peter
82914b56ca
All three were measured before they were touched, and the diagnosis moved twice.
**Back from a Plex title played off Home landed on the Plex module's root.** One
click pushed three history entries: the page navigation, the sub-view opened by
the `jumpTo` hand-off, and — under StrictMode, whose effect body runs twice
before `setJumpTo(null)` re-renders — that same sub-view a second time. So the
first Back visibly did nothing and the second stranded the user on a Discover
page they had never visited.
A cross-module hand-off is the CONTINUATION of the navigation that brought you
there, not a second navigation, so it now REPLACES the page entry instead of
stacking on it (`useHistorySubview.open(view, {replace})`, asked for by the jump
target). Replacing is also idempotent, which is what disarms the StrictMode
double-run. The intent rides on `PlexJumpTarget` rather than being inferred,
because the header typeahead jumps from INSIDE the module, where the entry being
replaced would be a sub-view the user really was looking at.
**"Mást kérek" cycled nine cards and never left the resume tier.** Measured:
twelve presses, nine distinct titles, period nine, every one `tier: "resume"` —
the shelf and the surprise tier were unreachable by pressing the button. Two
causes multiplied: the tiers were tried in a fixed priority order over a 20-row
resume rail, so the button just walked down it; and the client's rolling
exclusion window of 8 guaranteed the wrap.
The press count now rotates which tier answers first (`start`), so each press
offers a different KIND of answer — the user's call, given the choice between
that, a wider window, and a surprise-only reroll. The fallthrough is kept, so a
press does not come back empty because the tier it led with had nothing. The
window is matched to the server's own cap rather than a smaller number of ours.
**A half-watched series on Home opened the show page.** A movie already went
straight to the player; only shows did not — and the comfort shelf and the hero
both resolved a show to its next episode while this rail alone did not, handing
back six seasons to choose between. The rail row now carries `next`, and the
client already played `next ?? card`, so this is a backend fix.
Affording it needed `queries.next_episode` to stop loading every episode of the
show into Python to pick one of them (236 rows for Friends, 227 for JAG) — three
ordered LIMIT 1 probes instead. The show→episode rule now lives in ONE function
(`rails.playable`), which is what the shelf, the hero and the rail all call; two
implementations are how they came to disagree.
Ten mutations run, all ten red for the right test — including a first pass where
the press count reached `api.discoverPick` and stopped there, invisible because
every Home test mocks that module. The slice now has its own URL test.
Verified in a clean browser tab against the live account: one Back returns to
Home, the rotation gives resume/comfort/surprise across nine presses with no
repeat, and Westworld opens at S1E1 rather than at its show page.
Backend conventions
The rules below are already followed across backend/app — they lived only in a few module
docstrings (demo.py, 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:
-
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. -
plex/,downloads/,sync/— 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.pyowns enqueue + the job state transitions (routes call it);plex/sync.pyis run by both the admin route and the scheduler;downloads/pipeline.pyis the worker's child pipeline. -
Flat
app/*.pycore modules — cross-cutting primitives.auth,sysconfig,quota,audit,notifications,userscope,realtime,ratelimit,progress, … are single-file primitives many layers import. They depend on nothing above them (a core module must never import aroutes/…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 owns its 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'sjobdbwrites, the same carve-out CLAUDE.md grantsquota) commits that session. Everything else flushes. SessionLocalisexpire_on_commit=False: after a rawUPDATE+ 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 — seeservice.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, orgreatest(col - 1, 0)withRETURNINGso the caller branches on the post-value under the row lock (service.incr_ref_count/decr_ref_count). - Download job status is a
JobStatusStrEnum (downloads/status.py), not bare strings. TheHOLDINGset defines which states hold aMediaAsset(so release accounting stays correct);STOPPED_BY_ROUTEis the route-initiated stop set. A worker child's terminal write goes throughservice.finalize_if_running(an atomicUPDATE … 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 inSPECS; don't invent a fourth store. (state.py'smaintenance_batchpredates this and is slated to fold intosysconfig— do not add more like it.)
The gate
Everything below must be green before a change is done (run via siftlode check):
ruff (backend) · tsc ×3 + eslint + prettier + knip (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; SIFTLODE_TEST_ REQUIRE_DB=1 there turns a would-be silent skip into a hard failure. See docs/development.md.