Problem Solving & Design B

The domain logic is cleanly separated from UI and storage, day-rollover is handled automatically, and cross-tab sync via the storage event is a thoughtful addition beyond the brief.

• +Day rollover is handled in `normalizeState`: if the stored day differs from today, the refill count is reset automatically without any user action.
• +Cross-tab synchronisation is implemented via the `storage` event, keeping two open tabs consistent without a page reload.
• +Invalid bottle sizes are silently rejected, keeping state consistent without throwing.

Completeness B+

All brief-required features are fully implemented; the only gaps are loading states (not applicable for a synchronous localStorage app) and surfacing storage errors to the user.

• +Storage errors are categorised into four distinct cases and each produces a human-readable message string in main.ts, though the measured gap notes the UI path for surfacing them is incomplete.
• +The empty state is shown or hidden based on refill count, giving first-time users a clear prompt.
• -Storage error messages are computed but the `storageStatus` element is only updated inside `render()`, which is called after a save — a load-time error (e.g.
• -There is no loading state of any kind; while localStorage reads are synchronous, the brief's measured gap flags this as a missing practice.

Technical Craft B

The codebase is well-structured with TypeScript types, named pure functions, a comprehensive automated test suite, and intentional CSS transitions with a reduced-motion override.

• +Pure domain functions (`addRefill`, `resetDay`, `getOunces`, `getProgress`) are each exported and independently testable, keeping side effects out of business logic.
• +The test suite covers motivation thresholds, storage error paths, day rollover, and cross-tab sync with a mock localStorage implementation.
• +CSS transitions are disabled wholesale when the user prefers reduced motion.
• -The `label` for the bottle-size select covers only that one control; the Refill and Reset buttons have no accessible name beyond their visible text, which is acceptable, but `aria-live` on `.metrics` means screen readers announce raw…