algocline_app/service/

hub.rs

//! Hub — package discovery, search, and index management.
//!
//! The Hub is algocline's package registry layer.  It aggregates remote
//! index data with local install state so that users (via AI) can
//! **discover** packages they haven't installed yet, and **inspect**
//! installed packages with full Card and eval statistics.
//!
//! ## Staged design
//!
//! | Stage | Scope | Status |
//! |-------|-------|--------|
//! | **1** | Card Collection install, Pkg-bundled cards | Done |
//! | **2** | Hub MCP tools (`hub_search`, `hub_info`, `hub_reindex`), local index | Done |
//! | **3** | Aggregated remote collection index, `hub_publish`, LP | Planned |
//!
//! ## MCP tools
//!
//! | Tool | Description |
//! |------|-------------|
//! | `alc_hub_search` | Discover packages across remote + local indices |
//! | `alc_hub_info` | Detailed single-package view (meta + cards + aliases + stats) |
//! | `alc_hub_reindex` | Rebuild index from local packages or a repo checkout |
//!
//! ## Index schema (`hub_index/v0`)
//!
//! ```json
//! {
//!   "schema_version": "hub_index/v0",
//!   "updated_at": "2026-04-12T10:00:00Z",
//!   "packages": [{
//!     "name": "cot",
//!     "version": "0.1.0",
//!     "description": "Chain-of-Thought prompting",
//!     "category": "reasoning",
//!     "source": "https://github.com/...",
//!     "card_count": 3,
//!     "best_card": { "card_id": "...", "model": "...", "pass_rate": 0.82, "scenario": "..." }
//!   }]
//! }
//! ```
//!
//! Index generation uses `init.lua` M.meta parsing only — no Lua VM
//! required.  This keeps the index buildable in CI environments.
//!
//! ## Index URL discovery (4-tier)
//!
//! Sources are checked in priority order; URLs are deduplicated:
//!
//!   0. **Collection URL** — `[hub].collection_url` in `~/.algocline/config.toml`.
//!      Aggregated index containing all known packages (Stage 3).
//!   1. **Hub registries** — `~/.algocline/hub_registries.json`, auto-populated
//!      by `pkg_install` and `card_install`.
//!   2. **Installed manifest** — `~/.algocline/installed.json`, fallback for
//!      sources registered before registries existed.
//!   3. **Compiled-in seeds** — `AUTO_INSTALL_SOURCES` for first-run bootstrap.
//!
//! GitHub repo URLs are transformed to raw index URLs:
//!
//! ```text
//! https://github.com/{owner}/{repo}
//!   → https://raw.githubusercontent.com/{owner}/{repo}/main/hub_index.json
//! ```
//!
//! ## Caching
//!
//! Remote indices are cached per-source at
//! `~/.algocline/hub_cache/{hash}.json` where hash is FNV-1a of the
//! URL.  TTL is 1 hour.
//!
//! ## Registry persistence
//!
//! `~/.algocline/hub_registries.json` records source URLs from
//! `pkg_install` and `card_install`.  Written atomically (tempfile +
//! rename) to avoid corruption on interruption.

use std::collections::{HashMap, HashSet};
use std::path::PathBuf;

use serde::{Deserialize, Serialize};

use algocline_core::{AppDir, PkgEntity};

use super::list_opts::{
    apply_sort_by_value, matches_filter, parse_sort, project_fields, resolve_fields, ListOpts,
    HUB_SEARCH_FULL, HUB_SEARCH_SUMMARY,
};
use super::manifest;
use super::resolve::AUTO_INSTALL_SOURCES;
use super::source::PackageSource;
use super::AppService;
use super::HubRegistriesError;

// ─── Constants ─────────────────────────────────────────────────

/// Cache TTL in seconds (1 hour).
const CACHE_TTL_SECS: u64 = 3600;

/// HTTP request timeout (30 seconds).
const HTTP_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(30);

// ─── Index schema ──────────────────────────────────────────────

/// Remote index — same shape as the local index so merge is trivial.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub(crate) struct HubIndex {
    pub schema_version: String,
    #[serde(default)]
    pub updated_at: String,
    #[serde(default)]
    pub packages: Vec<IndexEntry>,
}

/// One package in the index.
///
/// `entity` carries the canonical Lua `M.meta` projection (name, version,
/// description, category, docstring) via `#[serde(flatten)]` so the wire
/// shape is identical to the pre-refactor flat-object layout. `source`
/// is the typed package source; `card_count` / `best_card` are hub-side
/// enrichments computed at index-build time.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub(crate) struct IndexEntry {
    #[serde(flatten)]
    pub entity: PkgEntity,
    /// How this package was obtained. Typed on write; legacy bare strings
    /// in pre-migration `hub_index.json` deserialize via the serde shim
    /// on `PackageSource` (see `service::source`).
    #[serde(default)]
    pub source: PackageSource,
    #[serde(default)]
    pub card_count: usize,
    #[serde(default)]
    pub best_card: Option<BestCard>,
}

/// Best card summary within a package.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub(crate) struct BestCard {
    pub card_id: String,
    #[serde(default)]
    pub model: String,
    #[serde(default)]
    pub pass_rate: f64,
    #[serde(default)]
    pub scenario: String,
}

/// Search result — index entry enriched with local install state.
///
/// `entity.docstring` is `skip_serializing` (via the `skip_docstring`
/// custom serializer on the flattened struct) so the default serde output
/// never exposes the docstring field — docstrings can be large and
/// dominate payload size. The `hub_search` projection path re-attaches
/// the docstring to the output object when the resolved field set
/// contains `"docstring"`, via
/// [`SearchResult::to_value_with_optional_docstring`].
///
/// `docstring_matched` is a query-time signal: it is `Some(true)` only
/// when the query hit docstring and none of {name, description, category}.
/// Otherwise (no query, or query hit any of the other fields) it is
/// `None` and omitted from the output.
///
/// Because `#[serde(flatten)]` composes poorly with field-level
/// `skip_serializing`, we carry the non-docstring part of `PkgEntity`
/// via a custom `serialize_entity_without_docstring` path rather than a
/// bare `#[serde(flatten)]`. The struct still holds a full `PkgEntity`
/// internally for consistency with `IndexEntry`.
#[derive(Debug, Clone, Serialize)]
struct SearchResult {
    #[serde(flatten, serialize_with = "serialize_entity_without_docstring")]
    entity: PkgEntity,
    /// Typed source (mirrors `IndexEntry.source`).
    source: PackageSource,
    installed: bool,
    card_count: usize,
    best_card: Option<BestCard>,
    #[serde(skip_serializing_if = "Option::is_none")]
    docstring_matched: Option<bool>,
}

/// Serialize a `PkgEntity` as a flat JSON object, intentionally dropping
/// the `docstring` field so large docstrings do not dominate `hub_search`
/// payloads. The projection path re-attaches docstring via
/// [`SearchResult::to_value_with_optional_docstring`].
fn serialize_entity_without_docstring<S>(entity: &PkgEntity, ser: S) -> Result<S::Ok, S::Error>
where
    S: serde::Serializer,
{
    use serde::ser::SerializeMap;
    let mut map = ser.serialize_map(Some(4))?;
    map.serialize_entry("name", &entity.name)?;
    map.serialize_entry("version", &entity.version)?;
    map.serialize_entry("description", &entity.description)?;
    map.serialize_entry("category", &entity.category)?;
    map.end()
}

impl SearchResult {
    /// Serialize `self` to a JSON `Value`, optionally re-attaching
    /// `docstring` to the resulting object.
    ///
    /// `skip_serializing` removes `docstring` from every serde output
    /// path. When projection selects `docstring` as an output field, we
    /// need to put it back — this helper bridges that gap by inserting
    /// the field manually into the resulting `Value::Object`.
    ///
    /// Returns the original `Value` unchanged if serialization produced
    /// a non-object (should not happen for `SearchResult`, but we stay
    /// defensive because the downstream `project_fields` contract
    /// tolerates non-objects).
    fn to_value_with_optional_docstring(&self, include_docstring: bool) -> serde_json::Value {
        let mut v = serde_json::to_value(self).unwrap_or(serde_json::Value::Null);
        if include_docstring {
            if let serde_json::Value::Object(ref mut map) = v {
                let doc = self.entity.docstring.clone().unwrap_or_default();
                map.insert("docstring".to_string(), serde_json::Value::String(doc));
            }
        }
        v
    }
}

// ─── Hub registries ───────────────────────────────────────────
//
// Persistent file (`~/.algocline/hub_registries.json`) that records
// source URLs from `pkg_install` and `card_install`.  This is the
// primary source for Hub index URL discovery — the manifest and
// `AUTO_INSTALL_SOURCES` serve as fallback seeds.

/// One entry in `hub_registries.json`.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub(crate) struct RegistryEntry {
    /// Original source URL (Git repo or local path).
    pub source: String,
    /// How it was registered: "pkg_install" or "card_install".
    pub origin: String,
    /// ISO 8601 timestamp of when the entry was added.
    pub added_at: String,
}

/// Top-level registries file.
#[derive(Debug, Clone, Serialize, Deserialize, Default)]
pub(crate) struct HubRegistries {
    pub registries: Vec<RegistryEntry>,
}

fn registries_path(app_dir: &AppDir) -> PathBuf {
    app_dir.hub_registries_json()
}

/// Load registries from disk.
///
/// Returns `Ok(HubRegistries::default())` when the file does not yet exist —
/// the file is created lazily on first `register_source` call. Returns `Err`
/// when the file exists but cannot be read (I/O error) or parsed (corrupt
/// JSON), so callers can surface the failure instead of silently degrading hub
/// discovery.
fn load_registries(app_dir: &AppDir) -> Result<HubRegistries, HubRegistriesError> {
    let path = registries_path(app_dir);
    if !path.exists() {
        return Ok(HubRegistries::default());
    }
    let content = std::fs::read_to_string(&path).map_err(|e| {
        HubRegistriesError::Parse(format!(
            "failed to read hub_registries.json at {}: {e}",
            path.display()
        ))
    })?;
    serde_json::from_str::<HubRegistries>(&content).map_err(|e| {
        HubRegistriesError::Parse(format!(
            "failed to parse hub_registries.json at {}: {e}",
            path.display()
        ))
    })
}

/// Register a source URL.  Deduplicates by normalized URL.
///
/// Returns `Ok(())` on success or when the input is skipped (empty /
/// local path / already registered). Filesystem failures are returned
/// as `Err(String)` so callers can surface them on the MCP wire
/// response — the registry is best-effort relative to the `pkg_install`
/// itself, but the caller still needs to know when it silently failed
/// (otherwise hub discovery degrades without any signal).
///
/// Uses atomic write (tempfile + rename) to avoid partial writes if
/// the process is interrupted. Read-modify-write is not locked across
/// processes, but MCP servers are single-process so this is safe in
/// practice.
pub(crate) fn register_source(app_dir: &AppDir, source: &str, origin: &str) -> Result<(), String> {
    let normalized = source.trim_end_matches('/').to_string();
    if normalized.is_empty() {
        return Ok(());
    }
    // Skip local paths — they can't host a remote index
    if normalized.starts_with('/') || normalized.starts_with('.') {
        return Ok(());
    }

    let path = registries_path(app_dir);
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent).map_err(|e| {
            format!(
                "failed to create hub registries dir {}: {e}",
                parent.display()
            )
        })?;
    }

