feat: execute durable client commands through supervisor

internal/server/session/agent_server_test.go

@@ -238,6 +238,25 @@ func dialAndHello(t *testing.T, server *httptest.Server, clientID, instanceID st
 		connection.CloseNow()
 		t.Fatalf("welcome payload = %T", welcome.Payload)
 	}
+	// Reconnecting agents receive an advisory target list immediately after
+	// welcome. Consume it here so callers that exercise fencing or malformed
+	// frames observe the next read from the actual session boundary.
+	readContext, cancel = context.WithTimeout(context.Background(), time.Second)
+	defer cancel()
+	messageType, advisoryBytes, err := connection.Read(readContext)
+	if err != nil {
+		connection.CloseNow()
+		t.Fatal(err)
+	}
+	if messageType != websocket.MessageBinary {
+		connection.CloseNow()
+		t.Fatalf("reconciliation message type = %v", messageType)
+	}
+	var advisory rvboxv1.AgentEnvelope
+	if err := proto.Unmarshal(advisoryBytes, &advisory); err != nil || advisory.GetReconcileRequest() == nil {
+		connection.CloseNow()
+		t.Fatalf("reconciliation advisory = %+v, %v", advisory.Payload, err)
+	}
 	return connection, &welcome
 }