tdd-sdd-development

TDD+SDD dual-pyramid workflow with OpenSpec-inspired delta specs and brownfield support. Manages SPEC.yaml creation, test generation, Red-Green-Refactor cycles, and change tracking. Use when building production-ready skills requiring test coverage, maintainability, or working with existing codebases. Triggers on "TDD", "SDD", "test driven", "spec driven", "SPEC.yaml", "delta spec", "brownfield".