fix: keep seek target visible until acknowledged and make volume thumb opaque

Checks/playback.mm

@@ -69,22 +69,33 @@ int main(int argc, char **argv) {
                     "pause freezes authoritative position");
             uint64_t revision = paused.revision;
             require(player_seek(player.get(), 1.5), "paused seek accepted");
+            auto pending = player_get_state(player.get());
+            require(pending.seek_pending || std::abs(pending.position - 1.5) < .03,
+                    "accepted seek reports pending until the target is authoritative");
             auto sought = until(player.get(), [revision](auto s) {
-                return s.revision != revision && s.status == PLAYER_PAUSED && std::abs(s.position - 1.5) < .03;
+                return !s.seek_pending && s.revision != revision && s.status == PLAYER_PAUSED && std::abs(s.position - 1.5) < .03;
             });
             [view draw];
             require(sought.status == PLAYER_PAUSED, "seek preserves paused state");
+            require(player_seek(player.get(), .8) && player_seek(player.get(), 1.5), "queued seeks accepted");
+            pending = player_get_state(player.get());
+            require(pending.seek_pending || std::abs(pending.position - 1.5) < .03,
+                    "an earlier queued seek cannot acknowledge the final seek");
+            until(player.get(), [](auto s) {
+                return !s.seek_pending && s.status == PLAYER_PAUSED && std::abs(s.position - 1.5) < .03;
+            });
             require(player_play(player.get()), "resume accepted");
             until(player.get(), [](auto s) { return s.status == PLAYER_PLAYING && s.position > 1.7; });
             require(player_seek(player.get(), 3.2), "playing seek accepted");
-            until(player.get(), [](auto s) { return s.status == PLAYER_PLAYING && s.position >= 3.2; });
+            until(player.get(), [](auto s) { return !s.seek_pending && s.status == PLAYER_PLAYING && s.position >= 3.2; });
             auto ended = until(player.get(), [](auto s) { return s.status == PLAYER_ENDED; });
             require(ended.position >= 3.8, "EOF drains media before completion");
             require(player_play(player.get()), "replay accepted");
             until(player.get(), [](auto s) { return s.status == PLAYER_PLAYING && s.position > .1 && s.position < 1; });
             require(player_close(player.get()), "close accepted while playing");
             auto closed = until(player.get(), [](auto s) { return s.status == PLAYER_EMPTY; });
-            require(closed.position == 0 && !closed.has_audio && !closed.has_video, "close clears media state");
+            require(closed.position == 0 && !closed.has_audio && !closed.has_video && !closed.seek_pending,
+                    "close clears media state and pending seeks");
             std::printf("PASS %s: open/play/pause/seek/end/replay/close\n", fixture);
         }
         require(player_open(player.get(), (std::string(argv[1]) + "/hdr.mkv").c_str()), "HDR open accepted");

README.md

@@ -22,8 +22,8 @@ The layout follows [IINA's video-first window](https://iina.io/img/screenshot.pn
 
 Opening video fits the window to its display aspect ratio, including non-square pixels, and constrains subsequent window resizing. Fullscreen retains the normal letterboxed renderer; audio-only playback and close release the aspect constraint. Extreme ratios that cannot fit both the screen and usable controls keep a freely resizable letterboxed window.
 
-- **Space:** play/pause. **←/→:** seek five seconds. The timeline slider seeks on release.
-- **↑/↓:** adjust volume by five percent. **M:** mute/unmute, restoring the previous audible level.
+- **Space:** play/pause. **←/→:** seek five seconds. The timeline slider seeks on release and holds the requested position until the core finishes queued seeks; old playback snapshots cannot pull the thumb back.
+- **↑/↓:** adjust volume by five percent. **M:** mute/unmute, restoring the previous audible level. The volume thumb is opaque light gray, independent of the frosted panel behind it.
 - **Double-click video**, **F**, or **⌃⌘F:** toggle native fullscreen. **Esc:** leave fullscreen.
 - **Single-click video:** hide controls. Mouse movement reveals them; they fade after 2.5 seconds, including while paused. Hovering the titlebar/controller, dragging, seeking, an inactive window, errors, or VoiceOver keep them visible.
 - Click the right-hand time label to switch between total and remaining time. The titlebar pin keeps the window on top.
@@ -32,7 +32,7 @@ Only implemented actions have controls; there are no placeholder playlist, subti
 
