Indexer service pipeline

The indexer service watches the monitor table and searches torrent indexers for pending episodes and seasons. When it finds a match it inserts a download queue entry for the downloader service to pick up.

Startup

1. Database connection initialised (same PostgreSQL as core).
2. Provider packages self-register via init() (kbdex and Prowlarr are blank-imported in cmd/indexer/main.go).
3. PollAndQueue starts in a background goroutine.
4. Health/test HTTP server starts on port 8082.

Poll loop

Runs every prowlarrInterval seconds (default 10 s).

Timer fires
      │
      ▼
Query DB for one pending monitor
  WHERE monitored = true
    AND available = false
    AND (status = 'pending'
         OR status = 'searching' for > 10 min)
  ORDER BY is_season DESC  ← season packs searched first
      │
      ▼
Mark monitor status = 'searching'
      │
      ▼
Build SearchRequest {title, alternate_titles, season, episode, library_id, ...}
      │
      ▼
GetEnabled(db) → active providers (each enabled via its kbdexEnabled / prowlarrEnabled toggle; results from all are merged)
      │
      ▼
Provider.Search(ctx, db, req)   [see provider detail below]
      │
      ▼
buildMatchLog  →  filter by title similarity + season + episode
      │
      ▼
pickBest  →  quality rank + seeders sort, blacklist check
      │
      ├── match found → insert download_queue row, set monitor status = 'queued'
      └── no match    → set monitor status = 'pending' (retry next cycle)

Provider: kbdex

kbdex is an AniDB-aware search service. It handles title resolution and episode filtering server-side.

SearchRequest
      │
      ▼
lookupAnidbID: SELECT source_id FROM media WHERE id = library_id
      │
      ▼
GET {kbdexUrl}/search?anidb_id=N[&season=S][&episode=E]
      │  Results cached on disk keyed by "kbdex:{id}:s{S}:e{E}"
      │  Cache TTL = prowlarrCacheAge
      ▼
[]TorrentResult  (already filtered by kbdex server-side via anitopy)

Provider: Prowlarr

Prowlarr is a generic indexer aggregator. kbarr queries it with multiple title variants and merges results.

SearchRequest
      │
      ▼
Build query variants from title + alternate titles
  ├── Season searches: "Title S01", "Title Season 1", "Title Batch", ...
  └── Episode searches: "Title S01E05", "Title - 05", ...
      │
      ▼
For each variant: GET {prowlarrUrl}/api/v1/search?query=...&apikey=...
      │  Each variant result set cached on disk (prowlarrCacheAge TTL)
      ▼
Merge + deduplicate by DownloadURL
      │
      ▼
[]TorrentResult

Client-side filtering (shared by both providers)

After the provider returns results, buildMatchLog and pickBest apply a second pass:

buildMatchLog — runs each torrent filename through anitogo (Go torrent filename parser), then checks:

1. Title similarity ≥ matchThreshold (default 80%) using Sørensen–Dice bigrams
2. Parsed season matches the monitor's season
3. For season packs: rejects individual episode releases
4. For episodes: parsed episode matches exactly

pickBest — from passing results:

1. Removes blacklisted torrents
2. Drops results above the preferredQuality cap (e.g. drops 4K if preference is 1080p)
3. Sorts by quality rank, subtitle language, release-group preference, and seeder count (order depends on releaseGroupPriorityMode)
4. Returns the top entry

Release group preference ranking

Two settings control release-group-based ordering:

Setting	Type	Default	Description
releaseGroupPreferenceOrder	comma-separated string	All 11 canonical groups	Ordered list of preferred release groups. First = most preferred. Anime Time is accepted as an alias for ASW.
releaseGroupPriorityMode	enum	tie-break	How strongly the group preference is applied.

Tie-break mode (default): Compares the configured group order only when quality rank and subtitle language are equal, acting as a tiebreaker before seeders. Releases from preferred groups are favoured but do not outrank a higher-quality release or one with a matching subtitle.

Strong mode: Compares the configured group order immediately after the quality-cap gate, before quality rank itself. A preferred-group release can outrank a higher-quality release from a non-preferred group. The quality cap still applies (e.g. 4K excluded if preference is 1080p).

Fallback: When no candidate matches any configured group or the preference list is empty, the existing quality → subtitle → seeders ordering applies unchanged. Unknown or missing release groups sit after all preferred groups.

Key packages

Package	Role
internal/indexer/provider/	Provider interface, registry, shared cache utilities
internal/indexer/provider/kbdex/	kbdex provider implementation
internal/indexer/provider/prowlarr/	Prowlarr provider implementation
internal/indexer/service/	Poll loop, match scoring, download queue insertion
internal/parser/	anitogo wrapper with memoisation and Japanese episode fallbacks