fix: skip tailscale dns probe when off

src/gateway/server-discovery.test.ts

@@ -0,0 +1,45 @@
+import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
+
+const getTailnetHostname = vi.hoisted(() => vi.fn());
+
+vi.mock("../infra/tailscale.js", () => ({ getTailnetHostname }));
+
+import { resolveTailnetDnsHint } from "./server-discovery.js";
+
+describe("resolveTailnetDnsHint", () => {
+  const prevTailnetDns = { value: undefined as string | undefined };
+
+  beforeEach(() => {
+    prevTailnetDns.value = process.env.CLAWDBOT_TAILNET_DNS;
+    delete process.env.CLAWDBOT_TAILNET_DNS;
+    getTailnetHostname.mockReset();
+  });
+
+  afterEach(() => {
+    if (prevTailnetDns.value === undefined) {
+      delete process.env.CLAWDBOT_TAILNET_DNS;
+    } else {
+      process.env.CLAWDBOT_TAILNET_DNS = prevTailnetDns.value;
+    }
+  });
+
+  test("returns env hint when disabled", async () => {
+    process.env.CLAWDBOT_TAILNET_DNS = "studio.tailnet.ts.net.";
+    const value = await resolveTailnetDnsHint({ enabled: false });
+    expect(value).toBe("studio.tailnet.ts.net");
+    expect(getTailnetHostname).not.toHaveBeenCalled();
+  });
+
+  test("skips tailscale lookup when disabled", async () => {
+    const value = await resolveTailnetDnsHint({ enabled: false });
+    expect(value).toBeUndefined();
+    expect(getTailnetHostname).not.toHaveBeenCalled();
+  });
+
+  test("uses tailscale lookup when enabled", async () => {
+    getTailnetHostname.mockResolvedValue("host.tailnet.ts.net");
+    const value = await resolveTailnetDnsHint({ enabled: true });
+    expect(value).toBe("host.tailnet.ts.net");
+    expect(getTailnetHostname).toHaveBeenCalledTimes(1);
+  });
+});