feat: decompose composite unknowns before questioning

tests/graph/orchestrator.test.js

@@ -1047,8 +1047,13 @@ describe("lib/graph/orchestrator startCase", () => {
       relationshipAssessed: true,
       resolvedReasoningNodeIds: ["reasoning:comparability"],
       emergentReasoningNodeCreated: true,
+      atomicityAssessment: "composite",
+      decompositionPerformed: true,
+      childUnknownCount: 5,
     });
     expect(result.diagnostics.emergentReasoningNodeId).toBeTruthy();
+    expect(result.diagnostics.childNodeIds).toHaveLength(5);
+    expect(result.diagnostics.atomicityReason).toContain("Decomposed");
     expect(result.diagnostics.emergentReasoningNodeReason).toContain(
       "backed by the graph",
     );
@@ -1080,8 +1085,8 @@ describe("lib/graph/orchestrator startCase", () => {
       },
     ]);
     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).toBe(
+      "What evidence would clarify timing or measurement basis?",
     );
     expect(result.selectedQuestion?.question.toLowerCase()).not.toMatch(
       /same basis|dso|receivables|debtor days|working capital/,