Revert "Revert "Rewrite extension management tools"" (#5273)

Signed-off-by: Angela Ning <aning@squareup.com>

ui/desktop/src/components/settings/extensions/agent-api.test.ts

@@ -313,6 +313,31 @@ describe('Agent API', () => {
         }),
       });
     });
+
+    it('should not mutate the original extension config', async () => {
+      const originalConfig: ExtensionConfig = {
+        type: 'stdio',
+        name: 'Extension Manager',
+        description: 'Test description',
+        cmd: 'python',
+        args: ['script.py'],
+      };
+
+      const mockResponse = {
+        ok: true,
+        text: vi.fn().mockResolvedValue('{"error": false}'),
+      };
+      mockFetch.mockResolvedValue(mockResponse);
+
+      const { replaceWithShims } = await import('./utils');
+      vi.mocked(replaceWithShims).mockResolvedValue('/path/to/shim');
+
+      await addToAgent(originalConfig, {}, 'test-session');
+
+      // Verify the original config was not mutated
+      expect(originalConfig.name).toBe('Extension Manager');
+      expect(originalConfig.cmd).toBe('python');
+    });
   });
 
   describe('removeFromAgent', () => {

ui/desktop/src/components/settings/extensions/agent-api.ts

@@ -156,21 +156,26 @@ export async function addToAgent(
   options: ToastServiceOptions = {},
   sessionId: string
 ): Promise<Response> {
+  // Create a copy to avoid mutating the original extension object
+  const extensionCopy: ExtensionConfig = { ...extension };
+
   try {
-    if (extension.type === 'stdio') {
-      extension.cmd = await replaceWithShims(extension.cmd);
+    if (extensionCopy.type === 'stdio') {
+      extensionCopy.cmd = await replaceWithShims(extensionCopy.cmd);
     }
 
-    extension.name = sanitizeName(extension.name);
+    extensionCopy.name = sanitizeName(extensionCopy.name);
 
-    return await extensionApiCall('/extensions/add', extension, options, sessionId);
+    return await extensionApiCall('/extensions/add', extensionCopy, options, sessionId);
   } catch (error) {
     // Check if this is a 428 error and make the message more descriptive
     if (error instanceof Error && error.message && error.message.includes('428')) {
       const enhancedError = new Error(
         'Failed to add extension. Goose Agent was still starting up. Please try again.'
       );
-      console.error(`Failed to add extension ${extension.name} to agent: ${enhancedError.message}`);
+      console.error(
+        `Failed to add extension ${extensionCopy.name} to agent: ${enhancedError.message}`
+      );
       throw enhancedError;
     }
     throw error;