[miguel-heygen]

What

A studio test Chrome that hangs after it starts listening is killed at the 20 s launch limit and launched once more, instead of holding the test until its 60 s timeout.

Also carries a doc-comment correction on createSessionInitBudget (from #7333): each setup step is bounded by the budget on its own, not setup as a whole. No code change there.

Why

On a Windows runner, chromeTestUtils.browser.test.ts timed out at 60 s. Its log shows Chrome printing DevTools listening on ws://... 2.5 s after launch, then nothing: puppeteer.launch never returned, and the launcher never logged a failure or a retry.

Puppeteer's timeout only bounds the wait for that DevTools line. The CDP setup that follows (CdpBrowser._create) is bounded by protocolTimeout, 180 s by default, so the launcher's 20 s retry never fired for a hang in that window.

Related work

Supersedes #7333 (its one comment change is folded in here). Refs #7329, #5961.

How

Each launch attempt gets an AbortController aborted at LAUNCH_TIMEOUT_MS, passed as puppeteer's signal. Aborting kills the Chrome process; the pending CDP calls then reject, the attempt has run for 20 s so it counts as stuck, and the existing retry runs. The timer is cleared when the attempt ends, so a Chrome that launched is never aborted later.

The engine's test launcher (packages/engine/src/services/__fixtures__/loopback.ts) has no retry at all; it is left as it is here.

Test plan

• Unit tests added/updated: kills and retries a launch that hangs after Chrome announced its DevTools address, with a fake launch that only settles when its signal aborts.
• Fails without the fix: with chromeTestUtils.ts from main, kills and retries a launch that hangs after Chrome announced its DevTools address fails with Error: Test timed out in 5000ms (1 failed, 7 passed). With the fix: 8 passed, 3 runs in a row.
• Real Chrome on Linux with the fix: chromeTestUtils.browser.test.ts passed, launch 1/2 ready after 92 ms.
• oxfmt and oxlint on the changed files; studio tsc --noEmit clean.
• Not reproduced on a Windows runner: the hang is intermittent there; this PR's Windows shards are the check.
• Comments follow CONTRIBUTING.md "Comments".

Size

Small on purpose: one test-launcher fix and the comment correction it absorbed. No open PR touches the studio test launcher, so there is nothing to fold it into.

[heygengenesis]

Approve at 46bfb16c. I found no blockers.

Fix. signal is a real launch option in puppeteer-core 25.11.0 (the version in bun.lock). ChromeLauncher.launch hands it to @puppeteer/browsers' Process. That registers abort → kill(), so aborting kills Chrome even while CdpBrowser._create is still waiting. Once the socket closes, the pending CDP calls reject. The catch then sees elapsed >= LAUNCH_TIMEOUT_MS and the existing retry runs. clearTimeout in finally means a Chrome that launched successfully is never aborted later. Each attempt has its own controller, so the worst case is 2 × 20 s, still under the 60 s test timeout.

Fails without the fix (checked). I ran chromeTestUtils.test.ts from the head with chromeTestUtils.ts from main. kills and retries a launch that hangs after Chrome announced its DevTools address fails with Test timed out in 5000ms (1 failed, 7 passed). With the fix, 8 passed in each of 3 runs.

Doc comment. createSessionInitBudget checks setup.idle(0), and createStallClock drops any gap over SUSPEND_GAP_MS (15 s). So a step longer than that is not charged to later steps. The new wording ("bounds each step, not setup as a whole") is accurate.

Nit, not blocking: the "Fails without the fix" line calls the test "the new test" rather than naming it. Putting the test name on that line would make it self-contained.

CI was still running when I reviewed (the Windows studio shards were in progress), with no failures so far.

[github-actions]

Edit accuracy: accurate 267 (base branch 267), smooth 132 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 (8)

• seqplainkeys-none-center-r0-nested-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): pass, passes
• seqplainkeys-none-center-r0-root-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): pass, passes
• seqplainkeys-none-center-r30-root-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): not run
• seqplainkeys-none-pct-r0-root-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): fail / pass / pass, passes
• seqplainkeys-none-pct-r30-root-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): not run
• seqplainkeys-none-px-r0-nested-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): fail / pass / pass, passes
• seqplainkeys-none-px-r30-nested-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): not run
• seqplainkeys-none-px-r30-root-z100 (fixed by studio: undo/redo on a keyframed plain element sometimes leaves the box 230-400px off (edit-accuracy seqplainkeys-none-*) #6989): not run

Unstable (2)

• 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
• seqfastkeys-none-px-r0-root-z100: tracking 0.07, pressJump 0.05, drop 0, reload 0, render 0.02, renderKey -, undo false, teleport true / tracking 0.06, pressJump 0.05, drop 0, reload 0, render 0.02, renderKey -, undo true, teleport true / tracking 0.06, pressJump 0.05, drop 0, reload 0, render 0.02, renderKey -, undo true, teleport true