n8n

# MISSION: Scaffold "n8n" Production Architecture
You are an expert Senior Staff Software Architect and Full-Stack Engineer. Your mission is to scaffold and implement a production-grade, highly reliable, and modular codebase following the proven architecture of **n8n**.
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## 1. PROJECT SPECIFICATIONS & BENCHMARK
- **Reference Architecture**: n8n
- **What It Does**: n8n is a fair-code workflow automation and AI agent platform built as a TypeScript and Vue pnpm monorepo, combining a visual editor with custom-code nodes, LangChain-based AI nodes, and Model Context Protocol support.
- **Domain & Category**: Fair-Code Workflow Automation & AI Integrator
- **Production Scale**: 20+ people
- **Development Mode**: HYBRID
- **Architectural Rationale**: n8n splits its execution engine, workflow schema, and integration nodes into separate TypeORM- and Express-backed packages so the automation runtime, node library, and Vue editor can be built, tested, and versioned independently inside one Turborepo-orchestrated pnpm workspace.
- **Live Website Reference**: https://n8n.io
- **Source Repository**: https://github.com/n8n-io/n8n
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## 2. PRODUCTION TECH STACK
- **Full Stack Array**: TypeScript, Vue, Node.js, PostgreSQL, SQLite, TypeORM, LangChain, Docker, Turborepo
- **Primary Language(s)**: TypeScript, Vue, JavaScript
- **License of the reference repo**: NOASSERTION
- **Frontend**: Vue — Renders the workflow editor canvas and node panels in packages/frontend/editor-ui.; Vite — Builds the editor UI and the design-system and chat frontend packages.
- **Backend & APIs**: Node.js — Runtime for the CLI server, workers, and the newer engine service (engines >=24).; Express — HTTP server for the @n8n/engine workflow execution service.; TypeORM — ORM (as the @n8n/typeorm fork) mapping workflows, credentials, and executions to the database.
- **Data & persistence**: SQLite — Zero-config default database; the sqlite3 native module is compiled into the production Docker image.; PostgreSQL — Production database option, wired through the pg driver in the engine package.
- **Infrastructure & deploy**: Docker — Ships as multi-stage Alpine images with a separate native-module compile stage.; Turborepo — Orchestrates build, dev, and test tasks across the pnpm workspace packages.; pnpm — Workspace and dependency manager for the monorepo, with a shared version catalog.
- **Tooling, testing & ops**: LangChain — Backs the AI agent and LLM nodes via @langchain/core in the core execution package.; Model Context Protocol — Implemented by the mcp-apps package for MCP server and client node support.
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## 3. KEY ARCHITECTURAL DECISIONS (audited from https://github.com/n8n-io/n8n @ 77cd72c)
1. **Monorepo split into workflow, core, cli, and nodes-base packages**: The pnpm workspace (pnpm-workspace.yaml) separates packages/workflow (schema and expression engine), packages/core (execution primitives), packages/cli (the n8n server), and packages/nodes-base (integration nodes), letting each evolve and ship independently while Turborepo (turbo.json) coordinates builds.
2. **A newer engine package runs on Express, TypeORM, and Postgres directly**: packages/@n8n/engine/package.json declares express, @n8n/typeorm, and pg as direct dependencies alongside a testcontainers-postgresql devDependency, marking a v2 execution engine that is more tightly coupled to Postgres than the original packages/cli server.
3. **SQLite is the zero-config default; Postgres is the production path**: packages/cli test scripts default to DB_TYPE=sqlite, and docker/images/n8n/Dockerfile compiles the sqlite3 native addon into the runtime image so a single container works out of the box, while the engine package ships a pg driver for teams that need a shared production database.
4. **LangChain and MCP packages implement the AI-native workflow nodes**: packages/core/package.json depends on @langchain/core for LLM and agent nodes, and packages/@n8n/mcp-apps/package.json implements Model Context Protocol server and UI resources, matching the mcp, mcp-client, and mcp-server topics on the repository.
5. **Native modules are recompiled in a dedicated Docker build stage**: docker/images/n8n/Dockerfile adds a toolchain stage that installs python3, make, and g++ to rebuild isolated-vm and sqlite3 native addons before copying only the compiled output into the slim runtime image built from docker/images/n8n-base/Dockerfile.
6. **Design system and chat widget ship as independent Vue packages**: packages/frontend/@n8n/design-system/package.json and packages/frontend/@n8n/chat/package.json are separate Vue 3 and Vite packages built and versioned on their own, so the chat widget can be embedded outside the main editor-ui bundle.
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## 4. NON-NEGOTIABLE ARCHITECTURAL GUARDRAILS
1. **Monorepo & Modular Separation**:
   - Structure as a Turborepo monorepo with strict package boundaries:
     - `apps/web`: Application UI, routing, layouts, and server endpoints.
     - `packages/ui`: Shared design tokens, CSS variables, and Radix UI primitive components.
     - `packages/db`: Database schemas, client singleton, declarative migrations, and seed scripts.
     - `packages/config`: Shared TypeScript, ESLint, and build configurations.
2. **Strict Type Safety & Zero `any` Policy**:
   - Enable `strict: true`, `noImplicitAny: true`, and `strictNullChecks: true`.
   - Validate ALL external inputs, API request bodies, and query parameters with **Zod** schemas before execution.
3. **Frontend & Rendering Guidelines**:
   - Isolate interactive UI state to leaf components. Keep core pages lightweight and performant.
4. **Design System & Aesthetics**:
   - Keep every color, radius, shadow and font in a single token file (CSS variables) and consume tokens everywhere; never hardcode hex values in components.
   - Prefer crisp 1px borders and one subtle shadow scale over blurry default shadows. Pair one sans-serif for body/headings with one monospace for tags, badges, metrics, and code.
5. **Data Layer & Reliability**:
   - Write declarative schema definitions with foreign keys, composite indexes on queried filters, and automated timestamp triggers.
   - Use connection pooling and prepared statements for serverless database execution.
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## 5. STEP-BY-STEP SCAFFOLDING ROADMAP
- **Phase 1: Workspace & Root Config**: Initialize package manager, monorepo configuration (`turbo.json`, `tsconfig.base.json`, `package.json`).
- **Phase 2: Database Schema & Client**: Set up the data layer (SQLite, PostgreSQL): client, connection pool, models, and migration scripts.
- **Phase 3: Design Tokens & UI Primitives**: Build accessible `Button`, `Input`, `Card`, `Badge`, and layout wrappers inside `packages/ui`.
- **Phase 4: Core Application Routes & Handlers**: Implement primary authentication, user session handling, and application routes.
- **Phase 5: Quality Assurance & Build Verification**: Run `tsc --noEmit`, ESLint, Prettier, and smoke test suites to ensure zero compilation or runtime errors.
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## 6. EXECUTION INSTRUCTIONS
1. Review all specifications, architectural guardrails, and stack choices above.
2. Present the full monorepo directory tree structure.
3. Systematically generate the complete, production-ready codebase according to the 5-phase roadmap above — starting with the root workspace setup, followed by the database schema, UI design system package, and full-stack application routes until the repository is fully scaffolded and ready to run.