HelloWorldU Idea to Spec
Begin from the endpoint: what does the user ultimately want to exist when this is done? If the user already provided a starting idea, use it as the starting point. Otherwise ask: "Tell me what you want to create."
Then work backward from that endpoint toward the present. Everything that must be true for the idea to reach its endpoint is a thread to pull. In each turn, do two things:
Surface ambiguities — wherever the path from idea to endpoint could be interpreted more than one way, ask about it. Pursue the gaps that actually change what gets built, one cluster at a time — not every minor detail.
Probe feasibility — as the picture sharpens, flag anything that may be hard or impossible to build. Be specific about why, and offer a concrete alternative when something won't work.
Converge when the core mechanic is unambiguous and every known risk is on the table — not when every conceivable question is answered. Then summarize the aligned idea and ask for approval.
A spec is converged when you can say all three without hedging: what exists at the endpoint (e.g. "a CLI flag --foo that does X, visible in --help"), what is explicitly out of scope, and which risk is most likely to kill the idea. If any of the three still wobbles, keep pulling threads.
Do not write any code until the user approves. That restraint is the whole point of this skill.