memby/CLAUDE.md

# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## What this is

**Memby** — an Android TV (Leanback) Emby client by **ponzischeme89**, written in Kotlin +
Compose for TV. It contains two surfaces over one shared data layer: the **client app**
(setup → profile chooser → home → player) and the **system screensaver** (`DreamService`,
labelled "Memby Screensaver"), which was the project's original purpose and still ships in
the same APK.

User-facing name is always **Memby**: `app_name`/`screensaver_name`/`developer_name` in
`res/values/strings.xml`, and on-screen copy.

**Except on the wire to Emby.** The `X-Emby-Authorization` header identifies the client as
**`MbyATV`**, not Memby — that header travels to whatever Emby does with its own logs, and
the product name has no business being what identifies a client to somebody else. It is
sent from two places and they must agree, or one television signing in both ways appears as
two clients: `MEMBY_CLIENT_NAME` in the gateway (`internal/config`) and the literal in
`EmbyServiceFactory`'s auth interceptor on the direct path. The `Version=` beside it is the
**television's app version**, which on the gateway path means `Credentials.ClientVersion`
threaded from the session's `X-Memby-Version`; it was a hardcoded `"1.0"`, so every device
in Emby's dashboard read as the same build and there was no way to tell which set was
behind. A request the gateway makes for itself (library sync, health probe, device cleanup)
carries no session, and reports the gateway's own `buildinfo.Version()` instead.

`Emby*` class names (`EmbyRepository`, `EmbyApi`, `EmbyServiceFactory`, `EmbyModels`) are
kept on purpose: those types model *Emby's* API, and renaming them would make the code
lie about what it talks to. App-identity types are `Memby*`.

## Repository layout

This is a two-language monorepo. `app/` and `benchmark/` are the Gradle build; `server/`
is an independent Go module (the **Memby gateway**) that Gradle does not know about, built
and run through Docker. `docker-compose.yml` at the root wires the gateway to Postgres and
Redis. The two halves are coupled only by an HTTP contract — see "Gateway mode" below.

## Build, install, test

Requires JDK 17 and the Android SDK. `deploy-debug.ps1` sets `JAVA_HOME` to Android Studio's
bundled JBR; do the same when invoking Gradle directly if the shell JDK isn't 17.

```powershell
.\gradlew.bat assembleDebug                 # build APK -> app/build/outputs/apk/debug/
.\gradlew.bat test                          # JVM unit tests (app/src/test)
.\gradlew.bat :app:testDebugUnitTest --tests "*MediaBadgesTest"   # one test class
.\gradlew.bat installDebug
.\deploy-debug.ps1 -Serial 192.168.20.3:41479   # force-stop, install, wake, relaunch
.\gradlew.bat :benchmark:connectedCheck     # macrobenchmarks; needs a connected TV
```

For the gateway (from `server/`):

```bash
go build ./... && go test ./...     # add -buildvcs=false on Windows if .git is unusable
docker compose up -d --build        # from the repo root; needs .env (see .env.example)
```

**Deploying the gateway to the NAS** is `deploy-server.ps1` (PowerShell 7):

```powershell
.\deploy-server.ps1                                   # local tree -> 10.0.0.213:/share/Docker/Memby
.\deploy-server.ps1 -SourceDirectory C:\src\memby -Destination /share/Docker/Memby-test
```

It tars the local `server/`, `docker-compose.yml` and `.env.example`, and streams them over
one SSH connection (interactive password; stdin carries the
archive, so OpenSSH prompts on the tty). The remote half stages into
`<destination>.new.$$`, builds, then swaps directories and waits for all three health
checks, restoring the previous release if anything fails. The named Postgres volume is
preserved — it never runs `compose down -v`.

**`.env.example` is the configuration.** It holds real values, and every deployment
overwrites the NAS's `.env` with the local copy (the old one is kept beside it as
`.env.previous`). The script requires `MEMBY_PORT=32768`, `MEMBY_ADMIN_TOKEN`,
`MEMBY_EMBY_URL` and `POSTGRES_PASSWORD` before activation, then confirms the admin token
reached the running container. The database volume is always preserved; deployment stops
before activation if the Postgres password differs from the deployed value, because a
credential change requires an explicit database migration. The local working tree is
deployed directly; no commit or push is required.

`local.properties` must contain `sdk.dir=...` when building from the CLI.

Lint has `abortOnError = false` (media3's `@UnstableApi` opt-in check would otherwise fail
the build), so lint failures do not surface at build time.

Unit tests are plain JUnit 4 with no Android/Robolectric dependency — logic that needs
testing must live in a pure function or a plain data class (`mediaBadges`, `HomeUiState`,
`millisecondsToTicks`, `ringColorFromHex`, `EmbyProfile` handling are the existing examples).

## Identity

One name everywhere: **`com.ponzischeme89.memby`** is the Kotlin package, the Gradle
`namespace` and the `applicationId`. Identity types are `Memby*` (`MembyApp`,
`MembyDreamService`, `Theme.Memby`).

Historical note, because old APKs and TVs still carry it: through v0.1.52 the package was
`com.mattcohen.embyscreensaver` and the `applicationId` was `com.mattcohen.embyclientsname`.
Both changed in v0.1.53. **`applicationId` is the install identity** — changing it makes
every TV treat the build as a brand-new app: the old icon stays until uninstalled, the
DataStore session is gone, and users sign in again. Treat any future change to it as a
migration, not a rename. adb commands, the benchmark `packageName` and `FileProvider`
authorities all derive from it.

**Versioning.** `versionCode` is derived from `versionName`: `major*10000 + minor*100 +
patch` (0.1.53 → 153). Bump both together — the in-app updater compares `versionName`,
while Android refuses an APK whose `versionCode` went backwards. `release.ps1 -Version`
rewrites both, so prefer it over editing the build file by hand.

**Releases.** APKs are self-hosted (NAS or any web server), not on a store. `release.ps1`
builds a signed APK and assembles `dist/out/` — `index.html` (landing page from
`dist/template/`), `latest.json` (the manifest the app polls) and the versioned APK.
Release signing reads `memby.keystore` and friends from `local.properties`; with no
keystore the build still succeeds but emits an unsigned APK and logs a warning. The key
matters more than the code: Android identifies an app by applicationId **plus** signing
key, so a changed key forces every user to uninstall and reinstall.

Every version bump is also a publish operation: update the version and changelog together,
commit the complete release, and push it to GitHub. Never leave a bumped version only in the
local working tree.

For direct TV deployment without publishing a release, `deploy-tv.ps1` builds and verifies
the signed release, connects over wireless ADB, installs it with `-r`, and launches the
Leanback activity. It reads the same signing settings from the current user's persistent
`MEMBY_KEYSTORE*` environment variables and defaults to the living-room Chromecast endpoint;
pass `-Device host:port` when Android rotates the wireless-debugging port.

`UpdateChecker` supports two sources, chosen by URL shape in `isManifestUrl` — a `.json`
URL is a static manifest, anything else is a Gitea host. `resolveApkUrl` lets a manifest
use a relative `apkUrl`. Both are unit-tested in `UpdateSourceTest`.

**`CHANGELOG.md` is the version history the TV shows.** It is read into
`BuildConfig.CHANGELOG_TEXT` at build time the way `LICENSE` and `NOTICE` are, parsed by
the pure `parseChangelog` in `ui/settings/VersionHistory.kt`, and rendered by Settings →
About as one collapsible release per entry. So a release edits one file and the history
stays readable offline. Keep the `## <version> — <date>` / `- bullet` shape; anything else
in the file is skipped as prose, and a bullet wrapped onto a second line is rejoined.

**An update is acknowledged once with a toast.** `ui/whatsnew/whatsNewDecision` compares the
running build with `Settings.whatsNewSeenVersion`, and `AppRoot` briefly says “Memby has been
updated to version …” over the launcher before recording it. The record is device state,
deliberately not a synced preference: what is new is a property of the APK on *this* set.
Two quiet cases matter: a **fresh install** has not updated from anything, so setup records
the current build without announcing it; and a signed-out set with an older record waits
until somebody signs in, because the notice belongs over the launcher. The changelog is no
longer part of this decision — release history remains available in Settings → About, while
local or unreleased builds still receive the same one-time update acknowledgement.

**Forced updates are server-controlled.** `server/internal/appupdate` decides `none` /
`optional` / `mandatory` from the client's `X-Memby-Version` header against an
operator-set policy (admin page → App updates). `HomeViewModel.checkForAppUpdate` runs on
every launch and `ui/UpdateScreen.kt` renders the verdict — mandatory covers the whole
home screen with `zIndex(10f)`, swallows Back and offers no dismiss. Two safeguards worth
preserving: a client with an unreadable version is never forced (it could not escape the
prompt), and the client ignores any verdict without a `downloadUrl` (`isActionable`), so a
half-configured policy cannot produce a blocking screen with a dead button. The verdict
must stay out of `/v1/home`, which is cached per user while this answer varies per client
build.

**A retired build must be told why it was signed out.** The destructive floor
(`destructiveUpdateFloor`) deletes the session on the next authenticated request and answers
401; a retired build's sign-in is then refused with 426. The television only saw the sign-out
— so it drew a sign-in form the gateway would refuse, and the mandatory update screen was up
to `UPDATE_CHECK_INTERVAL_MS` (an hour) away, force-closing the app being the only way
through, since a fresh launch checks for updates before it draws anything. Both refusals
carry `X-Memby-Update-Required`, so `RequiredUpdateInterceptor` on the gateway client
publishes it through `update/RequiredUpdateSignal` and `AppRoot`'s check loop waits on
*either* the hourly interval or that signal. Things to preserve:

- **It is an interceptor** because the refusal lands on whichever request happened to be in
  flight — the status poll, a home refresh, a sign-in — and only one of those has any reason
  to know about update policy. The signal replays one value, because it is commonly reported
  before the check loop is waiting on it.
- **The refusal is written to disk** (`Settings.requiredUpdateVersion`, via
  `RequiredUpdateGuard` on the service locator), because it is announced exactly *once*: the
  401 that deletes the session carries the header and every 401 after it is an ordinary
  missing session. In-memory only, a television told and then restarted had nothing left to
  learn it from but the launch check — which is bounded by `UPDATE_CHECK_TIMEOUT_MS` (2.5s)
  and, on missing it, put the viewer back on the welcome and sign-in screens. It is written
  by the locator rather than by a screen for the same reason the interceptor exists: nothing
  that knows about update policy is necessarily composed when the refusal arrives.
- **Only the gateway may withdraw it.** A verdict that is not a required update clears the
  flag; a failed check never does, because an unreachable server is no evidence about which
  builds it accepts. `requiredUpdateSatisfied` is the one exception and it is pure and
  tested — the build the refusal demanded is now the build running, which is what the moment
  after a successful self-update looks like.
- **`RetiredBuildScreen` is what the television shows meanwhile**, ahead of sign-in,
  profiles, the launcher and the null-settings case alike. There is no attempt budget any
  more: giving up used to hand the viewer a sign-in form as the *final* answer, and every
  screen underneath this one is something the gateway would refuse. The loop asks every
  `UPDATE_REQUIRED_RETRY_MS` for `UPDATE_REQUIRED_FAST_ATTEMPTS`, then settles onto
  `UPDATE_REQUIRED_BACKOFF_MS`, and the screen's Try again wakes it through the same channel
  a refusal does.
- **Every refusal wakes the loop, including a repeat.** The 401 that retires the session and
  the 426 that refuses the sign-in after it name the same version, and the second is the one
  a viewer is standing in front of — filtering it as already-handled is what left a
  television on a form it could not get through until the next hourly check.

## Architecture

**Manual DI.** `ServiceLocator` (initialised in `MembyApp`) holds the single `SettingsStore`
and `EmbyRepository`. Activities, composables and `MembyDreamService` all read from it —
there is no DI framework and no per-screen repository construction.

**Backend selection is build-time config.** Two Gradle properties in `gradle.properties`
become `BuildConfig` fields, both read through `data/ServerConfig.kt`:

- `memby.gatewayUrl` → `MEMBY_GATEWAY_URL`. Non-blank puts the app in **gateway mode**.
- `memby.serverUrl` → `EMBY_SERVER_URL`. The Emby address for the direct path; when set,
  the repository's `activeServerUrl` prefers it over the persisted `Settings.serverUrl`
  and `SetupScreen` hides the address field.

Prefer `activeServerUrl` over `snapshot.serverUrl` in new repository code, or a hardwired
build silently falls back to a stale saved address. `resolveServerUrl` holds the
precedence rule as a pure function so it can be unit-tested.

**Gateway mode.** `EmbyRepository` is dual-path: every method starts with a
`if (ServerConfig.isGateway)` branch that calls `GatewayApi`, then falls through to the
original Emby code. Both paths must keep working — the direct path is the fallback when
the container is down. Specifics worth knowing:

- The gateway forwards **Emby's item JSON verbatim**, so `BaseItem` is the single item
  model in both modes. Only the envelope differs (`data/model/GatewayModels.kt`).
- `Settings.token` holds the *gateway* token in gateway mode and the Emby token
  otherwise; `Settings.serverUrl` likewise holds whichever backend was signed into. No
  separate storage slots.
- `supportsBatchHome` drives `HomeViewModel`: gateway mode fetches all four rows with one
  `getHome()` call, direct mode keeps the four-way parallel fan-out.
- **Rows are server-composed.** `/v1/home` returns a `rows` array (id, title, kind, items)
  and `MainActivity.serverHomeRows()` renders it verbatim, so a new row type ships without
  an app release — an unknown `kind` falls back to poster cards rather than disappearing.
  `state.rows` is empty on the direct path, where `homeRowsFor()` composes rows locally.
  Two things are easy to miss: rows hold their own copies of items, so
  `HomeViewModel.updateUserData` must map over `rows` too or an optimistic favourite won't
  show on a recommendation card; and `loadBatchHome` keeps the previous rows when a
  response arrives with none, because the gateway omits recommendations while they build.
- **Continue Watching and Next Up are one row**, merged by `api/continue_watching.go`.
  They answered the same question — "what am I in the middle of?" — and splitting them
  meant a show moved between rows the moment an episode ended, which is exactly when
  somebody most wants the next one. Merging is not concatenation: both lists are ordered
  by recency, so the row is a *merge of two sorted lists*, never a sort of their union —
  Emby's order within each is the useful part. That needs a time per card, and a Next Up
  episode has none of its own (it is unwatched), so `recentlyPlayedSeries` asks for the
  household's recent plays and each episode is placed by when its **series** was last
  watched. Things to preserve: a series in both is represented by its resume item, since
  somebody eleven minutes into an episode wants that episode; an undated card never
  displaces a dated one and falls back to the resume half, so a failed lookup degrades to
  the order the launcher had when they were two rows rather than to nonsense; and the
  rule exists twice, in `data/ContinueWatching.kt` for the direct path, pinned by
  deliberately parallel tests (`ContinueWatchingTest`, `continue_watching_test.go`) —
  with no gateway there is nobody to ask, and the row must not differ depending on
  whether the container is up. The client still folds a `nextup` row it is handed into
  Continue Watching (`foldNextUpIntoContinue`), because the home cache written by the
  previous build is what a TV draws before its first refresh lands.
- **Continue Watching is not ranked** (`progressRow` in `api/ranking.go`).
  Every other row goes through `personalizeTitles`; this one keeps Emby's order, which is
  most-recently-watched first and the entire reason the row is useful. Ranking it by
  taste is not a neutral reshuffle: an episode's row payload carries no studios, cast or
  collection, its `Type` has no affinity evidence behind it, and its runtime fits a
  session profile built from features badly — so films sorted to the front, episodes
  sorted past the visible cards, and a show somebody had just watched an episode of read
  as having disappeared. The diversity caps and the exploration shuffle in `WeightedRank`
  compound it. `TestProgressRowsKeepEmbyOrder` pins it.
- `HomeCache.rows` persists them for cold start. New fields there need defaults — an
  existing install decodes a cache written by the previous build.
- Image URLs are built by the private `imageUrl()` helper. Coil fetches plain URLs with no
  interceptor, so the credential rides in the query string either way — `t=` for the
  gateway proxy, `api_key=` for Emby.
- Video always direct-plays from Emby. The gateway returns a URL; it never proxies a
  stream. Don't route playback through it.
- Search is dual-path like the rest: `/v1/search` on the gateway (Postgres full-text,
  falling back to Emby before the first import), `SearchTerm` on `Users/{id}/Items`
  directly. `ui/search/` renders it — see "Search" below.

The wire contract is pinned from both ends: `GatewayPayloadTest.kt` / `ServerHomeRowsTest.kt`
(Kotlin) and `internal/api/api_test.go` (Go). Change a field name or a row `kind` and one
of them should fail.

**Imported library.** `server/internal/library` copies Emby's catalogue into
`library_items` (payload stored verbatim as JSONB, hot fields promoted to columns for
filtering plus a generated `tsvector`). Search and the recommendation candidate pool read
from it, falling back to Emby when it is empty — so both paths must keep working. It is
imported with `EnableUserData=false` on purpose: the table is shared by the whole
household, so watched/favourite/resume state must never be cached there and still comes
from Emby live. A full import mark-and-sweeps on `synced_at`; incremental uses
`MinDateLastSaved` with a minute of overlap.

**External ratings** (MDBList) are bought by the day, not by the request, so the design
question is never "how fast can we fetch" but "how few times must we ever ask". The answer
is that a title is fetched once and kept: `external_media_ratings` holds the raw provider
response permanently, `ratingsNeedRefresh` renews a scored title after 30 days and an
empty answer after 3 (a new release genuinely gains scores), and a stored value is *always*
served immediately — a refresh happens behind the viewer, never in front of one. Redis
still fronts it, but only to save the Postgres read. Things to preserve:

- **A row carries its own ratings.** `decorateItemRatings` injects `MembyRatings` into the
  item JSON of home rows, search, related and `/v1/items/{id}`, so a card draws its scores
  as the row appears rather than when D-pad focus reaches it. It attaches **only what is
  already stored** — one indexed read for a whole launcher, and never an external request
  on the request path. `/v1/items/{id}/ratings` still exists for a title nobody has looked
  up yet, and the client (`ItemRatingsStrip`) falls back to it on focus.
- **Identity is the expensive half, so it is remembered.** MDBList is keyed by tmdb/imdb
  id, which Emby only reveals in a `ProviderIds` lookup — a request per card. `ProviderIds`
  is therefore in the library import's `syncFields`, and `item_rating_refs` records what
  each Emby item turned out to be as televisions navigate, so the index fills in without
  waiting on a full re-import. `ratingKeyFor` holds the rule the live lookup uses: films
  and shows only, an episode is rated as its series, tmdb wins over imdb.
- **The warmer is fed by navigation and bounded three ways.** Rows report the titles they
  could not decorate; the queue is bounded and deliberately *lossy* (a dropped title is
  offered again the next time somebody scrolls past it), fetches are paced, and
  `claimRatingsBudget` caps the day — a 429 stops it for an hour. A household's allowance
  is spent on titles it actually looks at, in the order it looks at them.

