reasoning: prevent unsupported comparison decomposition

tests/graph/decomposition-quality.test.js

@@ -225,7 +225,7 @@ describe("decomposition stopping conditions", () => {
     );
   });
 
-  it("stops once a directly answerable child is selected", () => {
+  it("does not manufacture comparison children for a generic explanatory parent", () => {
     const { parent, graph } = makeParentGraph({
       centralStatement: "Traffic increased, but sales stayed flat.",
       parentLabel:
@@ -259,15 +259,82 @@ describe("decomposition stopping conditions", () => {
 
     expect(result.success).toBe(true);
     expect(result.decompositionAttempted).toBe(true);
-    expect(result.decompositionAccepted).toBe(true);
-    expect(result.selectedQuestion).toMatchObject({
-      nodeId: expect.any(String),
-      question:
-        "What evidence would clarify how the two observations were measured?",
-    });
-    expect(result.selectedChildNodeId).toBe(result.selectedQuestion?.nodeId);
+    expect(result.decompositionAccepted).toBe(false);
+    expect(result.childUnknownCount).toBe(0);
+    expect(
+      result.updatedSituationGraph.nodes.some(
+        (node) => node.parentId === parent.id,
+      ),
+    ).toBe(false);
+    expect(
+      result.updatedSituationGraph.nodes.some(
+        (node) => node.label === "How the two observations were measured",
+      ),
+    ).toBe(false);
+    expect(
+      result.updatedSituationGraph.nodes.some(
+        (node) =>
+          node.label ===
+          "Whether the two observations reflect different timing",
+      ),
+    ).toBe(false);
     expect(result.decompositionStoppedReason).toBe(
-      "Selected child is atomic and directly answerable.",
+      "Decomposition stopped because no meaning-preserving child family was justified for this parent.",
+    );
+    expect(result.selectedQuestion?.question || "").not.toContain(
+      "two observations",
+    );
+  });
+
+  it("still decomposes a genuine comparison/measurement parent into valid comparison children", () => {
+    const { graph } = makeParentGraph({
+      centralStatement:
+        "Revenue increased by 18%, but cash in the bank fell over the same period.",
+      parentLabel: "Timing or measurement basis",
+      parentDescription:
+        "Need evidence about whether a timing or measurement-basis difference could explain the observations, because that would change how they should be interpreted.",
+      observations: [
+        makeNode({
+          id: "n-revenue",
+          label: "Revenue increased by 18%.",
+          description: "Revenue increased by 18%.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+        makeNode({
+          id: "n-cash",
+          label: "Cash in the bank decreased over the same period.",
+          description: "Cash in the bank decreased over the same period.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+        }),
+      ],
+    });
+
+    const result = applyValidatedProposal({
+      situationGraph: graph,
+      proposal: makeMeaningfulNoOpProposal(),
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.decompositionPerformed).toBe(true);
+    expect(result.childUnknownCount).toBe(2);
+    expect(
+      result.updatedSituationGraph.nodes.some(
+        (node) => node.label === "How the two observations were measured",
+      ),
+    ).toBe(true);
+    expect(
+      result.updatedSituationGraph.nodes.some(
+        (node) =>
+          node.label ===
+          "Whether the two observations reflect different timing",
+      ),
+    ).toBe(true);
+    expect(result.selectedQuestion?.question).toBe(
+      "What evidence would clarify how the two observations were measured?",
     );
   });