fix(clerk-js): Remove beforeunload event listener from SafeLock

[bsingerftm]

Removes the beforeunload event listener from the SafeLock function. This listener was attempting to release locks when the page unloads, but it is both redundant and harmful to user experience.

Why this listener is harmful

The beforeunload event listener disables the browser's back-forward cache (bfcache), which degrades navigation performance. As noted in the codebase itself (beforeUnloadTracker.ts:6-7):

"Ideally we should not be always listening for the beforeUnload event as it effectively disables the browser's BF cache."

This is the root cause of the UX issues reported in #7714.

Why this listener is redundant

The SafeLock function uses a dual-locking strategy:

1. Web Locks API (primary path for modern browsers)

• When navigator.locks is available in a secure context, the native Web Locks API is used
• Locks acquired via Web Locks API are automatically released when the page unloads or the async callback completes
• The beforeunload handler was calling lock.releaseLock() on the browser-tabs-lock instance, which isn't even used in this code path

2. browser-tabs-lock fallback (older browsers/non-secure contexts)

• The library has its own automatic cleanup via timeout mechanism:
• Locks are refreshed every 1000ms via refreshLockWhileAcquired()
• A lockCorrector() removes stale locks where timeRefreshed is older than 5 seconds
• The library itself does not use beforeunload internally
• When a tab closes without releasing, the lock automatically expires within ~5 seconds

Trade-off analysis

In the fallback case, other tabs may need to wait up to 5 seconds to acquire an orphaned lock. This is acceptable because:

• The lock timeout is already 5000ms (safeLock.ts:15,27)
• The poller interval is 5000ms (SessionCookiePoller.ts)
• The token cache already accounts for "SafeLock contention (~5s)" in its background refresh threshold (tokenCache.ts:111)
• This only affects the rare case of a tab closing while holding a lock

Additional benefit

This also removes a TypeScript linting issue (@typescript-eslint/no-misused-promises) where an async function was used as an event handler without proper promise handling.

🐛 Bug fix (fixes #7714)

Summary by CodeRabbit

• Bug Fixes
  • Removed an unload handler that could trigger "Leave site?" prompts and interfere with browser back/forward cache, improving navigation and page restoration while preserving existing lock behavior.

[changeset-bot]

🦋 Changeset detected

Latest commit: 9c9b70f

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

This PR includes changesets to release 3 packages

Name	Type
@clerk/clerk-js	Patch
@clerk/chrome-extension	Patch
@clerk/expo	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[vercel]

@claude is attempting to deploy a commit to the Clerk Production Team on Vercel.

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[coderabbitai]

📝 Walkthrough

Walkthrough

Removed the beforeunload event listener from the SafeLock implementation in the authentication module; the listener that previously called lock.releaseLock(key) on page unload is no longer registered. The lock acquisition and release logic otherwise remains unchanged: it still prefers the navigator.locks API when available and falls back to the browser-tabs-lock mechanism. The public signature SafeLock(key: string) is unchanged.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Linked Issues check	✅ Passed	The PR fully addresses #7714's requirement to remove the beforeunload listener that was degrading browser navigation performance and disabling bfcache.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to removing the beforeunload listener from SafeLock and updating the changelog; no unrelated modifications present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Title check	✅ Passed	The title accurately and concisely summarizes the main change: removing the beforeunload event listener from SafeLock, which is the primary focus of the changeset and directly addresses the performance issue described in the PR objectives.

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[nikosdouvlis]

Makes sense, I verified the claims against the library source, thank you

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In @.changeset/remove-beforeunload-safelock.md:
- Line 5: Update the changelog entry to remove the unsupported claim about
triggering "Leave site?" prompts and instead state that the removed window
"beforeunload" listener in SafeLock caused bfcache disablement; reference the
SafeLock component and the removed beforeunload handler (which called
lock.releaseLock(key)) so the description clearly attributes the change to
bfcache impact and not to prompt behavior, and optionally mention issue `#7714`
for context.

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commit: 17726af