diff --git a/internal/unifiedresources/resolved_host_set_test.go b/internal/unifiedresources/resolved_host_set_test.go
index d018608dca..a6b3292a06 100644
--- a/internal/unifiedresources/resolved_host_set_test.go
+++ b/internal/unifiedresources/resolved_host_set_test.go
@@ -691,3 +691,27 @@ func TestBroadcastGroupingMatchesPreviousAlgorithm(t *testing.T) {
 		}
 	}
 }
+
+func TestTopLevelOwnerIndexPreservesAmbiguityInMonitoredCountAndAdmission(t *testing.T) {
+	for _, targetCount := range []int{1, 2} {
+		t.Run(fmt.Sprintf("%d_targets", targetCount), func(t *testing.T) {
+			resources := []Resource{
+				topLevelTestProxmoxNode("platform", "tower.lab", "pve-source", "https://tower.lab:8006"),
+				topLevelTestTrueNAS("nas", "tower.lab"),
+			}
+			registry := NewRegistry(nil)
+			registry.IngestResources(resources[:targetCount])
+			if got := MonitoredSystemCount(registry); got != targetCount {
+				t.Fatalf("counted inventory changed: %d/%d", got, targetCount)
+			}
+			projection := ProjectMonitoredSystemCandidate(registry, MonitoredSystemCandidate{Source: SourceAgent, Type: ResourceTypeAgent, Hostname: "tower", AgentID: "new-agent"})
+			additional := targetCount - 1
+			if projection.CurrentCount != targetCount || projection.AdditionalCount != additional || projection.ProjectedCount != targetCount+additional {
+				t.Fatalf("unique attachment/ambiguous admission changed: %+v", projection)
+			}
+			if got := len(registry.List()); got != targetCount {
+				t.Fatalf("read-only projection changed stored inventory: %d/%d", got, targetCount)
+			}
+		})
+	}
+}
diff --git a/internal/unifiedresources/top_level_owner_index_test.go b/internal/unifiedresources/top_level_owner_index_test.go
index 98137bcf2e..81a9b60a67 100644
--- a/internal/unifiedresources/top_level_owner_index_test.go
+++ b/internal/unifiedresources/top_level_owner_index_test.go
@@ -310,7 +310,7 @@ func CheckTopLevelOwnerIndexResourcesForTest(t testing.TB, resources []Resource)
 	t.Logf("connected grouping retains %d resources in %d groups with byte-equal records", members, got.Count())
 }
 
-func BenchmarkTopLevelOwnerIndexResourcesForTest(b *testing.B, resources []Resource) {
+func RunTopLevelOwnerIndexBenchmarkForTest(b *testing.B, resources []Resource) {
 	for _, method := range []struct {
 		name    string
 		resolve func([]Resource) TopLevelSystemResolver
diff --git a/internal/unifiedresources/top_level_owner_integration_test.go b/internal/unifiedresources/top_level_owner_integration_test.go
index f8ecaac7da..69fea88963 100644
--- a/internal/unifiedresources/top_level_owner_integration_test.go
+++ b/internal/unifiedresources/top_level_owner_integration_test.go
@@ -58,5 +58,5 @@ func TestTopLevelOwnerIndexConnectedDemo(t *testing.T) {
 
 func BenchmarkTopLevelOwnerIndexConnectedDemo(b *testing.B) {
 	resources := connectedOwnerIndexResources(b)
-	unified.BenchmarkTopLevelOwnerIndexResourcesForTest(b, resources)
+	unified.RunTopLevelOwnerIndexBenchmarkForTest(b, resources)
 }
diff --git a/internal/unifiedresources/top_level_systems.go b/internal/unifiedresources/top_level_systems.go
index ed9dc70805..bfb8d87b6f 100644
--- a/internal/unifiedresources/top_level_systems.go
+++ b/internal/unifiedresources/top_level_systems.go
@@ -433,9 +433,6 @@ func buildTopLevelSystemFallbackIndex(groups map[int]topLevelSystemResolvedGroup
 		return roots[i] < roots[j]
 	})
 	add := func(owners map[string][]int, key string, root int) {
-		if key == "" {
-			return
-		}
 		bucket := owners[key]
 		// All aliases of one root are added together, so a last-entry check
 		// deduplicates its comparable/short forms without a per-key set.
@@ -448,9 +445,11 @@ func buildTopLevelSystemFallbackIndex(groups map[int]topLevelSystemResolvedGroup
 		for host := range group.exactHosts {
 			add(index.hosts, host, root)
 			comparable := normalizeComparableHostname(host)
-			add(index.hostForms, comparable, root)
 			if comparable != "" {
-				add(index.hostForms, NormalizeHostname(comparable), root)
+				add(index.hostForms, comparable, root)
+				if short := NormalizeHostname(comparable); short != "" {
+					add(index.hostForms, short, root)
+				}
 			}
 		}
 		for ip := range group.exactIPs {