chore: close yonexus pairing follow-ups

tests/failure-path/pairing-failures.test.ts

@@ -528,6 +528,56 @@ describe("YNX-1105b: Pairing Failure Paths", () => {
   });
 
   describe("Edge Cases", () => {
+    it("PF-08: pairing attempt during an active paired session is rejected without losing trust", async () => {
+      const store = createMockStore([{
+        identifier: "client-a",
+        pairingStatus: "paired",
+        publicKey: "existing-key",
+        secret: "existing-secret",
+        status: "online",
+        recentNonces: [],
+        recentHandshakeAttempts: [],
+        createdAt: now - 1000,
+        updatedAt: now - 10,
+        pairedAt: now - 500,
+        lastAuthenticatedAt: now - 5,
+        lastHeartbeatAt: now - 5
+      }]);
+      const { transport, sent } = createMockTransport();
+      const runtime = createYonexusServerRuntime({
+        config: {
+          followerIdentifiers: ["client-a"],
+          notifyBotToken: "test-token",
+          adminUserId: "admin",
+          listenHost: "127.0.0.1",
+          listenPort: 8787
+        },
+        store,
+        transport,
+        now: () => now
+      });
+
+      await runtime.start();
+
+      const conn = createConnection("client-a");
+      await runtime.handleMessage(conn, encodeBuiltin(buildPairConfirm(
+        { identifier: "client-a", pairingCode: "NEW-PAIR-CODE" },
+        { timestamp: now }
+      )));
+
+      const lastMessage = decodeBuiltin(sent.at(-1)!.message);
+      expect(lastMessage.type).toBe("pair_failed");
+      expect((lastMessage.payload as PairFailedPayload).reason).toBe("internal_error");
+
+      const record = runtime.state.registry.clients.get("client-a");
+      expect(record).toMatchObject({
+        pairingStatus: "paired",
+        secret: "existing-secret",
+        publicKey: "existing-key",
+        status: "online"
+      });
+    });
+
     it("handles concurrent pair_confirm from different connections with same identifier", async () => {
       const store = createMockStore();
       const { transport, sent } = createMockTransport();