diff --git a/tests/experimental/rto-explicit-node-formulation.test.js b/tests/experimental/rto-explicit-node-formulation.test.js
new file mode 100644
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+++ b/tests/experimental/rto-explicit-node-formulation.test.js
@@ -0,0 +1,43 @@
+import { describe, expect, it } from "vitest";
+
+import fixture from "@/tests/fixtures/live-product-launch-update-response.json";
+import { formulateQuestion } from "@/lib/graph/question-formulator.js";
+
+describe("RTO.A5 explicit-node formulation apparatus", () => {
+  it("formulates directly for nxmeiab without selector invocation or graph mutation", () => {
+    const graph = structuredClone(fixture.updatedSituationGraph);
+    const graphBefore = structuredClone(graph);
+    const capturedSelectedQuestionNodeIdBefore = fixture.selectedQuestion.nodeId;
+    const activeUnknownNodeIdBefore = graph.activeUnknownNodeId ?? null;
+    const resolvedNodeIdsBefore = structuredClone(graph.resolvedNodeIds || []);
+
+    const target = graph.nodes.find((node) => node.id === "nxmeiab");
+
+    expect(target).toBeTruthy();
+    expect(target?.kind).toBe("unknown");
+    expect(target?.status).not.toBe("resolved");
+
+    const result = formulateQuestion({
+      node: target,
+      graph,
+      context: {
+        selectionState: {
+          status: "selected",
+          nodeId: "nxmeiab",
+        },
+      },
+    });
+
+    expect(result).toBeTruthy();
+    expect(typeof result.question).toBe("string");
+    expect(result.question.length).toBeGreaterThan(0);
+    expect(result.question.toLowerCase()).toMatch(
+      /competitor|competitors|similar products|release/,
+    );
+
+    expect(fixture.selectedQuestion.nodeId).toBe(capturedSelectedQuestionNodeIdBefore);
+    expect(graph.activeUnknownNodeId ?? null).toBe(activeUnknownNodeIdBefore);
+    expect(graph.resolvedNodeIds || []).toEqual(resolvedNodeIdsBefore);
+    expect(graph).toEqual(graphBefore);
+  });
+});
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