Preserve guest NICs when only filtered addresses are reported (#1319)

internal/monitoring/guest_metadata.go

@@ -565,6 +565,7 @@ func processGuestNetworkInterfaces(raw []proxmox.VMNetworkInterface) ([]string,
 	for _, iface := range raw {
 		ifaceName := strings.TrimSpace(iface.Name)
 		mac := strings.TrimSpace(iface.HardwareAddr)
+		hadRawAddresses := len(iface.IPAddresses) > 0
 
 		addrSet := make(map[string]struct{})
 		addresses := make([]string, 0, len(iface.IPAddresses))
@@ -604,13 +605,18 @@ func processGuestNetworkInterfaces(raw []proxmox.VMNetworkInterface) ([]string,
 		}
 
 		if len(addresses) == 0 && rxBytes == 0 && txBytes == 0 {
-			if len(iface.IPAddresses) > 0 {
+			lowerName := strings.ToLower(ifaceName)
+			if lowerName == "lo" || lowerName == "loopback" {
 				continue
 			}
-			lowerName := strings.ToLower(ifaceName)
-			if ifaceName == "" || lowerName == "lo" || lowerName == "loopback" {
+			if ifaceName == "" && mac == "" {
 				continue
 			}
+			if hadRawAddresses {
+				// Preserve interface identity even when every reported address was filtered
+				// (for example, link-local-only early guest-agent payloads). Proxmox still
+				// considers this a real guest NIC and the UI should not hide it entirely.
+			}
 			// Preserve named non-loopback interfaces even when early/partial guest-agent
 			// payloads have not populated MAC or IP details yet. The interface identity
 			// is still useful for the VM Summary view and should not wait for a later poll.

internal/monitoring/guest_metadata_test.go

@@ -414,7 +414,7 @@ func TestProcessGuestNetworkInterfaces(t *testing.T) {
 			wantIfaces: []models.GuestNetworkInterface{},
 		},
 		{
-			name: "filter link-local fe80",
+			name: "preserve named interface when only link-local addresses are reported",
 			raw: []proxmox.VMNetworkInterface{
 				{
 					Name:         "eth0",
@@ -425,8 +425,10 @@ func TestProcessGuestNetworkInterfaces(t *testing.T) {
 					},
 				},
 			},
-			wantIPs:    []string{},
-			wantIfaces: []models.GuestNetworkInterface{},
+			wantIPs: []string{},
+			wantIfaces: []models.GuestNetworkInterface{
+				{Name: "eth0", MAC: "00:11:22:33:44:55", Addresses: nil},
+			},
 		},
 		{
 			name: "filter IPv6 loopback ::1",