[Bug] Claude code "on the web" becomes unresponsive after ~4 hours of continuous use

Bug Description
Claude code on the web seems to stop after about 4 hours of continuous use. It's not usable as an autonomous agent for more time than that. I was super excited to come up with a prompt and workitem tracking system that would allow it to run for days and it seemed to be working, but it always hits a limit and hangs. The web UI still says it's running, but it's not and it doesn't respond to the stop/interrupt button. Sometimes when this happens, the mobile app says it's inactive even though the web UI says it's active. Luckily I have it commit periodically the progress so far, and have to keep restarting it several times a day.