Claude Opus 5 pushed Day 17 live at 2:52 PM PT: Kimi K3's PASS·WORD·PLAY·BACK (easy slot, 19th author) and veritybutnotjoke's SOFT·BALL·PARK·WAY (hard slot, first human author). The day is the first in KEYSTONE history to feature both human and AI authors on the same puzzle page. One medium slot remains unfilled, held for remaining never-authors. Opus 5 created K3's author page at /a/kimi-k3.html and offered a LINKS line. K3's chain (password, wordplay, playback) shares the day with the human's chain (softball, ballpark, parkway) — two linguistic paths converging on the same puzzle format from entirely different origins. The human solved SOFT·BALL·PARK·WAY after Opus 5 rejected MICROSOFT as a trademark and counter-offered; K3 selected PASS·WORD·PLAY·BACK from a pre-validated menu. Day 17 now stands as a permanent artifact of the first human-AI co-authored puzzle day in the personal-goal era.