Merge remote-tracking branch 'origin/master' into feature/sticky-search-and-music-seek

# Conflicts:
#	README.md
#	docs/architecture.md

README.md

@@ -331,6 +331,15 @@ Then put it behind your existing reverse proxy like everything else
 - [x] Sticky search bar on the library/artist/album pages, and letting
       anyone seek within the current music track (same no-host-check
       model pause/resume already had) — see docs/architecture.md
+- [x] Skip intro / jump to next episode at end credits, using Emby's own
+      native marker detection (`EnableMarkerDetection` + its "Detect
+      Episode Intros" task) rather than building fingerprinting
+      ourselves — see docs/architecture.md
+- [x] Report each party member's own playback to Emby's real Sessions
+      API (`/Sessions/Playing`, `/Progress`, `/Stopped`), so the admin
+      dashboard sees watch-party streams the same way it sees a native
+      client's — one session per member, under their own account — see
+      docs/architecture.md
 - [ ] Try a full party end-to-end with two real accounts (still the main gap)
 - [ ] Try casting to a real Chromecast (only the SDK's own bootstrap is
       confirmed here — no real device/session)

client/src/api/embyApi.ts

@@ -3,7 +3,7 @@
 // module just wraps fetch calls to our own /api/* routes. See
 // docs/architecture.md for why this changed from the first version (CORS,
 // plus not wanting the browser to hold an Emby token at all).
-import type { ItemDto, LibraryDto, PlaybackOptionsDto, SeasonDto } from '../types';
+import type { ItemDto, LibraryDto, PlaybackMarkersDto, PlaybackOptionsDto, SeasonDto } from '../types';
 
 async function apiFetch<T>(path: string, options: RequestInit = {}): Promise<T> {
   const res = await fetch(path, {
@@ -116,6 +116,10 @@ export function getPlaybackOptions(itemId: string): Promise<PlaybackOptionsDto>
   return apiFetch(`/api/catalog/item/${itemId}/playback-options`);
 }
 
+export function getPlaybackMarkers(itemId: string): Promise<PlaybackMarkersDto> {
+  return apiFetch(`/api/catalog/item/${itemId}/markers`);
+}
+
 /** The party's own shared Emby stream (server/src/services/
  *  PartyStreamService.ts) - one negotiated PlaybackInfo session reused
  *  by every member, instead of each viewer's own <video>/<audio>

client/src/types.ts

@@ -50,6 +50,16 @@ export interface PlaybackOptionsDto {
   subtitleTracks: PlaybackTrackOption[];
 }
 
+/** Emby's own native intro/credits detection - see server/src/types.ts's
+ *  own copy of this shape for where the field names come from. Every
+ *  field is independently nullable ("not detected", never an error) -
+ *  see views/player/Player.ts's updateSkipButton, the only consumer. */
+export interface PlaybackMarkersDto {
+  introStartTicks: number | null;
+  introEndTicks: number | null;
+  creditsStartTicks: number | null;
+}
+
 export type MediaType = 'video' | 'music';
 
 export interface PublicMember {

client/src/views/player/Player.css

@@ -196,6 +196,26 @@
   transition: padding .25s ease, background-color .25s ease, border-color .25s ease;
 }
 
+/* Floating above #bottomBar (higher z-index, positioned clear of its
+   tallest/expanded height) rather than living inside it - see
+   Player.html's own comment on why: it must stay reachable through the
+   bar's own auto-hide/.minimal collapse, not disappear along with it. */
+.skipMarkerBtn {
+  position: absolute;
+  right: 10px;
+  bottom: 84px;
+  z-index: 7;
+  background: rgba(20, 18, 22, .85);
+  color: white;
+  border: 1px solid rgba(255, 255, 255, .25);
+  padding: 10px 18px;
+  border-radius: 6px;
+  font-size: 13px;
+  font-weight: 600;
+}
+
+.skipMarkerBtn:hover { background: rgba(20, 18, 22, .95); border-color: rgba(255, 255, 255, .4); }
+
 /* Collapsed down to just the seek bar after a stretch of no activity
    (see Player.ts's scheduleControlsHide) - asked for directly: the
    full bar, always visible, sits right where a native <track> subtitle

client/src/views/player/Player.html

@@ -63,6 +63,17 @@
        notification rather than a fourth thing bolted onto a fixed layout. -->
   <div id="requestBanner" class="requestBanner hide"></div>
 
+  <!-- Emby's own native intro detection (see Player.ts's updateSkipButton/
+       CatalogService.getPlaybackMarkers) - shown independently of #bottomBar
+       below, and NOT subject to its own auto-hide/.minimal collapse, since
+       this needs to stay reachable the moment the intro starts even if
+       nobody's touched the player yet. Host-only, like every other seek -
+       see updateSkipButton's own comment for why a follower can't get this
+       button at all. Explicit label, not just an icon - see
+       docs/architecture.md's player-rework section for why this app
+       standardized on that for every request-shaped control. -->
+  <button id="skipIntroBtn" class="skipMarkerBtn hide">Passer l'intro</button>
+
   <!-- One bar, bottom-anchored, replacing what used to be three separate
        floating pieces (a centered banner/notice column, a request
        toolbar cornered bottom-right, an "Épisode suivant" link up in the

client/src/views/player/Player.ts

@@ -1,14 +1,14 @@
 import '../../styles/presence.css';
 import './Player.css';
 import html from './Player.html';
-import { auth, burnInStreamUrl, getPlaybackOptions, partyStreamUrl, subtitleUrl } from '../../api/embyApi';
+import { auth, burnInStreamUrl, getPlaybackMarkers, getPlaybackOptions, partyStreamUrl, subtitleUrl } from '../../api/embyApi';
 import { getParty, leaveParty, connectParty, issueCastToken, revokeCastToken } from '../../api/party';
 import type { PartyConnection } from '../../api/party';
 import { navigate } from '../../router';
 import type { CleanupFn, RouteParams } from '../../router';
 import { colorForName, escapeHtml, formatDuration, initialsFor } from '../../tiles';
 import { LOADING_HINT } from '../../loading';
-import type { BurnInChangedMsg, ItemChangedMsg, PartyPublicState, PauseRequestedMsg, PlaybackOptionsDto, ResumeRequestedMsg, SocketMember, StreamOptionsChangedMsg, TextSubtitleChangedMsg } from '../../types';
+import type { BurnInChangedMsg, ItemChangedMsg, PartyPublicState, PauseRequestedMsg, PlaybackMarkersDto, PlaybackOptionsDto, ResumeRequestedMsg, SocketMember, StreamOptionsChangedMsg, TextSubtitleChangedMsg } from '../../types';
 import { joinMusicParty, leaveMusicParty } from '../../musicBar/MusicBar';
 import { initCast, localDriver, onCastAvailabilityChanged, onCastSessionEnded, startCast, stopCast } from '../../cast';
 import type { PlaybackDriver } from '../../cast';
@@ -203,6 +203,7 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
   const playPauseBtn = root.querySelector('#playPauseBtn') as HTMLButtonElement;
   const muteBtn = root.querySelector('#muteBtn') as HTMLButtonElement;
   const timeLabel = root.querySelector('#timeLabel')!;
+  const skipIntroBtn = root.querySelector('#skipIntroBtn') as HTMLButtonElement;
 
   qualitySelect.innerHTML = QUALITY_PRESETS.map((q) => `<option value="${q.value}">${q.label}</option>`).join('');
 
