Step core animation by the shell's clock and sleep to the next wake

A shell now answers Host.now, its monotonic clock in ns, and the pump
advances core animation to it: one .tick per whole 16 ms frame since core
time last stood still. The same animation therefore takes the same time at
60, 120 and 144 Hz, over ssh and after a slow frame (the GUI's re-armed
clock ran them ~25% slow at 144 Hz; the tty's post-frame sleep drifted).
nextWake() lists every core animation in one place: a frame from now while
anything moves, the end of the wait while something only waits (a message
lingering, the look-hover delay), null when idle. Shells sleep exactly that
long, and a wait is jumped to its end in one step, so an 800 ms linger
costs one frame instead of fifty. An overshoot under 1.5 ms after a step is
let go: at 60 and 120 Hz every display frame takes exactly one step (a 16 ms
frame against a 16.67 ms vsync would otherwise double-step every 24th).

The six tick drivers are gone: tty's timer thread only times the wait,
interruptibly (a newer, shorter request cuts short a sleep still timing a
longer one); the GUI's
AnimationClock, web's JS tick bank (pardes_tick now takes rAF's timestamp),
the detached server's and the board's ticks; grid mode steps a virtual
clock straight to each wake. PARDES_TEST_CLOCK, set by the snapshot
harness, gives tty and the detached server the same virtual clock.

Every stepped frame is drawn. The old pump never drew the last frame of a
fade (a .tick asks for no frame, and the fade was over by the check), so a
theme switch stopped at 9/10 of the way until the next input: theme.golden,
themesel.golden and the GUI's acme-light scene move to the theme's true
colours, and nothing else changes. The frozen previous grid is captured only
while a panel transition is chosen, not on every idle frame.

1 files changed, 1 insertions, 1 deletions

diff --git a/docs/render-pipeline.md b/docs/render-pipeline.md
index 2a679b8d..590a7e72 100644
--- a/docs/render-pipeline.md
+++ b/docs/render-pipeline.md
@@ -803,7 +803,7 @@ stripped. No visual change until stage 9 unless stated.
 |---|---|---|
 | 0 | GUI capture goldens: a handful of scenes rendered hidden in capture mode, PPM hashes checked in (same machine/driver) | the safety net the GUI stages need; machine- and driver-specific, so a LOCAL gate only, never CI |
 | 1 | pure moves: render → `src/draw.zig`; Presentation/animation out of layout.zig | no behaviour |
-| 2a | clock plumbing: `now_ns` into pump/events, `nextWake`, `advance`, deadlines for linger/hover; all shells pass now and sleep to the wake; six tick drivers deleted; ack moves into pump; capturePrevious only when transitions are on. Animations still compute `frame = floor(elapsed / 16 ms)`, so every curve is identical | pacing is corrected (144 Hz no longer ~25% slow, ssh no longer drifts): a bug fix allowed in this phase. Unit tests step an injected clock by exactly 16 ms, so their numbers do not change. The snapshot harness runs the binary with `--test-clock` (each core-time step is exactly 16.67 ms per tick request, as today), so goldens see the same sequence and `stable` (test/snapshot.zig ~861) is unaffected by wall-time pacing |
+| 2a | clock plumbing: `Host.now` (the shell's monotonic ns) and `Pardes.advance(now)`, which runs one `.tick` per whole 16 ms frame since core time last stood still; `nextWake()` lists every core animation and answers the next frame while anything moves, the wait's end while something only waits (message linger, look-hover delay), null when idle; the pump sleeps to it and draws only stepped frames. No shell posts `.tick` any more (tty's timer thread only wakes the wait; GUI's AnimationClock, web's JS tick bank and the detached server's and the board's ticks are gone; grid mode moves its virtual clock straight to the next wake). `acknowledgePanelPresentation` stays in the shells (revisit at stage 8: grid mode acks `&.{}` on purpose). capturePrevious only when transitions are on. `.tick` stays as the one-frame step `advance` and the unit tests use, so every curve and every asserted number is unchanged | pacing is corrected (144 Hz no longer ~25% slow, ssh no longer drifts): a bug fix allowed in this phase. PARDES_TEST_CLOCK (set by the snapshot harness): tty and the detached server answer a virtual clock that a timed-out wait moves exactly to the core's next wake, so goldens replay the same frame sequence on any machine load. Review fixes: tty's wake timer is interruptible (a newer, shorter request cuts short an older sleep); a wait (linger, hover delay) is jumped to its end in one step, never counted against the 240-frame catch-up cap; an overshoot under 1.5 ms after a step is let go, so 60 and 120 Hz take exactly one step per display frame. Known exceptions: the GUI still polls every 16 ms when idle (SDL events, gamepad, fs tick, smooth scroll depend on it; revisit at stage 8); a minimized GUI renders every stepped frame of a running animation (stage 8) |
 | 2b | (on `fx`, feel-reviewed) Tween/Spring curves, settle rules, OKLab crossfades, new durations from §8.1 | a look change, kept apart from 2a so either can be bisected |
 | 3 | paint functions take `s: *Surface`; delete the swap hack | mechanical, wide |
 | 4 | PLACE: Region list built once; renderPane/tags/notices read their rects from it | wait for tag→Text; the refactor is already replacing BOX_H with `pane.tag_rows` and `p.tagTop/bodyTop(pane, r)` — PLACE absorbs those into the region rects |