xstate-v5 (Strict) Skill

Build, refactor, and review XState v5 state machines (TypeScript and React) using a strict, strongly-typed ruleset.

Source of truth: references/xstate-v5-rules.md (this repo, resolved from the skill root). If anything in this skill conflicts with the rules file, follow the rules file.

Inlined Non-Negotiable Contract (Agent Must Follow)

These requirements are intentionally duplicated here so an agent can comply without first loading external references: