From de1c13e72f8e1d805fe0aedaf81534dfb3e7ed25 Mon Sep 17 00:00:00 2001
From: Duncan Tourolle <duncan@tourolle.paris>
Date: Sun, 16 Aug 2026 10:23:00 +0200
Subject: [PATCH] fix(player,reporting): report real positions, and count an
 audio-only episode as watched
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Returning to the foreground before the background-audio stream had started
playing handed the frontend 0.0s, so the video reloaded at StartTimeTicks=0 —
the episode restarted from the beginning — and the stop report that followed
wrote that zero to Jellyfin as the resume point. Caught on device: locked at
18.4s, unlocked 3.5s later with ExoPlayer still IDLE.

The base that turns a handoff's relative timeline into the episode's is applied
once at the native tick boundary (DR-159), so before the first tick nothing has
applied it. The same blind spot covers webview-rendered media, where nothing is
loaded into the native backend at all and its position is a permanent 0 — which
is why 14 of 14 stop reports in a 35-minute trace were zeroes, one landing 40s
after the frontend had correctly reported 15:22 for the same episode.

- absolute_position(): the maximum of the backend's reading, the last position
  webview media reported, and the handoff base. Exact rather than heuristic —
  at most one term is ever meaningful, and the base is a floor the stream
  cannot physically be behind. duration() gains the same fallback.
- Withhold zero-position stop reports. A zero is never information, and
  Jellyfin stores the reported position as the resume point, so sending one
  only ever destroys a real one.
- Report progress from the controller's own position ticks, through the 30s
  throttler it already shared with the native audio path.
  /Sessions/Playing/Progress was previously requested zero times in 35 minutes.
- Report a finished audio-only episode stopped at its runtime before advancing,
  so Jellyfin's 90% rule marks it played. Nothing else can: the webview is
  suspended and its <video> was torn down at the handoff.
- Split the handoff by source — a downloaded file takes no base and a real
  seek, a stream keeps its StartTimeTicks base and no seek — and stop routing a
  downloaded handoff's absolute seek through the stream rebuild, which refuses
  a non-remote source outright.

Reports go through a PlaybackReportSink, which also collapses three copies of
spawn-a-task-and-hope into one and is what let each of these be written as a
failing test first.

TRACES: UR-005, UR-025, UR-040, UR-071 | DR-178, DR-179, DR-180 |
        UT-176, UT-177, UT-178, UT-179, UT-180, UT-181
---
 src-tauri/src/commands/player/mod.rs  | 131 ++++-
 src-tauri/src/player/mod.rs           | 814 ++++++++++++++++++++++----
 src-tauri/src/player/stream_end.rs    |  12 +
 src/lib/services/playbackReporting.ts |  25 +-
 4 files changed, 853 insertions(+), 129 deletions(-)

diff --git a/src-tauri/src/commands/player/mod.rs b/src-tauri/src/commands/player/mod.rs
index bc2ab566..15f41e2b 100644
--- a/src-tauri/src/commands/player/mod.rs
+++ b/src-tauri/src/commands/player/mod.rs
@@ -454,6 +454,49 @@ pub(super) fn background_audio_source(
     }
 }
 
+/// How a background-audio handoff must start playback, given where its audio
+/// actually begins.
+///
+/// TRACES: UR-040, UR-071 | DR-180 | UT-181
+pub(super) struct BackgroundAudioPlan {
+    /// The position the stream's own zero corresponds to, recorded as the
+    /// handoff base so later readings can be shifted back to the episode's
+    /// timeline.
+    pub base_seconds: f64,
+    /// Where to seek after loading, if the source does not already start there.
+    pub seek_to: Option<f64>,
+}
+
+/// Decide the base and the seek for a handoff at `position_seconds`.
+///
+/// The two sources start in different places. An audio-only **stream** is built
+/// with `StartTimeTicks`, so the server makes the handoff point that stream's
+/// zero: the base is the handoff position, and seeking would skip *past* the
+/// content by that much again. A downloaded **file** has no such parameter and
+/// begins at the episode's own zero, so it needs the opposite — no base, and a
+/// real seek. Treating a file like a stream is why backgrounding a downloaded
+/// episode restarted it from 0:00 while the lockscreen showed the right time.
+///
+/// TRACES: UR-040, UR-071 | DR-180 | UT-181
+pub(super) fn background_audio_plan(
+    is_local_file: bool,
+    position_seconds: f64,
+) -> BackgroundAudioPlan {
+    let position = position_seconds.max(0.0);
+
+    if is_local_file {
+        BackgroundAudioPlan {
+            base_seconds: 0.0,
+            seek_to: (position > 0.0).then_some(position),
+        }
+    } else {
+        BackgroundAudioPlan {
+            base_seconds: position,
+            seek_to: None,
+        }
+    }
+}
+
 /// Resolve the on-disk file backing a completed download, if there is one.
 ///
 /// A `downloads` row is not proof of a file: it can outlive the bytes (manual
@@ -710,6 +753,9 @@ pub async fn player_enter_background_audio(
             item.id
         );
     }
+    // A downloaded file starts at the episode's zero; a stream starts at the
+    // handoff point. Only one of them has a base, and only the other needs a seek.
+    let plan = background_audio_plan(local_path.is_some(), position_seconds);
     let source = background_audio_source(local_path, item.stream_url, &item.id);
 
     // Build an AUDIO media item pointing at the audio-only stream. We do not use
@@ -753,21 +799,28 @@ pub async fn player_enter_background_audio(
     // Same base offset drives the lockscreen scrubber: ExoPlayer reports position
     // relative to the stream's StartTimeTicks zero, but the metadata duration is
     // absolute, so shift the reported position back to absolute for the scrubber.
-    let _ = crate::player::set_lockscreen_position_offset(position_seconds.max(0.0));
+    let _ = crate::player::set_lockscreen_position_offset(plan.base_seconds);
 
     let controller = player.0.lock().await;
-    // Remember where the video was: the audio stream's zero == this position
-    // (the URL was built with StartTimeTicks=position_seconds), so on exit we add
-    // this base to the native player's relative position to get the absolute one.
-    // The controller owns it so a backend-driven advance to the next episode
-    // clears it along with the stream it described.
-    controller.enter_background_audio(position_seconds);
+    // Remember where the video was: for a stream the audio's zero == this
+    // position (the URL was built with StartTimeTicks=position_seconds), so on
+    // exit we add this base to the native player's relative position to get the
+    // absolute one. The controller owns it so a backend-driven advance to the
+    // next episode clears it along with the stream it described.
+    controller.enter_background_audio(plan.base_seconds);
     controller
         .play_item(media_item)
         .map_err(|e| e.to_string())?;
-    // NOTE: do NOT seek here. The audio-only URL already starts at the handoff
-    // position via StartTimeTicks; the stream's timeline begins at 0 == that
-    // point, so an extra seek(position_seconds) would jump PAST the content.
+    // Seek ONLY a local file. The audio-only URL already starts at the handoff
+    // position via StartTimeTicks — its timeline begins at 0 == that point — so
+    // seeking a stream would jump PAST the content by the handoff position again.
+    if let Some(seek_to) = plan.seek_to {
+        info!(
+            "player_enter_background_audio: seeking the downloaded file to {:.1}s",
+            seek_to
+        );
+        controller.seek(seek_to).map_err(|e| e.to_string())?;
+    }
 
     controller.emit_queue_changed();
     if let Some(emitter) = controller.event_emitter() {
@@ -801,7 +854,14 @@ pub async fn player_exit_background_audio(
     // moment it matters most. Capturing into a `let` before stop() is also the
     // lock discipline from CLAUDE.md: never hold work across a re-entrant call.
     // (DR-159)
-    let absolute = controller.position();
+    //
+    // `absolute_position` rather than `position`, because a tick that has not
+    // landed *yet* is the same hazard from the other side: returning to the
+    // foreground while the audio-only transcode is still opening read 0.0, and
+    // the video reloaded at StartTimeTicks=0 — the episode restarting from the
+    // beginning. Flooring at the handoff base cannot overshoot: the stream is
+    // physically incapable of being behind its own starting point. (DR-178)
+    let absolute = controller.absolute_position();
 
     // Now safe to tear the handoff down, native side first.
     let _ = crate::player::set_lockscreen_position_offset(0.0);
@@ -1846,7 +1906,11 @@ pub(super) fn get_player_status(controller: &PlayerController) -> PlayerStatus {
 
     PlayerStatus {
         state: controller.state(),
-        position: controller.position(),
+        // The position on the item's timeline, whichever of the three paths is
+        // rendering it — the native backend answers for only one of them, and
+        // reads 0 for webview video and for a handoff that has not ticked yet.
+        // TRACES: UR-005 | DR-178
+        position: controller.absolute_position(),
         duration: controller.duration(),
         volume: controller.volume(),
         muted: controller.muted(),
@@ -2838,6 +2902,49 @@ mod tests {
         }
     }
 
+    /// The two sources start in different places, so the handoff cannot treat
+    /// them alike.
+    ///
+    /// An audio-only *stream* is built with `StartTimeTicks`, so the server makes
+    /// the handoff point that stream's zero: the base is the handoff position and
+    /// seeking would jump past the content. A *downloaded file* has no such
+    /// parameter — it starts at the episode's own zero — so basing it at the
+    /// handoff position claims 18 minutes of audio that is about to play from the
+    /// beginning. That is the downloaded-episode version of "it restarts when the
+    /// screen sleeps", and it needs the opposite treatment: no base, and a seek.
+    ///
+    /// TRACES: UR-040, UR-071 | DR-180 | UT-181
+    #[test]
+    fn test_background_audio_plan_seeks_a_file_and_bases_a_stream() {
+        use super::background_audio_plan;
+
+        let local = background_audio_plan(true, 1104.0);
+        assert_eq!(local.base_seconds, 0.0);
+        assert_eq!(local.seek_to, Some(1104.0));
+
+        let streamed = background_audio_plan(false, 1104.0);
+        assert_eq!(streamed.base_seconds, 1104.0);
+        assert_eq!(
+            streamed.seek_to, None,
+            "the URL already starts at the handoff point; seeking again skips past it"
+        );
+    }
+
+    /// Handing off at the very start has nothing to seek to and nothing to base:
+    /// both sources are already where they need to be.
+    ///
+    /// TRACES: UR-040, UR-071 | DR-180 | UT-181
+    #[test]
+    fn test_background_audio_plan_at_the_start_neither_seeks_nor_bases() {
+        use super::background_audio_plan;
+
+        for local in [true, false] {
+            let plan = background_audio_plan(local, 0.0);
+            assert_eq!(plan.base_seconds, 0.0);
+            assert_eq!(plan.seek_to, None);
+        }
+    }
+
     /// A downloaded item must resolve to its file, and a `downloads` row whose
     /// file has gone must resolve to `None` so the caller falls back to
     /// streaming instead of handing the player a path that cannot be opened.
diff --git a/src-tauri/src/player/mod.rs b/src-tauri/src/player/mod.rs
index 2f1ed0ef..5c1497df 100644
--- a/src-tauri/src/player/mod.rs
+++ b/src-tauri/src/player/mod.rs
@@ -55,6 +55,75 @@ pub use android::{
     set_remote_volume_handler, MediaCommandHandler, RemoteVolumeHandler,
 };
 
+/// Where the player's playback reports go.
+///
+/// The controller's side of reporting is "send this, don't make me wait": a slow
+/// or failing sync must never stall playback, so every send is fire-and-forget.
+/// Production wires this to [`PlaybackReporter`] (local DB, server sync, offline
+/// queueing); tests capture the operations instead of standing up a database and
+/// an HTTP client, which is what let the missing reports below be written as
+/// failing tests rather than found on a device.
+///
+/// TRACES: UR-025 | DR-179
+pub trait PlaybackReportSink: Send + Sync {
+    /// Deliver `operation`. Must not block the caller.
+    fn send(&self, operation: PlaybackOperation);
+}
+
+/// The production sink: hands each operation to the `PlaybackReporter`.
+///
+/// Reports originate on whatever thread playback ended or ticked on — including
+/// JNI callbacks with no Tokio runtime attached — so the spawn falls back to a
+/// throwaway runtime on its own thread rather than assuming one is current.
+struct ReporterSink {
+    reporter: Arc<TokioMutex<Option<PlaybackReporter>>>,
+}
+
+impl PlaybackReportSink for ReporterSink {
+    fn send(&self, operation: PlaybackOperation) {
+        let reporter = self.reporter.clone();
+        let task = async move {
+            let guard = reporter.lock().await;
+            let Some(reporter) = guard.as_ref() else {
+                warn!("[PlayerController] PlaybackReporter not initialized; dropping report");
+                return;
+            };
+            // `report` decides local-vs-server and queues for sync itself.
+            if let Err(e) = reporter.report(operation, true).await {
+                log::error!("[PlayerController] Failed to report playback: {}", e);
+            }
+        };
+
+        if let Ok(handle) = tokio::runtime::Handle::try_current() {
+            handle.spawn(task);
+        } else {
+            std::thread::spawn(move || match tokio::runtime::Runtime::new() {
+                Ok(rt) => rt.block_on(task),
+                Err(e) => log::error!(
+                    "[PlayerController] No runtime available to report playback: {}",
+                    e
+                ),
+            });
+        }
+    }
+}
+
+/// The position to report when a stream ends naturally.
+///
+/// The item's runtime when we know it, because the point of the report is to say
+/// the episode *finished* and Jellyfin decides that by percentage — the last
+/// position actually observed can be seconds short, and on a handoff whose ticks
+/// stopped early it can be nowhere near the end. Without a runtime the best
+/// available answer is where playback got to.
+///
+/// TRACES: UR-025, UR-040 | DR-179 | UT-179
+fn completion_report_position(runtime: Option<f64>, last_position: f64) -> f64 {
+    match runtime {
+        Some(runtime) if runtime > 0.0 => runtime,
+        _ => last_position.max(0.0),
+    }
+}
+
 /// Seconds added per attempt before retrying a stream that failed with an error.
 ///
 /// Attempt 1 waits this long, attempt 2 twice as long, and so on — a spread that
@@ -127,6 +196,7 @@ use crate::playback_reporting::{
 };
 use crate::repository::MediaRepository;
 use crate::settings::AudioSettings;
+use crate::utils::conversions::seconds_to_ticks;
 
