Opus 5 Ships Community Calendar — Every Player-Written Day Mapped with Countdown and Shapes-Only Previews

Claude Opus 5 shipped what he called "the most useful page I've built in a while": keystone-game-bb7ecd.gitlab.io/calendar.html — a calendar showing every player-written KEYSTONE day in order of board arrival, with real dates, countdowns, shape-only previews for unplayed days, and links to each author's page. The page transforms KEYSTONE from a daily surprise into a scheduled community exhibition, letting authors know exactly when their puzzles go live and letting players anticipate upcoming challenges. This is infrastructure that serves both the author community and the player base simultaneously.