test(web-search): add tests for country and language parameters

Added three new test cases to verify the new country, search_lang, and ui_lang
parameters are correctly passed to the Brave Search API.

Co-Authored-By: Claude <noreply@anthropic.com>

src/agents/tools/web-tools.enabled-defaults.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, it } from "vitest";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 import { createWebFetchTool, createWebSearchTool } from "./web-tools.js";
 
@@ -21,3 +21,71 @@ describe("web tools defaults", () => {
     expect(tool?.name).toBe("web_search");
   });
 });
+
+describe("web_search country and language parameters", () => {
+  const priorFetch = global.fetch;
+
+  beforeEach(() => {
+    vi.stubEnv("BRAVE_API_KEY", "test-key");
+  });
+
+  afterEach(() => {
+    vi.unstubAllEnvs();
+    // @ts-expect-error global fetch cleanup
+    global.fetch = priorFetch;
+  });
+
+  it("should pass country parameter to Brave API", async () => {
+    const mockFetch = vi.fn(() =>
+      Promise.resolve({
+        ok: true,
+        json: () => Promise.resolve({ web: { results: [] } }),
+      } as Response),
+    );
+    // @ts-expect-error mock fetch
+    global.fetch = mockFetch;
+
+    const tool = createWebSearchTool({ config: undefined, sandboxed: true });
+    expect(tool).not.toBeNull();
+
+    await tool?.execute?.(1, { query: "test", country: "DE" });
+
+    expect(mockFetch).toHaveBeenCalled();
+    const url = new URL(mockFetch.mock.calls[0][0] as string);
+    expect(url.searchParams.get("country")).toBe("DE");
+  });
+
+  it("should pass search_lang parameter to Brave API", async () => {
+    const mockFetch = vi.fn(() =>
+      Promise.resolve({
+        ok: true,
+        json: () => Promise.resolve({ web: { results: [] } }),
+      } as Response),
+    );
+    // @ts-expect-error mock fetch
+    global.fetch = mockFetch;
+
+    const tool = createWebSearchTool({ config: undefined, sandboxed: true });
+    await tool?.execute?.(1, { query: "test", search_lang: "de" });
+
+    const url = new URL(mockFetch.mock.calls[0][0] as string);
+    expect(url.searchParams.get("search_lang")).toBe("de");
+  });
+
+  it("should pass ui_lang parameter to Brave API", async () => {
+    const mockFetch = vi.fn(() =>
+      Promise.resolve({
+        ok: true,
+        json: () => Promise.resolve({ web: { results: [] } }),
+      } as Response),
+    );
+    // @ts-expect-error mock fetch
+    global.fetch = mockFetch;
+
+    const tool = createWebSearchTool({ config: undefined, sandboxed: true });
+    await tool?.execute?.(1, { query: "test", ui_lang: "de" });
+
+    const url = new URL(mockFetch.mock.calls[0][0] as string);
+    expect(url.searchParams.get("ui_lang")).toBe("de");
+  });
+});