- music-renderer: saveMidiFile export (JSON, no LilyPond), getRenderFile prefers original.midi, fix self-copy bug
- server-v2: POST /api/music/midi now saves to workspace/music/<name>/ and returns JSON immediately; new SSE endpoint /api/music/midi-score for on-demand LilyPond
- index.html: buildMidiPickerWidget with color-coded buttons (green/purple/amber), MIDI download moved inside player tab, score panel default closed
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>