fix: unify web tool proxy path (#27430) (thanks @kevinWangSheng)

src/agents/tools/web-tools.fetch.test.ts

@@ -1,3 +1,4 @@
+import { EnvHttpProxyAgent } from "undici";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import * as ssrf from "../../infra/net/ssrf.js";
 import { withFetchPreconnect } from "../../test-utils/fetch-mock.js";
@@ -146,6 +147,7 @@ describe("web_fetch extraction fallbacks", () => {
 
   afterEach(() => {
     global.fetch = priorFetch;
+    vi.unstubAllEnvs();
     vi.restoreAllMocks();
   });
 
@@ -256,6 +258,27 @@ describe("web_fetch extraction fallbacks", () => {
     expect(details?.warning).toContain("Response body truncated");
   });
 
+  it("uses proxy-aware dispatcher when HTTP_PROXY is configured", async () => {
+    vi.stubEnv("HTTP_PROXY", "http://127.0.0.1:7890");
+    const mockFetch = installMockFetch((input: RequestInfo | URL) =>
+      Promise.resolve({
+        ok: true,
+        status: 200,
+        headers: makeHeaders({ "content-type": "text/plain" }),
+        text: async () => "proxy body",
+        url: requestUrl(input),
+      } as Response),
+    );
+    const tool = createFetchTool({ firecrawl: { enabled: false } });
+
+    await tool?.execute?.("call", { url: "https://example.com/proxy" });
+
+    const requestInit = mockFetch.mock.calls[0]?.[1] as
+      | (RequestInit & { dispatcher?: unknown })
+      | undefined;
+    expect(requestInit?.dispatcher).toBeInstanceOf(EnvHttpProxyAgent);
+  });
+
   // NOTE: Test for wrapping url/finalUrl/warning fields requires DNS mocking.
   // The sanitization of these fields is verified by external-content.test.ts tests.