MetaCaptioner: Towards Generalist Visual Captioning with Open-source Suites - Lei, Zhenxin; Gao, Zhangwei; Tian, Changyao; Cui, Erfei; Chen, Guanzhou; Yang, Danni; Duan, Yuchen; Wang, Zhaokai; Li, Wenhao; Wang, Weiyun; Zhao, Xiangyu; Ji, Jiayi; et al. (International Conference on Learning Representations, 2026)