# Backend Rules

The backend remains derived from `domain/*.dsl` inside the existing LLM-first pipeline. No compiler platform or generator engine is introduced.

## Backend scaffold baseline

- Start backend initialization from the official NestJS CLI workspace, not from manually created files.
- The backend must remain compatible with standard Nest workspace tooling such as `nest build` and `nest start`.
- Preserve the core Nest workspace files generated by the CLI, especially:
  - `server/tsconfig.json`
  - `server/tsconfig.build.json`
  - `server/nest-cli.json`
  - `server/src/main.ts`
  - `server/src/app.module.ts`
- For domain resources, prefer official Nest CLI generation patterns for modules/controllers/services/resources and then adapt the generated code to Prisma and auth requirements.
- Do not delete required Nest workspace files just because the LLM can inline a smaller custom structure.

## Forbidden backend generation patterns

- Do not bootstrap `server/` by hand-writing a pseudo-Nest project from memory.
- Do not remove `tsconfig.json`, `tsconfig.build.json`, or `nest-cli.json` after generation.
- Do not replace standard Nest package scripts with ad hoc commands that break `nest build` or `nest start`.
- Do not continue CRUD generation on top of a degraded backend workspace without repairing the workspace first.

## Domain-derived output

- `domain/*.dsl` is the source of truth for entities, fields, primary keys, foreign keys, and enums.
- `domain-summary.json` is a derived artifact used to stabilize LLM generation and validation. It must never replace the DSL as the source of truth.
- Each entity becomes:
  - a Prisma model
  - a NestJS module
  - a controller
  - a service
  - create/update DTOs

## DTO and Prisma mapping

- `decimal` -> Prisma `Decimal`, DTO/API `string`
- `date` -> Prisma `DateTime`, DTO/API `string`
- Enums remain string-valued in DTO/API contracts

## CRUD and natural-key invariants

- CRUD routes use the real primary key name in the path.
- Every API record returned to React Admin must include `id`.
- For entities whose primary key is not `id`, the backend must map the real key to `id`.
- Natural-key list/sort logic must never build ORM `orderBy` against a fake physical `id`.

## Service invariants

- Never pass raw update DTOs into Prisma update `data`.
- Remove `id`, the real primary key, and readonly fields from update payloads before calling Prisma.
- Keep PrismaService lightweight:
  - extend `PrismaClient`
  - implement `OnModuleInit`
  - call `$connect()`
  - do not use `beforeExit`

## Reproducibility invariants

- A freshly generated backend must be bootstrappable with ordinary Nest + Prisma commands from `prompts/runtime-rules.md`.
- Missing TypeScript or Nest workspace config is a generation failure, not an acceptable simplification.
- The baseline backend should fail only on missing runtime dependencies or env values, not because the Nest workspace itself is incomplete.

## Recovery rule if backend workspace degraded

- If required Nest scaffold files are missing or broken, restore the official workspace baseline before editing Prisma models, modules, controllers, services, or DTOs.
- Treat workspace repair as higher priority than feature generation, because generated domain code on top of a broken workspace is invalid baseline output.

## Backend auth defaults

- `GET` -> `viewer | editor | admin`
- `POST`, `PATCH`, `PUT` -> `editor | admin`
- `DELETE` -> `admin`