Cloud agents and local Agent both fail the same way on a blank repo: they scaffold rooms nobody entered.
A usable slice is one job, real copy, a running surface, and the empty/error states for that job. That is the first-slice prompt.
Write the job as a sentence
Who needs what outcome in what situation. If you cannot finish that sentence, you are asking the model to invent the product.
Say what not to add
Auth, a database, and extra services are expensive defaults. They belong in the brief as exclusions unless the slice cannot work without them.
Verify in the browser
“Done” is not a file tree. It is a path a person can complete. Ask for empty, loading, and error on the main view. Ask how to run it.
The cloud-agent playbook skill is the same idea for a remote run: outcome, constraints, how to check.