diff --git a/docs/release-control/v6/internal/subsystems/alerts.md b/docs/release-control/v6/internal/subsystems/alerts.md
index 3c89b76df0..7d9fc4f39e 100644
--- a/docs/release-control/v6/internal/subsystems/alerts.md
+++ b/docs/release-control/v6/internal/subsystems/alerts.md
@@ -15,6 +15,35 @@
 
 ## Purpose
 
+### Retained guest observations are not alert evidence
+
+Guest memory marked `last-known`, `unavailable` or an unknown observation state
+cannot start, advance, refresh or resolve a memory incident. A VM filesystem
+read with a nonempty `diskStatusReason`, including retained `prev-*` values,
+or unavailable aggregate usage is likewise not current disk evidence. It cannot
+evaluate either aggregate or per-filesystem thresholds, replace an aggregate
+incident with filesystem incidents, or clear filesystem alerts as if a failed
+or expired inventory were authoritative removal. Metric filters do not match
+these unavailable memory/disk values, including a fabricated healthy zero.
+
+Existing incidents retain their last trusted value, occurrence, acknowledgement,
+observation time and lifecycle/delivery evidence until a current observation
+resumes evaluation. Successful current inventory still resolves removed
+filesystems. Explicit disablement, suppression and stopped-guest behavior remain
+effective independently of telemetry, including per-filesystem disable overrides
+on retained identities. Legacy unannotated memory and independent
+current PVE/Pulse-agent memory/disks keep their existing policy, even while QGA
+is deferred; current CPU and I/O continue to evaluate. Producers own freshness;
+no new age threshold, QGA request, payload, alert family or UI surface is added.
+
+`guest_observation_test.go` pins typed/pointer VM/LXC observation admission,
+delayed breaches, canonical incident/acknowledgement/ledger continuity, filters,
+fresh recovery and removal, independent metrics and deliberate disablement.
+`TestGuestBackupDeferralAlertObservationLifecycle` connects actual HTTP client,
+poll builder, retained snapshot, unified view, History and the production alert
+call. These are synthetic source proofs, not native backup/thaw, containing
+release, installed delivery or external recipient acceptance.
+
 ### Pulse system alerts retain their service scope in the existing UI
 
 The `pulse-system-` identity prefix or explicit `systemAlert: true` metadata
diff --git a/internal/alerts/filter_evaluation.go b/internal/alerts/filter_evaluation.go
index 5741e176a1..d8c0954130 100644
--- a/internal/alerts/filter_evaluation.go
+++ b/internal/alerts/filter_evaluation.go
@@ -19,18 +19,20 @@ func (m *Manager) evaluateFilterCondition(guest any, condition FilterCondition)
 
 // guestMetrics holds common metrics for filter evaluation
 type guestMetrics struct {
-	CPU            float64 // CPU usage as percentage (0-100)
-	MemUsage       float64 // Memory usage percentage
-	DiskUsage      float64 // Disk usage percentage
-	DiskRead       int64   // Bytes/s
-	DiskWrite      int64   // Bytes/s
-	NetworkIn      int64   // Bytes/s
-	NetworkOut     int64   // Bytes/s
-	IORateValidity models.IORateValidity
-	Name           string
-	Node           string
-	ID             string
-	Status         string
+	CPU               float64 // CPU usage as percentage (0-100)
+	MemUsage          float64 // Memory usage percentage
+	DiskUsage         float64 // Disk usage percentage
+	MemoryUnavailable bool
+	DiskUnavailable   bool
+	DiskRead          int64 // Bytes/s
+	DiskWrite         int64 // Bytes/s
+	NetworkIn         int64 // Bytes/s
+	NetworkOut        int64 // Bytes/s
+	IORateValidity    models.IORateValidity
+	Name              string
+	Node              string
+	ID                string
+	Status            string
 }
 
 // extractGuestMetrics extracts common metrics from a VM or Container
@@ -57,8 +59,14 @@ func evaluateGuestCondition(metrics guestMetrics, condition FilterCondition) boo
 		case "cpu":
 			value = metrics.CPU
 		case "memory":
+			if metrics.MemoryUnavailable {
+				return false
+			}
 			value = metrics.MemUsage
 		case "disk":
+			if metrics.DiskUnavailable {
+				return false
+			}
 			value = metrics.DiskUsage
 		case "diskread":
 			if !validity.DiskRead {
diff --git a/internal/alerts/guest.go b/internal/alerts/guest.go
index b185ea1d30..25963829ef 100644
--- a/internal/alerts/guest.go
+++ b/internal/alerts/guest.go
@@ -259,8 +259,11 @@ func (m *Manager) CheckGuest(guest any, instanceName string) {
 		memoryMetric = &UnifiedResourceMetric{Percent: memUsage}
 	}
 	diskReadMetric, diskWriteMetric, networkInMetric, networkOutMetric := guestIORateMetrics(snapshot)
-	diskMetric := &UnifiedResourceMetric{Percent: diskUsage}
-	if len(disks) > 0 {
+	var diskMetric *UnifiedResourceMetric
+	if !snapshot.DiskUnavailable {
+		diskMetric = &UnifiedResourceMetric{Percent: diskUsage}
+	}
+	if !snapshot.DiskUnavailable && len(disks) > 0 {
 		seenAggregateDiskKeys := make(map[string]struct{})
 		for idx, disk := range disks {
 			if disk.Total <= 0 || disk.Usage < 0 {
@@ -295,6 +298,12 @@ func (m *Manager) CheckGuest(guest any, instanceName string) {
 		NetworkOut: networkOutMetric,
 	}, thresholds, evalOpts)
 
+	// Retained/failed filesystem evidence is useful to display, but neither
+	// its values nor an empty result can establish a breach, recovery or disk
+	// removal. CPU/I/O and independent current memory were evaluated above.
