feat: back next questions with explicit graph unknowns

tests/graph/orchestrator.test.js

@@ -1046,7 +1046,12 @@ describe("lib/graph/orchestrator startCase", () => {
       relationshipStatus: "potentially_related",
       relationshipAssessed: true,
       resolvedReasoningNodeIds: ["reasoning:comparability"],
+      emergentReasoningNodeCreated: true,
     });
+    expect(result.diagnostics.emergentReasoningNodeId).toBeTruthy();
+    expect(result.diagnostics.emergentReasoningNodeReason).toContain(
+      "backed by the graph",
+    );
     expect(result.diagnostics.reasoningStagesBefore).toEqual([
       {
         stage: "comparability",
@@ -1074,6 +1079,7 @@ describe("lib/graph/orchestrator startCase", () => {
           "The observations concern connected business signals but do not establish a direct contradiction or cause.",
       },
     ]);
+    expect(result.selectedQuestion?.nodeId).toBe(result.newActiveUnknownNodeId);
     expect(result.selectedQuestion?.question).toMatch(
       /^What changed during that period that could help explain why /,
     );