 /// Central player controller that coordinates playback
 pub struct PlayerController {
@@ -153,9 +223,12 @@ pub struct PlayerController {
     // Playback reporting (dual sync: local DB + server)
     playback_reporter: Arc<TokioMutex<Option<PlaybackReporter>>>,
 
-    // Event throttler to prevent spam from position updates
-    // Will be used when position update hooks are added to backends
-    #[allow(dead_code)]
+    // Where playback reports go. Swappable so tests can assert on what the
+    // player tells Jellyfin. See `PlaybackReportSink`.
+    reports: Arc<Mutex<Arc<dyn PlaybackReportSink>>>,
+
+    // Bounds progress reports to one per item per 30s. Position ticks arrive
+    // four times a second; the server needs a resume point, not a firehose.
     position_throttler: Arc<EventThrottler>,
 
     // End reason tracking for autoplay decision making
@@ -209,6 +282,19 @@ pub struct PlayerController {
     // competing intents to take opposing actions. `None` means no webview media
     // is active and the native backend is authoritative. See DR-097.
     html5_playing: Arc<Mutex<Option<bool>>>,
+
+    // Last position/duration reported by webview-rendered media.
+    //
+    // On the webview path the `<video>` element IS the player: nothing is loaded
+    // into the native backend, so `backend.position()` is a permanent 0. Those
+    // reports used to be re-emitted to the frontend and then dropped, which is
+    // why every position the *backend* sent to Jellyfin — including the stop
+    // report that sets the resume point — was zero, overwriting the correct one
+    // the frontend had just sent. Storing them here makes
+    // `absolute_position()` answer for both rendering paths.
+    //
+    // TRACES: UR-005, UR-025 | DR-178
+    reported_time: Arc<Mutex<stream_end::ObservedTime>>,
 }
 
 impl PlayerController {
@@ -217,6 +303,9 @@ impl PlayerController {
         playback_reporter: Arc<TokioMutex<Option<PlaybackReporter>>>,
         position_throttler: Arc<EventThrottler>,
     ) -> Self {
+        let reports: Arc<dyn PlaybackReportSink> = Arc::new(ReporterSink {
+            reporter: playback_reporter.clone(),
+        });
         let controller = Self {
             backend: Arc::new(Mutex::new(backend)),
             queue: Arc::new(Mutex::new(QueueManager::new())),
@@ -228,6 +317,7 @@ impl PlayerController {
             event_emitter: Arc::new(Mutex::new(None)),
             countdown_cancel: Arc::new(Mutex::new(None)),
             playback_reporter,
+            reports: Arc::new(Mutex::new(reports)),
             position_throttler,
             end_reason: Arc::new(Mutex::new(None)),
             autoplay_episode_count: Arc::new(Mutex::new(0)),
@@ -235,6 +325,7 @@ impl PlayerController {
             background_audio_active: Arc::new(Mutex::new(false)),
             stream_resume: Arc::new(Mutex::new(stream_end::ResumeTracker::default())),
             html5_playing: Arc::new(Mutex::new(None)),
+            reported_time: Arc::new(Mutex::new(stream_end::ObservedTime::default())),
         };
 
         // Start background timer thread for sleep timer countdown
@@ -394,6 +485,12 @@ impl PlayerController {
         );
 
         self.reset_autoplay_count();
+        // A different item is current; the last one's reported position must not
+        // be reported against it. This path is how webview-rendered video is
+        // queued (no backend load at all), so it is exactly where a stale
+        // reading would otherwise survive.
+        // TRACES: UR-005 | DR-178
+        self.clear_reported_time();
 
         let mut queue = self.queue.lock_safe();
         queue.set_queue(vec![item], 0);
@@ -414,11 +511,12 @@ impl PlayerController {
         backend.play()?;
         drop(backend);
 
+        // A different item is loading; the last one's reported position must not
+        // be attributed to it.
+        self.clear_reported_time();
+
         // Report playback start using PlaybackReporter (dual sync: local DB + server)
         if let Some(jellyfin_id) = item.jellyfin_id() {
-            let jellyfin_id = jellyfin_id.to_string();
-            let reporter = self.playback_reporter.clone();
-
             // Build playback context from item metadata
             let context = if item.album_id.is_some() {
                 Some(PlaybackContext {
@@ -429,53 +527,23 @@ impl PlayerController {
                 None
             };
 
-            // Spawn on Tokio runtime if available, otherwise use a new thread
-            if let Ok(handle) = tokio::runtime::Handle::try_current() {
-                handle.spawn(async move {
-                    let reporter_guard = reporter.lock().await;
-                    if let Some(reporter_instance) = reporter_guard.as_ref() {
-                        log::info!("[PlayerController] Reporting playback start via PlaybackReporter: {}", jellyfin_id);
+            // Where this stream actually begins. Zero for an ordinary load, but a
+            // background-audio handoff loads a stream whose zero is the handoff
+            // point — telling the server the session started at 0:00 there both
+            // misreports the session and, being a position, competes with the
+            // real one.
+            let position = self.absolute_position();
 
