Hi,

We recently started using Vercel CI in a monorepo where we are making heavy use of GitHub's stacked pull requests feature and turborepo. As is common practice, we'd make better use of the knowledge that these PRs are in a stack to optimize our CI runs, including things like:

• Only running CI against the previous PR in the stack instead of against main (configurable by GitHub actions, but not in Vercel CI, which runs against main due to that being the default for stacked PRs).
• Serialize Vercel CI across a stack (or have the option to) in order to not rerun things which could be in the cache if already ran against a PR earlier in the stack
• Cancel Vercel CI runs later down the stack if we already encounter failures earlier in the stack

Right now, the only trigger is a git push which limits us from being able to work around this ourselves.