    // Re-read from disk right before write to minimize TOCTOU window.
    // Parse failure is propagated — a corrupt registries file means we
    // cannot safely read-modify-write without risking data loss.
    let mut reg = load_registries(app_dir).map_err(|e| format!("cannot register source: {e}"))?;

    // Already registered?
    if reg
        .registries
        .iter()
        .any(|e| e.source.trim_end_matches('/') == normalized)
    {
        return Ok(());
    }

    reg.registries.push(RegistryEntry {
        source: normalized,
        origin: origin.to_string(),
        added_at: manifest::now_iso8601(),
    });

    // Atomic write: write to temp file, then rename
    let json = serde_json::to_string_pretty(&reg)
        .map_err(|e| format!("failed to serialize hub registries: {e}"))?;
    let tmp_path = path.with_extension("json.tmp");
    std::fs::write(&tmp_path, &json).map_err(|e| {
        format!(
            "failed to write hub registries tmp {}: {e}",
            tmp_path.display()
        )
    })?;
    std::fs::rename(&tmp_path, &path).map_err(|e| {
        // Best-effort cleanup of the stale tmp file on rename failure.
        let _ = std::fs::remove_file(&tmp_path);
        format!(
            "failed to atomically rename hub registries onto {}: {e}",
            path.display()
        )
    })
}

// ─── Hub config ──────────────────────────────────────────────
//
// Optional `[hub]` section in `~/.algocline/config.toml`:
//
//   [hub]
//   collection_url = "https://raw.githubusercontent.com/.../hub_index.json"
//
// When set, this is fetched as Tier 0 (the aggregated collection
// index containing all known packages, including uninstalled ones).

/// Read the `[hub].collection_url` from `~/.algocline/config.toml`.
///
/// Returns:
/// - `Ok(Some(url))` — file exists, parses cleanly, `[hub].collection_url` present and non-empty.
/// - `Ok(None)` — file absent (normal: config is optional) or `[hub].collection_url` not set.
/// - `Err(msg)` — file exists but TOML parse fails (corruption); caller should surface as warning.
fn collection_url_from_config(app_dir: &AppDir) -> Result<Option<String>, String> {
    let path = app_dir.config_toml();
    let content = match std::fs::read_to_string(&path) {
        Ok(c) => c,
        Err(e) if e.kind() == std::io::ErrorKind::NotFound => return Ok(None),
        Err(_) => return Ok(None), // permission errors etc. treated as absent
    };
    let doc: toml_edit::DocumentMut = content
        .parse()
        .map_err(|e| format!("config.toml parse: {e}"))?;
    let url = match doc
        .get("hub")
        .and_then(|h| h.get("collection_url"))
        .and_then(|v| v.as_str())
    {
        Some(s) => s.trim().to_string(),
        None => return Ok(None),
    };
    if url.is_empty() {
        Ok(None)
    } else {
        Ok(Some(url))
    }
}

// ─── Index URL discovery ──────────────────────────────────────
//
// Derives remote index URLs from:
//   0. Hub Collection URL (from config.toml) — aggregated index
//   1. Hub registries (`hub_registries.json`) — primary source
//   2. Unique `source` fields in the installed-packages manifest
//   3. `AUTO_INSTALL_SOURCES` as fallback seeds (for first run)
//
// GitHub repos are transformed:
//   https://github.com/{owner}/{repo}  →
//   https://raw.githubusercontent.com/{owner}/{repo}/main/hub_index.json

/// Convert a GitHub repo URL to a raw `hub_index.json` URL.
/// Returns `None` for non-GitHub URLs (future: support other hosts).
fn repo_to_index_url(repo_url: &str) -> Option<String> {
    let trimmed = repo_url.trim_end_matches('/').trim_end_matches(".git");
    if let Some(path) = trimmed.strip_prefix("https://github.com/") {
        // path = "owner/repo"
        let parts: Vec<&str> = path.splitn(3, '/').collect();
        if parts.len() >= 2 {
            return Some(format!(
                "https://raw.githubusercontent.com/{}/{}/main/hub_index.json",
                parts[0], parts[1]
            ));
        }
    }
    // Non-GitHub URL: assume it's already a direct index URL
    if trimmed.ends_with(".json") {
        Some(trimmed.to_string())
    } else {
        None
    }
}

/// Collect unique index URLs from config + registries + manifest + bundled seeds.
///
/// Returns `Err` if the installed manifest cannot be read (corrupt JSON /
/// permission denied). The function intentionally surfaces manifest-read
/// failures rather than silently skipping — callers feed these URLs into
/// hub resolution, and a partial URL set is indistinguishable from a
/// corrupt manifest without the signal.
///
/// `warnings` collects non-fatal issues (e.g. config.toml TOML parse failure)
/// that the caller should surface on the MCP wire response.
fn discover_index_urls(
    app_dir: &AppDir,
    warnings: &mut Vec<String>,
) -> Result<Vec<String>, String> {
    let mut index_urls: Vec<String> = Vec::new();

    // 0. From config.toml [hub].collection_url (Tier 0 — aggregated collection).
    // Parse failures (corrupted config) are collected as warnings so the
    // rest of discovery proceeds — the file is optional, but corruption
    // is distinguishable from absence and must be surfaced to the caller.
    match collection_url_from_config(app_dir) {
        Ok(Some(url)) => index_urls.push(url),
        Ok(None) => {}
        Err(e) => warnings.push(format!("config.toml hub.collection_url: {e}")),
    }

    let mut repo_urls: HashSet<String> = HashSet::new();

    // 1. From hub registries (primary). Parse failure is propagated so
    // callers know the registry is degraded — a partial URL set from a
    // corrupt file is indistinguishable from intentionally empty.
    // `HubRegistriesError` is converted to `String` at the wire boundary
    // (`discover_index_urls` still returns `Result<_, String>`).
    let reg = load_registries(app_dir).map_err(|e| e.to_string())?;
    for entry in &reg.registries {
        let normalized = entry.source.trim_end_matches('/').to_string();
        if !normalized.is_empty() {
            repo_urls.insert(normalized);
        }
    }

    // 2. From manifest (catch sources registered before hub_registries existed).
    // Only Git-variant sources can host a remote hub_index.json; other variants
    // (Path / Installed / Bundled / Unknown) are skipped by `git_url()` returning None.
    let m = manifest::load_manifest(app_dir)?;
    for entry in m.packages.values() {
        if let Some(url) = entry.source.git_url() {
            let normalized = url.trim_end_matches('/').to_string();
            if !normalized.is_empty() {
                repo_urls.insert(normalized);
            }
        }
    }

    // 3. Fallback: bundled sources (ensures at least these are checked)
    for url in AUTO_INSTALL_SOURCES {
        repo_urls.insert(url.to_string());
    }

    // 4. Transform repo URLs → index URLs, dedup against Tier 0
    let existing: HashSet<String> = index_urls.iter().cloned().collect();
    let mut derived: Vec<String> = repo_urls
        .iter()
        .filter_map(|url| repo_to_index_url(url))
        .filter(|url| !existing.contains(url))
        .collect();
    derived.sort();
    derived.dedup();
    index_urls.extend(derived);

    Ok(index_urls)
}

// ─── Per-source cache ─────────────────────────────────────────
//
// Each remote index is cached separately at
// `~/.algocline/hub_cache/{hash}.json` where hash is derived from
// the index URL. This avoids mixing data from different registries
// and allows per-source TTL validation.

fn cache_dir(app_dir: &AppDir) -> PathBuf {
    app_dir.hub_cache_dir()
}

fn cache_key(url: &str) -> String {
    // Simple hash: use the URL bytes to produce a stable hex string.
    // Avoids pulling in a hash crate — good enough for cache file naming.
    let mut h: u64 = 0xcbf2_9ce4_8422_2325; // FNV-1a offset basis
    for b in url.as_bytes() {
        h ^= *b as u64;
        h = h.wrapping_mul(0x0100_0000_01b3); // FNV prime
    }
    format!("{h:016x}")
}

/// Result of a cache lookup distinguishing absent, stale, fresh, and corrupt.
///
/// Used by `load_cached_full` (called from `aggregate_index`) to allow
/// stale data to be merged into the aggregate while a warning is emitted.
/// `load_cached` (used by `fetch_one`) maps both `NotPresent` and `Stale`
/// to `Ok(None)` for backward compat.
enum CacheLookup {
    /// File absent.
    NotPresent,
    /// File present but older than `CACHE_TTL_SECS`; contains the stale data.
    Stale(HubIndex),
    /// File present, within TTL, parsed cleanly.
    Fresh(HubIndex),
    /// File present (within TTL) but JSON parse failed.
    Corrupt(String),
}

/// Full cache lookup that distinguishes stale from absent.
///
/// Used by `aggregate_index` so stale data can still be merged with a
/// warning, rather than being silently discarded.
fn load_cached_full(app_dir: &AppDir, url: &str) -> CacheLookup {
    let dir = cache_dir(app_dir);
    let path = dir.join(format!("{}.json", cache_key(url)));
    if !path.exists() {
        return CacheLookup::NotPresent;
    }
    let metadata = match std::fs::metadata(&path) {
        Ok(m) => m,
        Err(_) => return CacheLookup::NotPresent,
    };
    let age = match metadata.modified().ok().and_then(|t| t.elapsed().ok()) {
        Some(a) => a,
        None => return CacheLookup::NotPresent,
    };
    let content = match std::fs::read_to_string(&path) {
        Ok(c) => c,
        Err(e) => return CacheLookup::Corrupt(format!("hub cache read {}: {e}", path.display())),
    };
    match serde_json::from_str::<HubIndex>(&content) {
        Ok(index) => {
            if age.as_secs() > CACHE_TTL_SECS {
                CacheLookup::Stale(index)
            } else {
                CacheLookup::Fresh(index)
            }
        }
        Err(e) => CacheLookup::Corrupt(format!("hub cache parse {}: {e}", path.display())),
    }
}

/// Load cached remote index for a specific URL if fresh (within TTL).
///
/// Returns:
/// - `Ok(Some(index))` — cache hit: file exists, within TTL, parses cleanly.
/// - `Ok(None)` — cache miss: file absent, expired, or metadata unreadable (treat as miss).
/// - `Err(msg)` — file exists and is within TTL but JSON parse fails (corruption);
///   caller should surface as warning and fall back to a network fetch.
fn load_cached(app_dir: &AppDir, url: &str) -> Result<Option<HubIndex>, String> {
    match load_cached_full(app_dir, url) {
        CacheLookup::Fresh(index) => Ok(Some(index)),
        CacheLookup::NotPresent | CacheLookup::Stale(_) => Ok(None),
        CacheLookup::Corrupt(msg) => Err(msg),
    }
}

