---
description: "Backend conventions for server, core, and packages"
patterns: ["packages/**/*.ts", "apps/server/**/*.ts", "apps/relay/**/*.ts", "tools/**/*.ts"]
mode: always
---

## Backend Rules

- Use Drizzle ORM for all database queries (schema in packages/core/src/schema/)
- Validate request bodies with Zod schemas
- Relations have unique constraint on (sourceId, targetId, type)
- Use `createOrGet` for idempotent relation creation
- Entity CRUD goes through Brain facade (packages/core/src/brain.ts)
- MCP tools in packages/mcp-server/src/tools/ (read-tools.ts, write-tools.ts, pipeline-tools.ts)
- REST routes in apps/server/src/routes/
- Always broadcast WebSocket events after entity/relation mutations
- Error responses: { error: string } with appropriate HTTP status
- SQLite WAL mode is always enabled