Kiro Hooks: .kiro/hooks JSON, PreToolUse, PostFileSave and Stop

• Workspace: .kiro/hooks/ in your project root
• Global (CLI V3): ~/.kiro/hooks/
• Any .json filename works, and one file can hold several hooks.

In the IDE you can also click + in the Agent Hooks section of the Kiro panel and pick Ask Kiro to create a hook.

• name and trigger: required. Triggers use PascalCase.
• matcher: for file events, a regex on the file path. For PreToolUse and PostToolUse, a tool ID, a category like shell or write, @mcp, @<server> or a regex.
• action.type: command or agent. Use action.command or action.prompt.
• timeout: seconds for command actions. 0 disables it.
• enabled: set to false to skip a hook without deleting it.

• UserPromptSubmit (Prompt Submit)
• Stop (Agent Stop)
• SessionStart and SessionEnd (SessionEnd is CLI V3 only)
• PreToolUse and PostToolUse
• PostFileSave, plus File Create and File Delete events
• PreTaskExec for spec tasks

Command hooks get event data as JSON on STDIN. On exit code 0, output can be added to context. In the CLI, exit code 2 blocks PreToolUse. In the IDE, any non-zero exit blocks a Pre Tool Use hook.

{
  "version": "v1",
  "hooks": [{
    "name": "Guard shell commands",
    "trigger": "PreToolUse",
    "matcher": "shell",
    "action": { "type": "command", "command": "./scripts/guard.sh" }
  }]
}

Agent prompt actions use credits because they start a new agent loop. Shell command actions do not.