Update backend/internal/service/gateway_request.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

backend/internal/service/gateway_request.go

@@ -507,11 +507,15 @@ func FilterSignatureSensitiveBlocksForRetry(body []byte) []byte {
 					filtered = append(filtered, edit)
 				}
 				if len(filtered) != len(edits) {
+					if len(filtered) == 0 {
+						delete(cm, "edits")
+					} else {
 						cm["edits"] = filtered
 					}
 				}
 			}
 		}
+	}
 
 	messages, ok := req["messages"].([]any)
 	if !ok {