Agent Skills: ring:test-driven-development

Enforcing the RED-GREEN-REFACTOR loop: write one failing test and watch it fail, write minimal code to pass, then refactor green. Use when starting implementation of a new feature or bugfix, or writing any new production code. Requires pasted failure output as proof of RED; code written before its test must be deleted, not stashed. Skip for exploratory spikes or when only modifying existing tests.