fix(confidence-engine): allow no-op episode reconsideration

tests/graph/apply-proposal.test.js

@@ -706,10 +706,10 @@ describe("applyValidatedProposal", () => {
     expect(graph).toEqual(originalGraph);
   });
 
-  it("rejects a proposal with no meaningful change", () => {
+  it("rejects a proposal with no meaningful change", async () => {
     const { graph } = makeApplicationFixture();
 
-    const result = applyValidatedProposal({
+    const result = await applyValidatedProposal({
       situationGraph: graph,
       proposal: {
         addedNodes: [],
@@ -740,6 +740,68 @@ describe("applyValidatedProposal", () => {
     );
   });
 
+  it("accepts a completed-episode proposal with no additional graph mutation", async () => {
+    const { graph } = makeApplicationFixture();
+    const originalGraph = JSON.parse(JSON.stringify(graph));
+    const noOpProposal = {
+      addedNodes: [],
+      updatedNodes: [
+        {
+          nodeId: "n-quality-deterioration",
+          previousStatus: null,
+          newStatus: null,
+          previousValue: null,
+          newValue: null,
+          reason: "No further graph change.",
+        },
+      ],
+      addedEdges: [],
+      removedEdgeIds: [],
+      resolvedUnknownNodeIds: [],
+      affectedNodeIds: [],
+      selectedQuestion: null,
+    };
+
+    const result = await applyValidatedProposal({
+      situationGraph: graph,
+      proposal: noOpProposal,
+      evidenceContext: {
+        isCompletedEpisode: true,
+        episodeEvidence: {
+          turns: [{ question: "What did you find?", answer: "No further change." }],
+          eligibleCanonicalFindings: [{ proposition: "The episode is preserved." }],
+        },
+      },
+    });
+
+    expect(result.success).toBe(true);
+    expect(result.updatedSituationGraph.nodes).toEqual(originalGraph.nodes);
+    expect(result.updatedSituationGraph.edges).toEqual(originalGraph.edges);
+  });
+
+  it("still rejects an invalid completed-episode proposal", async () => {
+    const { graph } = makeApplicationFixture();
+
+    const result = await applyValidatedProposal({
+      situationGraph: graph,
+      proposal: {
+        addedNodes: [],
+        updatedNodes: [{ nodeId: "missing-node", reason: "Invalid target." }],
+        addedEdges: [],
+        removedEdgeIds: [],
+        resolvedUnknownNodeIds: [],
+        affectedNodeIds: [],
+        selectedQuestion: null,
+      },
+      evidenceContext: { isCompletedEpisode: true, episodeEvidence: { turns: [] } },
+    });
+
+    expect(result).toMatchObject({ success: false, stage: "proposal_compatibility" });
+    expect(result.errors).toEqual(expect.arrayContaining([
+      expect.stringContaining("Cannot update non-existent node"),
+    ]));
+  });
+
   it("resolves one unknown and adds consequential unknowns with one selected question", () => {
     const { graph, ids } = makeApplicationFixture();