refactor: 架构变更：Webview → VSCode 内置 Diff + 浮动标签

src/render/diffViewer.ts

@@ -0,0 +1,122 @@
+/**
+ * Diff 查看器 - 调用 VSCode 内置 Diff 编辑器
+ *
+ * 使用 vscode.diff 命令展示原始内容 vs 变更后内容，
+ * 完全不使用自定义 Webview，保持 VSCode 原生交互体验。
+ */
+
+import * as vscode from 'vscode';
+import * as path from 'path';
+import { EditRecord, FileChange } from '../models/types';
+import { ChangeSetManager } from '../snapshot/snapshotManager';
+
+export class DiffViewer {
+  constructor(private changeSetManager: ChangeSetManager) {}
+
+  /**
+   * 打开单次编辑的 Diff（VSCode 内置 Diff 编辑器）
+   */
+  async showEditDiff(editRecord: EditRecord): Promise<void> {
+    const beforeDoc = await vscode.workspace.openTextDocument({
+      content: editRecord.beforeContent,
+      language: this.getLanguageId(editRecord.filePath),
+    });
+    const afterDoc = await vscode.workspace.openTextDocument({
+      content: editRecord.afterContent,
+      language: this.getLanguageId(editRecord.filePath),
+    });
+
+    const fileName = path.basename(editRecord.filePath);
+    const toolLabel = editRecord.toolName === 'Write' ? '写入' : '编辑';
+
+    await vscode.commands.executeCommand(
+      'vscode.diff',
+      beforeDoc.uri,
+      afterDoc.uri,
+      `${fileName} — AI ${toolLabel} #${editRecord.id.slice(0, 6)} (原始 ↔ 变更后)`
+    );
+  }
+
+  /**
+   * 打开整个文件的聚合 Diff
+   */
+  async showFileDiff(fileChange: FileChange): Promise<void> {
+    const beforeDoc = await vscode.workspace.openTextDocument({
+      content: fileChange.originalContent,
+      language: this.getLanguageId(fileChange.filePath),
+    });
+    const afterDoc = await vscode.workspace.openTextDocument({
+      content: fileChange.latestContent,
+      language: this.getLanguageId(fileChange.filePath),
+    });
+
+    const fileName = path.basename(fileChange.filePath);
+
+    await vscode.commands.executeCommand(
+      'vscode.diff',
+      beforeDoc.uri,
+      afterDoc.uri,
+      `${fileName} — 原始 ↔ 变更后 (${fileChange.edits.length} 次编辑)`
+    );
+  }
+
+  /**
+   * 打开当前活动文件在编辑器中的 Diff
+   */
+  async showCurrentFileDiff(): Promise<void> {
+    const changeSet = this.changeSetManager.getCurrentSet();
+    if (!changeSet) return;
+
+    const editor = vscode.window.activeTextEditor;
+    if (!editor) return;
+
+    const normalizedPath = path.normalize(editor.document.uri.fsPath).replace(/\\/g, '/');
+    const fileChange = changeSet.changes.find(
+      c => path.normalize(c.filePath).replace(/\\/g, '/') === normalizedPath && c.status === 'pending'
+    );
+    if (!fileChange) {
+      vscode.window.showInformationMessage('AI Diff: 当前文件无待处理变更');
+      return;
+    }
+
+    await this.showFileDiff(fileChange);
+  }
+
+  /**
+   * 聚焦文件到编辑器（跳转到该文件并定位到第一个变更行）
+   */
+  async focusFileInEditor(fileChange: FileChange): Promise<void> {
+    const uri = vscode.Uri.file(fileChange.filePath);
+    const doc = await vscode.workspace.openTextDocument(uri);
+    const editor = await vscode.window.showTextDocument(doc, { preview: false });
+
+    // 滚动到第一个变更行
+    if (fileChange.diffLines.length > 0) {
+      const firstChange = fileChange.diffLines.find(
+        d => d.type === 'add' || d.type === 'delete'
+      );
+      if (firstChange) {
+        const line = (firstChange.newLineNum || firstChange.oldLineNum) - 1;
+        const pos = new vscode.Position(Math.max(0, line), 0);
+        editor.selection = new vscode.Selection(pos, pos);
+        editor.revealRange(new vscode.Range(pos, pos), vscode.TextEditorRevealType.InCenter);
+      }
+    }
+  }
+
+  private getLanguageId(filePath: string): string {
+    const ext = path.extname(filePath).toLowerCase();
+    const map: Record<string, string> = {
+      '.ts': 'typescript', '.tsx': 'typescriptreact',
+      '.js': 'javascript', '.jsx': 'javascriptreact',
+      '.json': 'json', '.md': 'markdown',
+      '.css': 'css', '.scss': 'scss', '.less': 'less',
+      '.html': 'html', '.htm': 'html',
+      '.py': 'python', '.rs': 'rust', '.go': 'go',
+      '.java': 'java', '.cpp': 'cpp', '.c': 'c',
+      '.yaml': 'yaml', '.yml': 'yaml',
+      '.xml': 'xml', '.sql': 'sql', '.sh': 'shell',
+    };
+    return map[ext] || 'plaintext';
+  }
+}