feat(browser): gate vision on visualModel setting

Vision (screenshot analysis + coordinate-based interactions) is now
disabled by default. Set visualModel in browser_agent customConfig
to enable it, e.g. visualModel: 'gemini-2.5-computer-use-preview-10-2025'.

packages/core/src/agents/browser/browserAgentFactory.ts

@@ -89,52 +89,39 @@ export async function createBrowserAgentDefinition(
     (t) => !availableToolNames.includes(t),
   );
 
-  // Check if visual agent model is available for current auth type.
-  // The visual agent model (computer-use) is only available via Gemini API key
-  // or Vertex AI, not via GCA/OAuth or Cloud Shell.
-  const isVisualModelAvailable = (() => {
+  // Check whether vision can be enabled; returns undefined if all gates pass.
+  function getVisionDisabledReason(): string | undefined {
+    const browserConfig = config.getBrowserAgentConfig();
+    if (!browserConfig.customConfig.visualModel) {
+      return 'No visualModel configured.';
+    }
+    if (missingVisualTools.length > 0) {
+      return (
+        `Visual tools missing (${missingVisualTools.join(', ')}). ` +
+        `Ensure chrome-devtools-mcp is started with --experimental-vision.`
+      );
+    }
     const authType = config.getContentGeneratorConfig()?.authType;
-    if (
-      authType === AuthType.LOGIN_WITH_GOOGLE ||
-      authType === AuthType.LEGACY_CLOUD_SHELL ||
-      authType === AuthType.COMPUTE_ADC
-    ) {
-      return false;
+    const blockedAuthTypes = new Set([
+      AuthType.LOGIN_WITH_GOOGLE,
+      AuthType.LEGACY_CLOUD_SHELL,
+      AuthType.COMPUTE_ADC,
+    ]);
+    if (authType && blockedAuthTypes.has(authType)) {
+      return 'Visual agent model not available for current auth type.';
     }
-    return true;
-  })();
+    return undefined;
+  }
 
-  // Create all tools - visual delegation only if visual tools are available
   const allTools: AnyDeclarativeTool[] = [...mcpTools];
+  const visionDisabledReason = getVisionDisabledReason();
 
-  if (missingVisualTools.length > 0) {
-    debugLogger.log(
-      `Visual tools missing (${missingVisualTools.join(', ')}). ` +
-        `Visual agent delegation disabled. Ensure chrome-devtools-mcp is started with --experimental-vision.`,
-    );
-    if (printOutput) {
-      printOutput(
-        `⚠️ Visual tools unavailable - coordinate-based actions disabled.`,
-      );
-    }
-  } else if (!isVisualModelAvailable) {
-    debugLogger.log(
-      `Visual agent model not available for current auth type. ` +
-        `Visual agent delegation disabled.`,
-    );
-    if (printOutput) {
-      printOutput(
-        `⚠️ Visual agent unavailable for current auth type - coordinate-based actions disabled.`,
-      );
-    }
+  if (visionDisabledReason) {
+    debugLogger.log(`Vision disabled: ${visionDisabledReason}`);
   } else {
-    // Create visual analysis tool only if visual tools are available
-    const visualDelegationTool = createAnalyzeScreenshotTool(
-      browserManager,
-      config,
-      messageBus,
+    allTools.push(
+      createAnalyzeScreenshotTool(browserManager, config, messageBus),
     );
-    allTools.push(visualDelegationTool);
   }
 
   debugLogger.log(

packages/core/src/agents/browser/browserManager.test.ts

@@ -152,7 +152,8 @@ describe('BrowserManager', () => {
         ]),
       });
       // Persistent mode should NOT include --isolated or --autoConnect
-      const args = vi.mocked(StdioClientTransport).mock.calls[0]?.[0]?.args as string[];
+      const args = vi.mocked(StdioClientTransport).mock.calls[0]?.[0]
+        ?.args as string[];
       expect(args).not.toContain('--isolated');
       expect(args).not.toContain('--autoConnect');
     });
@@ -220,7 +221,8 @@ describe('BrowserManager', () => {
       const manager = new BrowserManager(isolatedConfig);
       await manager.ensureConnection();
 
-      const args = vi.mocked(StdioClientTransport).mock.calls[0]?.[0]?.args as string[];
+      const args = vi.mocked(StdioClientTransport).mock.calls[0]?.[0]
+        ?.args as string[];
       expect(args).toContain('--isolated');
       expect(args).not.toContain('--autoConnect');
     });
@@ -242,7 +244,8 @@ describe('BrowserManager', () => {
       const manager = new BrowserManager(existingConfig);
       await manager.ensureConnection();
 
-      const args = vi.mocked(StdioClientTransport).mock.calls[0]?.[0]?.args as string[];
+      const args = vi.mocked(StdioClientTransport).mock.calls[0]?.[0]
+        ?.args as string[];
       expect(args).toContain('--autoConnect');
       expect(args).not.toContain('--isolated');
     });
@@ -252,9 +255,7 @@ describe('BrowserManager', () => {
       vi.mocked(Client).mockImplementation(
         () =>
           ({
-            connect: vi
-              .fn()
-              .mockRejectedValue(new Error('Connection refused')),
+            connect: vi.fn().mockRejectedValue(new Error('Connection refused')),
             close: vi.fn().mockResolvedValue(undefined),
             listTools: vi.fn(),
             callTool: vi.fn(),