# Backend: Overview

---
**Last Updated:** 2025-01-17  
**Phase:** Phase 0 (Planning)  
**Status:** Draft  
**Owner:** Backend Architect  
**References:**
- `/docs/project-overview.md`
- `/docs/backend/architecture.md`
- `/docs/backend/payment-flow.md`
---

## 1. Role of Backend
- Own business logic for integrations, AI capability (chat/generation/pipelines/automation), optional human feedback loops, reporting, billing, and audit.
- Integrate safely with external providers (OAuth2/webhooks, payment provider, LLM provider) and expose consistent APIs + events.
- Enforce security appropriate to your archetype (single‑ or multi‑tenant), webhook verification, and event/audit logging.

## 2. Main Domain Areas
- **Auth & Tenancy (optional):** users, roles, tenant isolation if needed.
- **Integrations / Ingestion (optional):** OAuth2/webhooks/files; connection health.
- **Core AI Module:** chat, generation, classification, RAG, or agentic automation.
- **Processing Pipeline (optional):** staged evaluation (rules/embeddings/LLM); `reasoning_trace` JSONB if used.
- **Human Feedback Loop (optional):** approvals/edits/ratings/escalations; audit trail.
- **Reporting & Exports (optional):** dashboards/summaries with history.
- **Billing (optional):** provider-hosted subscriptions/usage, webhooks.
- **Events / Audit:** `/api/events` feed for observability and downstream agents.

## 3. Integrations
- **External data providers:** OAuth2 + webhooks; signatures/verification; idempotent writes via workers.
- **Payment provider:** subscriptions, checkout/portal; webhooks for lifecycle events.
- **LLM provider:** chosen LLM API via a single helper; configurable model/params.
- **Queues:** BullMQ (Redis) for ingestion/categorization/notifications.