docs(player): allocate UR-074/DR-162 for the streaming bitrate cap

The feature shipped tagged against DR-160, which a parallel session had
claimed for picture-in-picture in the meantime. Renumbered to DR-162
across the Rust and frontend TRACES comments (the PiP tags in
VideoPlayer.svelte, pictureInPicture.ts and nativeVideo.ts keep DR-160)
and regenerated bindings.ts.

Adds the requirement rows the tags point at: UR-074 for the user need, and
DR-162 covering why the cap has to reach the PlaybackInfo negotiation and
not only the transcode URL, why the ceiling is process-wide, and why the
Settings default persists while the in-player override does not. Notes
that this gives UR-070 its resume-at-the-same-point mechanism while the
server-offered rendition list that requirement also asks for stays
proposed. UT-156/157 record what the tests pin.

docs/specs/streaming-bitrate-cap.md carries the layer assignment — the
step definitions, the video/audio split, the resolution pairing and the
reload decision are all Rust; the frontend holds a serde token and the
labels it was handed.

TRACES: UR-074 | DR-162 | UT-156, UT-157

docs/requirements.md

@@ -84,6 +84,7 @@ For a narrative overview of the system design, see
 | UR-071 | Media the viewer is watching can be **kept**, by a whole-file download that runs in the background independently of playback and at its own quality, so it is unaffected by bitrate changes. Where the streamed bytes already are that file (direct play), they are kept rather than fetched twice. A completed download is then played from disk rather than streamed again | Medium | Proposed |
 | UR-073 | Watched state is something the viewer can **set**, not only something playback records. Any episode, season, series or movie can be marked watched — or unwatched again — from where it is shown, without sitting through it or erasing its history wholesale. Marking a season or series covers the episodes inside it, and works with the server unreachable | Medium | Done |
 | UR-072 | Each page opens where a page should open. Moving to a new screen starts at the top of it, and going Back returns the viewer to the place they left — their position in a long library grid or home screen, not the top of it. A page never inherits the scroll position of the page before it | Medium | Done |
+| UR-074 | Video streaming can be held to a **bandwidth budget the viewer sets**, rather than spent at whatever rate the server would otherwise send. A ceiling chosen once — from the source's own bitrate down to a rung that still plays on a poor connection — governs every video the app opens, live TV included, and survives a restart, so a metered connection is not quietly drained by the next thing played. A single video can be moved to a different ceiling from the player, resuming where it was, without disturbing that default | Medium | Done |
 
