fix: studio save, memory and storage issues in multitrack recording

[Nowkoo]

Fixes bugs and performance problems found while reviewing the multitrack studio released in v3.3.0, focused on server-thread stalls, memory use and disk growth. One commit per topic.

Correctness

• Stopping a take no longer blocks the server thread. The final take is written by the shared FIFO writer after any older checkpoint; it stays in memory while saving, and edits are refused until the write completes. A failed write keeps the take for retry.
• Keeping a take uses the track's current volume and mute, not the mix captured when recording started.
• Stop cancels private samples (previews, backing tracks, metronome) already sent to the client. They now use the Players category and are stopped per sound; live instruments and jukeboxes keep Records and are not cut.
• Studio files share a 32 MB read/write limit, checked before replacing the previous file, so a saved project can always be read back.

Memory and server-thread time
Measured with 36 projects of 7,500 notes (TF Main limits):

• Decoded notes share one copy of each instrument and sample name: a project goes from about 1.11 MB to 0.22 MB of heap.
• The library, /music projects, the 36-project limit and deletion read a per-owner library.index of project summaries instead of decoding every project. Listing goes from about 1.9 s and 40 MB to under 5 ms. The index is keyed by file size and modification time and rebuilds itself when missing, stale or damaged. The first listing after upgrading builds it once.
• Saves no longer reparse the selected file each time (also on every checkpoint), and serialize the project once for both copies.
• Disconnect and shutdown write only unsaved takes instead of every cached project, and a disconnect evicts the cached project. "Take saved" is sent only for finished takes.
• Jukebox playback reads the record once a second instead of copying the block state every tick. Ejecting or breaking still stops it immediately.
• The jukebox click handler checks the block type before getState(), and ItemsAdder station lookups cache their reflective methods.

Disk

• Edition IDs are derived from their content, so republishing unchanged music reuses the earlier edition instead of adding a file.
• New publish-cooldown-seconds in studio.yml (default 30, 0 disables).
• Startup removes studio-*.tmp files left by an interrupted write.

Behaviour changes

• The delete confirmation compares a project summary (title, track count, length, pending take). Mix-only changes no longer block a confirmed deletion.
• Identical republications share an edition ID.

Validation

• Java 21 mvn clean verify: 298 tests passed; 100% instruction and branch coverage, with no production exclusions.
• Still to check on TF Dev with a real client: the audio behaviour of Stop and the Players slider.

🤖 Generated with Claude Code

[coderabbitai]

Important

• 🔍 Trigger review

This repository does not receive automatic reviews because it has fewer than 10 stars.

⚙️ Run configuration

• Configuration used: Organization UI
• Review profile: CHILL
• Plan: Advanced
• Run ID: b9970592-6757-4eb5-880f-69178bb787c1

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