diff --git a/apps/ai-game-creator-shell/src/features/project-workspace/DesignWorkspacePanel.tsx b/apps/ai-game-creator-shell/src/features/project-workspace/DesignWorkspacePanel.tsx
index 55c470eb9..9f4c6b770 100644
--- a/apps/ai-game-creator-shell/src/features/project-workspace/DesignWorkspacePanel.tsx
+++ b/apps/ai-game-creator-shell/src/features/project-workspace/DesignWorkspacePanel.tsx
@@ -1,4 +1,12 @@
-import { ArrowLeft, Check, File, Folder, RefreshCw } from 'lucide-react';
+import {
+  ArrowLeft,
+  Check,
+  ChevronDown,
+  ChevronRight,
+  File,
+  Folder,
+  RefreshCw,
+} from 'lucide-react';
 import { useCallback, useEffect, useMemo, useState } from 'react';
 
 import { resolveTauriInvoke } from '../../app/tauri';
@@ -21,8 +29,143 @@ function phaseLabel(phase: string) {
   return PHASES.find(([id]) => id === phase)?.[1] ?? phase;
 }
 
-function pathDepth(path: string) {
-  return path.split(/[\\/]/u).filter(Boolean).length - 1;
+type DesignTreeNode = {
+  name: string;
+  path: string;
+  kind: 'directory' | 'file';
+  children: DesignTreeNode[];
+};
+
+function buildDesignTree(entries: DesignWorkspaceEntry[]) {
+  const root: DesignTreeNode = {
+    name: '工作区',
+    path: '',
+    kind: 'directory',
+    children: [],
+  };
+  const nodes = new Map<string, DesignTreeNode>([['', root]]);
+
+  for (const entry of entries) {
+    const parts = entry.path.split(/[\\/]/u).filter(Boolean);
+    let parent = root;
+    let currentPath = '';
+    parts.forEach((part, index) => {
+      currentPath = currentPath ? `${currentPath}/${part}` : part;
+      let node = nodes.get(currentPath);
+      if (!node) {
+        node = {
+          name: part,
+          path: currentPath,
+          kind:
+            index === parts.length - 1 && entry.kind !== 'directory'
+              ? 'file'
+              : 'directory',
+          children: [],
+        };
+        nodes.set(currentPath, node);
+        parent.children.push(node);
+      }
+      if (index === parts.length - 1) {
+        node.kind = entry.kind === 'directory' ? 'directory' : 'file';
+      }
+      parent = node;
+    });
+  }
+
+  function sort(nodesToSort: DesignTreeNode[]) {
+    nodesToSort.sort((left, right) => {
+      if (left.kind !== right.kind) {
+        return left.kind === 'directory' ? -1 : 1;
+      }
+      return left.name.localeCompare(right.name, 'zh-CN');
+    });
+    nodesToSort.forEach((node) => sort(node.children));
+  }
+  sort(root.children);
+  return root;
+}
+
+function DesignTreeBranch({
+  node,
+  depth,
+  expandedPaths,
+  selectedPath,
+  onToggle,
+  onOpenFile,
+}: {
+  node: DesignTreeNode;
+  depth: number;
+  expandedPaths: Set<string>;
+  selectedPath: string | null;
+  onToggle: (path: string) => void;
+  onOpenFile: (path: string) => void;
+}) {
+  const isDirectory = node.kind === 'directory';
+  const expanded = isDirectory && expandedPaths.has(node.path);
+  const paddingLeft = `${12 + depth * 14}px`;
+  const label = (
+    <>
+      {isDirectory ? (
+        expanded ? (
+          <ChevronDown size={14} aria-hidden="true" />
+        ) : (
+          <ChevronRight size={14} aria-hidden="true" />
+        )
+      ) : (
+        <span
+          className="design-workspace-tree__branch-spacer"
+          aria-hidden="true"
+        />
+      )}
+      {isDirectory ? (
+        <Folder size={15} aria-hidden="true" />
+      ) : (
+        <File size={15} aria-hidden="true" />
+      )}
+      <span title={node.path}>{node.name}</span>
+    </>
+  );
+
+  return (
+    <>
+      {isDirectory ? (
+        <button
+          type="button"
+          className="design-workspace-tree__entry is-directory"
+          style={{ paddingLeft }}
+          aria-expanded={expanded}
+          onClick={() => onToggle(node.path)}
+        >
+          {label}
+        </button>
+      ) : (
+        <button
+          type="button"
+          className={`design-workspace-tree__entry${
+            selectedPath === node.path ? ' is-selected' : ''
+          }`}
+          style={{ paddingLeft }}
+          title={node.path}
+          onClick={() => void onOpenFile(node.path)}
+        >
+          {label}
+        </button>
+      )}
+      {isDirectory && expanded
+        ? node.children.map((child) => (
+            <DesignTreeBranch
+              key={child.path}
+              node={child}
+              depth={depth + 1}
+              expandedPaths={expandedPaths}
+              selectedPath={selectedPath}
+              onToggle={onToggle}
+              onOpenFile={onOpenFile}
+            />
+          ))
+        : null}
+    </>
+  );
 }
 
