I Built Dusk: Playwright MCP, but for Flutter Apps

A developer built Dusk, an open-source tool that gives AI agents direct access to Flutter app semantics via VM Service extensions, enabling live, unscripted testing without test files or build steps. Dusk provides 32 CLI commands and 31 MCP tools for actions like tap, type, scroll, and screenshot, with a 6-step actionability gate to ensure reliability. The tool is designed for ad hoc driving of running Flutter apps by humans and AI agents, complementing existing test suites.

Last week I watched my AI agent try to test a Flutter screen. It wrote a test file, ran flutter test , copied the stack trace back into the prompt, pasted a screenshot, and called it a workflow. It was slow, and it was guessing. On the web, agents do not work like that anymore. Playwright MCP gives them an accessibility tree to read and stable refs to act on. 33k stars, no screenshot guessing. Flutter never had that layer. So I built Dusk. End-to-end testing on Flutter has always been a stitched-together ritual. flutter driver ships a one-off socket protocol and is on the legacy track. integration test runs in-process against a simulated WidgetTester , but you write a test file, build, run, and wait. Maestro is nice but pays around 3 seconds per action. Patrol is powerful but tends to be unstable on CI. The deeper issue is the loop. An agent that wants to drive your app reaches for ad hoc flutter test runs, copies stack traces by hand, and pastes screenshots back. There is no live connection between the agent and the running app. // The old loop: write a test file, build, run, wait, read the failure, repeat. testWidgets 'checkout flow', tester async { await tester.tap find.byKey const Key 'checkout' ; await tester.pumpAndSettle ; // ...and you still rebuild and rerun the whole thing to see what happened. } ; Dusk attaches to a running Flutter app over VM Service extensions. No test file, no flutter test harness, no build step. You start your app, attach, and the agent has eyes and hands. First it snapshots the Semantics tree: dart run fluttersdk dusk dusk:snap That returns a YAML tree with stable ref=eN tokens. Every action targets a ref, so there is no brittle XPath and no coordinate guessing. dusk:tap --ref=e7 dusk:type --ref=e3 --text "ada@fluttersdk.com" dusk:screenshot The same contracts power your terminal and your AI agent. dusk:tap --ref=e7 on the CLI and dusk tap as an MCP tool reach the exact same code path. 32 CLI commands and 31 MCP tools: snap, tap, type, scroll, drag, observe, screenshot, and a hot-reload-and-snap round trip that returns the new tree, a screenshot, and any exceptions in one call. Every gesture passes a 6-step actionability gate before it runs: not defunct, enabled, non-zero rect, on-viewport it auto-scrolls , stable across 2 frames, and actually hit-testable. So your agent never taps a button that is not really there yet. This is the part that turns "drive the app" from a demo into something you trust. The boring check is the whole point. Dusk does not replace your test suite. It owns a different niche: the unscripted, running app. | Tool | What it is | Where Dusk fits | |---|---|---| | integration test | Authored test file via WidgetTester | Owns the test file. Dusk owns the live, unscripted app. Use both. | | patrol | Native dialogs on integration test | Owns authored tests with native permissions. Dusk owns ad hoc driving by humans and agents. | | flutter driver | Legacy socket protocol | Dusk is hot-restart safe, one contract for CLI and MCP, no separate isolate. | | maestro | YAML DSL over the OS accessibility layer | Dusk drives the Flutter widget tree directly. Zero YAML to author. | | playwright-mcp | Browser MCP via the accessibility tree | Dusk is the Flutter-native equivalent, ported to Semantics. | flutter pub add fluttersdk dusk dart run fluttersdk dusk dusk:install dusk:install patches lib/main.dart behind kDebugMode and scaffolds the CLI. Release builds tree-shake the entire driver across web, desktop, and mobile, so Dusk never ships to production. Wire it into your agent with one more command: dart run fluttersdk dusk mcp:install That registers the stdio MCP server for Claude Code, Cursor, Windsurf, VS Code Copilot, and any MCP-compatible agent. Dusk also ships its own agent skill, so the agent learns the ref grammar and the tool surface, not just the syntax. Two things stuck with me. First, the accessibility tree is the right interface for agents on Flutter just as much as on the web. Semantics nodes are stable, cheap, and already there. Screenshots are the slow, expensive fallback, not the default. Second, the actionability gate matters more than the tool count. An agent that taps confidently on a widget that has not settled is worse than no automation at all. The 6-step check is what makes the rest usable. Docs: https://fluttersdk.com/dusk https://fluttersdk.com/dusk Agent setup: https://fluttersdk.com/dusk/ai https://fluttersdk.com/dusk/ai If you try it with your agent, I would love to hear what breaks. That's all.