fix

backend/app/api/sessions.py

@@ -14,7 +14,7 @@ from sse_starlette.sse import EventSourceResponse
 
 from app.db import get_db_dep
 from app.deps import get_current_user
-from app.engine.orchestrator import run_iteration
+from app.engine.orchestrator import generate_intro_scene, run_iteration
 from app.models import Message, Session, User, World
 from app.schemas import IterationRequest, MessageOut, SessionCreate, SessionOut
 
@@ -142,6 +142,35 @@ async def iterate_session(
     return EventSourceResponse(event_generator())
 
 
+@router.post("/{session_id}/intro")
+async def intro_session(
+    session_id: UUID,
+    db: AsyncSession = Depends(get_db_dep),
+    user: User = Depends(get_current_user),
+):
+    """SSE stream that generates the opening cinematic scene for a new session."""
+    result = await db.execute(
+        select(Session).join(World, Session.world_id == World.id).where(Session.id == session_id)
+    )
+    session = result.scalars().first()
+    if not session:
+        raise HTTPException(status_code=404, detail="session_not_found")
+    w_result = await db.execute(select(World).where(World.id == session.world_id))
+    world = w_result.scalars().first()
+    if not world or (world.owner_id != user.id and not user.is_admin):
+        raise HTTPException(status_code=403, detail="forbidden")
+
+    async def event_generator():
+        try:
+            async for event in generate_intro_scene(db=db, user_id=user.id, session_id=session_id):
+                yield {"event": event["type"], "data": json.dumps(event.get("data", {}), ensure_ascii=False, default=str)}
+        except Exception as e:
+            yield {"event": "error", "data": json.dumps({"message": str(e)}, ensure_ascii=False)}
+            yield {"event": "done", "data": "{}"}
+
+    return EventSourceResponse(event_generator())
+
+
 @router.delete("/{session_id}", status_code=204)
 async def delete_session(
     session_id: UUID,