feat(storage): add storage package base

backend/packages/storage/store/persistence/drivers/postgres.py

@@ -0,0 +1,60 @@
+from __future__ import annotations
+
+import json
+
+from sqlalchemy import URL
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from store.persistence import MappedBase
+from store.persistence.shared import close_in_order
+from store.persistence.types import AppPersistence
+
+
+async def build_postgres_persistence(db_url: URL, *, echo: bool = False, pool_size: int = 5) -> AppPersistence:
+    from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
+
+    import store.repositories.models  # noqa: F401
+
+    engine = create_async_engine(
+        db_url,
+        echo=echo,
+        future=True,
+        pool_pre_ping=True,
+        pool_size=pool_size,
+        json_serializer=lambda obj: json.dumps(obj, ensure_ascii=False),
+    )
+
+    session_factory = async_sessionmaker(
+        bind=engine,
+        class_=AsyncSession,
+        expire_on_commit=False,
+        autoflush=False,
+    )
+
+    saver_cm = AsyncPostgresSaver.from_conn_string(db_url)
+    checkpointer = await saver_cm.__aenter__()
+
+    async def setup() -> None:
+        # 1. LangGraph checkpoint tables / migrations
+        await checkpointer.setup()
+
+        # 2. ORM business tables
+        async with engine.begin() as conn:
+            await conn.run_sync(MappedBase.metadata.create_all)
+
+    async def _close_saver() -> None:
+        await saver_cm.__aexit__(None, None, None)
+
+    async def aclose() -> None:
+        await close_in_order(
+            engine.dispose,
+            _close_saver,
+        )
+
+    return AppPersistence(
+        checkpointer=checkpointer,
+        engine=engine,
+        session_factory=session_factory,
+        setup=setup,
+        aclose=aclose,
+    )