Network Type Transition Optimization

Nucleic-Session: 40F8C53A-F001-423A-8607-EAE181DBE14B
Co-authored-by: Nucleic <[email protected]>

NucleicRemote/NucleicRemote/Net/NWFrameChannel.swift

@@ -28,7 +28,15 @@ final class NWFrameChannel: FrameChannel, @unchecked Sendable {
     }
 
     init(endpoint: NWEndpoint) {
-        let params = NWParameters.tcp
+        // Short TCP keepalive so a silently-dead LAN link (Wi-Fi dropped, Mac left the subnet) is
+        // detected in ~15s instead of the OS default of minutes — the belt to the path-monitor's
+        // braces for the case where a path still exists but the route to the Mac is gone.
+        let tcp = NWProtocolTCP.Options()
+        tcp.enableKeepalive = true
+        tcp.keepaliveIdle = 5
+        tcp.keepaliveInterval = 5
+        tcp.keepaliveCount = 2
+        let params = NWParameters(tls: nil, tcp: tcp)
         params.includePeerToPeer = true
         connection = NWConnection(to: endpoint, using: params)
         peerDescription = "\(endpoint)"
@@ -39,6 +47,13 @@ final class NWFrameChannel: FrameChannel, @unchecked Sendable {
         connection.stateUpdateHandler = { [weak self] state in
             switch state {
             case .ready: self?.markReady(); self?.onReady?()
+            case .waiting(let error):
+                // No usable path right now (Wi-Fi dropped, host unreachable). NWConnection would sit
+                // in `.waiting` indefinitely, holding the transport hostage — the core of the "still
+                // on LAN after leaving Wi-Fi" stall. Fail fast so the store falls straight through to
+                // tailnet/relay. (Healthy connections go setup→preparing→ready and never hit this;
+                // the connect-timeout guard covers a wrong-network socket that stays `.preparing`.)
+                self?.onFailed?("waiting: \(error)"); self?.continuation.finish()
             case .failed(let error): self?.onFailed?("\(error)"); self?.continuation.finish()
             case .cancelled: self?.continuation.finish()
             default: break