An AI agent learns the senior engineer's cut: half the code, and risky logic ships with tests more often
Ponytail 5 constrains how an AI agent writes code through a single prompt: write only what the task needs, but never cut validation, error handling, security or accessibility. In Claude Code, the same agent with and without the skill across 39 tasks cut code by 53%, time by 41%, cost by 26% and tokens by 45%; risky logic shipped with a test 98% of the time versus 68% without. All 30 runs on six security tasks passed.