React/TS Refactor Exercise

Goal: Refactor ReservationEditor.tsx for clarity, correctness, and maintainability.

Timebox: 60 mins live (screen share).

Deliverables:

1. A PR with incremental commits.
2. A 5–10 line DECISIONS.md explaining trade-offs.

Do: improve types, split responsibilities, fix effects, lift/reuse logic, add 1–2 focused tests, preserve behavior.

Don’t: add UI libraries, change visuals, or rewrite from scratch.

Getting started

npm i
npm run dev
# tests
npm test