safety-hook

An oh-my-pi extension that demonstrates tool_call blocking. It intercepts bash tool calls and returns { block: true, reason: "..." } when the command contains rm -rf / with normal whitespace, preventing the tool from executing.

What it demonstrates

• pi.on("tool_call", ...) — pre-execution interception
• return { block: true, reason: "..." } — blocking contract
• Regex guard on bash input (/\brm\s+-rf\s+\//)

Install

cp -r . ~/.omp/agent/extensions/safety-hook

Restart omp. The hook is active for all sessions.

Or load once:

omp --extension ./safety-hook

How it works

LLM calls bash tool
       │
       ▼
tool_call handlers run
       │
       ├─ command matches /\brm\s+-rf\s+\// ?
       │       yes → { block: true, reason: "..." }  ←  execution stops, reason sent to LLM
       │       no  → undefined                        ←  execution continues normally
       ▼
tool executes (if not blocked)

The reason text is what the LLM receives as the tool error, so it can understand why the call was rejected and try a different approach.