diff --git a/docs/release-control/v6/internal/subsystems/alerts.md b/docs/release-control/v6/internal/subsystems/alerts.md
index 9d7946179e..d7ad6e1cce 100644
--- a/docs/release-control/v6/internal/subsystems/alerts.md
+++ b/docs/release-control/v6/internal/subsystems/alerts.md
@@ -1867,6 +1867,23 @@ well as its alerts.
 `internal/alerts/host_unraid_lifecycle_test.go` pins the clear, the holds, the
 restarted count and the pending-run and count cleanup.
 
+### Proxmox node cleanup keeps platform metric alerts
+
+`CleanupAlertsForNodes` runs on every Proxmox node poll (and every mock alert
+tick) and removes alerts whose `Node` is not a current Proxmox node or PBS
+instance. Kubernetes, TrueNAS and vSphere metric alerts carry a cluster or
+platform host in `Node` and a display label such as `TrueNAS Disk` or
+`Kubernetes Pod` in `metadata.resourceType`, which the preserve list's
+platform words never matched. The cleanup used to delete them silently on
+each poll while their reducer incident stayed firing, so the next evaluation
+re-created each one and handed it to the alert callback again as a new
+alert. `shouldPreserveAlertOutsideNodeCleanup` now keeps any alert carrying
+`metadata.platformType`, or whose label maps through
+`CanonicalAlertResourceType` to a Kubernetes, TrueNAS or vSphere type.
+`TestCleanupAlertsForNodesKeepsPlatformMetricAlerts` in
+`internal/alerts/alerts_test.go` pins both signals, and its
+sibling pins that a guest alert on a removed Proxmox node is still removed.
+
 ### Configured flapping thresholds remain reachable
 
 Every accepted positive `FlappingThreshold`, including values above ten, must
diff --git a/internal/alerts/active_cleanup.go b/internal/alerts/active_cleanup.go
index 4da24fa05d..2fdfcd34fc 100644
--- a/internal/alerts/active_cleanup.go
+++ b/internal/alerts/active_cleanup.go
@@ -4,6 +4,7 @@ import (
 	"strings"
 	"time"
 
+	alertconfig "github.com/rcourtman/pulse-go-rewrite/internal/alerts/config"
 	alertspecs "github.com/rcourtman/pulse-go-rewrite/internal/alerts/specs"
 	"github.com/rcourtman/pulse-go-rewrite/internal/unifiedresources"
 	"github.com/rs/zerolog/log"
@@ -264,6 +265,15 @@ func shouldPreserveAlertOutsideNodeCleanup(alertID string, alert *Alert) bool {
 	if alert.CanonicalKind == string(alertspecs.AlertSpecKindProviderIncident) {
 		return true
 	}
+	// Kubernetes, TrueNAS and vSphere metric alerts carry a display label such
+	// as "TrueNAS Disk" or "Kubernetes Pod" in resourceType, which the platform
+	// words below never matched, and a cluster or host in Node rather than a
+	// Proxmox node. Every Proxmox poll used to delete them silently, and the
+	// next evaluation raised them again as new alerts.
+	if metadataStringValue(alert.Metadata, alertPlatformTypeKey) != "" ||
+		isUnifiedModernPlatformAlertType(alertconfig.CanonicalAlertResourceType(alertMetadataResourceType(alert))) {
+		return true
+	}
 
 	switch alertMetadataResourceType(alert) {
 	case string(unifiedresources.ResourceTypeAgent),
diff --git a/internal/alerts/alerts_test.go b/internal/alerts/alerts_test.go
index f4c4463c5e..f0ad060e0f 100644
--- a/internal/alerts/alerts_test.go
+++ b/internal/alerts/alerts_test.go
@@ -12628,6 +12628,82 @@ func TestCleanupAlertsForNodes(t *testing.T) {
 	})
 }
 
