Agent-agnostic hook protocol types and adapters for AI coding agents.

This crate provides the building blocks for writing hook-based middleware that works with any AI coding agent (Claude Code, Gemini CLI, Codex CLI, Amazon Q, OpenCode, Copilot CLI, etc.).

Core Concepts

• [AgentKind] identifies which agent is calling.
• HookProtocol abstracts agent-specific JSON formats.
• ToolUseHookInput and friends are the normalized input types parsed from any agent's hook JSON.
• HookOutput is a structured response type (used directly by Claude Code; other agents convert via protocol methods).
• Tool and permission-mode name resolution normalizes across agents.

Adding a New Agent

Implement HookProtocol — only two methods are required (agent and parse_tool_use). Add entries to the tool and mode alias tables in [agents] so policy evaluation uses consistent names.