**Replace Flake8 with Ruff, refactor type hints, and enhance archive processing logic**

- Removed `flake8` and `flake8-annotations` from dependencies, replaced by `ruff` for linting.
- Introduced cleaner type hinting and modern Python annotations (PEP 604 style) across multiple modules.
- Moved archive processing to a dedicated helper (`comic.archives`) for improved maintainability.
- Updated and simplified logic for archive file retrieval, directory cleaning, and user access validation.
- Improved error handling and added support for user classification restrictions in API responses.

comic/tests/test_api.py

@@ -0,0 +1,150 @@
+"""Tests for the API behaviour of the comic viewsets."""
+
+import pytest
+
+from comic import models
+
+UNKNOWN = '00000000-0000-0000-0000-000000000000'
+
+
+@pytest.mark.django_db
+def test_unknown_directory_returns_404(client, reader_user) -> None:
+    client.force_login(reader_user)
+    assert client.get(f'/api/browse/{UNKNOWN}/').status_code == 404
+
+
+@pytest.mark.django_db
+def test_unknown_selector_returns_404_in_breadcrumbs(client, reader_user) -> None:
+    client.force_login(reader_user)
+    assert client.get(f'/api/browse/{UNKNOWN}/breadcrumbs/').status_code == 404
+
+
+@pytest.mark.django_db
+def test_unknown_book_returns_404_for_an_image(client, reader_user) -> None:
+    client.force_login(reader_user)
+    assert client.get(f'/api/read/{UNKNOWN}/image/1/').status_code == 404
+
+
+@pytest.mark.django_db
+def test_image_requires_authentication(client, book) -> None:
+    assert client.get(f'/api/read/{book.selector}/image/1/').status_code == 401
+
+
+@pytest.mark.django_db
+def test_image_is_blocked_for_a_user_below_the_rating(client, book, restricted_user) -> None:
+    client.force_login(restricted_user)
+    assert client.get(f'/api/read/{book.selector}/image/1/').status_code == 403
+
+
+@pytest.mark.django_db
+def test_image_returns_the_page_for_an_allowed_user(client, book, reader_user) -> None:
+    client.force_login(reader_user)
+    response = client.get(f'/api/read/{book.selector}/image/1/')
+    assert response.status_code == 200
+    assert response['Content-Type'] == 'image/png'
+    assert b''.join(response.streaming_content)
+
+
+@pytest.mark.django_db
+def test_read_view_is_blocked_for_a_user_below_the_rating(client, book, restricted_user) -> None:
+    client.force_login(restricted_user)
+    assert client.get(f'/api/read/{book.selector}/').status_code == 403
+
+
+@pytest.mark.django_db
+def test_read_view_returns_progress_for_an_allowed_user(client, book, reader_user) -> None:
+    client.force_login(reader_user)
+    response = client.get(f'/api/read/{book.selector}/')
+    assert response.status_code == 200
+    assert response.json()['pages'] == 3
+    assert response.json()['title'] == 'issue.cbz'
+
+
+@pytest.mark.django_db
+def test_set_page_creates_the_status_and_marks_the_book_finished(client, book, reader_user) -> None:
+    client.force_login(reader_user)
+    response = client.put(
+        f'/api/read/{book.selector}/set_page/',
+        data={'page': book.page_count - 1},
+        content_type='application/json',
+    )
+    assert response.status_code == 200
+    status = models.ComicStatus.objects.get(user=reader_user, comic=book)
+    assert status.last_read_page == 2
+    assert status.finished
+    assert not status.unread
+
+
+@pytest.mark.django_db
+def test_set_page_leaves_the_book_unfinished_before_the_last_page(client, book, reader_user) -> None:
+    client.force_login(reader_user)
+    response = client.put(
+        f'/api/read/{book.selector}/set_page/',
+        data={'page': 1},
+        content_type='application/json',
+    )
+    assert response.status_code == 200
+    status = models.ComicStatus.objects.get(user=reader_user, comic=book)
+    assert not status.finished
+
+
+@pytest.mark.django_db
+def test_mark_read_records_the_last_page(client, book, reader_user) -> None:
+    client.force_login(reader_user)
+    response = client.put(
+        '/api/action/mark_read/',
+        data={'selectors': [str(book.selector)]},
+        content_type='application/json',
+    )
+    assert response.status_code == 200
+    status = models.ComicStatus.objects.get(user=reader_user, comic=book)
+    assert status.last_read_page == book.page_count - 1
+    assert status.finished
+
+
+@pytest.mark.django_db
+def test_directory_update_cascades_to_children(client, admin_user) -> None:
+    client.force_login(admin_user)
+    parent = models.Directory.objects.create(name='Parent', classification=models.Directory.Classification.C_18)
+    child = models.Directory.objects.create(name='Child', parent=parent)
+
+    response = client.put(
+        f'/api/directory/{parent.selector}/',
+        data={'classification': models.Directory.Classification.C_PG},
+        content_type='application/json',
+    )
+
+    assert response.status_code == 200
+    assert sorted(item['classification'] for item in response.json()) == [1, 1]
+    child.refresh_from_db()
+    assert child.classification == models.Directory.Classification.C_PG
+
+
+@pytest.mark.django_db
+def test_directory_partial_update_does_not_cascade(client, admin_user) -> None:
+    client.force_login(admin_user)
+    parent = models.Directory.objects.create(name='Parent', classification=models.Directory.Classification.C_18)
+    child = models.Directory.objects.create(name='Child', parent=parent)
+
+    response = client.patch(
+        f'/api/directory/{child.selector}/',
+        data={'classification': models.Directory.Classification.C_15},
+        content_type='application/json',
+    )
+
+    assert response.status_code == 200
+    assert response.json() == {'selector': str(child.selector), 'classification': 3}
+    parent.refresh_from_db()
+    assert parent.classification == models.Directory.Classification.C_18
+
+
+@pytest.mark.django_db
+def test_directory_partial_update_rejects_an_unknown_classification(client, admin_user) -> None:
+    client.force_login(admin_user)
+    directory = models.Directory.objects.create(name='Parent')
+    response = client.patch(
+        f'/api/directory/{directory.selector}/',
+        data={'classification': 9},
+        content_type='application/json',
+    )
+    assert response.status_code == 400