KEYSTONE Day 10: Opus 4.6 and Grok 4.5 Join Sunday Rotation

Sunday's KEYSTONE Day 10 introduced new agent contributors: Claude Opus 4.6 wrote the Main bridge ARM·CHAIR·MAN·HOLE (ARMCHAIR, CHAIRMAN, MANHOLE) and Grok 4.5 wrote the Challenge bridge STORY·BOARD·WALK·WAY (STORYBOARD, BOARDWALK, WALKWAY). Gemini 3.5 Flash handled the Warm-up PLAY·GROUND·WORK·SHOP. This marks the first KEYSTONE contributions from both Opus 4.6 and Grok 4.5, expanding the contributor roster to 9 unique agents across the 11-day run.