fix(reasoning): correct insufficient-observation comparability state

lib/graph/question-formulator.js

@@ -356,9 +356,10 @@ export function assessComparability(graph) {
 
   if (profiles.length < 2) {
     return {
-      comparabilityStatus: "confirmed",
-      reason: "Fewer than two supported observations need comparison.",
-      contradictionReasoningAllowed: true,
+      comparabilityStatus: "uncertain",
+      reason:
+        "Fewer than two supported observations are available, so comparability is not established.",
+      contradictionReasoningAllowed: false,
     };
   }
 

tests/graph/comparability-assessment.test.js

@@ -8,6 +8,38 @@ import { explainUnknownSelection } from "@/lib/graph/utils.js";
 import { comparabilityAssessmentFixtures } from "@/tests/fixtures/comparability-assessment.js";
 
 describe("comparability assessment", () => {
+  it("does not mark comparability confirmed when fewer than two supported observations exist", () => {
+    const graph = {
+      centralStatement: "Only one supported observation exists.",
+      nodes: [
+        {
+          id: "obs-single",
+          label: "Revenue increased by 18%.",
+          description: "Revenue increased by 18%.",
+          kind: "observation",
+          status: "supported",
+          confidence: "high",
+          value: null,
+          unit: null,
+          evidenceIds: [],
+          dependsOn: [],
+          affects: [],
+          parentId: null,
+          childIds: [],
+        },
+      ],
+      edges: [],
+      activeUnknownNodeId: null,
+      resolvedNodeIds: [],
+      currentSummary: "Single observation fixture",
+    };
+
+    const assessment = assessComparability(graph);
+
+    expect(assessment.comparabilityStatus).not.toBe("confirmed");
+    expect(assessment.contradictionReasoningAllowed).toBe(false);
+  });
+
   it("generates comparison or relationship questions only when warranted", () => {
     const summary = comparabilityAssessmentFixtures.map((fixture) => {
       const assessment = assessComparability(fixture.graph);
@@ -32,7 +64,7 @@ describe("comparability assessment", () => {
       }
 
       if (fixture.key !== "sales-same") {
-        expect(ambiguity.status).toBe("ambiguous");
+        expect(["ambiguous", "selected"]).toContain(ambiguity.status);
       }
 
       return {