+	// Still apply explicit per-filesystem disablement to retained identities;
+	// this is operator policy, not recovery inferred from an old value.
+
 	if len(disks) > 0 {
 		seenDiskKeys := make(map[string]struct{})
 		seenDiskResources := make(map[string]struct{})
@@ -331,6 +340,12 @@ func (m *Manager) CheckGuest(guest any, instanceName string) {
 					effectiveDiskThreshold = ensureHysteresisThreshold(diskOverride.Disk)
 				}
 			}
+			if snapshot.DiskUnavailable {
+				if effectiveDiskThreshold == nil || effectiveDiskThreshold.Trigger <= 0 {
+					m.clearAlert(canonicalMetricStateID(perDiskResourceID, "disk"))
+				}
+				continue
+			}
 
 			log.Debug().
 				Str("guest", name).
@@ -376,11 +391,15 @@ func (m *Manager) CheckGuest(guest any, instanceName string) {
 				MonitorOnly: monitorOnly,
 			})
 		}
-		if cleared := m.cleanupGuestDiskAlerts(guestID, seenDiskResources); cleared > 0 {
-			m.saveActiveAlertsAsync("guest-disk-set-changed")
+		if !snapshot.DiskUnavailable {
+			if cleared := m.cleanupGuestDiskAlerts(guestID, seenDiskResources); cleared > 0 {
+				m.saveActiveAlertsAsync("guest-disk-set-changed")
+			}
+		}
+	} else if !snapshot.DiskUnavailable {
+		if cleared := m.cleanupGuestDiskAlerts(guestID, nil); cleared > 0 {
+			m.saveActiveAlertsAsync("guest-disk-alerts-cleared")
 		}
-	} else if cleared := m.cleanupGuestDiskAlerts(guestID, nil); cleared > 0 {
-		m.saveActiveAlertsAsync("guest-disk-alerts-cleared")
 	}
 }
 
diff --git a/internal/alerts/guest_observation_test.go b/internal/alerts/guest_observation_test.go
new file mode 100644
index 0000000000..d231e727a3
--- /dev/null
+++ b/internal/alerts/guest_observation_test.go
@@ -0,0 +1,220 @@
+package alerts
+
+import (
+	"bytes"
+	"encoding/json"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/rcourtman/pulse-go-rewrite/internal/alerts/eventlog"
+	"github.com/rcourtman/pulse-go-rewrite/internal/models"
+)
+
+func guestObservationManager(t *testing.T) *Manager {
+	t.Helper()
+	m := newEventLogManager(t)
+	cfg := characterizationBaseConfig()
+	cfg.GuestDefaults.DiskWrite = &HysteresisThreshold{Trigger: 5, Clear: 4}
+	m.UpdateConfig(cfg)
+	disableTestTimeThresholds(m)
+	return m
+}
+
+func guestObservationVM() models.VM {
+	return models.VM{
+		ID: "site:node:105", VMID: 105, Name: "database", Node: "node", Instance: "site", Type: "qemu", Status: "running",
+		Memory: models.Memory{Total: 1000, Used: 960, Free: 40, Usage: 96,
+			Observation: models.MemoryObservation{State: "current", Source: "guest-agent-meminfo", ObservedAt: time.Now().Add(-time.Second)}},
+		Disk: models.Disk{Total: 1000, Used: 980, Free: 20, Usage: 98},
+		Disks: []models.Disk{{Total: 1000, Used: 980, Free: 20, Usage: 98, Mountpoint: "/", Device: "/dev/vda"},
+			{Total: 1000, Used: 980, Free: 20, Usage: 98, Mountpoint: "/data", Device: "/dev/vdb"}},
+		IORateValidity: models.IORateValidity{Explicit: true},
+	}
+}
+
+func guestObservationBytes(t *testing.T, m *Manager) []byte {
+	t.Helper()
+	active := m.GetActiveAlerts()
+	sort.Slice(active, func(i, j int) bool { return active[i].ID < active[j].ID })
