hooks

# Hooks ## Purpose Enforce a rule deterministically rather than asking the model to remember it. A hook runs every time, regardless of the model's attention, its context, or its mood — which is exactly what a rule requires. ## When to Use - A rule must hold every time: formatting, a forbidden command, a required check. - The agent keeps forgetting an instruction despite it being in the instructions. - Automating a step that should happen around every edit or command. - Blocking a dangerous action before it executes. ## Capabilities - Lifecycle events: before and after a tool call, on session start, on stop. - Deterministic enforcement: formatting, linting, blocking. - Injecting context at the right moment. - Notification and logging. ## Inputs - The rule and when it must apply. - The event that should trigger it. - What should happen when it fails: block, warn, or fix. ## Outputs - Hook configuration that runs reliably. - Rules enforced without depending on the model's memory. - A fast hook — one that does not make the agent unpleasant to use. ## Workflow 1. **Identify the rule that keeps being broken** — If an instruction is in the instruction file and is still violated, it is a hook, not an instruction. Instructions are guidance; hooks are enforcement. 2. **Choose the event** — Before a tool call to block or validate; after one to format or verify; on session start to inject context. 3. **Make it fast** — A hook runs on every matching event. Two seconds on every...