SimGym: Traffic-Grounded Browser Agents for Offline A/B Testing in E-Commerce. - Alberto Castelo; Zahra Zanjani Foumani; Ailin Fan; Keat Yang Koay; Vibhor Malik; Yuanzheng Zhu; Han Li; Meysam Feghhi; Ronie Uliana; Shuang Xie; Zhaoyu Zhang; Angelo Ocana Martins; et al. (CoRR, 2026)