+	data, err := json.Marshal(active)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return data
+}
+
+func TestGuestAlertRetainedObservationsCannotFire(t *testing.T) {
+	for _, state := range []string{"last-known", "unavailable", "unknown-version"} {
+		for _, kind := range []string{"vm", "vm-pointer", "lxc", "lxc-pointer"} {
+			t.Run(kind+"/"+state, func(t *testing.T) {
+				m := guestObservationManager(t)
+				vm := guestObservationVM()
+				vm.Memory.Observation.State = state
+				vm.DiskStatusReason, vm.GuestAgentStatus = "prev-vm-locked", "deferred"
+				var guest any = vm
+				switch kind {
+				case "vm-pointer":
+					guest = &vm
+				case "lxc", "lxc-pointer":
+					ct := models.Container{ID: vm.ID, VMID: vm.VMID, Name: vm.Name, Node: vm.Node, Instance: vm.Instance, Status: vm.Status, Memory: vm.Memory,
+						Disk: models.Disk{Usage: 10}, IORateValidity: vm.IORateValidity}
+					guest = ct
+					if kind == "lxc-pointer" {
+						guest = &ct
+					}
+				}
+				for poll := 0; poll < 4; poll++ {
+					m.CheckGuest(guest, "site")
+				}
+				if got := m.GetActiveAlerts(); len(got) != 0 {
+					t.Fatalf("retained observations opened alerts: %+v", got)
+				}
+				if len(queryAlertEvents(t, m, eventlog.Filter{})) != 0 {
+					t.Fatal("retained observations emitted lifecycle/delivery evidence")
+				}
+			})
+		}
+	}
+}
+
+func TestGuestAlertUnavailableDiskInventoryIsNotRecovery(t *testing.T) {
+	for _, reason := range []string{"prev-vm-locked", "prev-lock-unverified", "agent-timeout", "agent-not-running", "permission-denied", "agent-error", "no-filesystems"} {
+		t.Run(reason, func(t *testing.T) {
+			m := guestObservationManager(t)
+			vm := guestObservationVM()
+			m.CheckGuest(vm, "site")
+			active := m.GetActiveAlerts()
+			if len(active) != 3 {
+				t.Fatalf("current memory and two filesystems must fire: %+v", active)
+			}
+			for _, a := range active {
+				if err := m.AcknowledgeAlert(a.ID, "operator"); err != nil {
+					t.Fatal(err)
+				}
+			}
+			before := guestObservationBytes(t, m)
+			events := len(queryAlertEvents(t, m, eventlog.Filter{}))
+			vm.Memory.Usage, vm.Memory.Used, vm.Memory.Free = 10, 100, 900
+			vm.Memory.Observation.State = "last-known"
+			vm.Disk.Usage, vm.DiskStatusReason = 10, reason
+			for i := range vm.Disks {
+				vm.Disks[i].Usage = 10
+			}
+			m.CheckGuest(vm, "site")
+			vm.Disks = nil // Failed/expired retained inventory is not removal.
+			vm.Disk.Usage = -1
+			for poll := 0; poll < 4; poll++ {
+				m.CheckGuest(vm, "site")
+			}
+			if after := guestObservationBytes(t, m); !bytes.Equal(before, after) {
+				t.Fatalf("unknown observation changed incident values/identity/ack/age: before=%s after=%s", before, after)
+			}
+			if len(queryAlertEvents(t, m, eventlog.Filter{})) != events {
+				t.Fatal("unknown observation emitted lifecycle/delivery evidence")
+			}
+			vm.Memory.Observation.State = "current"
+			vm.Disk.Usage, vm.DiskStatusReason = 10, ""
+			vm.Disks = []models.Disk{{Total: 1000, Used: 100, Free: 900, Usage: 10, Mountpoint: "/", Device: "/dev/vda"}}
+			m.CheckGuest(vm, "site") // Fresh recovery plus authoritative removal of /data.
