[miguel-heygen]

What

check no longer reports dead_stretch ("Nothing on screen changes for N s") while an SVG stroke draws on. The motion audit's "nothing moves" reads the same signature, so it stops saying it too.

Why

A whiteboard film drew its lines with the usual stroke draw-on (stroke-dasharray with a tweened stroke-dashoffset). The rendered frames showed each line drawing, but the craft pass reported the stretches as dead.

The liveness signature (motion-signature.browser.js) reads each element's box, opacity and paint (color, textShadow, fill, stroke). A dash offset tween moves none of them: the path's box and colour stay the same while the visible part of the line grows. So two frames of a line half drawn and fully drawn signed the same.

Released 0.9.15 on a 12 s film whose only motion is one path drawing on over 10 s: dead_stretch "Nothing on screen changes for 9.00 s (0.00–9.00 s)".

How

strokeDashoffset and strokeDasharray join the content paint channel, beside fill and stroke. Both are computed style in Blink, so attribute, CSS and inline-style tweens all show up.

Test plan

• Unit tests added/updated:
  • fails without the fix: motion-signature.browser.chromium.test.ts "sees an SVG stroke drawing on, which moves no box and no color": in real Chromium, changing a path's stroke-dashoffset changes both the sweep and the liveness signatures. It fails with the two properties taken out.
  • motion-signature.browser.chromium.test.ts, motion-signature.browser.test.ts, motion-sample.browser.test.ts and craftAudit.test.ts (110) pass three runs in a row, with the Chromium suite running (not skipped).
• Manual testing performed: the CLI built from this branch, check --json on the 12 s draw-on film above: ok: true, no craft or motion findings. Released 0.9.15 on the same film reports the 9 s dead_stretch.
• Documentation updated (if applicable): none needed.
• Comments follow CONTRIBUTING.md "Comments": no new comments.

Size

Two lines of source in one file and one test. One fix: the liveness signature sees a dash offset.

[heygengenesis]

Verdict: APPROVE · 0 blockers · 0 important · 0 nits · head 6ec1e38f

The fails without the fix: test holds. In real Chromium, with the two properties removed it fails with an identical sweep signature; with them in, all 48 Chromium tests in the file pass. All workflows on this head are green.

Scope

Read both files. paintChannel hashes raw computed values, and color already made every element's content-paint hash non-empty. So adding two inherited properties only changes the hash when a dash value actually changes; a still dasharray stays still. No prior reviews.