feat: add physically explicit narrowband MUSIC

tests/integration/array-builder-ui.test.js

@@ -613,6 +613,9 @@ test("Array Builder가 preset·직접 편집·검증·표준 JSON round trip을
         () => cameraDocument.documentElement.dataset.appReady === "true",
         "Camera handoff initialization",
       );
+      const defaultCameraExperiment = await cameraWindow
+        .fetch("/assets/sample-scenes/single-tone.experiment.json")
+        .then((response) => response.json());
       const handoffFile = new cameraWindow.File(
         [JSON.stringify(editedExport)],
         "builder-handoff.array.json",
@@ -642,8 +645,12 @@ test("Array Builder가 preset·직접 편집·검증·표준 JSON round trip을
       );
       assertEqual(
         cameraExperiment.arrayId,
-        editedExport.id,
-        "Camera rebinds Experiment to the Builder Array ID",
+        defaultCameraExperiment.arrayId,
+        "Camera preserves the Experiment Array provenance label",
+      );
+      assert(
+        cameraExperiment.arrayId !== editedExport.id,
+        "opening a Builder Array does not rewrite Experiment provenance",
       );
     } finally {
       cameraWindow.URL.createObjectURL = originalCameraCreate;