Milestone

This skill writes:

• production/milestone.md
• production/milestone-xx-name/

Phase 1: Validate Inputs

Fail if any of these are missing:

• design/gdd/game.md
• design/gdd/systems-index.md
• design/art/art-direction.md

Also stop if no system GDDs exist in design/gdd/ besides game.md and systems-index.md.

Read:

• design/gdd/game.md
• design/gdd/systems-index.md
• all existing design/gdd/*.md except game.md and systems-index.md
• design/art/art-direction.md
• all existing design/art/*-art.md
• .claude/docs/templates/plan/milestone.md
• production/milestone.md if exists

Phase 2: Hand Off To The Planner

Spawn gat-planner agent with all read content plus:

• instruction to write or update production/milestone.md
• instruction to define milestone directories using pattern production/milestone-01-name/
• planning focus from argument if provided

The planner should:

• choose a small set of meaningful milestones
• give each a clear goal and named system set
• define code focus and art focus per milestone
• include sequencing notes and milestone-level risks
• keep milestone names short and path-safe

Phase 3: Review

Summarize how many milestones were planned and which comes first.

Use AskUserQuestion:

• Plan first milestone (Recommended) → Run /gat-plan
• Stop here