 ---
 
@@ -322,6 +323,7 @@ Internal architecture, components, and application logic.
 | DR-155 | A watch position set on another device reaches this one. The resume check reads the local `user_data` row and nothing else, but `mirror_user_data` — the only path by which server `UserData` lands in that table — mirrored `is_favorite` alone, and returned early whenever that field was absent, which is exactly the shape of an ordinary watched episode. So `playback_position_ticks` was write-only from this device's perspective: watch 40 minutes in a browser, open JellyTau, and it resumed from whatever *this* device last saw or offered no resume at all — the same user-visible symptom as DR-150's Android bug, from an unrelated cause, which is why resume read as broadly flaky. The mirror now carries the position alongside the favourite flag under the same `pending_sync = 0` conflict rule, so a local position still waiting to be pushed is never pulled *backwards* by a server that has not yet heard where we got to; `COALESCE(excluded.x, user_data.x)` means a field the server omitted keeps its stored value rather than being nulled, and a row with neither field is still skipped rather than fabricated as zeroes. Mirroring alone was not sufficient: `get_item` — the call the player route makes — returned the cached copy on a hit and never consulted the server, so for an already-cached item the mirror never ran. It now refreshes in the background on a cache hit (`race_with_refresh`, the reusable form of what `get_items` already did inline), which is why browsing a season picked up other devices' state while opening the episode directly did not. The refreshed value lands for the next read, the cache-first race still answering immediately | Backend | UR-025, UR-002 | Done |
 | DR-156 | A page no longer inherits the previous page's scroll position. The shell keeps its scrollers alive across navigation by design — the root layout, the home page and the library layout each own a `flex-1 overflow-y-auto` box that outlives the route inside it, which is what lets `BottomUi` be a flex sibling rather than a measured overlay — but the element therefore never remounts and its `scrollTop` survives the route change. SvelteKit's own scroll restoration could not help: it saves and restores `window` scroll, and in this app the window never scrolls at all, so there was no scroll handling of any kind. The symptom was that opening an item from half-way down a library grid dropped the viewer half-way down the detail page, and returning to the grid landed at the top of it — exactly backwards. `ScrollMemory` (pure, one instance per container, keyed on path + query so a genre-filtered grid keeps its own place) records the offset a route is left at in `beforeNavigate` and decides in `afterNavigate`: `link`/`goto`/`form` reset to the top, `popstate` restores that route's saved offset, and the initial `enter` is left alone. Deciding does not consume the offset, so a route returned to more than once restores each time. Applied via the `scrollContainer` action on all three scrollers | UI | UR-072 | Done |
 | DR-160 | Picture-in-picture works on the path that actually plays video. PiP shrinks the whole *Activity*, so `canEnterPip` demanded a native ExoPlayer `SurfaceView` be attached and rendering — `isPlayingVideo() && getSurfaceView() != null && isVideoSurfaceAttached()`. But the native path sits behind `experimentalNativeVideo`, which defaulted to **off**, so in the shipping configuration video played in the WebView's `<video>` element and all three conditions were false. `enterPip` bailed with "Not entering PiP: no local video playing" every single time: the button was offered (gated only on OS capability) and could not work, however it was pressed. The manager now accepts either surface. The frontend reports the element through `AndroidPictureInPicture.setHtml5VideoState(active, width, height, playing)` — intrinsic size because the PiP window's aspect ratio came from the letterboxed surface's measured bounds, which do not exist here, and play state because `ExoPlayer.isPlaying` is false on this path and the PiP play/pause action would be frozen on "Play" mid-playback. Two behaviours invert when the WebView *is* the video: it must stay visible in PiP rather than be hidden (`hideWebView` is now gated on the native path — hiding it would leave an empty black window), and the play/pause `RemoteAction` has to reach the element, so the receiver dispatches `jellytau-pip-play`/`jellytau-pip-pause` DOM events instead of driving ExoPlayer. `jellytau-pip-entered`/`-exited` let the player strip its own chrome, since controls, title and gradients would otherwise be rendered into a window a couple of inches wide. The `<video>` is deregistered on teardown so PiP is never offered over a video that has gone | UI | UR-041 | Done (pending device verification) |
+| DR-162 | Video streams are opened against a **bandwidth ceiling the user chose**, instead of a fixed allowance nobody could change. Every video URL carried `MaxStreamingBitrate=20000000`/`VideoBitrate=18000000`, `PlaybackInfo` negotiated at 20 Mbps, and the device profile advertised `999999999` — so on a metered or slow connection the only lever was not watching. `StreamingQuality` is a ladder of ceilings (Original, 20/10/8/4/2/1 Mbps, 720 kbps) in which a step is not a label but a bundle of transcode parameters: the total ceiling, the audio share of it, and the resolution that budget can carry. It lives in Rust because those numbers are Jellyfin encoding vocabulary — the frontend names a variant and reads labels back over `player_get_streaming_qualities`, the same arrangement as the EQ preset curves. The video bitrate is the total *minus* the audio share, so the two together honour the cap rather than overshooting it by the size of the audio track, and `MaxHeight` falls with the ladder so a small budget is not spent on pixels it cannot afford. The cap has to reach the **negotiation**, not only the transcode URL: `max_static_bitrate` in the device profile is what makes the server refuse to direct-play a source fatter than the ceiling, and without it a 30 Mbps remux is handed over untouched and every URL parameter downstream is moot — which is why it is applied at all four places that decide bandwidth (the HLS builder, `PlaybackInfo`, `open_live_stream`, and the background-audio handoff, which takes the lower of the cap and its own 384 kbps). The ceiling is process-wide rather than a field on `OnlineRepository`, mirroring `INCLUDE_CATALOG_BROWSE`: it is a preference about *this device's connection*, it must survive a repository rebuilt on re-login, and every builder plus the negotiation have to agree on it or the cap leaks. Settings owns the durable default and is the only writer to `app_settings` — persisted unlike the rest of `VideoSettings`, because a limit set for a metered connection that silently reverts to uncapped on the next launch spends the user's data with no changed setting to show for it — and it is restored at startup from the async runtime, defaulting to uncapped if the read fails so a database problem degrades to the old behaviour rather than to an arbitrary limit. The in-player menu is the per-video override: a cap is a property of the stream the server is producing, so it cannot be applied to one already in flight — `player_set_stream_quality` re-opens the stream at the new quality and resumes at the current position, reloading a native backend itself and handing HTML5 a URL for the same `reloadSource` primitive the audio-track switch uses, so no strategy branch lives in the UI. It deliberately does not persist. This gives UR-070 its resume-at-the-same-point mechanism; the server-offered per-item rendition list that requirement also asks for remains proposed | Playback | UR-074, UR-070 | Done |
