Addresses the two remaining 🟡 findings from the PR #758 follow-up review:
1. extract_user_id_from_token previously fell back to "default_user" when
the verified access token had no sub claim. In a multi-tenant deployment
a malformed IdP token could have bucketed every request under a single
sentinel user, risking cross-tenant data exposure. The function now
raises McpError on that branch; the BasicAuth no-token sentinel path is
preserved.
2. oauth_callback_nextcloud (Flow 2) read the PKCE code_verifier from
oauth_sessions but never deleted the row, leaving the verifier valid for
the full 10-minute TTL. The row is now deleted eagerly inside the same
branch, mirroring oauth_login_callback in browser_oauth_routes.
Also wires TOKEN_ENCRYPTION_KEY through the docker-compose step in the CI
test workflow so the integration matrix can boot — every job had been
failing fast on the ${TOKEN_ENCRYPTION_KEY:?...} interpolation guard added
in PR #758 finding 5.
Tests pin both fixes (test_token_utils_user_id.py,
test_oauth_callback_session_cleanup.py).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
