Architecture

Overview

The project is a monorepo managed by Turborepo with Bun workspaces. It consists of three apps and one shared package.

Tech Stack

Backend (apps/api)

Technology	Purpose
Hono	Web framework
Bun	Runtime, package manager, test runner
Prisma	ORM for PostgreSQL
Playwright	Browser automation for checking plates
Trigger.dev	Background job scheduling and execution
Sentry	Error monitoring (production only)
Scalar	Interactive API reference at /docs

Frontend (apps/web)

Technology	Purpose
Next.js	React framework (App Router)
shadcn/ui	Component library (Radix primitives)
Tailwind CSS	Utility-first styling
ReactFlow	Workflow builder canvas
Zustand	State management (builder store)
React Hook Form	Form handling with Zod integration
Axios	HTTP client with retry logic

Shared (packages/shared)

The shared package is the single source of truth for types and validation used by both apps:

Export	Description
validators	Zod schemas for license plates, users, workflows
workflow-dsl	Graph schema, node config schemas, type definitions
builder-ir	Intermediate representation schema for compiled workflows
template-variables	Variable definitions, parser, and resolver
node-registry	Node type registry with specs, ports, and config schemas
types	Shared TypeScript types (User, Check, Workflow, Execution)
constants	Limits and scheme constants

Data Flow

License Plate Check Flow

This diagram shows the network communication flow triggered by a user creating a check request with a workflow attached. Attaching a workflow to an existing check will trigger the same flow.

Database

PostgreSQL hosted on Supabase (Frankfurt region). Uses pgBouncer for connection pooling at runtime and a direct connection for migrations.

Key Models

Model	Description
User	User accounts with profile information (name, address, etc.)
CityAbbreviation	Available German cities with reservation website URLs and allowed domains
LicenseplateCheck	Individual check requests with status, scheduling info, and workflow reference
Workflow	Automation definitions with name, city, graph definition (JSON), and publish state
WorkflowExecution	Execution history with status, logs, outcome, duration, and error details