# arr — design One service that replaces Radarr and Sonarr, and later Bazarr, for a single household. Rust workspace, API-first, SQLite, no authentication layer. This document is the contract. Issues reference it by section rather than restating it. --- ## 1. Why Five .NET services idle at 600-900 MB to do a job with one loop in it: decide what you want, find it, fetch it, put it somewhere Jellyfin can read. Each has a configuration surface an order of magnitude larger than the subset actually used, and none of them share a model, so the same show is configured three times in three dialects. The replacement targets 20-40 MB resident, one binary, one database, one policy language. This is not a general-purpose Radarr replacement. Every decision below is allowed to be narrow. ## 2. Non-goals Explicitly out of scope, permanently unless stated: - **Authentication.** The perimeter is a VPN plus Authelia at the proxy. The service binds without auth, same trust model as the existing Transmission RPC. - **Library migration or filesystem scan.** The service knows only what it put on disk. Adopting the pre-existing library, if ever wanted, is a one-off script against both APIs, not a feature. - **Automatic quality upgrades.** See §5.4. - **Multiple quality profiles.** Policy attaches to a root folder. See §5.1. - **Trakt.** Jellyfin and Stremio already write watch state there and nothing in this pipeline reads it. - **Calendar view, actor/director following, per-indexer UIs.** Prowlarr owns indexer configuration and keeps doing so. - **Books and music.** `shelfmark` and `calibre-web-automated` already cover books. If they ever land here they reuse maybe three of the ten crates, so nothing is generalised in advance. See §11. ## 3. System context ``` ┌──────────────┐ TMDB ──────▶│ │ │ arr │────▶ Transmission RPC 10.6.10.45:9091 Prowlarr ──────▶│ │ (Torznab) │ (this) │────▶ ffprobe local subprocess │ │ Jellyseerr ─────▶│ │────▶ Jellyfin refresh 10.6.10.18:8096 (Radarr-compat) └──────┬───────┘ │ ntfy per-person topics ▼ SQLite + media tree on /mnt/media ``` Everything already exists except `arr`. Prowlarr keeps owning tracker auth, Cloudflare bypass via FlareSolverr, rate limiting and the Cardigann definitions — replacing it buys nothing. Transmission runs natively in its own LXC (VMID 130, `10.6.10.45`), RPC unauthenticated, download dir `/mnt/media/transmission/complete`. ## 4. Domain model Movies and series are separate aggregates. They share machinery, not a table. ``` Root id, kind (movie|tv), audience (main|kids), path, policy_id Policy id, name required_audio rule set, see §5.2 dub_blacklist [pt-BR] hdr_rules see §5.3 size_bands per resolution: floor, target, penalty curve resolution_pref [2160p, 1080p] source_weights small tiebreaker Movie id, tmdb_id, title, year, original_language, root_id wanted (bool), overrides (json), state, blocked (bool) search_attempts, last_searched_at Series id, tmdb_id, title, year, original_language, root_id auto_track (bool), overrides (json), blocked (bool) Season id, series_id, number, tracked (bool) Episode id, season_id, number, title, air_date wanted (bool), state search_attempts, last_searched_at MediaFile id, owner_kind (movie|episode), owner_id, path, size probed (json: resolution, source, hdr, audio_tracks, sub_tracks) waiver (json|null) which rule was relaxed to allow this import Release id, indexer_id, guid, name, size, seeders, publish_date, download_url parsed (json) what the name claims score, verdict eligible | waived | rejected(rule) Grab id, release_id, target_kind, target_id, infohash state, grabbed_at, imported_at Blacklist infohash, normalised_name, reason, created_at Owner id, name, ntfy_topic TitleOwner title_kind, title_id, owner_id many-to-many ``` ### 4.1 Intent lives at the leaf Sonarr's `monitored` conflates "do I want this show" with "is anything happening right now". It is user-maintained, so it drifts and stops meaning anything. Here, intent is `Episode.wanted` and `Movie.wanted` only. `Series.auto_track` is not intent — it is a