diff --git a/tests/unit/viewport-layout.test.ts b/tests/unit/viewport-layout.test.ts
new file mode 100644
index 00000000..5e657f3b
--- /dev/null
+++ b/tests/unit/viewport-layout.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+
+import {
+  createDefaultViewportLayoutState,
+  getViewportDisplayModeLabel,
+  getViewportLayoutModeLabel,
+  getViewportPanelLabel
+} from "../../src/viewport-three/viewport-layout";
+
+describe("viewport layout", () => {
+  it("defaults to a quad-ready panel arrangement with orthographic authoring panes", () => {
+    const layout = createDefaultViewportLayoutState();
+
+    expect(layout.layoutMode).toBe("single");
+    expect(layout.activePanelId).toBe("topLeft");
+    expect(layout.panels.topLeft).toMatchObject({
+      viewMode: "perspective",
+      displayMode: "normal"
+    });
+    expect(layout.panels.topRight).toMatchObject({
+      viewMode: "top",
+      displayMode: "authoring"
+    });
+    expect(layout.panels.bottomLeft).toMatchObject({
+      viewMode: "front",
+      displayMode: "authoring"
+    });
+    expect(layout.panels.bottomRight).toMatchObject({
+      viewMode: "side",
+      displayMode: "authoring"
+    });
+  });
+
+  it("exposes readable labels for the layout and panel chrome", () => {
+    expect(getViewportLayoutModeLabel("single")).toBe("Single View");
+    expect(getViewportLayoutModeLabel("quad")).toBe("4-Panel");
+    expect(getViewportDisplayModeLabel("authoring")).toBe("Authoring");
+    expect(getViewportPanelLabel("topRight")).toBe("Top Right");
+  });
+});