fix(ai): stop streams getting cut off and keep tool steps across messages

src/backend/tests/utils/safe-outbound-fetch.test.ts

@@ -5,6 +5,7 @@ import type { LookupAddress, LookupOptions } from "dns";
 import {
   createDnsLookupHook,
   isBlockedAddress,
+  outboundIdleTimeout,
   readResponseTextLimited,
   safeOutboundFetch,
 } from "../../utils/safe-outbound-fetch.js";
@@ -282,6 +283,17 @@ describe("safeOutboundFetch", () => {
   }, 10_000);
 });
 
+describe("outboundIdleTimeout", () => {
+  it("keeps undici's 5 minute default as the floor", () => {
+    expect(outboundIdleTimeout()).toBe(300_000);
+    expect(outboundIdleTimeout(30_000)).toBe(300_000);
+  });
+
+  it("raises the idle timeout for a longer request timeout", () => {
+    expect(outboundIdleTimeout(600_000)).toBe(600_000);
+  });
+});
+
 describe("redirect handling", () => {
   it.each([undefined, "error", "follow", "manual"] as const)(
     "never follows redirects with mode %s",