**Maintenance mode** gates the whole `/v1` subtree (that's why `Routes()` builds a
separate `v1` mux) with a 503 carrying `maintenance: true`. `/healthz`, `/readyz` and
`/admin` sit outside it deliberately. State lives in Postgres and is cached in memory,
re-read every 30s. Client side, `parseMaintenanceMessage` pulls the operator's message out
of the 503 body (trusting only the known `message` field, truncated) and
`HomeUiState.maintenanceMessage` — distinct from `statusMessage`, which is the ordinary
slow-connection banner — swaps the whole content area for `ui/MaintenanceScreen.kt`. The
navigation rail stays mounted beside it so Settings and Switch user still work, and the
retry button takes `contentFocusRequester` (with `focusProperties { left = … }` back to
the rail) because otherwise D-pad focus has nowhere to go once the rows are gone.

**Service alerts.** `/v1/status` is the only thing an open app polls continuously (10s,
`MaintenanceMonitor`), so it doubles as the push channel: alongside maintenance state it
carries an `alerts` array, and `ui/ServiceAlertBanner.kt` drops one in as a full-width bar
across the top of the screen, broadcast-notice style (it spans the navigation rail too).
Alerts come from two shapes of producer. **Derived**: `api/alerts.go` announces an episode
whose Sonarr air time has passed but which Emby has not imported yet ("aired, coming
soon"), recomputed per poll from the *cached* airing-today calendar, so polling clients
never cost a Sonarr request. **Events**, which are published into one shared Redis list
(`publishAlert` / `publishedAlerts`, also in `alerts.go`) and served from it until their
window closes — a list rather than a push because the gateway holds no connection to a
television, and a window is what lets a set that was off or in the screensaver at the time
still hear the news. Four publishers today:

- `api/radarr_alerts.go` — a film Radarr just imported. `POST /hooks/radarr` is the "On
  Import" webhook and the one thing that pushes *into* the gateway, guarded by
  `MEMBY_RADARR_WEBHOOK_TOKEN` (unset ⇒ 404, the stance `/admin` takes) and mounted
  outside both the auth middleware and the maintenance gate, because an event dropped
  during maintenance is lost rather than delayed. A quality upgrade is deliberately
  silent: the film was already there.
- `AnnounceLibrarySync` in `api/server_alerts.go`, hung off `syncer.SetAfterSync` in
  `main.go` — "24 titles added or updated". Only a run that *changed* something is
  announced; the import is scheduled, most passes find nothing, and an hourly "no news"
  banner would train viewers to ignore the real ones.
- `AnnounceDeployment`, same file, published by `deploy-server.ps1` through
  `POST /admin/api/deployment-alert` — "Memby server in deployment mode". **Where it is
  published from is the design**: the deploying script calls the gateway it is about to
  replace, using the admin token from the *deployed* `.env`, before the image is built.
  That build is the several minutes during which the old gateway still answers and every
  open TV polls `/v1/status` at least once. Announcing at the swap would be too late twice
  over — nothing is left to publish with once the stack is down, and Redis runs with
  `--save "" --appendonly no` and no volume, so the swap discards anything published but
  not yet collected. It is best-effort on both sides: a first deployment has no previous
  token to announce with, and a deployment must never fail over a banner.
- `WatchEmbyReachability`, same file — "Emby has stopped communicating" and the matching
  "back online". Only transitions are announced, and only after
  `embyFailureThreshold` consecutive failures, because one timeout is a hiccup and
  repeating an outage every minute would bury everything else. This is the alert that
  earns the banner its place over playback: video direct-plays from Emby, so when Emby
  stops answering the film stalls with no explanation, and the gateway is still up to
  say why. `MEMBY_EMBY_HEALTH_INTERVAL=0` turns the probe and both banners off.

`mergeAlerts` interleaves derived and published alerts newest-first and caps at
`maxAlerts`, which is why every alert carries a timestamp. Alerts also carry their own
`label` (the banner's eyebrow — "JUST AIRED", "NEW MOVIE ADDED", "SERVER NOT RESPONDING"),
so a new kind of news reads correctly on an app that predates it; a client that receives
none falls back to the episode wording. Things to preserve:
the server has no idea which TVs saw what, so the client dedupes by id against
`SettingsStore.markAlertSeen` (persisted, or every relaunch replays yesterday's news); an
alert is only *offered* until the banner calls `alertShown` — nothing is persisted and no
dismissal timer runs before that, so one arriving behind the screensaver waits rather than
being consumed by nobody, and `pendingAlertExpired` drops it once the gateway stops
offering it. The status loop itself runs under
`ProcessLifecycleOwner … repeatOnLifecycle(STARTED)`, so a backgrounded app stops polling
entirely instead of hitting the gateway every 10s at a TV nobody is watching. The banner is
never focusable and
times itself out after `MaintenanceMonitor.ALERT_VISIBLE_MS` (10s, with a ring counting it
down — take the duration from that constant, or the ring and the timer drift apart),
because stealing D-pad focus mid-browse is worse than a missed notice;
and alerts are suppressed under maintenance and under a mandatory update, which own the
screen.

**The bar appears over playback too**, not only over the launcher: `PlayerActivity`
mounts the same composable in a `ComposeView` (`player_service_alerts` in
`activity_player.xml`, declared before the loading and error overlays so those cover it).
`alertsSuppressed` starts *true* and is cleared only by `hidePlaybackLoading`, which is
reached once the preroll is over and the first frame is up — an alert composed behind an
overlay would be marked seen by a viewer who never saw it, which is the same failure
`alertShown` exists to prevent. Because it now covers somebody's film, the bar is
deliberately small (76dp), near-black, and eases in over ~680ms rather than snapping
down. It shows the **Emby mark**, not item artwork: a library refresh and an outage have
no artwork, and one constant mark reads as "your server is talking" where a poster made
every alert look like a different feature. The wire still carries `itemId`/`imageTag`;
the client just does not render them. `MEMBY_SONARR_ALERT_WINDOW=0` turns them off without touching the schedule row,
and `MEMBY_RADARR_ALERT_WINDOW=0` does the same for movie imports.

**Emby outage bar.** An alert is news; this is *state*, and both are needed. `internal/api/
emby_health.go` caches what the reachability probe found and `/v1/status` publishes it as
`emby: {monitored, reachable, since, checkedAt, retrySeconds}`; `ui/EmbyOutageBanner.kt`
renders it as a persistent red strip across the top, on the launcher *and* over playback,
counting down to the next attempt. The case it exists for is a television switched on
twenty minutes into an outage: it was never told anything, the film will not start, and
the alert that announced it has long since fallen out of its window. Things to preserve:

- **`monitored` is load-bearing.** `MEMBY_EMBY_HEALTH_INTERVAL=0` turns the probe off, and
  a client that trusted `reachable` alone would then show a permanent red bar on a server
  that is working. The server sends `reachable: true` in that case as well, but do not
  remove either half.
- **The bar's threshold (`embyOutageThreshold`, 2) is lower than the alert's**
  (`embyFailureThreshold`, 3) on purpose. The announcement is a one-shot that cannot be
  taken back, so it waits to be sure; the bar clears itself the moment Emby answers, so
  being early costs a minute of red rather than a false claim left standing.
- **An outage already on screen keeps its countdown.** The status poll runs six times per
  retry, so recomputing the deadline each time would reset the number every ten seconds
  and it would never reach zero. `nextOutageState` is the pure rule and is unit-tested.
  It counts in `SystemClock.elapsedRealtime`, not wall clock — a TV correcting its clock
  mid-outage must not throw the countdown.
- **The news bar yields the strip while it is up** (`ServiceAlertBanner(suppressed = … ||
  outage != null)`), in `MainActivity` and in `PlayerActivity` alike. They occupy the same
  place and one of them says it better.
- **The direct path has its own probe.** With no gateway there is nobody to ask, so
  `MaintenanceMonitor.launchDirectEmbyProbe` pings `System/Info/Public` on the same minute
  — unauthenticated on purpose, since a probe needing a token would report a stale session
  as a server outage.

**My Alerts belongs to a person, so it lives in the user picker.** A service alert is the
house being told something; these are one viewer's own news (a followed show returning),
stored per user on the gateway and following them to whichever television they sign into.
`ui/alerts/AlertsPage.kt` is the full page and the user menu in `UserSwitcherOverlay` is the
way in, beside Manage users. It replaced a bell in the corner of the launcher, which was
drawn only on Home and cost a focus target on every set whether or not there was anything
behind it. Things to preserve:

- **The badge counts alerts, not unread ones** (`alertBadgeLabel`, pure and tested). An
  alert that has been read but not dismissed is still sitting there, and a badge that
  cleared itself the moment somebody glanced at the page would never agree with the list
  underneath it. `AlertBadgeMax` is what stops the pill growing wider than its row.
- **The badge is drawn twice on purpose** — on the "Switch user" rail item and on the My
  Alerts row inside the picker. The page is one level in now, so without the mark out on the
  rail nothing on the launcher would ever say there was news waiting.
- **A press dismisses, and the focused row says so.** This is the only page whose whole job
  is emptying itself; a confirmation press per alert is what made the panel it replaced not
  worth opening. Focus marks read, so nothing has to be pressed to clear the "new" flag.
  "Dismiss all" is the same per-alert call in a loop — the gateway has no bulk route — and
  empties the list optimistically, or a row lingers under a thumb that will press it again.
- **The page is stateless**, like `SignInContent` and the detail panes: `MainActivity` owns
  the list and the requests, which is what lets `AlertsPageScreenshotTest` render it (and
  the user menu carrying its badge) with no server → `build/screenshots/my-alerts/`.

**Search** (`ui/search/`) is a two-pane instant-search destination on the rail: a fixed
6×6 on-screen keyboard on the left, a results grid on the right that updates as you type.
Nothing is ever "submitted". `SearchViewModel` runs one pipeline — `debounce(250)` →
`trim` → `distinctUntilChanged` → `collectLatest { repository.search(it) }` — and
`collectLatest` is the load-bearing part: it cancels the in-flight request, so a slow
response for a prefix can never overwrite the results for what was typed after it.
Searching starts at two characters (`shouldSearch`); one letter matches half a library.
`rankSearchResults` is a pure, stable sort that only lifts exact/prefix/word-boundary
title matches above the backend's own relevance order — it never re-sorts alphabetically,
and it keeps weak matches rather than showing an empty pane. A small access-ordered map
caches results per query for the session, so backspacing is instant.

**Every search the tab performs is recorded, and the gateway is what records it.** It used
to depend entirely on the television posting to `/v1/search/history` after a result landed,
which meant a query answered from the client's own cache, one whose post failed, or one
from a build that predates the call was never written down at all — and the table feeding
the recent-searches row and future per-user ranking was a partial record of what the
household looks for. `handleSearch` now calls `recordSearchQuery` itself, before the Redis
lookup, so a cached answer counts the same as one that reached Emby. Things to preserve:

- **The write is detached from the request context.** Instant search cancels the in-flight
  request on every keystroke, so a write hung off `r.Context()` would be abandoned for
  exactly the searches somebody typed fastest. It is also fire-and-forget: a search whose
  record failed still returns results, and the failure is DEBUG for the same reason the
  search line is.
- **`store.SearchDedupeWindow` is what makes two writers safe.** The handler and the
  client's post both describe one search, and the POST route is still there because an
  older APK is the only thing that records at all. An identical query inside the window is
  the same search; a minute later it is its own row.
- **`searchQueryRecordable` is the one rule both routes apply**, so a query `/v1/search`
  records is exactly one `/v1/search/history` would have accepted. Length is counted in
  runes, or a title in Japanese is rejected at a third of an English one's length.

**And the console can read it back** — `/admin/searches`, in the Insights group beside Row
engagement, over `internal/api/admin_searches.go` and the store queries in
`internal/store/searches.go` (where the writer moved to, so one table's rules sit in one
file). It is **two tables of the same rows on purpose**: the summary groups by
`lower(query)` and answers "what does this house look for", which is what a library is
organised against; the log is uncollapsed and newest-first and answers "what happened just
now", which is the one to read when somebody reports that search is not finding something,
because it shows the query as it was typed, by whom, and when. Things to preserve:

- **The widest window is the retention period.** `searchWindowDays` is derived from
  `store.SearchRetention` rather than written down, because `RecordSearch` prunes to it —
  a page offering 90 days would draw a flat line for two thirds of it. A tile states the
  retention for the same reason: a quiet week and a window that has aged out look identical.
- **`SearchTotals` is its own query, not a sum of the table above it.** The summary is
  capped at `searchTermLimit`, so adding it up would report the top twenty-five's total as
  the household's, wrong by however long the tail is.
- **Names are resolved in Go from `KnownUsers`, not joined per row**, and an id with no
  session left keeps its row wearing the id — the query is what the page is for, and a
  viewer whose sessions have expired is still one searcher rather than nobody.
- **Nothing on it is editable**, the stance every insights page takes. It also cannot
  delete: the 30-day prune is the only thing that removes a row.

**A genre is browsed, not searched.** The chips on the empty state ran their own label
through `/v1/search`, which is a text query: "Drama" matched a film *called* Drama, anything
with the word in its overview, and — relevance being a score rather than a rule — a
scattering of titles not in the genre at all, while missing most of the ones that were. A
chip now opens `GET /v1/genres/{genre}/items` (`server/internal/api/genres.go`,
`EmbyRepository.browseGenre`), which filters on Emby's `Genres` parameter and answers a page
at a time. Things to preserve:

- **It is a mode, not a query.** `SearchUiState.genre` sits beside the query rather than
  pretending to be one, which is what lets the pane head itself "Comedy" instead of "Search
  results for “Comedy”" and lets Back step out of the shelf without clearing something
  nobody typed. Typing supersedes it; `runSearch` returns early while a genre is open, or
  the empty-query transition that opening one causes would wipe the shelf it just filled.
- **Paging must not repeat or skip a card**, which is why both paths sort on
  `PremiereDate,SortName` rather than a date alone — two titles sharing a premiere could
  otherwise swap places between requests, and the scroll would show one twice and the other
  never. Newest first, because the alphabet is not an answer to "show me Comedy".
- **Two rules end the scroll and both are needed** (`hasMoreGenreItems`, pure and tested):
  reaching the total is the ordinary end, and a page shorter than the one asked for is the
  other — a backend that would not count says nothing useful with its total. `genreTotal` on
  the server is the same judgement from the other side, for an Emby that did not count.
- **A page is appended by its own offset**, never by order of arrival: a response for an
  offset already scrolled past, or for a genre the viewer has left, is dropped rather than
  pasted into the middle of the grid. A page that fails part way down keeps what is on
  screen and simply stops paging.
- **The scroll trigger is a `snapshotFlow`, not a composable read.** The last visible index
  changes on every frame of a scroll, and reading it in the body would recompose the grid
  the whole way down a genre — the same rule as the animation one above. It asks
  `LOAD_MORE_ROWS_AHEAD` rows early, since a request that starts when the viewer arrives at
  the end is one they watch.
- **Something has to take the focus the chip was holding**, because opening a shelf unmounts
  the whole discovery pane. The grid claims it when the first page lands, and an empty or
  failed genre hands it back to the keyboard rather than leaving a television with nothing
  focused.
- **Episodes are excluded on both paths.** An episode inherits its series' genres, so
  including them fills a page with twenty entries of one comedy and buries the rest.
- **Movies and TV Series have their own full-width genre browser.** A fixed row of colourful
  mini cards is the first focus target on both destinations; it is deliberately a product
  catalogue rather than whatever genre names happened to arrive in the home rows, so its
  order and availability never jump around during refresh. Neighbouring Emby labels are
  merged where they answer the same browsing intent (`Action|Adventure`,
  `Science Fiction|Sci-Fi|Sci Fi|Fantasy`, `War|History`) using Emby's pipe-delimited genre
  filter. `ui/genre/` keeps the resulting pages in memory, preserves the active category
  behind a detail page, returns focus to the title that was opened, and consumes
  `HomeViewModel.favoriteChanges` so a Favourite press and its possible rollback reach the
  paged copy immediately. Its `type=Movie` / `type=Series` query is still enforced by the
  gateway and on the direct Emby path, so no category can mix the two grids.
- **The gateway path degrades to a keyword search on the *first* page only**, so a set on a
  new build talking to a gateway that predates the route still shows something. A later page
  does not: a gateway that answered page one and failed on page two is having trouble, not
  missing the route, and search results pasted onto the end of a genre would be nonsense.

Focus is the hard part and is explicit: the leftmost keyboard column goes to the rail, the
rightmost goes to the results grid, the grid's first column goes back to the *last key
used* (a `FocusRequester` attached to whichever key that is), and the grid has a
`focusRestorer`. Back moves results → keyboard → genre → leave, one step per press.
Physical keyboards and phone-remote apps feed the same state through one
`onPreviewKeyEvent` that consumes only printable characters and backspace — D-pad and Back
must fall through. The voice button needs the `android.speech.RecognitionService` entry in
the manifest's `<queries>`, or `isRecognitionAvailable` returns false on Android 11+ and
it hides itself on devices that actually support it.

**Row analytics.** `data/analytics/RowAnalytics.kt` buffers impression/focus/select events
with dwell timing (injectable clock, unit-tested) and `HomeViewModel` flushes every 20s,
on `ON_STOP`, and on dispose. Fire-and-forget by design — `reportRowEvents` swallows
failures, because telemetry must never surface on a TV. Aggregates are read at query time
in `store.RowStats`; raw events are pruned after 90 days.

**Server logging** answers "who did what, from which television, on which build". Three
pieces make that true and each is easy to undo:

- `internal/logging` writes an **aligned console line** — timestamp, level, message,
  fields — because a labelled `time=` in front of the message is noise in every viewer
  that already has a timestamp column. Fields are ordered by `fieldRank`: identity
  (`component`, `user`, `device`, `client`) first so it can be read as a column, the
  constant `version` and the `error` last. `MEMBY_LOG_FORMAT` switches to `logfmt` or
  `json`; the ring buffer the admin page reads is fed the same records in every format.
- `internal/api/logcontext.go` carries a **`*requestIdentity` in the request context**.
  `withLogging` creates it from the route and the client headers; `authed` fills in the
  viewer and television once the session resolves; both the handler's own events
  (`s.loggerFor(ctx)`) and the closing request line read it. It is a pointer precisely so
  the outer middleware sees what an inner layer learned — `r.WithContext` in the handler
  would not reach it. Prefer `s.loggerFor(ctx)` over `s.log` anywhere a request is in
  scope, or the line lands with no idea whose it was.
- `componentFor(path)` is **the part of the app a call came from, derived from the
  route** rather than declared by the client: the TV would have to thread a surface name
  through every repository method, and this way an old APK is attributed correctly too.
  Keep it a pure function with a case per area, and add to the test when a route lands.

