feat: models

app/infrastructure/db/models/like.py

@@ -0,0 +1,39 @@
+"""ORM model for likes — an append-only event log.
+
+A like/dislike is **never** updated in place. Current state for a ``(user,
+track)`` pair is the latest event by ``created_at``. This shape is required for
+future sync and as a clean ML signal (plan §4.1). Hence: no ``updated_at``,
+no unique constraint on ``(user, track)``.
+"""
+
+import datetime as dt
+import uuid
+
+from sqlalchemy import DateTime, ForeignKey, Index, String, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.infrastructure.db.base import Base
+from app.infrastructure.db.models.mixins import UUIDPrimaryKeyMixin
+
+
+class LikeModel(UUIDPrimaryKeyMixin, Base):
+    __tablename__ = "likes"
+    __table_args__ = (
+        # Latest-event lookups query by (user, track) ordered by time.
+        Index("ix_likes_user_id_track_id", "user_id", "track_id"),
+    )
+
+    user_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("users.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    track_id: Mapped[uuid.UUID] = mapped_column(
+        ForeignKey("tracks.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    value: Mapped[str] = mapped_column(String(16), nullable=False)
+    created_at: Mapped[dt.datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
+    )