feat(FN-3758): align web fetch test coverage and documentation

Aligns web fetch tool test coverage across multiple test suites and updates the agents documentation, with a patch changeset for `@runfusion/fusion`.

Fusion-Task-Id: FN-3758

packages/cli/src/__tests__/extension-web-fetch.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, it, vi } from "vitest";
+
+const fetchWebContentMock = vi.hoisted(() => vi.fn());
+
+vi.mock("@fusion/engine", () => ({
+  fetchWebContent: fetchWebContentMock,
+}));
+
+import kbExtension from "../extension.js";
+
+describe("extension fn_web_fetch", () => {
+  it("registers and executes fn_web_fetch", async () => {
+    const tools = new Map<string, any>();
+    const api = {
+      registerTool(def: any) {
+        tools.set(def.name, def);
+      },
+      registerCommand: vi.fn(),
+      registerShortcut: vi.fn(),
+      registerFlag: vi.fn(),
+      on: vi.fn(),
+    } as any;
+
+    fetchWebContentMock.mockResolvedValue({
+      finalUrl: "https://example.com/final",
+      status: 200,
+      contentType: "text/plain",
+      title: "Example",
+      content: "hello world",
+      truncated: false,
+      bytesRead: 11,
+    });
+
+    kbExtension(api);
+    const tool = tools.get("fn_web_fetch");
+    expect(tool).toBeTruthy();
+
+    const result = await tool.execute("id", { url: "https://example.com" }, undefined, undefined, { cwd: process.cwd() });
+    expect(fetchWebContentMock).toHaveBeenCalledWith("https://example.com", { timeoutMs: undefined, maxBytes: undefined });
+    expect(result.content[0].text).toContain("https://example.com/final");
+    expect(result.details.status).toBe(200);
+  });
+});