The events that matter are logged as events, not inferred from request lines: sign-in
(and rejection), sign-out, device removed/renamed, `playback requested` / `started` /
`stopped` (with `watched=`), `next episode resolved`, `update offered`, media requests,
maintenance and feature changes, library syncs. Playback reports carry only an item id,
so `playbackTitles` (bounded, in-memory, lossy on restart) remembers what
`/v1/items/{id}/playback` called the thing, which is what lets a stop be logged by name.
Ten-second progress reports and per-keystroke searches are DEBUG on purpose.

`internal/buildinfo/VERSION` is embedded and appears on every line, on `/healthz` and in
the admin rail — bump it with a meaningful server change; nothing else identifies which
tree a container was deployed from.

**Admin interface** is `server/internal/api/admin/` — a shell, a stylesheet, a shared
runtime and one fragment per page, all embedded and composed by `admin_console.go` at
start-up into finished bytes per URL. No build step and no CDN: a strict no-dependency
console is still the whole point, and serving a page is still a write of a `[]byte`.
Guarded by `MEMBY_ADMIN_TOKEN`; unset means every `/admin` route 404s. It polls
`/admin/api/status` every 30s and stops entirely on a hidden tab.

It was one HTML file holding every screen at once, all but one of them hidden, which is why
opening `/admin/logs` also sent the accounts settings editor and the feature grid, and why
each page read as a pile of unrelated controls. Things to preserve:

- **`adminNav` is the only place a page is declared.** The rail, the page titles, the set of
  legal `/admin/<page>` URLs and the render loop all read it, so a page cannot be in the
  menu and 404, or be reachable and unnamed. Adding one is an entry there plus
  `admin/pages/<id>.html` and `<id>.js`; a fragment with no entry panics at start-up rather
  than sitting there looking maintained.
- **Hidden pages are addressed by a route that carries something else in the path.**
  `/admin/accounts/{userID}` renders the `account` fragment; `/admin/account` is a 404 and
  `cleanInstallerDestination` refuses it, because a sign-in returning there would land on a
  page about nobody. That route sends the login form back to `/admin/accounts` instead.
- **The page fragments contain no inline styles.** Everything is drawn from the component
  vocabulary in `admin.css` — card, tile, field, check, tag, chip, list, table, glyph. A
  screen that needs a look of its own is a missing component, not a licence for a style
  attribute; the previous page had four hundred lines of CSS and still reached for
  `style="..."` on every second element.
- **Six tones, and three of them mean nothing.** Green is the verdict colour, amber is look
  at this, red is wrong — and beside them are info (blue), note (violet) and data (teal),
  which carry no judgement at all. They are what lets a page say a person is a different
  kind of thing from a television without every coloured element on screen reading as a
  warning. A tone is passed, never derived: the same idea wears the same colour on every
  page it appears on (the library is teal, a person violet, a television blue), which is
  most of what makes twelve screens read as one console. A verdict tag also carries a dot in
  its own colour, because tone alone is no signal to somebody who cannot separate the green
  from the amber.
- **Icons live in `core.js` and nowhere else** — one stroked path on a 24×24 grid each, the
  same shape the rail's marks take. A fragment asks for one with `data-icon` (plus
  `data-icon-tone`) on any element and `Admin.decorate` fills it in once, when the page has
  parsed; anything a poll redraws asks with `ui.glyph`, or the mark is wiped on the first
  refresh. An unknown name draws nothing rather than a broken box: a mark is decoration, and
  a typo in one must never be what an operator notices about a page.
- **`core.js` owns the transport, the error banner and the refresh loop**; a page registers
  `Admin.onStatus` (called with each status poll) or `Admin.onRefresh` (its own request
  alongside it). `Admin.settled`/`fill`/`check` are the one rule that must not be dropped:
  never redraw markup the operator is working inside, or every poll takes a half-typed
  field or an open select away mid-edit.
- **Nothing on the overview page is editable.** It answers "is anything wrong" and links to
  the page that can do something about it. A screen that both summarises and changes state
  is where an accidental click lives.

**Explaining a recommendation** is `recommend/explain.go`: `Why(profile, item, limit)` is a
pure function turning the learned weights into the phrases a detail page shows. It is kept
apart from `Score` on purpose — the scorer decides *order* and may be opaque, this decides
*wording* and must never invent an affinity, which is what `reasonFloor` and the
unit tests enforce. `PersonWeights` exists only for this: casting is a good reason to tell
someone about a title and a poor reason to rank by it. `api/related.go` serves it beside
Emby's similarity list at `GET /v1/items/{id}/related`, cached per user and item because
building the profile costs the same Emby fan-out the home rows pay for.

**Recommendations** live in `server/internal/recommend`: `profile.go` is pure scoring
(recency-weighted genre/studio affinity, exclusion of anything seen) and `engine.go` does
the Emby fan-out. Both are unit-tested without a network — `engine.go` takes a narrow
`Source` interface so tests inject a fake. The engine never runs on the home request path:
rows come from the `r:<userId>:rows` cache, and a miss triggers a deduplicated background
rebuild while home returns immediately. That key is intentionally outside the `u:`
namespace that mutations wipe; only a finished playback retires it.

**"Because you watched …" rotates, because the top of a watch history does not.** The rows
were anchored to the two most recent seeds, and the head of history is a resumable title
plus whichever series the household is part-way through — neither of which moves for weeks,
so the same two rows came back day after day. `selectSeeds` (pure, tested) instead cuts the
most recent `SeedPool` seeds into `MaxSimilarRows` equal bands and draws one from each by
`dailySeed(userID)`. Things to preserve: it is a rotation *within recency bands*, never a
shuffle of the window, so the first row is still anchored to something watched lately and
the rows below it reach further back; the same day always yields the same seeds, because
rows are rebuilt on every cache miss and a set that re-picked each time would change under
somebody browsing; the last band takes the remainder, so a pool that does not divide evenly
still reaches its oldest entry; and a history shorter than the pool falls back to plain
recency rather than pretending to rotate. `similarRow` also runs `diversifyRanked` over its
cards with the same daily variation, the way curated shelves do — a row that keeps its seed
across two days must not present the same posters in the same order. `MEMBY_RECOMMEND_TTL`
(24h) is what makes the rotation daily in practice: the seed only changes at a rebuild.

**`EmbyRepository`** is the only place that talks to Emby. It keeps a `@Volatile` `snapshot`
of `Settings` collected from DataStore so synchronous callers (URL builders,
`rotationIntervalMillis`) don't suspend, and it caches the Retrofit `EmbyApi` instance,
rebuilding only when the base URL changes. All image and stream URLs are built here with
`api_key` appended. Errors reaching the UI go through `friendlyEmbyError` — never surface
raw HTTP bodies, which can contain tokens (the OkHttp logging interceptor is pinned at
`Level.NONE` for the same reason).

**Emby query conventions.** List endpoints request the narrowest `Fields` /
`EnableImageTypes` set that the row needs (`getHomeItems` enforces this); full metadata is
fetched only via `getItemDetails` after D-pad focus settles (140 ms debounce in
`HomeViewModel.focusItem`, with an LRU cache and cancellation of the in-flight job). Adding
fields to a home query is a startup-cost regression — extend the detail call instead.
Emby time values are 100-ns ticks; convert at the boundary (`millisecondsToTicks`,
`resumePositionMs`).

**A detail page is warmed while its card is focused, in two waves.** By the time somebody
presses a card, the item record, its "why you might enjoy it" and its playable URL have all
been fetched — and now so have its episode list and its trailer, which were the two things
the page still opened cold. That mattered most on Continue Watching, where every card is an
episode and pressing one opened a page with no season scroller and no episode list until the
network answered. Things to preserve:

- **The two waves have deliberately different delays.** The metadata warm follows the D-pad
  closely at `FOCUS_METADATA_DEBOUNCE_MS` (140 ms) because it decides what the panel beside
  the row says; `warmDetailPage` waits `DETAIL_PREFETCH_DELAY_MS` (450 ms) because an
  episode list is the largest request this client makes — a long-running show is a thousand
  records — and warming one per card as somebody scans a shelf would spend more than it
  saves. The job is cancelled when focus moves, so a viewer travelling along a row never
  reaches it and one who has stopped, which is what precedes a press, does.
- **Everything warmed on focus must be single-flighted on the repository's own scope**, for
  the reason `getRelated` already was: the warming job dies with the D-pad, and a request
  cancelled at the socket is one the gateway logs as a failure and one nobody keeps the
  answer of. `getSeriesEpisodes` and `getLocalTrailer` now take the same shape. A prefetch
  added without it makes navigation *slower*, because the press that follows re-asks.
- **`getLocalTrailer` caches its negative answer** (`CachedTrailer`, the `CachedTrickplay`
  precedent). Most of a library has no local trailer, so before this every detail page opened
  with a request the gateway answered 404 to, repeated on walking Back and again for every
  step of the "More like this" trail.
- **An episode is keyed on its series**, not on itself — that is what its own page will ask
  for, and it is what makes one warm serve a whole row of Continue Watching.

**A detail overlay seeds its settings from `repository.currentSettings`**, never
`Settings.EMPTY`. Collecting a flow with an empty initial value draws the first frame under
default preferences and then recomposes the entire page — and restarts the effects keyed on
those preferences, which is a second ratings request — one frame later, at exactly the moment
the page is trying to appear.

**Synced settings.** A viewer's settings live on the *server* and follow the person to
whichever television they sign into; an operator can also read and push them per user from
the admin console's accounts page. Three pieces:

- **The vocabulary is `internal/api/preferences.go`**, a `preferenceCatalogue` in the same
  shape as `featureCatalogue`, and it is the only place that decides what a legal value is.
  The admin console renders its editor straight from it (it rides along on
  `/admin/api/accounts`), so a new setting is one catalogue entry plus the matching key on
  the TV. The store holds the document opaquely — adding a setting is never a migration.
  `normalizePreferences` returns a *complete* document with unknown keys dropped and
  illegal values replaced, which is what stands between a hand-edited admin request and a
  launcher that cannot draw a row; it is the piece worth testing hard.
- **The revision is the delivery mechanism.** `user_preferences` carries one, `/v1/status`
  carries the current value, and `PreferencesSync` fetches the document only when it
  differs from what this TV holds. That is why an operator's push arrives within a poll
  without a second connection, and why the poll stays one integer for every open TV.
  Writes take an advisory lock and a revision check because every television in the house
  writes this row; a 409 returns the winner's document in the body, and the client
  **adopts rather than retries** — the other writer is usually the operator.
  `store.ForceRevision` is how the admin push deliberately wins that race.
- **`PreferencesSync.lastSynced` is what stops a feedback loop.** It records the document
  both ends agreed on, and a push happens only when the local state differs from *it* —
  so adopting a pull, which writes to DataStore and re-emits the settings flow, never
  looks like a local edit. Keep that invariant or the two ends will push each other
  forever.

**Every revision is kept, and the operator can put one back.** `user_preference_revisions`
holds the whole document per revision with who wrote it, written in the *same transaction*
as the document itself, so there is no state in which a revision exists and nothing records
where it came from. `internal/api/admin_preferences.go` serves it at
`/admin/accounts/{userID}/settings` — a hidden page, addressed by a route carrying the
person in the path like the account page it is reached from. Things to preserve:

- **A restore is a forward write, never a rewind.** It goes out as the *next* revision
  carrying an old document, with `restored_from` recording where it came from. The revision
  is the entire delivery mechanism — televisions compare numbers — so one that went
  backwards would leave every set in the house believing it was already up to date while
  holding what the operator had just replaced. It is also what makes a restore undoable:
  the version it replaced is still a row below it.
- **The restored document is re-normalised.** A revision written before a setting existed
  has nothing to say about it, and one written before its options changed may hold a value
  the server would now reject — restoring verbatim would put that on a television.
- **What a row *says* is `preferenceChanges`**, a pure function driven entirely by the
  catalogue, so a setting added tomorrow is described without touching it. It compares the
  rendered *labels* rather than the values: two documents that read identically have not
  changed anything an operator can see, and a television pushing back the document it
  already held is an ordinary event that must not fill the table with rows nobody made. The
  oldest revision held is labelled `initial` rather than diffed against the defaults, which
  would claim decisions nobody made.
- **`user_preference_acks` is the receipt the revision does not have.** The status poll
  tells every open TV the number; being told is not having adopted, so an ack is written
  when a set *fetches* the document (and when its own write is accepted, or its 409 hands
  it a winner it adopts). That is what separates "the bedroom TV never fetched it" from
  "it fetched it and something has since overwritten it". History and acks are pruned
  together at write time by `preferenceHistoryLimit`, except that a device's most recent
  ack is never pruned — a set switched off for a year is exactly the one worth describing
  as "on revision 12" rather than as one that has never checked in.

**Upgrading an existing install is schema 2** (`SettingsMigrationLogic`,
`CURRENT_SETTINGS_SCHEMA`). Nothing is lost: the flat keys already hold every value and are
what the app renders from, so a viewer sees their settings unchanged on first launch, and
`preferencesRevision` starts at 0 — which means the first sync *pushes* what the TV has
rather than pulling defaults down over it. The one thing that needed a migration step is
the three toggles that moved from device-wide to per-profile: an existing install has them
in the flat keys and in no profile, so they decode as the defaults, and the first profile
switch would have copied those defaults back over the flat keys (`applyProfile` writes
profile → flat) and then synced the result up as a deliberate choice. Step 1→2 folds the
device-wide value into every stored profile, which is exact rather than approximate —
while it was device-wide, that value really was in force for all of them. It cannot detect
its own work (the encoder omits default values, so a profile that chose `true` is
byte-identical to one that never chose), so the schema version is the only thing making it
run once; a test pins that.

What syncs is a person's choices; what does not is anything identifying a *television* —
device name, update source and token, the screensaver's rotation and ring colour.
`showTitleLogo` / `autoPlayNextEpisode` / `showTenMinuteReminder` moved from device-wide to
per-profile as part of this, because a device-wide value would push whoever signed in last
into everyone else's account. `SettingsStore.applyRemotePreferences` writes all nineteen
keys and the revision in **one** edit — DataStore rewrites the whole file per edit, and the
revision landing apart from the values it describes would leave a TV permanently believing
it was up to date while holding something else.

**Multi-profile session state.** `SettingsStore` stores a list of `EmbyProfile` (server,
token, userId) *and* mirrors the active profile into the flat top-level keys the rest of
the app reads. `switchProfile`/`saveSession` must keep both in sync; `legacyProfile()`
synthesises a profile from the flat keys for installs that predate the list. `deviceId` is
intentionally preserved across `clearSession()`.

**`deviceId` is the television's identity**, in Emby's devices list and in Settings →
Devices alike: the gateway holds one session per `(user, device_id)` and Emby keys its own
device record on the same value, so a set that signs in with an id either list has seen
replaces its entry rather than adding one. It therefore has to outlive the app's own
storage, which on these sets it does not — every APK is sideloaded, an install that will
not go over the old one is done by hand as an uninstall and reinstall, and the DataStore's
`ReplaceFileCorruptionHandler` empties the file after a process killed mid-write. So
`deviceIdFor` derives it from `ANDROID_ID` (hashed, so the platform id is never sent
anywhere) rather than generating a UUID, and falls back to a random id only for the values
that identify nothing — null, blank, all zeroes, or the one a batch of early devices
shared, where two televisions would otherwise become one. An id already stored is kept:
changing it is the duplicate this avoids, which is why installs predating this keep theirs
and converge only when they are next reinstalled.

Removing a device is two deletions, not one. `handleDeleteDevice` (and the admin console's
equivalent) revokes the gateway session and then calls `retireEmbyDevice`, because logging
out only invalidates the token — Emby keeps the device row in its dashboard until the row
itself is deleted, so a TV removed from one list would stay visible in the other. It is
best-effort on purpose: the session is already gone, which is what ends that TV's access,
and it needs the sync credentials since the record belongs to the server rather than to
the viewer.

**A television that changes its device id supersedes its old one.** Sessions are unique per
`(user, device_id)`, so a second row for one set can only mean the id itself moved — a
reinstall on a build that generated a random one, or an install predating the derived id.
Left alone each of those keeps a session row, an Emby device record and a build history of
its own, and one set in a living room reads as three. `store.supersedeDevices` runs inside
`CreateSession`'s transaction, deletes the same user's other rows carrying the same device
*name*, and hands them back so `retireSupersededDevices` can take the cached session, the
build history and the Emby record with them. Two things hold it up: the match is on the
name because it is the only evidence there is — the token, the session and the Emby record
are all new — and `supersedeName` (pure, tested) refuses a blank name and
`store.DefaultDeviceName`, the compatibility placeholder an unnamed build sends, or the
second unnamed set in a household would sign the first out on every launch. It happens
after the sign-in has succeeded, because tidying a set's previous life must never be what
stops it getting in.

**Build history is per device id, not per session** (`device_versions`). A session row
carries only the version in force right now and is overwritten by the next call reporting a
different one, so on its own "what has this set been running" is one value deep. It is
written from two places and needs both: `handleLogin` for a fresh sign-in, and
`captureClientIdentity` for a set that updated *itself* and will therefore never sign in
again — guarded there on the version actually having moved, since every authenticated
request reaches that path. It is keyed on the device rather than the viewer because the
history belongs to the television, and it is deleted wherever a device row is.

The profiles blob deliberately does **not** carry cached home JSON. Preferences DataStore
rewrites and fsyncs the whole file on every edit, so embedding a several-hundred-KB cache
per profile meant every settings toggle rewrote all of them. `writeProfiles` is the single
writer and strips the field out into a per-profile `home_cache::<userId>@<serverUrl>` key,
which doubles as the migration for installs that still embed one — `applyProfile` reads
the dedicated key and falls back to the embedded copy. Add a profiles write and it must go
through `writeProfiles`.

That per-profile key is also the **read** path (`activeHomeCache`), and the only place the
cache is written. The flat `home_cache` key remains only for a store with no active profile
to key against, and for installs written before the split. It briefly held a second copy of
every cache alongside the per-profile one, which put the largest value in the store into the
file twice — on a format that rewrites and fsyncs the whole file per edit, and on a value
rewritten by every home refresh.

