Domain

In this track the entity lives at lib/features/notes/domain/. ValidationFailure lives in lib/shared/, outside the feature, so a second feature can throw the same type without importing notes.

A note has an identity, a title, and a body. Note.create is the constructor that checks the title. It trims the title and the body. A blank title throws ValidationFailure('Title is required') before any repository is involved. The row mapper rebuilds with the field constructor. The title rule has already run on create.

factory Note.create({
  required String id,
  required String title,
  required String body,
  required DateTime createdAt,
}) {
  final trimmed = title.trim();
  if (trimmed.isEmpty) {
    throw const ValidationFailure('Title is required');
  }
  return Note(
    id: id,
    title: trimmed,
    body: body.trim(),
    createdAt: createdAt,
  );
}

NoteRepository is the port: save and findAll. It returns notes, not rows. The entity is lib/features/notes/domain/note.dart. The port is lib/features/notes/domain/note_repository.dart. lib/shared/validation_failure.dart sits outside the feature so the next feature can use the same failure.

Nothing in the domain folder imports Flutter, Riverpod, Beamer, or the data implementation. That is the dependency rule for this track, same as the others.

Next: Application.