rule that says "when metadata reveals a new season, mark its episodes wanted". An untracked series where you manually marked S02 needs no special case: three wanted episodes, nothing else. ### 4.2 Status is derived, never stored as intent Recomputed on metadata refresh and on file change: | Status | Condition | |---|---| | `airing` | an episode aired or airs within ±14 days | | `incomplete` | wanted episodes missing, nothing currently airing | | `waiting` | season finished, next unannounced or future-dated | | `complete` | everything wanted is on disk | | `ended` | series finished upstream and complete | Default list view shows `airing` and `incomplete`. Everything else collapses behind one toggle. A one-off season grab therefore disappears from the default view by itself once satisfied, and a tracked show reappears by itself when a new season is announced. Nothing to remember to flip. ### 4.3 People are tags, not paths `Owner` is a many-to-many tag on titles. It drives UI filtering, the default list, and notification routing. It never appears in a path. A file lives in one place; audiences overlap. ## 5. Policy engine The core of the app and the part worth testing hardest. Lives in `arr-core`, pure, no IO. ### 5.1 Policy attaches to a root Two roots per media kind (`main`, `kids`), each with one policy. Jellyseerr's "pick a quality profile per request" model is satisfied by exposing exactly one fake profile per root and ignoring whatever it sends. Per-title `overrides` relax the root policy for one title. Same mechanism in both directions — `only_4k` tightens, `allow_english_audio` loosens. ### 5.2 Language Requires a concept the release name does not carry: the **original language of the title**, from TMDB, distinct from a track's language. ``` reject audio track T if T.lang ∈ dub_blacklist and T.lang ≠ title.original_language ``` `dub_blacklist = [pt-BR]` globally. That single expression covers both roots: - **main** — require a track matching `original_language`. Others may ride along. A Brazilian film has `original_language = pt-BR`, so its own soundtrack passes; a pt-BR dub of an English film does not. - **kids** — require pt-PT, or `original_language` when that is already Portuguese. pt-BR never satisfies the requirement, because the child does not read and a Brazilian dub is not what he should be watching. - **subtitles** — no blacklist. pt-BR subtitles are always fine. **The pt-PT / pt-BR detection problem.** ISO-639-2 has one code, `por`, for both. `ffprobe` reports `por` either way. Three signals in order: 1. Release name markers — Brazilian releases self-identify loudly: `PT-BR`, `Dublado`, `Nacional`, `Dual Áudio`. 2. `ffprobe` stream *title* and `handler_name` strings, not the language code — often literally `Portuguese (Brazil)`. 3. Container-level BCP-47 tags where present (Matroska can carry `pt-BR`). When none resolve it, tag the track `por-unverified` and surface it. Do not guess. Guessing toward `kids` gives a child a Brazilian dub; guessing toward `main` rejects a Brazilian film's own audio. **Sourcing consequence for `kids`.** European Portuguese dubs live almost entirely in streaming WEB-DLs (Disney+, Netflix, Max) and essentially never in BluRay encodes or remuxes. That root biases hard toward WEB-DL sources, and unlike audio in general it *is* often pre-grab visible, since multi-audio releases advertise themselves (`MULTi`, `DUAL`, explicit language lists). When nothing qualifies, the title sits in a visible **no-PT-source queue** rather than being grabbed in English. That queue is acted on manually, sometimes for months. A per-title `allow_english_audio` override empties one item from it with one click, and the resulting file is recorded with a `waiver` so the UI shows it as "English, no dub" rather than a clean match. ### 5.3 HDR and Dolby Vision The naive rule "blacklist Dolby Vision" is wrong and would discard a large share of good 4K releases. | Profile | Base layer | Behaviour without DV support | Verdict | |---|---|---|---| | 5 | none (ICtCp) | green/purple, unwatchable | **reject** | | 7 | dual-layer BL+EL | depends on player, unreliable | **reject** | | 8.1 | HDR10 | plays as HDR10 | **accept** | The existing library is already almost entirely Profile 8.1 with no Profile 5, and Jellyfin tonemaps it correctly on the current GPU path. Profile is knowable only from `ffprobe`, never from a release name. A `DV` chip in search results means "the name claims DV" and its absence means nothing. ### 5.4 Quality, and why there is no upgrade loop Default: take 4K if it exists now, otherwise 1080p. Per-title `only_4k` rejects 1080p outright and keeps searching indefinitely — the escape hatch for the handful of titles worth waiting on. **No grab delay.** Deliberately rejected. Radarr's delay profile exists to stop first-match-wins from always yielding 1080p; here the `only_4k` flag solves the same problem upfront and without making every grab slower. **No automatic upgrade loop.** An automatic upgrade re-downloads 40-80 GB and restarts a seeding obligation for something already watched. `needs_upgrade` is a marker in the UI and a manual "search again" button, not a background job. ### 5.5 Scoring: distance from a target size Source tier is **not** the dominant term. A remux should win only when nothing smaller exists. Per resolution, a floor, a target and a growing penalty above target. For 4K: floor ~8 GB, target ~22 GB. A 20 GB WEB-DL sits at target and wins; a 60 GB remux scores badly but stays eligible, so it is picked when it is the only option. The floor matters — unbounded "smaller is better" selects a 3 GB 4K encode that looks like mud. Source tier (`Remux > BluRay > WEB-DL > WEBRip > HDTV`) survives as a small tiebreaker. Seeders are log-scaled and small: enough to complete, past that it does not matter. Telesync, CAM and screener are **hard filters**, not low scores. Exact numbers are policy rows, tuned by hand. The model is the decision. ### 5.6 Two phases of truth Release names lie or omit. Files do not. - **Pre-grab** — parse the name. It is all there is. Use it for hard filters (source type, resolution, explicit language markers) and for scoring. - **Post-download** — `ffprobe` before import. Real audio languages, real HDR format and DV profile, real codec, real duration. Store both, `parsed` on the release and `probed` on the file. The gap between them is also data: it tells you which release groups mislabel. ### 5.7 Hard fail versus soft fail A policy violation found by `ffprobe` is not one thing. - **Hard fail** — useless. No original-language audio track at all, DV Profile 5, wrong title, corrupt. Do not import, blacklist the release, grab the next candidate. - **Soft fail** — watchable but not what was asked. 1080p while `only_4k` was set, PT audio missing on a `kids` title. Import it, record a `waiver`, surface it. Neither deletes the torrent. See §7.3. ## 6. Sourcing ### 6.1 Prowlarr, per-indexer Torznab `GET /api/v1/indexer` enumerates. Each indexer is then addressed at its own Torznab endpoint: ``` GET /{indexerId}/api?apikey=…&t=caps GET /{indexerId}/api?apikey=…&t=search&q=… GET /{indexerId}/api?apikey=…&t=movie&imdbid=… GET /{indexerId}/api?apikey=…&t=tvsearch&tvdbid=…&season=&ep= ``` Prowlarr's aggregate `/api/v1/search` is deliberately not used: Torznab is the stable standard rather than an internal UI API, it gives real RSS semantics, and per-indexer addressing keeps indexer identity in hand — which the per-tracker seeding rules need anyway. `t=caps` per indexer records which search modes each tracker supports. Not all do ID-based search; some are text-only. ### 6.2 Three triggers, three cost profiles | Trigger | Cost | Cadence | |---|---|---| | RSS sync | one call per *indexer*, independent of library size | ~10 min, never backs off | | Targeted search | one call per *wanted item* per attempt | exponential backoff | | Manual | one call, user-initiated | on demand | RSS is an empty-query Torznab call whose results are matched against the wanted list locally. Because its cost does not scale with the wanted list, every wanted item is matched against every RSS result forever. Targeted search backs off `1h → 6h → 1d → 3d`, capped at 7d, reset when the title's metadata changes. It never gives up entirely, it goes quiet. **Do not search before the release exists.