/// Save remote index to per-source cache file.
///
/// Returns `Ok(())` on success. Cache write failures are returned as
/// `Err(String)`; the caller (`fetch_one`) carries them out of band so
/// hub fetch still completes (the index is in memory) but the warning
/// surfaces to the MCP wire response via the existing `warnings` channel.
fn save_cached(app_dir: &AppDir, url: &str, index: &HubIndex) -> Result<(), String> {
    let dir = cache_dir(app_dir);
    std::fs::create_dir_all(&dir)
        .map_err(|e| format!("failed to create hub cache dir {}: {e}", dir.display()))?;
    let path = dir.join(format!("{}.json", cache_key(url)));
    let json = serde_json::to_string_pretty(index)
        .map_err(|e| format!("failed to serialize hub cache: {e}"))?;
    std::fs::write(&path, json)
        .map_err(|e| format!("failed to write hub cache {}: {e}", path.display()))
}

// ─── Remote fetch ──────────────────────────────────────────────

/// Fetch a single remote index by URL, using per-source cache.
///
/// Returns the index plus an optional cache-related warning. The warning
/// is non-None when either:
/// - The network fetch succeeded but persisting the cache to disk failed.
/// - The cache file was present and within TTL but failed to parse
///   (corruption); in that case the function falls back to a network
///   fetch and includes the parse-failure in the warning so the operator
///   can investigate the on-disk state.
fn fetch_one(app_dir: &AppDir, url: &str) -> Result<(HubIndex, Option<String>), String> {
    // Distinguish cache corruption (Err) from cache miss (Ok(None)).
    match load_cached(app_dir, url) {
        Ok(Some(cached)) => return Ok((cached, None)),
        Ok(None) => {} // cache miss — proceed to network fetch
        Err(e) => {
            // Cache file is corrupt. Fall through to network fetch and
            // carry the corruption warning so the caller can surface it.
            // We don't return Err here because the network path may still succeed.
            let warn = format!("hub cache corrupted for {url}: {e}; falling back to network");
            // Attempt network fetch; on success, attach the cache-corruption warning.
            return fetch_one_from_network(app_dir, url)
                .map(|(idx, save_warn)| {
                    // Prefer the corruption warning; save_warn is secondary.
                    let combined = Some(match save_warn {
                        Some(sw) => format!("{warn}; {sw}"),
                        None => warn.clone(),
                    });
                    (idx, combined)
                })
                .map_err(|fetch_err| format!("{warn}; network fetch also failed: {fetch_err}"));
        }
    }

    fetch_one_from_network(app_dir, url)
}

/// Network-only path for fetching a remote index (no cache read).
///
/// On success returns `(index, Option<cache_write_warning>)`.
fn fetch_one_from_network(
    app_dir: &AppDir,
    url: &str,
) -> Result<(HubIndex, Option<String>), String> {
    let agent = ureq::Agent::new_with_config(
        ureq::config::Config::builder()
            .timeout_global(Some(HTTP_TIMEOUT))
            .build(),
    );
    let body: String = agent
        .get(url)
        .call()
        .map_err(|e| format!("Failed to fetch {url}: {e}"))?
        .body_mut()
        .read_to_string()
        .map_err(|e| format!("Failed to read response from {url}: {e}"))?;

    let index: HubIndex = serde_json::from_str(&body)
        .map_err(|e| format!("Failed to parse index from {url}: {e}"))?;

    let cache_warning = save_cached(app_dir, url, &index)
        .err()
        .map(|e| format!("hub cache write for {url}: {e}"));
    Ok((index, cache_warning))
}

/// Fetch all discovered remote indices and merge into one.
/// Falls back gracefully: failed sources are skipped with warnings.
fn fetch_remote_indices(app_dir: &AppDir) -> Result<(HubIndex, Vec<String>), String> {
    let mut warnings: Vec<String> = Vec::new();
    let urls = discover_index_urls(app_dir, &mut warnings)?;
    let mut all_packages: Vec<IndexEntry> = Vec::new();
    let mut seen_names: HashSet<String> = HashSet::new();

    for url in &urls {
        match fetch_one(app_dir, url) {
            Ok((index, cache_warning)) => {
                for entry in index.packages {
                    if seen_names.insert(entry.entity.name.clone()) {
                        all_packages.push(entry);
                    }
                    // If duplicate name across sources, first wins
                }
                if let Some(w) = cache_warning {
                    warnings.push(w);
                }
            }
            Err(e) => {
                warnings.push(e);
            }
        }
    }

    if all_packages.is_empty() && !warnings.is_empty() {
        warnings.insert(
            0,
            "all remote indices unavailable, showing local packages only".to_string(),
        );
    }

    let merged = HubIndex {
        schema_version: "hub_index/v0".into(),
        updated_at: String::new(),
        packages: all_packages,
    };
    Ok((merged, warnings))
}

// ─── Local state ───────────────────────────────────────────────

/// Build a set of locally installed package names from `installed.json`
/// and the `~/.algocline/packages/` directory.
fn installed_packages(app_dir: &AppDir) -> Result<HashMap<String, Option<String>>, String> {
    let mut map = HashMap::new();

    // From manifest (has version info)
    let m = manifest::load_manifest(app_dir)?;
    for (name, entry) in &m.packages {
        map.insert(name.clone(), entry.version.clone());
    }

    // Also scan packages/ dir in case manifest is stale
    let pkg_dir = app_dir.packages_dir();
    if let Ok(entries) = std::fs::read_dir(&pkg_dir) {
        for entry in entries.flatten() {
            if entry.path().is_dir() {
                if let Some(name) = entry.file_name().to_str() {
                    map.entry(name.to_string()).or_insert(None);
                }
            }
        }
    }

    Ok(map)
}

/// Count local cards per package from `{app_dir}/cards/{pkg}/`.
fn local_card_counts(app_dir: &AppDir) -> HashMap<String, usize> {
    let mut map = HashMap::new();
    let cards_dir = app_dir.cards_dir();
    let entries = match std::fs::read_dir(&cards_dir) {
        Ok(e) => e,
        Err(_) => return map,
    };
    for entry in entries.flatten() {
        if !entry.path().is_dir() {
            continue;
        }
        let pkg = match entry.file_name().to_str() {
            Some(n) => n.to_string(),
            None => continue,
        };
        let count = std::fs::read_dir(entry.path())
            .map(|es| {
                es.flatten()
                    .filter(|e| e.path().extension().is_some_and(|ext| ext == "toml"))
                    .count()
            })
            .unwrap_or(0);
        if count > 0 {
            map.insert(pkg, count);
        }
    }
    map
}

/// Count eval results for a specific package by scanning `{app_dir}/evals/`.
///
/// Reads only `.meta.json` files (lightweight) to check the strategy field.
/// Falls back to reading full eval JSON if meta is missing.
///
/// `warnings` receives per-file corruption messages (read or parse failures).
/// I/O errors on the directory itself return 0 silently (evals dir absent is
/// a legitimate "no evals yet" state). Per-file errors that indicate corruption
/// (file exists but is unreadable or unparseable) are pushed to `warnings` so
/// the caller can surface them on the MCP wire response.
fn count_evals_for_pkg(app_dir: &AppDir, pkg: &str, warnings: &mut Vec<String>) -> usize {
    let evals_dir = app_dir.evals_dir();
    let entries = match std::fs::read_dir(&evals_dir) {
        Ok(e) => e,
        Err(_) => return 0,
    };

    // Collect all filenames first so ordering doesn't matter.
    // We track stems that have a .meta.json to avoid reading the full eval JSON.
    let mut meta_stems: HashSet<String> = HashSet::new();
    let mut meta_matches: usize = 0;
    let mut non_meta_paths: Vec<(PathBuf, String)> = Vec::new(); // (path, stem)

    for entry in entries.flatten() {
        let path = entry.path();
        let name = match path.file_name().and_then(|n| n.to_str()) {
            Some(n) => n.to_string(),
            None => continue,
        };

        if name.ends_with(".meta.json") {
            let stem = name.trim_end_matches(".meta.json").to_string();
            meta_stems.insert(stem.clone());
            // Distinguish I/O failure from parse failure so corruption is visible.
            match std::fs::read_to_string(&path) {
                Ok(content) => match serde_json::from_str::<serde_json::Value>(&content) {
                    Ok(val) => {
                        if val.get("strategy").and_then(|s| s.as_str()) == Some(pkg) {
                            meta_matches += 1;
                        }
                    }
                    Err(e) => warnings.push(format!("eval meta parse {}: {e}", path.display())),
                },
                Err(e) => warnings.push(format!("eval meta read {}: {e}", path.display())),
            }
            continue;
        }

        // Skip non-json or comparison files
        if !name.ends_with(".json") || name.starts_with("compare_") {
            continue;
        }

        let stem = path
            .file_stem()
            .and_then(|s| s.to_str())
            .unwrap_or("")
            .to_string();
        non_meta_paths.push((path, stem));
    }

    // Only read full eval JSON for entries without a .meta.json.
    // Distinguish I/O and parse failures; both are surfaced as warnings.
    let mut fallback_matches: usize = 0;
    for (path, stem) in &non_meta_paths {
        if meta_stems.contains(stem) {
            continue;
        }
        match std::fs::read_to_string(path) {
            Ok(c) => match serde_json::from_str::<serde_json::Value>(&c) {
                Ok(v) => {
                    if v.get("strategy").and_then(|s| s.as_str()) == Some(pkg) {
                        fallback_matches += 1;
                    }
                }
                Err(e) => warnings.push(format!("eval result parse {}: {e}", path.display())),
            },
            Err(e) => warnings.push(format!("eval result read {}: {e}", path.display())),
        }
    }

    meta_matches + fallback_matches
}

// ─── Merge ─────────────────────────────────────────────────────

/// Merge remote index with local install state.
///
/// When a package is installed locally and the remote index lacks a
/// docstring (pre-v0.21 indices), the docstring is extracted from the
/// local `init.lua` so that full-text search works immediately.
fn merge(app_dir: &AppDir, remote: &HubIndex) -> Result<Vec<SearchResult>, String> {
    let installed = installed_packages(app_dir)?;
    let card_counts = local_card_counts(app_dir);
    let pkg_dir: Option<PathBuf> = Some(app_dir.packages_dir());

    let mut seen: HashSet<String> = HashSet::new();
    let mut results: Vec<SearchResult> = Vec::new();

    for entry in &remote.packages {
        let pkg_name = &entry.entity.name;
        let is_installed = installed.contains_key(pkg_name);
        let local_cards = card_counts.get(pkg_name).copied().unwrap_or(0);

        // Supplement empty docstring from local init.lua when installed.
        // Re-parse via `PkgEntity` so the supplementation path stays
        // consistent with `build_index`.
        let docstring = if entry.entity.docstring.as_deref().unwrap_or("").is_empty()
            && is_installed
        {
            pkg_dir
                .as_ref()
                .and_then(|d| PkgEntity::parse_from_init_lua(&d.join(pkg_name).join("init.lua")))
                .and_then(|e| e.docstring)
        } else {
            entry.entity.docstring.clone()
        };

        seen.insert(pkg_name.clone());
        let mut merged_entity = entry.entity.clone();
        merged_entity.docstring = docstring;
        results.push(SearchResult {
            entity: merged_entity,
            source: entry.source.clone(),
            installed: is_installed,
            card_count: if is_installed && local_cards > entry.card_count {
                local_cards
            } else {
                entry.card_count
            },
            best_card: entry.best_card.clone(),
            docstring_matched: None,
        });
    }

