forked from unom/punktfunk
enricobuehlerandClaude Fable 5
0e60e58cab
Task 1 (latency): the transactional present now commits from the RENDER
thread inside an explicit CATransaction + flush() instead of hopping to
main. The present harness (2026-07-21, 240 Hz Studio, full-size window)
measured the main hop batching presents at runloop-iteration rate when
main is busy — an active implicit transaction NESTS the explicit one —
which is the field's presents=55 @ fps=240 / display_p50 18.6 ms.
Off-main commits measured immune to main churn: glass p50 ~10 ms,
cadence a clean 4.17 ms at 240. flush() is load-bearing: without it the
render thread's own implicit transaction (drawableSize/colour writes)
swallows the explicit commit and NOTHING reaches glass — the harness
reproduced the exact freeze (every present dropped). Legacy main-hop
kept as PUNKTFUNK_TXN_PRESENT=main for field A/B. New pf-windowed
Console line (subsystem io.unom.punktfunk, category presenter)
decomposes the issue side per second.
Task 1 lever D: the f407f418 IOSurface contents-swap path is
resurrected format-aware as WindowedPresentMode.surface — bgra8 SDR /
rgba16Float+PQ-tagged HDR pool, swap committed off-main from the
completion handler; EDR anchored by the metal layer underneath.
Env-only prototype (PUNKTFUNK_WINDOWED_PRESENT=surface) until the HDR
composite is eyeballed on glass.
Task 2 (setting): punktfunk.windowedSafePresent (default ON =
transactional mitigation; OFF = the fast async path whose panic the
saga is about — the caption says so in plain words). Rows in the touch
Settings (Presentation) and gamepad settings, macOS-only.
PUNKTFUNK_WINDOWED_PRESENT=async|transaction|surface overrides for dev
A/B. maximumDrawableCount stays 3 — the harness measured 2 starving the
render loop (172/s) and worsening glass p50.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>