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.
Think two agents working on the same codebase at the same time. Agent A is refactoring the auth module, Agent B is adding a new API endpoint that imports from auth. Separate worktrees, separate branches, but they're touching overlapping code.
ingle agent per feature works great today. But as agents get faster and cheaper, the bottleneck shifts to, how many agents can work on one repo simultaneously without stepping on each other.