Add Haiku 4.5 computer use support (#1137)

# why
New model dropped

# what changed
Added support for haiku 4.5

# test plan

Author: miguelg719

.changeset/gentle-beds-enjoy.md

@@ -0,0 +1,5 @@
+---
+"@browserbasehq/stagehand": patch
+---
+
+Add haiku 4.5 computer use support

evals/deterministic/tests/Errors/apiKeyError.test.ts

@@ -24,9 +24,10 @@ test.describe("API key/LLMClient error", () => {
     }
 
     expect(errorThrown).toBeInstanceOf(Error);
-    expect(errorThrown?.message).toContain(
-      "No LLM API key or LLM Client configured",
-    );
+    expect(
+      errorThrown?.message?.includes("No LLM API key or LLM Client configured") ||
+      errorThrown?.message?.includes("API key is missing. Pass it using the 'apiKey' parameter")
+    ).toBe(true);
 
     await stagehand.close();
   });
@@ -47,9 +48,10 @@ test.describe("API key/LLMClient error", () => {
     }
 
     expect(errorThrown).toBeInstanceOf(Error);
-    expect(errorThrown?.message).toContain(
-      "No LLM API key or LLM Client configured",
-    );
+    expect(
+      errorThrown?.message?.includes("No LLM API key or LLM Client configured") ||
+      errorThrown?.message?.includes("API key is missing. Pass it using the 'apiKey' parameter")
+    ).toBe(true);
 
     await stagehand.close();
   });
@@ -68,9 +70,10 @@ test.describe("API key/LLMClient error", () => {
     }
 
     expect(errorThrown).toBeInstanceOf(Error);
-    expect(errorThrown?.message).toContain(
-      "No LLM API key or LLM Client configured",
-    );
+    expect(
+      errorThrown?.message?.includes("No LLM API key or LLM Client configured") ||
+      errorThrown?.message?.includes("API key is missing. Pass it using the 'apiKey' parameter")
+    ).toBe(true);
 
     await stagehand.close();
   });

lib/agent/AgentProvider.ts

@@ -15,6 +15,7 @@ export const modelToAgentProviderMap: Record<string, AgentType> = {
   "computer-use-preview": "openai",
   "computer-use-preview-2025-03-11": "openai",
   "claude-3-7-sonnet-latest": "anthropic",
+  "claude-haiku-4-5-20251001": "anthropic",
   "claude-sonnet-4-20250514": "anthropic",
   "claude-sonnet-4-5-20250929": "anthropic",
   "gemini-2.5-computer-use-preview-10-2025": "google",

stagehand.config.ts

@@ -7,7 +7,7 @@ const StagehandConfig: ConstructorParams = {
   domSettleTimeoutMs: 30_000 /* Timeout for DOM to settle in milliseconds */,
 
   //   LLM configuration
-  modelName: "gpt-4o" /* Name of the model to use */,
+  modelName: "openai/gpt-4.1-mini" /* Name of the model to use */,
   modelClientOptions: {
     apiKey: process.env.OPENAI_API_KEY,
   } /* Configuration options for the model client */,