diff --git a/internal/alerts/guest_tags_test.go b/internal/alerts/guest_tags_test.go
new file mode 100644
index 000000000..a425641df
--- /dev/null
+++ b/internal/alerts/guest_tags_test.go
@@ -0,0 +1,173 @@
+package alerts
+
+import (
+	"testing"
+
+	"github.com/rcourtman/pulse-go-rewrite/internal/models"
+)
+
+func TestIgnoredGuestPrefixesSkipsAlerts(t *testing.T) {
+	m := newTestManager(t)
+	m.ClearActiveAlerts()
+
+	m.mu.Lock()
+	m.config.IgnoredGuestPrefixes = []string{"ignore-", "test-"}
+	m.config.GuestDefaults = ThresholdConfig{CPU: &HysteresisThreshold{Trigger: 80, Clear: 70}}
+	m.config.TimeThreshold = 0
+	m.config.TimeThresholds = map[string]int{}
+	m.mu.Unlock()
+
+	ignoredGuest := models.VM{
+		ID:     "qemu/100",
+		Name:   "ignore-vm1",
+		Status: "running",
+		CPU:    0.9, // 90%
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	monitoredGuest := models.VM{
+		ID:     "qemu/101",
+		Name:   "prod-vm1",
+		Status: "running",
+		CPU:    0.9, // 90%
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	// Check ignored guest
+	m.CheckGuest(ignoredGuest, "node1")
+	if len(m.activeAlerts) != 0 {
+		t.Errorf("expected 0 active alerts for ignored prefix, got %d", len(m.activeAlerts))
+	}
+
+	// Check monitored guest
+	m.CheckGuest(monitoredGuest, "node1")
+	if len(m.activeAlerts) != 1 {
+		t.Errorf("expected 1 active alert for monitored guest, got %d", len(m.activeAlerts))
+	}
+}
+
+func TestGuestTagBlacklistSkipsAlerts(t *testing.T) {
+	m := newTestManager(t)
+	m.ClearActiveAlerts()
+
+	m.mu.Lock()
+	m.config.GuestTagBlacklist = []string{"maintenance", "backup"}
+	m.config.GuestDefaults = ThresholdConfig{CPU: &HysteresisThreshold{Trigger: 80, Clear: 70}}
+	m.config.TimeThreshold = 0
+	m.config.TimeThresholds = map[string]int{}
+	m.mu.Unlock()
+
+	blacklistedGuest := models.VM{
+		ID:     "qemu/100",
+		Name:   "vm1",
+		Status: "running",
+		Tags:   []string{"production", "maintenance"}, // Has blacklisted tag
+		CPU:    0.9,
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	normalGuest := models.VM{
+		ID:     "qemu/101",
+		Name:   "vm2",
+		Status: "running",
+		Tags:   []string{"production"},
+		CPU:    0.9,
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	m.CheckGuest(blacklistedGuest, "node1")
+	if len(m.activeAlerts) != 0 {
+		t.Errorf("expected 0 active alerts for blacklisted guest, got %d", len(m.activeAlerts))
+	}
+
+	m.CheckGuest(normalGuest, "node1")
+	if len(m.activeAlerts) != 1 {
+		t.Errorf("expected 1 active alert for normal guest, got %d", len(m.activeAlerts))
+	}
+}
+
+func TestGuestTagWhitelistSkipsAlertsIfTagMissing(t *testing.T) {
+	m := newTestManager(t)
+	m.ClearActiveAlerts()
+
+	m.mu.Lock()
+	m.config.GuestTagWhitelist = []string{"monitor-me", "production"}
+	m.config.GuestDefaults = ThresholdConfig{CPU: &HysteresisThreshold{Trigger: 80, Clear: 70}}
+	m.config.TimeThreshold = 0
+	m.config.TimeThresholds = map[string]int{}
+	m.mu.Unlock()
+
+	// Guest without whitelisted tag
+	unwatchedGuest := models.VM{
+		ID:     "qemu/100",
+		Name:   "vm1",
+		Status: "running",
+		Tags:   []string{"staging"},
+		CPU:    0.9,
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	// Guest with whitelisted tag
+	watchedGuest := models.VM{
+		ID:     "qemu/101",
+		Name:   "vm2",
+		Status: "running",
+		Tags:   []string{"staging", "monitor-me"},
+		CPU:    0.9,
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	m.CheckGuest(unwatchedGuest, "node1")
+	if len(m.activeAlerts) != 0 {
+		t.Errorf("expected 0 active alerts for guest missing whitelist tag, got %d", len(m.activeAlerts))
+	}
+
+	m.CheckGuest(watchedGuest, "node1")
+	if len(m.activeAlerts) != 1 {
+		t.Errorf("expected 1 active alert for whitelisted guest, got %d", len(m.activeAlerts))
+	}
+}
+
+func TestGuestIgnoredPrefixClearsActiveAlerts(t *testing.T) {
+	m := newTestManager(t)
+	m.ClearActiveAlerts()
+
+	m.mu.Lock()
+	m.config.GuestDefaults = ThresholdConfig{CPU: &HysteresisThreshold{Trigger: 80, Clear: 70}}
+	m.config.TimeThreshold = 0
+	m.config.TimeThresholds = map[string]int{}
+	m.mu.Unlock()
+
+	guest := models.VM{
+		ID:     "qemu/100",
+		Name:   "vm1",
+		Status: "running",
+		CPU:    0.9,
+		Memory: models.Memory{Usage: 50},
+		Disk:   models.Disk{Usage: 50},
+	}
+
+	// 1. Create an alert
+	m.CheckGuest(guest, "node1")
+	if len(m.activeAlerts) != 1 {
+		t.Fatalf("setup failed: expected 1 alert, got %d", len(m.activeAlerts))
+	}
+
+	// 2. Ignore the prefix
+	m.mu.Lock()
+	m.config.IgnoredGuestPrefixes = []string{"vm"}
+	m.mu.Unlock()
+
+	// 3. Check guest again
+	m.CheckGuest(guest, "node1")
+
+	if len(m.activeAlerts) != 0 {
+		t.Errorf("expected 0 alerts after adding ignored prefix, got %d", len(m.activeAlerts))
+	}
+}