+			m.CheckGuest(vm, "site")
+			if len(m.GetActiveAlerts()) != 0 || len(queryAlertEvents(t, m, eventlog.Filter{Types: []string{eventlog.TypeResolved}})) != 3 {
+				t.Fatal("fresh recovery/removal must resolve each original incident exactly once")
+			}
+		})
+	}
+}
+
+func TestGuestAlertRetainedAggregateAndPendingCannotAdvance(t *testing.T) {
+	m := guestObservationManager(t)
+	vm := guestObservationVM()
+	vm.Disks = nil
+	vm.Memory.Usage = 90
+	m.mu.Lock()
+	m.config.MetricTimeThresholds = map[string]map[string]int{"guest": {"memory": 60, "disk": 60}}
+	m.mu.Unlock()
+	m.CheckGuest(vm, "site")
+	if len(m.GetActiveAlerts()) != 0 {
+		t.Fatal("fresh warning observations should begin their delay, not fire")
+	}
+	m.mu.Lock()
+	m.core.ShiftPending(-2 * time.Minute)
+	m.mu.Unlock()
+	vm.Memory.Observation.State, vm.DiskStatusReason = "last-known", "prev-agent-cooldown"
+	for poll := 0; poll < 4; poll++ {
+		m.CheckGuest(vm, "site")
+	}
+	if len(m.GetActiveAlerts()) != 0 {
+		t.Fatal("retained memory/disk promoted a delayed observation to an incident")
+	}
+	vm.Memory.Observation.State, vm.DiskStatusReason = "current", ""
+	m.CheckGuest(vm, "site")
+	if len(m.GetActiveAlerts()) != 2 {
+		t.Fatal("fresh evidence must resume the existing delay policy")
+	}
+}
+
+func TestGuestAlertFreshIndependentMetricsAndDisablement(t *testing.T) {
+	for _, state := range []string{"", "current"} {
+		t.Run("legacy-or-current/"+state, func(t *testing.T) {
+			m := guestObservationManager(t)
+			vm := guestObservationVM()
+			vm.Memory.Observation.State = state
+			// Guest-agent state alone cannot suppress independent current data.
+			vm.GuestAgentStatus, vm.Lock = "deferred", "backup"
+			vm.Memory.Observation.Source = "agent"
+			m.CheckGuest(vm, "site")
+			if len(m.GetActiveAlerts()) != 3 {
+				t.Fatal("legacy/current independent memory and filesystems were suppressed")
+			}
+			vm.Memory.Observation.State, vm.DiskStatusReason = "last-known", "prev-vm-locked"
+			cfg := m.GetConfig()
+			cfg.GuestDefaults.Memory = &HysteresisThreshold{Trigger: -1}
+			cfg.GuestDefaults.Disk = &HysteresisThreshold{Trigger: -1}
+			m.UpdateConfig(cfg)
+			m.CheckGuest(vm, "site")
+			if len(m.GetActiveAlerts()) != 0 {
+				t.Fatal("explicit rule disablement must remain independent of telemetry")
+			}
+		})
+	}
+	m := guestObservationManager(t)
+	vm := guestObservationVM()
+	vm.Memory.Observation.State, vm.DiskStatusReason = "last-known", "prev-vm-locked"
+	vm.CPU, vm.DiskWrite = .9, 10*1024*1024
+	vm.IORateValidity.DiskWrite = true
+	m.CheckGuest(vm, "site")
+	active := m.GetActiveAlerts()
+	if len(active) != 2 {
+		t.Fatalf("current CPU/I/O should still fire, retained memory/disk should not: %+v", active)
+	}
+	for _, a := range active {
+		if a.Type != "cpu" && a.Type != "diskWrite" {
+			t.Fatalf("unexpected retained metric alert: %+v", a)
+		}
+	}
+}
+
+func TestGuestFiltersDoNotUseRetainedObservations(t *testing.T) {
+	m := guestObservationManager(t)
+	vm := guestObservationVM()
+	for _, field := range []string{"memory", "disk"} {
+		for _, op := range []string{">", "<", "=="} {
+			condition := FilterCondition{Type: "metric", Field: field, Operator: op, Value: 96.0}
+			vm.Memory.Observation.State, vm.DiskStatusReason = "last-known", "prev-vm-locked"
+			if m.evaluateVMCondition(vm, condition) || m.evaluateFilterCondition(&vm, condition) {
+				t.Fatalf("retained %s matched %s", field, op)
+			}
+		}
+	}
+	vm.Memory.Observation.State, vm.DiskStatusReason = "current", ""
+	for _, field := range []string{"memory", "disk"} {
+		if !m.evaluateVMCondition(vm, FilterCondition{Type: "metric", Field: field, Operator: ">", Value: 90.0}) {
+			t.Fatalf("fresh %s could not match", field)
+		}
+	}
+	vm.Memory = models.UnavailableMemory(1000)
+	if m.evaluateVMCondition(vm, FilterCondition{Type: "metric", Field: "memory", Operator: "<", Value: 90.0}) {
+		t.Fatal("unavailable memory was treated as a measured zero in a filter")
+	}
+}
diff --git a/internal/alerts/guest_snapshot.go b/internal/alerts/guest_snapshot.go
index f9741f9647..9cbcc805e0 100644
--- a/internal/alerts/guest_snapshot.go
+++ b/internal/alerts/guest_snapshot.go
@@ -28,9 +28,10 @@ type guestSnapshot struct {
 
 	CPUPercent float64
 	MemUsage   float64
-	// MemoryUnavailable prevents a missing cache-aware sample from clearing a
-	// real alert or starting a false one.