    // Add local-only packages (not in remote index).
    for (name, version) in &installed {
        if seen.contains(name) {
            continue;
        }
        // Pull full `PkgEntity` from local init.lua when available (keeps the
        // wire shape consistent with remote entries). When the package does
        // not parse as a `PkgEntity` (missing `M.meta.name`), fall back to
        // a minimal entity with just the directory name and the manifest
        // version — the entry still appears in local-only listings, but the
        // richer projection fields are simply absent.
        let parsed_entity = pkg_dir
            .as_ref()
            .and_then(|d| PkgEntity::parse_from_init_lua(&d.join(name).join("init.lua")));
        let entity = parsed_entity.unwrap_or(PkgEntity {
            name: name.clone(),
            version: version.clone(),
            description: None,
            category: None,
            docstring: None,
        });
        results.push(SearchResult {
            entity,
            source: PackageSource::Unknown,
            installed: true,
            card_count: card_counts.get(name).copied().unwrap_or(0),
            best_card: None,
            docstring_matched: None,
        });
    }

    Ok(results)
}

// ─── Search (filtering) ───────────────────────────────────────

fn matches_query(result: &SearchResult, query: &str) -> bool {
    let q = query.to_lowercase();
    let pkg = &result.entity;
    let empty = String::new();
    pkg.name.to_lowercase().contains(&q)
        || pkg
            .description
            .as_ref()
            .unwrap_or(&empty)
            .to_lowercase()
            .contains(&q)
        || pkg
            .category
            .as_ref()
            .unwrap_or(&empty)
            .to_lowercase()
            .contains(&q)
        || pkg
            .docstring
            .as_ref()
            .unwrap_or(&empty)
            .to_lowercase()
            .contains(&q)
}

// ─── Index generation (reindex) ───────────────────────────────
//
// The non-Lua-VM parser that used to live here
// (`parse_meta_from_init_lua` / `extract_docstring`) has moved into
// `algocline_core::PkgEntity::parse_from_init_lua`, where it is shared
// with the manifest / lockfile wire format. The parsing tests migrated
// with it; `hub.rs` now just consumes the typed `PkgEntity` projection.

/// Build a hub index by scanning a packages directory.
///
/// When `source_dir` is provided, scans that directory directly
/// (for generating an index from a repo checkout).  Metadata comes
/// only from `init.lua` — no manifest lookup, no card counts.
///
/// When `source_dir` is `None`, scans `~/.algocline/packages/` and
/// enriches entries with manifest source and local card counts.
fn build_index(app_dir: &AppDir, source_dir: Option<&std::path::Path>) -> Result<HubIndex, String> {
    let empty = || HubIndex {
        schema_version: "hub_index/v0".into(),
        updated_at: super::manifest::now_iso8601(),
        packages: Vec::new(),
    };

    let pkg_dir = match source_dir {
        Some(d) => d.to_path_buf(),
        None => app_dir.packages_dir(),
    };

    let use_local_state = source_dir.is_none();
    let card_counts = if use_local_state {
        local_card_counts(app_dir)
    } else {
        HashMap::new()
    };
    // Manifest read errors surface as `Err` rather than degrading to an
    // empty manifest — when building the local hub index, a corrupt
    // `installed.json` silently turning all package sources into
    // `PackageSource::Unknown` would be indistinguishable from the
    // legitimate "no source recorded" state, and would ship into
    // generated `hub_index.json` files verbatim.
    let manifest = if use_local_state {
        manifest::load_manifest(app_dir)?
    } else {
        manifest::Manifest::default()
    };

    let mut entries = Vec::new();

    // Missing / unreadable `pkg_dir` is a legitimate "no packages yet"
    // state on a fresh install — distinct from manifest corruption
    // above, and safe to surface as an empty index.
    let dir_entries = match std::fs::read_dir(&pkg_dir) {
        Ok(e) => e,
        Err(_) => return Ok(empty()),
    };

    for entry in dir_entries.flatten() {
        if !entry.path().is_dir() {
            continue;
        }
        let dir_name = match entry.file_name().to_str() {
            Some(n) if !n.starts_with('.') && !n.starts_with('_') => n.to_string(),
            _ => continue,
        };

        let init_lua = entry.path().join("init.lua");
        if !init_lua.exists() {
            continue;
        }

        // Silent-exclude gate: `PkgEntity::parse_from_init_lua` returns `None`
        // when `M.meta` is absent or `M.meta.name` is empty. Directories that
        // happen to contain an `init.lua` but aren't algocline packages
        // (e.g. `alc_shapes/`, a type DSL library) are dropped from the index
        // rather than falling through with a placeholder name — that would
        // pollute hub_search.
        let Some(entity) = PkgEntity::parse_from_init_lua(&init_lua) else {
            continue;
        };

        // Use manifest source only for local-state mode. When the manifest
        // has no record for this directory, default to `PackageSource::Unknown`
        // (via `Default`) — hub consumers see it as "source not recorded".
        let source = manifest
            .packages
            .get(&dir_name)
            .map(|e| e.source.clone())
            .unwrap_or_default();

        entries.push(IndexEntry {
            entity,
            source,
            card_count: card_counts.get(&dir_name).copied().unwrap_or(0),
            best_card: None,
        });
    }

    entries.sort_by(|a, b| a.entity.name.cmp(&b.entity.name));

    Ok(HubIndex {
        schema_version: "hub_index/v0".into(),
        updated_at: super::manifest::now_iso8601(),
        packages: entries,
    })
}

// ─── Public API ────────────────────────────────────────────────

impl AppService {
    /// Generate a hub index from a packages directory.
    ///
    /// When `source_dir` is provided, scans that directory (e.g. a
    /// repo checkout) — pure metadata extraction, no manifest or card
    /// data mixed in.  When omitted, scans `~/.algocline/packages/`.
    ///
    /// Writes the index to `output_path` (for CI / publishing).
    /// Does NOT touch the remote search cache.
    pub fn hub_reindex(
        &self,
        output_path: Option<&str>,
        source_dir: Option<&str>,
    ) -> Result<String, String> {
        let src = source_dir.map(std::path::Path::new);
        if let Some(d) = src {
            if !d.is_dir() {
                return Err(format!("source_dir '{}' is not a directory", d.display()));
            }
        }
        let app_dir = self.log_config.app_dir();
        let index = build_index(&app_dir, src)?;

        let written_path = if let Some(path) = output_path {
            let json = serde_json::to_string_pretty(&index)
                .map_err(|e| format!("Failed to serialize index: {e}"))?;
            std::fs::write(path, &json)
                .map_err(|e| format!("Failed to write index to {path}: {e}"))?;
            Some(path.to_string())
        } else {
            None
        };

        let response = serde_json::json!({
            "package_count": index.packages.len(),
            "updated_at": index.updated_at,
            "output_path": written_path,
            "source_dir": source_dir,
        });
        Ok(response.to_string())
    }

    /// Show detailed information for a single package.
    ///
    /// Aggregates package metadata (from index or local `init.lua`),
    /// all Cards, aliases, and eval stats into one response.
    pub fn hub_info(&self, pkg: &str) -> Result<String, String> {
        use algocline_engine::card;

        // Guard against path traversal
        if pkg.contains("..") || pkg.contains('/') || pkg.contains('\\') {
            return Err(format!("Invalid package name: '{pkg}'"));
        }

        // Package metadata: try remote index first, fall back to local
        let app_dir = self.log_config.app_dir();
        let installed = installed_packages(&app_dir)?;
        let is_installed = installed.contains_key(pkg);

        // Resolve package metadata: try remote index first, fall back to
        // local init.lua. `version` / `description` / `category` are modelled
        // as `Option<String>` at the `PkgEntity` layer; at this API surface
        // we flatten `None` to empty string so the wire shape (non-null
        // JSON string fields) stays unchanged for existing consumers.
        let (version, description, category, source) = {
            let (remote, _) = fetch_remote_indices(&app_dir)?;
            if let Some(entry) = remote.packages.iter().find(|e| e.entity.name == pkg) {
                (
                    entry.entity.version.clone().unwrap_or_default(),
                    entry.entity.description.clone().unwrap_or_default(),
                    entry.entity.category.clone().unwrap_or_default(),
                    entry.source.clone(),
                )
            } else if is_installed {
                // Fall back to local init.lua parse via `PkgEntity`. When
                // the file is not a valid package (no `M.meta.name`), we
                // degrade gracefully by returning the manifest-recorded
                // version and empty string fields — mirroring the pre-typed
                // behaviour.
                let init_lua = app_dir.packages_dir().join(pkg).join("init.lua");
                let entity = PkgEntity::parse_from_init_lua(&init_lua);
                let manifest_source = manifest::load_manifest(&app_dir)?
                    .packages
                    .get(pkg)
                    .map(|e| e.source.clone())
                    .unwrap_or_default();
                match entity {
                    Some(e) => (
                        e.version.unwrap_or_default(),
                        e.description.unwrap_or_default(),
                        e.category.unwrap_or_default(),
                        manifest_source,
                    ),
                    None => (
                        installed.get(pkg).cloned().flatten().unwrap_or_default(),
                        String::new(),
                        String::new(),
                        manifest_source,
                    ),
                }
            } else {
                return Err(format!(
                    "Package '{pkg}' not found in remote indices or locally installed packages"
                ));
            }
        };

        // Collect warnings additively; surfaced in response JSON so MCP callers
        // (Claude Code UI) observe degraded data instead of silent loss.
        // See CLAUDE.md §Service 層の Error 伝播規律 — tracing alone is not enough.
        let mut warnings: Vec<String> = Vec::new();

        // Cards for this package (single call, reused for stats)
        let card_rows = match self.card_store.list(Some(pkg)) {
            Ok(rows) => rows,
            Err(e) => {
                let msg = format!("card store list for '{pkg}': {e}");
                tracing::warn!("{}", msg);
                warnings.push(msg);
                vec![]
            }
        };
        let cards_json = card::summaries_to_json(&card_rows);

        // Aliases for this package
        let aliases_json = match self.card_store.alias_list(Some(pkg)) {
            Ok(rows) => card::aliases_to_json(&rows),
            Err(e) => {
                let msg = format!("card store alias_list for '{pkg}': {e}");
                tracing::warn!("{}", msg);
                warnings.push(msg);
                serde_json::json!([])
            }
        };

        // Stats: card count, best pass_rate, eval count
        let card_count = card_rows.len();
        let best_pass_rate = card_rows
            .iter()
            .filter_map(|c| c.pass_rate)
            .fold(f64::NEG_INFINITY, f64::max);
        let best_pass_rate = if best_pass_rate.is_finite() {
            Some(best_pass_rate)
        } else {
            None
        };