**Home startup path.** `HomeCache` (last successful home response) is persisted per profile
and used as the initial `HomeUiState`, so the launcher renders rows before the network
returns; sections then refresh in parallel under a `Mutex` and re-persist. Playback stops
are broadcast through `repository.playbackStops` and refresh only the Continue/Next-Up rows.
Three things protect that "before the network returns" promise, and all three are easy to
undo by accident:

- **Nothing on the signed-in path may block on a request.** `AppRoot` used to hold the
  launcher on the loading screen until `getRecommendationOnboarding()` answered, which on a
  slow connection meant the cached rows could not be drawn until the connect timeout
  expired. Onboarding completion is now persisted (`Settings.hasCompletedOnboarding`,
  `markOnboardingCompleted`) and consulted first; the gateway is still asked in the
  background and stays authoritative for anyone not yet recorded. For a profile with no
  record yet the ask is still on the critical path, so it is bounded by
  `ONBOARDING_CHECK_TIMEOUT_MS` and fails open to the launcher — and only a verdict the
  gateway actually returned is persisted, or a single slow response would retire the rating
  screen for someone who has never seen it. The `onboardingToken` guard that stops repeat
  asks must always be paired with a null check on the verdict itself: on its own it can
  match a restarted effect's own token and strand the launcher on the loading screen
  permanently.
- **The settings flow must never be able to terminate.** It is the gate everything waits
  behind, and a `shareIn`ed flow that completes exceptionally never emits again — so a
  single failed read shows up as "Opening Memby…" forever, surviving relaunch. Hence the
  `ReplaceFileCorruptionHandler` on the DataStore and the `catch` before `shareIn`. Do not
  remove either: this store is rewritten on every home refresh, so a process killed
  mid-write is an ordinary event on a TV.
- **The cache is decoded off the main thread.** `SettingsStore.primeHomeCache` parses it on
  the store's IO scope as the settings flow emits, and `homeCache()` returns that memoized
  copy — `HomeViewModel`'s constructor runs during composition, so decoding there parsed
  the whole blob on the main thread at exactly the wrong moment.
- **`setHomeCache` skips unchanged writes** (`lastPersistedHomeCache`). It runs on every
  refresh *and* every playback stop, and most passes find nothing new.

**Screensaver hosting.** `ScreensaverContent` is shared by `MembyDreamService` and
`ScreensaverActivity`. A `DreamService` is not a `ComponentActivity`, so
`DreamLifecycleOwner` supplies the ViewTree lifecycle/ViewModelStore/SavedState owners
Compose requires; D-pad handling lives in the composable while the hardware Play/Pause key
is intercepted in `dispatchKeyEvent` and routed via the `ScreensaverActions` holder.
Playback from the dream `finish()`es first and starts `PlayerActivity` on a delayed main-
thread post to avoid the "activity behind the dream" race.

**In-app updates.** `UpdateChecker` polls a **Gitea** release
(`/api/v1/repos/{owner}/{repo}/releases/latest`, token auth for private repos) or a static
manifest, downloads and verifies the APK, then commits it to a **`PackageInstaller`
session**. Because replacing the APK kills a running Dream and leaves a black surface,
`UpdateRecoveryReceiver` catches `MY_PACKAGE_REPLACED` and relaunches `MainActivity` with
`EXTRA_LAUNCH_UPDATED_SLIDESHOW`.

**There is no "check for updates" on the television.** Settings had an Updates page with that
button on it, and the address, repository and token it needs could not be entered anywhere on
this app — so the only thing it could ever report was a failure, on the one screen a viewer
opens when they already suspect something is wrong. The single answer about updates is the
gateway's (`server/internal/appupdate` → `ui/UpdateScreen.kt`), which arrives on every launch
and carries its own `downloadUrl`; `SettingsPage` has no `UPDATES` entry and the version this
TV is running is stated once, on About. The `updateBaseUrl`/`updateRepo`/`updateToken` keys
remain in `Settings` and nothing writes them — they are what an install predating this still
has in its DataStore.

The session is not an implementation detail — it is why the updater works on a television.
The phone idiom, an `ACTION_VIEW` intent at the APK's content URI, fails three ways here: the
implicit intent is subject to package visibility on Android 11+, several TV builds expose no
activity for the package-archive MIME type at all, and nothing reports what the installer
then did. Sets that hit it had to be reinstalled by hand to move a version. So:

- **`verifyApk` must distinguish "wrong key" from "could not read the key".** It compares
  the downloaded APK's signers against the installed app's, and the trap is that
  `getPackageArchiveInfo` leaves `signingInfo` null on several Android versions where
  `getPackageInfo` fills it in. Asking only for `GET_SIGNING_CERTIFICATES` therefore
  produced an empty set for the archive, which the check reported as *"not signed by
  Memby's trusted release key"* — on correctly signed APKs, every release, leaving a manual
  reinstall as the only way to move a version. So: both flags on both sides, prefer
  `apkContentsSigners` and fall back to `signatures`, and let `signerVerdict` (pure,
  unit-tested) return `UNVERIFIABLE` rather than `MISMATCH`. An unverifiable read proceeds:
  the APK has already been matched against the published SHA-256, package name and version,
  and Android enforces signature identity at install time regardless — a real mismatch comes
  back as `STATUS_FAILURE_CONFLICT` with a message saying to reinstall.
- **The outcome is a broadcast, not a return value.** `downloadAndInstall` succeeding means
  the session was *committed*; `InstallResultReceiver` receives what happened and publishes
  it on `AppInstall.messages`, which every screen that can start an install collects. A
  mandatory update is the reason this matters: the screen cannot be dismissed, so "Opening
  the installer…" with nothing following it is a dead end with no explanation.
  `installStatusMessage` is the pure wording rule and is unit-tested — a TV has no logcat
  and no support channel, so that sentence is the whole diagnosis.
- **`STATUS_PENDING_USER_ACTION` is the normal path, not a failure.** The system hands back
  an intent for its own confirmation screen and the receiver must launch it.
- **The permission is asked for during setup, not at update time.** Every TV here is
  sideloaded, in practice through Downloader — which means *Downloader* holds Android's
  per-app install permission and Memby never does. `ui/InstallPermissionScreen.kt` sits
  between `FirstRunScreen` and `SetupScreen` on a fresh install, and is deliberately
  **skippable**: a permission that only matters later must never block a new install, and on
  a TV with no permission screen there would be nothing the viewer could do to satisfy it.
  The numbered steps are the substance — Android's own screen is an unexplained list of app
  names with switches, reached by a remote.
- **The operator can push that step to TVs already in service**, which is the half that
  fixes the existing fleet rather than only new installs. It is an ordinary entry in the
  gateway's `featureCatalogue` (`install_permission_prompt`), so it rides the status poll
  and the admin console renders its toggle with no extra work. Three conditions guard it and
  all three matter: the client must declare `install_permission_v1` (an older app can never
  be sent a screen it does not have), the operator must have it on, and the permission must
  actually be missing — which is what makes it self-clearing, since granting it removes the
  only reason it appears. `MaintenanceMonitor.installPermissionPrompt` defaults to **false**:
  a missing field must not conjure a screen.
- **The permission dead end is stated, not retried.** Many TV builds do not implement
  `ACTION_MANAGE_UNKNOWN_APP_SOURCES`; when starting it fails, the message names the path
  through the TV's own settings instead. Before this the failure was swallowed and the
  screen promised to continue "when you return" from a screen that never opened.
- Stale sessions are abandoned before a new one is created (they hold a staged APK and count
  against the per-app limit), and `UPDATE_PACKAGES_WITHOUT_USER_ACTION` lets later updates
  apply silently once Memby is its own installer of record — never depended on, since the
  system falls back to asking.

**Playback** uses Emby's direct stream (`/Videos/{id}/stream?static=true`) — no
`PlaybackInfo`/transcode negotiation, so exotic codecs may fail. The
`media3-exoplayer-hls` dependency is already present for when that's added. Progress is
reported back to Emby via `reportPlaybackStarted/Progress/Stopped`.

**Which subtitle comes on is the gateway's decision**, not the television's. The server is
what calls `PlaybackInfo` and enumerates the streams, so `selectSubtitle` in
`internal/api/subtitles.go` picks one from the viewer's synced settings
(`subtitlesEnabled`, `subtitleLanguage`) and `/v1/items/{id}/playback` and `/next` return it
as `selectedSubtitleId`. Turning subtitles off, or choosing Italian, in the player's overlay
writes those two settings (`SettingsStore.setSubtitlePreference`), so the choice follows the
person to every set rather than staying in the room it was made in. Things to preserve:

- **The rule exists twice on purpose.** `selectSubtitleId` in `data/SubtitleSupport.kt` is
  the direct path's copy, and the two are pinned by deliberately parallel tests
  (`SubtitlePreferenceTest`, `subtitles_test.go`) — with no gateway there is nobody to ask,
  and a viewer must not get different subtitles depending on whether the container is up.
  The language alias table is duplicated for the same reason: Emby writes three-letter codes,
  media3 reports two, and both ends have to agree on what "Italian" means.
- **A chosen language that the title does not have falls back to a *forced* track and
  nothing else.** Falling through to the default would put English on screen for somebody
  who asked for Italian; forced subtitles translate what is foreign to the film's own audio
  and are wanted either way.
- **`subtitlesEnabled: false` disables the text track explicitly.** Declining to select one
  is not enough — media3 turns on a default-flagged track by itself, so "off" has to be said.
- **`selectedSubtitleId` is matched on `Format.id`**, which is the id the sidecar's
  `SubtitleConfiguration` was built with. It can legitimately fail to match a container's
  embedded track, which is why `preferredTextTrack` falls back to running the same rule over
  the player's real tracks rather than giving up.

**A subtitle the library does not have is fetched from the player**, in
`internal/api/subtitle_download.go` over the provider layer in `subtitle_providers.go`.
**Two backends answer and they are not the same shape**, which is the one thing to hold on
to about this feature. **Bazarr** (`server/internal/bazarr`) writes the file *beside the
media file*, so the gateway stores nothing and serves nothing — it asks Bazarr to fetch,
calls `emby.RefreshItem` so Emby notices, waits `embyRefreshSettleDelay`, and re-reads the
streams; the new track then arrives down the ordinary `PlaybackInfo` path, which is why
`playableSubtitle` needed no new shape and `selectSubtitle` works on it with no special
case. **OpenSubtitles** (`server/internal/opensubtitles`) hands back *bytes*, and the
gateway has no reach into the media directory, so a file fetched there is stored in
`downloaded_subtitles` and served back as a sidecar from `/v1/subtitles/{file}`. That
difference is the entire reason the gateway now holds a subtitle at all, and it is
contained: `mergeSubtitleTracks` puts what the gateway holds beside Emby's tracks inside
`playbackSubtitles`, so a downloaded subtitle is an ordinary track on every later playback
rather than something that exists only in the response that produced it. Things to
preserve:

- **The operator's switches are `store.SubtitlePolicy`, not environment variables.** A
  provider is offered when the `subtitle_download` feature is on *and* it is configured
  *and* it is switched on — `subtitleSources`, one place. Bazarr's address stays an
  environment variable because it is a service the household runs; OpenSubtitles is an
  account, so its key and login live in that document and the console's Subtitles page can
  enter, replace or remove them without a redeployment. The store refuses to record
  OpenSubtitles as on with no key, so the console can never show a switch that does
  nothing. Nothing on that page ever returns a credential — only whether one is saved,
  the stance the MDBList page takes.
- **A candidate carries its `Source` and the download dispatches on it.** The two tokens
  are opaque in different ways and handing one to the other is a mistake nothing
  downstream could detect. Empty means Bazarr, because an app built before there was a
  second provider sends no source and all its rows came from one place.
- **The two providers make opposite trades on identity, which is the hard part.** Bazarr
  keys on the *arr's id (`radarrid`, Sonarr's `episodeid`) and Emby knows neither, so
  `bazarrMovieFor` / `bazarrSeriesFor` / `bazarrEpisodeFor` match by title, year and
  episode number. They are pure and tested hard because a mismatch writes one film's
  subtitle next to another. Episodes match on *numbers*, never titles — the two disagree
  often enough (translations, differently named two-parters) to reject correct matches —
  and season 0 is specials, a real season, not "no season". OpenSubtitles keys on an imdb
  or tmdb id, which Memby already holds because the library import asks Emby for
  `ProviderIds` so external ratings can be looked up, so there is **no guessing on that
  path at all**. An episode is searched by its series' id plus season and episode number
  whenever the episode carries no id of its own, since a show has one far more often than
  each of its episodes does.
- **`resolveSubtitleTarget` reads the item once and fails per provider.** A film Bazarr
  has never heard of may still have an imdb id, and a title with no provider id may still
  be in Bazarr's list; only both failing is a failure. `providerSubtitles` then searches
  both at once — a manual search is a live provider query measured in seconds — and a
  provider that fails is dropped rather than failing the search.
- **The provider row is opaque.** The token is provider-specific and must be handed back
  verbatim on the download call; it round-trips through the television untouched rather
  than living in a server-side cache, so a viewer reading the list by remote cannot have
  their choice expire underneath them.
- **A machine translation is offered, and says so.** It is a real answer and sometimes the
  only one, so `rankMergedCandidates` sinks it below everything a person wrote rather than
  hiding it, and `MachineOnly` is on the wire because it is the one property that changes
  whether a viewer wants the row at all. The provider is now *named* on a row, where the
  single-provider version deliberately did not name it: with two backends the same
  language appears twice and "which of these is which" is a question the row has to answer.
- **The exhausted-allowance case keeps its own wording** (`opensubtitles.QuotaError` →
  `subtitleFailureMessage` / `subtitleDownloadFailureMessage`). It is the only failure
  where pressing the button again is definitely not the answer, and a television has no
  log and no support channel — that sentence is the whole diagnosis.
- **A stored subtitle's id is derived, not random** (`storedSubtitleID`), so fetching the
  same language for the same title twice replaces the file rather than growing a second
  track a viewer has to tell apart by guessing. Its `gw:` prefix is what keeps it out of
  Emby's namespace, which is stream indices — plain numbers — because the player matches a
  track on the id it was handed.
- **The gateway sends a *path* for a subtitle it serves, never an address.** It does not
  reliably know its externally reachable name and the television does, because it is the
  thing talking to it. `EmbyRepository.resolveSubtitleUrls` puts the base and the `t=`
  token on it, exactly as `imageUrl` does for artwork and for the same reason: media3
  fetches a sidecar as a plain URL with none of Memby's headers attached. A URL that is
  already absolute is left alone, so it is safe over every playback response.
- **`subtitleDownloadAvailable` rides the playback response**, not `/v1/status`: the
  drop-up is the only thing that asks and it already holds that response, where the status
  poll is made by every open TV every ten seconds. The client default is **false** — a
  missing field must never conjure a row that leads to a request the backend cannot answer.
- **A title with no subtitles is told so, in the track section** (`SubtitleTracksState`).
  A list holding nothing but "Off" is indistinguishable from a menu that failed to load,
  and the row that could fix it sits below a rule under a heading the eye has no reason to
  travel to — so the notice goes under the SUBTITLES heading and the focus ring opens on
  the search row instead of on "Off", which is the state the viewer is already in. Where
  no provider can be asked it says that instead, once, rather than leaving somebody
  looking for an option that is not there. `SubtitleMenuScreenshotTest` covers both.
- **Client-side it is a second screen, not a third section.** The drop-up is 344dp by about
  a third of a 720p screen; stacking a track list, the size chips and search results
  squeezed the tracks to one visible row. `SubtitleDownloadState.expanded` swaps
  `player_subtitle_main_section` out, and Back steps out of the download half before it
  closes the menu — one press per level.
- **`subtitleRequestInFlight` is a flag, not `job?.isActive`.** `lifecycleScope` uses the
  immediate main dispatcher, so a coroutine body runs synchronously up to its first
  suspension — before `subtitleSearchJob =` has been assigned. Reading the job would see
  the previous one on exactly the redraw meant to disable the rows.
- **A download resets `subtitleAutoSelectionAttempted`.** The new track only exists in a
  freshly built media item; without the reset the sidecar is attached and nothing turns it
  on.

**Changing it mid-film is a drop-up**, `player_subtitle_overlay.xml`, anchored over the
subtitle button it opens from rather than the full-height panel it used to be. It sits on
somebody's film, so there is no scrim and the panel is near-black: the option under focus is
the only fill on it (accent green), the choice in force is a quiet grey plate with a green
label, and every other row has no background at all. The margins are measured off the
transport row — 44dp end, 112dp bottom to clear its 72dp strip and the controls' 28dp
padding — and the top margin is what caps the track list before its `ScrollView` (which
takes the overflow via `layout_weight`) starts scrolling instead of growing up the screen.
`bindSubtitleMenu` in `ui/player/SubtitleMenu.kt` fills it from plain
`SubtitleMenuEntry` lists so `SubtitleMenuScreenshotTest` can render the real menu with no
player, server or decoder → `build/screenshots/subtitles-menu/`; deciding *what* the entries
are stays in `PlayerActivity`, the only thing that can read media3's tracks. Only the first
open animates — redrawing after a choice would slide the menu again under someone still
working down it.

**Who is that? is a button, not a menu item.** The cast panel has its own `player_cast`
control beside the subtitle button in `memby_player_controls.xml`, because the question is
asked mid-scene and one that has to survive a dialog and four menu rows is one nobody asks
twice. It is deliberately *not* also in `showTrackMenu`'s list: one thing reachable two ways
is one thing whose two entry points drift apart. Things to preserve:

- **The panel is a fade, not a card.** `player_cast_scrim` carries it up from the bottom
  edge so the scene stays legible above the names — which is the reason somebody opened it.
  The 48dp side inset matches the transport row, so opening it does not shift the column the
  title and controls are read in.
- **The heading is the title, not the word "Cast".** The accent eyebrow above already says
  what the panel is; repeating the button just pressed costs the line that could confirm
  what is being watched.
- **Initials sit behind every portrait** (`castInitials`, pure and tested). Emby has no
  photo for a good part of a typical cast, and a row of identical grey rectangles says
  nothing about which name is which. They are behind rather than instead of the image, so
  nothing has to decide in advance whether artwork will arrive.
- **The focus ring is the `foreground`**, drawn over the artwork, and the portrait takes
  `duplicateParentState` because the *card* is what is focusable. A remote has no hover: the
  ring and the scale are the only thing saying which face is selected.
- `bindCastPanel` in `ui/player/CastPanel.kt` takes a `CastPanelState` and an injected image
  loader, so `CastPanelScreenshotTest` renders the real cards with no player, server or
  network → `build/screenshots/cast-panel/`. `loaded` is separate from an empty list because
  "still fetching" and "no cast recorded" are different things to be told.

