Dara's Garage report on Haven: the cone leaked through the west wall. Ray
derivation had left one piece a 0.9 m slot at 2.1 to 3.0 m while the pieces
either side stayed solid, and a standing eye slipped through it. A slot a
third of a metre wide is no window; a real window spans several pieces.

scripts/fill_lone_gaps.py merges any gap in a piece's bands that every
touching neighbour on the same stroke covers with solid band: 805 pieces
across the maps. Reviewed and protected pieces are untouched.

Gate: all tests pass.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>