Ekklesia/docs/architecture/repository-boundaries.md

# 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/*` | Domain capability, data, and the module's own UI | Module SDK, module UI SDK, public contracts, React, and external backend libraries |
| `surfaces/*` | The application shell, UI, renderers, navigation, and interaction | Surface SDK, API/auth clients, the module UI SDK and host loader, design packages, and a browser framework |
| `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 may own UI ([ADR 0021](decisions/0021-modules-as-hostable-products.md)) and authors it in
  React and TypeScript ([ADR 0022](decisions/0022-module-ui-authoring-and-host-contract.md)). A
  module may therefore contain `.tsx` source and depend on `react`, `react-dom`, and
  `@ekklesia/module-ui-sdk`. It still cannot contain `.jsx`, stylesheets, single-file components,
  Astro/Marko/MDX/HTML views, or SVG presentation assets, and cannot depend on any other UI framework
  (including `react-router-dom`, `react-native`, and `@vitejs/plugin-react`) or on shared UI-role
  packages. A module needs no bundler plugin: `@ekklesia/module-ui-build` — a `tooling` package,
  a role modules could already depend on — owns the entire module UI build
  ([ADR 0023](decisions/0023-module-ui-build-pipeline.md)). An unsupported framework aliased behind an allowed name is resolved and rejected by its
  real target.
- Module UI source is subject to the identical layer rules as module backend source: it may not
  import Core, an app, a surface, a builder, or another module. It also may not import
  `@ekklesia/module-ui-host`: that package is host infrastructure, and a module bundling the loader
  would blur the author/host split ([ADR 0024](decisions/0024-browser-safe-ui-sdk-and-host-loader.md)).
- `@ekklesia/module-ui-sdk` has no dependencies at all, and `@ekklesia/module-ui-host` depends only
  on it. Both are browser-safe by construction: neither can pull a backend type graph — and with it
  Node's global declarations — into browser code. Core still owns the containing
  application shell and all platform policy, and module UI reaches the host only through
  `@ekklesia/module-ui-sdk`.
- Manifest v6 permits independently optional primary (`entrypoints.ui`) and full-viewport display
  (`entrypoints.display`) artifacts. Modules own both feature experiences; surfaces own their
  containers, routes, navigation/chrome, credentials, error states, and publication wiring. The
  fixed authoring sources are `src/ui/index.tsx` and `src/display/index.tsx`; both use the same
  role-neutral UI SDK ABI and neither may import a surface or host loader.
- Module UI **asset publication** runs Core → `apps/api`, never the other way
  ([ADR 0025](decisions/0025-trusted-module-ui-asset-publication.md)). Core owns the policy
  (`createModuleUiPublicationRegistry`, built only from already-validated `DiscoveredModule`
  records); `apps/api` owns the HTTP route and the one canonical URL construction. Neither
  `@ekklesia/module-ui-host` nor `@ekklesia/module-ui-sdk` learns anything about how Ekklesia
  publishes artifacts — the loader takes a URL and stays host-neutral — and no module may reach
  publication internals. This introduced no new package and no boundary relaxation: `apps/*` could
  already depend on Core and on shared packages.
- A publication helper accepts module **identity** only. Neither Core's registry nor the API's URL
  builder takes a filename, relative path, or any other artifact selector, so no caller can use one
  to reach a second file inside a module package.
- A surface never imports Core or a feature module. It uses public API/client contracts, and reaches
  the server over HTTP.
- A surface may depend only on browser-safe shared roles (`api-client`, `auth-client`,
  `design-tokens`, `module-ui-host`, `module-ui-sdk`, `surface-sdk`, `ui`) plus dev-time `testing`
  and `tooling`. **`@ekklesia/contracts` is deliberately excluded**, despite being a "public
  contract" package: its barrel pulls Drizzle's types, and with them Node's global declarations, into
  any program that imports it — measured in
  [ADR 0024](decisions/0024-browser-safe-ui-sdk-and-host-loader.md), which removed exactly that
  import from `@ekklesia/module-ui-sdk` to close the browser boundary. `module-sdk` re-exports the
  same barrel and is excluded for the same reason. A surface declares its own types for the wire and
  validates what arrives ([ADR 0026](decisions/0026-minimal-ekklesia-module-ui-host.md)).
- Dashboard navigation configuration is **Core-owned platform state**, never module-owned: Core
  stores groups and placements and resolves the view, `apps/api` exposes it, and `surfaces/shell`
  renders it. A group is presentation configuration and never module structure — it has no manifest,
  version, artifact, or lifecycle, and nothing in discovery, dependency resolution, or module startup
  may ever read it
  ([ADR 0027](decisions/0027-dashboard-navigation-and-flat-modules.md)). A module's manifest declares
  its own display name and nothing about where it is presented.
- The browser host (`surfaces/shell`) statically imports no module. Every installed module UI it can
  mount arrives at run time as a URL from the module UI inventory, is fetched by the generic loader,
  and is never bundled into the shell. Its own build (esbuild, owned by that package) is a separate
  concern from `@ekklesia/module-ui-build`, which compiles a *module's* declared artifact.
- Dashboard login, logout, and session-transition UX are surface-owned
  ([ADR 0034](decisions/0034-host-owned-browser-authentication.md)). They use the API over HTTP and
  must not add credentials, cookies, tokens, or auth methods to `ModuleUiHostContext`; modules keep
  receiving only the host-neutral principal and permission hints already in the UI SDK.
- The display browser application is a separate surface entrypoint under `surfaces/shell`; it also
  statically imports no module and mounts only the exact display descriptor/artifact supplied by the
  API. It contains no Dashboard chrome and does not move display rendering into the surface—the
  module still owns that renderer.
- 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. Modules may not import another module's Drizzle tables,
  columns, relations, schema entrypoint, or migration internals.

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. ADR 0022 narrowed the guard
precisely rather than removing it: React was un-denied, every other framework stayed denied, and the
layer rules were untouched.

The Phase 3 schema validator complements source boundaries by checking table ownership, foreign-key
targets, and physical table namespaces in compiled Drizzle metadata. Offline migration validation
checks each module's packaged Drizzle inventory and policy contract, while deliberately making no
claim that opaque SQL ownership can be proven without PostgreSQL-aware analysis.

## 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.