fix: record fallback routing metadata

api/streaming.py

@@ -7307,6 +7307,27 @@ def _run_agent_streaming(
                     requested_model=resolved_model or model,
                     requested_provider=resolved_provider,
                 )
+                # Synthesize routing metadata from the agent's result when the
+                # hermes fallback chain switched provider/model but didn't
+                # populate llm_gateway_metadata (result carries 'model'/'provider',
+                # not 'used_model'/'used_provider' that _extract_... expects).
+                if not _gateway_routing and isinstance(result, dict):
+                    _result_model = result.get('model') or ''
+                    _result_provider = result.get('provider') or ''
+                    _req_model = resolved_model or model or ''
+                    _req_provider = resolved_provider or ''
+                    if (_result_model and _result_model != _req_model) or \
+                       (_result_provider and _req_provider and _result_provider != _req_provider):
+                        _gateway_routing = _normalize_gateway_routing_metadata(
+                            {
+                                'used_model': _result_model,
+                                'used_provider': _result_provider,
+                                'requested_model': _req_model,
+                                'requested_provider': _req_provider,
+                            },
+                            requested_model=_req_model,
+                            requested_provider=_req_provider,
+                        )
                 if _gateway_routing:
                     s.gateway_routing = _gateway_routing
                     _history = list(getattr(s, 'gateway_routing_history', None) or [])