Carries forward from iter5 close: cap_pool race fix (sonnet C4),
msync verify (sonnet C3), upstream prep (gated), perf cell, MPEG-2
audit, V4L2_MEMORY_DMABUF.
NEW from iter5 stock-Brave investigation: candidate C — verify
chromium-fourier + iter5 driver compatibility. Stock Brave doesn't
even reach VAAPI (GL bindings die before decoder selection); the
chromium-fourier campaign is still required for the GL-stack fix.
Open question: which of chromium-fourier's libva-side patches are
obsoleted by iter4+iter5 fixes.
Recommended primary: A+B (cap_pool race fix + msync verify) —
both are iter5 sonnet caveats, small scope, prereqs for upstream.
Or A+B+D if iter6 becomes the upstream-prep iteration.
Phase 1 lock awaits user pick.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
