diff --git a/tests/domain/starter-environment-assets.test.ts b/tests/domain/starter-environment-assets.test.ts
new file mode 100644
index 00000000..f2fd5246
--- /dev/null
+++ b/tests/domain/starter-environment-assets.test.ts
@@ -0,0 +1,60 @@
+import { describe, expect, it } from "vitest";
+
+import { createEditorStore } from "../../src/app/editor-store";
+import {
+  STARTER_DAY_ENVIRONMENT_ASSET_ID,
+  STARTER_NIGHT_ENVIRONMENT_ASSET_ID
+} from "../../src/assets/starter-environment-assets";
+import { createEmptyProjectDocument } from "../../src/document/scene-document";
+import { DEFAULT_NIGHT_IMAGE_ENVIRONMENT_INTENSITY } from "../../src/document/world-settings";
+
+describe("starter environment assets", () => {
+  it("seeds starter environments and defaults untouched day and night backgrounds", () => {
+    const store = createEditorStore();
+    const projectDocument = store.getState().projectDocument;
+    const world = store.getState().document.world;
+
+    expect(projectDocument.assets[STARTER_DAY_ENVIRONMENT_ASSET_ID]).toBeDefined();
+    expect(projectDocument.assets[STARTER_NIGHT_ENVIRONMENT_ASSET_ID]).toBeDefined();
+    expect(world.background).toEqual({
+      mode: "image",
+      assetId: STARTER_DAY_ENVIRONMENT_ASSET_ID,
+      environmentIntensity: 0.85
+    });
+    expect(world.timeOfDay.night.background).toEqual({
+      mode: "image",
+      assetId: STARTER_NIGHT_ENVIRONMENT_ASSET_ID,
+      environmentIntensity: DEFAULT_NIGHT_IMAGE_ENVIRONMENT_INTENSITY
+    });
+  });
+
+  it("does not overwrite authored scene backgrounds when adding starter environments", () => {
+    const projectDocument = createEmptyProjectDocument();
+    const activeScene = projectDocument.scenes[projectDocument.activeSceneId];
+
+    activeScene.world.background = {
+      mode: "solid",
+      colorHex: "#123456"
+    };
+    activeScene.world.timeOfDay.night.background = {
+      mode: "solid",
+      colorHex: "#05070a"
+    };
+
+    const store = createEditorStore({
+      initialProjectDocument: projectDocument
+    });
+    const world = store.getState().document.world;
+
+    expect(store.getState().projectDocument.assets[STARTER_DAY_ENVIRONMENT_ASSET_ID]).toBeDefined();
+    expect(store.getState().projectDocument.assets[STARTER_NIGHT_ENVIRONMENT_ASSET_ID]).toBeDefined();
+    expect(world.background).toEqual({
+      mode: "solid",
+      colorHex: "#123456"
+    });
+    expect(world.timeOfDay.night.background).toEqual({
+      mode: "solid",
+      colorHex: "#05070a"
+    });
+  });
+});