A simple solution is to use a git hook that asks for confirmation if it is too big, with a suggestion to ask the user to have the agent split it up.

For OSS, my suggestion is to accept issues and specs do the implementation yourself. Warp.dev has a decent model of this in Github: https://github.com/warpdotdev/warp/blob/master/CONTRIBUTING....

Yes could be a pipe failure. Commonly used for coverage or security concerns, it could be also used for PR size.