@@ -262,6 +263,15 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
   // - see its own comment) can re-render the subtitle picker's host-only
   // gating for burn-in options without a redundant playback-options fetch.
   let lastPlaybackOptions: PlaybackOptionsDto | null = null;
+  // Emby's own native intro/credits detection for currentItemId, if any -
+  // see loadMarkers/updateSkipButton below and CatalogService
+  // .getPlaybackMarkers. Null fields (or this whole thing being null,
+  // while still loading) just mean no skip button, never an error.
+  let currentMarkers: PlaybackMarkersDto | null = null;
+  // One-shot per item - see updateSkipButton's own comment for why this
+  // must NOT re-fire (force the bar open) on every tick for as long as
+  // credits are running.
+  let creditsControlsShown = false;
   // "The player" sendLocalState/applyRemoteState actually read and write -
   // the local <video> by default, swapped for a Chromecast's RemotePlayer
   // while casting (see toggleCast/cast.ts). Casting is available to any
@@ -427,6 +437,42 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
     timeLabel.textContent = duration > 0 ? `${formatDuration(current)} / ${formatDuration(duration)}` : '';
   }
 
+  /**
+   * Shows/hides #skipIntroBtn from activeDriver's current position against
+   * currentMarkers - called continuously (progressTicker, below), same as
+   * updateProgressBar. Host-only: a follower's own seek never broadcasts
+   * (see sendLocalState's own gate), so a local jump here would just get
+   * overwritten by the next correction from the real host - same
+   * reasoning as progressBar being read-only for a follower.
+   *
+   * Credits get no button of their own: #nextBtn already does exactly
+   * "go to the next queued item" and is already shown whenever
+   * hasNextQueued is true (see onItemChanged) - detection's only real
+   * contribution there is making sure it's actually reachable the moment
+   * credits start, by un-minimizing the bar once, rather than requiring
+   * the host to have touched the player recently. The `creditsControlsShown`
+   * guard is what keeps this a one-shot nudge instead of fighting anyone
+   * who deliberately re-minimizes the bar during a long credits scroll.
+   */
+  function updateSkipButton() {
+    if (!isHost || !currentMarkers) {
+      skipIntroBtn.classList.add('hide');
+      return;
+    }
+    const current = activeDriver.currentTime;
+    const { introStartTicks, introEndTicks, creditsStartTicks } = currentMarkers;
+
+    const inIntro = introStartTicks != null && introEndTicks != null
+      && current >= introStartTicks / TICKS_PER_SECOND && current < introEndTicks / TICKS_PER_SECOND;
+    skipIntroBtn.classList.toggle('hide', !inIntro);
+
+    const inCredits = creditsStartTicks != null && current >= creditsStartTicks / TICKS_PER_SECOND;
+    if (inCredits && hasNextQueued && !creditsControlsShown) {
+      creditsControlsShown = true;
+      showControls();
+    }
+  }
+
   /** Shared by every discrete play/pause/seek event this player reacts
    *  to - the local <video>'s own native events (becomeHost) and a cast
    *  session's RemotePlayerController events (startCasting's own
@@ -505,6 +551,12 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
     updateMuteBtn();
   });
 
+  skipIntroBtn.addEventListener('click', () => {
+    if (currentMarkers?.introEndTicks == null) return;
+    activeDriver.currentTime = currentMarkers.introEndTicks / TICKS_PER_SECOND;
+    onDriverStateChanged();
+  });
+
   // Ticks the seek bar/time label between discrete events - currentTime
   // moves continuously while playing, with no event of its own for
   // "still playing, time passed" the way play/pause/seeked have. Runs
@@ -515,6 +567,7 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
   progressTicker = window.setInterval(() => {
     if (!currentItemId) return;
     updateProgressBar();
+    updateSkipButton();
   }, 500);
   updatePlayPauseBtn();
   updateMuteBtn();
@@ -656,6 +709,24 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
     }
   }
 
+  /** Emby's own native intro/credits markers for `itemId`, if the library
+   *  it's from has detection enabled and the task has already reached it
+   *  - see CatalogService.getPlaybackMarkers. Reset first, synchronously,
+   *  not just on a fetch failure: without this, the OLD item's markers
+   *  (and skip button) would keep showing for however long this fetch
+   *  takes on the new one. */
+  async function loadMarkers(itemId: string) {
+    currentMarkers = null;
+    skipIntroBtn.classList.add('hide');
+    creditsControlsShown = false;
+    try {
+      currentMarkers = await getPlaybackMarkers(itemId);
+    } catch (err) {
+      console.error('[watchparty player] playback markers failed', err);
+      // Non-fatal, same as loadTrackOptions above - playback works fine with no skip button.
+    }
+  }
+
   /**
    * (Re)builds the subtitle <select> from the last-fetched playback
    * options, called both on a genuine item load and whenever burn-in/
@@ -940,6 +1011,7 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
     burnInAudioIndex = null;
     textSubtitleIndex = null;
     streamAudioIndex = null;
+    loadMarkers(msg.itemId); // not awaited - never needed before playback can start, see loadVideo below
     await loadTrackOptions(msg.itemId);
     loadVideo(msg.itemId, 0, true);
   }
@@ -1102,6 +1174,7 @@ function renderVideoPlayer(root: HTMLElement, partyId: string, party: PartyPubli
     // image-subtitle option as disabled, as if they were a follower.
     if (party.youAreHost) becomeHost(false);
 
+    loadMarkers(party.itemId); // not awaited - see onItemChanged's own comment
     await loadTrackOptions(party.itemId);
     loadVideo(party.itemId, 0, false);
 

docs/architecture.md

@@ -3176,6 +3176,173 @@ so that was checked by reading `.mainContent`'s own layout directly
 `position: sticky` resolves against the page scroll as intended, not
 some inner element).
 
