refactor: centralize ndjson streaming transport

app/backend/features/review/http.py

@@ -26,22 +26,8 @@ class ReviewHttpMixin:
         except (ValueError, json.JSONDecodeError) as exc:
             self.send_json({"error": str(exc)}, HTTPStatus.BAD_REQUEST)
             return
-        self.send_response(HTTPStatus.OK)
-        self.send_header("Content-Type", "application/x-ndjson; charset=utf-8")
-        self.send_header("Cache-Control", "no-cache, no-transform")
-        self.send_header("X-Accel-Buffering", "no")
-        self.send_header("Connection", "close")
-        self.end_headers()
-        try:
-            for chunk in stream:
-                self._write_stream_event({"type": "delta", "content": chunk})
-            self._write_stream_event({"type": "done"})
-        except (ValueError, ReviewAssistantError) as exc:
-            self._write_stream_event({"type": "error", "error": str(exc)})
-        except (BrokenPipeError, ConnectionResetError):
-            pass
-        finally:
-            self.close_connection = True
+        events = ({"type": "delta", "content": chunk} for chunk in stream)
+        self.send_ndjson_stream(events, (ValueError, ReviewAssistantError))
 
     def save_watchlist(self) -> None:
         try: