HealthLog/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project

HealthLog — a personal health-tracking PWA (weight, blood pressure, pulse, mood, medication compliance) with Withings integration, moodLog.app sync, Dracula-themed UI, mobile-first design, offline caching, and doctor report PDF export.

Commands

# Development
pnpm dev              # Start dev server (http://localhost:3000)
pnpm build            # Production build
pnpm lint             # ESLint
pnpm format           # Prettier format
pnpm format:check     # Prettier check
pnpm typecheck        # TypeScript strict check

# Tests
pnpm test             # Run all tests (vitest)
pnpm test:watch       # Watch mode

# Database
pnpm db:generate      # Generate Prisma client
pnpm db:migrate       # Create & apply migration (dev)
pnpm db:migrate:deploy # Apply migrations (production)
pnpm db:push          # Push schema without migration (prototyping)
pnpm db:studio        # Prisma Studio GUI

# Docker
docker compose up -d          # Start app + postgres
docker compose logs -f app    # Tail app logs

Architecture

• Next.js 16 App Router with TypeScript strict. Pages are RSC by default; "use client" only for interactivity.
• Prisma 7 ORM with PostgreSQL (25 models). Uses PrismaPg adapter from @prisma/adapter-pg. Client singleton at src/lib/db.ts. Generated client at src/generated/prisma/client (note the /client suffix). Prisma config in prisma.config.ts (not in schema.prisma).
• shadcn/ui components (new-york style) in src/components/ui/. Add new ones via pnpm dlx shadcn@latest add <component>.
• Dracula theme via CSS variables in globals.css. Dark mode is default. Use --dracula-* tokens for chart colors.
• TanStack Query for client-side data fetching. Provider in src/components/providers.tsx.
• Zod v4 (zod/v4) for all input validation (API routes and forms).
• API response envelope: { data, error, meta } via helpers in src/lib/api-response.ts.
• apiHandler wraps ALL API route handlers (src/lib/api-handler.ts) — error handling, Wide Event logging, x-request-id propagation.
• Structured Logging (Wide Events) in src/lib/logging/ — one JSON event per request/operation via WideEventBuilder + AsyncLocalStorage. Tail sampling, stdout JSON + optional Loki Push.
• Vitest for unit testing. Config in vitest.config.mts.
• pg-boss (PostgreSQL-native) for job queue: medication reminders, insight caching, weekly data backups.
• jsPDF + jspdf-autotable for client-side doctor report PDF generation (src/lib/doctor-report-pdf.ts).
• PWA offline via service worker caching strategies in public/sw.js (cache-first for static, network-first for pages, network-only for API).
• Proxy route protection — src/proxy.ts checks session cookie, enforces auth on all non-public paths. Next.js 16 uses proxy.ts (not middleware.ts).

Key Conventions

• Default locale is English. All code-level strings in English. UI text via i18n t() with German + English translations.
• Timezone: Europe/Berlin for display, UTC in database.
• Sensitive data (Withings tokens, API keys, VAPID private keys) encrypted with AES-256-GCM (src/lib/crypto.ts) before DB storage.
• Passkeys are primary auth (SimpleWebAuthn v13). Sessions stored server-side in PostgreSQL.
• All API mutations require authentication. External ingest uses Bearer token (hashed with HMAC-SHA256 keyed by API_TOKEN_HMAC_KEY).
• Rate limiting (in-memory sliding window) on auth and external-facing endpoints.

File Layout

• src/app/ — pages and API routes (App Router)
• src/components/ui/ — shadcn/ui primitives
• src/components/layout/ — shell (sidebar-nav, topbar, mobile-nav, bottom-nav)
• src/components/medications/ — medication form, card, timeline
• src/components/measurements/ — measurement form, list
• src/components/mood/ — mood form, mood list
• src/components/charts/ — Recharts wrappers
• src/lib/logging/ — Wide Events structured logging (types, config, event-builder, context, sampler, transports, background)
• src/lib/api-handler.ts — apiHandler wrapper, requireAuth(), requireAdmin(), HttpError
• src/lib/ — server utilities (db, crypto, auth, analytics, export, rate-limit, gravatar)
• src/lib/export.ts — CSV/JSON export formatting (measurements, medications, mood)
• src/lib/doctor-report-pdf.ts — client-side PDF generation (jsPDF, European medical format)
• src/lib/withings/ — Withings OAuth client and sync service
• src/lib/notifications/ — dispatcher, types, senders (telegram, ntfy, web-push)
• src/lib/jobs/ — pg-boss reminder worker (reminders, insights, data backups)
• src/lib/analytics/ — trend calculations, compliance, correlations
• src/lib/i18n/ — i18n context, config, locale detection
• src/lib/validations/ — Zod schemas shared between API + client
• src/hooks/ — React hooks (use-auth)
• messages/de.json + messages/en.json — i18n translations
• prisma/schema.prisma — database schema (25 models)
• prisma.config.ts — Prisma config (DB URL here, not in schema)
• public/sw.js — Service worker for Web Push notifications + offline caching
• docs/ — long-form audit notes (docs/audit/); end-user docs live in the separate site at https://docs.healthlog.dev
• AGENTS.md — AI agent instructions (Codex, Cursor, etc.)
• CHANGELOG.md — release notes per semver tag