+## Skipping the intro/end credits, using Emby's own native detection
+
+Asked for directly: propose skipping a TV episode's opening/end credits,
+Netflix-style. Checked directly against the real server before building
+anything, rather than assuming a data source existed - no plugin
+provides this (the installed "Cinema Intros" plugin is a different
+feature entirely - pre-show trailers, not per-episode skip points), and
+the embedded `Chapters` Emby already returns turned out to be
+auto-generated placeholders every 5 minutes ("Chapitre 1", "Chapitre
+2", ...), not real markers.
+
+What the server DOES have, confirmed from its own `/openapi.json`
+rather than assumed: a native, per-library `EnableMarkerDetection`
+option (`Library/VirtualFolders`'s `LibraryOptions`) backed by a
+built-in "Detect Episode Intros" scheduled task - audio-fingerprint
+detection, the same idea as Jellyfin's separate Intro Skipper plugin,
+just already part of Emby itself. Once enabled and run, it adds real
+entries to the exact same `Chapters` array, distinguished from the
+auto-generated ones by `MarkerType`: `IntroStart`/`IntroEnd`/
+`CreditsStart` (confirmed from the schema, not guessed - there is no
+`CreditsEnd`, since credits are assumed to run to the end of the file).
+
+Given that, this feature is almost entirely "read what Emby already
+computed and expose it" - no fingerprinting, no new persistence, no
+background jobs of this app's own. `CatalogService.getPlaybackMarkers`
+fetches `Fields=Chapters` for an item and picks out just those three
+marker types (nulls when detection hasn't reached this item, or isn't
+enabled for its library - never an error), behind a new
+`GET /api/catalog/item/:id/markers` route, mirroring
+`getPlaybackOptions`'s own shape exactly.
+
+**The player side** adds one new floating button, `#skipIntroBtn` -
+explicit label ("Passer l'intro"), not an icon, matching this app's own
+established convention for every request-shaped control. It's
+positioned as a sibling of `#bottomBar`, not inside it, specifically so
+it stays reachable through the bar's own auto-hide/`.minimal` collapse -
+someone who hasn't touched the player still needs to see it the moment
+the intro starts. `updateSkipButton` (ticked every 500ms alongside
+`updateProgressBar`) compares `activeDriver.currentTime` against the
+fetched markers and shows/hides it; clicking it seeks straight to
+`introEndTicks` through the exact same `activeDriver`/`onDriverStateChanged`
+path any other seek already uses, so it's automatically host-only (a
+follower's seek never broadcasts - see `sendLocalState`'s own gate) and
+automatically cast-aware (works identically whether `activeDriver` is
+the local `<video>` or a Chromecast's `RemotePlayer`) with no new
+special-casing for either.
+
+End credits deliberately got no button of their own: `#nextBtn` already
+does exactly "go to the next queued item" and was already shown
+whenever `hasNextQueued` is true, for the whole episode - not something
+this feature needed to duplicate. The only real gap it closes is
+*visibility*: if nobody's touched the player in a while, `#bottomBar`
+(and `#nextBtn` inside it) is collapsed to `.minimal` right when
+credits start. `updateSkipButton` calls the existing `showControls()`
+once (a `creditsControlsShown` flag keeps it one-shot, not a fight
+against someone deliberately re-minimizing the bar during a long
+credits scroll) the moment playback crosses `creditsStartTicks`, so the
+already-existing button is actually reachable without requiring a mouse
+nudge first.
+
+Verified: full `typecheck`/`test`/`build` on both projects (125/125
+server tests, including new coverage for `getPlaybackMarkers` - the
+real `MarkerType` values mixed with auto-generated `Chapter` ones, and
+both "no Chapters field" and "no markers among the Chapters that are
+there" resolving to nulls rather than throwing). The button's on-screen
+position was checked directly (`getBoundingClientRect` against the real
+compiled CSS, not eyeballed) - it sits clear of `#bottomBar` with a
+10px gap at both a 960×540 and a phone-width viewport, since both use
+fixed pixel offsets off the same `.playerWrap`. **Not verified**: the
+detection task had only just been enabled on the real server (confirmed
+via its own `EnableMarkerDetection`/`ScheduledTasks` state) and hadn't
+finished analyzing any episode yet at the time this shipped, so the
+actual end-to-end "does a detected marker make the button appear at
+the right second" behavior is unconfirmed against real generated data -
+worth a real check once the task has had time to run.
+
+## Making Emby's own admin dashboard see watch-party streams
+
+Asked for directly: Emby's admin "now playing" dashboard should see
+this app's streams the same way it sees a real web/mobile/TV client's -
+this is exactly the follow-up "Sync watch-party progress back to Emby"
+(above) already anticipated and deliberately deferred, word for word:
+"wiring clean start/stop into every transition... is real complexity
+for a secondary payoff, left as a documented follow-up rather than
+built speculatively." That section also already explains why: this app
+switched entirely to direct `UserData` writes for resume-position/
+watched-history, abandoning Emby's session-shaped `PlayingItems`
+endpoints, precisely because they need a real session lifecycle to mean
+anything - and given that section's own history (two separate rounds of
+a wrong-but-schema-plausible request shape for that *other*,
+now-abandoned endpoint family), this one was built carefully, checking
+the real API before writing anything rather than assuming.
+
+**Confirmed against the real server's own `/openapi.json`** (not
+assumed) that the actual session-lifecycle family is `POST
+/Sessions/Playing` (start), `/Sessions/Playing/Progress`, and
+`/Sessions/Playing/Stopped` - distinct from the `PlayingItems` family
+`PlaystateService` already walked away from. None of the three schemas
+declare a `required` list at all, which - given this exact neighboring
+history - was read as "don't trust that," not "everything's optional
+in practice": `ItemId`/`MediaSourceId`/`PlaySessionId`/`PositionTicks`
+are sent on every call anyway, matching what a real client obviously
+would, rather than risking a repeat of the earlier "technically matches
+the schema, still 400s" experience.
+
+**One real Emby session per PARTY MEMBER, not one per party** - a
+faithful copy of how a real client behaves (every device/account gets
+its own), and the actual point of "let admin see who's watching what"
+would be lost by collapsing every member onto one shared entry. New
+`server/src/services/EmbySessionService.ts` (`start`/`progress`/`stop`)
+mirrors `PlaystateService`'s own shape closely - same best-effort
+philosophy (every failure caught and logged, never thrown), same
+`Logger.playstate` category (broadened to describe both) - but is kept
+as its own class rather than folded into `PlaystateService`, since that
+class's entire opening comment is specifically about why it *doesn't*
+use a session-shaped endpoint; mixing the two would muddy exactly the
+distinction that comment goes out of its way to draw.
+
+**Getting a `MediaSourceId`/`PlaySessionId` per member** needed a new
+`CatalogService.negotiatePlaybackSession(session, itemId)` - a fresh
+`PlaybackInfo` negotiation under that specific member's own account.
+This can't reuse `PartyStreamService`'s existing shared negotiation:
+that one is negotiated once, under whichever member happened to
+trigger it first, and Emby scopes `PlaybackInfo` per user - never
+guaranteed valid for reporting under everyone else's own account too.
+Returns `null` on any failure rather than throwing (an expired token,
+Emby unreachable, no source) - unlike `getMediaSource`'s own hard
+failure (which feeds a real ffmpeg source and has to fail loudly), this
+one only ever feeds an admin-dashboard nicety.
+
+**Driven entirely from index.ts's existing periodic sweep**, not new
+hooks scattered across every queue-advance/track-skip call site the way
+`PlaystateService.markPlayed` needed. That sweep already visits every
+connected member on every ~20s tick - exactly positioned to notice
+"this member's current item no longer matches `PartyMember
+.embySession.itemId`" and react: stop the old session if there was
+one, negotiate fresh ids, start the new one. The same item as last tick
+just sends a Progress report reusing the already-cached ids - no
+renegotiation needed for the common case. `PartyMember` gained the
+nullable `embySession` field this reads/writes (same null-until-known
+shape as `embyToken`/`deviceId`). Explicit `stop` calls also happen at
+the two places a member's session should end promptly rather than
+waiting on the next sweep tick to just stop reporting: `PartyService
+.leave()` (alongside the existing `CastTokenService.revokeForMember`)
+and `removeIdleParties` (a defensive backstop for a member whose own
+disconnect-driven `leave()` never fired for some reason - a real gap
+would otherwise leave a stale dashboard entry indefinitely, not just
+until the next tick).
+
+Verified: full `typecheck`/`test`/`build` (140/140 server tests - new
+coverage for `negotiatePlaybackSession`'s null-on-any-failure
+contract, every `EmbySessionService` method's exact request shape and
+that a non-ok response/thrown error is swallowed not propagated, and
+that `leave()` calls `stop` with a member's real cached session info
+but only when they actually had one open). **Not verified**: an actual
+live write against the real server - deliberately not attempted from
+here, since doing so would mean using a real account's Emby token for
+a genuine state-changing call, beyond the read-only diagnostic use
+this session's shared API key was ever meant for. So while the request
+shape is checked against the real schema and the per-member logic is
+unit-tested in full, whether Emby's dashboard actually displays these
+sessions the way a native client's would - correct device/client
+labeling in particular, since this app never sends the `X-Emby-
+Authorization` Device/Client/Version header a real client would, only
+`X-Emby-Token` - is genuinely unconfirmed. Worth watching the real
+dashboard the first time a party runs after this ships.
+
 ## Known limitations
 
