fix: only send credentials on cookie-based token refresh

[dtoxvanilla1991]

Problem

refreshToken() intermittently fails on custom domains with:

"error_description": "... includes a parameter more than once ... More than one refresh token provided."

Root cause

#204 made refreshToken.ts send credentials: "include" for any refresh on a custom domain, regardless of refreshType:

const includeCredentials =
  refreshType === RefreshType.cookie ||
  (isCustomDomain(domain) && !storageSettings.useInsecureForRefreshToken);

For the default, body-based flow (refreshType: RefreshType.refreshToken), the refresh token is already read from storage and put in the request body. Also setting credentials: "include" lets the browser attach any refresh_token cookie for that domain on top of it, so the token endpoint receives the refresh token twice - once in the body, once via the cookie - and rejects the request. This is more likely with multiple tabs open (more chances a cookie gets rotated concurrently), but can happen with a single tab too.

There's a second, related problem in checkAuth.ts. Once a cookie-backed session had accessToken/idToken/refreshToken cached in storage, checkAuth would permanently pick the body-based refresh flow (RefreshType.refreshToken) on every subsequent expiry, regardless of whether the _kbrte cookie was still present. That's exactly the scenario #204 was trying to cover: a cookie-backed session needs its httpOnly refresh cookie rotated on every refresh, but a body-based refresh can't also send that cookie without duplicating the refresh token (the bug above). Without #204's blanket credentials: "include", the cookie would go stale and break a later reload that falls back to the cookie flow with an outdated cookie value (invalid_grant).

Fix

Two changes, so both problems are resolved together instead of trading one for the other:

• refreshToken.ts: only send credentials for the cookie refresh flow, which has no body token to duplicate:

  const includeCredentials = refreshType === RefreshType.cookie;

• checkAuth.ts: compute the _kbrte cookie check and resulting refreshType once, up front, and reuse it consistently - including in the "cached tokens, but expired" branch that previously hardcoded RefreshType.refreshToken. This means a session backed by the _kbrte cookie always keeps using the cookie flow for every refresh, regardless of what's cached in storage, so the httpOnly cookie stays rotated and a credentialed body-based request (the source of the duplicate-token error) never happens for that session.

Testing

• Reworked the existing "include credentials on custom domain" test to use refreshType: RefreshType.cookie (the case it's actually meant to cover).
• Added a regression test asserting the default body-based refresh on a custom domain does not set credentials and still sends refresh_token in the body.
• Existing checkAuth.test.ts coverage (cookie present/absent, custom/non-custom domain, cached storage expired/valid) passes unchanged against the reworked flow selection.
• Full suite: 617 passed / 10 skipped. prettier --check clean.

Related

@kinde-oss/kinde-auth-react will be updated on this fix being released and the dependency bumped.

[coderabbitai]

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Walkthrough

The refresh logic now includes fetch credentials only for cookie-based refreshes. Tests cover cookie refreshes and verify that default body-based refreshes omit credentials and send the token in the request body.

Changes

Refresh credential handling

Layer / File(s)	Summary
Refresh credential behavior lib/utils/token/refreshToken.ts, lib/utils/token/refreshToken.test.ts	Cookie refreshes use credentials: "include". Default body-based refreshes omit fetch credentials and include the refresh token in the URL-encoded request body. Tests cover both behaviors on custom domains.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 91590

The refresh behavior is narrowly corrected and regression coverage covers both supported flows. One test uses a numeric enum value, creating a minor maintainability risk if enum values change, but no merge-blocking risk remains.

Suggested reviewers: coel, danielrivers, kindeshubham

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2 files.
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.
Title check	✅ Passed	The title clearly and concisely describes the main change: limiting credentials to cookie-based token refreshes.
Description check	✅ Passed	The description directly explains the duplicate-token problem, the code changes, and the related tests.

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• Commit unit tests in branch fix/refresh-token-duplicate-cookie-credentials

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✅ All modified and coverable lines are covered by tests.

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Actionable comments posted: 1

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Inline comments:
In `@lib/utils/token/refreshToken.test.ts`:
- Line 582: In the refresh token test, import RefreshType from ../../main and
replace the numeric refreshType value 1 with RefreshType.cookie so the test
explicitly targets the cookie branch.

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• lib/utils/token/refreshToken.test.ts
• lib/utils/token/refreshToken.ts

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[dtoxvanilla1991]

@CodeRabbit re-review

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@dtoxvanilla1991 I will re-review pull request #268.

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[shafaladhikari]

RefreshType is imported from ../main, which re-exports checkAuth / exchangeAuthCode, which import getRefreshType. That’s a cycle.

The unit test already imports from ../types. Please do the same here:

[shafaladhikari]

This is the behaviour the PR actually changes (cached expired tokens used to hardcode RefreshType.refreshToken), but nothing asserts refreshType on this branch.

checkAuth.test.ts “should use storage when available and token is expired” mocks getCookie to null and only checks that refreshToken was called. A regression back to always passing RefreshType.refreshToken here would still pass.

Please add a case with all three tokens in storage, isTokenExpired true, and _kbrte present, and assert:

expect(RefreshToken.refreshToken).toHaveBeenCalledWith({ domain, clientId, refreshType: RefreshType.cookie, });

The no-cookie expired path should assert RefreshType.refreshToken the same way.

[shafaladhikari]

Same nit CodeRabbit raised on the new test: please use RefreshType.cookie instead of 1.

This file still has the magic number at L359, L363, L403, L440, L474, L478, L502, L540, and L569. The new test on L583 already uses the enum — worth making these consistent while we’re here.