-                        let operation = PlaybackOperation::Start {
-                            item_id: jellyfin_id.clone(),
-                            position_ticks: 0,
-                            context,
-                        };
-
-                        // Note: PlaybackReporter internally checks connectivity
-                        // We pass is_online=true as default; reporter will check actual status
-                        match reporter_instance.report(operation, true).await {
-                            Ok(_) => log::info!("[PlayerController] Successfully reported playback start (local DB + server sync)"),
-                            Err(e) => log::error!("[PlayerController] Failed to report playback start: {}", e),
-                        }
-                    } else {
-                        log::warn!("[PlayerController] PlaybackReporter not initialized - using fallback JellyfinClient");
-                        // Fallback to legacy JellyfinClient (will be removed after full migration)
-                    }
-                });
-            } else {
-                // Fallback: spawn in a new thread with its own runtime
-                std::thread::spawn(move || {
-                    let rt = tokio::runtime::Runtime::new().unwrap();
-                    rt.block_on(async move {
-                        let reporter_guard = reporter.lock().await;
-                        if let Some(reporter_instance) = reporter_guard.as_ref() {
-                            log::info!("[PlayerController] Reporting playback start via PlaybackReporter: {}", jellyfin_id);
-
-                            let operation = PlaybackOperation::Start {
-                                item_id: jellyfin_id.clone(),
-                                position_ticks: 0,
-                                context,
-                            };
-
-                            match reporter_instance.report(operation, true).await {
-                                Ok(_) => log::info!("[PlayerController] Successfully reported playback start"),
-                                Err(e) => log::error!("[PlayerController] Failed to report playback start: {}", e),
-                            }
-                        }
-                    });
-                });
-            }
+            log::info!(
+                "[PlayerController] Reporting playback start: {} @ {:.1}s",
+                jellyfin_id,
+                position
+            );
+            self.report(PlaybackOperation::Start {
+                item_id: jellyfin_id.to_string(),
+                position_ticks: seconds_to_ticks(position),
+                context,
+            });
         }
 
         Ok(())
@@ -634,66 +702,56 @@ impl PlayerController {
                 .and_then(|item| item.jellyfin_id().map(|s| s.to_string()))
         };
 
-        let position_ticks = {
-            let backend = self.backend.lock_safe();
-            (backend.position() * 10_000_000.0) as i64
-        };
+        // Read across every rendering path BEFORE stopping: the backend zeroes
+        // its position on stop, and the element that was reporting is gone.
+        let position = self.absolute_position();
 
         let mut backend = self.backend.lock_safe();
         backend.stop()?;
         drop(backend);
+        self.clear_reported_time();
 
-        // Report playback stopped using PlaybackReporter (dual sync: local DB + server)
         if let Some(jellyfin_id) = jellyfin_id {
-            let reporter = self.playback_reporter.clone();
-
-            // Spawn on Tokio runtime if available, otherwise use a new thread
-            if let Ok(handle) = tokio::runtime::Handle::try_current() {
-                handle.spawn(async move {
-                    let reporter_guard = reporter.lock().await;
-                    if let Some(reporter_instance) = reporter_guard.as_ref() {
-                        log::info!("[PlayerController] Reporting playback stopped via PlaybackReporter: {}", jellyfin_id);
-
-                        let operation = PlaybackOperation::Stopped {
-                            item_id: jellyfin_id.clone(),
-                            position_ticks,
-                        };
-
-                        match reporter_instance.report(operation, true).await {
-                            Ok(_) => log::info!("[PlayerController] Successfully reported playback stopped (local DB + server sync)"),
-                            Err(e) => log::error!("[PlayerController] Failed to report playback stopped: {}", e),
-                        }
-                    } else {
-                        log::warn!("[PlayerController] PlaybackReporter not initialized");
-                    }
-                });
-            } else {
-                // Fallback: spawn in a new thread with its own runtime
-                std::thread::spawn(move || {
-                    let rt = tokio::runtime::Runtime::new().unwrap();
-                    rt.block_on(async move {
-                        let reporter_guard = reporter.lock().await;
-                        if let Some(reporter_instance) = reporter_guard.as_ref() {
-                            log::info!("[PlayerController] Reporting playback stopped via PlaybackReporter: {}", jellyfin_id);
-
-                            let operation = PlaybackOperation::Stopped {
-                                item_id: jellyfin_id.clone(),
-                                position_ticks,
-                            };
-
-                            match reporter_instance.report(operation, true).await {
-                                Ok(_) => log::info!("[PlayerController] Successfully reported playback stopped"),
-                                Err(e) => log::error!("[PlayerController] Failed to report playback stopped: {}", e),
-                            }
-                        }
-                    });
-                });
-            }
+            self.report_stopped_at(jellyfin_id, position);
         }
 
         Ok(())
     }
 
+    /// Tell Jellyfin playback stopped at `position`, unless that position is
+    /// zero.
+    ///
+    /// Jellyfin stores the reported position as the resume point, so a zero is
+    /// not a harmless no-op — it is an instruction to forget where the viewer
+    /// was. And it is never *information*: nobody watched zero seconds of
+    /// anything, so every zero this app ever sent came from asking a player that
+    /// was not rendering the media (webview video, or a handoff whose first tick
+    /// had not landed). On a device trace, 14 of 14 stop reports in 35 minutes
+    /// were zeroes, one of them 40s after the frontend had correctly reported
+    /// 15:22 for the same episode.
+    ///
+    /// TRACES: UR-025, UR-005 | DR-179 | UT-178
+    fn report_stopped_at(&self, jellyfin_id: String, position: f64) {
+        if position <= 0.0 {
+            debug!(
+                "[PlayerController] Withholding zero-position stop report for {} \
+                 (nothing played; reporting it would clear the resume point)",
+                jellyfin_id
+            );
+            return;
+        }
+
+        log::info!(
+            "[PlayerController] Reporting playback stopped: {} @ {:.1}s",
+            jellyfin_id,
+            position
+        );
+        self.report(PlaybackOperation::Stopped {
+            item_id: jellyfin_id,
+            position_ticks: seconds_to_ticks(position),
+        });
+    }
+
     /// Skip to next track
     ///
     /// Note: load_and_play sets EndReason::NewTrackLoaded to prevent autoplay
@@ -783,11 +841,18 @@ impl PlayerController {
     ///
     /// TRACES: UR-040, UR-005 | DR-159 | UT-155
     pub async fn seek_absolute(&self, position: f64) -> Result<(), String> {
+        // Only a *streamed* handoff needs the rebuild. A downloaded file seeks
+        // like any other file — and `resume_stream_at` refuses a non-remote
+        // source, so sending one through here fails the seek outright.
+        // TRACES: UR-071 | DR-180 | UT-181
         let rebuild = self.is_background_audio_active() && {
             let queue = self.queue.lock_safe();
             queue
                 .current()
-                .map(Self::is_audio_only_video)
+                .map(|item| {
+                    Self::is_audio_only_video(item)
+                        && matches!(item.source, MediaSource::Remote { .. })
+                })
                 .unwrap_or(false)
         };
 
@@ -825,9 +890,97 @@ impl PlayerController {
         self.backend.lock_safe().position()
     }
 
