feat(conflicts): respect git.mergeEditor when opening conflicted files

src/panels/MainPanel.ts

@@ -1565,10 +1565,17 @@ export class MainPanel {
         case 'openConflictFile': {
           const fullPath = this.resolveRepoRelativePath(message.payload.file, 'openConflictFile');
           const fileUri = vscode.Uri.file(fullPath);
-          // Try to open in VS Code's 3-way merge editor, fallback to normal editor
-          try {
-            await vscode.commands.executeCommand('git.openMergeEditor', fileUri);
-          } catch {
+          // Follow the native git.mergeEditor preference (#67): only try the
+          // 3-way merge editor when it is enabled (the VS Code default).
+          const useMergeEditor = vscode.workspace.getConfiguration('git').get<boolean>('mergeEditor', true);
+          if (useMergeEditor) {
+            // Try to open in VS Code's 3-way merge editor, fallback to normal editor
+            try {
+              await vscode.commands.executeCommand('git.openMergeEditor', fileUri);
+            } catch {
+              await vscode.window.showTextDocument(fileUri);
+            }
+          } else {
             await vscode.window.showTextDocument(fileUri);
           }
           break;

src/panels/__tests__/MainPanel.test.ts

@@ -37,6 +37,7 @@ const H = vi.hoisted(() => {
     messageHandler: null as null | ((m: unknown) => unknown),
     panel: null as null | { webview: { postMessage: ReturnType<typeof vi.fn> } },
     repos: [] as Array<{ path: string; name: string; type: string }>,
+    configValues: {} as Record<string, unknown>,
   };
 });
 
@@ -68,9 +69,15 @@ vi.mock('vscode', () => {
       showWarningMessage: vi.fn(),
       showErrorMessage: vi.fn(async () => undefined),
       showSaveDialog: vi.fn(async () => undefined),
+      showTextDocument: vi.fn(async () => undefined),
     },
     workspace: {
-      getConfiguration: () => ({ get: (_k: string, d?: unknown) => d }),
+      getConfiguration: (section?: string) => ({
+        get: (k: string, d?: unknown) => {
+          const key = section ? `${section}.${k}` : k;
+          return key in H.configValues ? H.configValues[key] : d;
+        },
+      }),
       getWorkspaceFolder: () => ({ uri: { fsPath: '/repo' } }),
       workspaceFolders: [{ uri: { fsPath: '/repo' } }],
       onDidChangeConfiguration: () => ({ dispose() {} }),
@@ -128,6 +135,7 @@ beforeEach(() => {
   H.git.fileExistsAtRef.mockResolvedValue(true);
   H.git.getEmptyTreeRef.mockResolvedValue('4b825dc642cb6eb9a060e54bf8d69288fbee4904');
   H.repos = [{ path: '/repo', name: 'repo', type: 'root' }];
+  H.configValues = {};
   (MainPanel as unknown as { currentPanel: unknown }).currentPanel = undefined;
   MainPanel.createOrShow(extUri, '/repo');
 });
@@ -289,6 +297,53 @@ describe('MainPanel message routing', () => {
   });
 });
 
+describe('MainPanel openConflictFile honours git.mergeEditor', () => {
+  const openConflict = () => dispatch({ type: 'openConflictFile', payload: { file: 'src/conflict.ts' } });
+
+  it('opens a normal text editor (no merge editor) when git.mergeEditor is false', async () => {
+    const vscode = await import('vscode');
+    H.configValues['git.mergeEditor'] = false;
+
+    await openConflict();
+
+    expect(vscode.window.showTextDocument).toHaveBeenCalledWith(
+      expect.objectContaining({ fsPath: expect.stringContaining('conflict.ts') }),
+    );
+    expect(vscode.commands.executeCommand).not.toHaveBeenCalledWith('git.openMergeEditor', expect.anything());
+  });
+
+  it('uses the merge editor when git.mergeEditor is true', async () => {
+    const vscode = await import('vscode');
+    H.configValues['git.mergeEditor'] = true;
+
+    await openConflict();
+
+    expect(vscode.commands.executeCommand).toHaveBeenCalledWith(
+      'git.openMergeEditor',
+      expect.objectContaining({ fsPath: expect.stringContaining('conflict.ts') }),
+    );
+    expect(vscode.window.showTextDocument).not.toHaveBeenCalled();
+  });
+
+  it('defaults to the merge editor when git.mergeEditor is unset', async () => {
+    const vscode = await import('vscode');
+
+    await openConflict();
+
+    expect(vscode.commands.executeCommand).toHaveBeenCalledWith('git.openMergeEditor', expect.anything());
+    expect(vscode.window.showTextDocument).not.toHaveBeenCalled();
+  });
+
+  it('falls back to a normal editor when the merge editor command fails', async () => {
+    const vscode = await import('vscode');
+    (vscode.commands.executeCommand as ReturnType<typeof vi.fn>).mockRejectedValueOnce(new Error('merge editor unavailable'));
+
+    await openConflict();
+
+    expect(vscode.window.showTextDocument).toHaveBeenCalled();
+  });
+});
+
 describe('MainPanel error handling', () => {
   it('posts notGitRepo when git reports "not a git repository"', async () => {
     H.git.log.mockRejectedValue(new GitError('fatal: not a git repository', 128, ['log']));