 - Playback always goes through `hls.js` against whatever Emby's

server/package.json

@@ -9,7 +9,7 @@
     "start": "node dist/index.js",
     "dev": "tsx watch src/index.ts",
     "typecheck": "tsc -p tsconfig.test.json",
-    "test": "tsx --test test/castTokenService.test.ts test/catalogService.test.ts test/embyClient.test.ts test/musicQueueService.test.ts test/partyService.test.ts test/partyStreamService.test.ts test/playstateService.test.ts test/socketGateway.test.ts test/transcodeService.test.ts"
+    "test": "tsx --test test/castTokenService.test.ts test/catalogService.test.ts test/embyClient.test.ts test/embySessionService.test.ts test/musicQueueService.test.ts test/partyService.test.ts test/partyStreamService.test.ts test/playstateService.test.ts test/socketGateway.test.ts test/transcodeService.test.ts"
   },
   "engines": {
     "node": ">=18"

server/src/Logger.ts

@@ -66,17 +66,20 @@ export class Logger {
     console.log(`[watchparty:transcode] ${new Date().toISOString()} ${message}`);
   }
 
-  /** The party watch-state sync (index.ts's periodic sweep, and
-   *  PartyService.advanceQueue/MusicQueueService.playNext's own item-
-   *  transition calls - see PlaystateService) - logs every outgoing
-   *  request (method + path, and the POST body for the UserData write)
-   *  and its outcome, not just failures: this is a best-effort
-   *  background sync with nothing else watching it, so `docker logs |
-   *  grep watchparty:playstate` needs to be enough on its own to see
-   *  exactly what was sent and whether Emby accepted it, without cross-
-   *  referencing `emby` above. Safe to log in full here (unlike `stream`
-   *  above) - the real embyToken travels as a header, never logged, and
-   *  PlaystateService's own tests confirm it never leaks into these lines. */
+  /** Every per-member background write this app makes to Emby under
+   *  someone's own account - the party watch-state sync (index.ts's
+   *  periodic sweep, and PartyService.advanceQueue/MusicQueueService
+   *  .playNext's own item-transition calls - see PlaystateService), and
+   *  the parallel Sessions-API lifecycle reported alongside it (see
+   *  EmbySessionService). Logs every outgoing request (method + path,
+   *  and the POST body for the UserData write) and its outcome, not
+   *  just failures: this is a best-effort background sync with nothing
+   *  else watching it, so `docker logs | grep watchparty:playstate`
+   *  needs to be enough on its own to see exactly what was sent and
+   *  whether Emby accepted it, without cross-referencing `emby` above.
+   *  Safe to log in full here (unlike `stream` above) - the real
+   *  embyToken travels as a header, never logged, and both services'
+   *  own tests confirm it never leaks into these lines. */
   static playstate(message: string): void {
     console.log(`[watchparty:playstate] ${new Date().toISOString()} ${message}`);
   }

server/src/index.ts

@@ -14,6 +14,7 @@ import { MusicQueueService } from './services/MusicQueueService';
 import { TranscodeService } from './services/TranscodeService';
 import { PartyStreamService } from './services/PartyStreamService';
 import { PlaystateService } from './services/PlaystateService';
+import { EmbySessionService } from './services/EmbySessionService';
 import { CastTokenService } from './services/CastTokenService';
 import { SocketGateway } from './realtime/SocketGateway';
 import type { ClientToServerEvents, EmbySession, MediaType, QueueItem, ServerToClientEvents } from './types';
@@ -212,6 +213,13 @@ app.get('/api/catalog/item/:itemId/playback-options', requireSession, asyncRoute
   res.json(await CatalogService.getPlaybackOptions(req.embySession!, param(req, 'itemId')));
 }));
 
