fix: enumerate IPv6 addresses for mobile pairing on IPv6-only hosts (#9130) (#9131)

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: PannenetsF <fanyunqian.1@bytedance.com>

src/main/ipc/mobile.test.ts

@@ -59,6 +59,41 @@ describe('registerMobileHandlers', () => {
     })
   })
 
+  it('includes IPv6 addresses (ranked after IPv4) and excludes link-local IPv6', () => {
+    networkInterfacesMock.mockReturnValue({
+      en0: [
+        { family: 'IPv4', internal: false, address: '192.168.1.24' },
+        { family: 'IPv6', internal: false, address: 'fe80::1' },
+        { family: 'IPv6', internal: false, address: '2605:340:cd51:2a01:0:2b13:f279:c096' }
+      ],
+      lo0: [{ family: 'IPv6', internal: true, address: '::1' }]
+    })
+
+    registerMobileHandlers({} as never)
+
+    expect(handlers.get('mobile:listNetworkInterfaces')?.()).toEqual({
+      interfaces: [
+        { name: 'en0', address: '192.168.1.24' },
+        { name: 'en0', address: '2605:340:cd51:2a01:0:2b13:f279:c096' }
+      ]
+    })
+  })
+
+  it('returns an IPv6 interface on an IPv6-only host (regression: was empty, breaking mobile pairing)', () => {
+    networkInterfacesMock.mockReturnValue({
+      eth0: [
+        { family: 'IPv6', internal: false, address: '2605:340:cd51:2a01:0:2b13:f279:c096' },
+        { family: 'IPv6', internal: false, address: 'fe80::42:acff:fe11:2' }
+      ]
+    })
+
+    registerMobileHandlers({} as never)
+
+    expect(handlers.get('mobile:listNetworkInterfaces')?.()).toEqual({
+      interfaces: [{ name: 'eth0', address: '2605:340:cd51:2a01:0:2b13:f279:c096' }]
+    })
+  })
+
   it('generates mobile pairing urls with the tailnet address by default', async () => {
     networkInterfacesMock.mockReturnValue({
       en0: [{ family: 'IPv4', internal: false, address: '192.168.1.24' }],

src/main/ipc/mobile.ts

@@ -19,10 +19,20 @@ export type NetworkInterface = {
   address: string
 }
 
+// Why: link-local IPv6 addresses (fe80::/10) require a scope/zone id to be
+// connectable and never work as a QR-advertised pairing host, so they are
+// excluded from the pickable list. The regex covers the full /10 range
+// (fe80: through febf:), not just the fe80: prefix the OS usually assigns.
+function isUsableIPv6Address(address: string): boolean {
+  return !/^fe[89ab][0-9a-f]:/i.test(address)
+}
+
 // Why: the WebSocket transport advertises 0.0.0.0 as its endpoint, which isn't
-// connectable from a mobile device. We enumerate all non-internal IPv4
-// addresses so the user can choose which one to advertise in the QR code
-// (e.g. LAN vs Tailscale).
+// connectable from a mobile device. We enumerate all non-internal IPv4 and
+// (non-link-local) IPv6 addresses so the user can choose which one to advertise
+// in the QR code (e.g. LAN vs Tailscale). IPv6 must be included so pairing works
+// on IPv6-only hosts (e.g. a headless `orca serve` reachable only over IPv6),
+// where an IPv4-only scan returns nothing and the UI reports "no interfaces".
 function getNetworkInterfaces(): NetworkInterface[] {
   const result: NetworkInterface[] = []
   const interfaces = networkInterfaces()
@@ -31,14 +41,26 @@ function getNetworkInterfaces(): NetworkInterface[] {
       continue
     }
     for (const addr of addrs) {
-      if (addr.family === 'IPv4' && !addr.internal) {
+      if (addr.internal) {
+        continue
+      }
+      if (addr.family === 'IPv4') {
+        result.push({ name, address: addr.address })
+      } else if (addr.family === 'IPv6' && isUsableIPv6Address(addr.address)) {
         result.push({ name, address: addr.address })
       }
     }
   }
-  return result.sort(
-    (a, b) => Number(isTailnetIPv4Address(b.address)) - Number(isTailnetIPv4Address(a.address))
-  )
+  // Why: prefer tailnet IPv4 first (most portable across networks), then other
+  // IPv4, then IPv6 as a fallback for IPv6-only environments.
+  return result.sort((a, b) => rankAddress(a.address) - rankAddress(b.address))
+}
+
+function rankAddress(address: string): number {
+  if (isTailnetIPv4Address(address)) {
+    return 0
+  }
+  return address.includes(':') ? 2 : 1
 }
 
 function getDefaultPairingAddress(): string | null {