Implement Phases 1-5: skeleton, OAuth, categories, video sync/feed, playback

- FastAPI + PostgreSQL + Alembic + React/Vite skeleton, Docker Compose, healthcheck
- Google OAuth (single allowed account), encrypted refresh token storage
- Subscriptions sync with pagination, uploads playlist batch fetch
- Categories CRUD, many-to-many channel assignment, category filtering
- Video sync (playlistItems + videos.list batching), cached feed with cursor
  pagination, background scheduler (APScheduler)
- Video detail page with YouTube embed player
- SPA fallback routing, optimistic UI updates, client-side query caching

40 backend tests covering OAuth allow-list, sync idempotency, cascade deletes,
cursor pagination, and category filtering.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_feed.py

@@ -0,0 +1,125 @@
+from datetime import datetime, timedelta, timezone
+
+import pytest
+from fastapi.testclient import TestClient
+
+from app.core.auth_dependency import require_session
+from app.db import get_db
+from app.main import app
+from app.models.category import Category
+from app.models.channel import Channel
+from app.models.channel_category import channel_categories
+from app.models.video import Video
+
+
+@pytest.fixture
+def client(db_session):
+    def _get_db_override():
+        yield db_session
+
+    app.dependency_overrides[get_db] = _get_db_override
+    app.dependency_overrides[require_session] = lambda: None
+    with TestClient(app) as test_client:
+        yield test_client
+    del app.dependency_overrides[get_db]
+    del app.dependency_overrides[require_session]
+
+
+def _seed(db_session):
+    channel_a = Channel(youtube_channel_id="chanA", title="Channel A", subscribed=True)
+    channel_b = Channel(youtube_channel_id="chanB", title="Channel B", subscribed=True)
+    db_session.add_all([channel_a, channel_b])
+    db_session.commit()
+
+    category = Category(name="Linux", slug="linux", sort_order=0)
+    db_session.add(category)
+    db_session.commit()
+
+    db_session.execute(channel_categories.insert().values(channel_id=channel_a.id, category_id=category.id))
+    db_session.commit()
+
+    base = datetime(2026, 9, 10, tzinfo=timezone.utc)
+    videos = []
+    for i in range(5):
+        video = Video(
+            youtube_video_id=f"vid{i}",
+            channel_id=channel_a.id if i % 2 == 0 else channel_b.id,
+            title=f"Video {i}",
+            published_at=base + timedelta(hours=i),
+            youtube_url=f"https://www.youtube.com/watch?v=vid{i}",
+        )
+        videos.append(video)
+    db_session.add_all(videos)
+    db_session.commit()
+
+    return channel_a, channel_b, category, videos
+
+
+def test_feed_orders_by_published_at_desc(client, db_session):
+    _seed(db_session)
+
+    resp = client.get("/api/feed").json()
+
+    ids = [item["youtube_video_id"] for item in resp["items"]]
+    assert ids == ["vid4", "vid3", "vid2", "vid1", "vid0"]
+    assert resp["next_cursor"] is None
+
+
+def test_feed_pagination_cursor(client, db_session):
+    _seed(db_session)
+
+    page1 = client.get("/api/feed?limit=2").json()
+    assert [i["youtube_video_id"] for i in page1["items"]] == ["vid4", "vid3"]
+    assert page1["next_cursor"] is not None
+
+    page2 = client.get(f"/api/feed?limit=2&cursor={page1['next_cursor']}").json()
+    assert [i["youtube_video_id"] for i in page2["items"]] == ["vid2", "vid1"]
+    assert page2["next_cursor"] is not None
+
+    page3 = client.get(f"/api/feed?limit=2&cursor={page2['next_cursor']}").json()
+    assert [i["youtube_video_id"] for i in page3["items"]] == ["vid0"]
+    assert page3["next_cursor"] is None
+
+
+def test_feed_filters_by_category(client, db_session):
+    _, _, category, _ = _seed(db_session)
+
+    resp = client.get(f"/api/feed?category_id={category.id}").json()
+
+    ids = {i["youtube_video_id"] for i in resp["items"]}
+    assert ids == {"vid0", "vid2", "vid4"}
+
+
+def test_feed_filters_by_channel(client, db_session):
+    channel_a, channel_b, _, _ = _seed(db_session)
+
+    resp = client.get(f"/api/feed?channel_id={channel_b.id}").json()
+
+    ids = {i["youtube_video_id"] for i in resp["items"]}
+    assert ids == {"vid1", "vid3"}
+
+
+def test_feed_filters_uncategorized(client, db_session):
+    _seed(db_session)
+
+    resp = client.get("/api/feed?uncategorized=true").json()
+
+    ids = {i["youtube_video_id"] for i in resp["items"]}
+    assert ids == {"vid1", "vid3"}
+
+
+def test_feed_item_shape(client, db_session):
+    channel_a, _, category, _ = _seed(db_session)
+
+    resp = client.get("/api/feed?limit=1").json()
+    item = resp["items"][0]
+
+    assert item["channel"]["id"] == item["channel"]["id"]
+    assert set(item["channel"].keys()) == {"id", "youtube_channel_id", "title", "thumbnail_url"}
+    assert item["local"] == {
+        "available": False,
+        "status": "not_downloaded",
+        "progress_percent": None,
+        "media_url": None,
+    }
+    assert isinstance(item["categories"], list)