Openclaw Plugin Dev

Guide for creating OpenClaw plugins using hooks like llm_input and llm_output, with logging, request tracking, and config management.

OpenClaw Plugin Development Guide

Core Concepts

Hook Mechanism

OpenClaw provides various hooks to intercept and process events:

Hook	Trigger Timing	Usage
llm_input	Before an LLM request is sent	Capture requests (prompt, systemPrompt, historyMessages)
llm_output	After an LLM response is completed	Capture responses (assistantTexts, usage)
agent_start	When an Agent session starts	Initialize session state
agent_end	When an Agent session ends	Clean up resources and record statistics

Request-Response Correlation

Use runId to correlate requests and responses:

const inFlightRequests = new Map<string, RequestData>();

api.on("llm_input", (event: any) => {
  const runId = event.runId;
  inFlightRequests.set(runId, { timestamp: Date.now(), input: event });
});

api.on("llm_output", (event: any) => {
  const runId = event.runId;
  const request = inFlightRequests.get(runId);
  // Successfully paired, record the complete request-response
  inFlightRequests.delete(runId);
});

Plugin Structure

~/.openclaw/extensions/plugin-name/
├── openclaw.plugin.json    # Plugin manifest
├── index.ts                # Main entry
├── logger.ts               # Utility module (optional)
└── README.md               # Documentation (optional)

Manifest Example

{
  "id": "plugin-name",
  "name": "Plugin Name",
  "version": "1.0.0",
  "main": "index.ts",
  "description": "Plugin description"
}

Main Entry Template

type OpenClawPluginApi = {
  config?: any;
  pluginConfig?: unknown;
  logger: { info: (msg: string) => void; warn: (msg: string) => void; error: (msg: string) => void };
  on: (hookName: string, handler: (event: any, ctx?: any) => void, opts?: { priority?: number }) => void;
};

const plugin = {
  id: "plugin-name",
  name: "Plugin Name",
  description: "Plugin description",
  
  register(api: OpenClawPluginApi) {
    // Get configuration
    const config = api.config?.plugins?.entries?.["plugin-name"]?.config ?? {};
    
    // Register hooks
    api.on("llm_input", (event) => { /* Handle request */ });
    api.on("llm_output", (event) => { /* Handle response */ });
  },
};

export default plugin;

Common Patterns

Logging

// JSONL format, split files by date
const logPath = path.join(basePath, `${new Date().toISOString().split('T')[0]}.jsonl`);
fs.appendFileSync(logPath, JSON.stringify(entry) + "\n");

Configuration Management

const DEFAULT_CONFIG = {
  enabled: true,
  logPath: "~/.openclaw/logs/plugin-name",
};

const config = { ...DEFAULT_CONFIG, ...rawConfig };

Notes

Hook Lifecycle

• llm_output depends on normal session termination
• llm_output may not fire if the session is interrupted (gateway restart, user sends a new message)
• Design for interruption scenarios to avoid resource leaks

Debugging Methods

# Check gateway logs to confirm hook triggering
grep "llm_output" ~/.openclaw/logs/gateway.log

# Check plugin loading
grep "plugin-name" ~/.openclaw/logs/gateway.log

Configuration Location

Enable the plugin in openclaw.json:

{
  "plugins": {
    "entries": {
      "plugin-name": {
        "enabled": true,
        "config": {
          "option1": "value1"
        }
      }
    }
  }
}

Example: LLM API Logger

Full example available at https://github.com/cicadaFang/openclaw-llm-api-logger

Features:

• Log all LLM API requests and responses
• JSONL formatted logs, split by date
• Correlate requests and responses using runId
• Record metrics such as durationMs and usage