Agent Security Contract
Fail-closed pre-execution gate for agent and MCP tool calls: a YAML capability policy with a pinned catalog digest, ALLOW / BLOCK / REQUIRE_APPROVAL verdicts (exit 0/1/2), CLI, GitHub Action and HTTP sidecar, and a JSON evidence envelope (policy_sha256, trace_id, commit_sha, envelope_sha256). The envelope digest is an integrity digest, not a signature. Results in docs/EVIDENCE.md are on this corpus of 66 scenarios (33 attack, 33 benign: 0 critical false-ALLOW, 0 benign false-BLOCK).