fix: include tailnetDns in wide-area beacons

src/gateway/server.ts

@@ -2096,6 +2096,7 @@ export async function startGatewayServer(
           displayName: formatBonjourInstanceName(machineDisplayName),
           tailnetIPv4,
           tailnetIPv6: tailnetIPv6 ?? undefined,
+          tailnetDns,
         });
         defaultRuntime.log(
           `discovery: wide-area DNS-SD ${result.changed ? "updated" : "unchanged"} (${WIDE_AREA_DISCOVERY_DOMAIN} → ${result.zonePath})`,

src/infra/widearea-dns.test.ts

@@ -28,4 +28,20 @@ describe("wide-area DNS-SD zone rendering", () => {
     );
     expect(txt).toContain(`displayName=Mac Studio (Clawdis)`);
   });
+
+  it("includes tailnetDns when provided", () => {
+    const txt = renderWideAreaBridgeZoneText({
+      serial: 2025121701,
+      bridgePort: 18790,
+      displayName: "Mac Studio (Clawdis)",
+      tailnetIPv4: "100.123.224.76",
+      tailnetDns: "peters-mac-studio-1.sheep-coho.ts.net",
+      hostLabel: "studio-london",
+      instanceLabel: "studio-london",
+    });
+
+    expect(txt).toContain(
+      `tailnetDns=peters-mac-studio-1.sheep-coho.ts.net`,
+    );
+  });
 });

src/infra/widearea-dns.ts

@@ -75,6 +75,7 @@ export type WideAreaBridgeZoneOpts = {
   tailnetIPv6?: string;
   instanceLabel?: string;
   hostLabel?: string;
+  tailnetDns?: string;
 };
 
 function renderZone(opts: WideAreaBridgeZoneOpts & { serial: number }): string {
@@ -90,6 +91,9 @@ function renderZone(opts: WideAreaBridgeZoneOpts & { serial: number }): string {
     `transport=bridge`,
     `bridgePort=${opts.bridgePort}`,
   ];
+  if (opts.tailnetDns?.trim()) {
+    txt.push(`tailnetDns=${opts.tailnetDns.trim()}`);
+  }
 
   const records: string[] = [];