- Add `import hmac` to deps/auth.py imports block - Insert fgp check after user_nbf block: extract fgp_claim from payload, skip if empty (migration grace for pre-7.4 tokens, D-06), recompute fgp_actual via auth_service._compute_fgp, compare with hmac.compare_digest - Mismatch raises HTTP 401 "Token fingerprint mismatch" (D-03) - Block placed outside try/except (pure computation, no I/O, no fail-open)