# Hook JSON-RPC 协议详解

所有 hook 使用 `JSON-RPC 2.0` 格式，每行一个 JSON 消息，通过 stdio 传输。

---

## 基础协议结构

### 请求（PicoClaw → Hook）

```json
{"jsonrpc":"2.0","id":1,"method":"hook.xxx","params":{...}}
```

### 响应（Hook → PicoClaw）

成功：
```json
{"jsonrpc":"2.0","id":1,"result":{...}}
```

错误：
```json
{"jsonrpc":"2.0","id":1,"error":{"code":-32000,"message":"错误信息"}}
```

---

## 1. `hook.hello`（握手）

启动时必须完成握手，否则 hook 进程会被终止。

### 请求

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "hook.hello",
  "params": {
    "name": "py_review_gate",
    "version": 1,
    "modes": ["observe", "tool", "approve"]
  }
}
```

| 字段 | 说明 |
|------|------|
| `name` | hook 名称（来自配置） |
| `version` | 协议版本，当前为 `1` |
| `modes` | hook 支持的能力模式 |

### 响应

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "result": {
    "ok": true,
    "name": "python-review-gate"
  }
}
```

---

## 2. `hook.before_llm`

在发送请求给 LLM 之前触发。可用于注入工具。

### 请求

```json
{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "hook.before_llm",
  "params": {
    "meta": {
      "AgentID": "agent-1",
      "TurnID": "turn-1",
      "ParentTurnID": "",
      "SessionKey": "session-1",
      "Iteration": 0,
      "TracePath": "runTurn",
      "Source": "turn.llm.request"
    },
    "model": "claude-sonnet",
    "messages": [
      {"role": "user", "content": "hello"}
    ],
    "tools": [
      {
        "type": "function",
        "function": {
          "name": "echo",
          "description": "echo text",
          "parameters": {"type": "object"}
        }
      }
    ],
    "options": {
      "temperature": 0.7
    },
    "channel": "cli",
    "chat_id": "chat-1",
    "graceful_terminal": false
  }
}
```

| 字段 | 说明 |
|------|------|
| `meta` | 事件元数据，用于追踪 |
| `model` | 请求的模型名称 |
| `messages` | 对话历史 |
| `tools` | 可用工具定义列表 |
| `options` | LLM 参数（temperature、max_tokens 等） |
| `channel` | 请求来源通道 |
| `chat_id` | 会话 ID |

### 响应（注入工具示例）

```json
{
  "jsonrpc": "2.0",
  "id": 2,
  "result": {
    "action": "modify",
    "request": {
      "model": "claude-sonnet",
      "messages": [{"role": "user", "content": "hello"}],
      "tools": [
        {
          "type": "function",
          "function": {
            "name": "echo",
            "description": "echo",
            "parameters": {}
          }
        },
        {
          "type": "function",
          "function": {
            "name": "my_plugin_tool",
            "description": "插件注入的工具",
            "parameters": {
              "type": "object",
              "properties": {
                "query": {"type": "string"}
              }
            }
          }
        }
      ]
    }
  }
}
```

| 字段 | 说明 |
|------|------|
| `action` | 决策动作（见下表） |
| `request` | 修改后的请求对象 |

---

## 3. `hook.after_llm`

在收到 LLM 响应后触发。可修改响应内容。

### 请求

```json
{
  "jsonrpc": "2.0",
  "id": 3,
  "method": "hook.after_llm",
  "params": {
    "meta": {
      "AgentID": "agent-1",
      "TurnID": "turn-1",
      "SessionKey": "session-1"
    },
    "model": "claude-sonnet",
    "response": {
      "role": "assistant",
      "content": "Hi!",
      "tool_calls": [
        {
          "id": "tc-1",
          "type": "function",
          "function": {
            "name": "echo",
            "arguments": "{\"text\":\"hi\"}"
          }
        }
      ]
    },
    "channel": "cli",
    "chat_id": "chat-1"
  }
}
```