** TMDB carries release dates; a movie with no digital release date gets zero targeted searches. This is the single largest source of wasted queries in Radarr and it is free to avoid. ### 6.3 Blacklist Keyed on infohash and normalised release name. Anything that hard-failed post-`ffprobe` is never grabbed again, including by RSS. A manual `blocked` flag stops targeted search for a title entirely while leaving RSS matching on. ## 7. Download and import ### 7.1 Transmission RPC at `10.6.10.45:9091`, no credentials. Labels are `movies-main`, `tv-kids` and so on — enough to find things in Transmission's own UI, and distinct from Radarr's existing `radarr`/`sonarr` labels so both stacks can run side by side. ### 7.2 Hardlink Verified: Radarr's only media bind is `/mnt/media-v2:/mnt/media`, one mount, one dataset, and the existing arrs hardlink-import today. So `link()` succeeds. Implementation still falls back to copy on `EXDEV` rather than trusting that forever — no configuration flag, no way to get it wrong. Hardlinking gives the library file and the seeding file independent names at zero extra disk. Copy would double storage for the entire seeding window, which at 4K is 40-80 GB per title. ### 7.3 Two lifecycles, deliberately decoupled The torrent and the library entry are separate state machines. Seeding obligation is **per tracker**, configured locally because Prowlarr does not expose tracker rules — `ratio` and `min_seed_time`. Set `seedRatioLimit` and `seedIdleLimit` on the torrent at add time and let Transmission enforce them. A reaper deletes torrents Transmission reports as done seeding. Consequently a hard-failed release is blacklisted and never imported, but its torrent keeps seeding until the obligation clears. Nothing is deleted early to satisfy the library. ### 7.4 Layout ``` /mnt/media/movies/main/Dune Part Two (2024) [tmdbid-693134]/ Dune Part Two (2024) [tmdbid-693134] - [2160p][WEB-DL][HDR10].mkv /mnt/media/tv/kids/Bluey (2018) [tmdbid-82728]/ Season 01/ Bluey (2018) - S01E02 - Hospital [1080p][WEB-DL][pt-PT].mkv ``` Media kind first, hard audience boundary second, people nowhere. - **Provider ID in the folder name** turns Jellyfin matching from fuzzy string guessing into exact lookup. - **Attribute tags come from `ffprobe`**, not from the release name, so they are true. The filename doubles as an audit surface: `ls` shows which files are DV or which of the kids' files are still English-only, with the app stopped. - **One folder per title even for a single file**, so sidecar subtitles and artwork stay contained and deletes are atomic. - **Release group is deliberately absent.** It is not a selection criterion and it makes filenames long enough to break a terminal. During transition, write into the existing roots so Jellyfin needs no reconfiguration and new content appears immediately. Radarr will not touch a folder it has no record of. ### 7.5 Jellyfin On successful import, call Jellyfin's refresh endpoint for the affected library. Its filesystem watcher misses things. One HTTP call at the end of import. ## 8. The reconcile loop There is no job queue. The database rows are the work list. A wanted episode with no file is a pending grab. A torrent past its seeding rule is a pending delete. A downloaded file not yet probed is a pending import. Every tick, compare desired state to actual state and act on the gap. This is idempotent and crash-safe by construction. Kill the process mid-grab and the next tick recomputes the same gap and continues. A job table would need retry counts, dead-lettering and reconciliation against Transmission anyway, because Transmission is an external system that changes underneath the app. Transient state — a search in flight, download progress — is in memory and rebuilt from Transmission on startup. Ticks