fix(clerk-js): store token cache expiry on the token, not the slot by Ephem · Pull Request #10429 · clerk/javascript

Ephem · 2026-10-26T17:02:21Z

Description

The stacked PR refactors and renames further and I mean to land them together.

I split them for ease of review.

This PR builds on top of #10401, see that PR for more details. It's meant to be merged into it, or after it lands.

This PR improves correctness and fixes the Known Gap in the original PR.

Problem

Since before the base PR, createdAt (base PR made it cachedAt) was stored on the cache entry, but an entry can serve a token it didn't fetch itself:

A fresher token carried over from an earlier entry (fix(clerk-js): apply session tokens monotonically on a single tab #9030), for example when #hydrateCache caches an older lastActiveToken
The same JWT cached again, through hydration or a broadcast from another tab
A replaced fetch that resolves late

Also see the new tests.

Fix

This PR moves the expiry to be stored together with the token instead. Behaviors worth knowing about:

When the same JWT is seen again, the earlier expiry wins
The token never expires later than either main or fix(clerk-js): expire cached session tokens by the earlier of exp and lifetime #10401

Other changes

baseline renamed freshest
The claims check after picking the winner could never fail, so it's removed

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

vercel · 2026-10-26T17:02:28Z

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coderabbitai · 2026-10-26T17:02:31Z

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.changeset/token-cache-expiry-on-token.md

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Walkthrough

tokenCache.ts now stores the freshest token with a fixed absolute expiry. Resolver results use bounded expiry calculations, and replaced resolvers can update freshness without resolving a pending live entry. Cache reads, refresh timers, and broadcasts use the selected token record. Tests add clock-skew, expiry, refresh, broadcast, recaching, and deferred-resolution coverage.

Priority: Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Severity of issue fixed: Medium

Possibly related PRs

clerk/javascript#10401: Changes the token expiry calculation that this cache change builds on.
clerk/javascript#10468: Changes the TokenCache contract and overlaps with freshest-token handling in the cache and broadcast paths.

Merge Risk: Minimal · up to fd102

The reviewed changes are mergeable with normal checks.

Pre-merge checks: 5

Check name	Status	Explanation
Description check		The description directly explains the token-cache expiry problem, the affected scenarios, and the proposed fix. It is clearly related to the changeset.
Title check		The title clearly summarizes the main change: moving token-cache expiry from the cache slot to the token.
Docstring Coverage		No eligible functions found in the changed files. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Documentation-only edits and deletions within survi…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

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changeset-bot · 2026-10-26T17:02:35Z

🦋 Changeset detected

Latest commit: fd102d7

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

This PR includes changesets to release 4 packages

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

Ephem · 2026-10-26T17:11:42Z

-    const prior = existing?.entry.resolvedToken;
-    value.baseline = prior ? pickFreshestJwt(existing?.baseline, prior) : existing?.baseline;
+    value.freshest = existing?.freshest;


When resolvedToken is defined, it was always guaranteed to always be the same as baseline, so the pickFreshestJwt here was unnecessary.

Note that we could make this more of a guarantee by avoiding reading from .entry.resolvedToken, but that would be a larger refactor so I left it out.

Ephem · 2026-10-26T17:13:57Z

-        if (!winnerClaims || typeof winnerClaims.exp !== 'number' || typeof winnerClaims.iat !== 'number') {
-          dropIfCurrent(live);
-          return;
-        }


This check couldn't fail. A CachedToken is only built after the isValid check earlier in the same handler, so claims.exp and claims.iat are known to be numbers. winner is always one of those records, either this resolver's candidate or a carried freshest, so winner.token always has valid claims.

The expiry math that needed exp/iat now happens when the record is built, so after picking the winner we only read winner.expiresAt. The broadcast still reads sid/org_id from the claims, but through optional chaining, so missing claims just mean no broadcast.

It couldn't fail in #10401 either: baseline and resolvedToken were only ever set to tokens that had passed isValid.

~ 🤖

Ephem · 2026-10-26T17:16:14Z

   * which is what keeps a staler resolve from overwriting a fresher token.
   */
-  baseline?: TokenResource;
+  freshest?: CachedToken;


This is still not a great name, but I couldn't come up with anything better.

How about bestKnown? It's the best token the cache has seen for this key, which can be ahead of what readers see in entry.resolvedToken while a replacement is pending.

Ephem · 2026-10-26T17:29:50Z

I think this deserves a larger refactor, but didn't want to do more than was necessary for correctness here.

wobsoriano

Appreciate the self-review 👍🏼 🚀

The device-clock expiry, min(exp, cachedAt + lifetime), was stored per cache slot and computed from that slot's cachedAt. A slot can serve a token it did not fetch, though: a fresher token carried over from an earlier slot, or the same JWT cached again via hydration or a broadcast. Its lifetime was then counted from the later slot, and on a device clock running behind, the token was served after the server stopped accepting it. Compute the expiry once, when a resolver delivers the token, from that resolver's own slot, and keep it with the token as it moves between slots. When the same JWT is seen again, the earlier expiry wins.

github-actions · 2026-10-27T19:36:58Z

API Changes Report

Generated by Break Check on 2026-10-27T20:12:18.846Z

Summary

Metric	Count
Packages analyzed	20
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.

Report generated by Break Check

_{Last ran on fd102d7.}

pkg-pr-new · 2026-10-27T19:37:24Z

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@clerk/expo-biometrics

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@clerk/expo-google-signin

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@clerk/expo-native-components

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commit: fd102d7

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Actionable comments posted: 1

🪄 Fix comments: Fix CodeRabbit comments on this PR

Prompt to fix review comments

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Inline comments:
Review comments at @packages/clerk-js/src/core/tokenCache.ts:
- Around line 339-345: Update the pre-resolved replacement handling around
`value.freshestKnown` and the resolver’s `winner === previous` check: reuse
carried expiry metadata only when its token matches `value.entry.resolvedToken`,
and compare the winner with the live entry’s resolved token before returning.
Otherwise install the winner and schedule its expiration and refresh timers.

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packages/clerk-js/src/core/__tests__/tokenCache.test.ts
packages/clerk-js/src/core/tokenCache.ts

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Ephem requested review from nikosdouvlis and wobsoriano October 26, 2026 17:02

github-actions Bot added the clerk-js label Oct 26, 2026

Ephem commented Oct 26, 2026

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Ephem mentioned this pull request Oct 26, 2026

fix(clerk-js): expire cached session tokens by the earlier of exp and lifetime #10401

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Ephem commented Oct 26, 2026

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Base automatically changed from rob/token-cache-clock-skew to main October 27, 2026 14:36

Ephem added 2 commits October 27, 2026 20:31

Clarify naming

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Ephem force-pushed the fredrik/tokens-refactor branch from 50103c3 to d28b9b9 Compare October 27, 2026 19:32

Ephem added this pull request to stack #10469 October 27, 2026 19:32

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refactor(clerk-js): refactor tokenCache for readability #10468

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Ephem merged commit 1bce44b into main Oct 28, 2026
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Ephem deleted the fredrik/tokens-refactor branch October 28, 2026 08:56

clerk-cookie mentioned this pull request Oct 28, 2026

ci(repo): Version packages #10475

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