Stop-and-drop, the popover EJECT button, and the cassette drag-out now all produce the same shareable MP3 (cover art embedded), instead of two diverging artifacts (MP3 vs raw 4-channel WAV). - exportTapeMP3(): ejects + transcodes once, cached per take, WAV fallback - pre-warm on the recording→idle edge so the first drag/eject is instant - tapeExportLock serializes the encode (no duplicate ffmpeg on same temp); all main-thread/NSWorkspace work kept outside the lock (deadlock-free) Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>