feat(browser): add maxActionsPerTask for browser agent setting (#23216)

packages/cli/src/config/settingsSchema.ts

@@ -1208,6 +1208,16 @@ const SETTINGS_SCHEMA = {
               'Disable user input on browser window during automation.',
             showInDialog: false,
           },
+          maxActionsPerTask: {
+            type: 'number',
+            label: 'Max Actions Per Task',
+            category: 'Advanced',
+            requiresRestart: false,
+            default: 100,
+            description:
+              'The maximum number of tool calls allowed per browser task. Enforcement is hard: the agent will be terminated when the limit is reached.',
+            showInDialog: false,
+          },
           confirmSensitiveActions: {
             type: 'boolean',
             label: 'Confirm Sensitive Actions',

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

@@ -112,6 +112,7 @@ Some errors are unrecoverable and retrying will never help. When you see ANY of
 - "Could not connect to Chrome" or "Failed to connect to Chrome" or "Timed out connecting to Chrome" — Include the full error message with its remediation steps in your summary verbatim. Do NOT paraphrase or omit instructions.
 - "Browser closed" or "Target closed" or "Session closed" — The browser process has terminated. Include the error and tell the user to try again.
 - "net::ERR_" network errors on the SAME URL after 2 retries — the site is unreachable. Report the URL and error.
+- "reached maximum action limit" — You have performed too many actions in this task. Stop immediately and report this limit to the user.
 - Any error that appears IDENTICALLY 3+ times in a row — it will not resolve by retrying.
 Do NOT keep retrying terminal errors. Report them with actionable remediation steps and exit immediately.
 

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

@@ -697,4 +697,28 @@ describe('BrowserManager', () => {
       expect(injectAutomationOverlay).not.toHaveBeenCalled();
     });
   });
+
+  describe('Rate limiting', () => {
+    it('should terminate task when maxActionsPerTask is reached', async () => {
+      const limitedConfig = makeFakeConfig({
+        agents: {
+          browser: {
+            maxActionsPerTask: 3,
+          },
+        },
+      });
+      const manager = new BrowserManager(limitedConfig);
+
+      // First 3 calls should succeed
+      await manager.callTool('take_snapshot', {});
+      await manager.callTool('take_snapshot', { some: 'args' });
+      await manager.callTool('take_snapshot', { other: 'args' });
+      await manager.callTool('take_snapshot', { other: 'new args' });
+
+      // 4th call should throw
+      await expect(manager.callTool('take_snapshot', {})).rejects.toThrow(
+        /maximum action limit \(3\)/,
+      );
+    });
+  });
 });

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

@@ -97,6 +97,10 @@ export class BrowserManager {
   private mcpTransport: StdioClientTransport | undefined;
   private discoveredTools: McpTool[] = [];
 
+  /** State for action rate limiting */
+  private actionCounter = 0;
+  private readonly maxActionsPerTask: number;
+
   /**
    * Whether to inject the automation overlay.
    * Always false in headless mode (no visible window to decorate).
@@ -108,6 +112,8 @@ export class BrowserManager {
     const browserConfig = config.getBrowserAgentConfig();
     this.shouldInjectOverlay = !browserConfig?.customConfig?.headless;
     this.shouldDisableInput = config.shouldDisableBrowserUserInput();
+    this.maxActionsPerTask =
+      browserConfig?.customConfig.maxActionsPerTask ?? 100;
   }
 
   /**
@@ -151,6 +157,16 @@ export class BrowserManager {
       throw signal.reason ?? new Error('Operation cancelled');
     }
 
+    // Hard enforcement of per-action rate limit
+    if (this.actionCounter > this.maxActionsPerTask) {
+      const error = new Error(
+        `Browser agent reached maximum action limit (${this.maxActionsPerTask}). ` +
+          `Task terminated to prevent runaway execution. To config the limit, use maxActionsPerTask in the settings.`,
+      );
+      throw error;
+    }
+    this.actionCounter++;
+
     const errorMessage = this.checkNavigationRestrictions(toolName, args);
     if (errorMessage) {
       return {

packages/core/src/config/config.test.ts

@@ -1474,6 +1474,22 @@ describe('Server Config (config.ts)', () => {
       expect(browserConfig.customConfig.visualModel).toBe(
         'custom-visual-model',
       );
+      expect(browserConfig.customConfig.maxActionsPerTask).toBe(100); // default
+    });
+
+    it('should return custom maxActionsPerTask', () => {
+      const params: ConfigParameters = {
+        ...baseParams,
+        agents: {
+          browser: {
+            maxActionsPerTask: 50,
+          },
+        },
+      };
+      const config = new Config(params);
+      const browserConfig = config.getBrowserAgentConfig();
+
+      expect(browserConfig.customConfig.maxActionsPerTask).toBe(50);
     });
 
     it('should apply defaults for partial custom config', () => {

packages/core/src/config/config.ts

@@ -331,6 +331,8 @@ export interface BrowserAgentCustomConfig {
   allowedDomains?: string[];
   /** Disable user input on the browser window during automation. Default: true in non-headless mode */
   disableUserInput?: boolean;
+  /** Maximum number of actions (tool calls) allowed per task. Default: 100 */
+  maxActionsPerTask?: number;
   /** Whether to confirm sensitive actions (e.g., fill_form, evaluate_script). */
   confirmSensitiveActions?: boolean;
   /** Whether to block file uploads. */
@@ -3194,6 +3196,7 @@ export class Config implements McpContext, AgentLoopContext {
         visualModel: customConfig.visualModel,
         allowedDomains: customConfig.allowedDomains,
         disableUserInput: customConfig.disableUserInput,
+        maxActionsPerTask: customConfig.maxActionsPerTask ?? 100,
         confirmSensitiveActions: customConfig.confirmSensitiveActions,
         blockFileUploads: customConfig.blockFileUploads,
       },