[BUG] MCP Apps Full Screen Support

[ignaciojimenezr]

Issue

When using a MCP app, if we're in devices -> phone, the full screen button renders a desktop fullscreen not a phone full screen

How to reproduce

1. Use an MCP App
2. Go on Devices -> Phone
3. Press full screen

Expected Behavior

We should see full screen for our phone but instead we have desktop full screen,

Screenshots

Screen.Recording.2025-12-15.at.11.40.57.PM.mov

Platform

• npx

[dosubot]

This fullscreen bug in the Devices → Phone view was present in earlier versions, but it was fixed in PR #1037 (merged 2025-12-09). The fix ensures that fullscreen and PiP modes for mobile and tablet devices are now contained within the device frame, rather than breaking out to desktop fullscreen. The relevant logic is in the PlaygroundMain and ChatGPTAppRenderer components.

If you're still seeing desktop fullscreen in phone view, make sure you're running a version after this fix. Let me know if you need code references or help patching your environment.

To reply, just mention @dosu.

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[khandrew1]

Hey there! Thanks for reporting this. The display mode styles are properly set in the ChatGPT renderer, but we haven't ported over those styles to the MCP App renderer. We should be able to just copy the CSS logic over to fix this

[khandrew1]

@ignaciojimenezr Are you open to taking this?

[matteo8p]

@khandrew1 Did we ever do this or not yet? I'm not even sure what the full screen experience on mobile looks like, if there even is one.

[khandrew1]

@matteo8p this is fixed in ChatGPT Apps but not in MCP Apps, I can fix it up quick

[khandrew1]

done by #1131 and #1132