# Entities Layer — Innermost, Zero Dependencies

## Rules

- NEVER import from application/, infrastructure/, interface-adapters/, or di/
- NEVER import external libraries except Zod (for schema validation)
- Everything here is pure — no side effects, no I/O, no async
- Models are Zod schemas with inferred TypeScript types
- Errors are custom Error subclasses with domain-specific semantics

## Adding a New Model

1. Create `src/entities/models/{name}.ts`
2. Define Zod schema and export inferred type:
   ```typescript
   import { z } from "zod";
   export const {name}Schema = z.object({ ... });
   export type {Name} = z.infer<typeof {name}Schema>;
   ```
3. Export from `src/entities/models/index.ts`

## Adding a New Error

1. Create or edit `src/entities/errors/{domain}.ts`
2. Extend Error with constructor accepting message + options:
   ```typescript
   export class {Name}Error extends Error {
     constructor(message: string, options?: ErrorOptions) {
       super(message, options);
     }
   }
   ```
3. Export from `src/entities/errors/index.ts`