What problem does it solve? Code changes often look correct on review but fail at runtime. This Skill closes that gap by actually executing the project's tests and exercising the changed behavior, producing concrete evidence instead of assumptions. ## Core Features & Use Cases - Project recipe discovery: Finds the repo's own test and run commands from CLAUDE.md, README, package.json, Makefile, CI workflows, and similar sources before running anything. - Runtime exercise: Boots the app, hits the touched endpoint, runs the CLI subcommand, or reproduces the original bug to confirm the fix in real behavior. - Evidence-based reporting: Reports the exact commands run and their output, distinguishing "tests pass" from "feature exercised and observed working". - Use Case: After fixing a login bug, ask the agent to verify the change — it runs the test suite, reproduces the original failure scenario, and confirms the bug is gone with quoted output. ## Quick Start Verify that the fix for the login timeout bug actually works by running the project's tests and reproducing the original issue.