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**The pin.** Pin a TAG, never a bare sha. A sha reachable only from an auto/* branch is orphaned when that branch is deleted or -- worse -- squash-merged, because squash creates new commits: main looks like it contains the work while the pin becomes unreachable and this project stops building for a fresh checkout, silently, at their build. formats-pin-2026-08-29 exists for the current state. Also says plainly why NOT to float to a branch, which was the tempting fix: Cargo resolves a git dependency once and writes the sha into Cargo.lock, so floating gives staleness you cannot see instead of staleness you can read. push-work now pushes --follow-tags so annotated tags travel with the branch. **Audio.** docs/AUDIO-VERIFICATION.md separates three questions that were being asked as one: is the transcode faithful (no engine, no device -- a file-vs-file difference measurement), does Godot route it (AudioEffectRecord on the Master bus writes a WAV from a headless run), and what does the GAME play (a PulseAudio null sink, which needs a rebuild). It leads with the three ways the fidelity measurement lies, because all three were hit on the first attempt and each produces a confident wrong number rather than an error: unaligned subtraction, mismatched channel layouts, and probing a file another process is still writing. The 5.1 disc fact deliberately is NOT copied here -- it lives in the RE corpus at docs/re/structures/movie-audio-channels.md and is linked, so there is one copy to keep true rather than two that drift. Same reason HANDOFF is a summary with links. The downmix itself stays flagged as an unmade decision, not quietly resolved. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>