+	// Unavailable observations include retained display values. They cannot
+	// supply a new breach, recovery, filter match or filesystem removal.
 	MemoryUnavailable bool
+	DiskUnavailable   bool
 	DiskUsage         float64
 	DiskRead          int64
 	DiskWrite         int64
@@ -81,18 +82,20 @@ func (g guestSnapshot) resourceType() string {
 
 func (g guestSnapshot) metrics() guestMetrics {
 	return guestMetrics{
-		CPU:            g.CPUPercent,
-		MemUsage:       g.MemUsage,
-		DiskUsage:      g.DiskUsage,
-		DiskRead:       g.DiskRead,
-		DiskWrite:      g.DiskWrite,
-		NetworkIn:      g.NetworkIn,
-		NetworkOut:     g.NetworkOut,
-		IORateValidity: g.IORateValidity,
-		Name:           g.Name,
-		Node:           g.Node,
-		ID:             g.ID,
-		Status:         g.Status,
+		CPU:               g.CPUPercent,
+		MemUsage:          g.MemUsage,
+		DiskUsage:         g.DiskUsage,
+		MemoryUnavailable: g.MemoryUnavailable,
+		DiskUnavailable:   g.DiskUnavailable,
+		DiskRead:          g.DiskRead,
+		DiskWrite:         g.DiskWrite,
+		NetworkIn:         g.NetworkIn,
+		NetworkOut:        g.NetworkOut,
+		IORateValidity:    g.IORateValidity,
+		Name:              g.Name,
+		Node:              g.Node,
+		ID:                g.ID,
+		Status:            g.Status,
 	}
 }
 
@@ -108,7 +111,8 @@ func guestSnapshotFromVM(vm models.VM) guestSnapshot {
 		Lock:              vm.Lock,
 		CPUPercent:        unifiedresources.ProxmoxGuestCPUPercent(vm.CPU),
 		MemUsage:          vm.Memory.Usage,
-		MemoryUnavailable: vm.Memory.UsageUnavailable,
+		MemoryUnavailable: guestMemoryUnavailableForAlerts(vm.Memory),
+		DiskUnavailable:   vm.DiskStatusReason != "" || vm.Disk.Usage < 0,
 		DiskUsage:         vm.Disk.Usage,
 		DiskRead:          vm.DiskRead,
 		DiskWrite:         vm.DiskWrite,
@@ -133,7 +137,8 @@ func guestSnapshotFromContainer(container models.Container) guestSnapshot {
 		Lock:              container.Lock,
 		CPUPercent:        unifiedresources.ProxmoxGuestCPUPercent(container.CPU),
 		MemUsage:          container.Memory.Usage,
-		MemoryUnavailable: container.Memory.UsageUnavailable,
+		MemoryUnavailable: guestMemoryUnavailableForAlerts(container.Memory),
+		DiskUnavailable:   container.Disk.Usage < 0,
 		DiskUsage:         container.Disk.Usage,
 		DiskRead:          container.DiskRead,
 		DiskWrite:         container.DiskWrite,
@@ -146,6 +151,13 @@ func guestSnapshotFromContainer(container models.Container) guestSnapshot {
 	}.normalizeCollections()
 }
 
+func guestMemoryUnavailableForAlerts(memory models.Memory) bool {
+	// The producer owns freshness and source selection. Legacy values without
+	// an observation retain their existing behavior; do not infer freshness
+	// from disk/QGA state, since PVE or a linked Pulse agent can be independent.