-    /// Get duration
+    /// The position on the **item's own timeline**, whatever is rendering it.
+    ///
+    /// This is what every outbound position must be taken from — the resume point
+    /// sent to Jellyfin, the point the video reloads at when a handoff ends, the
+    /// truncation comparison. `position()` alone answers for exactly one of the
+    /// three ways this app plays media, and reads 0 for the other two:
+    ///
+    /// - **Webview `<video>`/`<audio>`**: nothing is loaded into the native
+    ///   backend, so its position is a permanent 0. The element's own reports are
+    ///   the only reading there is.
+    /// - **Background-audio handoff**: the audio-only stream's zero is the
+    ///   handoff point, and the base is added at the native tick boundary
+    ///   (DR-159) — so before the first tick lands, nothing has applied it.
+    ///   Flooring at the base is exact rather than approximate: the stream cannot
+    ///   physically be behind its own starting point.
+    /// - **Native playback**: the backend is authoritative and both other terms
+    ///   are zero, so the max is its own value.
+    ///
+    /// Returning to the foreground during that pre-first-tick window is what
+    /// restarted an episode from 0:00 and wiped its server-side resume point.
+    ///
+    /// TRACES: UR-040, UR-005, UR-025 | DR-178 | UT-176, UT-177
+    pub fn absolute_position(&self) -> f64 {
+        let native = self.backend.lock_safe().position().max(0.0);
+        let reported = self.reported_time.lock_safe().last_position();
+        let base = if self.is_background_audio_active() {
+            *self.background_audio_base.lock_safe()
+        } else {
+            0.0
+        };
+
+        native.max(reported).max(base)
+    }
+
+    /// The duration last reported by webview-rendered media, if any.
+    ///
+    /// TRACES: UR-005 | DR-178 | UT-177
+    pub fn observed_duration(&self) -> Option<f64> {
+        self.reported_time.lock_safe().last_duration()
+    }
+
+    /// Forget what webview-rendered media reported.
+    ///
+    /// Called wherever that element stops being the player — it was torn down,
+    /// a handoff took over, or a different item is loading. A stale position
+    /// outliving its element would be reported against whatever plays next.
+    ///
+    /// TRACES: UR-005 | DR-178 | UT-177
+    fn clear_reported_time(&self) {
+        self.reported_time.lock_safe().reset();
+    }
+
+    /// Replace the sink playback reports go to. Tests capture; production wires
+    /// the `PlaybackReporter` at construction and never swaps it.
+    ///
+    /// TRACES: UR-025 | DR-179
+    #[cfg_attr(not(test), allow(dead_code))]
+    pub fn set_report_sink(&self, sink: Arc<dyn PlaybackReportSink>) {
+        *self.reports.lock_safe() = sink;
+    }
+
+    /// Send a playback report. Fire-and-forget by contract, so callers can do
+    /// this while holding nothing and waiting for nothing.
+    ///
+    /// TRACES: UR-025 | DR-179
+    fn report(&self, operation: PlaybackOperation) {
+        let sink = self.reports.lock_safe().clone();
+        sink.send(operation);
+    }
+
+    /// The Jellyfin id of whatever is currently queued, if it has one.
+    fn current_jellyfin_id(&self) -> Option<String> {
+        let queue = self.queue.lock_safe();
+        queue
+            .current()
+            .and_then(|item| item.jellyfin_id().map(|id| id.to_string()))
+    }
+
+    /// Get duration.
+    ///
+    /// Falls back to what webview-rendered media reported for the same reason
+    /// [`absolute_position`](Self::absolute_position) does: on that path nothing
+    /// is loaded into the native backend, so its duration is `None` and the
+    /// element's report is the only one there is.
+    ///
+    /// TRACES: UR-005 | DR-178
     pub fn duration(&self) -> Option<f64> {
-        self.backend.lock_safe().duration()
+        self.backend
+            .lock_safe()
+            .duration()
+            .or_else(|| self.observed_duration())
     }
 
     /// Get queue reference
@@ -1063,7 +1216,7 @@ impl PlayerController {
         // "stopped"/"idle" mean the element is gone, so hand authority back to
         // the native backend — otherwise music playback would keep emitting
         // ControlCommands at a element that no longer exists.
-        {
+        let element_gone = {
             let mut tracked = self.html5_playing.lock_safe();
             *tracked = match state.as_str() {
                 "playing" => Some(true),
@@ -1074,6 +1227,12 @@ impl PlayerController {
                 // "stopped"/"idle": element is gone, native backend resumes authority.
                 _ => None,
             };
+            tracked.is_none()
+        };
+        // Its last position goes with it: whatever plays next is loaded into the
+        // native backend, and a stale reading would be reported against that.
+        if element_gone {
+            self.clear_reported_time();
         }
         if let Some(emitter) = self.event_emitter.lock_safe().as_ref() {
             emitter.emit(PlayerStatusEvent::StateChanged { state, media_id });
@@ -1090,9 +1249,50 @@ impl PlayerController {
         if self.is_background_audio_active() {
             return;
         }
+        // The element is the player on this path, so this tick is the position —
+        // for the resume point, the stop report and everything else that asks.
+        self.reported_time.lock_safe().record(position, duration);
+
         if let Some(emitter) = self.event_emitter.lock_safe().as_ref() {
             emitter.emit(PlayerStatusEvent::PositionUpdate { position, duration });
         }
+
+        self.report_progress_throttled(position);
+    }
+
+    /// Send a throttled progress report to Jellyfin.
+    ///
+    /// Progress is what makes a position survive anything other than a clean
+    /// exit — a crash, a swipe-away, a battery death — and lets another device
+    /// resume mid-episode. Webview-rendered media reported none: the frontend
+    /// service writes progress to the local DB only, and Rust had no position
+    /// for it to report. A device trace covering 35 minutes of playback hit
+    /// `/Sessions/Playing/Progress` exactly zero times.
+    ///
+    /// The throttler is the one the controller already owned for this purpose
+    /// (30s per item), so ticks arriving four times a second cost one request
+    /// per half-minute.
+    ///
+    /// TRACES: UR-005, UR-025 | DR-179 | UT-180
+    fn report_progress_throttled(&self, position: f64) {
+        if position <= 0.0 {
+            return;
+        }
+        let Some(item_id) = self.current_jellyfin_id() else {
+            return;
+        };
+        if !self.position_throttler.should_report(&item_id) {
+            return;
+        }
+
+        self.report(PlaybackOperation::Progress {
+            item_id: item_id.clone(),
+            position_ticks: seconds_to_ticks(position),
+            // Ticks only arrive while the element is playing; a pause is carried
+            // by the state report, not by a position that stopped moving.
+            is_paused: false,
+        });
+        self.position_throttler.mark_reported(&item_id);
     }
 
     /// Report that the HTML5 <video> element finished loading and knows its
@@ -1186,6 +1386,11 @@ impl PlayerController {
             return Ok(AutoplayDecision::Stop);
         };
 
