What problem does it solve? A green build only proves code compiles; it does not prove the feature actually behaves the way the spec promised. This Skill closes that gap by running the real application and checking each observable "done when" criterion from the current feature spec, producing evidence-backed pass/fail results before work is marked complete. ## Core Features & Use Cases - Spec-Driven Checklist: Reads blueprint/context/current-feature.md and converts every "done when" criterion into a concrete, observable claim to verify. - Real App Verification: Drives the actual running app — browser routes for web apps, commands for CLIs, endpoints for servers — capturing screenshots, output, console errors, and failed network requests as evidence. - Honest Reporting: Reports one line per criterion as pass, fail, or skip, never edits source or commits, and hands failures back to /implement with named fixes. - Use Case: After implementing a PDF download feature, run the check to confirm clicking the button actually downloads certificate-<slug>.pdf, loading states render, and no console errors appear — before declaring the feature complete. ## Quick Start Ask the agent to run /check on the current feature to verify every done-when criterion in the spec against the running app.