Three findings of the v1.70.0-beta.1 audit, all on the transition path
added by #82, all of the same shape — the new path did not inherit a
property the old one had.
B1: persisting the zoom moved into _settleCameraTransition only, and a
cancellation never settles. Touching the plan mid-flight — the literal
scenario of the issue — froze the shown frame and threw it away; before
which kind it is: the user one (_stagePointerDown) persists the frame
that stays on screen, the eleven structural ones keep writing nothing.
The distinction is now also written down in spec #82 §13, which had one
line for both.
B2: the anchor was read from the presented (lagging) frame while the
zoom accumulated from the target, so a six-notch trackpad series walked
the point under the cursor 17 px away — against §10's own promise. Both
now come from the same state. Spec §10 said to use the presented frame
and to keep the anchor within 0.5 px; those two are incompatible, and
the paragraph is corrected rather than left as a trap.
M2: the feather freeze keyed on the two gesture flags, which an
animated transition does not set, so every tween frame rebuilt the blur
region. It keys on 'the camera is still' now.
Guards: unit tests pin the anchor at 1e-9 across 8/16/33 ms series and
prove zoom accumulation is untouched; the smoke checks the shown zoom is
the stored one, that a structural cancellation stores nothing, and that
the anchor holds; three mutants (cancel-loses-zoom, anchor-from-
presented, feather-thaws) were run by hand and each reddens.
User-Visible: yes
Issue: #396
Codex