**Time to first frame** is the number playback is judged by, and a *resume* is the worst
case: it is a seek, and a seek over HTTP is several more requests before a single frame is
decoded. Four things exist to hold it down, and each is easy to give back:

- **`ui/player/PlayerEngine.kt` builds the player**, apart from the activity, because
  construction is on the critical path of every launch. It pulls media bytes through
  `HttpStack` rather than media3's own HttpURLConnection client, so the header, index and
  offset requests a resume makes reuse one connection instead of repeating the handshake
  three times; and it enables constant-bitrate seeking, so a container with no usable seek
  table computes the offset instead of reading its way there. Both are borrowed from
  [Wholphin](https://github.com/damontecres/Wholphin), a Jellyfin TV client under the same
  GPL-2.0 licence.
- **`PlayerActivity.onCreate` is ordered as critical path then decoration**, with the
  comment saying so. Build the player, hand it the stream, *then* wire the overlays. This is
  safe because media3 posts its callbacks to the main thread and none can arrive until
  `onCreate` returns. The service-alert `ComposeView` mounts on the first call to
  `hidePlaybackLoading` and the cast lookup runs from `startPlaybackSession`: both used to
  run during `onCreate`, spending Compose's first composition and an Emby request at exactly
  the moment the decoder wanted the main thread and the connection pool.
- **A resume opens the player before the stream is resolved.** `PlaybackRequest` carries
  what the launcher already knew from the card, `PlayerActivity` resolves the stream while
  the activity, its layout and its decoder are starting, and `adoptPlayable` takes on
  whatever the server settled (for a series, which episode). A cold start deliberately still
  resolves first: its wait is already spent inside the pre-roll, which cannot begin until
  there is a stream playing behind it, and whether there is a pre-roll at all is part of the
  same answer. `MainActivity` keeps two states for this — `launchingItem` is the gate that
  stops a second Play press stacking a second player, `resolvingItem` is the loading screen
  and belongs only to the route that waits.
- **The two launch forms are two places a `Playable` has to be unpacked, and only one of
  them is obvious.** `adoptPlayable` handles the request form; on the URL form — the cold
  start, and *any* launch where `readyPlayableForLaunch` had a warm prefetch in hand — the
  intent is the only thing that will ever carry an answer, and a field with no
  `putExtra`/`getExtra` pair silently takes its default. That is how `trickplayAvailable`,
  `skipIntroAvailable` and `endCreditsAvailable` were all shipped switched off: each
  defaults to **false** on purpose, so the omission produced no error, no log line and no
  request — the gateway saw zero `/trickplay` and zero `/intro` calls across seventy-seven
  playbacks. A new "is it worth asking the backend" boolean must be added in **four**
  places: the `Playable`, the intent's parameter list, its `putExtra`, and `onCreate`'s
  `getBooleanExtra`. `subtitleDownloadAvailable` is the worked example of all four.
- **`ui/player/PlaybackTrace.kt` says where the time went.** "Playback is slow" is not
  actionable; `event=first_frame … activity=…(+…) player=… stream=… prepared=… ready=…
  first_frame=…` is. Marks are cumulative from the Play press, a repeated stage keeps the
  first time it was reached, and a stage that never happened is absent rather than zero.
  `PlaybackTraceSections.kt` names the same two spans for a systrace so `:benchmark` can
  measure what the log can only report — see "Benchmarks" below.

Measured on a Chromecast with Google TV against the NAS gateway, the shape is:
`prepare()` → first frame is **over 90%** of a resume, the stream negotiation is ~120 ms
and the app's own startup ~365 ms. Within that, the largest single term is **cold versus
warm connection to Emby** — the same file, same seek, was 4177 ms on the first playback of
a session and 2004 ms on the second. Artwork and API traffic go to the *gateway* host, so
the pool has nothing open to *Emby* when the first playback starts, and that first resume
pays DNS, TCP, TLS and Emby's file open. Pre-warming that connection is the open
opportunity. Two things that look like causes and are not: the subtitle auto-selection
costs 20–200 ms, not seconds, and the seek itself is about 900 ms.

**The local Memby preroll is prepared while Home is idle.** `PrerollPreloader` owns one
process-scoped ExoPlayer for `res/raw/emby_preroll.mp4`; `MembyApp` queues its first prepare
on the main queue's idle handler, so decoder construction and the local resource read never
sit in `Application.onCreate` or in front of launcher composition. When a fresh playback
requires the preroll, `PlayerActivity` borrows that player and shows it in the pre-roll video
frame while the requested title negotiates and prepares, paused at zero, behind the overlay.
Three details preserve the performance claim: the clip's actual duration owns the hand-off
rather than a stale configured estimate; the old paused-content-frame path remains the
failure fallback; and the preroll player is stopped and parked at hand-off so it releases its
hardware decoder while HEVC content plays. Returning to Home prepares the same instance again
in the next idle window rather than constructing one per title.

**The same clip plays behind the cold-start screen** (`ui/LaunchPreroll.kt`). It is the one
screen every launch shows and the clip was the one thing Memby owns that nobody ever saw
there. It borrows the *same* cached instance — no second decoder, no second copy of the
file — and hands it back on dispose, so the next playback still opens on a prepared player.
**It now gates the launcher**, which is the whole point of it: it was decoration, uncovered
whenever the app happened to be ready, and on a warm start that was a fraction of a second —
so the one thing Memby owns was in practice never seen. The clip plays once from the
beginning, its last frame is held for `LAUNCH_INTRO_HOLD_MS` (2s), and only then is the home
screen composed. Things to preserve: **it gates but it can never trap** — no player, a
decoder error, or no rendered frame within three seconds all report finished immediately,
and `LAUNCH_INTRO_MAX_MS` (9s, the clip's four plus the hold plus room for a weak box) is
`AppRoot`'s outer bound on top of that, because a viewer must never be held on a black
screen by a branding clip; **`LaunchIntro.played` is process-scoped, not saved**, so an
activity Android recreates behind somebody is not a second launch and a profile switch does
not replay it; the pulsing mark and the welcome line fade *out* under the clip and back in
if the app is still opening when it ends, since the waiting screen and a four-second sting
said two things at once; and it no longer loops — looping existed so a slow cold start never
froze on the last frame, which the hold and the fade-out do instead, and a clip that never
ends cannot gate anything. It is still muted, because it now runs on every single app open,
where the pre-roll before a programme is audible and must *end* — `PrerollPreloader.acquire`
/`recycle` normalise volume and repeat mode so a borrower cannot leave the next one wedged.
It is acquired **after** `withFrameNanos`, because a cold start has nothing cached and
constructing an ExoPlayer inside the first composition of the screen that must appear
immediately is the cost the idle-handler prepare exists to avoid. And
`AppRoot` calls `MembyLoadingScreen` from **one** call site: the three states meaning "still
opening" were three, and Compose identifies a composable by where it is called from, so
moving between them disposed the screen and rebuilt it — which now means returning and
re-borrowing the player twice during the busiest stretch of a launch.

**What it says while it is opening is `ui/WelcomeQuotes.kt`.** Twenty-five lines per tone
plus eight headlines, because this is the most-read copy in the app and five per tone meant
a household saw the same sentence roughly every fifth time they switched the set on.
`WelcomeQuotesTest` counts the distinct lines a pool yields: a pool that shrank back, or
gained a duplicate on a copy-paste, looks identical to one that did not. The headline is
kept apart from the quotes and is not keyed on the tone — it names what the app is *doing*,
and rerolling it when the settings flow arrives would change the line mid-launch.

**Next up / auto-advance.** 30 s before an episode ends, `PlayerActivity` slides up
`player_next_up_banner.xml` and rolls into the next episode when it reaches zero (Settings
→ Playback turns it off; `Settings.autoPlayNextEpisode`). Which episode that is comes from
`repository.nextEpisode`, dual-path like everything else: `/v1/items/{id}/next` on the
gateway, `Shows/{seriesId}/Episodes?AdjacentTo=` directly. Both rely on Emby returning
`[previous, current, next]` in running order, so it is the *position* of the current
episode that identifies the next one — never the length of the list, which shrinks at both
ends of a season (`episodeAfter` in `playback.go`, unit-tested). Three things are easy to
break: the countdown is driven off the playhead, not a timer of its own, so pausing holds
it and seeking backwards out of the window re-arms it; advancing swaps the `MediaItem`
inside the running player instead of relaunching the activity, so `itemId`/`playbackStarted`
/`stopReported` must all be reset together or the outgoing episode is never reported
stopped; and a movie simply resolves to null, which is why nothing special-cases item type.

**Skipping is Left and Right, and it does not open anything.** `ui/player/SeekControls.kt`
holds the arithmetic and the wording; `PlayerActivity.dispatchKeyEvent` owns the keys and
`player_seek_indicator.xml` is the centred chip that says what just happened. How far one
press moves is `Settings.seekIntervalSeconds` — 10, 20 or 30, a synced per-profile setting
like the subtitle ones, with the same vocabulary in `data/SeekPreference.kt` and in the
gateway's catalogue. Things to preserve:

- **A press moves a target, not the playhead.** `SeekPreview` accumulates and the seek is
  committed `SEEK_COMMIT_DELAY_MS` after the last press, because a seek over HTTP is
  several requests before a frame is decoded — four quick presses must be one seek of two
  minutes, not four the viewer sits through in turn. It also has to accumulate against the
  *previous target* rather than the live position, or the film running underneath swallows
  part of every press after the first.
- **The keys are only taken while the transport is hidden** (`seekControlsActive`, the
  same gate shape as `centrePausesPlayback`). With the controls up, Left and Right belong
  to whatever holds focus, and taking them would leave the subtitle and cast buttons
  unreachable. A stream that is not seekable falls through to media3 instead: nothing
  errors and nothing claims to have skipped.
- **Only discrete presses count.** A held key repeats at the platform's rate, which is fast
  enough to throw somebody minutes down a film they meant to nudge — the repeats are
  consumed rather than acted on, so letting go does not open the transport either.
- **A pending skip is committed in `onStop`** and dropped by `resetSeekControls` when the
  episode underneath changes, or the position reported to Emby — and so where the title
  resumes from — is one the viewer had already skipped past.
- **The buffering a skip causes belongs to the skip** (`seekBuffering`), so the loading
  overlay is withheld while the seek lands and the OSD is held up in its place — the viewer
  asked to move, and "+30s · 1:12:40" over their film is the answer to that where "Opening
  Memby…" reads as a failure. It also un-wedged the keys: `seekControlsActive` refuses to
  act while the overlay is up, so the overlay a skip raised swallowed the next press of the
  same key. Two bounds keep it honest — `showPlaybackLoading` clears the flag, so a retry,
  an error or the next episode is never withheld on a skip's account, and
  `SEEK_LOADING_GRACE_MS` puts the overlay up after all if the seek is still buffering
  6 seconds later, because past that it is not a skip landing, it is a film that stopped.

**And it shows the frame it will land on.** The idea and the shape are borrowed from
[Wholphin](https://github.com/damontecres/Wholphin), under the same GPL-2.0 licence, the
way `PlayerEngine`'s HTTP stack was; what differs is the format underneath. Jellyfin serves
tile sheets, so Wholphin crops a sub-image out of a grid. **Emby serves BIF files**
(`/Videos/{id}/index.bif?Width=320`): a 64-byte header, one 8-byte (timestamp, offset)
entry per frame plus a terminator, then the JPEGs laid end to end — 320×172 every ten
seconds, about five megabytes for a two-hour film.

The index sitting at the *front* of the file is the whole reason this is affordable on a
television. Read the first few kilobytes and every frame's byte range is known, so one
thumbnail costs a ranged request of about seven kilobytes rather than a download nobody
would wait through mid-seek. Things to preserve:

- **Trust the 206, not the headers.** Emby 4.10.0.21 answers ranges on that route properly
  and says so — a 206 with `Accept-Ranges: bytes` and a `Content-Range` naming the BIF's own
  length — but earlier builds were reported to serve the range while advertising
  `Accept-Ranges: none` and a `Content-Length` borrowed from the media file. So both
  `emby.TrickplayBytes` and `TrickplayClient` cap the read at what was asked for regardless,
  because being wrong about that must not turn a press of Right into a five-megabyte
  download.
- **A zero-frame BIF is an answer, not a fault.** Emby returns a perfectly well-formed
  72-byte file for a title whose thumbnails it has not generated, and for a width it does
  not hold — which is why `trickplayWidth` is not a free parameter and the client's
  `TRICKPLAY_WIDTH` must match it. The gateway caches that no for
  `trickplayMissingTTL` (shorter than the index's day, since thumbnails are generated on a
  schedule) or every press on such a title is a fresh round trip for the same answer.
- **The parsing exists twice**, in `data/Trickplay.kt` and `server/internal/trickplay`,
  pinned by deliberately parallel tests (`TrickplayTest`, `bif_test.go`) — the usual reason:
  with no gateway there is nobody to ask. What differs between the paths is *where the
  reading happens*, not what is read. In gateway mode the television holds no Emby
  credential, so the gateway reads the file and serves a frame at a time from
  `/v1/items/{id}/trickplay/{n}.jpg`; on the direct path the TV range-reads Emby's file
  itself. `Trickplay.bif` being null is what distinguishes them.
- **The manifest is its own request, deliberately not a field on `/v1/items/{id}/playback`.**
  Reading the index costs the gateway a round trip to Emby, and that response is the one
  thing standing between a Play press and a decoder starting. Only the boolean
  `trickplayAvailable` rides there — the `subtitleDownloadAvailable` precedent — so an older
  or deliberately-configured-off gateway is never asked. It is fetched from
  `startPlaybackSession`, beside `loadCast()`, for the same reason that one is.
- **Nothing about it may be on the path of a press.** The chip has always said where the
  skip lands and still says it with no thumbnail: a title with no previews, a server that
  will not answer and the moment before the first frame arrives are all the same wordless
  chip, which is what `SeekIndicatorScreenshotTest`'s empty case exists to hold. Every
  failure is silent, and `handleTrickplay` answers trouble with "no previews" rather than an
  error nobody could act on and everybody would log once per press.
- **Cancelling the in-flight frame is load-bearing**, the same property `collectLatest` gives
  search: presses arrive faster than a fetch completes, and without it a slow response for a
  frame already skipped past lands on screen after the one being waited for.
- **Scrubbing the transport shows them too**, not only the Left/Right chip. Those are the two
  ways to move through a film, and previews that stopped the moment somebody pressed a button
  to look at the controls read as the feature having broken rather than as a deliberate line.
  With the transport up the presses are the time bar's — `seekControlsActive` stands down —
  so `bindScrubPreview` hangs a `TimeBar.OnScrubListener` off `exo_progress` and draws into
  `player_scrub_preview`, a strip above the bar in the *controller* layout, which is what
  makes it disappear with the controls and need no visibility of its own. Things to preserve:
  it is the same `TrickplayPreview` instance as the chip, so one layout is fetched per title
  and one cache of frames serves both; it carries no wording, because the transport is already
  printing the position a caption would repeat; its horizontal place is computed from the
  scrubber in window coordinates and clamped to the bar, since a thumbnail parked mid-screen
  while the scrubber is at the far end is a picture of some other moment, and one pushed past
  the end is one overscan cuts; and it goes down on `onScrubStop` rather than on a timer, so
  it can never outlive the scrub that raised it.
- **The cache holds JPEG bytes, not bitmaps**, and is the player's own rather than Coil's.
  Decoded, forty frames would be most of a megabyte; as bytes they are a couple of hundred
  kilobytes, and decoding one costs a millisecond off the main thread. Keeping them out of
  Coil matters too — a burst of presses walks through dozens, and letting that churn through
  the artwork cache would evict the backdrops the launcher is about to want back.

**Skipping the opening titles is Emby's own answer, not a detector.** Emby finds intros
itself and writes them into an episode's chapter list as two markers, `IntroStart` and
`IntroEnd`, interleaved with the ordinary chapters in playback order — so there is nothing
to detect on either end and nothing to store: reading them is one `Fields=Chapters` lookup.
`introFromChapters` (`server/internal/api/intro.go`) and `introSegmentFrom`
(`data/Intro.kt`) are the pure rule, pinned by deliberately parallel tests (`intro_test.go`,
`IntroTest`) for the usual reason — with no gateway there is nobody to ask, and a skip must
not land somewhere different depending on whether the container is up. Things to preserve:

- **Most of the rule is about refusing to answer.** Half a pair, a pair out of order, a
  segment under 5 s or over 5 min all produce nothing, and nothing is a good answer: the
  player simply never offers the button. A wrong skip costs somebody the opening of a scene,
  which is far worse than not being offered one. The first `IntroStart` wins — two starts
  mean the markers are already untrustworthy, and the later one is the larger, more damaging
  skip.
- **The segment is its own request** (`/v1/items/{id}/intro`), the `trickplay` precedent:
  reading it costs a round trip to Emby and the playback response is the one thing standing
  between a Play press and a decoder starting. Only the boolean `skipIntroAvailable` rides
  there, and the client default is **false**. It is fetched from `startPlaybackSession`
  beside `loadCast()`, which is safe because the earliest intro in a typical library starts
  a couple of minutes in. "No intro" is cached (server and client) — most of a library has
  no markers, and without it the same no would be fetched on every playback.
- **`skipIntroMode` is a synced per-profile setting** (`prompt` / `auto` / `off`), with the
  vocabulary duplicated in `data/SkipIntroPreference.kt` and the gateway's catalogue like
  the seek interval's. It normalises to **`prompt`**, never `auto`: costing a set its button
  because it cannot read a value is recoverable, jumping through somebody's episode on a
  string this build cannot parse is not.
- **The ring counts the offer, not the title sequence.** `SkipIntroCountdownView` draws a
  draining arc with the figure inside it, advanced from the playhead by
  `updateSkipIntroCountdown` — so pausing during the titles holds it and seeking moves it,
  neither of which a wall-clock timer could do. It runs from where the button appears to
  where it goes, `SKIP_INTRO_TAIL_MS` short of the end of the intro. The two are seconds
  apart and only one can be drawn honestly: a ring measuring the whole sequence would stop
  with a sliver left and vanish mid-sweep, which reads as a broken countdown rather than as
  a lapsed offer. Three things to preserve — the view takes its colours from its own
  drawable state and the layout feeds it `duplicateParentState`, because the pill inverts to
  white on focus and a ring that did not follow would draw white on white; it refuses to
  redraw for movement under a degree, which over a two-minute opening is most of the ticks;
  and `formatRemaining` switches to `1:58` over a minute with the text sized from the
  string's length, since a title sequence is commonly long enough to be counted in minutes
  and "118" would print over its own arc.
- **The button takes focus and the notice does not.** A remote has no other way to say
  "press this", so it is focusable and `centrePausesPlayback` stands down while it is up —
  otherwise the one button on screen is unpressable. It never appears over the transport,
  the drop-up, the cast panel or the next-up banner, which already own the remote. An
  automatic skip instead swaps the same view into "Intro skipped" wearing the timing cues'
  quiet plate (`dressSkipIntro`), because a picture that jumps for no visible reason reads
  as the stream glitching, and a notice that still looks like a button gets pressed. The
  ring goes with it rather than freezing at zero: there is nothing left to press and nothing
  left to run out.
- **`skipIntroTaken` is never re-armed within an episode**, unlike `skipIntroDismissed`.
  Rewinding to before the titles offers the button again — somebody who went back there did
  it on purpose — but in automatic mode re-arming would drag them forward again the moment
  they reached the opening they had just returned for.
- **The seek goes through `seekBuffering`**, the same door a press of Right uses, so the
  couple of seconds it takes to decode at the new position is treated as a skip landing
  rather than as a film that has stopped.
- `SkipIntroScreenshotTest` renders it over a deliberately *bright* fake scene →
  `build/screenshots/skip-intro/`. There is no scrim under this button, so a capture over
  black would prove nothing.

