Refactor a legacy file without breaking it.

Why this works

Legacy refactors fail when the model changes behavior while making code look cleaner.

This flow makes the model describe current behavior, add characterization checks, then patch one concern at a time.

Run it

1. Ask for behavior notes

   Have Cursor summarize what the file does before editing.
2. 2
   Add characterization tests

   Cover current behavior, even if it is awkward.
3. 3
   Refactor one axis

   Rename, extract, or simplify, but never all three at once.
4. 4
   Review the diff

   Reject any change that is not tied to the stated refactor goal.

The prompt

Refactor this legacy file without changing behavior.
First summarize the current behavior and risk areas.
Then propose characterization tests.
After tests exist, make the smallest diff for one refactor axis only.

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