Pulls the preserve-snap forward to step 2: it is the half with no UI and nothing
proposing today, and it needs nothing from the plate side but a fold that can
land last.
Makes the rule exact, because the direction is easy to get backwards and the
draft was vague about it. Slot k reads the latest preserved frame in
(d(k-1), d(k)], else d(k). The closure at native 13 in a 12-from-30 output is
recovered by slot 6, whose default is 15, reading 13 — NOT by slot 5 reaching
forward from 12, which would show it 17ms before the mouth shut and break the
invariant cadence_test already asserts.
Records where it goes, which is the part that was understated as "about thirty
lines". The slot interval exists only at clip.cljs:261 and group identity exists
only at symbol.cljs:399, so the interval has to be threaded down: two internal
signatures, not a drop-in. The rule's seat is the `(js/Math.floor lf)` default
`base-channel-frame` hands `pose/source-frame`, which leaves an explicit hand cut
beating a snap, as manual precedence requires.
And records the shortcut not to take: snapping at clip.cljs:261 needs no
threading and is wrong, because one native frame per output frame means the whole
picture reads 13 instead of 15 — a 67ms stale head to fix the mouth, fighting the
trace selection's own opinion about which head frame to show.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Corrects this plan's central claim. It said one component used twice, because
the prototype's `suggestPlateFrames` and timing-handoff's performance poses
looked like the same function. They are not.
A plate selection has to be NON-UNIFORM — that is the entire reason it exists. A
head still for sixty frames and then whipping across in ten wants two drawings
and then eight, and no nudging of a uniform grid produces that distribution,
because the spacing itself is the answer. A tolerance belongs here: the artist is
buying drawings.
A performance selection is not choosing sparseness at all; the output rate or the
exposure setting already did. What is left is which native frame each decided
slot reads, so nudging the grid is the right size of answer and a tolerance would
be a knob with nothing to control.
And the harder reason, which settles it: a selection cannot put a frame on screen
that the output grid never samples. At 12fps out of 30 a closure at native 13
falls between output frames 5 and 6, so keeping 13 in a set makes it available
and never shows it — exactly what time.md says about an event between output
frames. Only moving what output frame 6 reads can show it.
So the performance half is a backward-only snap of the grid's own pick toward a
preserved frame, about thirty lines plus a prepare step, and its marks come from
cuts `flow/freeze` already stores: the mouth's aperture threshold and the eyes'
`resolve-blink` with its hysteresis. No aperture signal, no new dense track, no
threshold decided twice. The nesting survives unchanged, because a kept plate
frame is just another mark in the same pile.
Records why the aperture signal is impossible as drafted — positions 5 and 15 of
LIPS-INNER survive `freeze/rings->flat` only at verts divisible by four — and
names commit 02069e8 as the one holding the now-uncalled extrema detection, with
the two conditions under which it would be wanted again.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