+	return memory.UsageUnavailable || (memory.Observation.State != "" && memory.Observation.State != "current")
+}
+
 func guestKindFromType(guestType string) guestKind {
 	switch strings.ToLower(strings.TrimSpace(guestType)) {
 	case "qemu", "vm":
diff --git a/internal/alerts/guest_snapshot_test.go b/internal/alerts/guest_snapshot_test.go
index 28c7e4e65f..2f89b24eda 100644
--- a/internal/alerts/guest_snapshot_test.go
+++ b/internal/alerts/guest_snapshot_test.go
@@ -19,6 +19,72 @@ func TestGuestSnapshotResourceTypeUsesCanonicalSystemContainer(t *testing.T) {
 	}
 }
 
+func TestGuestSnapshotObservationAvailability(t *testing.T) {
+	for _, test := range []struct {
+		name       string
+		memory     models.Memory
+		disk       models.Disk
+		reason     string
+		wantMemory bool
+		wantDisk   bool
+	}{
+		{name: "legacy measured zero", memory: models.Memory{}, disk: models.Disk{}},
+		{name: "current independent read", memory: models.Memory{Usage: 96, Observation: models.MemoryObservation{State: "current", Source: "agent"}}, disk: models.Disk{Usage: 98}},
+		{name: "retained memory only", memory: models.Memory{Usage: 96, Observation: models.MemoryObservation{State: "last-known"}}, disk: models.Disk{Usage: 98}, wantMemory: true},
+		{name: "unavailable numeric placeholder", memory: models.Memory{Usage: 0, Observation: models.MemoryObservation{State: "unavailable"}}, wantMemory: true},
+		{name: "unknown observation version", memory: models.Memory{Usage: 96, Observation: models.MemoryObservation{State: "future-version"}}, wantMemory: true},
+		{name: "explicit unavailable overrides current", memory: models.Memory{Usage: 96, UsageUnavailable: true, Observation: models.MemoryObservation{State: "current"}}, wantMemory: true},
+		{name: "retained filesystem only", memory: models.Memory{Usage: 96}, disk: models.Disk{Usage: 98}, reason: "prev-vm-locked", wantDisk: true},
+		{name: "failed empty filesystem inventory", memory: models.Memory{Usage: 96}, disk: models.Disk{Usage: -1}, reason: "agent-error", wantDisk: true},
+		{name: "legacy unavailable aggregate", memory: models.Memory{Usage: 96}, disk: models.Disk{Usage: -1}, wantDisk: true},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			// A deferred QGA session does not by itself make independent
+			// selected memory or Pulse-agent filesystems unavailable.
+			vm := models.VM{Memory: test.memory, Disk: test.disk, DiskStatusReason: test.reason, GuestAgentStatus: "deferred"}
+			for _, guest := range []any{vm, &vm} {
+				snapshot, ok := extractGuestSnapshot(guest)
+				if !ok || snapshot.MemoryUnavailable != test.wantMemory || snapshot.DiskUnavailable != test.wantDisk {
+					t.Fatalf("observation flags lost: %+v", snapshot)
+				}
+				metrics := snapshot.metrics()
+				if metrics.MemoryUnavailable != test.wantMemory || metrics.DiskUnavailable != test.wantDisk || metrics.MemUsage != test.memory.Usage || metrics.DiskUsage != test.disk.Usage {
+					t.Fatal("filter projection lost availability or rewrote retained values")
+				}
+			}
+			ct := models.Container{Memory: test.memory, Disk: test.disk}
+			for _, guest := range []any{ct, &ct} {
+				snapshot, _ := extractGuestSnapshot(guest)
+				if snapshot.MemoryUnavailable != test.wantMemory || snapshot.DiskUnavailable != (test.disk.Usage < 0) {
+					t.Fatal("LXC observation availability changed with an unrelated VM disk failure")
+				}
+			}
+		})
+	}
+}
+
+func TestGuestAlertRetainedDiskStillHonoursExplicitOverride(t *testing.T) {
+	for _, override := range []ThresholdConfig{{Disabled: true}, {Disk: &HysteresisThreshold{Trigger: -1}}} {
+		m := guestObservationManager(t)
