[miguel-heygen]

What

The late-start measurement in extractMediaMetadata carries its meaning in names (startsLate, lastPacket) instead of four comment lines. No behaviour change.

Why

The change that measures late-starting videos to their last packet raised packages/engine/src/utils/ffprobe.ts's comment share from 13.5% to 13.7%, which the comment ratchet refuses. It merged with that check red; this brings the file back under its share.

Related work

Refs #6736.

How

Drops the doc line on resolvePlayableVideoDuration and the three-line comment above the late-start read. The reasoning (ffprobe's durations do not all run from the first frame in Matroska and fragmented MP4; a failed read keeps ffprobe's duration) is in #6736's description.

Test plan

• comment-ratchet.mjs against the merge base: clean.
• streamStartOffset.test.ts: 24 of 24, 3 runs in a row; engine frame extractor and ffprobe suites: 410 passed, 1 skipped.

[github-actions]

Edit accuracy: accurate 271 (base branch 271), smooth 110 of those

The gate passes.
Smoothness is reported in the artifact, not gated. A case fails only if it fails 2 of 3 runs.

Quarantined, measured but not gated (0)

Unstable (3)

• seqplainkeys-none-center-r0-root-z100: tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo false, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true
• seqplainkeys-none-px-r0-root-z100: tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo false, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true
• seqplainkeys-none-pct-r0-root-z100: tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo false, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true / tracking 0.06, pressJump 0, drop 0, reload 0, render 0.03, renderKey -, undo true, teleport true

[heygengenesis]

Verdict: APPROVE · 0 blocker · 0 important · 0 nits · 6b7fad08

The behaviour is the same: startsLate and lastPacket take the place of the inline condition and last, and only comments are removed. Comments (the ratchet) and CI pass.

Required Tests on windows-latest is red, but this PR didn't cause it. streamStartOffset.test.ts:389 (fragment-cut.mp4 3.54 vs 3.375, late.webm 4.04 vs 3.52) fails the same way on main at the merge base 22b53c0 (#6736, run 40873362926). The other failure, autoUpdate.test.ts in cli, passes on main and is unrelated, so it looks like a flake. This PR can't merge until main's Windows late-start measurement is fixed or an admin merges it.