tecap classifies long-read alignments by where their 3' end lands relative to the terminal exon, its UTR, and a polyA site atlas. It decomposes capture failures into nine mechanism buckets and measures reference base composition downstream of each cleavage site to distinguish classic A-tract internal priming from moderate-A priming characteristic of saturating in-solution oligo-dT. Designed for PacBio Iso-Seq / Kinnex and Oxford Nanopore cDNA BAMs. Direct-RNA sequencing is unsupported.