+// TestCleanupAlertsForNodesKeepsPlatformMetricAlerts pins that the Proxmox
+// node cleanup, which runs on every Proxmox poll, leaves Kubernetes, TrueNAS
+// and vSphere metric alerts alone. Their Node is a cluster or platform host,
+// never a Proxmox node, and their resourceType is a display label.
+func TestCleanupAlertsForNodesKeepsPlatformMetricAlerts(t *testing.T) {
+	m := newTestManager(t)
+	configureUnifiedEvalManager(t, m, unifiedEvalBaseConfig())
+
+	inputs := []*UnifiedResourceInput{
+		{ID: "physical-disk:truenas-main/sda", Type: "truenas-disk", Name: "sda", Node: "truenas-main", Instance: "TrueNAS", Temperature: &UnifiedResourceMetric{Value: 80, Percent: 80}},
+		{ID: "storage:truenas-main/pool:tank", Type: "truenas-pool", Name: "tank", Node: "truenas-main", Instance: "TrueNAS", Disk: &UnifiedResourceMetric{Percent: 95}},
+		{ID: "k8s:prod:pod:api", Type: "pod", Name: "api", Node: "k8s-node-1", Instance: "prod", CPU: &UnifiedResourceMetric{Percent: 99}},
+		{ID: "vmware:vc:vm:app-01", Type: "vmware-vm", Name: "app-01", Node: "esxi-01", Instance: "vc", CPU: &UnifiedResourceMetric{Percent: 99}},
+	}
+	for _, input := range inputs {
+		m.CheckUnifiedResource(input)
+	}
+	platformAlerts := alertKeys(m)
+	if len(platformAlerts) != len(inputs) {
+		t.Fatalf("expected one alert per platform resource, got %v", platformAlerts)
+	}
+
+	m.CleanupAlertsForNodes(map[string]bool{"pve1": true})
+
+	for _, alertID := range platformAlerts {
+		if _, exists := testLookupActiveAlert(t, m, alertID); !exists {
+			t.Fatalf("Proxmox node cleanup removed platform alert %q; remaining %v", alertID, alertKeys(m))
+		}
+	}
+
+	// The platform id alone keeps an alert whose label is not recognised.
+	m.mu.Lock()
+	labels := make(map[*Alert]interface{}, len(m.activeAlerts))
+	for _, alert := range m.activeAlerts {
+		labels[alert] = alert.Metadata["resourceType"]
+		alert.Metadata["resourceType"] = "Unrecognised"
+	}
+	m.mu.Unlock()
+	m.CleanupAlertsForNodes(map[string]bool{"pve1": true})
+	if got := alertKeys(m); len(got) != len(platformAlerts) {
+		t.Fatalf("platform alerts removed despite their platformType: %v", got)
+	}
+	m.mu.Lock()
+	for alert, label := range labels {
+		alert.Metadata["resourceType"] = label
+	}
+	m.mu.Unlock()
+
+	// A legacy-shaped alert whose metadata predates platformType is still kept
+	// by its display label.
+	m.mu.Lock()
+	for _, alert := range m.activeAlerts {
+		delete(alert.Metadata, alertPlatformTypeKey)
+	}
+	m.mu.Unlock()
+	m.CleanupAlertsForNodes(map[string]bool{"pve1": true})
+	if got := alertKeys(m); len(got) != len(platformAlerts) {
+		t.Fatalf("display-label platform alerts removed without platformType: %v", got)
+	}
+}
+
+// The cleanup still removes a Proxmox guest alert whose node left the estate.
+func TestCleanupAlertsForNodesStillRemovesMissingProxmoxNodeAlerts(t *testing.T) {
+	m := newTestManager(t)
+	configureUnifiedEvalManager(t, m, unifiedEvalBaseConfig())
+
+	m.CheckUnifiedResource(&UnifiedResourceInput{ID: "pve-gone:node-gone:101", Type: "vm", Name: "vm-101", Node: "node-gone", Instance: "pve-gone", CPU: &UnifiedResourceMetric{Percent: 99}})
+	if len(alertKeys(m)) != 1 {
+		t.Fatalf("expected the guest CPU alert, got %v", alertKeys(m))
+	}
+	m.CleanupAlertsForNodes(map[string]bool{"pve1": true})
+	if got := alertKeys(m); len(got) != 0 {
+		t.Fatalf("guest alert on a removed node survived cleanup: %v", got)
+	}
+}
+
 func TestCheckZFSPoolHealth(t *testing.T) {
 	// t.Parallel()
 	poolStateAlertID := buildCanonicalStateID("local-zfs/zfs-pool:rpool", "local-zfs/zfs-pool:rpool-state")