Release-cycle test audit: the /mcp auth's constant-time token guard, IP keying,
ACCESS-type pinning, and brute-force message coupling were untested. Extract
behavior-preserving pure helpers so they're testable and cover them:
- sharedTokenMatches: length-mismatch early-returns before timingSafeEqual
(which throws on unequal lengths); equal-length uses timingSafeEqual; array
header -> first element; non-string -> false.
- clientIp: req.ip > socket > first XFF hop > 'unknown' (limiter keying).
- bindAccessJwtVerifier: verifyJwt pinned to JwtType.ACCESS (rejects REFRESH).
- CREDENTIALS_MISMATCH_MESSAGE single source of truth shared by
verifyUserCredentials and isCredentialsFailure, so a reworded auth error can't
silently disable the /mcp brute-force counter.
- verifyUserCredentials no-side-effect contract asserted via a TS-AST spec
(AuthService can't load under jest): its body has no createSessionAndToken/
audit/updateLastLogin while login() has all three.
Extractions are behavior-preserving (reviewed); class delegates to the helpers,
dead code + unused imports removed.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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