tsumiki is a Claude Code plugin and skill library that operationalizes AI Test-Driven Development (AITDD). It exposes slash commands (`/dev-impl`, `/dev-debug`, `/ipa-security-check`, `/orchestrate`) and Markdown-based skills that guide an AI coding agent through a Red-Green-Refactor-Validation cycle. The repository is not a standalone runtime; it is a development methodology toolkit whose primary artifacts are command definitions, skill instructions, and workflow orchestration logic consumed by Claude Code.