forked from unom/punktfunk
enricobuehlerandClaude Opus 5
5f55fa874a
WP1+WP2 of design/desktop-presentation-rebuild.md. The shared Linux/Windows session client presented arrival-paced with no pacing layer at all: two depth-2 newest-wins hops into a drain-to-newest and an immediate present. That IS the lowest-latency intent, but it was unnamed, unselectable, and had no alternative — and on a surface without MAILBOX (AMD's Windows driver offers none, and any compositor holding images does the same) the swapchain's own FIFO becomes a standing queue worth a measured 11-13 ms at 60 Hz. WP1 — the settings cluster, under the keys the Apple client already writes into the shared profile catalog (present_priority / smooth_buffer / vsync / allow_vrr): mismatched names would ride SettingsOverlay::extra, carried but never applied. PresentPriority::resolve mirrors the Android reference exactly (anything but an explicit "smooth" is latency; a buffer outside 1..=3 becomes 2), so a profile authored on any client means the same thing on all of them. Only the first two are consumed here; vsync/allow_vrr land in WP3. WP2 — the engine (present_pace.rs, pure state + arithmetic, 6 tests): - FrameStore: newest-wins slot, or the smoothing FIFO with preroll-to-capacity, drop-oldest overflow, and an underflow that re-arms the preroll (repeat by omission) — the Apple/Android semantics, with qDrop/qDry counters. - LatchClock: the panel grid learned from VK_KHR_present_wait glass stamps, min positive spacing capped by the mode refresh (measured, never queried — VRR and Android's per-uid refresh lie both punish trusting a reported rate). It now also publishes the host-facing LatchGrid, so the phase-lock report and the local scheduler cannot disagree about the grid. - PresentGate: one undisplayed present in flight on FIFO surfaces, with the 100 ms stale force-open. This is the standing-queue killer, and it is inert on MAILBOX/IMMEDIATE and without present timing — where behaviour stays byte-for-byte the shipped arrival pacing. Wiring: glass samples drain every pass (a 1 Hz batch would starve clock and gate) and the waiter pushes an SDL wake, so a gate reopen never waits out the event timeout; smoothness serves one frame per latch slot and tightens the loop's wait to that deadline; the adaptive slot margin starts at 0 and widens +500 us per missed window toward 2.5 ms (a fixed lead was measured to be pure display tax). PUNKTFUNK_PRESENTER=arrival disables the whole engine for field A/B without a rebuild. PyroWave collapses smoothness to latency for the stream: its plane-ring retirement accounting assumes the depth-2 newest-wins hand-off, and all-intra frames make buffering moot anyway. Gates (punktfunk-rust-ci, linux/amd64, sources touched first so a warm target cannot print a vacuous Finished): clippy -D warnings across pf-client-core, pf-presenter and punktfunk-client-session; 80 + 32 tests pass; rustfmt clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>