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>

backend/app/models/__init__.py

@@ -0,0 +1,8 @@
+from app.models.app_settings import AppSetting
+from app.models.category import Category
+from app.models.channel import Channel
+from app.models.channel_category import channel_categories
+from app.models.oauth_credentials import OAuthCredentials
+from app.models.video import Video
+
+__all__ = ["AppSetting", "Category", "Channel", "channel_categories", "OAuthCredentials", "Video"]

backend/app/models/app_settings.py

@@ -0,0 +1,17 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class AppSetting(Base):
+    __tablename__ = "app_settings"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    key: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
+    value: Mapped[str | None] = mapped_column(String, nullable=True)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )

backend/app/models/category.py

@@ -0,0 +1,19 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, Integer, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class Category(Base):
+    __tablename__ = "categories"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    name: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
+    slug: Mapped[str] = mapped_column(String(255), unique=True, nullable=False)
+    sort_order: Mapped[int] = mapped_column(Integer, nullable=False, default=0)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )

backend/app/models/channel.py

@@ -0,0 +1,23 @@
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, String, Text, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class Channel(Base):
+    __tablename__ = "channels"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    youtube_channel_id: Mapped[str] = mapped_column(String(64), unique=True, nullable=False, index=True)
+    title: Mapped[str] = mapped_column(String(255), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    thumbnail_url: Mapped[str | None] = mapped_column(String, nullable=True)
+    uploads_playlist_id: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    subscribed: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    last_synced_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )

backend/app/models/channel_category.py

@@ -0,0 +1,10 @@
+from sqlalchemy import Column, ForeignKey, Integer, Table
+
+from app.db import Base
+
+channel_categories = Table(
+    "channel_categories",
+    Base.metadata,
+    Column("channel_id", Integer, ForeignKey("channels.id"), primary_key=True),
+    Column("category_id", Integer, ForeignKey("categories.id", ondelete="CASCADE"), primary_key=True),
+)

backend/app/models/oauth_credentials.py

@@ -0,0 +1,21 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, Integer, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+SINGLETON_ID = 1
+
+
+class OAuthCredentials(Base):
+    __tablename__ = "oauth_credentials"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    google_email: Mapped[str] = mapped_column(String(255), nullable=False)
+    encrypted_refresh_token: Mapped[str] = mapped_column(String, nullable=False)
+    access_token_expires_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )

backend/app/models/video.py

@@ -0,0 +1,24 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, Integer, String, Text, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class Video(Base):
+    __tablename__ = "videos"
+
+    id: Mapped[int] = mapped_column(primary_key=True, autoincrement=True)
+    youtube_video_id: Mapped[str] = mapped_column(String(32), unique=True, nullable=False, index=True)
+    channel_id: Mapped[int] = mapped_column(ForeignKey("channels.id"), nullable=False, index=True)
+    title: Mapped[str] = mapped_column(String(500), nullable=False)
+    description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    thumbnail_url: Mapped[str | None] = mapped_column(String, nullable=True)
+    published_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False, index=True)
+    duration_seconds: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    youtube_url: Mapped[str] = mapped_column(String, nullable=False)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )