migration: preserve mentor and llm streaming slice

app/backend/features/mentor/http.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+import json
+from http import HTTPStatus
+
+from backend.features.mentor.agent import MentorAgentError
+
+
+class MentorHttpMixin:
+    def stream_mentor_chat(self) -> None:
+        try:
+            body = self.read_json_body()
+            stream = self.application_service.mentor_stream(body)
+        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 event in stream:
+                self._write_stream_event(event)
+            self._write_stream_event({"type": "done"})
+        except (ValueError, MentorAgentError) as exc:
+            self._write_stream_event({"type": "error", "error": str(exc)})
+        except (BrokenPipeError, ConnectionResetError):
+            pass
+        finally:
+            self.close_connection = True