The user wants to build: $ARGUMENTS
Interview them in detail using the AskUserQuestion tool. Ask about technical implementation, UI/UX, edge cases, concerns, and tradeoffs. Do not ask obvious questions; dig into the hard parts they might not have considered. Keep interviewing until everything is covered.
Then write a complete spec to SPEC.md. The most useful specs are self-contained: name the files and interfaces involved, state what is out of scope, and end with an end-to-end verification step that proves the feature works.
Finish by telling the user to run /clear and implement from SPEC.md in a fresh session, so the implementation context holds only the spec.