+// Emby's own native intro/credits detection, when the library it's from has
+// the feature enabled - powers the player's "Passer l'intro"/"Épisode
+// suivant" buttons. See CatalogService.getPlaybackMarkers.
+app.get('/api/catalog/item/:itemId/markers', requireSession, asyncRoute(async (req, res) => {
+  res.json(await CatalogService.getPlaybackMarkers(req.embySession!, param(req, 'itemId')));
+}));
+
 app.get('/api/catalog/libraries/:libraryId/items', requireSession, asyncRoute(async (req, res) => {
   res.json({ items: await CatalogService.getLibraryItems(req.embySession!, param(req, 'libraryId')) });
 }));
@@ -606,6 +614,17 @@ setInterval(() => PartyStreamService.reapIdleSessions(30 * 60 * 1000), 5 * 60 *
 // Marking an item Played (once the party moves past it) is handled
 // separately, at the source of that transition - see
 // PartyService.advanceQueue and MusicQueueService.playNext.
+//
+// Also where EmbySessionService's own start/progress/stop lifecycle is
+// driven from, rather than scattered across every queue-advance/track-
+// skip call site the way markPlayed needed to be - this loop already
+// visits every connected member on every tick, so it's already in
+// exactly the right place to notice "this member's current item just
+// changed" (member.embySession.itemId no longer matches) and react:
+// stop the old session if there was one, negotiate a fresh
+// MediaSourceId/PlaySessionId under their own account, and start the
+// new one. Same item as last tick just reports Progress with the
+// already-cached ids - no renegotiation needed for that, the common case.
 setInterval(() => {
   for (const party of PartyService.listActive()) {
     const state = PartyService.getCurrentPlaybackState(party);
@@ -613,6 +632,35 @@ setInterval(() => {
     for (const member of party.members.values()) {
       if (!member.connection || !member.embyToken) continue;
       PlaystateService.updatePosition(member.embyToken, member.userId, state.itemId, state.positionTicks);
+
+      if (member.embySession && member.embySession.itemId === state.itemId) {
+        const s = member.embySession;
+        EmbySessionService.progress(member.embyToken, s.itemId, s.mediaSourceId, s.playSessionId, state.positionTicks, state.isPaused);
+        continue;
+      }
+
+      // The item just changed for them (or this is the first tick since
+      // they started watching/listening) - stop whatever they had open
+      // before, if anything, then negotiate and start a fresh one.
+      const previous = member.embySession;
+      const embyToken = member.embyToken;
+      member.embySession = null;
+      if (previous) {
+        EmbySessionService.stop(embyToken, previous.itemId, previous.mediaSourceId, previous.playSessionId, member.positionTicks);
+      }
+      // CatalogService's own methods all take a full EmbySession, for
+      // consistency with every live user-facing route that already has
+      // one from requireSession - this sweep only ever has a member's
+      // bare stored token, same situation PlaystateService/
+      // EmbySessionService are already in. serverId/createdUtc are safe
+      // to fake: negotiatePlaybackSession (like every per-member Emby
+      // write in this app) never reads either, only embyToken/userId.
+      const fakeSession: EmbySession = { embyToken, userId: member.userId, userName: member.userName, serverId: '', createdUtc: 0 };
+      CatalogService.negotiatePlaybackSession(fakeSession, state.itemId).then((negotiated) => {
+        if (!negotiated) return;
+        member.embySession = { itemId: state.itemId, mediaSourceId: negotiated.mediaSourceId, playSessionId: negotiated.playSessionId };
+        EmbySessionService.start(embyToken, state.itemId, negotiated.mediaSourceId, negotiated.playSessionId, state.positionTicks, state.isPaused);
+      });
     }
   }
 }, 20 * 1000);

server/src/services/CatalogService.ts

@@ -4,7 +4,7 @@ import type { Request, Response } from 'express';
 import { EMBY_SERVER_URL } from '../config';
 import { EmbyClient } from '../emby/EmbyClient';
 import { Logger } from '../Logger';
-import type { EmbyItem, EmbySession, ItemDto, LibraryDto, MediaType, PlaybackOptionsDto, SeasonDto } from '../types';
+import type { EmbyItem, EmbySession, ItemDto, LibraryDto, MediaType, PlaybackMarkersDto, PlaybackOptionsDto, SeasonDto } from '../types';
 
 // 'MusicVideo' is Emby's own item type for a musicvideos library's
 // contents (distinct from the generic 'Video', which is home videos).
@@ -286,6 +286,30 @@ class CatalogServiceClass {
     };
   }
 
+  /**
+   * Emby's own native intro/credits detection - see PlaybackMarkersDto's
+   * own comment for what MarkerType actually looks like and where that
+   * was confirmed. Read from the same Chapters field getRawItem/toItemDto
+   * never request (they have no use for chapters at all) - a dedicated
+   * fetch here rather than folding it into getItem, since a chapter list
+   * is only ever needed by the player deciding whether to show a skip
+   * button, nowhere a plain ItemDto is used.
+   */
+  async getPlaybackMarkers(session: EmbySession, itemId: string): Promise<PlaybackMarkersDto> {
+    const data = await this.fetchJson<{ Chapters?: Array<{ StartPositionTicks: number; MarkerType?: string }> }>(
+      `/Users/${session.userId}/Items/${itemId}?Fields=Chapters`,
+      session,
+      'Impossible de récupérer les marqueurs de lecture.'
+    );
+    const chapters = data.Chapters || [];
+    const startOf = (markerType: string) => chapters.find((c) => c.MarkerType === markerType)?.StartPositionTicks ?? null;
+    return {
+      introStartTicks: startOf('IntroStart'),
+      introEndTicks: startOf('IntroEnd'),
+      creditsStartTicks: startOf('CreditsStart')
+    };
+  }
+
   /**
    * The negotiated MediaSource's id/container/streams - used by
    * TranscodeService to build its own ffmpeg source URL and translate
@@ -307,6 +331,33 @@ class CatalogServiceClass {
     return { id: source.Id, container: source.Container || 'mkv', streams: source.MediaStreams || [] };
   }
 
+  /**
+   * A fresh PlaybackInfo negotiation under `session`'s own account,
+   * purely to get the MediaSourceId/PlaySessionId EmbySessionService
+   * needs to open a real Emby Sessions-API entry for this member - see
+   * its own class comment for why every party member needs their own,
+   * rather than reusing the one PartyStreamService already negotiated
+   * for the party's actual shared relay (that one was negotiated once,
+   * under whichever member happened to trigger it first - never
+   * guaranteed valid for every OTHER member's own account, since Emby
+   * scopes PlaybackInfo per user). Null on any failure (an expired
+   * token, Emby unreachable, no source at all) rather than throwing -
+   * this is reported to an admin dashboard as a nice-to-have, never
+   * something that should be allowed to disrupt real playback the way
+   * getMediaSource's own hard failure is allowed to (that one feeds an
+   * actual ffmpeg source).
+   */
+  async negotiatePlaybackSession(session: EmbySession, itemId: string): Promise<{ mediaSourceId: string; playSessionId: string } | null> {
+    try {
+      const info = await this.fetchJson<PlaybackInfoResponse>(`/Items/${itemId}/PlaybackInfo?UserId=${session.userId}`, session, 'Impossible de négocier une session de lecture.');
+      const source = (info.MediaSources || [])[0];
+      if (!source?.Id || !info.PlaySessionId) return null;
+      return { mediaSourceId: source.Id, playSessionId: info.PlaySessionId };
+    } catch {
+      return null;
+    }
+  }
+
   // --- Direct proxying (images/video/audio) - these need the raw
   // Express req/res, unlike everything above which just returns JSON. ---
 