 | DR-161 | Native video is the default, so picture-in-picture has a real surface. DR-160 makes PiP work on the HTML5 path, but that path can only ever shrink the *UI* into the PiP window; showing the video itself needs the SurfaceView behind the WebView, which is what `experimentalNativeVideo` gates. The flag now defaults to on when the user has never chosen, with an explicit stored choice still winning in both directions so anyone who turned it off keeps it off. This is a deliberate acceptance of risk: the flag existed because the native path was an unfinished spike, and `VideoPlayer.scrubRegression.test.ts` documents its history — a native init that flipped to HTML5 mid-lifecycle and left seeks going down one path while ExoPlayer played on another. Those tests pin the **flag-off** interim override (native response overridden to HTML5, backend stopped once), which the default no longer selects, so they now mock the flag off rather than inherit it: they still guard that path, but they no longer describe what ships. The native scrub/seek path is consequently not covered by the suite and needs device verification | UI | UR-041, UR-003 | Needs device verification |
 | DR-159 | The background-audio handoff stops leaking its relative timeline. The handoff plays the episode as a *relative* stream — the audio-only URL is built with `StartTimeTicks` = the position the screen was locked at, so ExoPlayer's zero is the handoff point — and `background_audio_base` holds the offset that turns one back into a real position. The base was a **display-only** correction, applied in exactly two places (the lockscreen scrubber and the internal truncation maths) while every other consumer worked in the relative timeline treating the number as absolute. Each crossing threw away exactly `base` seconds, which is why the jump-back distance varied with where the screen was locked and read as random. Three crossings were live: progress reporting to Jellyfin sent the relative position every 30s, so the server was told `real − base` — and since DR-155 now mirrors the server's position back and refreshes on a cache hit, that regressed value returned as the resume point (lock at 40 min, listen to 90, reopen at 50); lockscreen seeks went out absolute and came back relative, against a chunked length-less transcode that cannot honour a seek at all, so a clamped seek landed at stream zero; and media3's own `seekToDefaultPosition`/`seekBack`/`seekForward` bypassed the `ForwardingPlayer` wrapper entirely, reaching the real ExoPlayer — `Util.handlePlayButtonAction` seeking an ended player to the relative zero being the same mechanism as DR-129's truncation bug through a different door. The fix converts **once, at the boundary**: `JellyTauPlayer`'s position tick adds the base (and shifts the duration with it, since the stream's own length is only what remains) before either `nativeOnPositionUpdate` or the lockscreen sees it, so position updates, progress reports, the frontend and the truncation check all speak the episode's timeline and none needs to know a handoff happened. The base is consequently *removed* from `claim_stream_resume`, `truncated_stream_resume_position` and `player_exit_background_audio`, where adding it now double-counts, and the lockscreen's `positionOffsetMs` addition goes with it (the field remains, read-only, as the tick's input). Inbound seeks go the other way: `seek_absolute` is the new boundary for every outside seek, re-opening the stream at the requested position via `resume_stream_at` when a handoff is active — which is what `onSeekTo` had claimed for months in a comment describing code that did not exist — and an ordinary seek otherwise. `seekToDefaultPosition` is swallowed rather than forwarded, since Rust already owns what "play after the stream ended" means and the `play()` that follows reaches it. Exit reads the position *before* clearing either base, or a tick landing in between hands back a relative one | Player | UR-040, UR-005, UR-025 | Done (pending device verification) |
 | DR-158 | A watched toggle, on the episode row, the season header, the series and movie hero, and the Episode Focus View. Both halves of the backend already existed and neither had a caller: `mark_played` (`POST /PlayedItems`) was reachable only from the sync drain replaying rows the *reporter* had queued, and `clear_watch_history` (`DELETE /PlayedItems`) only from the destructive "erase this series' history" button — so the sole way to mark something watched was to play it. Jellyfin applies both recursively over a season or series, so the container case needs no client-side fan-out *online*. Offline it does: `storage_set_watched` writes the item **and its descendants** (drawn from `items` by `parent_id`/`album_id`/`season_id`/`series_id`, so an uncached id selects nothing and the statement no-ops instead of raising a foreign-key error), because otherwise marking a season watched with no server would tick the season and leave every episode inside it unwatched. It is deliberately separate from `storage_mark_played`, which stays the single-item "this finished playing" path that increments `play_count`. Un-marking clears the resume position as well as the flag, matching the server. `QueuedOp::MarkUnplayed` gives the queue the missing direction — pushing as `clear_watch_history` — so the toggle works offline both ways rather than only one; without it un-marking would have been the half that needed a connection. The button is an everyday toggle, so unlike `ClearHistoryButton` it does not confirm, and it holds an optimistic state because the caller's `watched` prop only catches up after a reload (a season means a round trip, during which the button would otherwise appear to ignore the tap) | UI | UR-073 | Done |
@@ -413,6 +415,7 @@ Internal architecture, components, and application logic.
 | UR-071 | IR-032 | DR-123, DR-124, DR-125, DR-126, DR-127, DR-128, DR-133, DR-134, DR-135, DR-136, DR-137, DR-138 |
 | UR-072 | - | DR-156 |
 | UR-073 | - | DR-158 |
+| UR-074 | - | DR-162 |
 