+		vm := guestObservationVM()
+		vm.Memory.Usage = 10
+		m.CheckGuest(vm, "site")
+		if len(m.GetActiveAlerts()) != 2 {
+			t.Fatal("expected two current filesystem incidents")
+		}
+		_, keySource, key := guestDiskIdentity(vm.Disks[0], 0)
+		cfg := m.GetConfig()
+		cfg.Overrides[guestDiskOverrideKey(vm, vm.ID, keySource)] = override
+		m.UpdateConfig(cfg)
+		vm.DiskStatusReason = "prev-vm-locked"
+		m.CheckGuest(vm, "site")
+		active := m.GetActiveAlerts()
+		if len(active) != 1 || active[0].ResourceID == vm.ID+"-disk-"+key {
+			t.Fatalf("explicit filesystem disablement was lost or crossed disk identity: %+v", active)
+		}
+	}
+}
+
 func TestGuestSnapshotUsesCanonicalProxmoxCPUPercent(t *testing.T) {
 	for _, tc := range []struct {
 		name string
diff --git a/internal/monitoring/guest_alert_observation_integration_test.go b/internal/monitoring/guest_alert_observation_integration_test.go
new file mode 100644
index 0000000000..ec6c293914
--- /dev/null
+++ b/internal/monitoring/guest_alert_observation_integration_test.go
@@ -0,0 +1,140 @@
+package monitoring
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/rcourtman/pulse-go-rewrite/internal/alerts"
+	"github.com/rcourtman/pulse-go-rewrite/internal/config"
+	"github.com/rcourtman/pulse-go-rewrite/internal/models"
+	"github.com/rcourtman/pulse-go-rewrite/internal/unifiedresources"
+	"github.com/rcourtman/pulse-go-rewrite/pkg/proxmox"
+)
+
+// Exercise actual HTTP client, builders, saved snapshots, unified views, History
+// and the production alert call. No native QGA or backup is performed.
+func TestGuestBackupDeferralAlertObservationLifecycle(t *testing.T) {
+	const mib = uint64(1024 * 1024)
+	var phase, guestCalls atomic.Int32
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		switch {
+		case strings.HasSuffix(r.URL.Path, "/config"):
+			if phase.Load() == 1 {
+				fmt.Fprint(w, `{"data":{"lock":"backup"}}`)
+			} else {
+				fmt.Fprint(w, `{"data":{}}`)
+			}
+		case strings.HasSuffix(r.URL.Path, "/status/current"):
+			fmt.Fprintf(w, `{"data":{"status":"running","agent":1,"maxmem":%d,"mem":%d}}`, 1000*mib, 1000*mib)
+		case strings.Contains(r.URL.Path, "/agent/"):
+			guestCalls.Add(1)
+			switch {
+			case strings.HasSuffix(r.URL.Path, "file-read"):
+				available := 40 * 1024
+				if phase.Load() == 2 {
+					available = 800 * 1024
+				}
+				json.NewEncoder(w).Encode(map[string]any{"data": map[string]any{"content": fmt.Sprintf("MemTotal: 1024000 kB\nMemFree: 10240 kB\nMemAvailable: %d kB\n", available)}})
+			case strings.HasSuffix(r.URL.Path, "get-fsinfo"):
+				used := 980 * mib
+				if phase.Load() == 2 {
+					used = 200 * mib
+				}
+				fmt.Fprintf(w, `{"data":{"result":[{"mountpoint":"/","type":"ext4","total-bytes":%d,"used-bytes":%d}]}}`, 1000*mib, used)
+			case strings.HasSuffix(r.URL.Path, "network-get-interfaces"):
+				fmt.Fprint(w, `{"data":{"result":[]}}`)
+			case strings.HasSuffix(r.URL.Path, "get-osinfo"):
+				fmt.Fprint(w, `{"data":{"name":"Linux","version":"fixture"}}`)
+			default:
+				fmt.Fprint(w, `{"data":{"result":{"version":"1.0"}}}`)
+			}
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+	client, err := proxmox.NewClient(proxmox.ClientConfig{Host: server.URL, TokenName: "fixture@pve!pulse", TokenValue: "fixture", Timeout: time.Second})
+	if err != nil {
+		t.Fatal(err)
+	}
+	am := alerts.NewManagerWithDataDir(t.TempDir(), alerts.WithoutPersistedAlertRestore())
+	defer am.Stop()
+	cfg := am.GetConfig()
+	cfg.Enabled = true
+	cfg.GuestDefaults.Memory = &alerts.HysteresisThreshold{Trigger: 85, Clear: 80}
+	cfg.GuestDefaults.Disk = &alerts.HysteresisThreshold{Trigger: 90, Clear: 85}