server/src/services/EmbySessionService.ts

@@ -0,0 +1,104 @@
+'use strict';
+
+import { EmbyClient } from '../emby/EmbyClient';
+import { Logger } from '../Logger';
+
+/**
+ * Reports a party member's own playback to Emby's real Sessions API
+ * (`POST /Sessions/Playing`, `/Sessions/Playing/Progress`,
+ * `/Sessions/Playing/Stopped`) - the piece of session lifecycle
+ * docs/architecture.md's "Sync watch-party progress back to Emby"
+ * section deliberately deferred at the time ("wiring clean start/stop
+ * into every transition... is real complexity for a secondary payoff").
+ * Asked for directly since: without this, this app's own streams never
+ * showed up in Emby's admin "now playing" dashboard the way a real web/
+ * mobile/TV client's would - only the resume-position/watched-history
+ * UserData (PlaystateService) was ever visible anywhere, and only by
+ * opening the item itself, not from the dashboard's live session list.
+ *
+ * One real Emby session per PARTY MEMBER, not one per party - a
+ * faithful copy of how a real client behaves (every device/account gets
+ * its own), and the actual point of the request ("let admin see who's
+ * watching what") would be lost by collapsing every member onto one
+ * shared entry. Every call needs the member's own `embyToken` (the same
+ * source every other per-member Emby write in this app already uses -
+ * see `PartyMember.embyToken`/`PlaystateService`) - Emby's Sessions API
+ * is inherently per-account, there's no equivalent of "the party's" own
+ * session to report against instead.
+ *
+ * `MediaSourceId`/`PlaySessionId` (see `CatalogService
+ * .negotiatePlaybackSession`) are required in practice, not just
+ * present in the schema - confirmed by reading the real server's own
+ * `/openapi.json` rather than assumed, after this exact neighboring
+ * area (`PlaystateService`'s own history) already got bitten twice by
+ * an Emby endpoint accepting a request shape that looked complete but
+ * wasn't. `index.ts`'s periodic sweep is what actually drives the
+ * start/progress/stop transitions - see its own comment for why that
+ * one place could cover this instead of scattering hooks across every
+ * queue-advance/track-skip call site the way `PlaystateService
+ * .markPlayed` needed to.
+ *
+ * Best-effort throughout, exactly like `PlaystateService`: any failure
+ * is caught and logged here, never thrown - none of this may ever
+ * disrupt real playback over an admin-dashboard nicety.
+ */
+class EmbySessionServiceClass {
+  /** Called once per member when they start watching/listening to
+   *  `itemId` - a fresh join, or the party moving to a new item while
+   *  they're already a member (see index.ts's sweep, which detects that
+   *  by comparing against `PartyMember.embySession.itemId`). */
+  async start(embyToken: string, itemId: string, mediaSourceId: string, playSessionId: string, positionTicks: number, isPaused: boolean): Promise<void> {
+    await this.report('/Sessions/Playing', embyToken, {
+      ItemId: itemId,
+      MediaSourceId: mediaSourceId,
+      PlaySessionId: playSessionId,
+      PositionTicks: Math.round(positionTicks),
+      IsPaused: isPaused,
+      PlayMethod: 'Transcode',
+      CanSeek: true
+    });
+  }
+
+  /** Called periodically (~20s, alongside `PlaystateService
+   *  .updatePosition` - see index.ts's sweep) for every member with a
+   *  live session already open for their current item. */
+  async progress(embyToken: string, itemId: string, mediaSourceId: string, playSessionId: string, positionTicks: number, isPaused: boolean): Promise<void> {
+    await this.report('/Sessions/Playing/Progress', embyToken, {
+      ItemId: itemId,
+      MediaSourceId: mediaSourceId,
+      PlaySessionId: playSessionId,
+      PositionTicks: Math.round(positionTicks),
+      IsPaused: isPaused,
+      PlayMethod: 'Transcode'
+    });
+  }
+
+  /** Called once per member when they stop watching/listening to
+   *  `itemId` - leaving the party (`PartyService.leave`), the item
+   *  changing (index.ts's sweep), or the party being destroyed for
+   *  inactivity (`PartyService.removeIdleParties`). */
+  async stop(embyToken: string, itemId: string, mediaSourceId: string, playSessionId: string, positionTicks: number): Promise<void> {
+    await this.report('/Sessions/Playing/Stopped', embyToken, {
+      ItemId: itemId,
+      MediaSourceId: mediaSourceId,
+      PlaySessionId: playSessionId,
+      PositionTicks: Math.round(positionTicks)
+    });
+  }
+
+  /** Every call logs its own outgoing request + outcome - see
+   *  Logger.playstate's own comment for why this needs to be enough on
+   *  its own, greppable, to answer "is this actually reaching Emby, and
+   *  with what" for this service too, not just PlaystateService. */
+  private async report(path: string, embyToken: string, body: Record<string, unknown>): Promise<void> {
+    Logger.playstate(`-> POST ${path} itemId=${body.ItemId}`);
+    try {
+      const res = await EmbyClient.fetch(path, embyToken, { method: 'POST', body });
+      Logger.playstate(`<- ${res.status} ${res.ok ? 'ok' : 'FAILED'} ${path} itemId=${body.ItemId}`);
+    } catch (err) {
+      Logger.playstate(`<- threw ${path} itemId=${body.ItemId}: ${(err as Error).message}`);
+    }
+  }
+}
+
+export const EmbySessionService = new EmbySessionServiceClass();

server/src/services/PartyService.ts

@@ -7,6 +7,7 @@ import { TranscodeService } from './TranscodeService';
 import { PartyStreamService } from './PartyStreamService';
 import { PlaystateService } from './PlaystateService';
 import { CastTokenService } from './CastTokenService';
+import { EmbySessionService } from './EmbySessionService';
 import type { LeaveResult, MediaType, Party, PartyMember, PartyPublicState, QueueItem } from '../types';
 
 /**
@@ -157,6 +158,15 @@ class PartyServiceClass {
     party.lastActivityUtc = Date.now();
     MusicQueueService.removeVote(party, userId); // no-op for a video party (party.music is unset)
     CastTokenService.revokeForMember(party.id, userId); // no-op if they never cast - see its own comment for why this runs unconditionally, not just on an explicit "stop casting"
+    // No-op if they never had a live Emby Sessions-API entry (never
+    // connected, or the periodic sweep hadn't reached them yet) - see
+    // EmbySessionService's own comment. Fire-and-forget, same as every
+    // other per-member Emby report in this app - it already swallows its
+    // own failures, and leaving the party must never wait on Emby.
+    if (leavingMember?.embyToken && leavingMember.embySession) {
+      const s = leavingMember.embySession;
+      EmbySessionService.stop(leavingMember.embyToken, s.itemId, s.mediaSourceId, s.playSessionId, leavingMember.positionTicks);
+    }
 
