Problem Solving & Design C

The calculator is well-structured with pure domain logic separated from the UI, live derived output, and a clean café aesthetic, but keyboard focus is not visibly indicated for interactive elements.

• +Results are derived directly during render rather than stored in state, so the output can never lag behind the inputs.
• +The Readout component remounts with a key change to replay a subtle settle-in animation each time the value updates.
• +The earthy palette is defined entirely in CSS custom properties, giving the app a coherent café-inspired look built on a single token set.
• -The focus-visible ring styles are defined on interactive components but the measured gap confirms keyboard focus is not visibly indicated — users navigating by keyboard cannot see which element is active.

Completeness B

All core features are present and working — inputs, ratios, water output, cup count, live updates, and reset — but the app has no empty state, no loading state, and no user-visible error surfacing beyond inline validation text.

• +All four brew methods with their correct ratios are defined in one place and drive both the dropdown and the calculations.
• +The cup count is always formatted to exactly one decimal place, matching the brief's requirement.
• +The reset button restores both fields to the same defaults used on first load via a single shared function.
• -When the grams field is empty the output silently shows 0 ml and 0.0 cups with no indication that the user needs to enter a value — there is no empty state message in the results area.
• -Validation errors from checkGrams are shown in a small hint line but the results panel still renders 0 values rather than a clear error state, so the user may not connect the hint to the blank output.

Technical Craft A

The codebase is cleanly modularised with explicit TypeScript types, a comprehensive Vitest suite covering edge cases, and pure domain functions that guard against float artifacts and invalid input.

• +A custom roundTo function eliminates binary float noise before formatting, so values like 7.999999999 display as 8.0.
• +sanitizeGramsInput strips non-numeric characters at the point of entry, preventing invalid strings from ever reaching the calculation layer.
• +The test suite covers all four brew methods, decimal precision, float artifacts, invalid inputs, and the default state in one file.