feat(vscode-ide-companion): 更新核心服务和扩展功能

- 增强 extension.ts，集成新增功能
- 优化 ide-server.ts，改进服务端逻辑
- 更新 diff-manager.ts，提升差异管理能力
- 改进 ACP 连接和消息处理
- 更新会话处理器，支持新的交互模式

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/vscode-ide-companion/src/diff-manager.ts

@@ -76,15 +76,26 @@ export class DiffManager {
 
   /**
    * Creates and shows a new diff view.
+   * @param filePath Path to the file being diffed
+   * @param oldContent The original content (left side)
+   * @param newContent The modified content (right side)
    */
-  async showDiff(filePath: string, newContent: string) {
-    const fileUri = vscode.Uri.file(filePath);
+  async showDiff(filePath: string, oldContent: string, newContent: string) {
+    const _fileUri = vscode.Uri.file(filePath);
 
+    // Left side: old content using qwen-diff scheme
+    const leftDocUri = vscode.Uri.from({
+      scheme: DIFF_SCHEME,
+      path: filePath,
+      query: `old&rand=${Math.random()}`,
+    });
+    this.diffContentProvider.setContent(leftDocUri, oldContent);
+
+    // Right side: new content using qwen-diff scheme
     const rightDocUri = vscode.Uri.from({
       scheme: DIFF_SCHEME,
       path: filePath,
-      // cache busting
-      query: `rand=${Math.random()}`,
+      query: `new&rand=${Math.random()}`,
     });
     this.diffContentProvider.setContent(rightDocUri, newContent);
 
@@ -94,26 +105,13 @@ export class DiffManager {
       rightDocUri,
     });
 
-    const diffTitle = `${path.basename(filePath)} ↔ Modified`;
+    const diffTitle = `${path.basename(filePath)} (Before ↔ After)`;
     await vscode.commands.executeCommand(
       'setContext',
       'qwen.diff.isVisible',
       true,
     );
 
-    let leftDocUri;
-    try {
-      await vscode.workspace.fs.stat(fileUri);
-      leftDocUri = fileUri;
-    } catch {
-      // We need to provide an empty document to diff against.
-      // Using the 'untitled' scheme is one way to do this.
-      leftDocUri = vscode.Uri.from({
-        scheme: 'untitled',
-        path: filePath,
-      });
-    }
-
     await vscode.commands.executeCommand(
       'vscode.diff',
       leftDocUri,