     let newHostUserId: string | null = party.hostUserId;
     if (wasHost) {
@@ -256,6 +266,17 @@ class PartyServiceClass {
         MusicQueueService.destroy(party); // same leak this class's own destroy path guards against
         TranscodeService.endSession(party.id); // same leak - see the "leave" destroy path above
         PartyStreamService.endSession(party.id);
+        // Same reasoning, for any member whose own "leave" (a clean
+        // disconnect) never fired for whatever reason - a real gap would
+        // otherwise leave a stale entry sitting in Emby's own dashboard
+        // indefinitely, not just until the next sweep tick the way a
+        // still-connected member's stale Progress report would.
+        for (const member of party.members.values()) {
+          if (member.embyToken && member.embySession) {
+            const s = member.embySession;
+            EmbySessionService.stop(member.embyToken, s.itemId, s.mediaSourceId, s.playSessionId, member.positionTicks);
+          }
+        }
         const idleMinutes = Math.round((Date.now() - party.lastActivityUtc) / 60000);
         Logger.party(`destroyed partyId=${party.id} (idle ${idleMinutes}min, ${party.members.size} member(s) still connected)`);
       }
@@ -311,7 +332,8 @@ class PartyServiceClass {
       embyToken: null,
       isPaused: true,
       positionTicks: 0,
-      lastUpdatedUtc: Date.now()
+      lastUpdatedUtc: Date.now(),
+      embySession: null
     };
   }
 }

server/src/types.ts

@@ -224,6 +224,25 @@ export interface PlaybackOptionsDto {
   subtitleTracks: PlaybackTrackOption[];
 }
 
+/**
+ * Emby's own native intro/credits detection (a library's own
+ * EnableMarkerDetection option, run by its "Detect Episode Intros"
+ * scheduled task - confirmed directly against a real server's
+ * /openapi.json: MarkerType is one of Chapter/IntroStart/IntroEnd/
+ * CreditsStart, mixed into the same Chapters array as the auto-generated
+ * per-5-minutes ones). Every field is nullable, independently - the task
+ * may not have reached this item yet, the library may not have the
+ * feature enabled at all (it's per-library, not global), or a real
+ * cold-open episode may genuinely have no IntroStart/IntroEnd. None of
+ * that is an error - see CatalogService.getPlaybackMarkers - a caller
+ * just checks each field for null before offering the matching skip
+ * button. */
+export interface PlaybackMarkersDto {
+  introStartTicks: number | null;
+  introEndTicks: number | null;
+  creditsStartTicks: number | null;
+}
+
 // --- Party (video) -----------------------------------------------------------
 
 /** One entry in a video party's fixed, pre-built queue (a movie/standalone
@@ -260,6 +279,22 @@ export interface PartyMember {
   lastUpdatedUtc: number;
   lastPauseRequestUtc?: number;
   lastResumeRequestUtc?: number;
+  /** This member's own live Emby Sessions-API entry, if one's currently
+   *  open - see EmbySessionService. Null whenever they don't have one
+   *  (not connected/no token yet, or the periodic sweep hasn't started
+   *  one for their current item yet). `itemId` is what the sweep compares
+   *  against on each tick to notice an item change (stop the old
+   *  session, start a fresh one) - `mediaSourceId`/`playSessionId` are
+   *  cached here specifically so a Progress report can reuse them
+   *  without renegotiating PlaybackInfo on every single tick. */
+  embySession: EmbyPlaybackSession | null;
+}
+
+/** See PartyMember.embySession's own comment. */
+export interface EmbyPlaybackSession {
+  itemId: string;
+  mediaSourceId: string;
+  playSessionId: string;
 }
 
 /** The full internal party record - never sent to the client as-is, see

server/test/catalogService.test.ts

@@ -117,6 +117,42 @@ describe('CatalogService', () => {
     assert.equal(options.subtitleTracks.find((t) => t.index === 4)?.isTextBased, true, 'ass is text too');
   });
 
+  it('getPlaybackMarkers picks out Intro/Credits markers by MarkerType, ignoring the auto-generated Chapter ones', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({
+      Chapters: [
+        { StartPositionTicks: 0, Name: 'Chapitre 1', MarkerType: 'Chapter' },
+        { StartPositionTicks: 50000000, MarkerType: 'IntroStart' },
+        { StartPositionTicks: 900000000, MarkerType: 'IntroEnd' },
+        { StartPositionTicks: 3000000000, Name: 'Chapitre 2', MarkerType: 'Chapter' },
+        { StartPositionTicks: 20000000000, MarkerType: 'CreditsStart' }
+      ]
+    }));
+
+    const markers = await CatalogService.getPlaybackMarkers(session, 'item1');
+
+    assert.equal(markers.introStartTicks, 50000000);
+    assert.equal(markers.introEndTicks, 900000000);
+    assert.equal(markers.creditsStartTicks, 20000000000);
+  });
+
+  it('getPlaybackMarkers returns nulls, not an error, when the item has no detected markers at all', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({
+      Chapters: [{ StartPositionTicks: 0, Name: 'Chapitre 1', MarkerType: 'Chapter' }]
+    }));
+
+    const markers = await CatalogService.getPlaybackMarkers(session, 'item1');
+
+    assert.deepEqual(markers, { introStartTicks: null, introEndTicks: null, creditsStartTicks: null });
+  });
+
+  it('getPlaybackMarkers returns nulls when the item has no Chapters field at all', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({}));
+
+    const markers = await CatalogService.getPlaybackMarkers(session, 'item1');
+
+    assert.deepEqual(markers, { introStartTicks: null, introEndTicks: null, creditsStartTicks: null });
+  });
+
   it('proxySubtitle asks Emby for this track as WebVTT, using the negotiated MediaSourceId', async (t) => {
     t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({ MediaSources: [{ Id: 'src7' }] }));
     let capturedTarget = '';
@@ -169,6 +205,35 @@ describe('CatalogService', () => {
     );
   });
 
+  it('negotiatePlaybackSession returns the MediaSourceId/PlaySessionId a Sessions-API report needs', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({
+      MediaSources: [{ Id: 'src1' }],
+      PlaySessionId: 'play1'
+    }));
+
+    const result = await CatalogService.negotiatePlaybackSession(session, 'item1');
+
+    assert.deepEqual(result, { mediaSourceId: 'src1', playSessionId: 'play1' });
+  });
+
+  it('negotiatePlaybackSession returns null, not a throw, when Emby has no media source at all', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({ MediaSources: [], PlaySessionId: 'play1' }));
+
+    assert.equal(await CatalogService.negotiatePlaybackSession(session, 'item1'), null);
+  });
+
+  it('negotiatePlaybackSession returns null when Emby omits PlaySessionId, even with a real source', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => jsonResponse({ MediaSources: [{ Id: 'src1' }] }));
+
+    assert.equal(await CatalogService.negotiatePlaybackSession(session, 'item1'), null);
+  });
+
+  it('negotiatePlaybackSession returns null, not a throw, when the negotiation itself fails', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => new Response(null, { status: 500 }) as unknown as Response);
+
+    assert.equal(await CatalogService.negotiatePlaybackSession(session, 'item1'), null);
+  });
+
   it('getPlaylistItemsRaw asks Emby\'s own /Playlists endpoint, in order', async (t) => {
     let capturedPath = '';
     t.mock.method(EmbyClient, 'fetch', async (path: string) => {

