Rules:

- Add as few additional functions or data structures as possible to achieve your goals.
- No layer violations. If a change would require moving things between compiler layers or mixing behaviour between layers, ask before making it.
- Unit tests must be randomized and property-based, and not just test exact equivalence to some value.
- If you think there's a "cleaner final boundary" for a feature or change, surface it.
- If making a specified refactor, check all files using the old version so that the refactor is done completely.