ajayr 70d53da787
fix(auth): persist csrf_token cookie for the access_token lifetime (#3872)
The csrf_token double-submit cookie is set without max_age (a session
cookie), while the access_token cookie is persistent over HTTPS
(max_age = token_expiry_days, see _set_session_cookie). The two cookies
represent one session but had different lifetimes.

iOS Safari home-screen PWAs evict session cookies when iOS terminates the
standalone web app, but keep persistent ones. On reopen the user still
appears logged in (the persistent access_token survives and GET
/api/v1/auth/me is CSRF-exempt), but the session-only csrf_token is gone,
so the frontend's readCsrfCookie() returns null and sends no X-CSRF-Token
header. The first state-changing request then fails with 403 "CSRF token
missing. Include X-CSRF-Token header." Only re-login restored it. This
only manifests over HTTPS, which is why plain-HTTP local dev never sees it.

Give csrf_token the same max_age as access_token at both mint sites --
CSRFMiddleware (auth POSTs) and _set_csrf_cookie (OIDC GET callback) --
mirroring _set_session_cookie's `... if is_https else None` guard so the
double-submit pair always shares a lifetime: persistent together over
HTTPS, session-only together over plain HTTP.

Regression tests in tests/test_auth_type_system.py:
- test_csrf_cookie_persistent_on_https
- test_csrf_cookie_session_only_on_http
- test_oidc_callback_csrf_cookie_persistent_on_https

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-07-02 08:28:29 +08:00
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