 export function DesignWorkspacePanel({
@@ -35,6 +178,9 @@ export function DesignWorkspacePanel({
   const [loading, setLoading] = useState(true);
   const [previewLoading, setPreviewLoading] = useState(false);
   const [error, setError] = useState('');
+  const [expandedPaths, setExpandedPaths] = useState<Set<string>>(
+    () => new Set(),
+  );
 
   const loadWorkspace = useCallback(async () => {
     const invoke = resolveTauriInvoke();
@@ -55,6 +201,21 @@ export function DesignWorkspacePanel({
       ]);
       setView(nextView);
       setFiles(nextFiles);
+      setExpandedPaths((current) => {
+        const next = new Set(current);
+        if (current.size === 0) {
+          nextFiles
+            .filter((entry) => entry.kind === 'directory')
+            .forEach((entry) => next.add(entry.path));
+        } else {
+          nextFiles
+            .filter(
+              (entry) => entry.kind === 'directory' && next.has(entry.path),
+            )
+            .forEach((entry) => next.add(entry.path));
+        }
+        return next;
+      });
       setSelectedPath((current) =>
         current &&
         nextFiles.some(
@@ -106,16 +267,7 @@ export function DesignWorkspacePanel({
     };
   }, [loadWorkspace, projectPath]);
 
-  const sortedFiles = useMemo(
-    () =>
-      [...files].sort((left, right) => {
-        if (left.kind !== right.kind) {
-          return left.kind === 'directory' ? -1 : 1;
-        }
-        return left.path.localeCompare(right.path, 'zh-CN');
-      }),
-    [files],
-  );
+  const sortedFiles = useMemo(() => buildDesignTree(files), [files]);
 
   const openFile = useCallback(
     async (path: string) => {
@@ -210,7 +362,7 @@ export function DesignWorkspacePanel({
           </header>
           {loading ? (
             <p className="design-workspace-empty">正在读取工作区…</p>
-          ) : sortedFiles.length === 0 ? (
+          ) : sortedFiles.children.length === 0 ? (
             <div className="design-workspace-empty">
               <Folder size={24} aria-hidden="true" />
               <strong>工作区还没有文件</strong>
@@ -218,34 +370,24 @@ export function DesignWorkspacePanel({
             </div>
           ) : (
             <div className="design-workspace-tree__list">
-              {sortedFiles.map((entry) => {
-                const isDirectory = entry.kind === 'directory';
-                return isDirectory ? (
-                  <div
-                    key={entry.path}
-                    className="design-workspace-tree__entry is-directory"
-                    style={{
-                      paddingLeft: `${12 + pathDepth(entry.path) * 12}px`,
-                    }}
-                  >
-                    <Folder size={15} aria-hidden="true" />
-                    <span>{entry.path}</span>
-                  </div>
-                ) : (
-                  <button
-                    key={entry.path}
-                    type="button"
-                    className={`design-workspace-tree__entry${selectedPath === entry.path ? ' is-selected' : ''}`}
-                    style={{
-                      paddingLeft: `${12 + pathDepth(entry.path) * 12}px`,
-                    }}
-                    onClick={() => void openFile(entry.path)}
-                  >
-                    <File size={15} aria-hidden="true" />
-                    <span>{entry.path}</span>
-                  </button>
-                );
-              })}
+              {sortedFiles.children.map((node) => (
+                <DesignTreeBranch
+                  key={node.path}
+                  node={node}
+                  depth={0}
+                  expandedPaths={expandedPaths}
+                  selectedPath={selectedPath}
+                  onToggle={(path) =>
+                    setExpandedPaths((current) => {
+                      const next = new Set(current);
+                      if (next.has(path)) next.delete(path);
+                      else next.add(path);
+                      return next;
+                    })
+                  }
+                  onOpenFile={openFile}
+                />
+              ))}
             </div>
           )}
         </aside>
diff --git a/apps/ai-game-creator-shell/src/styles.css b/apps/ai-game-creator-shell/src/styles.css
index 9b0a4e2c1..0d6577870 100644
--- a/apps/ai-game-creator-shell/src/styles.css
+++ b/apps/ai-game-creator-shell/src/styles.css
@@ -8374,6 +8374,12 @@ iframe.preview-frame {
   white-space: nowrap;
 }
 
+.design-workspace-tree__branch-spacer {
+  display: block;
+  width: 14px;
+  flex: 0 0 14px;
+}
+
 button.design-workspace-tree__entry {
   cursor: pointer;
 }