Adding a new tool (a hook)

Part 4 · A SESSION, SCHEMATICALLY · Slide 59 of 60

1. hooks/<name>.sh — reads stdin with a bounded wait,
   exits 0 and prints nothing on any failure (fail open, silent)
2. Wire it in hooks.json under its event, with a timeout on
   the command object
3. Add its arms to the hooks fixture: no-hang with an idle
   stdin, and the real effect with a real payload
4. eval HOOK-CONTRACT and doctor HOOKS go green
5. It is a kernel surface: a refuter round before it ships