Tools

Test-driven development in vertical slices: agree on test seams with the user first, verify behavior only through public interfaces, and avoid listed anti-patterns such as implementation coupling and tautological tests. From Matt Pocock's skills collection.

Forces red-green-refactor: write a test and watch it fail, then write the minimum code to pass. Any code written without a verified failing test gets deleted and redone. From the Superpowers workflow.

Test-driven development plugin: /tdd-workflows:tdd-cycle and related commands move through red-green-refactor phases with a checkpoint for approval at each, plus TDD orchestrator and code reviewer subagents. Part of the wshobson/agents marketplace.