feat: decompose composite unknowns before questioning

tests/graph/apply-proposal.test.js

@@ -1146,10 +1146,10 @@ describe("applyValidatedProposal", () => {
       comparabilityUnknownId,
     ]);
     expect(result.selectedQuestion?.nodeId).toBe(result.newActiveUnknownNodeId);
-    expect(result.selectedQuestion?.question).toMatch(
-      /^What changed during that period that could help explain why /,
-    );
-    expect(result.selectedQuestion?.question).not.toContain("same basis");
+    expect(result.selectedQuestion).toMatchObject({
+      nodeId: result.newActiveUnknownNodeId,
+      question: "What evidence would clarify timing or measurement basis?",
+    });
     expect(result.selectedQuestion?.question.toLowerCase()).not.toMatch(
       /dso|debtor days|receivables turnover|working capital|receivables/,
     );
@@ -1224,12 +1224,97 @@ describe("applyValidatedProposal", () => {
     expect(result.success).toBe(true);
     expect(result.emergentReasoningNodeCreated).toBe(false);
     expect(result.emergentReasoningNodeId).toBe("n-existing-explanation");
-    expect(result.newActiveUnknownNodeId).toBe("n-existing-explanation");
-    expect(result.selectedQuestion?.nodeId).toBe("n-existing-explanation");
+    expect(result.newActiveUnknownNodeId).not.toBe("n-existing-explanation");
+    expect(result.selectedQuestion?.nodeId).not.toBe("n-existing-explanation");
+    expect(result.selectedQuestion?.question).toBe(
+      "What evidence would clarify timing or measurement basis?",
+    );
     expect(
       result.updatedSituationGraph.nodes.filter(
         (node) => node.label === graph.nodes.at(-1).label,
       ),
     ).toHaveLength(1);
   });
+
+  it("decomposes a composite selected unknown before asking the next question", () => {
+    const { graph, proposal } = makeComparabilityUpdateFixture();
+
+    const result = applyValidatedProposal({
+      situationGraph: graph,
+      proposal,
+      previousQuestion:
+        "Were these figures measured on the same basis and at the same scale?",
+      answer:
+        "Yes. Both figures cover the same accounting period and are taken from the same management accounts.",
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.atomicityAssessment).toBe("composite");
+    expect(result.decompositionPerformed).toBe(true);
+    expect(result.childUnknownCount).toBe(5);
+    expect(result.childNodeIds).toHaveLength(5);
+    expect(result.atomicityReason).toContain("Decomposed");
+    expect(result.selectedQuestion?.nodeId).toBe(result.newActiveUnknownNodeId);
+    expect(result.selectedQuestion?.nodeId).not.toBe(
+      result.emergentReasoningNodeId,
+    );
+    expect(result.selectedQuestion?.question.toLowerCase()).not.toMatch(
+      /dso|working capital|receivables|capex/,
+    );
+
+    const parentNode = result.updatedSituationGraph.nodes.find(
+      (node) => node.id === result.emergentReasoningNodeId,
+    );
+    expect(parentNode?.status).toBe("unknown");
+
+    const childNodes = result.updatedSituationGraph.nodes.filter((node) =>
+      result.childNodeIds.includes(node.id),
+    );
+    expect(childNodes).toHaveLength(5);
+    expect(childNodes.every((node) => node.parentId === parentNode.id)).toBe(
+      true,
+    );
+    expect(
+      result.updatedSituationGraph.edges.filter(
+        (edge) =>
+          result.childNodeIds.includes(edge.fromNodeId) &&
+          edge.toNodeId === parentNode.id &&
+          edge.relationship === "depends_on",
+      ),
+    ).toHaveLength(5);
+  });
+
+  it("reuses existing decomposition children instead of duplicating them", () => {
+    const { graph, proposal } = makeComparabilityUpdateFixture();
+
+    const firstResult = applyValidatedProposal({
+      situationGraph: graph,
+      proposal,
+      previousQuestion:
+        "Were these figures measured on the same basis and at the same scale?",
+      answer:
+        "Yes. Both figures cover the same accounting period and are taken from the same management accounts.",
+    });
+
+    expect(firstResult.success).toBe(true);
+
+    const secondResult = applyValidatedProposal({
+      situationGraph: graph,
+      proposal,
+      previousQuestion:
+        "Were these figures measured on the same basis and at the same scale?",
+      answer:
+        "Yes. Both figures cover the same accounting period and are taken from the same management accounts.",
+    });
+
+    expect(secondResult.success).toBe(true);
+    expect(secondResult.atomicityAssessment).toBe("composite");
+    const uniqueChildIds = new Set(firstResult.childNodeIds);
+    expect(uniqueChildIds.size).toBe(firstResult.childNodeIds.length);
+    expect(
+      secondResult.updatedSituationGraph.nodes.filter((node) =>
+        firstResult.childNodeIds.includes(node.id),
+      ),
+    ).toHaveLength(firstResult.childNodeIds.length);
+  });
 });