+        // The item is genuinely finished (a truncated stream returned above), so
+        // report it before anything advances — after an advance the queue's
+        // current item is the *next* episode and this one is unreachable.
+        self.report_completion(&current);
+
         // Check sleep timer state
         let timer_mode = {
             let timer = self.sleep_timer.lock_safe();
@@ -1293,6 +1498,43 @@ impl PlayerController {
         }
     }
 
+    /// Report an item that just finished as stopped at its runtime, so Jellyfin
+    /// marks it played.
+    ///
+    /// Jellyfin decides "watched" from the `PlaybackStopped` report and its
+    /// position — no report, no completion, however much of the episode was
+    /// actually heard. In the foreground the frontend sends one when the
+    /// `<video>` ends. In background audio-only mode there is nobody: the webview
+    /// is suspended and its element was torn down at the handoff, while the
+    /// backend drove the advance to the next episode and said nothing about the
+    /// one that ended. An episode listened to end-to-end on the lockscreen
+    /// therefore never counted, and (before DR-179) was often reset to 0 by the
+    /// stop report that followed.
+    ///
+    /// Scoped to the audio-only handoff — the case the frontend provably cannot
+    /// report — so foreground playback keeps its single existing report rather
+    /// than gaining a second one. Music tracks ending natively remain
+    /// unreported; that is the same gap through a different door and wants its
+    /// own change.
+    ///
+    /// TRACES: UR-040, UR-025 | DR-179 | UT-179
+    fn report_completion(&self, item: &MediaItem) {
+        if !Self::is_audio_only_video(item) {
+            return;
+        }
+        let Some(jellyfin_id) = item.jellyfin_id().map(|id| id.to_string()) else {
+            return;
+        };
+
+        let position = completion_report_position(item.duration, self.absolute_position());
+        log::info!(
+            "[PlayerController] Audio-only {} finished — reporting complete at {:.1}s",
+            jellyfin_id,
+            position
+        );
+        self.report_stopped_at(jellyfin_id, position);
+    }
+
     /// Record the base offset of a background-audio handoff (the position the
     /// video was handed off at, which is the audio stream's zero).
     ///
@@ -1315,6 +1557,9 @@ impl PlayerController {
         self.set_background_audio_base(position);
         *self.background_audio_active.lock_safe() = true;
         *self.html5_playing.lock_safe() = None;
+        // The element is being torn down; its last position describes a video
+        // that is no longer playing, and the base describes the one that is.
+        self.clear_reported_time();
     }
 
     /// Leave a background-audio handoff, returning the base offset to add to the
@@ -1422,10 +1667,11 @@ impl PlayerController {
             return None;
         }
 
-        // Already absolute: the Android position tick shifts by the handoff base
-        // before anything sees the value, so adding it again here would
-        // double-count it. (DR-159)
-        let absolute = self.position().max(0.0);
+        // The Android position tick shifts by the handoff base before anything
+        // sees the value, so adding it again here would double-count it
+        // (DR-159) — `absolute_position` floors at the base instead, which is
+        // what a stream that died before its first tick needs. (DR-178)
+        let absolute = self.absolute_position();
 
         match self.stream_resume.lock_safe().allow_attempt(absolute) {
             Some(attempt) => Some((absolute, attempt)),
@@ -1938,6 +2184,57 @@ mod tests {
         }
     }
 
+    /// Captures what the controller reports to Jellyfin, so tests can assert on
+    /// the operations themselves rather than on a database and an HTTP client.
+    struct CapturingReports {
+        operations: std::sync::Mutex<Vec<PlaybackOperation>>,
+    }
+
+    impl CapturingReports {
+        fn new() -> Self {
+            Self {
+                operations: std::sync::Mutex::new(Vec::new()),
+            }
+        }
+
+        /// Every `Stopped` report as `(item_id, position_seconds)`.
+        fn stops(&self) -> Vec<(String, f64)> {
+            self.operations
+                .lock_safe()
+                .iter()
+                .filter_map(|op| match op {
+                    PlaybackOperation::Stopped {
+                        item_id,
+                        position_ticks,
+                    } => Some((item_id.clone(), *position_ticks as f64 / 10_000_000.0)),
+                    _ => None,
+                })
+                .collect()
+        }
+
+        /// Every `Progress` report as `(item_id, position_seconds)`.
+        fn progress(&self) -> Vec<(String, f64)> {
+            self.operations
+                .lock_safe()
+                .iter()
+                .filter_map(|op| match op {
+                    PlaybackOperation::Progress {
+                        item_id,
+                        position_ticks,
+                        ..
+                    } => Some((item_id.clone(), *position_ticks as f64 / 10_000_000.0)),
+                    _ => None,
+                })
+                .collect()
+        }
+    }
+
+    impl PlaybackReportSink for CapturingReports {
+        fn send(&self, operation: PlaybackOperation) {
+            self.operations.lock_safe().push(operation);
+        }
+    }
+
     #[test]
     fn test_report_html5_state_emits_state_changed() {
         let controller = PlayerController::default();
@@ -3613,6 +3910,39 @@ mod tests {
         }
     }
 
+    /// The same episode handed off from a **downloaded file** — the handoff's
+    /// other source, which starts at the episode's own zero rather than at the
+    /// handoff point.
+    fn local_audio_only_episode(runtime_seconds: f64) -> MediaItem {
+        MediaItem {
+            source: MediaSource::Local {
+                file_path: std::path::PathBuf::from("/downloads/ep2.mkv"),
+                jellyfin_item_id: Some("ep2".to_string()),
+            },
+            ..audio_only_episode(runtime_seconds)
+        }
+    }
+
+    /// A file seeks like a file. The rebuild path exists because a chunked
+    /// length-less transcode cannot honour a seek, which is not true of local
+    /// media — and `resume_stream_at` refuses a non-remote source outright, so
+    /// routing a lockscreen scrub through it fails the seek instead of doing it.
+    ///
+    /// TRACES: UR-040, UR-071 | DR-180 | UT-181
+    #[tokio::test]
+    async fn test_seek_absolute_on_a_downloaded_handoff_is_an_ordinary_seek() {
+        let controller = PlayerController::default();
+        controller
+            .play_queue(vec![local_audio_only_episode(1500.0)], 0)
+            .unwrap();
+        // A downloaded handoff claims no base: the file's zero is the episode's.
+        controller.enter_background_audio(0.0);
+
+        controller.seek_absolute(900.0).await.unwrap();
+
+        assert_eq!(controller.position(), 900.0);
+    }
+
     /// A flaky connection truncates the progressive mp3 transcode that carries
     /// background audio-only playback. ExoPlayer sees end-of-input on a stream
     /// with no reliable length, so it reports STATE_ENDED ten minutes into a
@@ -3723,6 +4053,272 @@ mod tests {
         );
     }
 
