feat: auth & admin

app/infrastructure/db/models/mixins.py

@@ -0,0 +1,36 @@
+"""Reusable mapped-column mixins for ORM models."""
+
+import datetime as dt
+import uuid
+
+from sqlalchemy import DateTime, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+
+class UUIDPrimaryKeyMixin:
+    """``id`` UUID primary key, generated application-side.
+
+    Generating in Python (not a DB default) keeps ids available before flush —
+    important because ``track.id`` is the client-facing ``content_id``.
+    """
+
+    id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)
+
+
+class TimestampMixin:
+    """``created_at`` / ``updated_at``, server-managed.
+
+    Present on every user-mutable entity for future delta-sync (plan §4).
+    """
+
+    created_at: Mapped[dt.datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        nullable=False,
+    )
+    updated_at: Mapped[dt.datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
+    )