Files
siftlode/backend/app
peter 3b0e365e26 refactor(plex): the browse, detail, people and collection pages read through queries and write through the service
The HTTP files browse, detail, people, collections and _shared do no database work of their own
now. New plex/queries.py (the rows a page shows, a user's watch state through userscope),
plex/service.py (the info pages' enrichment, a collection's editable flag, the row kept after a
failed follow-up read, the person bio's background fetch; none commits), plex/library.py (the
unified browse feed, its search and facets) and plex/collections.py (a collection's source,
editability, card, certificate and member order). Every watch-state join in the moved code names
its owner through owned_by.

Pins 354 -> 178 in 4 files; basedpyright baseline 132 -> 118.
2026-10-19 22:11:20 +02:00
..
2026-06-14 04:40:22 +02:00

Backend conventions

The rules below are already followed across backend/app — they lived only in a few module docstrings (userscope.py, routes/_common.py) until this file collected them (E3 S3, B-core-20). When you add code, match these so the next reader doesn't have to guess "which pattern do I copy".

Module layering

Three layers, by who runs the code — not by feature:

  1. routes/… — request-only. A route module holds HTTP concerns: auth dependencies, request/ response models, status-code mapping, serialization. It owns logic that runs only on a request. Business logic that a request happens to trigger does not live here if anything else runs it too.

  2. plex/, downloads/, sync/, issues/ — domain logic shared by more than one caller. Anything the scheduler or the worker runs (not just a request) lives in one of these domain packages, so the route, the worker, and the scheduler share one definition. Examples from this codebase: downloads/service.py owns enqueue + the job state transitions (routes call it); plex/sync.py is run by both the admin route and the scheduler; downloads/pipeline.py is the worker's child pipeline; issues/bundle.py is the one definition of a bug report's files, for the zip export and the tracker.

  3. Flat app/*.py core modules — cross-cutting primitives. auth (with apitokens, a machine's folder-scoped way into the Files library), sysconfig, quota, audit, jobruns (every background run's durable row, its words in runstatus), notifications, userscope, ratelimit, progress, logs (the one logging configuration), logsink (its log_events table), diagnostics (a user's consented log level), debugsession (a recording that tags its user's lines, E16) and collation (A→Z in the reader's alphabet, E30), … are single-file primitives many layers import. They depend on nothing above them (a core module must never import a routes/… module).

Extraction trigger: the SECOND consumer. Keep new logic inline in its first caller. The moment a second caller needs it (a worker as well as a route; a scheduler as well as a route), extract it down a layer — into the relevant domain package, or a flat core module if it's cross-cutting. Don't pre-abstract for a single caller; don't leave shared logic duplicated once there are two.

Transaction ownership

This follows CLAUDE.md's canonical rule verbatim — "the handler/job-wrapper commits; helpers flush (only quota and jobruns own their session)" — so read it that way, not as an exception to it. The commit belongs to the operation owner; anything called inside another transaction only stages its change (db.add / flush) and lets the owner commit, so the whole operation is one transaction. audit.record() is the reference: it adds the audit row and the caller commits it together with the mutation it records, so an audit entry can never exist without its change (or vice-versa).

  • The operation owner is usually the route handler. A service.* operation the handler delegates a whole transition to (e.g. service.cancel) is that owner and commits its one transition — it isn't a mid-operation helper. A helper that owns its OWN short-lived session (the worker's jobdb writes, jobruns' run rows — the same carve-out CLAUDE.md grants quota) commits that session. Everything else flushes.
  • SessionLocal is expire_on_commit=False: after a raw UPDATE + commit, an ORM object you already loaded is stale. Read the fresh value from the row (RETURNING, or a re-SELECT), not the ORM attribute — see service.decr_ref_count.

Shared counters and status: do it atomically at the DB

  • Never read-modify-write a shared counter in Python (x.count = x.count + 1). Concurrent sessions lose an update. Use a DB-atomic statement — col = col + 1, or greatest(col - 1, 0) with RETURNING so the caller branches on the post-value under the row lock (service.incr_ref_count / decr_ref_count).
  • Download job status is a JobStatus StrEnum (downloads/status.py), not bare strings. The HOLDING set defines which states hold a MediaAsset (so release accounting stays correct); STOPPED_BY_ROUTE is the route-initiated stop set. A worker child's terminal write goes through service.finalize_if_running (an atomic UPDATE … WHERE status='running') so a finishing child can't resurrect a job a route just stopped.

Config: one home per kind

  • app.config.settings — boot/env config (DB URL, download root, worker concurrency): read once at startup, not user-tunable at runtime.
  • sysconfig.SPECS — the runtime admin knobs (DB-override-or-default). A new admin-tunable value goes in SPECS; don't invent a fourth store. Each spec states when a change takes effect (applies, required): live keys are read where they are used, never at import (test-held). The scheduler's job intervals are SPECS keys too, edited on the Scheduler page, not the Configuration page.

The gate

Everything below must be green before a change is done (run via siftlode check): ruff + basedpyright (backend) · the lock check + tsc ×3 + eslint + prettier + knip + vite build (frontend) · vitest · pytest. The pytest lane runs in backend/docker-compose.test.yml — an ephemeral Postgres + the backend tree bind-mounted — so the DB-backed integration tests (the db fixture) actually run; a missing database is a hard failure, not a silent skip, unless a hand run asks for pure-logic only with SIFTLODE_TEST_REQUIRE_DB=0. See docs/development.md, and docs/gates.md for what each gate deliberately leaves out.