diff --git a/tests/unit/terrain-foundation.integration.test.tsx b/tests/unit/terrain-foundation.integration.test.tsx
new file mode 100644
index 00000000..035a7761
--- /dev/null
+++ b/tests/unit/terrain-foundation.integration.test.tsx
@@ -0,0 +1,135 @@
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
+
+const { MockViewportHost, viewportHostInstances } = vi.hoisted(() => {
+  const viewportHostInstances: Array<{
+    mount: ReturnType<typeof vi.fn>;
+    dispose: ReturnType<typeof vi.fn>;
+    updateWorld: ReturnType<typeof vi.fn>;
+    updateSimulation: ReturnType<typeof vi.fn>;
+    updateAssets: ReturnType<typeof vi.fn>;
+    updateDocument: ReturnType<typeof vi.fn>;
+    setPanelId: ReturnType<typeof vi.fn>;
+    setRenderEnabled: ReturnType<typeof vi.fn>;
+    setViewMode: ReturnType<typeof vi.fn>;
+    setDisplayMode: ReturnType<typeof vi.fn>;
+    setGridVisible: ReturnType<typeof vi.fn>;
+    setCameraState: ReturnType<typeof vi.fn>;
+    setBrushSelectionChangeHandler: ReturnType<typeof vi.fn>;
+    setCameraStateChangeHandler: ReturnType<typeof vi.fn>;
+    setCreationPreviewChangeHandler: ReturnType<typeof vi.fn>;
+    setCreationCommitHandler: ReturnType<typeof vi.fn>;
+    setTransformSessionChangeHandler: ReturnType<typeof vi.fn>;
+    setTransformCommitHandler: ReturnType<typeof vi.fn>;
+    setTransformCancelHandler: ReturnType<typeof vi.fn>;
+    setWhiteboxHoverLabelChangeHandler: ReturnType<typeof vi.fn>;
+    setWhiteboxSelectionMode: ReturnType<typeof vi.fn>;
+    setWhiteboxSnapSettings: ReturnType<typeof vi.fn>;
+    setToolMode: ReturnType<typeof vi.fn>;
+    setCreationPreview: ReturnType<typeof vi.fn>;
+    setTransformSession: ReturnType<typeof vi.fn>;
+    focusSelection: ReturnType<typeof vi.fn>;
+  }> = [];
+
+  class MockViewportHost {
+    mount = vi.fn();
+    dispose = vi.fn();
+    updateWorld = vi.fn();
+    updateSimulation = vi.fn();
+    updateAssets = vi.fn();
+    updateDocument = vi.fn();
+    setPanelId = vi.fn();
+    setRenderEnabled = vi.fn();
+    setViewMode = vi.fn();
+    setDisplayMode = vi.fn();
+    setGridVisible = vi.fn();
+    setCameraState = vi.fn();
+    setBrushSelectionChangeHandler = vi.fn();
+    setCameraStateChangeHandler = vi.fn();
+    setCreationPreviewChangeHandler = vi.fn();
+    setCreationCommitHandler = vi.fn();
+    setTransformSessionChangeHandler = vi.fn();
+    setTransformCommitHandler = vi.fn();
+    setTransformCancelHandler = vi.fn();
+    setWhiteboxHoverLabelChangeHandler = vi.fn();
+    setWhiteboxSelectionMode = vi.fn();
+    setWhiteboxSnapSettings = vi.fn();
+    setToolMode = vi.fn();
+    setCreationPreview = vi.fn();
+    setTransformSession = vi.fn();
+    focusSelection = vi.fn();
+
+    constructor() {
+      viewportHostInstances.push(this);
+    }
+  }
+
+  return {
+    MockViewportHost,
+    viewportHostInstances
+  };
+});
+
+vi.mock("../../src/viewport-three/viewport-host", () => ({
+  ViewportHost: MockViewportHost
+}));
+
+vi.mock("../../src/assets/project-asset-storage", () => ({
+  getBrowserProjectAssetStorageAccess: vi.fn(async () => ({
+    storage: null,
+    diagnostic: null
+  }))
+}));
+
+import { App } from "../../src/app/App";
+import { createEditorStore } from "../../src/app/editor-store";
+
+describe("Terrain foundation", () => {
+  beforeEach(() => {
+    viewportHostInstances.length = 0;
+    vi.spyOn(HTMLCanvasElement.prototype, "getContext").mockImplementation(
+      () => ({}) as never
+    );
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  it("creates terrain from the Add menu and surfaces it through outliner selection and inspector summary", async () => {
+    const store = createEditorStore();
+
+    render(<App store={store} />);
+
+    await waitFor(() => {
+      expect(viewportHostInstances.length).toBeGreaterThan(0);
+    });
+
+    fireEvent.click(screen.getByRole("button", { name: "Add" }));
+    fireEvent.click(await screen.findByTestId("add-menu-terrain"));
+
+    await waitFor(() => {
+      expect(store.getState().selection).toEqual({
+        kind: "terrains",
+        ids: [Object.keys(store.getState().document.terrains)[0]]
+      });
+      expect(Object.keys(store.getState().document.terrains)).toHaveLength(1);
+    });
+
+    const createdTerrain = Object.values(store.getState().document.terrains)[0];
+
+    if (createdTerrain === undefined) {
+      throw new Error("Expected the created terrain to exist.");
+    }
+
+    expect(
+      screen.getByTestId(`outliner-terrain-${createdTerrain.id}`)
+    ).toBeInTheDocument();
+    expect(
+      screen.getByText(
+        "Terrain editing tools land in a later inspector slice. This foundation keeps the authored grid and derived mesh selectable and inspectable."
+      )
+    ).toBeInTheDocument();
+    expect(screen.getByText(/9 x 9 samples/)).toBeInTheDocument();
+  });
+});