Important Patterns

• Import Prisma client from @/generated/prisma/client (not @/generated/prisma)
• Prisma 7 does NOT support url = env("...") in schema.prisma — use prisma.config.ts
• Next.js 16 uses proxy.ts (not middleware.ts) — having both causes build error
• SimpleWebAuthn v13 has no @simplewebauthn/server/script/deps — define Transport type inline
• zxcvbn-typescript uses default export only (no named zxcvbnAsync/zxcvbnOptions)
• pg-boss v12: { PgBoss } named import, localConcurrency instead of teamSize, handler receives Job<T>[] array
• i18n: All UI text uses useTranslations() hook with t("section.key"). Messages in messages/en.json (English, default) + messages/de.json (German, user-selectable). Keys missing in the active locale fall back to English; missing from both surfaces the raw key — the src/lib/__tests__/i18n*.test.ts suite guards against that. Numbers/dates go through useFormatters() — never hand-roll Intl.* with a fixed locale.
• Notifications: 3 channels (Telegram, ntfy, Web Push). Dispatcher at src/lib/notifications/dispatcher.ts. Opt-out model (all events enabled by default)
• Gravatar: Server-side SHA-256 hash via src/lib/gravatar.ts. URL returned in /api/auth/me response as gravatarUrl field
• Sidebar: Collapsible (localStorage-persisted). Settings mode with section shortcuts. User section at bottom with three-dot dropdown menu
• ESLint: Strict react-hooks/set-state-in-effect rule — avoid setState inside useEffect. Use lazy useState() initializer for localStorage reads
• Proxy route protection: src/proxy.ts checks healthlog_session cookie; PUBLIC_PATHS array bypasses auth. Security headers (CSP, HSTS, X-Frame-Options) applied to all responses
• PWA safe area: Root layout has viewportFit: "cover". Bottom-nav uses pb-[env(safe-area-inset-bottom)] for iOS safe area
• Doctor report PDF: Client-side via src/lib/doctor-report-pdf.ts (jsPDF). Data from POST /api/doctor-report. European medical format, German terminology
• Achievements: Persistent in UserAchievement table. Computed on API call, new unlocks written to DB with stable unlockedAt timestamps
• Data backup: pg-boss data-backup queue runs weekly (Sundays 03:00), stores JSON in DataBackup model
• Wide Events / Structured Logging: apiHandler() wraps all API routes. Use annotate() from @/lib/logging/context for business-action annotations. Use requireAuth() / requireAdmin() from @/lib/api-handler (auto-annotates auth). Background jobs use withBackgroundEvent(). External calls tracked via getEvent()?.addExternalCall(). No console.log in production code — use event annotations instead. Env vars: LOG_LEVEL, LOG_SAMPLE_RATE, LOG_SLOW_THRESHOLD_MS, LOG_INCLUDE_STACK, LOKI_ENDPOINT, LOKI_USERNAME, LOKI_PASSWORD

Headless-Client API Patterns

The iOS app talks to bearer-protected routes while the web PWA uses cookie sessions; both share the same handlers (requireAuth() accepts either credential).

• Bearer-token issuance: POST /api/auth/login and POST /api/auth/passkey/login-verify return a token field for native clients. isNativeClientRequest() (src/lib/auth/issue-token.ts) opts in via X-Client-Type: native header or a User-Agent starting with HealthLog-iOS/. The raw hlk_<64-hex> value is returned exactly once; default lifetime 90 days, permissions ["*"].
• Token storage: API tokens are stored as HMAC-SHA-256 hashes (hashToken() in src/lib/auth/hmac.ts, keyed by env API_TOKEN_HMAC_KEY) — not plain SHA-256. The keyed HMAC defends against precomputed rainbow tables if the DB leaks. Same mechanism is reused for external-ingest token verification.
• Idempotency-Key: withIdempotency() (src/lib/idempotency.ts) wraps POST/PUT/PATCH/DELETE handlers so retries with the same Idempotency-Key (regex ^[A-Za-z0-9_\-:.]{8,128}$) for the same (userId, method, path) replay the original response with X-Idempotent-Replay: true for 24h. NOT cached: 401, 403, 408, 429, any 5xx, and any body containing hlk_ (defence against caching a token-issuing response). Validation 4xx (422 etc.) is cached so a broken retry doesn't re-hit the DB. userIdResolver defaults to the cookie session — pass a 2nd argument for Bearer-only routes.
• Device-registration cross-user-hijack guard: POST /api/devices rejects re-registration of an existing APNs token under a different user with 409 (Device token already registered to another account) instead of silently transferring ownership. APNs tokens aren't a secret, so trusting wire input would let anyone who learns a token redirect another user's pushes. Audit trail: device.register.denied with reason token_owned_by_other_user.