fix(auth): keep SSO working when the app and API are on different ori… - #1202
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fix(auth): keep SSO working when the app and API are on different ori…#1202njbrake wants to merge 1 commit into
njbrake wants to merge 1 commit into
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…gins _Note: this PR description was drafted by Claude via back-and-forth with @njbrake. The reasoning and decisions are his; the prose is Claude's._ Fixes two SSO failures that only appear when the app and the API are served from different origins. Both are invisible in the Compose and ALB setups, where one origin proxies both. **Sign-in returns a bare `NOT_FOUND`.** Better Auth resolves its error redirect as `onAPIError.errorURL || ${baseURL}/error`, and `baseURL` is the API origin, which serves no HTML. Any auth failure lands on a blank 404 instead of the app. Now sets `onAPIError.errorURL` to `APP_URL`. **The OAuth state cookie is rejected.** `__Secure-better-auth.state` is set by the API origin and read back during a redirect initiated from the app origin, so a cross-site `SameSite=Lax` cookie is dropped and sign-in fails. `account.skipStateCookieCheck` is now enabled only when `APP_URL` and the backend origin actually differ, so single-origin deployments keep the check. PKCE still protects the exchange, and the state parameter is still round-tripped through the provider. The cookie is a second layer that a split-origin deployment cannot rely on. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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…gins
Note: this PR description was drafted by Claude via back-and-forth with @njbrake. The reasoning and decisions are his; the prose is Claude's.
Fixes two SSO failures that only appear when the app and the API are served from different origins. Both are invisible in the Compose and ALB setups, where one origin proxies both.
Sign-in returns a bare
NOT_FOUND. Better Auth resolves its error redirect asonAPIError.errorURL || ${baseURL}/error, andbaseURLis the API origin, which serves no HTML. Any auth failure lands on a blank 404 instead of the app. Now setsonAPIError.errorURLtoAPP_URL.The OAuth state cookie is rejected.
__Secure-better-auth.stateis set by the API origin and read back during a redirect initiated from the app origin, so a cross-siteSameSite=Laxcookie is dropped and sign-in fails.account.skipStateCookieCheckis now enabled only whenAPP_URLand the backend origin actually differ, so single-origin deployments keep the check.PKCE still protects the exchange, and the state parameter is still round-tripped through the provider. The cookie is a second layer that a split-origin deployment cannot rely on.