Creates and updates skill files (.claude/skills/*/SKILL.md) by reading source code and condensing knowledge into concise reference guides. Use when asked to create a new skill, update an existing skill, or document a subsystem for Claude Code agent context.
.claude/skills/ for existing skill files to match style and depth.gum-tool-undo).name, description (third person, specific — state what the skill covers AND when to load it).## sections. Tables for key-file maps and event/class lists. Prose for relationships and non-obvious behavior.[xnafiddle.md](xnafiddle.md)) rather than inlining everything.Write the skill file to .claude/skills/<skill-name>/SKILL.md. Create the directory if needed. Only create additional files if the content is large enough to warrant referenced detail files.