Requirements and Constraints

Say what "done" means

List the inputs and outputs, the edge cases you care about (empty input, large input, invalid data), and the constraints: language version, allowed libraries, performance limits, style rules, and files that must not change. If you leave these out, the assistant fills the gaps with its own guesses.

A specification-style prompt

Writing the edge cases explicitly also gives you the test list for later.

Write a Python function slugify(text) -> str.
- Lowercase; replace runs of non-alphanumerics with a single hyphen.
- Strip leading and trailing hyphens.
- "Hello World" -> "hello-world"; "  Python 3.12!  " -> "python-3-12"
- "" -> "" ; "--a--b--" -> "a-b"
- Standard library only. No external packages.

Say what NOT to do

Negative constraints such as "do not add new dependencies" or "do not modify the public API" prevent the most annoying surprises. Put them in a short list the assistant can check.

Quick check: Why list edge cases in the prompt?

• It slows the editor
• It makes the answer longer
• Edge cases do not matter
• So the assistant does not have to guess how to handle them