car-policy

Declarative policy engine for the Common Agent Runtime.

What it does

Evaluates actions against registered policy rules before execution. Policies are closures that inspect the action and current state, returning a violation reason or passing. Panicking policies are caught and treated as violations. This is the enforcement layer for agent guardrails.

Usage

use car_policy::PolicyEngine;

let mut engine = PolicyEngine::new();
engine.register("no_rm", Box::new(|action, _state| {
    if action.tool.as_deref() == Some("shell_exec") {
        Some("shell execution is forbidden".into())
    } else {
        None
    }
}), "Block shell execution");

let violations = engine.check(&action, &state);

Part of CAR -- see the main repo for full documentation.