Domain Builder

Inputs

• Identify the Prisma model name (PascalCase) in apps/api/prisma/schema.prisma.
• Derive naming variants:
  • Entity: PascalCase (e.g., CollectionMember)
  • entity: lowerCamel (collectionMember)
  • entity-kebab: kebab-case (collection-member)
• Decide if the domain is standalone (single entity like User) or grouped (entity + sub-entity like Collection + CollectionMember).

Workflow

1. Open apps/api/prisma/schema.prisma and locate the model. If missing, ask.
2. Split fields into user-editable vs system-managed. Treat id/createdAt/updatedAt and most foreign keys as system-managed unless requirements say otherwise. Exclude relation fields (object or array) from props.
3. Choose module layout:
   • Standalone module (User-style): packages/domain/src/{entity-kebab}/ with {entity}.schema.ts, {entity}.entity.ts, {entity}.policies.ts (optional), errors.ts, index.ts.
   • Grouped module (Collection-style): packages/domain/src/{entity-kebab}/ with schemas/, entities/, shared errors.ts, optional {entity}.policies.ts and {entity}.aggregate.ts.
4. Update packages/domain/src/{entity-kebab}/index.ts to export entities, schemas, policies, and errors.
5. Update packages/domain/src/index.ts to export the new module.

Schema files

• Import z from "zod".
• Define constants for max lengths or limits when present.
• Define {entity}Field (user-editable) and {entity}SystemField (system-managed).
• Define {entity}Fields with each field wrapped as { fieldName: schema } for route schemas.
• Define {entity}PropsSchema as z.object({ ...{entity}Field, ...{entity}SystemField }).
• Export {Entity}Props and {Entity}Snapshot types.
• Define {entity}SnapshotSchema = {entity}PropsSchema.extend({ id: z.uuid() }).
• For sub-entities, create separate schema files under schemas/ (see collection-member).

Entity files

• Import Entity, UniqueEntityID from @cookmate/core.
• Import {Entity}Props/{Entity}Snapshot and {entity}PropsSchema.
• Import Invalid{Entity}DataError from ./errors (or ../errors in grouped modules).
• Implement:
  • private constructor(props, id?)
  • static create(props, id?) => validate with {entity}PropsSchema.safeParse; throw Invalid{Entity}DataError on failure; return new {Entity}Entity(result.data, new UniqueEntityID(id))
  • getters for id and every prop
  • toSnapshot() returning { id: this.id, ...this.props }
• Add policy helpers only when required (see CollectionEntity and UserEntity).

Policies (optional)

• Create {entity}.policies.ts when there are domain rules.
• Expose pure functions that return booleans or throw domain errors.
• Keep constants (limits) in the policies file and reference them in error messages.

Errors (errors.ts)

• Import DomainError from "../errors" (or "../../errors" when nested).
• Define at minimum:
  • {Entity}NotFoundError (code: "{ENTITY}_NOT_FOUND", httpStatus 404)
  • Invalid{Entity}DataError (code: "INVALID_{ENTITY}_DATA", httpStatus 400)
• Add other errors only when requirements call for them.
• Ensure message strings are human-readable and codes are SCREAMING_SNAKE.

Mapping Prisma -> Zod

• String @db.Uuid or id fields => z.uuid()
• Fields named email => z.email()
• String => z.string().min(1).max(CONSTANT); optional/nullable => .optional().nullable()
• Int => z.number().int()
• Float/Decimal => z.number()
• Boolean => z.boolean()
• DateTime => z.date()
• Json => z.unknown()
• Enum => z.enum([...])

Local patterns

• Keep 2-space indent, 100-char line width, TypeScript ESM.
• Prefer grouping sub-entities under the same domain module when they are tightly coupled.

References

• packages/domain/src/collection/** (grouped module with schemas/, entities/, policies, aggregate, shared errors)
• packages/domain/src/user/** (standalone module with policies and errors)