Type-tighten
Firm up weak types and surface hidden bugs.
The prompt
Replace any/loose types in @<file> with precise types inferred from how the values are actually used. Don't change runtime behavior, and flag anything that reveals a real bug.Why it works
Tightening types from real usage often exposes latent bugs — the model is told to flag them rather than paper over them. The runtime-behavior guard keeps it a type-only change.
Fill in
@<file>— the file with loose types.
Follow-ups
- “Turn the flagged issue into a failing test, then fix it.”