fix: treat recordings without audio as a non-error transcription state

[EtienneLescot]

Observed

A screen-only recording with no system audio and no microphone is recorded successfully, but opening transcription reports NoAudioTrackError as a transcription failure.

Reproduction

1. Disable system audio and microphone.
2. Record a screen capture and open it in the editor.
3. Open the Transcription inspector.

Expected

The editor should clearly say that the recording has no decodable audio / cannot be transcribed, without presenting it as a failed transcription job. A non-error empty state would make the distinction clear.

Environment

• Windows
• OpenScreen 1.11.0-rc.1, CI artifact from Actions run 34114348128
• Manual computer-use E2E pass

The recording itself, cursor sidecar, editing flow and export all succeed; this is an error-state UX issue.

[CyberSparkx]

Fix submitted — PR #637

This issue is fixed in #637.

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Root cause

classifyTranscriptionError() in src/lib/ai-edition/transcription/status.ts only matched the old renderer-side error strings ("no audio track", "zero audio frames"). When the native Windows WGC capture helper throws, the IPC layer serialises it like this:

Error invoking remote method 'stt:transcribe': NoAudioTrackError: No decodable audio in C:\rec.mp4: Output file #0 does not contain any stream

Neither error.name === "NoAudioTrackError" nor the "No decodable audio" substring was being tested, so the error fell through to the generic "error" bucket — displayed in red as a failed transcription job, complete with an error toast.

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What changed

File	Change
src/lib/ai-edition/transcription/status.ts	classifyTranscriptionError() now checks error.name, /noaudiotrackerror/i in the message, and /no decodable audio/i — all mapping to kind: "no-audio" (permanent, non-retryable, not an error)
src/components/ai-edition/TranscriptionStatus.tsx	TranscriptionStatusDot uses amber (not red) for no-audio / unsupported-audio; tooltip shows the human label only, not the raw ffmpeg string
src/components/ai-edition/v4/MediaStage.tsx	Status pill uses amber (--warn) for silence; body area shows friendly noAudioTrackHint copy instead of the error hint

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Effect

	Before	After
Transcription inspector pill	🔴 Red "Transcription failed"	🟡 Amber "No audio track"
Status dot on media card	🔴 Red error dot	🟡 Amber informational dot
Error toast	❌ Shown for every silent recording	✅ Suppressed — silence is not a failure
Tooltip raw message	❌ Raw ffmpeg output shown	✅ Human label only
Persisted on asset (no-retry)	✅ Already persisted	✅ Still persisted, now as "no-audio"

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Tests added (78 tests, all passing)

• classifyTranscriptionError → native NoAudioTrackError and IPC-wrapped variant both yield "no-audio" + isPermanentFailure === true
• transcriptionStore → NoAudioTrackError persisted as "no-audio" on the asset; no error toast fired
• TranscriptionStatusDot → amber dot + clean title for silence; red dot + engine-message title for real errors

[github-actions]

Fixed by #638 and merged into main.

This change is assigned to the Next Release release milestone and is not necessarily available in the latest downloadable desktop release yet. It is currently marked as status: pending release until a packaged release containing it is published.