fix(search): show honest empty state when mind map has no content (#18294)

internal/handler/mindmap.go

@@ -86,7 +86,7 @@ func runMindMap(ctx context.Context, config mindMapRunConfig) (mindMapNode, erro
 		sb.WriteString(delta)
 	}
 	fullText := sb.String()
-	if fullText == "" {
+	if strings.TrimSpace(fullText) == "" {
 		return mindMapNode{ID: "root", Children: []mindMapNode{}}, nil
 	}
 	return parseMindMapMarkdown(fullText), nil

internal/handler/mindmap_test.go

@@ -0,0 +1,72 @@
+//
+//  Copyright 2026 The InfiniFlow Authors. All Rights Reserved.
+//
+//  Licensed under the Apache License, Version 2.0 (the "License");
+//  you may not use this file except in compliance with the License.
+//  You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//  Unless required by applicable law or agreed to in writing, software
+//  distributed under the License is distributed on an "AS IS" BASIS,
+//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//  See the License for the specific language governing permissions and
+//  limitations under the License.
+//
+
+package handler
+
+import "testing"
+
+// The mind map contract: when there is nothing to map, the backend returns an
+// honest empty tree (root with no children) and the frontend renders an empty
+// state. No synthetic nodes are fabricated.
+func TestParseMindMapMarkdownEmpty(t *testing.T) {
+	t.Run("prose without headings or list items yields an empty tree", func(t *testing.T) {
+		node := parseMindMapMarkdown("I cannot summarize this text right now.")
+		if node.ID != "root" || len(node.Children) != 0 {
+			t.Fatalf("expected root-only tree, got %+v", node)
+		}
+	})
+
+	t.Run("think-only answer yields an empty tree", func(t *testing.T) {
+		node := parseMindMapMarkdown("<think>reasoning without any outline</think>")
+		if node.ID != "root" || len(node.Children) != 0 {
+			t.Fatalf("expected root-only tree, got %+v", node)
+		}
+	})
+
+	t.Run("blank answer yields an empty tree", func(t *testing.T) {
+		node := parseMindMapMarkdown("  \n\n")
+		if node.ID != "root" || len(node.Children) != 0 {
+			t.Fatalf("expected root-only tree, got %+v", node)
+		}
+	})
+}
+
+func TestParseMindMapMarkdownTree(t *testing.T) {
+	t.Run("headings and nested lists build a real tree", func(t *testing.T) {
+		node := parseMindMapMarkdown("# Title\n## Section A\n- point 1\n  - point 1.1\n## Section B\n")
+		if node.ID != "Title" {
+			t.Fatalf("expected single top heading as root, got %+v", node)
+		}
+		if len(node.Children) != 2 {
+			t.Fatalf("expected 2 sections, got %+v", node.Children)
+		}
+		sectionA := node.Children[0]
+		if sectionA.ID != "Section A" || len(sectionA.Children) != 1 {
+			t.Fatalf("unexpected Section A: %+v", sectionA)
+		}
+		point := sectionA.Children[0]
+		if point.ID != "point 1" || len(point.Children) != 1 || point.Children[0].ID != "point 1.1" {
+			t.Fatalf("unexpected nested list parse: %+v", point)
+		}
+	})
+
+	t.Run("multiple top headings keep an explicit root with children", func(t *testing.T) {
+		node := parseMindMapMarkdown("# Alpha\n# Beta\n")
+		if node.ID != "root" || len(node.Children) != 2 {
+			t.Fatalf("expected root with 2 children, got %+v", node)
+		}
+	})
+}

web/src/pages/next-search/mindmap-sheet.tsx

@@ -34,6 +34,10 @@ interface IProps extends IModalProps<any> {
 const MindMapSheet = ({ data, hideModal, loading, visible }: IProps) => {
   const { t } = useTranslation();
   const percent = usePendingMindMap();
+  // An empty tree (no children) means the backend honestly found nothing to
+  // map. Render an explicit empty state instead of a ghost "root" node.
+  const isEmptyMindMap =
+    !data || !Array.isArray(data.children) || data.children.length === 0;
   return (
     <Sheet open={visible} modal={false}>
       <SheetContent
@@ -61,7 +65,14 @@ const MindMapSheet = ({ data, hideModal, loading, visible }: IProps) => {
               <Progress value={percent} className="h-1 flex-1 min-w-10" />
             </div>
           )}
-          {!loading && (
+          {!loading && isEmptyMindMap && (
+            <div className="bg-bg-card rounded-lg w-full h-full flex items-center justify-center">
+              <p className="text-text-secondary">
+                {t('knowledgeDetails.noStructureMindmap')}
+              </p>
+            </div>
+          )}
+          {!loading && !isEmptyMindMap && (
             <div className="bg-bg-card rounded-lg w-full h-full">
               <IndentedTree data={data}></IndentedTree>
             </div>