AI/Agent/Hook

• AI Agent Hook

  • A hook is a deterministic event handler that an AI/Agent host runs around tool execution, session lifecycle, file changes, prompting, compaction, or subagent start and stop. Where a prompt persuades, a hook always fires, and it can block.
  • Unlike Agent/Skills, hooks have no open specification. There is nothing to cite but each vendor's own reference, and the references do not agree.

  • Why hooks do not port

    • The same moment has a different name everywhere. Before a tool call is PreToolUse in Claude/Code/Hook, preToolUse in CursorAI/Hook, BeforeTool in GeminiCLI/Hook, and tool_execution_start in PiAI/Hook. Compaction is PreCompact, preCompact, and PreCompress respectively.
    • Naming is the shallow part. A mapping still cannot preserve execution timing, input schemas, blocking behavior, or output semantics — which is why Cursor describes its Claude-hook support as a subset mapping rather than compatibility.
    • Codex/Hook is the one near-match: PascalCase events that track Claude's closely, and hook commands that receive CLAUDE_PLUGIN_ROOT and CLAUDE_PLUGIN_DATA as legacy aliases.
    • Trust models diverge too. Codex will not run a non-managed plugin hook until you review and trust its exact definition, tracked by hash. PiAI/Hook and OpenCode/Hook are ordinary extension code running with full system permissions.
    • rulesync carries hooks as one of its canonical components and emits per-host representations, which is the closest thing to portability available. See AI/Coding/Tool/Plugin/Report/26/Agentic Coding Plugin Systems and Cross-Provider Portability.
  • Not to be confused with git/hook or DevContainer/Hook.

  • Examples

    • Claude/Code/Hook
    • Codex/Hook
    • CursorAI/Hook
    • GeminiCLI/Hook
    • GitHub/CoPilot/CLI/Hook
    • OpenCode/Hook
    • PiAI/Hook
    • Junie does not list hooks as an extension component.