# Before any edit on a file you haven't touched recently: py_check_syntax, get_file_slice, check the contract

### Rule 2. Verify Before Editing

Before ANY edit to a function you haven't touched recently:

1. Run: `py_check_syntax` on `src/<file>.py`
2. Get current state with `get_file_slice` (the exact lines you're about to touch)
3. Read the contract: does this function/field/method's signature, yield shape, or return type have callers I need to update?

DO NOT use `git checkout` or `git restore` to revert your way to a clean state. That destroys in-progress work. If a previous edit left the file in a broken state, ask the user.