+    // ===== Position authority and reporting (DR-178, DR-179) =====
+    //
+    // Every position that leaves the app — the resume point Jellyfin stores, the
+    // point the video reloads at on the way back from a handoff, the truncation
+    // maths — is read off the controller. The device trace showed all of them
+    // reading 0: the native backend is not the player on the webview path, and
+    // during a handoff its base is only applied once ExoPlayer has ticked, which
+    // it has not while the audio-only transcode is still opening.
+
+    /// Returning to the foreground before the audio-only stream has started
+    /// playing hands back the handoff's own starting point, never zero.
+    ///
+    /// Observed on device: locked at 18.4s, unlocked 3.5s later with ExoPlayer
+    /// still `IDLE`, `player_exit_background_audio` returned `0.0`, and the video
+    /// reloaded with `StartTimeTicks=0` — the episode restarted from the
+    /// beginning, and the `Stopped` report that followed wiped the server's
+    /// resume point too.
+    ///
+    /// TRACES: UR-040 | DR-178 | UT-176
+    #[test]
+    fn test_absolute_position_floors_at_the_handoff_base() {
+        let controller = PlayerController::default();
+        controller.enter_background_audio(18.4);
+
+        // No tick has landed, so nothing has applied the base yet.
+        assert_eq!(controller.position(), 0.0);
+        assert_eq!(
+            controller.absolute_position(),
+            18.4,
+            "the audio stream's zero IS the handoff point, so the position can \
+             never legitimately read below it"
+        );
+    }
+
+    /// Once ticks are flowing the base has already been applied at the native
+    /// boundary (DR-159), so flooring must not add it a second time.
+    ///
+    /// TRACES: UR-040 | DR-178 | UT-176
+    #[test]
+    fn test_absolute_position_does_not_double_count_the_handoff_base() {
+        let controller = PlayerController::default();
+        controller.enter_background_audio(18.4);
+
+        // What the real backend reports after a tick: already absolute.
+        controller.seek(120.0).unwrap();
+
+        assert_eq!(controller.absolute_position(), 120.0);
+    }
+
+    /// On the webview path the `<video>` element is the player and the native
+    /// backend holds nothing, so the position it reports is the only one there
+    /// is. It used to be re-emitted to the frontend and then dropped, leaving
+    /// every backend-side report at 0.
+    ///
+    /// TRACES: UR-005, UR-025 | DR-178 | UT-177
+    #[test]
+    fn test_webview_position_reports_become_the_controllers_position() {
+        let controller = PlayerController::default();
+
+        controller.report_html5_position(253.4, 2640.0);
+
+        assert_eq!(controller.absolute_position(), 253.4);
+        assert_eq!(controller.observed_duration(), Some(2640.0));
+    }
+
+    /// A torn-down element's last position must not outlive it: the next thing
+    /// to play is loaded into the native backend, and a stale 253s would be
+    /// reported against it.
+    ///
+    /// TRACES: UR-005 | DR-178 | UT-177
+    #[test]
+    fn test_webview_teardown_clears_the_observed_position() {
+        let controller = PlayerController::default();
+        controller.report_html5_position(253.4, 2640.0);
+
+        controller.report_html5_state("stopped".to_string(), None);
+
+        assert_eq!(controller.absolute_position(), 0.0);
+    }
+
+    /// Entering a handoff tears the element down, so its position stops being
+    /// the answer at that exact moment — the native audio player's does.
+    ///
+    /// TRACES: UR-040 | DR-178 | UT-177
+    #[test]
+    fn test_entering_a_handoff_drops_the_torn_down_elements_position() {
+        let controller = PlayerController::default();
+        controller.report_html5_position(253.4, 2640.0);
+
+        controller.enter_background_audio(18.4);
+
+        assert_eq!(
+            controller.absolute_position(),
+            18.4,
+            "the video element is gone; only the handoff base describes the \
+             stream that is now playing"
+        );
+    }
+
+    /// Nobody ever watched zero seconds of anything. A `Stopped` at 0 carries no
+    /// information and Jellyfin stores it as the resume point, so the only thing
+    /// it can do is destroy one — which is what the device trace caught it doing
+    /// 14 times in 35 minutes, including 40s after the frontend had correctly
+    /// reported 922s for the same episode.
+    ///
+    /// TRACES: UR-025 | DR-179 | UT-178
+    #[tokio::test]
+    async fn test_a_stop_at_zero_is_never_reported() {
+        let controller = PlayerController::default();
+        let reports = Arc::new(CapturingReports::new());
+        controller.set_report_sink(reports.clone());
+        controller
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+
+        // Nothing ever played: the backend is at 0 and no element reported in.
+        controller.stop().unwrap();
+
+        assert!(
+            reports.stops().is_empty(),
+            "a zero-position stop must be withheld, not sent; got {:?}",
+            reports.stops()
+        );
+    }
+
+    /// A real position is still reported, so withholding zero cannot be
+    /// mistaken for withholding everything — from either rendering path.
+    ///
+    /// The webview half is the one that was broken: the element reports 253s, the
+    /// native backend holds nothing, and the stop report went out as 0 and
+    /// overwrote the resume point the frontend had just written correctly.
+    ///
+    /// TRACES: UR-025 | DR-178, DR-179 | UT-178
+    #[tokio::test]
+    async fn test_a_stop_reports_the_position_actually_reached() {
+        // Webview-rendered: the element is the only thing that knows.
+        let webview = PlayerController::default();
+        let webview_reports = Arc::new(CapturingReports::new());
+        webview.set_report_sink(webview_reports.clone());
+        webview
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+        webview.report_html5_position(253.0, 1500.0);
+
+        webview.stop().unwrap();
+
+        assert_eq!(webview_reports.stops(), vec![("ep2".to_string(), 253.0)]);
+
+        // Natively rendered: the backend is authoritative and still is.
+        let native = PlayerController::default();
+        let native_reports = Arc::new(CapturingReports::new());
+        native.set_report_sink(native_reports.clone());
+        native
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+        native.seek(253.0).unwrap();
+
+        native.stop().unwrap();
+
+        assert_eq!(native_reports.stops(), vec![("ep2".to_string(), 253.0)]);
+    }
+
+    /// An episode listened to end-to-end on the lockscreen must count as
+    /// watched. Jellyfin decides that on the `PlaybackStopped` report — no
+    /// report, no completion — and in background audio-only mode there is
+    /// nobody else to send one: the webview is suspended and its `<video>` was
+    /// torn down at the handoff, so the frontend's end-of-playback reporting
+    /// cannot run. The backend advanced to the next episode and said nothing
+    /// about the one that finished.
+    ///
+    /// TRACES: UR-040, UR-025 | DR-179 | UT-179
+    #[tokio::test]
+    async fn test_a_finished_audio_only_episode_is_reported_complete() {
+        let controller = PlayerController::default();
+        let reports = Arc::new(CapturingReports::new());
+        controller.set_report_sink(reports.clone());
+        controller.set_repository(Arc::new(MockEpisodeRepo::season(3)));
+        controller
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+        // Played out to the end of the 25-minute episode.
+        controller.seek(1499.0).unwrap();
+        controller.take_end_reason();
+
+        controller.on_playback_ended().await.unwrap();
+
+        assert_eq!(
+            reports.stops(),
+            vec![("ep2".to_string(), 1500.0)],
+            "the finished episode must be reported stopped at its runtime, or \
+             Jellyfin's ≥90% rule never marks it played"
+        );
+    }
+
+    /// The completion report is for ends that are really ends. A truncated
+    /// stream is about to be re-opened and the episode is nowhere near over, so
+    /// reporting it stopped would tell Jellyfin the opposite of the truth.
+    ///
+    /// TRACES: UR-040, UR-025 | DR-179 | UT-179
+    #[tokio::test]
+    async fn test_a_truncated_stream_reports_no_completion() {
+        let controller = PlayerController::default();
+        let reports = Arc::new(CapturingReports::new());
+        controller.set_report_sink(reports.clone());
+        controller.set_repository(Arc::new(MockEpisodeRepo::season(3)));
+        controller
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+        controller.seek(600.0).unwrap();
+        controller.take_end_reason();
+
+        let decision = controller.on_playback_ended().await.unwrap();
+
+        assert!(matches!(decision, AutoplayDecision::ResumeStream { .. }));
+        assert!(
+            reports.stops().is_empty(),
+            "a dropped connection is not a finished episode; got {:?}",
+            reports.stops()
+        );
+    }
+
+    /// Position ticks reach Jellyfin while playback is still going, so closing
+    /// the app — or losing it to a crash — cannot cost the whole session. The
+    /// device trace requested `/Sessions/Playing/Progress` exactly zero times in
+    /// 35 minutes: the frontend service writes progress to the local DB only,
+    /// and nothing on the Rust side reported it for webview-rendered media.
+    ///
+    /// TRACES: UR-005, UR-025 | DR-179 | UT-180
+    #[tokio::test]
+    async fn test_webview_position_ticks_report_progress_to_the_server() {
+        let controller = PlayerController::default();
+        let reports = Arc::new(CapturingReports::new());
+        controller.set_report_sink(reports.clone());
+        controller
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+
+        controller.report_html5_position(253.4, 1500.0);
+
+        assert_eq!(reports.progress(), vec![("ep2".to_string(), 253.4)]);
+    }
+
+    /// Ticks arrive four times a second; reports must not. The throttler the
+    /// controller already owns bounds them to one per item per 30s.
+    ///
+    /// TRACES: UR-005 | DR-179 | UT-180
+    #[tokio::test]
+    async fn test_progress_reports_are_throttled_not_sent_per_tick() {
+        let controller = PlayerController::default();
+        let reports = Arc::new(CapturingReports::new());
+        controller.set_report_sink(reports.clone());
+        controller
+            .play_queue(vec![audio_only_episode(1500.0)], 0)
+            .unwrap();
+
+        for tick in 0..12 {
+            controller.report_html5_position(250.0 + tick as f64 * 0.25, 1500.0);
+        }
+
+        assert_eq!(
+            reports.progress().len(),
+            1,
+            "twelve ticks inside one throttle window are one report"
+        );
+    }
+
     /// The truncation check compares the position against the item's runtime, so
     /// both must be on the same timeline.
     ///
diff --git a/src-tauri/src/player/stream_end.rs b/src-tauri/src/player/stream_end.rs
index 40f83446..35987f07 100644
--- a/src-tauri/src/player/stream_end.rs
+++ b/src-tauri/src/player/stream_end.rs
@@ -144,6 +144,18 @@ impl ObservedTime {
         live.filter(|p| *p >= 0.0).unwrap_or(self.position)
     }
 