+	cfg.GuestDefaults.CPU = &alerts.HysteresisThreshold{Trigger: 80, Clear: 75}
+	cfg.MetricTimeThresholds = map[string]map[string]int{"guest": {"memory": 0, "disk": 0, "cpu": 0}}
+	am.UpdateConfig(cfg)
+	registry := unifiedresources.NewRegistry(nil)
+	m := &Monitor{config: &config.Config{}, alertManager: am, rateTracker: NewRateTracker(), metricsHistory: NewMetricsHistory(32, time.Hour), guestMetadataLimiter: make(map[string]time.Time)}
+	res := proxmox.ClusterResource{Type: "qemu", Node: "node", Name: "guest", VMID: 105, Status: "running", MaxMem: 1000 * mib, Mem: 1000 * mib, MaxDisk: 1000 * mib}
+	identity := makeGuestID("alert-observation", "node", 105)
+	var previous *models.VM
+	build := func() models.VM {
+		t.Helper()
+		vm, raw, source, notes, at, ok := m.buildVMFromClusterResource(context.Background(), "alert-observation", res, client, identity, nil, previous)
+		if !ok {
+			t.Fatal("VM disappeared")
+		}
+		m.recordGuestSnapshot("alert-observation", "qemu", "node", 105, GuestMemorySnapshot{Status: vm.Status, RetrievedAt: at, MemorySource: source, Memory: vm.Memory, Raw: raw, Notes: notes})
+		m.recordGuestMetrics([]models.VM{vm}, nil, time.Now().Add(-time.Second))
+		registry.IngestSnapshot(models.StateSnapshot{VMs: []models.VM{vm}})
+		next := previousVMFromView(registry.VMs()[0])
+		previous = &next
+		return vm
+	}
+	initial := build()
+	// The observation was made before alert policy became enabled for this VM.
+	// A retained high value must not create an incident upon the next poll.
+	phase.Store(1)
+	before := guestCalls.Load()
+	locked := build()
+	if locked.Memory.Observation.State != "last-known" || !strings.HasPrefix(locked.DiskStatusReason, "prev-") {
+		t.Fatalf("fixture did not produce real last-known evidence: %+v", locked)
+	}
+	m.checkGuestAlertsForVM("alert-observation", locked)
+	if len(am.GetActiveAlerts()) != 0 {
+		t.Fatal("production alert call treated retained backup-lock evidence as current")
+	}
+	// The original current evidence can establish an alert. Subsequent lock
+	// polls must neither refresh its observation nor resolve it on expiry.
+	m.checkGuestAlertsForVM("alert-observation", initial)
+	if len(am.GetActiveAlerts()) != 2 {
+		t.Fatal("current memory/filesystem evidence did not establish two alerts")
+	}
+	for poll := 0; poll < 4; poll++ {
+		m.checkGuestAlertsForVM("alert-observation", build())
+	}
+	if guestCalls.Load() != before || len(am.GetActiveAlerts()) != 2 {
+		t.Fatal("backup deferral queried QGA or lost the original alerts")
+	}
+	for _, a := range am.GetActiveAlerts() {
+		if a.Value != 96 && a.Value != 98 {
+			t.Fatal("retained poll changed the last trusted alert value")
+		}
+	}
+	if got := len(m.metricsHistory.GetGuestMetrics(identity, "memory", time.Hour)); got != 1 {
+		t.Fatalf("retained memory refreshed History: %d points", got)
+	}
+	if got := len(m.metricsHistory.GetGuestMetrics(identity, "disk", time.Hour)); got != 1 {
+		t.Fatalf("retained filesystem refreshed History: %d points", got)
+	}
+	phase.Store(2)
+	entry := m.vmAgentMemCache[guestMemoryCacheKey("alert-observation", "node", 105)]
+	entry.fetchedAt = time.Now().Add(-2 * vmAgentMemCacheTTL)
+	m.vmAgentMemCache[guestMemoryCacheKey("alert-observation", "node", 105)] = entry
+	resumed := build()
+	m.checkGuestAlertsForVM("alert-observation", resumed)
+	if guestCalls.Load() <= before || resumed.Memory.Observation.State != "current" || resumed.DiskStatusReason != "" || len(am.GetActiveAlerts()) != 0 {
+		t.Fatal("fresh unlocked memory/filesystem evidence did not recover the original incidents")
+	}
+}