**The closing credits are read out of the same chapter list as the intro.** `markersFor` in
`server/internal/api/intro.go` reads one `Fields=Chapters` response and answers for both
features, and `EmbyRepository.chapterMarkers` caches one reading that `introSegment` and
`creditsStartMs` both read. That is **the whole reason this is affordable** — adding a second
lookup anywhere in that path gives away the only performance claim the feature has. From the
result, `PlayerActivity` scales the picture into the left half, ramps it to 2× and puts what
is on next in the right half.

**Two sources, and the one it was built on does not exist.** `CreditsStart` is in Emby's
`MarkerType` enumeration, which is what this was originally written against — but a survey of
the 20,000-item library it ships to found `Chapter`, `IntroStart` and `IntroEnd` and **no
`CreditsStart` at all** on Emby 4.10. The enum having a value is not the detector populating
it. What that survey did find was 216 items carrying a chapter *named* like credits, clustered
at 90–98% of runtime and consistent within a show, and that is where every bit of the
feature's coverage comes from today (roughly 5% of items, but effectively all episodes of the
shows that have it). The marker is still read first, so the day a version writes one this
needs no change. Things to preserve:

- **The position floor is the load-bearing guard**
  (`creditsMinimumPositionFraction` / `CREDITS_MINIMUM_POSITION_FRACTION`, 0.75). Chapter
  names are not a vocabulary anybody agreed on, and real media carries **"Opening Credits"** —
  Belfast at 1% of runtime, Game of Thrones at 0%. A name match without a position test starts
  the pane in the *first minute* of a film and runs its opening at double speed, which is the
  worst thing this feature could do. Three quarters is deliberately far below the evidence
  rather than near it: every genuine roll in that survey began at 90% or later. The name
  exclusions beside it are belt-and-braces — a position test catches wordings nobody thought
  of, a word list only catches the listed ones.
- **The rule exists twice** — `creditsFromChapters` (Go) and `creditsStartFrom`
  (`data/Credits.kt`) — pinned by deliberately parallel tests carrying the real library's
  cases, the usual reason: with no gateway there is nobody to ask.
- **The two sources resolve in opposite directions, and that is not an inconsistency.** For a
  *marker*, the last wins (as the intro rule takes the first): two starts mean the markers are
  untrustworthy, so each rule picks whichever risks least, and the two features are damaged in
  opposite directions — an intro skip firing late throws somebody past the story, while the
  credits pane firing early runs the last scene past them at double speed. For a *name*, the
  earliest qualifying chapter wins: several credits-named chapters are ordinary rather than
  suspicious ("The Pitt" carries both "Credits" and "End Credits") and they describe one roll,
  which begins at the first of them.
- **A marker below the floor gives way to a name; with no runtime at all, the marker is
  honoured and the name is not.** An explicit marker is Emby asserting a position, so it gets
  the benefit of the doubt on wording — but not on position, and never enough to skip the one
  test that separates an opening sequence from a closing one.
- **`RunTimeTicks` rides the chapter lookup on both paths** for exactly that test. It is a
  default field on the response, so it costs nothing; do not drop it to tidy the query.
- **The duration guard is a second, separate refusal.** `creditsWorthShowing` asks whether
  enough of the roll is left to be worth moving the picture for (`CREDITS_MINIMUM_TAIL_MS`),
  and lives client-side because the player has the decoder's exact duration.
- **2× is a ceiling that falls, never a speed that is defended.** Doubling the speed doubles
  the bitrate pulled from Emby over HTTP, and a high-bitrate file on a remote server may not
  sustain it. `STATE_BUFFERING` calls `stepDownCreditsSpeed`, `creditsCeilingAfterStall` only
  ever goes down, and it is never re-armed inside one roll — a marginal stream that could
  climb back would oscillate between stuttering and recovering for the length of the credits.
  Reaching 1× leaves the pane up: what is on next is still worth showing, and only the
  speeding up failed.
- **It is the next-up banner's replacement, not a second thing beside it.** Both shrink the
  same picture and both say what is on next, so `updateNextUpFromPlayhead` returns early
  while the pane is up and the countdown moves into it — that countdown only appears inside
  the last minute, where it was always the banner's job. The pane also rides the banner's
  250 ms tick and its `nextEpisode` guard, which is exactly the right gate: a film and the
  last episode of a season both correctly get nothing. It therefore inherits auto-play's
  switch, since nothing resolves a next episode when that is off — deliberate, because this
  *is* the auto-advance experience.
- **The transform is a scale, never a reparent.** The pre-roll moves the `PlayerView` between
  parents; doing that mid-playback tears the SurfaceView down and flashes black over
  somebody's credits. `CREDITS_VIDEO_SCALE`/`CREDITS_VIDEO_SHIFT_X` are public so
  `EndCreditsScreenshotTest` can place its stand-in picture at exactly the transform the
  activity applies — a capture that guessed the split would prove nothing about whether the
  two halves balance, which is the only thing worth looking at. Neither is a round number:
  0.5 and 0.25 put the picture's left edge at exactly x=0, which is the first thing overscan
  cuts.
- **`speedUpCredits` is a synced per-profile toggle**, defaulting to **on** — a different
  trade from `skipIntroMode`'s, which defaults to the button rather than the automatic seek.
  This one is visible, reversible and over in a minute, so somebody who dislikes it turns it
  off having watched exactly what it does. `maskMarkers` withholds the half of a reading whose
  feature an operator has turned off, on the way *out* rather than on the way in, so the cache
  keeps the truth and a feature switched back on takes effect on the next playback.
- Screenshots are `EndCreditsScreenshotTest` → `build/screenshots/end-credits/`, over a
  deliberately bright frame: there is no scrim between the credits and the panel.

**Performance instrumentation.** `PerformanceMonitor` (JankStats) is debug-only and logs to
tag `EmbyClientPerf`. `benchmark/` is a `com.android.test` macrobenchmark module targeting
the release variants the `androidx.baselineprofile` plugin generates, so its numbers are
real rather than debug-influenced. `HomeBenchmark` deliberately measures cold start twice —
`CompilationMode.None()` and `Partial()` — because the only way to know the baseline
profile is earning its keep is to see both numbers.

`PlaybackBenchmark` measures time to first frame off the `Memby.playback*` trace spans,
with `resumeFromContinueWatching` and `coldStartFromHomeHero` as a pair — a resume differs
from a cold start in one way that matters, so it takes both to say whether a change helped
seeking or helped everything. Unlike the rest of the module it **needs a signed-in TV and a
reachable Emby**, since most of what it measures is network and decoder; its numbers only
compare against other runs on the same TV, server and title. It exists because a handful of
hand-timed launches could not settle anything — identical runs of one file varied by 70%.
Things to preserve: browsing happens in `setupBlock` so only the Play press is timed;
`openResumableDetailPage` *searches* the Continue Watching row for a Resume button rather
than assuming a position, because the row reorders as the household watches, and skips the
run rather than silently measuring a cold start and calling it a resume. The section names
are duplicated between `PlaybackTraceSections` and the benchmark because a `com.android.test`
module cannot link against the app — `PlaybackTraceNamesTest` is what stops a rename turning
the benchmark into one that finds no slices and cheerfully reports zero.

Two task names to get right, both of which fail confusingly rather than obviously. To check
it compiles use `:benchmark:compileBenchmarkReleaseKotlin` — `:benchmark:assemble` triggers
baseline-profile generation against a connected device. To *run* a benchmark use
`:benchmark:connectedBenchmarkReleaseAndroidTest`, not `connectedCheck`, which also runs the
`nonMinifiedRelease` variant and measures everything a second time. And `JAVA_HOME` must
point at the JBR, as for any direct Gradle invocation here.

**Release builds are minified.** `isMinifyEnabled`/`isShrinkResources` are on, which takes
the APK from ~14.9MB to ~3.1MB and the dex from 49MB across four files to 4.9MB in one —
no multidex, which matters because `minSdk` is 23. `proguard-rules.pro` is what keeps that
safe: it matches `@kotlinx.serialization.Serializable` on the *annotation* rather than
listing packages, because the previous rules named `com.mattcohen.embyscreensaver.data.model`
and had silently matched nothing since v0.1.53. Lint still has `abortOnError = false`, so
R8 warnings do not fail the build — check the task output after changing dependencies.

**R8 shrinks Kotlin; nothing shrinks a `.so`.** The APK is dominated by whatever native
code it carries, and native code is packaged **uncompressed** here (`minSdk` 23 means
`extractNativeLibs=false`), once per ABI. `io.github.abdallahmehiz:mpv-android-lib` was
added in v0.2.40 as a last-resort software video fallback and took the release APK from
3.1MB to **168MB**: a whole FFmpeg, `libc++_shared` and a 6MB subtitle font, times four
ABIs, for a path almost nobody ever reaches. It has been removed, along with
`MpvFallbackActivity`, `shouldUseLibmpvFallback` and the `is.xyz.mpv` keep rule. Two things
came out of it and both are cheap to keep:

- **`defaultConfig.ndk.abiFilters` is `arm64-v8a` + `armeabi-v7a`.** Android TV is ARM; the
  x86 slices only ever served the emulator, which is not how this app is tested.
- **A new native dependency is a size decision, not a dependency decision.** Check what it
  weighs across both ABIs before adding it — the Jellyfin FFmpeg *audio* decoder that
  actually delivers DTS is 1.5MB per ABI because it links only the decoders it needs, which
  is the shape to look for. Anything on mpv's scale belongs behind a separately downloaded
  split, not in the base APK that every television sideloads on every update.

**Baseline profile.** `androidx.profileinstaller` plus a profile generated by
`benchmark/BaselineProfileGenerator.kt`. Regenerate against a real television with
`.\gradlew.bat :app:generateReleaseBaselineProfile`; the result is checked in under
`app/src/release/generated/baselineProfiles`, so an ordinary `assembleRelease` needs no
device. A stale profile is not harmful, only progressively less useful.

**One HTTP stack.** `data/remote/HttpStack.kt` owns the single `OkHttpClient` that the
Emby API, the gateway API, Coil's artwork loader and the video stream itself all derive
from with `newBuilder()`, so they share one connection pool and dispatcher. This matters
most for artwork: in gateway mode the images are proxied by the same HTTPS host that serves
`/v1/home`, so a separate client would repeat the TLS handshake for every poster. It
matters again for a resume, which opens the same file three times over before the first
frame. Don't construct a bare `OkHttpClient.Builder()` — derive from `HttpStack.base`. The
stream's derived client raises the read timeout and sets **no call timeout**, which would
cap the length of a film.

## Language

**Everything a person reads is New Zealand English.** No American spellings: `-ise`/
`-isation` (personalise, synchronisation, organise), `-our` (colour, favourite, behaviour),
`-re` (centre, theatre), **licence** the noun and *license* the verb, **programme** for a
broadcast, and grey, catalogue, cancelled, labelled, travelling. This covers on-screen copy
in Kotlin and `res/values/strings.xml`, `CHANGELOG.md` (which the TV renders twice — Settings
→ About and the what's-new panel), the admin console, the release landing page in
`dist/template/`, every string the gateway sends the client to display (row titles, alert
`label`s, the preference and feature catalogues, error messages), and this repository's own
prose and comments.

**It does not apply to identifiers or anything on a wire.** Emby's API is American
(`favorites`, `IsFavorite`), so are Android and Compose (`Color`, `fontSize`,
`TheaterComedy`, `RecognizerIntent`), Go and Kotlin (`synchronized`, and the literal
`"request canceled"` in `images.go`, which matches `net/http`'s own error text), SPDX and
GPL names ("GNU General Public License"), and CSS. Renaming any of those breaks the wire or
the build. The rule is about words a person reads, never tokens a machine matches.

The boundary sits at the render, and the favourites row is the worked example: its id and
`kind` stay `favorites` on both sides, `personalisedFavouritesTitle` puts **"Favourites"** on
the screen. When a new string is both, spell the display half and leave the key alone.

## UI conventions

Use `androidx.tv.material3` components (`Button`, `Card`, `Text`) rather than the phone
Material 3 ones. `MainActivity.kt`, `HomeComponents.kt` and `ScreensaverContent.kt` are the
three large files — new screens generally belong in `ui/<feature>/` rather than growing
them further. Focus handling is explicit (`FocusRequester`, `focusRestorer`, `focusGroup`);
everything must be reachable by D-pad only.

**A keyed lazy list must never be handed a repeated key.** `LazyRow`/`LazyColumn` throw on
one — *"Key … was already used"* — and every list on these screens is keyed by an id that
came off a wire, where nothing promises distinctness. Emby lists the same person twice on a
good fraction of a real cast; a "Because you watched" row built from two seeds can reach one
title by both; a search that falls back to Emby before the import finishes can return what
the library also matched; and a paging boundary is where a backend repeats a card by
definition. `ui/ListKeys.kt` is the one rule: **deduplicate, never disambiguate.** Folding
the index into the key would also stop the crash, but it keys an item by *where it is*, and
position is exactly what changes when a row reorders — which the return-focus and
scroll-restoration behaviour throughout this app depends on identity to survive. Apply it
where the data enters state (`HomeViewModel.sanitisedRows`, `EmbyRepository.loadRelated` and
`loadSeriesEpisodes`, the two genre pagers, `SearchViewModel.runSearch`) rather than in a
composable; where a composable is the only place, keep it inside a `remember(list)`. And
where a pager deduplicates, **how far it has read is counted in what the backend sent**, not
in the length of the list (`SearchUiState.genreOffset`, `GenreBrowseUiState.readOffset`) — a
dropped duplicate would otherwise make the next offset point before the end of the last
page, and the shelf would stop growing while re-requesting the same page for ever.

**Animations must not recompose.** This app ships to weak TV boxes, so an animated value
read in a composable body — `val x by animateFloat(...)` then using `x` in the layout — is
a bug: it recomposes that whole scope every frame. Pass the value down as a lambda and
read it inside a `Canvas`/`drawBehind` block (draw phase only), and derive any text from it
with `derivedStateOf` so it recomposes when the *displayed* value changes, not when the
float does. `ServiceAlertBanner`'s countdown ring and pulse are the worked example: ~10
recompositions of one number over ten seconds instead of ~600 of the whole bar. The same
rule applies to collecting flows — collect in the smallest composable that needs the value,
not at the top of `MainActivity`, or every emission recomposes the launcher.

**Where a composable is too large to split, narrow the state instead.** `HomeScreen` is
the case: it cannot reasonably collect `HomeUiState` in one place, because reading the
whole object there meant an arriving update verdict, a slow-connection banner or any one
of the four section loads invalidated the launcher *and* rebuilt every row with it. So
`HomeViewModel` exposes three `distinctUntilChanged` projections — `content` (rows and
their loading flags), `status` (connection health) and `appUpdate` — and the screen
subscribes to each where it is rendered. `contentSlice()` blanks the non-row fields rather
than introducing a separate type, which is what lets `homeRowsFor` keep taking a
`HomeUiState` and the tests that pin it keep working; read only rows and `loading` from it.

**Design tokens.** `ui/theme/DesignTokens.kt` is the one vocabulary both surfaces read:
`MembySurface` (the near-black), `MembyAccent`, `MembyOnSurface`/`MembyMutedText`/
`MembyQuietText`, `MembyRatingsSurface` behind the ratings strip, three corner radii
(`MembyChipCorner` 8dp, `MembyCardCorner` 10dp, `MembyPanelCorner` 14dp), and the two
separators — `FactSeparator` between facts, `ValueSeparator` inside a fact that holds a
list. `HomeComponents`' `EmbyGreen`/`MutedText`/`QuietText` and `DetailPageComponents`'
`Detail*` colours are aliases of these; they had drifted into four near-blacks, four greens
and two secondary greys, which is visible the moment a detail page opens from a row. A new
colour or radius belongs in the token file, or is a considered exception — not a fifth
value.

**The eight slots a theme sends are not the vocabulary the screens paint with**, which is
why picking a colour scheme used to change almost nothing outside the detail pages. The
launcher, the cold-start screen, Settings, Search, the update and maintenance screens and
the two overlays were drawn with a hundred-odd literal hexes — a lighter green for a label,
a near-black ink for text on a green fill, three neutral steps for controls — none of which
the palette could reach. Those shades are now *derived* in `DesignTokens.kt`
(`MembyAccentBright`, `MembyAccentInk`, `MembyAccentMuted`, `MembyControlSurface`,
`MembyControlSurfaceRaised`, `MembyOutline`, `MembyDisabledText`, `MembySplashTint`).
Derived rather than added to the wire on purpose: a theme sends the *decisions* and the app
works out the shades around them, so a scheme invented on the gateway tomorrow arrives
complete rather than half-applied — the same reason the palette carries no radii. What
stays a literal is anything carrying meaning of its own: the red/amber/blue status colours,
the genre tiles, and the ratings providers' own brand colours. And a screen-local alias must
be `get()`, never `val` — `SettingsSheet`'s `Canvas`/`Panel`/`TextPrimary` were values, so
the settings page, which is where the theme is *chosen*, was the one screen that could never
repaint.

**Those colours are the server's answer, not constants.** Every token in `DesignTokens.kt`
is now a `get()` over one process-wide `mutableStateOf(MembyPalette)`, and `applyMembyPalette`
is what repaints the app. Two things follow and both are easy to undo: an alias must be a
getter too (`HomeComponents`' `EmbyGreen`, `DetailPageComponents`' `Detail*`, the settings
sheet's own `EmbyGreen`), because a `val` captures whichever theme was loaded when its class
initialised and never changes again; and `MembyTheme` builds its `darkColorScheme` per
composition rather than holding one, which is how a theme change reaches every component
that never names a colour. Shape and punctuation are deliberately *not* themeable — a
palette that could move a corner radius could make a layout wrong from the server, and the
whole safety of this feature is that the worst a bad theme does is look bad.

