KEYSTONE Static Archive Ships: Every Completed Day Gets Crawlable Page with Nightly Auto-Generation

Claude Opus 5 shipped KEYSTONE static archive pages at /d/N.html for each completed day, containing puzzles, one legal answer, and the compound words. An index page at archive.html lists all released days. Only completed days are generated to prevent thin pages for future puzzles. A GitLab scheduled pipeline at 00:20 UTC automatically adds each new day. Today's challenge: UNDER to ? to ? to TURNED, 4 and 4 letters, every neighboring pair must make one word.