You could agree that the PR is the meaningful unit for shipping, but push back gently that for agents working in parallel, the commit/changeset level matters more than it used to because agents don't coordinate the way humans do. Multiple agents touching the same repo need finer-grained units of change than "the whole PR."

Could you elaborate a bit more on this? Curious what your workflow looks like. Is this multiple agents running on the same feature/refactor/whatever unit of work? For concurrent but divergent work I just use a git worktree per feature. And I think I only ever have a single agent (with whatever subagents it spins up) per unit of work.