Complete spec for fixing the playout ring buffer cursor race that
causes 12-16s bidirectional silence mid-call. Includes exact code,
memory ordering rationale, unit tests, and verification steps.
Any agent can implement from this document alone.
See also: debug/INCIDENT-2026-04-06-playout-ring-desync.md
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
