Wallfacer

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When It's AvailableThe Simulator CanvasIf The Preview Doesn't AppearInteracting with the SimulatorTriggering RebuildsBuild LogsSide-by-Side Layout

iOS Simulator Preview

Wallfacer streams a live iOS Simulator directly into your task view. Watch your app update in real time as Claude makes changes.

When It's Available

Your environment must meet these requirements:

  • Platform set to darwin/arm64 (macOS).
  • An iOS simulator configured in the environment manifest.
  • Xcode and the iOS Simulator are pre-installed on all macOS VMs.

If your environment doesn't use macOS, the simulator preview won't appear.

The Simulator Canvas

The preview is a live 30fps H.264 video stream delivered over WebSocket. It renders directly in the task detail view alongside the chat. The stream starts automatically when the simulator boots inside the VM.

If The Preview Doesn't Appear

The preview is independent of the rest of the task. When the video stream is unreachable as the VM starts, the task still comes up: the simulator boots, Claude's simulator tools work, and only the preview panel stays empty. The stream retries in the background, and the preview appears on its own once it reconnects. Nothing needs restarting.

Screenshots and rebuilds keep working while the preview is empty, so you can still see the app by asking Claude for a screenshot.

Interacting with the Simulator

The simulator supports remote input:

  • Touch -- Tap and multi-touch gestures.
  • Swipe -- Scroll and swipe navigation.
  • Device controls -- Change appearance (light/dark), orientation, location, and biometrics.

Claude can also interact with the simulator directly through its MCP tools -- taking screenshots, tapping elements, swiping, and typing text.

Triggering Rebuilds

After Claude makes code changes, you need to rebuild to see the results:

  • Use the rebuild button in the simulator controls.
  • Or ask Claude directly: "Build and run the app."

Claude runs the Xcode build inside the VM and launches the updated app in the simulator.

Build Logs

When a build is in progress or has failed, view the Xcode build output to diagnose issues. Build logs are accessible from the simulator panel.

Side-by-Side Layout

  • Web and tablet -- The chat panel and simulator preview sit side by side in resizable panels. Drag the divider to adjust proportions.
  • Phone -- Chat and simulator are separate views. Switch between them using navigation.