 ## Where to change things
 
-- `Sources/Core/player.h`: the C interface and authoritative state snapshot. Playback commands enqueue work; poll state for completion. Volume set/get is synchronous and uses a lock-free target gain. Callers own the opaque handle and must stop using it before destruction.
+- `Sources/Core/player.h`: the C interface and authoritative state snapshot. Playback commands enqueue work; poll state for completion. `seek_pending` is set synchronously when a seek is accepted and clears when all queued seeks on that timeline finish. Volume set/get is synchronous and uses a lock-free target gain. Callers own the opaque handle and must stop using it before destruction.
 - `Sources/Core/player.cpp`: single demux/decode worker, bounded buffers, timestamps, audio-master synchronization, paused previews, decoder/resampler drain, seeking, errors, and shutdown. A seek stops output and flushes all old timeline state before resuming.
 - `Sources/Core/output.hpp` and `Sources/macOS/Output.mm`: native output contract, allocation-free/nonblocking Core Audio callback and bounded audio ring, latency-aware presentation clock, retained frame mailbox, and Metal YUV conversion. The view can outlive the player safely.
 - `Sources/App/PlayerApp.swift`: MainActor state polling, file panel/Finder/drop handling, video host, AppKit glass and native slider cells, floating controls, visibility, video-fitted sizing, and native window integration.
@@ -44,7 +44,7 @@ Only implemented actions have controls; there are no placeholder playlist, subti
 make check
 ```
 
-Generates short fixtures and exercises the real playback interface and native outputs: audio/video, video-only, audio-only, non-square-pixel display aspect, pause, paused/playing seek, completion, replay, close, HDR rejection, failed-open recovery, and destruction while playing. It initializes the actual Metal shaders and uses an offscreen native window. It requires a working audio device and graphical macOS session, and plays short sine-wave audio. It is a runtime smoke check, not a mocked clock/device test.
+Generates short fixtures and exercises the real playback interface and native outputs: audio/video, video-only, audio-only, non-square-pixel display aspect, pause, paused/playing and queued seek acknowledgement, completion, replay, close, HDR rejection, failed-open recovery, and destruction while playing. It initializes the actual Metal shaders and uses an offscreen native window. It requires a working audio device and graphical macOS session, and plays short sine-wave audio. It is a runtime smoke check, not a mocked clock/device test.
 
 `make check-audio` runs just the audio-quality check. A check-only hook captures actual Core Audio callback PCM into preallocated storage and compares every sample against FFmpeg's reference output for PCM/AAC, 44.1/48 kHz, and coarse container timestamps. It checks fractional gain, silent muted startup, smooth live volume changes, and unchanged playback completion. A separate gapped fixture verifies that real timestamp gaps remain silent. Release builds contain no capture hook.
 

Sources/App/PlayerApp.swift

@@ -28,6 +28,7 @@ final class PlayerModel: ObservableObject {
     private var windowActive = true
     private var lastAudibleVolume = 1.0
     private var needsVideoFit = false
+    private var seekPending = false
 
     private init() {
         let player = player_create()
@@ -100,6 +101,7 @@ final class PlayerModel: ObservableObject {
         needsVideoFit = true
         commandError = nil
         isSeeking = false
+        seekPending = false
         seekPosition = 0
         window?.representedURL = url
         window?.title = url.lastPathComponent
@@ -117,7 +119,9 @@ final class PlayerModel: ObservableObject {
         isSeeking = false
         guard let handle, canSeek else { return }
         let position = min(max(0, seekPosition), duration)
-        commandError = player_seek(handle, position) ? nil : "Could not queue the seek. Please try again."
+        let accepted = player_seek(handle, position)
+        if accepted { seekPending = true }
+        commandError = accepted ? nil : "Could not queue the seek. Please try again."
         revealControls()
     }
 
@@ -133,6 +137,7 @@ final class PlayerModel: ObservableObject {
         window?.aspectRatio = .zero