        // Eval count from evals directory; corruption warnings surfaced additively.
        let eval_count = count_evals_for_pkg(&app_dir, pkg, &mut warnings);

        let mut response = serde_json::json!({
            "pkg": {
                "name": pkg,
                "version": version,
                "description": description,
                "category": category,
                "source": source,
                "installed": is_installed,
            },
            "cards": cards_json,
            "aliases": aliases_json,
            "stats": {
                "card_count": card_count,
                "eval_count": eval_count,
                "best_pass_rate": best_pass_rate,
            },
        });
        if !warnings.is_empty() {
            response["warnings"] = serde_json::json!(warnings);
        }
        Ok(response.to_string())
    }

    /// Search packages across remote indices + local state.
    ///
    /// Index URLs are discovered from hub registries, manifest sources,
    /// and `AUTO_INSTALL_SOURCES`. Each source is cached independently.
    ///
    /// ## List-tool options (`opts`)
    ///
    /// The `opts` parameter carries the list-tool primitives
    /// (`limit / sort / filter / fields / verbose`) shared with other
    /// list-style MCP tools. Defaults:
    ///
    /// - `limit` — 50 when `None`. `Some(0)` means **no limit** (return
    ///   all matching entries — empty-means-all idiom).
    /// - `sort` — `"-installed,name"` when `None` (installed first, then
    ///   ascending by name).
    /// - `filter` — no additional filter. Legacy `category` /
    ///   `installed_only` parameters are merged into the filter map when
    ///   `filter` does not already contain those keys (explicit
    ///   `filter` wins on conflict).
    /// - `fields` / `verbose` — projection is applied to every entry in
    ///   the `results` array (see
    ///   [`super::list_opts::resolve_fields`]). Top-level keys
    ///   (`total`, `sources`, `warnings`) are never projected away.
    ///
    /// ## docstring handling
    ///
    /// [`SearchResult::docstring`] is `skip_serializing`, so it is
    /// absent from the default serialized view. When the resolved
    /// projection contains `"docstring"`, it is re-injected into the
    /// per-entry JSON via
    /// [`SearchResult::to_value_with_optional_docstring`].
    pub(crate) fn hub_search(
        &self,
        query: Option<&str>,
        category: Option<&str>,
        installed_only: Option<bool>,
        opts: ListOpts,
    ) -> Result<String, String> {
        let app_dir = self.log_config.app_dir();
        let (remote, warnings) = fetch_remote_indices(&app_dir)?;
        let mut results = merge(&app_dir, &remote)?;

        // Filter by query (internal signal covers name/description/
        // category/docstring — `matches_query` unchanged).
        let query_lower = query.filter(|q| !q.is_empty()).map(|q| q.to_lowercase());
        if let Some(ref ql) = query_lower {
            results.retain(|r| matches_query(r, ql));
        }

        // Compute docstring_matched per remaining hit: Some(true) only
        // when the query matched docstring and none of {name,
        // description, category}; otherwise None.
        if let Some(ref ql) = query_lower {
            for r in &mut results {
                let empty = String::new();
                let pkg = &r.entity;
                let other_hit = pkg.name.to_lowercase().contains(ql)
                    || pkg
                        .description
                        .as_ref()
                        .unwrap_or(&empty)
                        .to_lowercase()
                        .contains(ql)
                    || pkg
                        .category
                        .as_ref()
                        .unwrap_or(&empty)
                        .to_lowercase()
                        .contains(ql);
                let doc_hit = pkg
                    .docstring
                    .as_ref()
                    .unwrap_or(&empty)
                    .to_lowercase()
                    .contains(ql);
                r.docstring_matched = if !other_hit && doc_hit {
                    Some(true)
                } else {
                    None
                };
            }
        }

        // Build the effective filter map: start from explicit `opts.filter`,
        // then fold legacy `category` / `installed_only` in only if the
        // corresponding key is not already set (explicit filter wins).
        let mut filter_map: std::collections::HashMap<String, serde_json::Value> =
            opts.filter.unwrap_or_default();
        if let Some(cat) = category {
            filter_map
                .entry("category".to_string())
                .or_insert_with(|| serde_json::Value::String(cat.to_string()));
        }
        if let Some(only) = installed_only {
            // Preserve prior semantic: `installed_only=Some(false)` was a
            // no-op (it did not force `installed=false`). Only fold when
            // explicitly true.
            if only {
                filter_map
                    .entry("installed".to_string())
                    .or_insert(serde_json::Value::Bool(true));
            }
        }

        // Resolve sort keys up-front so an invalid sort string errors out
        // before we touch results.
        let sort_str = opts.sort.as_deref().unwrap_or("-installed,name");
        let sort_keys = parse_sort(sort_str)?;

        // Resolve projection fields; this also rejects unknown `verbose`
        // values before any heavy work.
        let fields = resolve_fields(
            opts.verbose.as_deref(),
            opts.fields.as_deref(),
            HUB_SEARCH_SUMMARY,
            HUB_SEARCH_FULL,
        )?;
        let include_docstring = fields.iter().any(|f| f == "docstring");

        // Serialize each result to a Value (docstring optionally attached)
        // so filter/sort/projection work uniformly on JSON values.
        let mut items: Vec<serde_json::Value> = results
            .iter()
            .map(|r| r.to_value_with_optional_docstring(include_docstring))
            .collect();

        // Filter AFTER serialization so filter keys can reference
        // projection-level shape (e.g. `category`, `installed`).
        if !filter_map.is_empty() {
            items.retain(|v| matches_filter(v, &filter_map));
        }

        // Sort.
        apply_sort_by_value(&mut items, &sort_keys);

        // Limit. `limit = Some(0)` means "no limit" (return all results)
        // — mirrors the `empty=all & some=filter` idiom used across the
        // list-tool contract. `None` falls back to the default cap (50).
        let total = items.len();
        let limit = opts.limit.unwrap_or(50);
        if limit > 0 {
            items.truncate(limit);
        }

        // Projection (after truncation — unselected fields are stripped
        // from the kept entries only).
        let projected: Vec<serde_json::Value> = items
            .into_iter()
            .map(|v| project_fields(v, &fields))
            .collect();

        // Collect discovered sources for transparency.
        // Warnings from this call (e.g. config.toml parse failure) are
        // already present in `warnings` from `fetch_remote_indices` above;
        // use a throwaway buffer here to avoid duplicating them.
        let mut _src_warnings: Vec<String> = Vec::new();
        let sources = discover_index_urls(&app_dir, &mut _src_warnings)?;

        let mut json = serde_json::json!({
            "results": projected,
            "total": total,
            "sources": sources,
        });
        if !warnings.is_empty() {
            json["warnings"] = serde_json::json!(warnings);
        }
        Ok(json.to_string())
    }

    /// Aggregate hub index across all discovered cache sources.
    ///
    /// Reads the cached `hub_index.json` for each registered source URL
    /// (cache-only, no network fetch). Sources that are missing from cache
    /// or whose cache file is corrupt are skipped and a warning is collected;
    /// the aggregate still succeeds with the remaining sources.
    ///
    /// Registry-load failures (corrupt `hub_registries.json`) are also
    /// demoted to warnings rather than hard errors. Any warnings accumulated
    /// before the failure are preserved in the returned `warnings` vec so
    /// they reach the MCP wire response.
    ///
    /// # Returns
    /// `Ok((merged_index, warnings))` — always Ok; `warnings` contains any
    /// per-source failure messages including registry-load failures.
    pub(crate) fn aggregate_index(
        &self,
    ) -> Result<(HubIndex, Vec<String>), super::error::ServiceError> {
        let app_dir = self.log_config.app_dir();
        let mut warnings: Vec<String> = Vec::new();

        // Discover source URLs (registries + manifest + seeds).
        // On failure, demote the error to a warning and return a degraded
        // (empty) response. Preserves any warnings already collected
        // (e.g. config.toml parse warning) before the failure.
        let urls = match discover_index_urls(&app_dir, &mut warnings) {
            Ok(u) => u,
            Err(e) => {
                warnings.push(format!("hub registry discovery failed: {e}"));
                return Ok((
                    HubIndex {
                        schema_version: "hub_index/v0".into(),
                        updated_at: String::new(),
                        packages: Vec::new(),
                    },
                    warnings,
                ));
            }
        };

        // Empty URL list: return empty index (not an error — fresh install).
        if urls.is_empty() {
            return Ok((
                HubIndex {
                    schema_version: "hub_index/v0".into(),
                    updated_at: String::new(),
                    packages: Vec::new(),
                },
                warnings,
            ));
        }

        // Load each source from cache. Network fetches are intentionally
        // avoided here: resource reads happen synchronously in the MCP
        // request path and should not block on network I/O. The cache
        // is populated by hub_reindex / hub_search (which do fetch).
        // Per-source load failures are best-effort: collect as warnings
        // and continue with remaining sources.
        let mut all_packages: Vec<IndexEntry> = Vec::new();
        let mut seen_names: std::collections::HashSet<String> = std::collections::HashSet::new();

        for url in &urls {
            let merge_packages =
                |packages: Vec<IndexEntry>,
                 all: &mut Vec<IndexEntry>,
                 seen: &mut std::collections::HashSet<String>| {
                    for entry in packages {
                        if seen.insert(entry.entity.name.clone()) {
                            all.push(entry);
                        }
                    }
                };
            match load_cached_full(&app_dir, url) {
                CacheLookup::Fresh(index) => {
                    merge_packages(index.packages, &mut all_packages, &mut seen_names);
                }
                CacheLookup::Stale(index) => {
                    // Stale but not absent: merge the data and emit a warning so
                    // the caller knows the catalog may be outdated.
                    warnings.push(format!(
                        "hub cache stale (>{CACHE_TTL_SECS}s) for {url}; run alc_hub_search to refresh"
                    ));
                    merge_packages(index.packages, &mut all_packages, &mut seen_names);
                }
                CacheLookup::NotPresent => {
                    // Cache file absent — not an error, just skip.
                }
                CacheLookup::Corrupt(e) => {
                    // Cache corruption: surface as warning, continue aggregate.
                    warnings.push(format!("hub cache read failed for {url}: {e}"));
                }
            }
        }

        Ok((
            HubIndex {
                schema_version: "hub_index/v0".into(),
                updated_at: String::new(),
                packages: all_packages,
            },
            warnings,
        ))
    }
}

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

    #[test]
    fn repo_to_index_url_github() {
        assert_eq!(
            repo_to_index_url("https://github.com/ynishi/algocline-bundled-packages"),
            Some(
                "https://raw.githubusercontent.com/ynishi/algocline-bundled-packages/main/hub_index.json"
                    .to_string()
            )
        );
    }

    #[test]
    fn repo_to_index_url_github_trailing_slash() {
        assert_eq!(
            repo_to_index_url("https://github.com/user/repo/"),
            Some("https://raw.githubusercontent.com/user/repo/main/hub_index.json".to_string())
        );
    }

    #[test]
    fn repo_to_index_url_github_dot_git() {
        assert_eq!(
            repo_to_index_url("https://github.com/user/repo.git"),
            Some("https://raw.githubusercontent.com/user/repo/main/hub_index.json".to_string())
        );
    }

    #[test]
    fn repo_to_index_url_direct_json() {
        assert_eq!(
            repo_to_index_url("https://example.com/my_index.json"),
            Some("https://example.com/my_index.json".to_string())
        );
    }

    #[test]
    fn repo_to_index_url_unknown_host_no_json() {
        assert_eq!(repo_to_index_url("https://example.com/some-repo"), None);
    }

    #[test]
    fn repo_to_index_url_local_path() {
        assert_eq!(repo_to_index_url("/home/user/my-pkg"), None);
    }

    #[test]
    fn cache_key_stable() {
        let k1 = cache_key("https://example.com/index.json");
        let k2 = cache_key("https://example.com/index.json");
        assert_eq!(k1, k2);
        assert_eq!(k1.len(), 16); // 16 hex chars
    }

    #[test]
    fn cache_key_different_urls() {
        let k1 = cache_key("https://a.com/index.json");
        let k2 = cache_key("https://b.com/index.json");
        assert_ne!(k1, k2);
    }

    // NOTE: The init.lua meta / docstring parsing tests have moved to
    // `algocline_core::pkg::tests` along with the parser itself. The
    // `hub.rs` call-path tests now exercise the typed `PkgEntity` via
    // `build_index` / `merge` only.

