diff --git a/internal/hierarchy/hierarchy.go b/internal/hierarchy/hierarchy.go
index 02ba6d8..b19b88e 100644
--- a/internal/hierarchy/hierarchy.go
+++ b/internal/hierarchy/hierarchy.go
@@ -667,6 +667,31 @@ func (t *Tree) Transitional() bool {
 	return false
 }
 
+// ScreenName names the route this tree shows: the driver-set screen when the
+// platform reports one (web), otherwise the resource id ending in "Screen" that
+// marks the route composable. A tree carrying two different route ids is a
+// cross-fade in flight and names no screen, which is the same reading
+// Transitional gives it.
+func (t *Tree) ScreenName() string {
+	if t == nil || len(t.Elements) == 0 {
+		return ""
+	}
+	if screen := t.Elements[0].Screen; screen != "" {
+		return screen
+	}
+	name := ""
+	for _, element := range t.Elements {
+		if !strings.HasSuffix(element.ResourceID, "Screen") {
+			continue
+		}
+		if name != "" && name != element.ResourceID {
+			return ""
+		}
+		name = element.ResourceID
+	}
+	return name
+}
+
 // Find returns the first element matching the selector, or nil.
 func (t *Tree) Find(selector string) *Element {
 	node := t.FindNode(selector)
diff --git a/internal/hierarchy/hierarchy_test.go b/internal/hierarchy/hierarchy_test.go
index 02e6bd5..d742bfc 100644
--- a/internal/hierarchy/hierarchy_test.go
+++ b/internal/hierarchy/hierarchy_test.go
@@ -1821,3 +1821,57 @@ func TestTagMatchesTheElementItNames(t *testing.T) {
 		})
 	}
 }
+
+func TestScreenNameNamesTheRouteTheTreeShows(t *testing.T) {
+	cases := []struct {
+		name string
+		tree string
+		want string
+	}{
+		{
+			"driver-set screen",
+			`{"attributes": {"bounds": "[0,0,10,10]", "sanderling-screen": "/ledger"}, "children": []}`,
+			"/ledger",
+		},
+		{
+			"route marker",
+			`{"attributes": {"bounds": "[0,0,10,10]"}, "children": [
+				{"attributes": {"resource-id": "HomeScreen", "bounds": "[0,0,10,10]"}, "children": []}
+			]}`,
+			"HomeScreen",
+		},
+		{
+			"route marker repeated by a nested node",
+			`{"attributes": {"bounds": "[0,0,10,10]"}, "children": [
+				{"attributes": {"resource-id": "HomeScreen", "bounds": "[0,0,10,10]"}, "children": [
+					{"attributes": {"resource-id": "HomeScreen", "bounds": "[0,0,10,5]"}, "children": []}
+				]}
+			]}`,
+			"HomeScreen",
+		},
+		{
+			"cross-fade names no screen",
+			`{"attributes": {"bounds": "[0,0,10,10]"}, "children": [
+				{"attributes": {"resource-id": "HomeScreen", "bounds": "[0,0,10,10]"}, "children": []},
+				{"attributes": {"resource-id": "LedgerScreen", "bounds": "[0,0,10,10]"}, "children": []}
+			]}`,
+			"",
+		},
+		{
+			"no marker at all",
+			`{"attributes": {"bounds": "[0,0,10,10]"}, "children": []}`,
+			"",
+		},
+	}
+	for _, testCase := range cases {
+		t.Run(testCase.name, func(t *testing.T) {
+			tree, err := Parse(testCase.tree)
+			if err != nil {
+				t.Fatalf("Parse: %v", err)
+			}
+			if got := tree.ScreenName(); got != testCase.want {
+				t.Errorf("ScreenName = %q, want %q", got, testCase.want)
+			}
+		})
+	}
+}