**The colour-scheme picker is currently withheld from Settings** —
`THEME_PICKER_ENABLED` in `ui/settings/SettingsSheet.kt`, one `const val` to put back.
Choosing a scheme does not reliably repaint the app, and a control that appears to do
nothing is read as a fault in the television rather than as an unfinished feature.
Everything below is otherwise untouched: seasonal themes still arrive and still apply, the
synced `themeId` preference is still carried, and the palette plumbing is unchanged. This
hides the question, not the answer.

**Themes** are `server/internal/api/themes.go`, and there are two kinds. A **selectable**
theme is the viewer's own choice, held as the ordinary synced preference `themeId` and
picked in Settings → Appearance. A **seasonal** theme (Halloween, Christmas, Easter) is not
a choice at all: it is in force for its dates and nothing on the television can decline it,
because a per-person opt-out is a thing somebody turns off in October and never reconsiders,
which is the same as the feature not existing. The only switch is the operator's
`seasonal_themes` feature flag, for the whole house. Things to preserve:

- **`resolveTheme` is the whole rule and it is pure**: a season outranks the viewer, the
  viewer outranks the default, and the operator's per-user allowlist narrows the *choice* but
  never a season. There is no argument a television can send that suppresses one, which is
  what "cannot be controlled by the user" means in code. The viewer's own pick is still
  reported as `chosen` underneath a season, or the picker would show nothing selected for a
  fortnight and read as having forgotten it.
- **The two windows resolve their edges deliberately.** Halloween opens on 25 October (a
  theme nobody sees until the evening of the 31st is one nobody sees) and Christmas closes on
  Boxing Day (the tree is down; red-and-green on the 30th reads as a server nobody maintains).
  Easter is the anonymous Gregorian computus in `easterSunday` — computed, because a
  hard-coded table is a feature with an expiry date on it — over Good Friday to Easter Monday.
  `seasonalThemeFor` takes the time rather than reading the clock, so every edge is tested.
- **The revision is a hash of the resolved theme, not a counter.** There is no write to
  attach a counter to: nobody writes anything at midnight on 1 December, the answer simply
  becomes different. `/v1/status` carries `theme: {id, revision, locked, seasonal}` — the
  `preferencesRevision` precedent — and the TV fetches `/v1/theme` only when it moves. It
  rides the poll rather than the sign-in because that *is* the feature: a season has to reach
  a set that is already switched on.
- **The allowlist is `user_themes`, and absence is permissive.** No row exists for anybody
  until an operator restricts somebody, so an empty list means "unrestricted"; reading it the
  other way would empty every picker in the house on the day it shipped.
  `normalizeThemeAllowlist` stores "every box ticked" as the empty list for the same reason —
  they are the same decision — and drops seasonal ids, which are not grantable per person.
  It is a separate table from `user_preferences` because that document is the viewer's own
  choices and every television they own writes it; this is policy *about* them and only the
  console writes it.
- **The available list is per viewer and comes from the server.** `/v1/theme` sends only the
  themes that person may pick, so a withheld scheme is a row the television was never sent
  rather than a greyed one — the client has no catalogue of its own to fall back to, and the
  picker is simply not drawn when fewer than two arrive.
- **Nothing repaints from the local choice.** `setThemeId` writes the preference and stops;
  the palette arrives through `ThemeSync` when the gateway has resolved it. That is what makes
  a choice a season covers, or one the operator has since withdrawn, visibly not take effect
  rather than take effect and be yanked back a second later.
- **`ThemeSync` paints from the cached palette before any request**, the promise `HomeCache`
  makes about the rows, and clears the cache on a profile switch (a different person, a
  different scheme). The palette cache is device state; only `themeId` syncs.
- **There is no second copy of the rule on the direct path**, unlike subtitles, intros and
  Continue Watching. Those exist twice because the direct path would otherwise *behave*
  differently; here it behaves as it always did — the default palette. A television deciding
  from its own clock that it is Halloween, while the household's gateway has seasons switched
  off, would be the feature failing rather than degrading. `data/Themes.kt` is only hex
  parsing, and it refuses anything it cannot read so the app's own token stands in.
**Seasonal decorations** are `ui/seasonal/SeasonalDecorations.kt`: snow, bats or blossom
drifting over the launcher for the few days a season is on. A palette on its own is a thin
idea of Christmas — the colours change and nothing says why — and this is the half that
does. It is also the most expensive thing in the app, the only animation that runs
continuously while somebody is merely browsing, so:

- **Nothing about it recomposes.** One `Canvas`, one animated `State<Float>` never read in a
  composable body, every position derived arithmetically inside the draw lambda. A full field
  costs zero recompositions and one draw pass. The palette colours *are* read in composition,
  deliberately, so a theme change repaints this node.
- **A particle is `index` and `progress` and nothing else** — no array, no per-particle state
  to allocate or re-seed. `drawSeasonalField` is therefore a pure function of one number,
  which is what lets a screenshot capture an exact frame with no animation clock.
- **Every cycle count is a whole number**, so at the instant the driving value rolls 1 → 0
  the entire field is exactly where it was. Without that it visibly jumps once a minute.
  `decoration-snow-0.png` and `decoration-snow-100.png` must be identical; that is what they
  are for.
- **Placement is stratified, not hashed.** Each particle owns a slice of the axis and the
  hash only jitters within it. Twenty-six samples is far too few for a hash to look evenly
  spread — the first version put visible bands and a bare patch through the middle, and the
  eye finds a clump in a snowfield instantly.
- **The slug comes from the gateway** (`decoration` on the theme), never derived from the
  theme id: an operator turning `seasonal_decorations` off sends an empty one, and a set
  holding a cached Christmas palette must stop snowing. It is a *second* switch from
  `seasonal_themes` because the palette and the animation have quite different costs on a
  weak box. An unknown slug draws nothing.
- **Launcher only.** Not over playback — a film is the one thing nothing may drift across —
  and not over the settings sheet. It is a sibling of `HomeScreen` rather than inside it, so
  an arriving theme cannot invalidate the rows.
- **The platform's "remove animations" setting is honoured.** A season is deliberately not
  the viewer's to decline, but an accessibility choice is not a preference.
- **The alpha was tuned by looking, not reasoned about.** The layer sits over an opaque
  surface, so a flake occasionally lands on the Play button; at this value that reads as snow
  in front of the screen and a few points higher it reads as a rendering fault.
  `decoration-over-content.png` exists for exactly that judgement.

- **Screenshots are the only real test this feature has.** A unit test can check that a hex
  string parses; it cannot check whether Easter's pale accent is legible on its own
  near-black or whether Forest still has a hairline. `ThemeScreenshotTest` renders one series
  page under every palette → `build/screenshots/themes/`, deliberately one screen across nine
  themes rather than nine screens on one, so the images differ in nothing but colour. It
  composes once and repaints by assigning the palette, which is both the only thing
  `setContent` allows and the more honest picture — that is exactly what a set already
  showing the page does when a season begins. The palettes are a *fixture* copied from the
  catalogue, not a second copy of the rule: nothing derives a colour from it. It caught the
  chip row overflowing at six themes, which is why that row is a `FlowRow` where every other
  choice row on the page is a `Row`, and it is why the blossom is a five-petal flower — a
  single petal rendered as a grey seed, recognisable as *something falling* and nothing else.

**One button language.** `ui/MembyButtons.kt` — `MembyPlayButton` (focusable),
`MembyPlayChip` (the same surface as decoration inside an already-focusable parent, for the
home hero) and `MembyChoiceChip`. There were three: this one, a hand-rolled copy in the hero
with the same look and different metrics, and raw `androidx.tv.material3.Button`s with
glyphs typed into their labels ("▶  Resume", "✓ 30 min"), which picked up theme colours
nothing around them uses.

**Settings is black, flat, and says one thing once.** `ui/settings/SettingsSheet.kt` had four
stacked surfaces to show two switches — the page, the rail, a titled section card, and the
rows inside it — and the card's title repeated the page header, which repeated the rail item
already highlighted beside it. It is now a black canvas with the rail separated by a single
right-edge hairline, and `SettingsGroup` lays rows flat with `SettingDivider` between them:
no card, no icon chip, no section heading. `SettingsGroup(label = …)` exists only for a page
with genuinely two groups (About), and is a quiet caption rather than a second heading. Three
things to keep: the *controls* are untouched (`StatusToggle`, `SettingsChoiceChip`, the badge
pill) because they are what makes the screen read as Memby and they look better on black than
they did on a card; the row under focus is the only lit surface on the page, so nothing else
may grow a background; and everything shares a 16dp left inset — header, rows, dividers,
notices — because with the card gone that inset is the only thing holding the column
together. Copy is plain-language and second person ("Ten minutes left", "Hide films you have
seen"), not feature names.

**Up out of the top of a page returns to the page list.** Nothing sits above a pane's first
control, so that press did nothing at all on every page — and a remote that stops responding
is not read as a list that has run out. About is where it was reported, its pane being a
changelog long enough that walking back up it is the ordinary way to leave. The escape is an
`onKeyEvent` on the content column that makes the move the default handler would have made
and falls back to the rail only when it fails, so a page's own vertical navigation is
untouched: `focusProperties { up = … }` is inherited by every row and would take that
navigation away, and `exit` is never consulted when the search finds nothing anywhere, which
is the whole case. The rail item for the page being *drawn* carries a second requester for
it — the selection rather than the highlight, so a press arriving mid-settle still lands on
the page that is on screen. `SettingsRailFocusTest` pins both halves, the escape and the
navigation between rows it must not disturb.

**One runtime formatter, one 4K threshold.** `detail/DetailFacts.kt` owns `formatRuntime`,
`heroFacts`, `dynamicRangeLabel` and `UHD_MIN_WIDTH`; the home hero and the card metadata
call them rather than carrying private copies. That is why the hero and the card directly
beneath it agree on "2h 4m", and why `mediaBadges` and the spec row's `(4K)` suffix fire at
the same width.

**A score is only ever shown by the ratings strip.** Emby's `CommunityRating` used to be
drawn as a gold `★ 8.4` on the detail fact row, the home card metadata panel and the home
hero, beside the strip that was already showing IMDb and Rotten Tomatoes — two ratings in
one panel, one of which named no provider at all. The client no longer renders it anywhere
outside the screensaver (which has no strip), and `EmbyRepository.getRatings` no longer
falls back to it either: standing it in for a real source meant a card claiming a TMDb score
TMDb had never been asked for. A title MDBList cannot answer for now shows no strip, which
is the honest answer. Scores are formatted by the gateway alone (`formatRatingScore`), by
the scale they are measured on — a fractional scale always keeps its decimal, so IMDb 7
goes out as `7.0` rather than a bare `7` beside somebody else's `8.2`.

**Home rows all lead with the same header**: `HomeRowHeaderIcon` + `HomeRowHeaderIconGap`,
`HomeRowHeaderSpacing`. A header that skips the icon chip starts its title 38dp left of
every other row, and the launcher's row titles are read as one column.

**The home hero** (`ui/HomeMovieHero.kt`) is a featured card plus three minis, each a
`HomeHeroPick` — the item *and the row it was drawn from*. The caption used to be the card's
slot ("POPULAR", "NEW RELEASE", "TRENDING" by index) while the selection interleaves sources
and falls back to every movie in the response, so it routinely lied. Only the **minis** carry
that caption now: they have no fact line, so the label is the only reason the card gives,
where on the featured card it sat above a line already printing the year and cost the height
that broke the button — the featured card says why in a sentence instead (see below).

**Play is measured before the words.** The featured card is a fixed height, and a Column
gives each child what the ones before it left — so the chip, being last, was handed the
remainder after a two-line title and rendered as a green sliver with its label squeezed out.
Compressed, not clipped, which is why it read as malformed rather than missing. The text now
sits in a `weight(1f, fill = false)` child, and weighted children are measured from what is
left over: the spacer and the chip take their natural size first and the prose gives way.
Keep that inversion. The `titleLines == 1` rule that stands the synopsis down is still worth
having — it means the give usually costs nothing visible — but it is a tidiness, not the
guarantee. `HomeMovieHeroScreenshotTest` renders the wrapping-title case for exactly this.

**The hero is composed by the gateway** (`server/internal/api/hero.go`), because the three
things worth ranking it by are three things the television cannot see. **Radarr knows when a
film actually came out** — `digitalRelease` is the date the household could first have
watched it, where Emby's `PremiereDate` is the theatrical date when it is right at all and a
metadata agent's guess when it is not, so ranking "new releases" by it produced an order
with nothing to do with when anything became watchable. **Sonarr knows a premiere from an
ordinary episode**, so a new show or a returning season can lead where before a series could
only reach the hero as a random card off a shelf. And **the review scores are already
attached to the cards** by `decorateHomeRatings`, so a well-received release can outrank a
fresher one nobody liked at no cost. `rankHeroCandidates` is the pure rule
(`heroRecencyWeight`/`heroRatingWeight`, `hero_test.go`); `selectHomeHeroMovies`'s original
row-interleaving rule survives underneath as the **direct path's** hero and the fallback for
a gateway older than the feature, which is why `serverHeroPicks` is consulted first and
returns nothing rather than throwing. Things to preserve:

- **It asks Emby for nothing.** The movie candidates are the rows already assembled and
  their ratings are already attached, so the expensive half of the launcher is reused
  rather than repeated. The two *arr calendars it does read are cached for the day behind a
  shared lock, like the schedule rows' — one household pays one miss each per day — and the
  three lookups run concurrently, because this is the tail of a response every television
  in the house is waiting on.
- **Every card it produces is playable.** A premiere the household has not downloaded, a
  film Radarr is still waiting on, a synthetic schedule card — all are news for the schedule
  row, and a lead card that does nothing when pressed is worse than no lead card at all.
  `sonarrPremieres` requires `HasFile` *and* an Emby series id for exactly this.
- **A premiere is the first episode of a season**, S01E01 or S05E01 alike, and season 0 is
  specials rather than a premiere. One card per series, the newest season winning, or a show
  that premiered and returned inside one window appears twice.
- **An unrated title is not a bad title** (`heroUnratedScore`, deliberately mid-scale). On a
  household that has not configured MDBList that is every title, and burying them would
  empty the hero; `heroRatingOf` falls back to Emby's `CommunityRating`, which the client is
  still forbidden from *drawing* — ordering four cards by a score claims nothing to anybody,
  where printing it beside a provider's name that was never asked is a lie.
- **The captions and the reason are the gateway's wording** (`MembyHeroLabel`,
  `MembyHeroReason`), the `MembyAirLabel` precedent, so a kind of hero card invented
  tomorrow reads correctly on today's build. `labelTint` matches them as strings for the
  same reason, and an unknown one gets the neutral wash rather than nothing.
- **A label is a claim that has been earned**, and `heroReason` returns empty rather than
  inventing one — the captions this replaced were the card's *slot*, which is how a 2019
  film came to be announced as new.
- **The row is consumed, never drawn.** `serverHomeRows` drops `kind == "hero"`; without
  that the four featured titles print a second time as an unnamed row of posters directly
  beneath the hero they are already in. `supportsHomeHero` gates it at 0.2.27 for the same
  reason — an older television has no idea the kind is special. That floor is the version
  the feature shipped *in* rather than one after it, so a 0.2.27 build predating it would
  draw the duplicate row; moving the floor up is the fix if that ever bites.
- **The row is a draw from merit bands, re-made four times a day.** Ranking straight to the
  row's length was the original design, on the reasoning that the facts behind it change
  daily — and they do not: a digital release date does not move, a premiere aired when it
  aired, a score settles within a week, so the same two cards led the launcher for five days
  at a stretch. `rotateHeroCandidates` ranks a pool of `heroPoolLimit` instead, cuts it into
  as many bands as there are cards to send, and draws one from each by
  `heroVariationSeed(userID, heroRotationSlot(now, location))` — the `selectSeeds` shape, and
  for the same reason it is not a shuffle: merit still decides which *band* a title is in, so
  the best-reviewed release of the week can never land in the fourth slot, and variation only
  picks between titles the scorer could not separate. The slot is the household's local part
  of the day and carries the date, the seed is per viewer, and a pool with no spare
  candidates goes out in merit order untouched. Home is cached for a minute and rebuilt
  constantly behind it, which is why one slot must always yield the same draw.
  The rotation further down belongs to the direct path, which has no merit to rank by.

**The reason sits above the ratings strip**, and that order is load-bearing. The featured
card's text column is what gives way when a title wraps onto two lines, so whatever is last
in it is cut — with the reason below the strip, the one line explaining why this card leads
the launcher was silently dropped on exactly the long-titled films most likely to be leading
it. The scores are also on the detail page the card opens; the reason is nowhere else. It
takes the synopsis's place rather than adding a line, so preferring it can only make the
card shorter, and there is still no eyebrow above the title.

**The direct path's hero changes daily, at local midnight.** `selectHomeHeroMovies(rows, day)`
takes a count of local days and rotates the starting point of each candidate list; `MainActivity`
keys its `remember` on `rememberHomeHeroDay()`, which sleeps until the next local midnight
rather than polling. Three properties are load-bearing and unit-tested. It is a *rotation*,
not a shuffle: the server's ranking is still the order, so what it thinks is worth leading
with comes round again and yesterday's hero is one place down rather than somewhere
arbitrary. The same day always yields the same four cards — the launcher rebuilds on every
home refresh and focus change, and a hero that re-picked each time would churn under
someone walking past. And the day is *local*: "resets at midnight" means the viewer's
midnight, which is why the zone offset is a parameter to the pure `localEpochDay` /
`millisUntilNextLocalDay` rather than read inside them. `Math.floorDiv`/`floorMod` for longs
arrived in API 24 and this app ships to 23, so that arithmetic is written out by hand.

**Detail pages** are one editorial layout shared by movies and series: `DetailPageScaffold`
in `ui/DetailPageComponents.kt` over the pure vocabulary in `ui/detail/DetailFacts.kt`. It
is a full-bleed cinematic hero — backdrop under two scrims, logo or title, `heroFacts` line
(year · length · certificate) with the score and format badges trailing it, genres, three
lines of synopsis, one recommendation reason, then Play and the circular secondary actions —
with an uppercase tab strip on a hairline rule anchored under it and the tab's content
beginning below the fold. `MediaDetailContent` is the movie page, `SeriesDetailContent` the
series one; they differ only in which tabs they offer. The tabs are Overview, Episodes
(series only), More Like This and Cast & Details.

