Coding agents generate Flutter UI fast. The hard problem isn't speed anymore, it's quality. Agents ship pull requests where the code compiles, the tests pass, and the widget looks right at first glance. But the design system has been quietly violated. The layout breaks on a small phone nobody tested. The accessibility label exists but doesn't actually help a screen reader user. Reviewers don't have time to catch all of it. UI debt accumulates at twice the speed. This talk shows a workflow that flips the problem. The agent verifies its own work before a human ever sees the PR. We use Flutter's structured trees (the Widget Tree and the Semantics Tree) as ground truth. Widgetbook turns those trees into compact, actionable diffs that an agent can read, reason about, and fix in a tight loop. Then, and only then, does the human get a clean, summarized PR to review. Code changes can be reviewed in Git while UI changes can be reviewed in Widgetbook Cloud. Widgetbook's customer Couchsurfing will join the stage to showcase how they have been using Widgetbook. Walk away with a complete UI agent-assisted development for Flutter: how to give your design system to an agent as context, how to build self-healing test loops with flutter test, and how to review your agents work.