Design

This skill designs a single system within a specific milestone, after /gat-brainstorm (overview) and /gat-milestone (milestone plan) are done. For story, worldbuilding, characters, quests, dialogue, or authored narrative content, delegate to /gat-story. For the initial concept interview, delegate to /gat-brainstorm.

The milestone argument is mandatory. If it is omitted, the skill stops and asks the user to specify a milestone — no inference, default, or fallback.