MCP App UI causes chat to be jittery on mobile but not on desktop

ChatGPT Apps SDK
1

I have two MCP App UI’s that I’ve built for my ChatGPT App. One of them works fine on both mobile and desktop but the other one causes the chat screen on mobile to generate a bunch of white space and scrolling below the app UI. When you scroll down to see the ChatGPT generated text for the chat, it’s also jittery. This doesn’t happen on desktop for ChatGPT. This works without issue on both mobile and desktop for Claude, so I’m guessing that perhaps it’s an issue on the mobile side for ChatGPT. Maybe it keeps adjusting the iframe size? Anyone else experiencing something similar and find a workaround for this?

Mobile:

mobile

2

Figured this out. I was inadvertently setting a min height on the UI to 100%. I’m guessing that was being used to determine the size of the iframe and was probably leading to a weird feedback loop causing continuous resizing. Removed that and it works now. Sharing in case anyone else makes this mistake.

4

Hey @stevenpal, nice catch. That definitely sounds like the mobile iframe was getting stuck in a resize loop from the min-height: 100% setting.

Appreciate you circling back with the root cause too, this is the kind of thing that’ll probably save someone else a lot of debugging time on mobile MCP UIs.

-Mark G.