test(js): fix flaky load fail-fast tests on slow CI runners

[manovotny]

Description

The fake-timer tests added in #9065 (describe: "when the client fetch fails or hangs at load") are flaking across unrelated PRs — two 5s timeouts on run 29305425991 and run 29413333718.

The race: load() awaits native crypto for the cookie suffix before timeLimit() schedules its initialization timer. pumpUntilSettled advanced fake time on a fixed 20-iteration budget, but crypto.subtle.digest resolves on the real event loop — fake timers can't move it. On a slow runner the digest lands after all 20 pumps have drained, the 7s fake timer sits unadvanced forever, and vitest's 5s testTimeout kills the test. That's why CI failures always report ~5015ms and local runs finish in ~17ms.

The fix teaches pumpUntilSettled to yield real event-loop turns until a fake timer is actually scheduled (or the promise settles) before spending its advance budget. No runtime code changes.

To verify, I reproduced the race deterministically by delaying crypto.subtle.digest by 200ms: exactly the two CI-flaky tests fail with the old helper, and all pass with the new one. The full file then passed 5 consecutive runs, plus 3 more with all cores saturated by busy loops.

Checklist

• pnpm test runs as expected.
• pnpm build runs as expected.
• (If applicable) JSDoc comments have been added or updated for any package exports
• (If applicable) Documentation has been updated

Type of change

• 🐛 Bug fix
• 🌟 New feature
• 🔨 Breaking change
• 📖 Refactoring / dependency upgrade / documentation
• other:

🤖 Generated with Claude Code

Summary by CodeRabbit

• Tests
  • Improved reliability of load-failure tests across slower environments and different timer states.
• Chores
  • Added release metadata for the changes included in this update.

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Project	Deployment	Actions	Updated (UTC)
clerk-js-sandbox	Ready	Preview, Comment	Jul 15, 2026 4:47pm
swingset	Ready	Preview, Comment	Jul 15, 2026 4:47pm

[changeset-bot]

🦋 Changeset detected

Latest commit: 50398eb

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 0 packages

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Repository UI (inherited)

Review profile: CHILL

Plan: Pro Plus

Run ID: af6c4727-9b6e-429e-8046-f3d9b1eccd33

📥 Commits

Reviewing files that changed from the base of the PR and between 59774c6 and 50398eb.

📒 Files selected for processing (2)

• .changeset/warm-shrimps-fall.md
• packages/clerk-js/src/core/__tests__/clerk.test.ts

---

📝 Walkthrough

Walkthrough

The PR updates pumpUntilSettled to accommodate asynchronous crypto initialization before fake timers exist, while preserving repeated 5-second timer advancement. It also adds a two-line changeset entry.

Changes

Load test timer handling

Layer / File(s)	Summary
Timer settlement helper and release metadata packages/clerk-js/src/core/__tests__/clerk.test.ts, .changeset/warm-shrimps-fall.md	The test helper yields to real event-loop turns when no timers are registered, then advances fake timers as needed; a changeset records the update.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: nikosdouvlis, brkalow

Poem

I’m a rabbit who waits for the timers to hop,
Letting crypto finish before clocks start to pop.
Five seconds at a time, the tests gently flow,
With a fresh changeset planted below.
Wiggle your nose—settled code is aglow!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: fixing flaky JavaScript load fail-fast tests on slow CI runners.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

---

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commit: 50398eb

[github-actions]

API Changes Report

Generated by Break Check on 2026-07-15T16:48:48.323Z

Summary

Metric	Count
Packages analyzed	19
Packages with changes	0
🔴 Breaking changes	0
🟡 Non-breaking changes	0
🟢 Additions	0

No API Changes Detected

All packages have stable APIs with no detected changes.

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Report generated by Break Check

_{Last ran on 50398eb.}