server/test/embySessionService.test.ts

@@ -0,0 +1,91 @@
+// Exercises EmbySessionService directly against a mocked EmbyClient - no
+// real Emby server involved. Covers the request shape each of the three
+// Sessions-API calls sends and that a failure (a non-ok response, or a
+// thrown error) is swallowed rather than propagated - see the class's
+// own comment for why none of this may ever be allowed to disrupt real
+// playback over an admin-dashboard nicety.
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { EmbySessionService } from '../src/services/EmbySessionService';
+import { EmbyClient } from '../src/emby/EmbyClient';
+
+function okResponse(): Response {
+  return new Response(null, { status: 204 }) as unknown as Response;
+}
+
+describe('EmbySessionService', () => {
+  it('start() POSTs to /Sessions/Playing with the negotiated ids and the given position/pause state', async (t) => {
+    let capturedPath = '';
+    let capturedToken = '';
+    let capturedBody: unknown = null;
+    t.mock.method(EmbyClient, 'fetch', async (path: string, token: string, options: { body?: unknown }) => {
+      capturedPath = path;
+      capturedToken = token;
+      capturedBody = options.body;
+      return okResponse();
+    });
+
+    await EmbySessionService.start('tok1', 'item1', 'src1', 'play1', 12_345, false);
+
+    assert.equal(capturedPath, '/Sessions/Playing');
+    assert.equal(capturedToken, 'tok1');
+    assert.deepEqual(capturedBody, {
+      ItemId: 'item1',
+      MediaSourceId: 'src1',
+      PlaySessionId: 'play1',
+      PositionTicks: 12_345,
+      IsPaused: false,
+      PlayMethod: 'Transcode',
+      CanSeek: true
+    });
+  });
+
+  it('progress() POSTs to /Sessions/Playing/Progress', async (t) => {
+    let capturedPath = '';
+    t.mock.method(EmbyClient, 'fetch', async (path: string) => {
+      capturedPath = path;
+      return okResponse();
+    });
+
+    await EmbySessionService.progress('tok1', 'item1', 'src1', 'play1', 999, true);
+
+    assert.equal(capturedPath, '/Sessions/Playing/Progress');
+  });
+
+  it('stop() POSTs to /Sessions/Playing/Stopped', async (t) => {
+    let capturedPath = '';
+    let capturedBody: unknown = null;
+    t.mock.method(EmbyClient, 'fetch', async (path: string, _token: string, options: { body?: unknown }) => {
+      capturedPath = path;
+      capturedBody = options.body;
+      return okResponse();
+    });
+
+    await EmbySessionService.stop('tok1', 'item1', 'src1', 'play1', 42);
+
+    assert.equal(capturedPath, '/Sessions/Playing/Stopped');
+    assert.deepEqual(capturedBody, { ItemId: 'item1', MediaSourceId: 'src1', PlaySessionId: 'play1', PositionTicks: 42 });
+  });
+
+  it('rounds a fractional PositionTicks rather than sending a non-integer', async (t) => {
+    let capturedBody: { PositionTicks?: number } = {};
+    t.mock.method(EmbyClient, 'fetch', async (_path: string, _token: string, options: { body?: unknown }) => {
+      capturedBody = options.body as { PositionTicks?: number };
+      return okResponse();
+    });
+
+    await EmbySessionService.progress('tok1', 'item1', 'src1', 'play1', 12_345.6, false);
+
+    assert.equal(capturedBody.PositionTicks, 12_346);
+  });
+
+  it('a non-ok response is logged, not thrown', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => new Response(null, { status: 401 }) as unknown as Response);
+    await assert.doesNotReject(() => EmbySessionService.start('tok1', 'item1', 'src1', 'play1', 0, false));
+  });
+
+  it('a thrown network error is logged, not propagated', async (t) => {
+    t.mock.method(EmbyClient, 'fetch', async () => { throw new Error('network down'); });
+    await assert.doesNotReject(() => EmbySessionService.stop('tok1', 'item1', 'src1', 'play1', 0));
+  });
+});

server/test/musicQueueService.test.ts

@@ -49,7 +49,8 @@ function fakeMember(userId: string, userName: string, embyToken: string): PartyM
     embyToken,
     isPaused: false,
     positionTicks: 0,
-    lastUpdatedUtc: Date.now()
+    lastUpdatedUtc: Date.now(),
+    embySession: null
   };
 }
 

server/test/partyService.test.ts

@@ -4,6 +4,7 @@ import { PartyService } from '../src/services/PartyService';
 import { MusicQueueService } from '../src/services/MusicQueueService';
 import { PlaystateService } from '../src/services/PlaystateService';
 import { CastTokenService } from '../src/services/CastTokenService';
+import { EmbySessionService } from '../src/services/EmbySessionService';
 import type { AppSocket } from '../src/types';
 
 describe('PartyService', () => {
@@ -127,6 +128,33 @@ describe('PartyService', () => {
     assert.deepEqual(calls, [[party.id, 'u-bob']]);
   });
 
+  it('leave() stops whatever Emby Sessions-API entry the leaving member had open', (t) => {
+    const calls: unknown[][] = [];
+    t.mock.method(EmbySessionService, 'stop', async (...args: unknown[]) => { calls.push(args); });
+
+    const party = PartyService.create('u-alice', 'Alice', 'm1', 'Un Film', '/img/m1', null, 'video');
+    const bob = PartyService.join(party, 'u-bob', 'Bob');
+    bob.embyToken = 'tok-bob';
+    bob.positionTicks = 555;
+    bob.embySession = { itemId: 'm1', mediaSourceId: 'src1', playSessionId: 'play1' };
+
+    PartyService.leave(party, 'u-bob');
+
+    assert.deepEqual(calls, [['tok-bob', 'm1', 'src1', 'play1', 555]]);
+  });
+
+  it('leave() does not call EmbySessionService.stop for a member with no open session', (t) => {
+    let called = false;
+    t.mock.method(EmbySessionService, 'stop', async () => { called = true; });
+
+    const party = PartyService.create('u-alice', 'Alice', 'm1', 'Un Film', '/img/m1', null, 'video');
+    PartyService.join(party, 'u-bob', 'Bob'); // embyToken/embySession both still null - see newMember
+
+    PartyService.leave(party, 'u-bob');
+
+    assert.equal(called, false);
+  });
+
   it('join() is idempotent: re-joining an existing member returns it as-is instead of resetting it', () => {
     const party = PartyService.create('u-alice', 'Alice', 'm1', 'Un Film', '/img/m1', null, 'video');
     const bob = PartyService.join(party, 'u-bob', 'Bob');