Extend First（先查书架）

A skill used once or twice gets forgotten; a library past a dozen skills is bigger than its owner's memory of it. So the third "new skill" request for the same problem does not feel like a repeat — it feels new. This skill is the librarian at the door: before anything gets built, it checks the shelf, and it checks by what the books do, not what they are called.

The gate is advisory, never a roadblock. It exists to make the overlap visible in one screen; the user always holds the veto.

Step 0 — Confirm the gate should run

Run only when the request is to create a skill, agent, or automation. Stand down, without commentary, when: