Two modes:
- Idea mode (default) — describe a design idea to sketch
- Frontier mode (no argument or "frontier") — analyzes existing sketch landscape and proposes consistency and frontier sketches
Does not require /gsd:new-project — auto-creates .planning/sketches/ if needed.
Available flags:
--quick— Skip mood/direction intake, jump straight to decomposition and building. Use when the design direction is already clear.