---
name: Backend Context
description: Stack, two-listener architecture, route conventions, and auth flow for the Halo Bestie backend
type: project
---

Fastify.js REST API — single process, two HTTP listeners.

**Listeners:**
- Public `0.0.0.0:3000` → serves `client_app` + `mitra_app`
- Internal `private-ip:3001` → serves `control_center` only (never expose publicly)

**Route namespacing:**
- `/api/client/` — client app routes
- `/api/mitra/` — mitra app routes
- `/api/shared/` — shared routes (auth, lookup, etc.)
- `/internal/` — control center routes (internal listener only)

**Auth flow:**
1. Firebase Auth issues JWT on mobile/web
2. Client sends `Authorization: Bearer <token>`
3. Fastify verifies via Firebase Admin SDK
4. User fetched from PostgreSQL by Firebase UID

**Stack:** Fastify.js, PostgreSQL (GCP Cloud SQL), Firebase Admin SDK, Xendit, GCP Cloud Run

**Conventions:**
- Business logic in `services/` — never directly in route handlers
- All routes authenticated unless explicitly marked public
- Internal routes require additional `role: admin` check
- Do not mix public and internal listener route registrations
