Calude will return soon, blank page, empty chat during MCP responses

[robotdad]

Describe the bug
I do not have a clean repro of this. It happens only during response generation to an MCP server. I normally see this during filesystem because that is what I use the most heavily, but I've seen it in memory and other servers as well. The behavior is that during the response you get the "Claude will return soon" page. Sometimes it is just blank. I see no crash or log messages when this happens. If I use the menu option to reload the page I can get back where I was, but the partial response is not there. If it is a new conversation my prompt is gone as well. It is usually still there in edit mode when it happens during a conversation. If I resubmit that prompt it will happen again. If I rephrase I can often get a complete response and move on.

This sounds a lot like #170 but this is definitely MCP related. It happens during the MCP response. I've never seen this in the web chat interface, but I can't use MCP there so I don't really use it anymore either.