Spec to working prototype — worked example

The prompt

Spec: a single-page todo list — add a task, mark it complete, delete it, and show a count of tasks remaining. Build this as one self-contained HTML artifact matching exactly that spec, nothing more.

Expected result

A working todo list artifact with add, complete, and delete wired up, plus a live remaining-count — and no extra features beyond the spec.

Why it works

This is a worked example, not a template: a real, narrow spec in, a real working prototype out, so you can see how tightly the prompt constrains scope before adapting it to your own idea.