modbender Message Injector
A lightweight OpenClaw workspace extension that uses the before_agent_start hook to inject custom text into every user message via prependContext.
Installation
1. Create the extension directory
mkdir -p ~/.openclaw/workspace/.openclaw/extensions/message-injector
2. Copy the plugin files
Copy scripts/index.ts and scripts/openclaw.plugin.json to the extension directory:
cp scripts/index.ts ~/.openclaw/workspace/.openclaw/extensions/message-injector/
cp scripts/openclaw.plugin.json ~/.openclaw/workspace/.openclaw/extensions/message-injector/
3. Add configuration
Add the following to ~/.openclaw/openclaw.json under plugins.entries:
"message-injector": {
"enabled": true,
"config": {
"enabled": true,
"prependText": "Your custom text here"
}
}
4. Restart Gateway
openclaw gateway restart
Configuration
| Field | Type | Default | Description |
|---|---|---|---|
enabled |
boolean | true |
Enable or disable the injector |
prependText |
string | "" |
Text to prepend before every user message |
Example Use Cases
Force memory search:
"prependText": "[⚠️ 回答前必须先 memory_search 检索相关记忆，禁止凭印象回答]"
Add persistent context:
"prependText": "[当前项目：my-app | 技术栈：React + Node.js | 部署环境：AWS]"
Inject safety rules:
"prependText": "[RULE: Always verify file paths before deletion. Never run rm -rf without confirmation.]"
How It Works
The plugin registers a before_agent_start hook. When triggered, it returns { prependContext: prependText } which OpenClaw prepends to the user's message before the agent processes it. This is a hard injection at the Gateway level — the agent cannot skip or ignore it.
Source Code
GitHub: https://github.com/Harukaon/openclaw-message-injector