{"version":"2.1.221","anchor":"tools-can-declare-a-fail-closed-permission-posture","canonical_anchor":"tools-can-declare-a-fail-closed-permission-posture","heading":"Tools can declare a fail-closed permission posture","tier":"notice","area":"Permissions","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/tools-can-declare-a-fail-closed-permission-posture","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### Tools can declare a fail-closed permission posture\n\nIf a tool's permission check crashes in plan mode, the action is now denied instead of quietly allowed.\n\n**What**\n\nA new optional tool hook decides what happens when a tool's own permission check throws, instead of the previous behaviour of logging the failure and carrying on.\n\n**Details**\n\n- The hook is `permissionCheckFailureDecision`, consulted whenever a tool's permission check raises.\n- If a tool declares one, its decision replaces the log-and-continue fallback; if the hook itself throws, the call is denied.\n- The Artifact tool uses it so that a crashed permission check in plan mode denies the action rather than letting it past the consent floor.\n\n**Evidence**\n\n`Plan-mode artifact consent floor fails closed when its permission check cannot complete`\n\n- Area: Permissions\n- Tier: You'll notice\n- Useful: 3\/5\n- Signal: 0\/5"}