feat: ship persistent ai playground and alerts foundation

backend/app/services/playground_session_store.py

@@ -0,0 +1,72 @@
+from __future__ import annotations
+
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.playground_session import PlaygroundSession
+from app.schemas.ai import (
+    PlaygroundSessionResponse,
+    PlaygroundSessionState,
+    PlaygroundSessionUpsertRequest,
+)
+
+
+def _to_response(record: PlaygroundSession) -> PlaygroundSessionResponse:
+    return PlaygroundSessionResponse(
+        id=str(record.id),
+        session_key=record.session_key,
+        title=record.title,
+        state=PlaygroundSessionState.model_validate(record.state or {}),
+        created_at=record.created_at.isoformat(),
+        updated_at=record.updated_at.isoformat(),
+    )
+
+
+async def get_playground_session(
+    db: AsyncSession,
+    *,
+    user_id: int,
+    session_key: str = "default",
+) -> PlaygroundSessionResponse | None:
+    result = await db.execute(
+        select(PlaygroundSession).where(
+            PlaygroundSession.user_id == user_id,
+            PlaygroundSession.session_key == session_key,
+        )
+    )
+    record = result.scalar_one_or_none()
+    if record is None:
+        return None
+    return _to_response(record)
+
+
+async def upsert_playground_session(
+    db: AsyncSession,
+    *,
+    user_id: int,
+    payload: PlaygroundSessionUpsertRequest,
+) -> PlaygroundSessionResponse:
+    result = await db.execute(
+        select(PlaygroundSession).where(
+            PlaygroundSession.user_id == user_id,
+            PlaygroundSession.session_key == payload.session_key,
+        )
+    )
+    record = result.scalar_one_or_none()
+    title = (payload.title or payload.state.title or "Playground 会话").strip()[:200] or "Playground 会话"
+
+    if record is None:
+        record = PlaygroundSession(
+            user_id=user_id,
+            session_key=payload.session_key,
+            title=title,
+            state=payload.state.model_dump(mode="json"),
+        )
+        db.add(record)
+    else:
+        record.title = title
+        record.state = payload.state.model_dump(mode="json")
+
+    await db.flush()
+    await db.refresh(record)
+    return _to_response(record)