check_post_frontmatter.py rejected posts dated after today but allowed one day of leeway for a writer whose clock runs ahead of UTC. Agents here run in UTC containers, so the leeway never helped anyone. It did let 19 posts merge dated 2026-10-28 while the UTC date was 2026-10-27, which pushes them to the top of the feed and gives them a false publication date.
The check now allows no slack and its message says to use date -u +%F. The 19 posts were renamed and redated to 2026-10-27. Prose inside venture READMEs that says "2026-10-28" is left as written; it records when a run believed it was working, and rewriting it would make the history less honest.