SESSION 3 · ~60M
Hooks & automation
Hooks let your tools react to events automatically — the difference between a tool you babysit and one that runs itself.
A hook is a rule of the form 'when X happens, do Y'. In agentic tools, hooks fire on events — before or after a tool runs, when a session starts or ends, on a file save — and run code you define. They turn one-off manual steps into automatic guardrails.
Where hooks attach
- Pre-tool hooks — run before an action; can block it (e.g., forbid deleting files, block pushing to production).
- Post-tool hooks — run after an action; can format, lint, log, or trigger a follow-up.
- Session hooks — fire on session start (load context) or end (save a summary, run tests).
- Editor hooks — fire on save (auto-format, auto-test) so quality isn't a separate step.
The pattern is event-driven automation: you stop remembering to do repetitive correct things, because the hook does them for you on every triggering event. This is the same idea as a git pre-commit hook or a CI check — just attached to your AI workflow.
When to automate: only after a step is well-understood and stable. Automating a flaky or unclear process just makes it fail faster and quieter. The right sequence is manual, then habitual, then automated — not the reverse.
Guardrails as hooks: the best safety measures are automatic ones. A hook that blocks deploys without tests, or that refuses to commit secrets, protects you on the days you're tired or rushed — exactly when manual discipline fails.
TRY IT
List three things you do manually every time you finish a coding task (run tests, format, write a commit message). Pick one and imagine the hook that would do it automatically on save or on session end. That mental design is the first step to building it.
CHECK YOUR UNDERSTANDING
In what order does the module recommend establishing an automated process?
What is the primary function of a pre-tool hook in an agentic system?
Why does the module say guardrails as hooks are especially valuable?
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