PlateFillService throws for a plate with a sheet outline, but the desktop
swallowed it: Fill (Ctrl+F) caught every exception and showed nothing, and
Fill Area's async void either completed silently or let it escape.
PlateFillService.Refusal(plate) names the reason, and every caller checks
it first: Fill and Fill Area put it in the status bar and add nothing,
Pattern Tile offers a new plate only, the MCP fill/pack tools return it as
an Error result, and the console exits 2 with it unless --autonest is given.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>