fix: 侧边栏高亮跟随标签切换同步更新，支持显示独立打开的文件

- 添加 updateSidebarHighlight() 函数，标签切换时只更新高亮状态而非重建整棵树
- 给树节点添加 data-path 属性用于精确定位高亮
- 新增「已打开的文件」区域，显示不在当前文件夹内的独立文件
- 独立文件支持点击切换、修改状态标识、活跃高亮
- 无文件夹打开时自动显示独立文件列表，全部关闭后隐藏侧边栏

renderer/renderer.js

@@ -539,6 +539,36 @@
     }
   }
 
+  // ===== Sidebar Highlight =====
+  // Update sidebar active highlight without re-rendering the entire tree
+  function updateSidebarHighlight() {
+    const tab = getActiveTab();
+    const activePath = tab ? tab.filePath : null;
+
+    // If no folder is open, just re-render independent files
+    if (!currentRootPath) {
+      sidebarTree.innerHTML = '';
+      const indepSection = renderIndependentFiles();
+      if (indepSection) sidebarTree.appendChild(indepSection);
+      return;
+    }
+
+    // Re-render independent files section (files may have been added/removed)
+    const oldSection = sidebarTree.querySelector('.independent-files-section');
+    const newSection = renderIndependentFiles();
+    if (oldSection) oldSection.remove();
+    if (newSection) sidebarTree.insertBefore(newSection, sidebarTree.firstChild);
+
+    // Update folder tree items
+    const treeItems = sidebarTree.querySelectorAll('.tree-item:not(.independent-file-item)');
+    treeItems.forEach(item => {
+      const itemPath = item.dataset.path;
+      if (itemPath) {
+        item.classList.toggle('active', itemPath === activePath);
+      }
+    });
+  }
+
   // ===== Tab Operations =====
   function getActiveTab() {
     return tabs.find(t => t.id === activeTabId) || null;
@@ -589,6 +619,15 @@
     // Update modified state
     setModified(tab.isModified);
 
+    // Update sidebar highlight and independent files
+    updateSidebarHighlight();
+    // If no folder is open but we have open files, ensure sidebar is visible
+    if (!currentRootPath && tabs.length > 0) {
+      sidebar.classList.remove('collapsed');
+    } else if (!currentRootPath && tabs.length === 0) {
+      sidebar.classList.add('collapsed');
+    }
+
     // Notify main process about active file
     if (typeof window.electronAPI !== 'undefined') {
       window.electronAPI.tabSwitched(tab.filePath);
@@ -638,6 +677,7 @@
     loadTabState(tab);
     renderTabBar();
     updateTitle();
+    updateSidebarHighlight();
     welcomeScreen.classList.add('hidden');
   }
 
@@ -684,6 +724,7 @@
 
     renderTabBar();
     updateTitle();
+    updateSidebarHighlight();
   }
 
   // ===== File Size Limit =====
@@ -1379,6 +1420,7 @@
       if (tab && tab.filePath === node.path) {
         item.classList.add('active');
       }
+      item.dataset.path = node.path;
 
       parent.appendChild(item);
 
@@ -1407,11 +1449,78 @@
     return lastTreeData || [];
   }
 
-  // Override renderTree to cache data
+  // Build list of open files that are NOT inside currentRootPath
+  function getIndependentFiles() {
+    if (!tabs.length) return [];
+    return tabs.filter(t => {
+      if (!t.filePath) return false; // skip unnamed tabs
+      if (!currentRootPath) return true; // no folder open → all files are "independent"
+      // Check if file is inside the current root path
+      return !t.filePath.startsWith(currentRootPath);
+    });
+  }
+
+  function renderIndependentFiles() {
+    const files = getIndependentFiles();
+    if (files.length === 0) return null;
+
+    const section = document.createElement('div');
+    section.className = 'independent-files-section';
+
+    const header = document.createElement('div');
+    header.className = 'independent-files-header';
+    header.textContent = '已打开的文件';
+    section.appendChild(header);
+
+    for (const tab of files) {
+      const item = document.createElement('div');
+      item.className = 'tree-item independent-file-item';
+      item.style.paddingLeft = '8px';
+      item.dataset.path = tab.filePath;
+
+      const icon = document.createElement('span');
+      icon.className = 'tree-icon';
+      icon.innerHTML = '<svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2"><path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"></path><polyline points="14 2 14 8 20 8"></polyline></svg>';
+      item.appendChild(icon);
+
+      const name = document.createElement('span');
+      name.className = 'tree-name';
+      name.textContent = getFileName(tab.filePath);
+      item.appendChild(name);
+
+      // Mark as modified
+      if (tab.isModified) {
+        const dot = document.createElement('span');
+        dot.className = 'independent-modified-dot';
+        dot.textContent = ' •';
+        item.appendChild(dot);
+      }
+
+      // Highlight if active
+      if (tab.id === activeTabId) {
+        item.classList.add('active');
+      }
+
+      item.addEventListener('click', (e) => {
+        e.stopPropagation();
+        switchToTab(tab.id);
+      });
+
+      section.appendChild(item);
+    }
+    return section;
+  }
+
+  // Override renderTree to cache data and prepend independent files
   const _originalRenderTree = renderTree;
   renderTree = function(tree, rootPath) {
     lastTreeData = tree;
     _originalRenderTree(tree, rootPath);
+    // Prepend independent files section
+    const indepSection = renderIndependentFiles();
+    if (indepSection) {
+      sidebarTree.insertBefore(indepSection, sidebarTree.firstChild);
+    }
   };
 
   // ===== Search Bar Init =====

renderer/style.css

@@ -860,6 +860,28 @@ html, body {
   text-overflow: ellipsis;
 }
 
+/* ===== Independent Files Section ===== */
+.independent-files-section {
+  border-bottom: 1px solid var(--border);
+  margin-bottom: 4px;
+  padding-bottom: 4px;
+}
+
+.independent-files-header {
+  font-size: 11px;
+  font-weight: 600;
+  color: var(--text-tertiary);
+  text-transform: uppercase;
+  letter-spacing: 0.5px;
+  padding: 8px 12px 4px 12px;
+}
+
+.independent-file-item .independent-modified-dot {
+  color: var(--primary);
+  font-size: 14px;
+  margin-left: 4px;
+}
+
 /* ===== Search & Replace Bar ===== */
 #search-bar {
   background: var(--search-bg);