Introduce your baby's foods one at a time — and the food list becomes a traffic light you can trust.
Native iOS · Korean-only UI · 100% on-device — no account, no server, no network.
Pediatric weaning guidance (질병관리청, 대한소아청소년과학회, NHS, CDC) agrees on one thing: introduce one new food at a time and watch for reactions — which can appear up to 2–3 days later — before moving on. In practice that means remembering what was fed when, what happened, and what is still untested, across months of weaning. This app is that memory: a private, offline tracker that turns the food list into a traffic light.
The full design document — data model, status derivation rules, edge cases, and scope decisions — lives at docs/design-spec.md.
The home dashboard is in the demo above; these are the rest of the screens up close.
| Foods | Food detail |
|---|---|
 |
 |
| Calendar | Log a reaction |
 |
 |
- One food at a time, enforced. Starting a new trial is blocked while another is under observation — the single rule that makes every other record trustworthy.
- Fixed 3-day observation window with gentle local check-in notifications (daytime, 09:00) and a window-end reminder.
- Traffic-light statuses — 안전 (green) / 테스트 중 (amber) / 반응 (red) / 안 먹어봄 — always derived from the trial history at read time, never stored, so the list can't drift out of sync.
- 이상 없음 one-tap check-ins log "no reaction observed" during a trial without ending it — affirmative evidence, not just absence of alarms.
- Delayed reactions handled correctly: logging a reaction on a food already marked safe flips it to red, matching how real allergies surface.
- Calendar history — month view tints each day inside a trial window and dots reaction/check-in days, with a per-day event list.
- Curated catalog of 55 Korean weaning foods with the big-9 allergen groups flagged 고위험, plus free-text custom foods.
- Doctor-ready PDF report (foods tried, statuses, reaction log) and one-tap JSON backup — both generated on device and handed to the iOS share sheet.
start a food ──▶ testing (3-day window)
│ "no reaction" check-ins (observations — never change status)
├─ log a reaction ──▶ reacted (red) · notifications cancelled
├─ mark as safe ──▶ safe (green) · window must have elapsed
├─ start next food ──▶ safe (green) · autoclose, window elapsed
└─ cancel the trial ──▶ record kept, food reverts to prior status
delayed reaction: log a reaction on an already-safe food ──▶ reacted (red)
| Layer | Choice |
|---|---|
| App | Expo SDK 57 · React Native 0.86 · TypeScript (strict) |
| Navigation | Expo Router — file-based, typed routes, stack-only |
| Data | expo-sqlite + Drizzle ORM, generated migrations committed |
| Domain logic | Pure TypeScript core, built test-first (Jest, 45 tests) |
| Notifications | expo-notifications — all local, no push service |
| Export | expo-print (PDF) · JSON backup, via the iOS share sheet |
| Localization | i18next — Korean-only by design, dates pinned to ko-KR |
| UI | Hand-rolled editorial design system (paper/ink/persimmon tokens) |
- Status is a function, not a column.
deriveStatus(trials, now)is an exhaustive switch over trial history; there is no status field to corrupt. - Pure domain core. Status rules, the start-trial decision (including implicit-safe autoclose), notification scheduling, and calendar math are side-effect-free modules with full unit coverage — the UI is a thin layer over tested logic.
- Accessible by construction. Status colors always ship with an icon + label, never color alone; touch targets meet the 44pt minimum.
- Demo fixture as code. A deterministic, invariant-tested seed
(
EXPO_PUBLIC_DEMO=1) generates 46 days of realistic history for demos and screenshots — never in real builds.
app/ Expo Router screens (stack-only, typed routes)
src/domain/ Pure logic — status, trial rules, scheduling, calendar math
src/data/ Mutations & live queries (Drizzle + useLiveQuery)
src/db/ Schema, generated migrations, seed catalog, demo fixture
src/services/ Local notifications, PDF/JSON export builders
src/ui/ Design tokens (single source of color) + shared components
npm install
npx expo run:ios # dev build on the iOS simulator
npx jest # unit tests
npx tsc --noEmit # typecheckDemo mode — boot a fresh install pre-filled with 46 days of realistic history (16 trials, reactions, check-ins, an active trial on day 2):
EXPO_PUBLIC_DEMO=1 npx expo run:iosThe demo seed only fires when the database has no baby profile; real installs are unaffected.
All data lives in a local SQLite file on the phone. There is no network code in the app — nothing is collected, synced, or sent anywhere. Export is explicit: a PDF or JSON file handed to the iOS share sheet.
MIT © 2026 Michael Ju
이 앱은 기록 보조 도구이며 의학적 조언이 아닙니다 — a tracking aid, not medical advice. Always consult your pediatrician about allergies.