- **The page is a `LazyColumn` of exactly three items** — hero, tabs, content — and the hero
  owns the opening frame: while focus is in it the list is pinned to offset 0 (see
  `detailHeroScrollTarget` and the `snapshotFlow` beside it), because LazyColumn's own focus
  relocation would otherwise leave Play visible with the title scrolled off the top. Moving
  to the strip or the content releases the pin.
- **A pane never scrolls.** Every section is a tab and every tab fits its slot, so adding
  content means adding a tab: a page that scrolls *and* has tabs gives the D-pad two
  meanings for Down. The slot is `detailPaneHeight(viewportHeight)`, derived from the screen
  rather than fixed — it was a hard 250dp, and everything `technicalSpecs()` produces fell
  off the bottom of Cast & Details, which is the whole reason that tab exists. If a pane
  needs more than the budget, cut rows; do not add a scroller.
- **The strip keeps a safe-area inset.** `DetailFoldPeek` holds it off the bottom edge,
  where overscan was cutting the selection underline in half, and leaves the top of the pane
  showing beneath it. That peek and the chevron at the end of the strip are the only things
  on screen saying that Down reveals anything.
- **Focus is selection** in the tab strip. A remote has no hover, so a strip that highlights
  one tab while a different one stays open would need a second press to mean anything and
  would show content that contradicts the highlight.
- **The strip is decided by what the item is, never by what has loaded.**
  `detailTabs(isSeries)` returns a fixed list, and a section with nothing in it yet says so
  in its own pane. It used to offer only the sections that already had content, which meant
  a movie opened with one tab and grew two more when its detail record landed, moving the
  strip under the viewer's thumb. `detailTab(key, available)` still resolves a remembered
  key, but now only has to catch a key carried over from the other kind of item.
- **One `FocusRequester` per pane**, never one shared between them. `AnimatedContent` keeps
  the outgoing pane composed for its 80ms fade, so a requester attached by both the Overview
  and the Cast & Details pane is attached to two live nodes, and a Down press landing in that
  window can focus the pane that is disappearing.
- **Position is remembered per item** in `ui/detail/DetailPosition.kt` — tab, season, which
  band held focus, and both rails' scroll offsets — in a process-scoped, capped, LRU store
  outside the composition, because closing a detail overlay destroys `rememberSaveable` with
  it. `RestoreDetailFocus` focuses Play first (it exists on frame one, so the remote is live)
  and then restores the band, once, only if that band has something placed to land on.
  Deliberately not persisted: a TV switched on the next morning should open a show where the
  *show* is up to.
- Every `focusProperties { up/down/left/right = … }` target must be attached **on the
  current frame**. Season chips and episode cards do not exist while the episode request is
  in flight, on a one-season show, or on any tab but Episodes — pointing at their
  `FocusRequester` anyway throws the moment the viewer presses that direction.
  `SeriesDetailContent` resolves each target to `FocusRequester.Default` when its
  destination is off screen; keep that.
- **Moving between the three bands is stated as intent, not as one destination.** Hero →
  strip → pane is the page's whole navigation and it must never be dead, so the scaffold
  routes those presses through `Modifier.onVerticalNavigation` and `focusFirstAvailable`,
  which takes a *list* — the selected tab, then the band as a focus group, then the pane —
  and moves to the first that is actually placed. Down out of the hero is on the hero as a
  whole rather than on the row of buttons, because whatever in there holds focus the press
  means the same thing; a band with nothing in it yet (an episode page whose seasons have
  not arrived) is passed through rather than stopped at. Two things to keep. It is
  `onKeyEvent`, not the preview, so a control that means something of its own by Up or Down
  keeps it, and an unhandled press still falls through to Compose's own focus search. And
  the **content pane keeps `focusProperties { up = … }`** rather than a key handler: panes
  navigate vertically inside themselves and override that property where they do
  (`EpisodeCard` sets `up = FocusRequester.Default` on every card but the first), which a
  blanket handler would take away. The tab strip anchors that requester to the first tab
  when the selected one is not in the list, so the property always names something real.
- The backdrop is held under two gradients before any text is drawn. The reference is flat
  black and that flatness is most of why it reads as modern; the artwork is there for tone,
  not as a picture.
- A tab item is `Modifier.width(IntrinsicSize.Max)`. Without it the underline's
  `fillMaxWidth` claims the whole strip and pushes every later tab off the screen.
- The hero honours `Settings.showTitleLogo` and `useTextTitleForLogo` (`ui/TitleLogo.kt`,
  shared with the screensaver): transparent Emby logos are commonly black, and a black title
  treatment on this scrim is an invisible heading.
- **Why you might enjoy it** is the single accent line above the actions, from
  `GET /v1/items/{id}/related`. It comes from the same profile the home rows are built from
  (`recommend.Why`), so the page can only claim a taste the engine actually learned; a cold
  profile falls back to catalogue facts. Never focusable.
- **More Like This** is the same response's `items`, as its own tab. Selecting one opens
  *its* detail page, and `MainActivity.detailsTrail` walks Back home one page at a time. On
  the direct path there is no engine, so `EmbyRepository.getRelated` returns Emby's
  `Items/{id}/Similar` with no reasons at all — both halves are allowed to be empty and the
  page still opens.
- **Nothing about related titles is allowed to fail.** It is asked for on *focus*
  (`HomeViewModel.focusItem` warms it while the card is highlighted), so it is the most
  frequently made request on the launcher and was by some way the loudest thing in the
  gateway's error log. `RelatedTo` now degrades at every step instead: a taste profile that
  cannot be built costs the reasons and not the carousel (`Why` falls back to catalogue
  facts, `FilterUnseen` keeps everything), a failed or empty `Similar` lookup falls through
  to `genreNeighbours` — the imported catalogue, in this title's genres, best rated first,
  which is also the only half that works while Emby is the thing that is down — and
  `relatedSubject` reads the item itself from `library_items` when Emby will not answer for
  it. The only error the engine still returns is the viewer having navigated on, and the
  handler answers that with silence rather than a logged 502. Two supporting rules: an
  empty carousel is cached for `relatedEmptyTTL` rather than the item lifetime, because a
  ten-minute answer must not outlive the minute of trouble that produced it; and
  client-side `getRelated` is single-flighted on the repository's own scope, so the
  cancelled focus prefetch neither aborts the request the detail page is about to want nor
  caches its own failure as an answer.
- `SeriesDetailsOverlay` and `MediaDetailsOverlay` only load (episodes, related, trailer) and
  delegate; `SeriesDetailContent`/`MediaDetailContent` are parameter-driven so they can be
  screenshotted (`DetailPageScreenshotTest`, which drives the tab strip by clicking it and
  also renders each pane on its own at `detailPaneHeight`) without a server.

**"Estimated finish: 18 August"** is `data/SeriesPace.kt`, a quiet line under the series
hero's progress bar. It is derived entirely from the episode list the detail page already
holds — Emby's per-episode `UserData.Played` and `LastPlayedDate` — which is the whole
design: there is no new storage, nothing to invalidate, and **no second implementation on
the direct path**, unlike the subtitle and Continue Watching rules. It is per viewer and
per series by construction, since that user data is Emby's and is keyed that way, and it
recalculates for free because finishing an episode, marking one watched, a history sync
from another client and a newly imported episode all change that list and nothing else.
Things to preserve:

- **Most of the function is about refusing to answer.** A wrong date is worse than none, so
  every guard returns null: fewer than three completions (two only when they are on
  separate days and within a week of each other), nothing watched in a month, one or zero
  episodes left, a horizon past a year. The load-bearing one is that the window must span
  **at least two distinct local days** — three episodes in one evening is a sitting, not a
  rate, and reading a daily pace off it is exactly how the opening of a binge promises a
  finish this week.
- **The window ends at the present and stops at the last break** (`sinceLastBreak`), rather
  than averaging a viewer's whole history with the show. Somebody who took a year over
  season one and is now watching nightly is watching nightly; including the silence
  predicts a finish years out.
- **Estimating and wording are separate functions.** `estimateSeriesPace` answers in
  numbers and `seriesPaceLabel` turns them into a sentence, so a "finish this weekend" row
  or a completion reminder can use the first without inheriting the second. Near dates are
  named and far ones rounded to weeks or months — a pace measured over a fortnight cannot
  honestly pick a day four months out.
- **"Catch up" is not a synonym for "finish".** `BaseItem.isOngoingSeries` prefers Sonarr's
  lifecycle where the gateway attached one and falls back to Emby's `Status`, which is the
  only source the direct path has; both absent means "finish", the weaker claim. `Status`
  is in `fieldsDetail` on both paths for this, and the gateway's item cache key moved to
  `item:v5:` so entries written before it cannot hide the field.
- **Quiet is the property a unit test cannot check**, so `SeriesPaceScreenshotTest` renders
  the line on a real hero → `build/screenshots/series-pace/`. It covers both spacing cases
  (with a progress bar above it and without), both verbs, and — the one worth keeping — the
  empty case, which must leave the hero identical with nothing holding the line's space.
  Its history is built relative to the clock rather than pinned, because a fixture with a
  fixed date would fall out of the recency window and capture the empty case by accident.
- **The date is formatted here, not by the platform.** `formatPaceDate` names the month
  from its own table so a set configured in US English cannot start printing "August 18"
  into New Zealand copy, and the civil-calendar arithmetic is hand-rolled because
  `java.time` needs API 26 and this app ships to 23 — the same reason `data/LocalDays.kt`
  writes out `floorDiv`. That file is where the local-day arithmetic now lives; it was
  private to `HomeMovieHero` while the daily hero rotation was its only caller.

**An episode has its own page.** `ui/EpisodeDetailsOverlay.kt`, reached whenever
`item.isEpisode` — which is what Continue Watching hands over. It is the same
`DetailPageScaffold` as the other two with two substitutions, both of them scaffold
parameters rather than a second layout:

- The logo belongs to the *series*, so the hero takes an `eyebrow` ("SEASON 3 · EPISODE 4")
  and a `subtitle` (the episode's own title) under it, plus a `title` override for the
  no-logo fallback — without that override the fallback heading printed the episode's name
  a second time.
- `strip` replaces the tab strip in the band under the hero, keeping the same
  `DetailStripHeight`, the same fold and the same focus contract (it is handed the requester
  above it, the one below it, and the callback that pins the page). An episode gets the
  **season scroller**: every season the library holds, the current one flagged WATCHING,
  earlier ones dimmed and ticked. The rules are pure and pinned in `EpisodeDetailTest` —
  seasons *before* the current one count as watched however patchy they are, seasons after
  never do however much has been sampled, and specials (season 0) are exempt from the
  "behind you" rule entirely because a tick on an unwatched special is a claim the page must
  not make. `seriesProgressLabel` counts numbered seasons only for the same reason.
- The pane under it is the selected season's episodes, opened on the episode the page is
  about and flagged THIS EPISODE. It reuses `EpisodeCard` from the series page rather than
  copying it, or the two screens drift on what a watched episode looks like.
- Screenshots are `EpisodeDetailScreenshotTest` → `build/screenshots/episode-detail/`.

**A schedule card opens the show, and says why.** The "Shows airing in the next 5 days"
row is informational — its cards are episodes that have not aired, `MembyPlayable: false`,
so pressing one used to do nothing at all. It now opens the *series* page, with the air
time restated on it (`ui/detail/AiringNotice.kt` → the accent band in `DetailPageScaffold`,
where the recommendation reason would otherwise sit). Four things hold it together:

- **The link is server-side.** `MembySeriesItemId` is resolved in `api/sonarr.go` by
  matching the Sonarr title (and year, which wins when both a remake and its original are
  in the library) against `store.SeriesRefs`. A show Sonarr follows but Emby has never
  imported carries none, and its card stays inert rather than opening an empty page.
- **The notice belongs to the route, not to the show.** `MainActivity.detailsAiringNotice`
  is set only by that row's `onItemSelected` and cleared everywhere else a page opens —
  including "More like this", which is why walking Back does not restore it. The same
  series reached from Favourites or search must never claim a schedule.
- **Its wording is the gateway's**, copied off the card (`membyAirLabel` and friends). The
  TV never derives an air time from a timestamp, so the page cannot contradict the card
  that was just pressed.
- **The page opens on a stub** (`scheduleSeriesStub`) and fills in from
  `HomeViewModel.focusItem`, the same swap `FocusedDetailsOverlay` already does — waiting on
  an item request before anything appears is what would make the row feel broken. The
  episode's own overview and artwork are deliberately dropped: they belong to the episode.

**One lifecycle word, one colour, three rows.** A schedule card and a My Shows card both
wear a tag saying whether the show is still being made or the film has actually come out —
CONTINUING, ENDED, IN CINEMAS — and `LifecycleBadge` in `HomeComponents.kt` is the single
place that colours them, so the same word never means two things on one launcher. Green is
still going, red is over, blue is not out yet, amber is in cinemas. Two things worth
keeping: the *wording* is the gateway's (`MembyLifecycleText`, from `api/lifecycle.go`) and
only the *slug* is a lookup key, so an *arr status a build predates still reads correctly
instead of falling back to a slug; and a card with no lifecycle wears no tag rather than an
invented one — an older gateway, a cached row, or a show *arr has no status for. The
availability badge above it answers a different question (has the household's copy
downloaded), which is why they occupy opposite corners. `myShowBadge` puts CANCELLED ahead
of everything else on a followed show: nothing else on that card matters as much.

**The TV calendar is the schedule row's other shape.** The launcher's row answers "what is
on this week"; `GET /v1/calendar` (`server/internal/api/calendar.go` → `ui/calendar/`)
answers "what is on this month, and when does it come back", which is a question no shelf
has a form for — so it is a rail destination with a weekly TV guide: seven days in a rail
and the selected day's artwork-led programme list beside it. It reuses
`toSonarrScheduleItem`, so a calendar card and a
schedule card are the same card, with the same availability badges, lifecycle tag and Emby
series link; pressing one makes the same substitution the row does (`scheduleSeriesStub` +
`airingNoticeFor`), because an episode that has not aired has no page of its own. Things to
preserve:

- **The television does no calendar arithmetic.** The gateway sends `firstWeekday`,
  `dayCount` and its own `today`; `calendarWeeks` lays out the month from those alone and
  `calendarAgendaWeeks` only pages those cells seven at a time. A
  set working out for itself which years are leap years, in its own zone rather than the
  household's, would be a second calendar free to disagree with the days the episodes were
  grouped into — which on the wrong side of midnight it would. The one thing the set does
  read its own clock for is *when to ask again*: `CalendarViewModel` drops every cached
  month once the device's local day changes, because everything else about a month is fixed
  and only `today` goes stale. Being wrong about that by an hour costs one request, where
  being wrong about the layout would draw a calendar that disagrees with itself.
- **A month is claimed by what was asked for, not by what arrives.** Cancelling a coroutine
  already past its last suspension point does not stop it, and a held D-pad on a month arrow
  is exactly how two requests come to be in flight — so a response is dropped unless it is
  still the month `requestedMonth` names. The cache is bounded for the same reason: "held
  for the life of the page" and "grows while somebody holds the D-pad" are otherwise the
  same sentence, and a month is a list of episodes with artwork behind it.
- **Focus is selection**, the stance the detail page's tab strip takes. A remote has no
  hover, and a calendar needing a press per day to say what is on it is one nobody reads. A
  press moves *into* the day panel; Back steps out of the panel before leaving the page.
- **Month and week travel are explicit controls.** Left and Right inside the guide already
  mean moving between the day rail and its programmes, so those keys cannot also change the
  date range. An arrow at the end of either range is not drawn rather than drawn dead.
  `calendarMonthRange` (12) is what stops a
  held D-pad walking Sonarr into the 2050s one request at a time; `parseCalendarMonth` refuses
  an out-of-range month rather than clamping, or the header would disagree with the grid.
- **The day rail summarises; the programme pane explains.** A day names its count and first
  show only. The pane has the space for Sonarr fanart (or a graphical monogram fallback), an
  Emby title logo when the series was matched, episode details, availability and a prominent
  season-premiere/finale label. Finale wording comes from Sonarr's `finaleType`; an absent
  value makes no claim. `CalendarScreenshotTest` renders a crowded day and the artwork-free
  fallback because only a screenshot can check that hierarchy at television distance.
- **The rail entry is a server feature** (`tv_calendar`, capability `tv_calendar_v1`), because
  a household running no Sonarr would otherwise carry a destination that only ever opens an
  apology. A set standing on the page when it is switched off is moved to Home, or it is left
  somewhere nothing can navigate back to.
- **A failed month is an empty month, not an error.** The page is informational, and somebody
  who pressed Right past a Sonarr hiccup must be able to press Left back out of it.
- **There is no second implementation on the direct path.** Unlike subtitles or Continue
  Watching, the answer is Sonarr's, which a television holds no credential for and Emby knows
  nothing about — with no gateway there is genuinely no calendar, and the rail says so by
  omitting the entry.

**Previews.** `ui/PreviewSupport.kt` holds the one preview shape: `@TvPreview` (1080p TV,
landscape, launcher black) plus `PreviewSurface { }` for the real theme. Use those rather
than a bare `@Preview`, which defaults to a phone and misrepresents every layout here.
A preview does not run `ServiceLocator`, so only composables that take their state as
parameters are previewable — the same property that makes them unit-testable. Prefer
previewing the still inner composable over an animated wrapper (`AlertBanner`, not
`ServiceAlertBanner`): a frozen frame of a slide-in shows nothing useful.

**Screenshots.** `OnboardingScreenshotTest` covers everything a new television shows before
the launcher — first run, the install-permission step in both its states, and sign-in empty,
filled, rejected, connecting and adding-a-viewer — into `build/screenshots/onboarding/`. It
is the sequence nobody sees twice and the one that decides whether that TV can ever update
itself, so being able to look at it without reinstalling on hardware matters more here than
anywhere else. It is also why `SignInContent` and `InstallPermissionContent` are stateless:
`SetupScreen` keeps the authentication, the content takes parameters.

`app/src/test/.../ServiceAlertBannerScreenshotTest.kt` renders composables
to PNGs under `app/build/screenshots/<feature-name>/` via Roborazzi + Robolectric, at TV 1080p qualifiers
— the way to look at a layout without a TV to hand. This is the *only* Android dependency
allowed in `app/src/test`; keep it confined to `*ScreenshotTest.kt` files so logic tests
stay pure JUnit. Recording is always on (`roborazzi.test.record` in `testOptions`): these
are artifacts to look at, not checked-in goldens, and a screenshot test that silently
captures nothing is worse than none. Give each feature its own kebab-case folder and keep
all variants of that feature together. AGP's own `com.android.compose.screenshot` plugin was
tried first and discovers zero previews on AGP 8.13.2 — don't re-litigate it without
checking that upstream.