[fix] Anthropic CUA triple_click mapping (#2104)

# Why

`AnthropicCUAClient.convertToolUseToAction()` handled actions like
`click`, `double_click`, and `left_click`, but did not explicitly
support `triple_click`.

Two issues:

1. The action type remained in snake_case (`triple_click`) instead of
being normalized to `tripleClick` — the format expected by
`v3CuaAgentHandler.executeAction()`.
2. Coordinates provided via Anthropic’s coordinate: [x, y] format were
not converted into the separate x / y fields required by the handler.

As a result, Anthropic triple-click actions were silently ignored by the
handler switch.

# What Changed

- AnthropicCUAClient.ts
- Added explicit handling for triple_click / tripleClick in
convertToolUseToAction()
  - Mirrors the existing double_click implementation
  - Normalizes action type to tripleClick
  - Extracts coordinates from both:
    - coordinate: [x, y]
    - direct x / y fields

- v3CuaAgentHandler.ts
  - Added "triple_click" as a switch-case alias in executeAction()

# Test Plan

Added `anthropic-cua-triple-click.test.ts` (Vitest) covering:

- triple_click with coordinate: [x, y]
- triple_click with direct x / y fields

All existing unit tests continue to pass.


<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Fix incorrect handling of Anthropic CUA `triple_click` so triple-click
actions run and coordinates are parsed correctly. Adds unit tests for
both coordinate-array and x/y formats, and a changeset for a patch
release.

- **Bug Fixes**
- Normalize `triple_click`/`tripleClick` to internal `tripleClick` in
`AnthropicCUAClient`, extracting `x`/`y` from `coordinate` or explicit
fields.
- Add `"triple_click"` case to `V3CuaAgentHandler` so both naming styles
execute consistently.

- **Dependencies**
  - Add changeset to publish a patch for `@browserbasehq/stagehand`.

<sup>Written for commit 7a54548.
Summary will update on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

---------

Co-authored-by: Claude <noreply@anthropic.com>

Author: chromiebot

.changeset/fix-anthropic-cua-triple-click.md

@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+Fix Anthropic CUA `triple_click` action mapping.

packages/core/lib/v3/agent/AnthropicCUAClient.ts

@@ -901,6 +901,17 @@ export class AnthropicCUAClient extends AgentClient {
               (input.coordinate ? (input.coordinate as number[])[1] : 0),
             ...input,
           };
+        } else if (action === "triple_click" || action === "tripleClick") {
+          return {
+            type: "tripleClick",
+            x:
+              (input.x as number) ||
+              (input.coordinate ? (input.coordinate as number[])[0] : 0),
+            y:
+              (input.y as number) ||
+              (input.coordinate ? (input.coordinate as number[])[1] : 0),
+            ...input,
+          };
         } else if (action === "scroll") {
           // Convert Anthropic's coordinate, scroll_amount and scroll_direction into scroll_x and scroll_y
           const x =

packages/core/lib/v3/handlers/v3CuaAgentHandler.ts

@@ -324,6 +324,7 @@ export class V3CuaAgentHandler {
         }
         return { success: true };
       }
+      case "triple_click":
       case "tripleClick": {
         const { x, y } = action;
         if (recording) {

packages/core/tests/unit/anthropic-cua-triple-click.test.ts

@@ -0,0 +1,99 @@
+import { describe, expect, it, vi, beforeEach } from "vitest";
+import { AnthropicCUAClient } from "../../lib/v3/agent/AnthropicCUAClient.js";
+import Anthropic from "@anthropic-ai/sdk";
+
+vi.mock("@anthropic-ai/sdk", () => {
+  const mockCreate = vi.fn();
+
+  return {
+    default: class MockAnthropic {
+      beta = {
+        messages: {
+          create: mockCreate,
+        },
+      };
+    },
+  };
+});
+
+describe("AnthropicCUAClient triple_click handling", () => {
+  let mockCreate: ReturnType<typeof vi.fn>;
+  let client: AnthropicCUAClient;
+  let executedActions: Array<Record<string, unknown>>;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    const anthropic = new Anthropic({ apiKey: "test" });
+    mockCreate = anthropic.beta.messages.create as ReturnType<typeof vi.fn>;
+
+    client = new AnthropicCUAClient("anthropic", "claude-sonnet-4-5-20250929", undefined, {
+      apiKey: "test-key",
+    });
+    client.setViewport(1280, 720);
+    client.setScreenshotProvider(async () => "fake-base64-screenshot");
+
+    executedActions = [];
+    client.setActionHandler(async (action) => {
+      executedActions.push({ ...action });
+    });
+  });
+
+  it("should convert triple_click with coordinate array to tripleClick action", async () => {
+    mockCreate.mockResolvedValue({
+      id: "test-id",
+      content: [
+        {
+          type: "tool_use",
+          id: "tool-1",
+          name: "computer",
+          input: {
+            action: "triple_click",
+            coordinate: [640, 360],
+          },
+        },
+      ],
+      usage: { input_tokens: 10, output_tokens: 20 },
+    });
+
+    const logger = vi.fn();
+    await client.executeStep(
+      [{ role: "user", content: "triple click the paragraph" }],
+      logger,
+    );
+
+    expect(executedActions).toHaveLength(1);
+    expect(executedActions[0].type).toBe("tripleClick");
+    expect(executedActions[0].x).toBe(640);
+    expect(executedActions[0].y).toBe(360);
+  });
+
+  it("should convert triple_click with x/y fields to tripleClick action", async () => {
+    mockCreate.mockResolvedValue({
+      id: "test-id",
+      content: [
+        {
+          type: "tool_use",
+          id: "tool-2",
+          name: "computer",
+          input: {
+            action: "triple_click",
+            x: 100,
+            y: 200,
+          },
+        },
+      ],
+      usage: { input_tokens: 10, output_tokens: 20 },
+    });
+
+    const logger = vi.fn();
+    await client.executeStep(
+      [{ role: "user", content: "triple click the line" }],
+      logger,
+    );
+
+    expect(executedActions).toHaveLength(1);
+    expect(executedActions[0].type).toBe("tripleClick");
+    expect(executedActions[0].x).toBe(100);
+    expect(executedActions[0].y).toBe(200);
+  });
+});