    #[test]
    fn merge_dedup_uses_hashset() {
        // Verify that merge correctly handles local-only packages
        // without O(n*m) behavior (structural test).
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let remote = HubIndex {
            schema_version: "hub_index/v0".into(),
            updated_at: String::new(),
            packages: vec![IndexEntry {
                entity: PkgEntity {
                    name: "remote_only".into(),
                    version: Some("1.0".into()),
                    description: Some("from remote".into()),
                    category: Some("test".into()),
                    docstring: None,
                },
                source: PackageSource::Unknown,
                card_count: 0,
                best_card: None,
            }],
        };

        let results = merge(&app_dir, &remote).expect("merge over empty app_dir should succeed");
        // Should include remote_only + any locally installed packages
        assert!(results.iter().any(|r| r.entity.name == "remote_only"));
    }

    #[test]
    fn matches_query_searches_docstring() {
        let result = SearchResult {
            entity: PkgEntity {
                name: "cascade".into(),
                version: Some("0.1.0".into()),
                description: Some("Multi-level routing".into()),
                category: Some("meta".into()),
                docstring: Some("Based on FrugalGPT. Uses Thompson Sampling.".into()),
            },
            source: PackageSource::Unknown,
            installed: true,
            card_count: 0,
            best_card: None,
            docstring_matched: None,
        };

        assert!(matches_query(&result, "thompson"), "docstring match");
        assert!(matches_query(&result, "FrugalGPT"), "docstring match case");
        assert!(matches_query(&result, "routing"), "description match");
        assert!(!matches_query(&result, "bayesian"), "no match");
    }

    // ─── SearchResult::to_value_with_optional_docstring ────────────
    //
    // `docstring` is not emitted by the default serde path (via the
    // `serialize_entity_without_docstring` custom serializer) and is
    // re-attached only when the projection path says so. These tests
    // pin the two branches of that helper — they are the hinge that
    // `verbose="full"` / `fields=["docstring"]` rely on.

    fn sample_search_result() -> SearchResult {
        SearchResult {
            entity: PkgEntity {
                name: "cascade".into(),
                version: Some("0.1.0".into()),
                description: Some("Multi-level routing".into()),
                category: Some("reasoning".into()),
                docstring: Some("Based on FrugalGPT. Uses Thompson Sampling.".into()),
            },
            source: PackageSource::Git {
                url: "https://example.com/cascade".into(),
                rev: None,
            },
            installed: true,
            card_count: 3,
            best_card: None,
            docstring_matched: None,
        }
    }

    #[test]
    fn to_value_default_omits_docstring() {
        let r = sample_search_result();
        let v = r.to_value_with_optional_docstring(false);
        let obj = v.as_object().expect("object");
        assert!(
            !obj.contains_key("docstring"),
            "default summary must not leak docstring"
        );
        assert_eq!(obj.get("name").and_then(|x| x.as_str()), Some("cascade"));
        // `docstring_matched` is Option<None> → `skip_serializing_if`
        // must omit it when the query did not mark a docstring-only hit.
        assert!(
            !obj.contains_key("docstring_matched"),
            "docstring_matched=None must be omitted"
        );
    }

    #[test]
    fn to_value_include_reattaches_docstring() {
        let r = sample_search_result();
        let v = r.to_value_with_optional_docstring(true);
        let obj = v.as_object().expect("object");
        assert_eq!(
            obj.get("docstring").and_then(|x| x.as_str()),
            Some("Based on FrugalGPT. Uses Thompson Sampling.")
        );
    }

    #[test]
    fn to_value_serializes_docstring_matched_when_set() {
        let mut r = sample_search_result();
        r.docstring_matched = Some(true);
        let v = r.to_value_with_optional_docstring(false);
        let obj = v.as_object().expect("object");
        assert_eq!(
            obj.get("docstring_matched").and_then(|x| x.as_bool()),
            Some(true)
        );
    }

    // ─── projection glue ──────────────────────────────────────────
    //
    // These tests exercise the projection path that `hub_search` uses to
    // shape output: `resolve_fields` + `project_fields` applied to a
    // `to_value_with_optional_docstring`-serialized entry. They pin the
    // wf-sim-verbose contract: `fields` wins over `verbose`, default
    // summary preset excludes docstring, `full` preset includes
    // docstring, unknown keys silently skipped.

    #[test]
    fn hub_search_default_summary_excludes_docstring() {
        let r = sample_search_result();
        let fields = resolve_fields(None, None, HUB_SEARCH_SUMMARY, HUB_SEARCH_FULL).unwrap();
        let include_docstring = fields.iter().any(|f| f == "docstring");
        let v = project_fields(
            r.to_value_with_optional_docstring(include_docstring),
            &fields,
        );
        let obj = v.as_object().expect("object");
        assert!(
            !obj.contains_key("docstring"),
            "summary preset must omit docstring"
        );
        // summary preset fields that are present on the sample entry
        for key in ["name", "version", "description", "category", "installed"] {
            assert!(obj.contains_key(key), "summary preset key {key} missing");
        }
    }

    #[test]
    fn hub_search_verbose_full_includes_docstring() {
        let r = sample_search_result();
        let fields =
            resolve_fields(Some("full"), None, HUB_SEARCH_SUMMARY, HUB_SEARCH_FULL).unwrap();
        let include_docstring = fields.iter().any(|f| f == "docstring");
        let v = project_fields(
            r.to_value_with_optional_docstring(include_docstring),
            &fields,
        );
        let obj = v.as_object().expect("object");
        assert_eq!(
            obj.get("docstring").and_then(|x| x.as_str()),
            Some("Based on FrugalGPT. Uses Thompson Sampling.")
        );
        // full preset superset keys
        for key in ["source", "card_count"] {
            assert!(obj.contains_key(key), "full preset key {key} missing");
        }
    }

    #[test]
    fn hub_search_fields_beats_verbose() {
        let r = sample_search_result();
        let explicit = vec!["name".to_string(), "docstring".to_string()];
        // verbose=summary normally excludes docstring, but explicit
        // fields must win.
        let fields = resolve_fields(
            Some("summary"),
            Some(&explicit),
            HUB_SEARCH_SUMMARY,
            HUB_SEARCH_FULL,
        )
        .unwrap();
        let include_docstring = fields.iter().any(|f| f == "docstring");
        let v = project_fields(
            r.to_value_with_optional_docstring(include_docstring),
            &fields,
        );
        let obj = v.as_object().expect("object");
        assert_eq!(obj.len(), 2, "only the two requested fields");
        assert!(obj.contains_key("name"));
        assert!(obj.contains_key("docstring"));
    }

    #[test]
    fn hub_search_fields_unknown_key_silently_skipped() {
        let r = sample_search_result();
        let explicit = vec!["name".to_string(), "bogus".to_string()];
        let fields =
            resolve_fields(None, Some(&explicit), HUB_SEARCH_SUMMARY, HUB_SEARCH_FULL).unwrap();
        let v = project_fields(r.to_value_with_optional_docstring(false), &fields);
        let obj = v.as_object().expect("object");
        assert_eq!(obj.len(), 1, "bogus must not appear");
        assert!(obj.contains_key("name"));
    }

    #[test]
    fn hub_search_invalid_verbose_errors() {
        let err =
            resolve_fields(Some("fat"), None, HUB_SEARCH_SUMMARY, HUB_SEARCH_FULL).unwrap_err();
        assert!(
            err.contains("fat"),
            "error must mention the offending value"
        );
    }

    // ─── docstring_matched classification ─────────────────────────
    //
    // The query-time classification rule: `docstring_matched = Some(true)`
    // only when the query hit docstring AND missed name/description/
    // category; otherwise `None` (and therefore omitted from output).
    // The logic lives inline in `hub_search`; we re-create it here over a
    // tiny local helper so the three cases stay pinned as a contract.

    fn classify(r: &SearchResult, query: &str) -> Option<bool> {
        let ql = query.to_lowercase();
        if query.is_empty() {
            return None;
        }
        let empty = String::new();
        let pkg = &r.entity;
        let other_hit = pkg.name.to_lowercase().contains(&ql)
            || pkg
                .description
                .as_ref()
                .unwrap_or(&empty)
                .to_lowercase()
                .contains(&ql)
            || pkg
                .category
                .as_ref()
                .unwrap_or(&empty)
                .to_lowercase()
                .contains(&ql);
        let doc_hit = pkg
            .docstring
            .as_ref()
            .unwrap_or(&empty)
            .to_lowercase()
            .contains(&ql);
        if !other_hit && doc_hit {
            Some(true)
        } else {
            None
        }
    }

    #[test]
    fn docstring_matched_true_when_only_docstring_hits() {
        let r = sample_search_result();
        // "Thompson" appears only in docstring of the sample entry.
        assert_eq!(classify(&r, "thompson"), Some(true));
    }

    #[test]
    fn docstring_matched_none_when_name_also_hits() {
        let r = sample_search_result();
        // "cascade" hits the name; docstring match is irrelevant now.
        assert_eq!(classify(&r, "cascade"), None);
    }

    #[test]
    fn docstring_matched_none_when_description_hits() {
        let r = sample_search_result();
        // "routing" hits description; should be None.
        assert_eq!(classify(&r, "routing"), None);
    }

    #[test]
    fn docstring_matched_none_when_query_empty() {
        let r = sample_search_result();
        assert_eq!(classify(&r, ""), None);
    }

    // ─── filter fold (legacy params → filter map) ─────────────────
    //
    // Behavioural rule: legacy `category` / `installed_only=true` fold
    // into the filter map only when the corresponding key is not
    // already set (explicit `filter` wins). `installed_only=false` is a
    // no-op (preserves prior semantics).

    fn build_filter_map(
        category: Option<&str>,
        installed_only: Option<bool>,
        explicit: Option<HashMap<String, serde_json::Value>>,
    ) -> HashMap<String, serde_json::Value> {
        let mut filter_map = explicit.unwrap_or_default();
        if let Some(cat) = category {
            filter_map
                .entry("category".to_string())
                .or_insert_with(|| serde_json::Value::String(cat.to_string()));
        }
        if let Some(only) = installed_only {
            if only {
                filter_map
                    .entry("installed".to_string())
                    .or_insert(serde_json::Value::Bool(true));
            }
        }
        filter_map
    }

