fix: exclude Tailscale CGNAT addresses from LAN endpoint selection

Tailscale IPs (100.64.0.0/10) were not excluded by isUsableLanIpv4Address,
so when a Tailscale interface was enumerated before a real LAN interface,
resolveLanAdvertisedHost would select the Tailscale IP as the LAN endpoint.
This caused duplicate entries in getDesktopAdvertisedEndpoints (one as
'Local network' from core, one as 'Tailscale IP' from the addon) and the
actual LAN IP would be missing entirely.

Add isTailscaleIpv4Address check to isUsableLanIpv4Address to prevent
Tailscale CGNAT addresses from being selected as LAN endpoints.

Author: cursoragent

apps/desktop/src/serverExposure.ts

@@ -8,6 +8,7 @@ import type {
   AdvertisedEndpointProvider,
   DesktopServerExposureMode,
 } from "@t3tools/contracts";
+import { isTailscaleIpv4Address } from "./tailscaleEndpointProvider.ts";
 
 const DESKTOP_LOOPBACK_HOST = "127.0.0.1";
 const DESKTOP_LAN_BIND_HOST = "0.0.0.0";
@@ -47,7 +48,9 @@ const normalizeOptionalHost = (value: string | undefined): string | undefined =>
 };
 
 const isUsableLanIpv4Address = (address: string): boolean =>
-  !address.startsWith("127.") && !address.startsWith("169.254.");
+  !address.startsWith("127.") &&
+  !address.startsWith("169.254.") &&
+  !isTailscaleIpv4Address(address);
 
 export function resolveLanAdvertisedHost(
   networkInterfaces: NodeJS.Dict<NetworkInterfaceInfo[]>,