The per-metric assessment pipeline typed every locale as `de | en` and narrowed on the way in, so a French, Spanish, Italian or Polish account never reached a prompt with its own locale — the output-language directive could not fire and the reader got English, or German where the binary defaulted that way. Widen `SupportedLocale` to the six locales the UI ships and replace the narrowing binaries with one validating `normalizeLocale` that passes a recognised locale through unchanged and defaults an unknown value to English. The status-generate payload, status batch, status cache, comprehensive generation, the pre-generate warm passes and the forced-warm handlers all carry the full locale now. Fix the collapse sites that discarded it: the warm enqueue on the comprehensive route and the pregenerate route, the nightly batch cron, and the forced-warm job handler — the last two defaulted to German outright. The deterministic derived-score templates and the previous-context block ship de/en bodies only, so they route through `instructionLocale` (German for German readers, English otherwise) while the prompt names the reader's own language.
src/app/
The Next.js App Router tree: the page surfaces a logged-in user sees and the REST API under api/. Server components are the default; "use client" is added only where a hook, state, or browser API needs it. Routing is file-based — a page.tsx is a page, a route.ts is an API endpoint.
API routes (api/)
Every endpoint wraps its handler in apiHandler (@/lib/api-handler), parses any body with Zod safeParse, narrows userId from the session or Bearer token (never from the body), and returns the { data, error, meta? } envelope. requireAdmin() is cookie-only, so api/admin/ is unreachable by Bearer token. Notable groups:
auth/— login, register, password, passkey (WebAuthn), refresh, Codex device-OAuth.measurements/,mood-entries/,medications/,sleep/— the core health-data CRUD + batch/bulk ingest.ingest/— external Bearer-token ingest surfaces.insights/,analytics/,dashboard/— AI insights, the Coach SSE stream, trend summaries, the first-paint dashboard snapshot.withings/,whoop/,fitbit/,integrations/,sync/— OAuth connect/sync/webhook surfaces and the offline delta feed.fhir/,share-links/,doctor-report/,export/,import/— clinician-facing FHIR R4 read API, shareable records, report + data export.notifications/,devices/,send/,telegram/— channel registration, device tokens, dispatch, webhook intake.admin/— operator panel APIs (cookie-only).health/,version/,meta/,internal/— health check, build-version probe, runtime metadata, worker-internal routes.
Page surfaces
measurements/, medications/, mood/, insights/, achievements/, notifications/, settings/, onboarding/, admin/, plus the public about/, privacy/, bugreport/, the share-record route c/, and the root dashboard (page.tsx). Shared shell + chrome lives in layout.tsx; error.tsx / global-error.tsx / not-found.tsx / loading.tsx cover the framework boundaries. layout.tsx holds the one nonce-bound dangerouslySetInnerHTML (theme bootstrap).
Conventions
See ../../CLAUDE.md. The request-flow walk in .planning/codebase/arch.md annotates each layer with file:line citations. Related dirs: handlers compose ../lib/; pages render ../components/.