Experience · Backend · Active

cs-chat api

NestJS BFF for CS Chat, owning chat persistence and same-origin product APIs while delegating auth, direct AI generation, agentic MCP replies and manual MCP tool calls to Core services.

• NestJS 11
• Prisma 7
• PostgreSQL
• class-validator
• helmet

Spec sheet

Repository path

cs-chat/apps/api

Runtime

NestJS 11 BFF

Default port

3004

Public surface

Same-origin /api on chat host

Database

cs-chat-postgres via Prisma 7

Responsibilities

• Expose chat, message, fork, auth-session, AI-provider and MCP endpoints.
• Resolve user membership through platform-auth-service.
• Call platform-ai-service for provider discovery and assistant responses when MCP is disabled.
• Create platform-agent-service executions for assistant responses that need real MCP tool use.
• Call platform-mcp-service for manual tool catalog and tool execution.
• Keep persistence in repository and Prisma modules, not in controllers.

Interfaces and contract surface

• GET /api/health
• GET /api/auth/session
• POST /api/auth/login/password
• GET /api/ai/providers
• GET /api/chats
• POST /api/chats
• PATCH /api/chats/:threadId
• POST /api/chats/:threadId/messages
• POST /api/chats/:threadId/forks
• GET /api/mcp/tools
• POST /api/internal/agent/executions/callback

Consumers

• cs-chat web

Dependencies and external touchpoints

• platform-auth-service
• platform-ai-service
• platform-agent-service
• platform-mcp-service
• @platform/contracts-agent
• cs-chat shared

Notes

• Controllers stay thin; orchestration lives in services and Core calls live in platform clients.

Source references

• cs-chat/apps/api/package.json
• cs-chat/apps/api/prisma/schema.prisma
• cs-chat/apps/api/src/chats
• cs-chat/apps/api/src/platform