diff --git a/internal/monitoring/canonical_guardrails_test.go b/internal/monitoring/canonical_guardrails_test.go
index b5c380d7c..b30084293 100644
--- a/internal/monitoring/canonical_guardrails_test.go
+++ b/internal/monitoring/canonical_guardrails_test.go
@@ -462,7 +462,8 @@ func TestGetStateRefreshesLiveAlertSnapshots(t *testing.T) {
 	source := string(data)
 
 	for _, snippet := range []string{
-		"state := m.state.GetSnapshot()",
+		"currentState := m.state",
+		"state := currentState.GetSnapshot()",
 		"state.ActiveAlerts = m.activeAlertsSnapshot()",
 		"state.RecentlyResolved = m.recentlyResolvedAlertsSnapshot()",
 	} {
diff --git a/internal/monitoring/monitor.go b/internal/monitoring/monitor.go
index 486079b4d..b37b64020 100644
--- a/internal/monitoring/monitor.go
+++ b/internal/monitoring/monitor.go
@@ -3163,16 +3163,26 @@ func (m *Monitor) GetState() models.StateSnapshot {
 		}
 		return state
 	}
-	if m.state == nil {
+	// Mock-mode transitions replace the state under m.mu. Capture the fully
+	// initialized pointer under the same lock, then let State protect its own
+	// snapshot without holding the monitor lock across downstream readers.
+	m.mu.RLock()
+	currentState := m.state
+	m.mu.RUnlock()
+	if currentState == nil {
 		return models.StateSnapshot{}
 	}
 
-	state := m.state.GetSnapshot()
+	state := currentState.GetSnapshot()
 	// Keep externally served alert arrays aligned with the live alert manager
 	// even between explicit sync points, so APIs do not expose stale alert
 	// counts or recently resolved incidents from cached state.
-	state.ActiveAlerts = m.activeAlertsSnapshot()
-	state.RecentlyResolved = m.recentlyResolvedAlertsSnapshot()
+	if m.alertManager != nil {
+		state.ActiveAlerts = m.activeAlertsSnapshot()
+		state.RecentlyResolved = m.recentlyResolvedAlertsSnapshot()
+	}
+	// Without an alert manager, retain alerts from this same captured state;
+	// the fallback helpers would read the replaceable pointer again.
 	// Surface filesystems reported by a unified pulse-agent inside a guest
 	// (for example ZFS mounts that qemu-guest-agent's get-fsinfo cannot see
 	// on PBS, #1438) in the guest overview disk listing.
diff --git a/internal/monitoring/monitor_state_reset_test.go b/internal/monitoring/monitor_state_reset_test.go
new file mode 100644
index 000000000..46fa8399f
--- /dev/null
+++ b/internal/monitoring/monitor_state_reset_test.go
@@ -0,0 +1,82 @@
+package monitoring
+
+import (
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/rcourtman/pulse-go-rewrite/internal/mock"
+	"github.com/rcourtman/pulse-go-rewrite/internal/models"
+)
+
+// Exercise the production reset boundary without Start or its background
+// goroutines: shutting down a test differently cannot repair this race.
+func TestGetStateConcurrentReset(t *testing.T) {
+	previous := mock.IsMockEnabled()
+	mustSetMockEnabled(t, false)
+	defer mustSetMockEnabled(t, previous)
+
+	startTime := time.Unix(1700000000, 0)
+	m := &Monitor{startTime: startTime}
+	m.mu.Lock()
+	m.resetStateLocked()
+	m.mu.Unlock()
+
+	start := make(chan struct{})
+	var workers sync.WaitGroup
+	workers.Add(2)
+	go func() {
+		defer workers.Done()
+		<-start
+		for i := 0; i < 1000; i++ {
+			m.mu.Lock()
+			m.resetStateLocked()
+			m.mu.Unlock()
+		}
+	}()
+	go func() {
+		defer workers.Done()
+		<-start
+		for i := 0; i < 1000; i++ {
+			snapshot := m.GetState()
+			if snapshot.Stats.StartTime != startTime || snapshot.Stats.Version != "2.0.0-go" {
+				t.Errorf("reader observed partially initialized reset stats: %+v", snapshot.Stats)
+				return
+			}
+		}
+	}()
+	close(start)
+	workers.Wait()
+}
+
+func TestGetStateResetSnapshotIsolation(t *testing.T) {
+	previous := mock.IsMockEnabled()
+	mustSetMockEnabled(t, false)
+	defer mustSetMockEnabled(t, previous)
+
+	m := &Monitor{state: models.NewState(), startTime: time.Unix(1700000000, 0)}
+	m.state.UpdateNodes([]models.Node{{ID: "old-node", Name: "old-node"}})
+	m.state.UpdateActiveAlerts([]models.Alert{{ID: "old-alert"}})
+	m.state.UpdateRecentlyResolved([]models.ResolvedAlert{{Alert: models.Alert{ID: "old-resolved"}}})
+	before := m.GetState()
+	m.mu.Lock()
+	m.resetStateLocked()
+	m.mu.Unlock()
+	after := m.GetState()
+	if len(before.Nodes) != 1 || before.Nodes[0].ID != "old-node" {
+		t.Fatal("reset changed the previously returned snapshot")
+	}
+	if len(before.ActiveAlerts) != 1 || before.ActiveAlerts[0].ID != "old-alert" ||
+		len(before.RecentlyResolved) != 1 || before.RecentlyResolved[0].ID != "old-resolved" {
+		t.Fatal("snapshot lost state-backed alerts without an alert manager")
+	}
+	if len(after.ActiveAlerts) != 0 || len(after.RecentlyResolved) != 0 {
+		t.Fatal("reset retained stale state-backed alerts")
+	}
+	if len(after.Nodes) != 0 || after.Stats.StartTime != m.startTime || after.Stats.Version != "2.0.0-go" {
+		t.Fatalf("reset did not expose an initialized empty state: %+v", after)
+	}
+	if snapshot := (&Monitor{}).GetState(); len(snapshot.Nodes) != 0 {
+		t.Fatal("nil state must return an empty snapshot")
+	}
+}