 ---
 
@@ -565,6 +568,8 @@ Internal architecture, components, and application logic.
 | UT-152 | Caching a server result mirrors its watch position locally — including for an item carrying a position but no favourite flag — without inventing a row for an item the server reported no user data for, and without pulling a still-unsynced local position backwards | DR-155 | Done |
 | UT-155 | A seek during a background-audio handoff re-opens the stream at the requested absolute position (`StartTimeTicks`) and rebases the handoff to it, while a seek outside a handoff stays an ordinary seek and invents no base | DR-159 | Done |
 | UT-154 | `mark_unplayed` parses to `QueuedOp::MarkUnplayed` and is rejected without an item id, and a queued un-mark drains to the server as `clear_watch_history` | DR-158 | Done |
+| UT-156 | A capped step reaches the transcode URL as all four of its parts (total ceiling, the video/audio split summing to the cap, and a `MaxHeight`), the uncapped default keeps the historical 20/18 Mbps allowance and constrains no resolution, and the background-audio handoff takes the lower of the cap and its own 384 kbps | DR-162 | Done |
+| UT-157 | The quality ladder is internally consistent — video + audio equals the cap at every step, audio never consumes the budget, only `Original` is uncapped — descends in bitrate, resolution and audio share together, and round-trips through the serde token it is persisted as | DR-162 | Done |
 | UT-153 | Scroll handling per navigation kind: a forward move always lands at the top even when the previous page was scrolled and even when the target was visited before, Back restores that route's own saved offset (and the top when it has none), offsets are kept per route rather than shared, a repeated Back still restores, and the initial load leaves the container alone | DR-156 | Done |
 | UT-142 | The audio codecs offered for video direct play: a Dolby device's real `MediaCodecList` output drops `ac3`/`eac3`, AMR and raw PCM are dropped too, a fully-supported list is passed through untouched, a list with nothing decodable still claims `aac`, and stray spacing or casing does not decide whether the user gets sound | DR-148 | Done |
 | UT-143 | Subtitle URLs resolve to plain strings before they reach the markup (never a Promise), unresolvable tracks are dropped, a stale selection collapses to "Off", and a server-default track is never auto-selected | UR-020, DR-023 | Done |