Auth: keep the stored refresh token when a tenant switch returns none

[arnelirobles]

barakoCMS is changing POST /api/me/switch (BaryoDev/barakoCMS#1035) so a tenant switch no longer issues a second session: it returns the access token for the new tenant, and refreshToken in the response is empty. The refresh token from sign-in already covers every tenant the user belongs to, since a refresh mints for the X-Tenant it is sent and re-checks membership.

Today me.switch() stores refreshToken from the switch response as it is, so against that API it would replace the stored refresh token with "" (or undefined in the memory store), and the next refresh would fail and sign the user out.

me.switch() now keeps the stored refresh token when the response's is empty or missing, and still stores one an older API returns.

The two refresh paths (auth.refresh() and the automatic refresh on a 401) treat an empty refresh token the other way: a refresh always rotates, so the token just sent is used, and keeping it would make the next refresh a replay that revokes every session. There an empty value clears the store (signed out). Login is left as it was: a new sign-in should not inherit a previous session's refresh token.

TokenStore.set now documents that it merges: a key left out keeps its stored value. me.switch() sets only token and relies on that, and both built-in stores already behave that way.

Release order: safe to release before the barakoCMS change, because it only ignores an empty value and an older API still returns a real one (covered by a test). It needs to be out before that change ships, or a client on the current version loses its refresh token after every switch.

Tests (src/client.test.ts, "keeping the refresh token"): switch with an empty and with a missing refreshToken keeps r1, and the next refresh sends r1 with X-Tenant of the new tenant; switch against an older API still stores the returned token; explicit and automatic refresh with an empty value clear the store (the automatic one makes one refresh call and surfaces the 401); a refresh with a new value stores it.

• Before the fix: npm test exit 1 (first round 4 failed, 19 passed; second round, for the sign-out behaviour, 2 failed, 22 passed).
• After: npm run typecheck, npm test (24 passed) and npm run build all exit 0.

Summary by CodeRabbit

• Bug Fixes
  • Tenant switches now retain the existing refresh token when the response omits or returns an empty one, while using a replacement token when provided.
  • Refresh attempts that succeed without returning a refresh token now clear stored authentication and report a failure.

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📒 Files selected for processing (4)

• src/auth.ts
• src/client.test.ts
• src/resources/auth.ts
• src/resources/me.ts

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📝 Walkthrough

Walkthrough

Refresh and tenant-switch flows now retain the stored refresh token when a response omits it or returns an empty value. A non-empty refresh token from the response replaces the stored token. Tests cover tenant switching, explicit refresh, and automatic refresh.

Changes

Refresh Token Retention

Layer / File(s)	Summary
Conditional refresh-token store updates src/auth.ts, src/resources/auth.ts, src/resources/me.ts, src/client.test.ts	keepingRefreshToken omits an absent or empty refresh token from store updates. Refresh and tenant-switch flows use the helper. Tests cover retention and replacement behavior.

Priority: ➖ Normal

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

Change: Bug fix

Merge Risk: 🟡 Moderate · up to 36b47

Clients using a custom token store can lose the token needed for later refreshes. The switch and refresh return types can also mislead callers about which token they received. Resolve these contracts before merging.

Security Architecture Review

Security architecture risk: 🔵 Low · up to 36b47

The client preserves the stored refresh token across tenant switches and refreshes without changing how those requests are authenticated. The design has residual compatibility uncertainty for custom token storage and depends on server-side tenant checks that are not available here for verification.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The affected client state can be reused across tenant switches: the switched access token determines the tenant sent on later automatic refresh, while the earlier refresh token is retained. The tests demonstrate this flow for two tenants, not server authorization of it.

Trust Boundaries and Controls

• observed — The switch request still uses the stored access token for Authorization and the existing transport tenant-header path. Retaining a refresh token changes local persistence after the response, not the request’s identity or endpoint.

Resilience and Maintainability Implications

• observed — The built-in stores preserve omitted fields and expose clear as a separate operation. Automatic refresh shares concurrent recovery attempts and clears state after a non-OK refresh response; explicit refresh and switch write the store independently.

Hardening Proposals

• proposed — Define and exercise partial-update semantics for supported custom TokenStore implementations, or preserve the existing refresh token explicitly when writing to them.
• proposed — Confirm the server’s tenant-membership checks and whether an empty refresh response means no rotation; align the public response types with the confirmed switch contract.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 4 functions across 4 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
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.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the primary change: retaining the stored refresh token when a tenant switch response omits it.

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Actionable comments posted: 3

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Inline comments:
Review comments at @src/auth.ts:
- Line 14: Update keepingRefreshToken so updates passed to caller-provided
TokenStore.set preserve the currently stored refresh token when the response
omits refreshToken. Ensure replacement-based stores retain it across switch and
refresh responses.

Review comments at @src/resources/auth.ts:
- Line 59: Update the refresh response typing in the `auth.refresh` flow: define
a separate response type based on `AuthTokens` where `token` and `expiry` remain
required but refresh-token fields are optional, then use it for the `refresh()`
return type and `transport.request` generic. Keep `AuthTokens` unchanged for
complete token sets.

Review comments at @src/resources/me.ts:
- Line 28: Update the `MeResource.switch` return type and the
`transport.request` type in the switch implementation to allow `refreshToken`
and `refreshTokenExpiry` to be omitted, while keeping other `AuthTokens` fields
required. Preserve the raw response behavior and do not represent the separately
retained store token as part of the returned value.

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ℹ️ Review info

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Configuration used: defaults

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📥 Commits

Reviewing files that changed from the base of the PR and between 179edf2 and 36b476e.

📒 Files selected for processing (4)

• src/auth.ts
• src/client.test.ts
• src/resources/auth.ts
• src/resources/me.ts

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