PaperClipAI/server/src/modules

Feature modules

A feature module under server/src/modules/<name>/ uses three layers. Each layer has one rule: which layer below it, it may import from.

adapters  →  application  →  domain

• domain/ holds pure business rules. A domain file takes plain data in and returns plain data out. A domain file must not import drizzle-orm, @paperclipai/db, a service under server/src/services/, a route under server/src/routes/, or a Node.js I/O module (node:child_process, node:fs, node:net). A domain function must not read the system clock; the caller passes now as an explicit Date value.
• application/ holds use cases and the ports they need. A use case takes its ports as constructor arguments and calls domain functions for policy decisions. An application file must not import drizzle-orm, a SQL client, a concrete adapter, or the server's HTTP error helpers. The outer service or route translates application errors into transport responses.
• adapters/ holds the concrete implementations of the ports: Postgres queries, transactions, and process control. An adapter file may import drizzle-orm, @paperclipai/db, and Node.js I/O modules.

A module exposes one entry point, index.ts, which composes the adapters and the use cases behind a factory function. Code outside the module imports only that entry point, never a file inside domain/, application/, or adapters/ directly.

pnpm check:module-boundaries enforces these rules for production source files. It also rejects imports that bypass another module's index.ts.