add-a-feature-safely.txt
Working code is attached. It currently does <what works today> and I
need that to keep working exactly as it does now.

Add: <the new feature>

Rules:
- Show me a diff or the changed sections only, not the whole file.
- Do not rename or restructure anything you were not asked to change.
- If the new feature genuinely requires changing existing behaviour,
  stop and tell me what and why before you write it.

Most "the AI broke my app" moments are a model helpfully modernising code you never asked it to touch. Say the working parts are off limits, every time.