Address claude-review round 2 on #919:
- Anti-forgery: the `_auth_via_userinfo` allowlist-bypass flag is now sourced
ONLY from an explicit in-process `via_userinfo` argument (derived from how
the token was validated), never from the IdP payload. The payload claim is
stripped from the cached entry, so a malicious introspection/userinfo
response can't forge the bypass. Added a regression test.
- SSRF (CWE-918): guard the userinfo_uri scheme (http/https) before the request
— documents the trusted-source assumption and fails fast on misconfig.
- Introspection-unconfigured: only attempt introspection (and record its
metric) when an introspection endpoint is configured; otherwise go straight
to userinfo. Avoids mislabelled introspect-invalid metrics. Added a test.
- Tests: cache-hit test now seeds via a real first call (behavior, not cache
internals) and asserts the network is probed once; short-TTL test uses the
explicit via_userinfo arg; moved hashlib usage out.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
