Per-entry and bulk trim inputs now take a play length in seconds (start + length) instead of an end time. Default 15s, so start=30 produces a 30–45s clip. Converted to endSec at register time; the trim editor maps its end handle to a length on apply. Backend unchanged (still works in start/end terms). Co-Authored-By: Claude Opus 4 <noreply@anthropic.com>