    #[test]
    fn filter_by_category_via_legacy_param() {
        let m = build_filter_map(Some("reasoning"), None, None);
        assert_eq!(
            m.get("category"),
            Some(&serde_json::Value::String("reasoning".to_string()))
        );
    }

    #[test]
    fn filter_by_installed_only_via_legacy_param() {
        let m = build_filter_map(None, Some(true), None);
        assert_eq!(m.get("installed"), Some(&serde_json::Value::Bool(true)));
    }

    #[test]
    fn filter_installed_only_false_is_noop() {
        let m = build_filter_map(None, Some(false), None);
        assert!(
            !m.contains_key("installed"),
            "installed_only=false should not fold in"
        );
    }

    #[test]
    fn filter_beats_legacy_param_on_conflict() {
        // Explicit filter says category=meta; legacy says reasoning.
        // Explicit must win.
        let mut explicit = HashMap::new();
        explicit.insert(
            "category".to_string(),
            serde_json::Value::String("meta".to_string()),
        );
        let m = build_filter_map(Some("reasoning"), None, Some(explicit));
        assert_eq!(
            m.get("category"),
            Some(&serde_json::Value::String("meta".to_string()))
        );
    }

    #[test]
    fn filter_merges_legacy_when_no_conflict() {
        // Explicit sets a different key; legacy category should still
        // be folded in.
        let mut explicit = HashMap::new();
        explicit.insert("installed".to_string(), serde_json::Value::Bool(true));
        let m = build_filter_map(Some("reasoning"), None, Some(explicit));
        assert_eq!(
            m.get("category"),
            Some(&serde_json::Value::String("reasoning".to_string()))
        );
        assert_eq!(m.get("installed"), Some(&serde_json::Value::Bool(true)));
    }

    // ─── load_registries: file-absent vs. corrupt JSON ────────────

    #[test]
    fn load_registries_missing_file_returns_default() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        // No hub_registries.json created — must return Ok(empty).
        let result = load_registries(&app_dir);
        assert!(result.is_ok(), "missing file should be Ok: {result:?}");
        assert!(result.unwrap().registries.is_empty());
    }

    #[test]
    fn load_registries_corrupt_json_returns_err() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        // Write corrupt JSON to the registries path.
        let path = app_dir.hub_registries_json();
        std::fs::create_dir_all(path.parent().unwrap()).unwrap();
        std::fs::write(&path, b"not valid json {{{").unwrap();
        let result = load_registries(&app_dir);
        assert!(result.is_err(), "corrupt JSON must propagate Err");
        let msg = result.unwrap_err().to_string();
        assert!(
            msg.contains("parse"),
            "error message should mention parse: {msg}"
        );
    }

    #[test]
    fn load_registries_valid_file_deserializes() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let path = app_dir.hub_registries_json();
        std::fs::create_dir_all(path.parent().unwrap()).unwrap();
        let content = r#"{"registries":[{"source":"https://github.com/user/repo","origin":"pkg_install","added_at":"2026-01-01T00:00:00Z"}]}"#;
        std::fs::write(&path, content).unwrap();
        let result = load_registries(&app_dir);
        assert!(result.is_ok(), "valid JSON must parse Ok: {result:?}");
        let reg = result.unwrap();
        assert_eq!(reg.registries.len(), 1);
        assert_eq!(reg.registries[0].source, "https://github.com/user/repo");
    }

    // ─── default sort verification ────────────────────────────────

    #[test]
    fn default_sort_is_minus_installed_name() {
        let keys = parse_sort("-installed,name").unwrap();
        assert_eq!(keys.len(), 2);
        assert_eq!(keys[0].key, "installed");
        assert!(keys[0].desc, "installed must sort desc (true first)");
        assert_eq!(keys[1].key, "name");
        assert!(!keys[1].desc);

        // Apply it against a small vec and confirm the expected order.
        let mut items = vec![
            serde_json::json!({"installed": false, "name": "zeta"}),
            serde_json::json!({"installed": true, "name": "mu"}),
            serde_json::json!({"installed": false, "name": "alpha"}),
            serde_json::json!({"installed": true, "name": "beta"}),
        ];
        apply_sort_by_value(&mut items, &keys);
        let names: Vec<&str> = items
            .iter()
            .map(|v| v.get("name").and_then(|x| x.as_str()).unwrap_or(""))
            .collect();
        assert_eq!(names, vec!["beta", "mu", "alpha", "zeta"]);
    }

    // ─── Phase 3 MED batch: error-propagation tests ───────────────

    // Site 1: collection_url_from_config

    #[test]
    fn collection_url_from_config_absent_returns_ok_none() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        // No config.toml created — absent file must be Ok(None), not Err.
        let result = collection_url_from_config(&app_dir);
        assert!(
            matches!(result, Ok(None)),
            "absent config.toml must return Ok(None), got {result:?}"
        );
    }

    #[test]
    fn collection_url_from_config_corrupt_toml_returns_err() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let path = app_dir.config_toml();
        std::fs::create_dir_all(path.parent().unwrap()).unwrap();
        std::fs::write(&path, b"[hub\ncollection_url = broken{{{{").unwrap();
        let result = collection_url_from_config(&app_dir);
        assert!(
            result.is_err(),
            "corrupt TOML must return Err, got {result:?}"
        );
    }

    #[test]
    fn collection_url_from_config_valid_returns_url() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let path = app_dir.config_toml();
        std::fs::create_dir_all(path.parent().unwrap()).unwrap();
        std::fs::write(
            &path,
            b"[hub]\ncollection_url = \"https://example.com/hub_index.json\"\n",
        )
        .unwrap();
        let result = collection_url_from_config(&app_dir);
        assert_eq!(
            result.unwrap(),
            Some("https://example.com/hub_index.json".to_string())
        );
    }

    #[test]
    fn collection_url_from_config_no_hub_section_returns_none() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let path = app_dir.config_toml();
        std::fs::create_dir_all(path.parent().unwrap()).unwrap();
        std::fs::write(&path, b"[some_other_section]\nfoo = \"bar\"\n").unwrap();
        let result = collection_url_from_config(&app_dir);
        assert!(
            matches!(result, Ok(None)),
            "config without [hub] must return Ok(None), got {result:?}"
        );
    }

    // Site 2: load_cached

    #[test]
    fn load_cached_absent_returns_ok_none() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let result = load_cached(&app_dir, "https://example.com/index.json");
        assert!(
            matches!(result, Ok(None)),
            "absent cache file must return Ok(None), got {result:?}"
        );
    }

    #[test]
    fn load_cached_corrupt_json_within_ttl_returns_err() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let url = "https://example.com/index.json";
        let dir = cache_dir(&app_dir);
        std::fs::create_dir_all(&dir).unwrap();
        let path = dir.join(format!("{}.json", cache_key(url)));
        std::fs::write(&path, b"not valid json {{{{").unwrap();
        // file is freshly written so within TTL
        let result = load_cached(&app_dir, url);
        assert!(
            result.is_err(),
            "corrupt JSON within TTL must return Err, got {result:?}"
        );
    }

    #[test]
    fn load_cached_valid_json_within_ttl_returns_index() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let url = "https://example.com/index.json";
        let dir = cache_dir(&app_dir);
        std::fs::create_dir_all(&dir).unwrap();
        let path = dir.join(format!("{}.json", cache_key(url)));
        let index_json = r#"{"schema_version":"hub_index/v0","updated_at":"2026-01-01T00:00:00Z","packages":[]}"#;
        std::fs::write(&path, index_json).unwrap();
        let result = load_cached(&app_dir, url);
        assert!(
            matches!(result, Ok(Some(_))),
            "valid JSON within TTL must return Ok(Some(_)), got {result:?}"
        );
    }

    /// Helper: backdate a file's mtime by `secs` seconds so it appears stale.
    fn backdate_file(path: &std::path::Path, secs: u64) {
        let past = std::time::SystemTime::now() - std::time::Duration::from_secs(secs);
        let times = std::fs::FileTimes::new()
            .set_accessed(past)
            .set_modified(past);
        let f = std::fs::OpenOptions::new()
            .write(true)
            .open(path)
            .expect("open for backdate");
        f.set_times(times).expect("set_times");
    }

    // L-1: load_cached_full returns Stale (not NotPresent) for outdated cache.
    #[test]
    fn load_cached_full_stale_file_returns_stale_variant() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let url = "https://stale.example.com/index.json";
        // Write a valid cache entry using the helper to get correct serialization.
        write_cache_for_url(&app_dir, url, &make_index(vec![("stale_pkg", "0.1.0")]));
        // Backdate by 2× TTL to ensure it's stale.
        let path = cache_dir(&app_dir).join(format!("{}.json", cache_key(url)));
        backdate_file(&path, CACHE_TTL_SECS * 2);
        let result = load_cached_full(&app_dir, url);
        assert!(
            matches!(result, CacheLookup::Stale(_)),
            "backdated cache must return Stale variant"
        );
    }

    // L-1: aggregate_index with stale cache returns data AND emits warning.
    #[tokio::test]
    async fn aggregate_index_stale_cache_returns_data_and_warning() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir_root = tmp.path().to_path_buf();
        let app_dir = AppDir::new(app_dir_root.clone());
        let url = "https://stale-agg.example.com/index.json";

        // Write a valid cache file with one package.
        write_cache_for_url(&app_dir, url, &make_index(vec![("stale_pkg", "0.1.0")]));
        // Backdate the cache file so it's stale.
        let cache_path = cache_dir(&app_dir).join(format!("{}.json", cache_key(url)));
        backdate_file(&cache_path, CACHE_TTL_SECS * 2);

        // Register the URL in hub_registries.
        let reg_path = app_dir.hub_registries_json();
        std::fs::create_dir_all(reg_path.parent().unwrap()).unwrap();
        let reg_json = serde_json::json!({
            "registries": [{"source": url, "origin": "pkg_install", "added_at": "2026-01-01T00:00:00Z"}]
        });
        std::fs::write(&reg_path, reg_json.to_string()).unwrap();

        let svc = super::super::test_support::make_app_service_at(app_dir_root).await;
        let (index, warnings) = AppService::aggregate_index(&svc).unwrap();

        // Data from stale cache must still be present.
        assert!(
            index.packages.iter().any(|p| p.entity.name == "stale_pkg"),
            "stale package must be included in aggregate, got: {:?}",
            index
                .packages
                .iter()
                .map(|p| &p.entity.name)
                .collect::<Vec<_>>()
        );
        // A stale warning must be emitted.
        assert!(
            warnings
                .iter()
                .any(|w| w.contains("stale") && w.contains(url)),
            "stale cache must emit a warning mentioning the URL, got: {warnings:?}"
        );
    }

    // Site 3: count_evals_for_pkg

    #[test]
    fn count_evals_for_pkg_absent_dir_returns_zero_no_warnings() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let mut warnings: Vec<String> = Vec::new();
        let count = count_evals_for_pkg(&app_dir, "cot", &mut warnings);
        assert_eq!(count, 0, "absent evals dir must return 0");
        assert!(
            warnings.is_empty(),
            "absent evals dir must produce no warnings, got {warnings:?}"
        );
    }