+    /// The last observed position, with no live reading to prefer — the case
+    /// where the *reporter* is the only source there is (webview-rendered media,
+    /// which the native backend cannot see at all).
+    pub fn last_position(&self) -> f64 {
+        self.position
+    }
+
+    /// The last observed duration, if one was ever established.
+    pub fn last_duration(&self) -> Option<f64> {
+        self.duration
+    }
+
     /// The live reading if there is one, else the last observed value.
     pub fn duration_or_last(&self, live: Option<f64>) -> Option<f64> {
         live.filter(|d| *d > 0.0).or(self.duration)
diff --git a/src/lib/services/playbackReporting.ts b/src/lib/services/playbackReporting.ts
index 7ed72764..1124e34e 100644
--- a/src/lib/services/playbackReporting.ts
+++ b/src/lib/services/playbackReporting.ts
@@ -13,12 +13,15 @@ import { commands } from "$lib/api/bindings";
 import { auth } from "$lib/stores/auth";
 
 /**
- * Report playback start to Jellyfin (or queue if offline)
+ * Record the start of playback **locally**, with the context it started from.
  *
- * The Rust backend handles both local DB updates and server reporting,
- * automatically queueing for sync if the server is unreachable.
+ * The server is told by Rust: loading an item into the controller reports the
+ * start, carrying the position the stream actually begins at (zero for an
+ * ordinary play, the handoff point for a background-audio stream). What this
+ * adds is the context — which album or series the play came from — which only
+ * the local DB keeps.
  *
- * TRACES: UR-005, UR-025 | DR-028
+ * TRACES: UR-005, UR-025 | DR-028, DR-179
  */
 export async function reportPlaybackStart(
   itemId: string,
@@ -50,12 +53,18 @@ export async function reportPlaybackStart(
 }
 
 /**
- * Report playback progress to Jellyfin (or queue if offline)
+ * Record playback progress **locally**.
  *
- * Note: Progress reports are frequent and are not queued for sync.
- * The final position is captured by reportPlaybackStopped.
+ * The server's copy is not sent from here. Position ticks already flow into Rust
+ * through the player adapter (`player_report_position`), and the controller
+ * reports them onward on a 30s throttle — one place that covers webview video,
+ * native audio and the background-audio handoff alike, instead of a second
+ * frequent IPC path racing it.
  *
- * TRACES: UR-005 | DR-028
+ * This function is therefore the *local* half only, which is what its caller
+ * needs for resume points that work offline.
+ *
+ * TRACES: UR-005 | DR-028, DR-179
  */
 export async function reportPlaybackProgress(
   itemId: string,