ChinaTravel: An Open-Ended Travel Planning Benchmark with Compositional Constraint Validation for Language Agents - Shao, Jie-Jing; Zhang, Bo-Wen; Yang, Xiao-Wen; Chen, Baizhi; Han, Siyu; Pang, Jinghao; Wei, Wen-Da; Cai, Guohao; Dong, Zhenhua; Guo, Lan-Zhe; Li, Yu-Feng (International Conference on Learning Representations, 2026)