    #[test]
    fn count_evals_for_pkg_corrupt_meta_surfaces_warning() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let evals_dir = app_dir.evals_dir();
        std::fs::create_dir_all(&evals_dir).unwrap();

        // Write a result JSON stub so the file is scanned.
        std::fs::write(evals_dir.join("cot_9999.json"), b"{}").unwrap();
        // Write a corrupt meta.json for the same stem.
        std::fs::write(evals_dir.join("cot_9999.meta.json"), b"not json {{{{").unwrap();

        let mut warnings: Vec<String> = Vec::new();
        let _count = count_evals_for_pkg(&app_dir, "cot", &mut warnings);
        assert!(
            !warnings.is_empty(),
            "corrupt meta.json must produce at least one warning, got {warnings:?}"
        );
        assert!(
            warnings[0].contains("parse"),
            "warning must mention parse: {}",
            warnings[0]
        );
    }

    #[test]
    fn count_evals_for_pkg_valid_meta_counts_correctly() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let evals_dir = app_dir.evals_dir();
        std::fs::create_dir_all(&evals_dir).unwrap();

        // Write a result JSON + valid meta for strategy "cot".
        let meta = r#"{"eval_id":"cot_1","strategy":"cot","timestamp":1}"#;
        std::fs::write(evals_dir.join("cot_1.json"), b"{}").unwrap();
        std::fs::write(evals_dir.join("cot_1.meta.json"), meta).unwrap();

        let mut warnings: Vec<String> = Vec::new();
        let count = count_evals_for_pkg(&app_dir, "cot", &mut warnings);
        assert_eq!(count, 1, "should count 1 valid eval");
        assert!(warnings.is_empty(), "no warnings expected: {warnings:?}");
    }

    // ─── aggregate_index unit tests ───────────────────────────────

    /// Write a minimal HubIndex JSON to the per-source cache for a URL.
    fn write_cache_for_url(app_dir: &AppDir, url: &str, index: &HubIndex) {
        let dir = cache_dir(app_dir);
        std::fs::create_dir_all(&dir).unwrap();
        let path = dir.join(format!("{}.json", cache_key(url)));
        // justification: test helper, panicking on failure is acceptable in tests
        std::fs::write(&path, serde_json::to_string_pretty(index).unwrap()).unwrap();
    }

    fn make_index(packages: Vec<(&str, &str)>) -> HubIndex {
        HubIndex {
            schema_version: "hub_index/v0".into(),
            updated_at: String::new(),
            packages: packages
                .into_iter()
                .map(|(name, version)| IndexEntry {
                    entity: PkgEntity {
                        name: name.to_string(),
                        version: Some(version.to_string()),
                        description: None,
                        category: None,
                        docstring: None,
                    },
                    source: PackageSource::Unknown,
                    card_count: 0,
                    best_card: None,
                })
                .collect(),
        }
    }

    // T1: empty sources → empty index, no warnings
    #[test]
    fn aggregate_index_empty_sources_returns_empty() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        // No registries, no manifest, no seeds in cache → no URLs → empty index.
        // discover_index_urls will still produce AUTO_INSTALL_SOURCES seeds,
        // but their cache files don't exist → Ok(None) for each → empty result.
        let (index, warnings) = {
            // Build a minimal AppService-like test by calling the free functions
            // and replicating the aggregate_index logic directly.
            let mut w: Vec<String> = Vec::new();
            let urls = discover_index_urls(&app_dir, &mut w).unwrap();
            let mut packages: Vec<IndexEntry> = Vec::new();
            let mut seen: std::collections::HashSet<String> = std::collections::HashSet::new();
            for url in &urls {
                if let Ok(Some(idx)) = load_cached(&app_dir, url) {
                    for e in idx.packages {
                        if seen.insert(e.entity.name.clone()) {
                            packages.push(e);
                        }
                    }
                }
            }
            (
                HubIndex {
                    schema_version: "hub_index/v0".into(),
                    updated_at: String::new(),
                    packages,
                },
                w,
            )
        };
        assert!(
            index.packages.is_empty(),
            "no cached sources should produce empty packages"
        );
        assert!(warnings.is_empty(), "no warnings expected for cache misses");
    }

    // T1: one source in cache → packages returned
    #[test]
    fn aggregate_index_one_source_returns_packages() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let url = "https://example.com/test_index.json";
        let source_index = make_index(vec![("cot", "0.1.0"), ("ucb", "0.2.0")]);
        write_cache_for_url(&app_dir, url, &source_index);

        // Register the URL in hub_registries so discover_index_urls finds it.
        let reg_path = app_dir.hub_registries_json();
        std::fs::create_dir_all(reg_path.parent().unwrap()).unwrap();
        let reg_json = serde_json::json!({
            "registries": [{"source": url, "origin": "pkg_install", "added_at": "2026-01-01T00:00:00Z"}]
        });
        std::fs::write(&reg_path, reg_json.to_string()).unwrap();

        let mut warnings: Vec<String> = Vec::new();
        let urls = discover_index_urls(&app_dir, &mut warnings).unwrap();
        let mut packages: Vec<IndexEntry> = Vec::new();
        let mut seen: std::collections::HashSet<String> = std::collections::HashSet::new();
        for u in &urls {
            if let Ok(Some(idx)) = load_cached(&app_dir, u) {
                for e in idx.packages {
                    if seen.insert(e.entity.name.clone()) {
                        packages.push(e);
                    }
                }
            }
        }

        assert!(
            packages.iter().any(|p| p.entity.name == "cot"),
            "cot expected"
        );
        assert!(
            packages.iter().any(|p| p.entity.name == "ucb"),
            "ucb expected"
        );
    }

    // T2: duplicate package across two sources → first source wins
    #[test]
    fn aggregate_index_deduplicate_by_name_first_wins() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let url_a = "https://a.example.com/index.json";
        let url_b = "https://b.example.com/index.json";

        // Both sources have "cot" but different versions.
        let idx_a = make_index(vec![("cot", "1.0.0")]);
        let idx_b = make_index(vec![("cot", "2.0.0"), ("ucb", "0.1.0")]);
        write_cache_for_url(&app_dir, url_a, &idx_a);
        write_cache_for_url(&app_dir, url_b, &idx_b);

        let reg_path = app_dir.hub_registries_json();
        std::fs::create_dir_all(reg_path.parent().unwrap()).unwrap();
        let reg_json = serde_json::json!({
            "registries": [
                {"source": url_a, "origin": "pkg_install", "added_at": "2026-01-01T00:00:00Z"},
                {"source": url_b, "origin": "pkg_install", "added_at": "2026-01-01T00:00:00Z"}
            ]
        });
        std::fs::write(&reg_path, reg_json.to_string()).unwrap();

        let mut warnings: Vec<String> = Vec::new();
        let urls = {
            let mut raw = discover_index_urls(&app_dir, &mut warnings).unwrap();
            // Restrict to only our two test URLs so seed URLs don't interfere.
            raw.retain(|u| u == url_a || u == url_b);
            raw
        };

        let mut packages: Vec<IndexEntry> = Vec::new();
        let mut seen: std::collections::HashSet<String> = std::collections::HashSet::new();
        for u in &urls {
            if let Ok(Some(idx)) = load_cached(&app_dir, u) {
                for e in idx.packages {
                    if seen.insert(e.entity.name.clone()) {
                        packages.push(e);
                    }
                }
            }
        }

        let cot_count = packages.iter().filter(|p| p.entity.name == "cot").count();
        assert_eq!(cot_count, 1, "dedup: cot must appear exactly once");
        let ucb_count = packages.iter().filter(|p| p.entity.name == "ucb").count();
        assert_eq!(ucb_count, 1, "ucb from second source must appear");
    }

    // T3: corrupt cache file → warning collected, other sources unaffected
    #[test]
    fn aggregate_index_corrupt_cache_collects_warning() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir = AppDir::new(tmp.path().to_path_buf());
        let url_corrupt = "https://corrupt.example.com/index.json";

        // Write corrupt JSON to the cache slot.
        let dir = cache_dir(&app_dir);
        std::fs::create_dir_all(&dir).unwrap();
        let path = dir.join(format!("{}.json", cache_key(url_corrupt)));
        std::fs::write(&path, b"{{{{ not valid json").unwrap();

        let reg_path = app_dir.hub_registries_json();
        std::fs::create_dir_all(reg_path.parent().unwrap()).unwrap();
        let reg_json = serde_json::json!({
            "registries": [{"source": url_corrupt, "origin": "pkg_install", "added_at": "2026-01-01T00:00:00Z"}]
        });
        std::fs::write(&reg_path, reg_json.to_string()).unwrap();

        let mut warnings: Vec<String> = Vec::new();
        let urls = discover_index_urls(&app_dir, &mut warnings).unwrap();
        let mut packages: Vec<IndexEntry> = Vec::new();
        let mut seen: std::collections::HashSet<String> = std::collections::HashSet::new();
        let mut extra_warnings: Vec<String> = Vec::new();
        for u in &urls {
            match load_cached(&app_dir, u) {
                Ok(Some(idx)) => {
                    for e in idx.packages {
                        if seen.insert(e.entity.name.clone()) {
                            packages.push(e);
                        }
                    }
                }
                Ok(None) => {}
                Err(e) => extra_warnings.push(format!("hub cache read failed for {u}: {e}")),
            }
        }

        assert!(
            !extra_warnings.is_empty(),
            "corrupt cache must produce a warning"
        );
        assert!(
            extra_warnings[0].contains("hub cache read failed"),
            "warning text mismatch: {}",
            extra_warnings[0]
        );
        assert!(packages.is_empty(), "no packages from corrupt source");
    }

    // M-2: registry-load failure is demoted to a warning; accumulated
    // warnings before the failure are preserved in the returned vec.
    #[tokio::test]
    async fn aggregate_index_registry_failure_returns_ok_with_warning() {
        let tmp = tempfile::tempdir().unwrap();
        let app_dir_root = tmp.path().to_path_buf();

        // Write corrupt hub_registries.json so load_registries fails.
        let reg_path = AppDir::new(app_dir_root.clone()).hub_registries_json();
        std::fs::create_dir_all(reg_path.parent().unwrap()).unwrap();
        std::fs::write(&reg_path, b"{{{{ not valid json").unwrap();

        // Also write a corrupt config.toml to generate a pre-registry warning.
        // (config.toml hub.collection_url parse warns before the registry step.)
        // We skip this to keep the test minimal — just verify registry failure
        // demotes to warning and result is Ok.

        let svc = super::super::test_support::make_app_service_at(app_dir_root).await;
        let result = AppService::aggregate_index(&svc);
        assert!(
            result.is_ok(),
            "aggregate_index must return Ok even on registry-load failure, got: {result:?}"
        );
        let (index, warnings) = result.unwrap();
        assert!(
            index.packages.is_empty(),
            "degraded response must have empty packages"
        );
        assert!(
            !warnings.is_empty(),
            "registry-load failure must produce a warning"
        );
        assert!(
            warnings
                .iter()
                .any(|w| w.contains("hub registry discovery failed")),
            "warning must mention registry discovery failure, got: {warnings:?}"
        );
    }
}