docs(media): correct the audio claim — a video file's sound is silent, not loopback-carried

Controls/LeftPanel.xaml

@@ -746,7 +746,7 @@
                                 <CheckBox Style="{StaticResource PropertyPillCheck}" Margin="10,4,0,4"
                                           Content="Loop" IsChecked="{Binding SelectedElement.MediaIsLooping, Mode=TwoWay}"
                                           ToolTip="Restart from the beginning at the end of the file — for starting-soon and BRB loops"/>
-                                <TextBlock Text="Audio plays through your desktop audio, like TRAX."
+                                <TextBlock Text="Picture only — a video's own sound is not played yet."
                                            Style="{StaticResource PropertyHint}"/>
                             </StackPanel>
 

HANDOFF.md

@@ -7,7 +7,9 @@
   2026-11-04.
 - New test `MediaSourceAcquisitionTests` (add → one decoder starts + frames reach the layer + loop flip
   reaches the decoder + remove → stops). App build is 0 warnings.
-- Volume is deliberately unwired: media audio rides the desktop loopback, so a slider would do nothing.
+- **Media is picture-only:** `MediaVideoSource` decodes with `-an`, so a video file's own soundtrack
+  is silent on stream — the loopback does not carry it because nothing plays it. Two routes recorded
+  in `task-21` item 10 (alert-style mixer feed vs TRAX-style local play); no volume slider until one exists.
 
 ## Next action
 

TASKS/task-21-media-source.md

@@ -7,7 +7,8 @@
 
 ### Status: ✅ Complete 2026-11-05 — a video file added in the (+) menu decodes, composites into the
 preview and the stream, loops on the creator's toggle, and stops when the layer or its last scene
-reference goes away. Audio is the desktop loopback (TRAX-style); a per-file volume route is not built.
+reference goes away. **Picture only: the file's own audio is not played anywhere** (the decode pipe
+passes `-an`), so a video with a soundtrack is silent on stream — the audio route is open, item 10.
 
 1. ✅ `MediaSourceType` enum: `Video`, `Audio` (audio-only files via media source)
 2. ✅ `SourceType.MediaSource` addition to the enum
@@ -24,9 +25,13 @@ reference goes away. Audio is the desktop loopback (TRAX-style); a per-file volu
    when `Looping` (fresh process per pass). `MediaIsLooping` reaches the session through the manager's
    per-path `loopProvider` at start and `SetLooping` on a live toggle. Rule (recorded): the path's
    session loops if **any** live media reference has it on, because one decoder is shared per path.
-10. ⏸ Volume control — deliberately not wired: media audio is captured by the desktop loopback like
+10. ⏸ File audio + volume — **the file's soundtrack is silent everywhere today**: the decode pipe
-    TRAX, so a per-file slider would be a control with no audible effect. Revisit only with a local
+    passes `-an`, so nothing plays it and the desktop loopback has nothing to carry. Two established
-    audio route for the file's own stream.
+    routes when this is taken: **alert-style** (a second `f32le` pipe into the mixer —
+    `AlertClipDecoder.RunAudioAsync` is the working model, independent of desktop capture) or
+    **TRAX-style** (`MusicPlayer` plays it to the default device, so the loopback, the desktop fader
+    and ducking all apply — at the cost of a second clock to hold in sync with the video). Product
+    call; not started, and no volume slider until one of them exists.
 11. ✅ UI: `AddMediaCommand` (+ menu → "Video File", video-filtered `OpenFileDialog`), `ChangeMediaFileCommand`
     ("Change…" in the properties panel), loop toggle, video name display.
 12. ✅ Schema migration for media source settings (file path, loop, volume) — shipped with item 3.
@@ -36,7 +41,10 @@ reference goes away. Audio is the desktop loopback (TRAX-style); a per-file volu
 ### Design decisions
 
 - **FFmpeg handles all formats** — no codec-specific code. FFmpeg already in the project.
-- **Audio plays through the desktop channel** — media source audio is captured by the WASAPI loopback (like TRAX/game audio). No separate audio routing needed.
+- **Audio is NOT wired, and it is not hiding behind the loopback** — `MediaVideoSource` decodes with
+  `-an`, so a video file's soundtrack is silent on stream today (the loopback only carries what the
+  machine actually plays). Item 10 records the two established routes; do not describe media as
+  audible until one is built.
 - **This pairs with TRAX** — TRAX is background music, media source is background video. Together they make non-Live scenes (Starting/BRB/Ending) feel polished.
 - **Not a full NLE** — no trimming, no multi-track, no effects. Just "play this video in the scene."
 - **Layers are defined in Live first** (creator 2026-11-05): this unit adds the layer and the picker in

docs/ai/frame-pipeline.md

@@ -799,8 +799,9 @@ Full suite 290/291 passing, the sole failure the pre-existing compositor pixel t
   released (`GetActiveKeys`). Loop is a manager-level per-path answer: the ctor takes
   `Func<string,bool>? loopProvider` (production: "any live media reference loops"), applied before
   `StartAsync`, and `SetLooping(key, bool)` applies a live toggle. A file swap releases the old path after
-  the layer no longer references it. Volume stays unwired on purpose — sound rides the desktop loopback
+  the layer no longer references it. **A video file's own soundtrack is silent today** — the decode pipe
-  (TRAX-style), so a per-file slider would be a control with no effect.
+  is `-an`, so nothing plays it and the loopback has nothing to carry; wiring it (alert-style mixer feed
+  or TRAX-style local playback) is open, and no volume slider exists until then.
 - **Social bar on the output (bar bug-fix branch):** the `FramePump` takes an optional
   `socialBar: Func<(VideoFrame? Frame, SocialBarPosition Position)>?` seam, re-read **every frame** (so a
   mid-stream position flip applies immediately). The strip is pre-rasterized by `Compositor/SocialBarRenderer.cs`

docs/ai/overlays.md

@@ -99,8 +99,9 @@ published decisions (recorded in `TASKS/task-43-native-alerts.md`):
   `RawVideoFrameReader` feed loop, same `IFrameRateProbe` + delay pacing, both behind
   `IDecodeProcess`. What differs is ownership and role, not decoding: alerts are per-play
   and disposed at drain, media is a refcounted per-path session; alerts also run an
-  `f32le` audio pipe into the mixer, media deliberately sends no audio (the desktop
+  `f32le` audio pipe into the mixer, media runs none at all (`-an`) — so a media file's
-  loopback carries it, TRAX-style); alerts play once, media loops. A shared raw-video pump
+  soundtrack is silent today, and task-21 item 10 holds the two routes for changing that;
+  alerts play once, media loops. A shared raw-video pump
   is the obvious consolidation if a third consumer appears — do not do it for two.
   Fades in/out via **`FadeDurationSeconds = 0.30`**
   (`AlertOverlayLayer` const): fade-in by `elapsed` on straight-alpha frame copies;