### 响应

```json
{
  "jsonrpc": "2.0",
  "id": 3,
  "result": {
    "action": "continue"
  }
}
```

---

## 4. `hook.before_tool`

在执行工具前触发。可修改工具名称和参数，或拒绝执行，或直接返回结果。

### 请求

```json
{
  "jsonrpc": "2.0",
  "id": 4,
  "method": "hook.before_tool",
  "params": {
    "meta": {
      "AgentID": "agent-1",
      "TurnID": "turn-1",
      "SessionKey": "session-1"
    },
    "tool": "echo_text",
    "arguments": {
      "text": "hello"
    },
    "channel": "cli",
    "chat_id": "chat-1"
  }
}
```

| 字段 | 说明 |
|------|------|
| `tool` | 工具名称 |
| `arguments` | 工具参数 |

### 响应（改写参数）

```json
{
  "jsonrpc": "2.0",
  "id": 4,
  "result": {
    "action": "modify",
    "call": {
      "tool": "echo_text",
      "arguments": {
        "text": "modified hello"
      }
    }
  }
}
```

### 响应（拒绝执行）

```json
{
  "jsonrpc": "2.0",
  "id": 4,
  "result": {
    "action": "deny_tool",
    "reason": "参数不合法"
  }
}
```

### 响应（直接返回结果 - respond）

```json
{
  "jsonrpc": "2.0",
  "id": 4,
  "result": {
    "action": "respond",
    "call": {
      "tool": "my_plugin_tool",
      "arguments": {
        "query": "hello"
      }
    },
    "result": {
      "for_llm": "Plugin tool executed successfully",
      "for_user": "",
      "silent": false,
      "is_error": false
    }
  }
}
```

`respond` action 允许 hook 直接返回工具结果，跳过实际工具执行。适用于：
1. **插件工具注入**：外部 hook 可实现工具，无需在 ToolRegistry 注册
2. **工具结果缓存**：对重复调用返回缓存结果
3. **工具模拟**：测试时返回模拟结果

| 字段 | 说明 |
|------|------|
| `action` | 必须为 `respond` |
| `call` | 修改后的调用信息（可选） |
| `result` | 直接返回的工具结果 |

---

## 5. `hook.after_tool`

在工具执行完成后触发。可修改返回给 LLM 的结果。

### 请求

```json
{
  "jsonrpc": "2.0",
  "id": 5,
  "method": "hook.after_tool",
  "params": {
    "meta": {
      "AgentID": "agent-1",
      "TurnID": "turn-1",
      "SessionKey": "session-1"
    },
    "tool": "echo_text",
    "arguments": {
      "text": "hello"
    },
    "result": {
      "for_llm": "echoed: hello",
      "for_user": "",
      "silent": false,
      "is_error": false,
      "async": false,
      "media": [],
      "artifact_tags": [],
      "response_handled": false
    },
    "duration": 15000000,
    "channel": "cli",
    "chat_id": "chat-1"
  }
}
```

| 字段 | 说明 |
|------|------|
| `result.for_llm` | 返回给 LLM 的内容 |
| `result.for_user` | 发送给用户的内容 |
| `result.silent` | 是否静默（不发送给用户） |
| `result.is_error` | 是否为错误 |
| `result.async` | 是否异步执行 |
| `result.media` | 媒体引用列表 |
| `result.artifact_tags` | 本地产物路径标签 |
| `result.response_handled` | 是否已处理响应 |
| `duration` | 执行耗时（纳秒） |

### 响应

```json
{
  "jsonrpc": "2.0",
  "id": 5,
  "result": {
    "action": "continue"
  }
}
```

---

## 6. `hook.approve_tool`

审批型 hook，用于决定是否允许执行敏感工具。

### 请求

```json
{
  "jsonrpc": "2.0",
  "id": 6,
  "method": "hook.approve_tool",
  "params": {
    "meta": {
      "AgentID": "agent-1",
      "TurnID": "turn-1",
      "SessionKey": "session-1"
    },
    "tool": "bash",
    "arguments": {
      "command": "rm -rf /"
    },
    "channel": "cli",
    "chat_id": "chat-1"
  }
}
```

### 响应（批准）

```json
{
  "jsonrpc": "2.0",
  "id": 6,
  "result": {
    "approved": true
  }
}
```

### 响应（拒绝）

```json
{
  "jsonrpc": "2.0",
  "id": 6,
  "result": {
    "approved": false,
    "reason": "危险命令，禁止执行"
  }
}
```

---

## 7. `hook.event`（notification）

观察型事件，仅广播，无需响应。`id` 为 `0` 或不存在。

```json
{
  "jsonrpc": "2.0",
  "method": "hook.event",
  "params": {
    "Kind": "tool_exec_start",
    "Meta": {
      "AgentID": "agent-1",
      "TurnID": "turn-1"
    },
    "Payload": {
      "Tool": "echo_text",
      "Arguments": {"text": "hello"}
    }
  }
}
```

常见 `Kind` 值：
- `turn_start` / `turn_end`
- `llm_request` / `llm_response`
- `tool_exec_start` / `tool_exec_end` / `tool_exec_skipped`
- `steering_injected`
- `interrupt_received`
- `error`

---

## action 可选值

| action | 适用 hook | 效果 |
|--------|----------|------|
| `continue` | 所有拦截型 | 放行，不做修改 |
| `modify` | `before_llm`, `before_tool`, `after_llm`, `after_tool` | 改写请求/响应后放行 |
| `respond` | `before_tool` | 直接返回工具结果，跳过实际执行 |
| `deny_tool` | `before_tool` | 拒绝执行该工具 |
| `abort_turn` | 所有拦截型 | 中止当前 turn，返回错误 |
| `hard_abort` | 所有拦截型 | 强制终止整个 agent loop |

---

## 完整流程示例

```json
{"jsonrpc":"2.0","id":1,"method":"hook.hello","params":{"name":"my_hook","version":1,"modes":["tool","approve"]}}
{"jsonrpc":"2.0","id":1,"result":{"ok":true,"name":"my_hook"}}
{"jsonrpc":"2.0","id":2,"method":"hook.before_llm","params":{"model":"claude-sonnet","messages":[{"role":"user","content":"hello"}],"tools":[]}}
{"jsonrpc":"2.0","id":2,"result":{"action":"continue"}}
{"jsonrpc":"2.0","id":3,"method":"hook.before_tool","params":{"tool":"bash","arguments":{"command":"ls"}}}
{"jsonrpc":"2.0","id":3,"result":{"action":"continue"}}
{"jsonrpc":"2.0","id":4,"method":"hook.approve_tool","params":{"tool":"bash","arguments":{"command":"ls"}}}
{"jsonrpc":"2.0","id":4,"result":{"approved":true}}
{"jsonrpc":"2.0","id":5,"method":"hook.after_tool","params":{"tool":"bash","arguments":{"command":"ls"},"result":{"for_llm":"file1.txt\nfile2.txt"},"duration":5000000}}
{"jsonrpc":"2.0","id":5,"result":{"action":"continue"}}
{"jsonrpc":"2.0","id":6,"method":"hook.after_llm","params":{"model":"claude-sonnet","response":{"role":"assistant","content":"已列出文件"}}}
{"jsonrpc":"2.0","id":6,"result":{"action":"continue"}}
```

---

## 通过 `before_llm` 和 `before_tool` 实现插件工具注入

插件工具注入的标准流程：

1. 在 `before_llm` 中注入工具定义，让 LLM 知道有这个工具可用
2. 在 `before_tool` 中使用 `respond` action 直接返回工具执行结果

### `before_llm` 注入工具定义

```python
def handle_before_llm(params: dict) -> dict:
    tools = params.get("tools", [])
    
    # 添加插件工具定义
    tools.append({
        "type": "function",
        "function": {
            "name": "my_plugin_tool",
            "description": "插件提供的工具",
            "parameters": {
                "type": "object",
                "properties": {
                    "input": {"type": "string", "description": "输入内容"}
                },
                "required": ["input"]
            }
        }
    })
    
    return {
        "action": "modify",
        "request": {
            "model": params["model"],
            "messages": params["messages"],
            "tools": tools,
            "options": params.get("options", {})
        }
    }
```

### `before_tool` 返回执行结果

```python
def handle_before_tool(params: dict) -> dict:
    tool = params.get("tool", "")
    
    if tool == "my_plugin_tool":
        # 在这里实现工具逻辑
        args = params.get("arguments", {})
        input_text = args.get("input", "")
        
        # 直接返回结果，无需在 ToolRegistry 注册
        return {
            "action": "respond",
            "result": {
                "for_llm": f"插件工具执行成功，输入: {input_text}",
                "silent": False,
                "is_error": False
            }
        }
    
    return {"action": "continue"}
```

通过这种方式，外部 hook 可以完全实现插件工具，无需在 PicoClaw 内部注册任何工具实现。