are staggered: reconcile every 30 s, RSS every 10 min, metadata refresh daily, reaper every 5 min. ## 9. API and UI ### 9.1 API-first The HTTP API is the product surface; the web UI is a client of it with no privileged path. OpenAPI spec generated from handler annotations, served alongside the app, and used to generate the TypeScript client. Own schema first. Radarr-compatible endpoints are a **later, separate, lower-priority crate** (§9.4), not the primary shape. ### 9.2 Unified search One box. Two grouped result sets: **in library** first (title match, and for TV also episode title, so `bluey hospital` finds the episode), **on TMDB** below. Enter on a TMDB result opens the add flow with root and policy pre-filled. The same box accepts a raw TMDB or IMDb ID, and a pasted magnet or `.torrent`, which skips to the manual-grab flow. There is never a moment where the user has to know whether they are searching or adding. ### 9.3 Manual search results Radarr's manual search is unusable because the raw release name is the dominant column, pushing everything that actually decides the choice off-screen. Invert it. The policy engine has already classified every candidate: - **Three buckets.** `eligible` shown by default, sorted by score. `waived` (fails a soft rule, grabbable with one click that writes an override) and `rejected` collapse to a count, expandable. - **Columns are parsed attributes as chips** — score, resolution, source, HDR, audio languages, size, seeders. Fixed width, no horizontal scroll. - **Release name is secondary**, truncated, full string on expand. It is evidence for when you disagree with the parse, not the primary key. - **Every rejected row names the rule that killed it**, so over-strict filters are visible without reading names. Pre-grab, HDR and audio chips are best-effort from the name (§5.6). ### 9.4 Jellyseerr compatibility Jellyseerr stays. It already does Jellyfin user auth, discovery and request approval — none of which is the problem being solved, and rebuilding it doubles the project. A thin `arr-compat` crate exposes the slice Jellyseerr actually calls: ``` GET /api/v3/system/status GET /api/v3/rootfolder → the real roots GET /api/v3/qualityprofile → one fake profile per root GET /api/v3/tag GET /api/v3/movie existence check POST /api/v3/movie add GET /api/v3/movie/lookup ``` plus the `series` equivalents. Thin mappings onto the real domain, isolated in one crate that never leaks into `arr-core`. Lower priority than everything in §5-8. ### 9.5 Notifications `ntfy`, one topic per `Owner`. Three events only — Radarr's failure mode is notifying on everything and being muted within a week. - **Imported** → to the title's owners. The only good-news notification. - **Needs a decision** → to the operator alone. Entered the no-PT-source queue, or hard-failed twice on different releases. - **Broken** → to the operator alone. Prowlarr, Transmission or TMDB unreachable, disk full. Not notified: grabs, searches, downloads starting or finishing, soft fails. ## 10. Persistence SQLite via `sqlx`, compile-time-checked queries, migrations in `arr-db`. A few thousand rows, single writer. Postgres would buy nothing and cost a service. Policy lives in the database, not a config file — size targets and DV rules get tuned by hand during testing and a restart-to-reload loop gets old immediately. Only bootstrap settings (bind address, Prowlarr URL, Transmission URL, TMDB key, media root) come from config/env. Backup is `sqlite3 .backup` on a timer. ## 11. Crate layout Cargo workspace, `members = ["crates/*"]`, versions pinned once in `[workspace.dependencies]`, following `~/tea/maestro`. ``` arr-core domain types, policy engine, scoring no IO, no heavy deps arr-parse release name parsing no IO arr-meta TMDB client arr-indexer Torznab via Prowlarr arr-dl Transmission RPC arr-probe ffprobe wrapper arr-db sqlx + migrations arr-api axum + OpenAPI arr-compat Radarr/Sonarr v3 shim for Jellyseerr arr-daemon reconcile loop, wires everything arr-e2e cross-process integration tests web/ Vite + TypeScript SPA, embedded via include_dir ``` The rule: `arr-core` and `arr-parse` hold the logic worth testing constantly and must not depend on axum, sqlx or reqwest. Everything expensive is downstream of them. Nothing is generic over media kind. Movies are built concretely, then TV concretely, and shared machinery is extracted only once both exist. An abstraction derived from one example fits one example. ## 12. CI Lints declared once in the root manifest: ```toml [workspace.lints.rust] unused_crate_dependencies = "warn" missing_debug_implementations = "warn" [workspace.lints.clippy] pedantic = { level = "warn", priority = -1 } unwrap_used = "warn" ``` Member crates carry only `[lints] workspace = true`. **Per-push gate**, target under 5 minutes: | Step | Tool | |---|---| | format | `cargo fmt --check` | | lint | `cargo clippy --all-targets -- -D warnings` | | unused deps | `cargo machete` (stable; `cargo udeps` needs nightly and a full rebuild) | | test | `cargo nextest run` | | frontend | `biome ci web/` and `tsc -b --noEmit` | **Off the gate**, scheduled: `cargo deny` for advisories and licenses. Coverage, if ever, likewise. Neither blocks a push. Total wall-clock on the self-hosted Gitea runner is an explicit constraint. The lever is caching, not step selection: cache `~/.cargo/registry`, `~/.cargo/git` and `target/`, keyed on `Cargo.lock` plus `rust-toolchain.toml`. Never build `--release` in the gate. **End-to-end tests, only at the seams that actually break:** - Prowlarr and TMDB — `wiremock` with recorded real responses as fixtures. Never live: trackers rate-limit, and it would leak credentials into CI. - Transmission — a real container as a CI service. RPC semantics are the most likely source of surprise and it starts in a second. - `ffprobe` — tiny committed clips, a few KB each. The Jellyfin LXC already has the right fixtures at `/srv/jellyfin-test`, including a real **DV Profile 5** clip. That is the test proving the policy engine rejects Profile 5 and accepts 8.1 — the subtlest rule in the system. E2E runs on `main` and on pull requests touching those crates, not every push. ## 13. Build order Each phase ends at something usable end to end. No phase is a refactor of the previous one. 1. **Skeleton** — workspace, CI gate, config, SQLite migrations, health endpoint, embedded empty SPA. 2. **Parse and score** — `arr-parse` and `arr-core` against fixture release names. Pure, fast, heavily tested. No network. 3. **Read-only sourcing** — TMDB lookup, Prowlarr enumeration and search, classified results over the API. Still grabs nothing. 4. **Movies, end to end** — add a movie, grab, download, `ffprobe`, hardlink, rename, Jellyfin refresh, seeding reaper. The first real cutover test is one movie Radarr does not know about. 5. **UI** — unified search, manual search buckets, library views, the queues. 6. **TV** — seasons, episodes, `auto_track`, per-episode versus season-pack grabbing, derived status. 7. **Owners and notifications** — tags, per-person ntfy topics, filtered views. 8. **Jellyseerr compat** — `arr-compat`. 9. **Subtitles** — replaces Bazarr. Out of scope for this document. Movies before TV because TV adds season packs, air-date calendars and per-episode state on top of an otherwise identical pipeline. Doing it second means that pipeline is already proven. ## 14. Open questions - **Remux playback.** Whether a 4K remux streams cleanly to the Shield is untested. The usual failure is audio, not bitrate: BluRay remuxes carry TrueHD/DTS-HD MA, and if the Shield cannot bitstream that downstream, Jellyfin transcodes audio and playback stutters while video direct-plays. Test before fixing the 4K size ceiling in §5.5. The outcome changes the conclusion from "remuxes are bad" to "remux audio needs a downmix". - **Size band numbers** in §5.5 are placeholders pending that test. - **Season-pack re-grab.** When an airing season completes, the episodes are already present individually. Nothing re-grabs the pack. Whether that is ever wanted is unresolved and deliberately deferred.