fix: improve MiniMax code plan integration (#1169)

This PR improves MiniMax Code Plan integration in DeerFlow by fixing three issues in the current flow: stream errors were not clearly surfaced in the UI, the frontend could not display the actual provider model ID, and MiniMax reasoning output could leak into final assistant content as inline <think>...</think>. The change adds a MiniMax-specific adapter, exposes real model IDs end-to-end, and adds a frontend fallback for historical messages.
Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

frontend/src/core/threads/hooks.ts

@@ -31,6 +31,29 @@ export type ThreadStreamOptions = {
   onToolEnd?: (event: ToolEndEvent) => void;
 };
 
+function getStreamErrorMessage(error: unknown): string {
+  if (typeof error === "string" && error.trim()) {
+    return error;
+  }
+  if (error instanceof Error && error.message.trim()) {
+    return error.message;
+  }
+  if (typeof error === "object" && error !== null) {
+    const message = Reflect.get(error, "message");
+    if (typeof message === "string" && message.trim()) {
+      return message;
+    }
+    const nestedError = Reflect.get(error, "error");
+    if (nestedError instanceof Error && nestedError.message.trim()) {
+      return nestedError.message;
+    }
+    if (typeof nestedError === "string" && nestedError.trim()) {
+      return nestedError;
+    }
+  }
+  return "Request failed.";
+}
+
 export function useThreadStream({
   threadId,
   context,
@@ -148,6 +171,10 @@ export function useThreadStream({
         updateSubtask({ id: e.task_id, latestMessage: e.message });
       }
     },
+    onError(error) {
+      setOptimisticMessages([]);
+      toast.error(getStreamErrorMessage(error));
+    },
     onFinish(state) {
       listeners.current.onFinish?.(state.values);
       void queryClient.invalidateQueries({ queryKey: ["threads", "search"] });