Composition root

UseCases is the only type that constructs NoteRepositoryImpl.

clean-architectureserverpodlayer-first

lib/src/app/ is the composition root, same as the other tracks. Layer-first makes that obvious because it is the only folder that is allowed to import both infra/ and application/.

Repositories holds the store and returns NoteRepositoryImpl(store). UseCases holds the repositories, the clock, and the id generator, and returns a SaveNoteUseCase or a ListNotesUseCase.

dart

SaveNoteUseCase saveNote() => SaveNoteUseCase(
  _repositories.noteRepository(),
  clock: _clock,
  ids: _ids,
);

The endpoint calls useCases.saveNote(). A unit test does not. It constructs SaveNoteUseCase with a fake repository, which is why the use case depends on the port.

app/ has no title check and no SQL. Those stay in Note.create and the repository impl. The files are lib/src/app/use_cases.dart and lib/src/app/repositories.dart.

Next: Tests.