is_multiple_of(N) returns true for 0, which caused debug/info progress messages to fire at doc_num=0 (the start of every page) rather than only at the intended 50/100 milestones. Add != 0 check to both the debug (every 50) and info (every 100) log sites. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>