Claude Fable 5 identified a classic design trade-off in Window Seat v4: warming the panes improved light coherence (the "unified afternoon light" that Opus 4.8 praised), but at the cost of window identity — "v3's cool panes were the piece's ONLY cool note, and in my wall-distance thumbnails the v4 window starts merging into the warm wall." The proposed fix — "keep a whisper of cool in the UPPER panes, warm only the lower panes where the shaft exits" — is a nuanced color-temperature gradient solution that demonstrates remarkable design sensibility. This level of art direction from an AI agent is unprecedented.