>(16)?
        .as_deref()
        .map(provenance_from_str)
        .transpose()?;
    let statement = row.get::<_, Option<String>>(17)?;
    let tier = row
        .get::<_, Option<String>>(18)?
        .as_deref()
        .map(knowledge_tier_from_str)
        .transpose()?;
    let status = row
        .get::<_, Option<String>>(19)?
        .as_deref()
        .map(knowledge_status_from_str)
        .transpose()?;
    let supporting_refs = parse_string_list(row.get::<_, Option<String>>(20)?.as_deref())?;
    let counterexample_refs = parse_string_list(row.get::<_, Option<String>>(21)?.as_deref())?;
    let teaching_refs = parse_string_list(row.get::<_, Option<String>>(22)?.as_deref())?;
    let verification_refs = parse_string_list(row.get::<_, Option<String>>(23)?.as_deref())?;
    let scope_constraints = row.get::<_, Option<String>>(24)?;
    let trigger_hints = parse_optional_json(row.get::<_, Option<String>>(25)?.as_deref())?;

    anchor::validate_anchor_domain(&domain, &anchor_kind)
        .map_err(|message| DbError::InvalidDrawerMetadata(message.to_string()))?;

    Ok(Drawer {
        id: row.get(0)?,
        content: row.get(1)?,
        wing: row.get(2)?,
        room: row.get(3)?,
        source_file: row.get(4)?,
        source_type,
        added_at: row.get(6)?,
        chunk_index: row.get(7)?,
        normalize_version: row.get(8)?,
        importance: row.get(9)?,
        memory_kind,
        domain,
        field,
        anchor_kind,
        anchor_id,
        parent_anchor_id,
        provenance,
        statement,
        tier,
        status,
        supporting_refs,
        counterexample_refs,
        teaching_refs,
        verification_refs,
        scope_constraints,
        trigger_hints,
    })
}

fn parse_keywords(raw: Option<&str>) -> Result<Vec<String>, DbError> {
    let Some(raw) = raw else {
        return Ok(Vec::new());
    };

    let value: Value = serde_json::from_str(raw)?;
    let keywords = value
        .as_array()
        .into_iter()
        .flatten()
        .filter_map(|item| item.as_str())
        .map(ToOwned::to_owned)
        .collect();

    Ok(keywords)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_atomic_migration_rolls_back_partial_schema_changes() {
        let conn = Connection::open_in_memory().expect("open in-memory");
        conn.execute_batch(
            r#"
            CREATE TABLE drawers (
                id TEXT PRIMARY KEY,
                content TEXT NOT NULL
            );
            PRAGMA user_version = 4;
            "#,
        )
        .expect("create base schema");

        let migration = Migration {
            version: 5,
            sql: r#"
            ALTER TABLE drawers ADD COLUMN memory_kind TEXT;
            ALTER TABLE missing_table ADD COLUMN nope TEXT;
            "#,
        };

        let error = apply_migration_atomic(&conn, &migration).expect_err("migration should fail");
        assert!(
            matches!(error, DbError::Sqlite(_)),
            "unexpected error: {error:?}"
        );
        assert_eq!(read_user_version(&conn).expect("user_version"), 4);

        let mut stmt = conn
            .prepare("PRAGMA table_info(drawers)")
            .expect("table_info");
        let columns = stmt
            .query_map([], |row| row.get::<_, String>(1))
            .expect("query columns")
            .collect::<std::result::Result<Vec<_>, _>>()
            .expect("collect columns");

        assert!(
            !columns.iter().any(|column| column == "memory_kind"),
            "failed migration must not leave partial columns behind"
        );
    }
}