diff --git a/backend/internal/web/ui/ui_test.go b/backend/internal/web/ui/ui_test.go
index 85d8465..26b81d2 100644
--- a/backend/internal/web/ui/ui_test.go
+++ b/backend/internal/web/ui/ui_test.go
@@ -130,3 +130,64 @@ func TestNormalizers_ZeroValueDefaults(t *testing.T) {
 		t.Errorf("NormalizedBadgeVariant(\"\") = %q; want %q", got, BadgeVariantInfo)
 	}
 }
+
+// Phase 13 Plan 01 — new enum and class function tests (TDD RED)
+
+func TestButtonVariantGhost_Normalizer(t *testing.T) {
+	got := NormalizedButtonVariant(ButtonVariantGhost)
+	if got != ButtonVariantGhost {
+		t.Errorf("NormalizedButtonVariant(ButtonVariantGhost) = %q; want %q", got, ButtonVariantGhost)
+	}
+}
+
+func TestButtonClass_GhostVariant(t *testing.T) {
+	got := ButtonClass(ButtonVariantGhost, ButtonToneSolid, SizeMD)
+	if !strings.Contains(got, "ui-button-ghost") {
+		t.Errorf("ButtonClass(Ghost, Solid, MD) = %q; want to contain \"ui-button-ghost\"", got)
+	}
+}
+
+func TestBadgeVariantPrimary_Normalizer(t *testing.T) {
+	got := NormalizedBadgeVariant(BadgeVariantPrimary)
+	if got != BadgeVariantPrimary {
+		t.Errorf("NormalizedBadgeVariant(BadgeVariantPrimary) = %q; want %q", got, BadgeVariantPrimary)
+	}
+}
+
+func TestBadgeClass_PrimaryVariant(t *testing.T) {
+	got := BadgeClass(BadgeVariantPrimary)
+	want := "ui-badge ui-badge-primary"
+	if got != want {
+		t.Errorf("BadgeClass(BadgeVariantPrimary) = %q; want %q", got, want)
+	}
+}
+
+func TestIconButtonClass_GhostNeutral(t *testing.T) {
+	got := IconButtonClass(IconButtonVariantNeutral, IconButtonToneGhost)
+	if !strings.Contains(got, "borderless-icon-button") {
+		t.Errorf("IconButtonClass(Neutral, Ghost) = %q; want to contain \"borderless-icon-button\"", got)
+	}
+}
+
+func TestIconButtonClass_SolidNeutral(t *testing.T) {
+	got := IconButtonClass(IconButtonVariantNeutral, IconButtonToneSolid)
+	if !strings.Contains(got, "ui-icon-button-solid") {
+		t.Errorf("IconButtonClass(Neutral, Solid) = %q; want to contain \"ui-icon-button-solid\"", got)
+	}
+}
+
+func TestSpaceXClass_MD(t *testing.T) {
+	got := SpaceXClass(SpacingStepMD)
+	want := "ui-space-x ui-space-x-md"
+	if got != want {
+		t.Errorf("SpaceXClass(SpacingStepMD) = %q; want %q", got, want)
+	}
+}
+
+func TestSpaceYClass_LG(t *testing.T) {
+	got := SpaceYClass(SpacingStepLG)
+	want := "ui-space-y ui-space-y-lg"
+	if got != want {
+		t.Errorf("SpaceYClass(SpacingStepLG) = %q; want %q", got, want)
+	}
+}