---
description: Prevent inventing APIs or ignoring real code
alwaysApply: true
---

- Base all code on the actual codebase, not assumptions.
- If a function/class/pattern might exist, search the codebase first (@Codebase or grep).
- Never use placeholder comments like “implement later”. Implement or ask.
- For external libraries: only use versions and APIs that actually exist in package.json/requirements.txt/etc.
- If the codebase has an established pattern (e.g., custom hooks, service layer), follow it exactly — never introduce a new one without asking.