SciTraj is the first claim-grounded typed citation corpus that links each citation to a specific claim sentence. It includes 32,559 papers from NLP, ML, and Vision (2015–2024) with 573,126 directed edges across six relation types, and 287M typed trajectories of length ≥3, covering 72.8% of papers. The corpus enables analysis of disciplinary siloing and topic emergence, with validated claim seeds and a temporally split link-prediction benchmark.