The windowed-macOS "mismatched swapID's" @UnifiedPipeline.cpp kernel
panic is the CAMetalLayer ASYNC image queue (commandBuffer.present,
mandatory with displaySyncEnabled=false) diverging from WindowServer's
compositor on a high-refresh composited session — it survived glass
pacing (PyroWave, 2026-07-18) and hit windowed HEVC on the same 240 Hz
Mac Studio (2026-07-21), so it's the async queue itself, at any codec
or pacing.
f407f418's mitigation routed windowed PyroWave through a BGRA8 IOSurface
layer.contents pool, which cannot carry HDR — extending it to HEVC would
have tone-mapped windowed HDR down to SDR. Instead, present the drawable
through a Core Animation transaction (CAMetalLayer.presentsWithTransaction)
for every windowed session: commit, waitUntilScheduled, then drawable.present()
inside a CATransaction, so the swap commits with the layer tree and stays
in lockstep with the compositor instead of racing it. The full
rgba16Float / PQ / EDR render path is untouched — windowed HDR is real
HDR again. Fullscreen keeps the async path (direct scanout, lowest latency,
no panic there).
Removes the IOSurface surface pool, its surfaceLayer sibling, and the
macOS windowed PQ->SDR tone-map (tvOS keeps its no-headroom tone-map).
Net -150 lines. swift build + 169 tests green. Needs on-glass soak on
the 240 Hz Mac Studio (kernel race — only real hardware confirms).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
f49d38826b