# Repository boundaries

These rules map platform ownership to filesystem and package boundaries. The executable check is
`pnpm boundaries`; CI must reject violations.

| Area | Owns | May depend on |
| --- | --- | --- |
| `apps/*` | Thin deployable composition roots | Public Core APIs, generated bootstrap, or a surface as required by the app |
| `core` | Feature-agnostic platform implementations | Public contracts and external infrastructure libraries |
| `modules/*` | Backend domain capability and data | Module SDK, public contracts, and external backend libraries |
| `surfaces/*` | UI, renderers, navigation, and interaction | Surface SDK, API/auth clients, public contracts, and design packages |
| `builders/*` | Declarative surface composition tooling | Builder/surface SDKs and public contracts |
| `packages/*` | Explicitly scoped SDKs, contracts, clients, design, testing, or tooling | Only dependencies appropriate to the package's declared level |
| `templates/module` | A small example backend module | The same dependencies allowed for any module |

## Mandatory rules

- Core never imports a feature module, surface, Builder implementation, or app.
- A module never imports Core implementations, another module, a surface, Builder code, or an app.
- A module cannot contain presentation source, including JSX/TSX, single-file components,
  Astro/Marko/MDX/HTML views, stylesheets, or SVG presentation assets, and cannot depend on UI
  frameworks or shared UI-role packages. Modules expose data and behavior only.
- A surface never imports Core or a feature module. It uses public API/client contracts.
- Separate surfaces do not import each other's internals.
- Builder code composes contracts and surface renderer identifiers; it does not import module or
  surface internals.
- Contract and SDK packages cannot depend upward on implementations.
- Workspace package consumers use declared `exports`, not private subpaths.
- Every internal dependency uses a `workspace:` range and every imported workspace package is
  declared by the consumer.
- Workspace aliases are forbidden because they obscure package ownership in the dependency graph.
- Workspace package names are unique and shared packages declare a recognized architectural role.
- Circular source and workspace-package dependencies are rejected.
- Cross-module data access uses services, events, capabilities, or opaque identifiers rather than
  direct table imports and foreign keys.

The boundary test suite includes intentionally invalid fixture graphs. This proves that the guard
rejects every currently machine-checkable repository rule even before production packages fill
every directory. The UI guard rejects component, view, template, stylesheet, shared UI-role, and
common UI-framework dependencies inside modules. This deny list is defense in depth; package
review remains required when adopting a new frontend technology.

Cross-module table ownership, foreign keys, and schema namespace rules require Drizzle metadata
and are intentionally deferred to the Phase 3 schema validator.

## Generated code

Generated artifacts are reproducible outputs with a named generator and validation step. A
generated module bootstrap under the root `generated/` boundary may import discovered module entry
points, and apps may import that generated bootstrap. Handwritten app and Core code still cannot
import feature modules directly. Generated files are never an excuse for a hand-maintained central
module registry.