         commandError = nil
         isSeeking = false
+        seekPending = false
         window?.representedURL = nil
         window?.title = "Player"
         revealControls()
@@ -140,9 +145,13 @@ final class PlayerModel: ObservableObject {
 
     func seekRelative(_ seconds: Double) {
         guard canSeek, let handle else { return }
-        let target = min(max(0, state.position + seconds), duration)
-        commandError = player_seek(handle, target) ? nil : "Could not queue the seek. Please try again."
-        seekPosition = target
+        let target = min(max(0, (seekPending ? seekPosition : state.position) + seconds), duration)
+        let accepted = player_seek(handle, target)
+        if accepted {
+            seekPosition = target
+            seekPending = true
+        }
+        commandError = accepted ? nil : "Could not queue the seek. Please try again."
         revealControls()
     }
 
@@ -234,7 +243,7 @@ final class PlayerModel: ObservableObject {
 
     private var shouldHideControls: Bool {
         canTogglePlayback && state.has_video && fileName != nil &&
-            !isSeeking && !controlsHovered && !titleHovered && !controlsDragging &&
+            !isSeeking && !seekPending && !controlsHovered && !titleHovered && !controlsDragging &&
             windowActive && errorText == nil &&
             !NSWorkspace.shared.isVoiceOverEnabled
     }
@@ -265,14 +274,18 @@ final class PlayerModel: ObservableObject {
 
     private func poll() {
         guard let handle else { return }
-        let next = player_get_state(handle)
+        applyState(player_get_state(handle))
+    }
+
+    func applyState(_ next: PlayerState) {
         if let revision = pendingRevision {
             guard next.revision != revision, next.status != PLAYER_OPENING else { return }
             pendingRevision = nil
         }
         let statusChanged = state.status != next.status
         state = next
-        if !isSeeking {
+        if !next.seek_pending || next.status == PLAYER_ERROR { seekPending = false }
+        if !isSeeking && !seekPending {
             seekPosition = min(max(0, next.position.isFinite ? next.position : 0), duration)
         }
         fitVideoWindow()
@@ -379,7 +392,9 @@ private struct PlaybackSlider: NSViewRepresentable {
             let width: CGFloat = volume ? 16 : 3
             let height: CGFloat = volume ? 12 : 15
             let knob = NSRect(x: rect.midX - width / 2, y: rect.midY - height / 2, width: width, height: height)
-            NSColor.white.withAlphaComponent(isEnabled ? 0.65 : 0.25).setFill()
+            let color = volume ? NSColor(white: isEnabled ? 0.85 : 0.45, alpha: 1)
+                               : NSColor.white.withAlphaComponent(isEnabled ? 0.65 : 0.25)
+            color.setFill()
             NSBezierPath(roundedRect: knob, xRadius: volume ? 6 : 1, yRadius: volume ? 6 : 1).fill()
         }
     }

Sources/Core/player.cpp

@@ -137,6 +137,7 @@ struct Player {
             state.status = PLAYER_OPENING;
             state.revision = revision;
         }
+        if (commands.back().action == Action::Seek) state.seek_pending = true;
         wake.notify_one();
         return true;
     }
@@ -179,6 +180,10 @@ struct Player {
         state.duration = duration;
         state.has_audio = tracks[0].codec != nullptr;
         state.has_video = tracks[1].codec != nullptr;
+        // The worker publishes only outside seek execution; retain pending for later queued seeks.
+        state.seek_pending = std::any_of(commands.begin(), commands.end(), [this](const Command &command) {
+            return command.action == Action::Seek && command.epoch == activeEpoch;
+        });
         state.video_aspect_ratio = 0;
         if (const auto *video = tracks[1].codec; video && video->width > 0 && video->height > 0) {
             const auto aspect = av_guess_sample_aspect_ratio(format, format->streams[tracks[1].index], nullptr);

Sources/Core/player.h

@@ -17,6 +17,8 @@ typedef struct PlayerState {
     double duration;
     bool has_audio;
     bool has_video;
+    // True from accepted seek until all queued seeks on this timeline finish.
+    bool seek_pending;
     // Display width / height, including sample aspect ratio; zero without video.
     double video_aspect_ratio;
     uint64_t revision;