feat: local storage logic & endpoints

app/infrastructure/db/repositories/artist_repository.py

@@ -0,0 +1,32 @@
+"""Artist repository — adapter over ``AsyncSession``."""
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.domain.entities.track import Artist
+from app.infrastructure.db.models.artist import ArtistModel
+
+
+def _to_entity(row: ArtistModel) -> Artist:
+    return Artist(
+        id=row.id,
+        name=row.name,
+        created_at=row.created_at,
+        updated_at=row.updated_at,
+    )
+
+
+class SqlAlchemyArtistRepository:
+    def __init__(self, session: AsyncSession) -> None:
+        self._session = session
+
+    async def get_or_create(self, name: str) -> Artist:
+        row = (
+            await self._session.execute(select(ArtistModel).where(ArtistModel.name == name))
+        ).scalar_one_or_none()
+        if row is None:
+            row = ArtistModel(name=name)
+            self._session.add(row)
+            await self._session.flush()
+            await self._session.refresh(row)
+        return _to_entity(row)