WP4 + WP5 of design/desktop-presentation-rebuild.md, on top of the WP1/WP2
engine. The engine shipped with no way to choose it and no way to see what it
cost; this closes both.
WP4 — the display stage splits into `pace` (decoded → present-submit, our own
pipeline) + `latch` (submit → on-glass, the presentation queue and the vblank
wait), off the `submitted_ns` stamp WP2 already carried. That split is what
makes a high `display` self-diagnosing: latch dominating is the vsync floor or
a standing queue, pace dominating is us. A `present:` line joins the Detailed
tier naming the live swapchain mode — the answer to most "why is my latch a
whole refresh" questions, since a MAILBOX request silently lands on FIFO
wherever the driver has no mailbox — plus the engine's counters, rendered only
when they are non-zero so a healthy latency session shows just the mode.
Deviation from the plan: the planned `display_adj` twin is NOT here. It was
specified as `display − latch_p50` for parity with the Apple HUD's shaved
figure, but with a real per-sample `pace` percentile that twin is the same
quantity derived worse (subtracting percentiles). `pace` IS the
Apple-comparable number — Apple subtracts its OS present floor, the latch is
ours — and the user docs now say exactly that.
WP5 — Prioritize + Smoothness buffer on all three surfaces: the GTK dialog (a
new Presentation group on the Display page), the WinUI settings page, and the
console settings screen, which is the ONLY editor reachable in Gaming Mode and
so the one that decides whether Deck users can reach this at all. The buffer
control follows the intent the way echo cancellation follows the mic: hidden on
the desktop shells, dimmed and inert on the console, where a row that vanished
mid-list would shift everything under the cursor.
The V-Sync and VRR rows are deliberately NOT here. Their settings exist and are
profile-routed, but the swapchain does not honour them until WP3, and a toggle
that does nothing is exactly how "Full chroma (4:4:4)" shipped inert on desktop
for three releases after being announced.
Buffer labels carry no millisecond hints (Apple/Android derive them from the
session refresh): under a Native mode the shells do not know the refresh at
settings time, so the captions state the cost as one refresh per frame rather
than a confident wrong number.
Docs: the stats page documents the split and the `present:` line, and stops
claiming Linux/Windows measure to the present instant (untrue since
present_wait); client-settings documents both new rows and drops the stale
claim that the desktop 4:4:4 toggle has no effect (it was wired to
VIDEO_CAP_444); configuration documents PUNKTFUNK_PRESENTER and
PUNKTFUNK_PRESENT_DEBUG.
Gates: punktfunk-rust-ci linux/amd64 — fmt, clippy -D warnings over
pf-client-core, pf-presenter, pf-console-ui, the session binary and the GTK
client, 158 tests. The WinUI leg cannot be reached by any Linux or macOS check,
so it was compiled on the Windows runner .133: clippy -D warnings and tests
both exit 0, against a tree proven by content to contain the edit. ⚠ The first
run there reported a false pass — the script printed its done-marker while the
log carried a test failure (a STATUS_DLL_NOT_FOUND launch failure, ffmpeg's
DLLs missing from PATH); the harness now echoes each phase's exit code so the
verdict is a fact in the log rather than an inference from a marker.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Opus 5
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