FragBench: Cross-Session Attacks Hidden in Benign-Looking Fragments. - Astha Mehta; Niruthiha Selvanayagam; Cedric Lam; Hengxu Li; Phuc-Nguyen Nguyen; Raymond Lee; Olivia McGoffin; My Luong; Arthur Collé; Jamie Johnson; David Williams-King; Linh Le (CoRR, 2026)