With GitHub's stacked PRs feature (gh-stack) now in preview, it would be great if Railway's PR environments could natively handle stacked PR workflows.

Currently Railway creates a preview environment for each PR opened against the default branch. With stacked PRs, you have a chain of PRs where each targets the previous PR's branch rather than main. This means Railway either doesn't spin up environments for the intermediate PRs (since they don't target the default branch), or if it does, the environments don't reflect the full dependency chain correctly.

Ideal behavior would be:

• Railway detects that a PR is part of a stack and deploys the cumulative changes (the full stack up to that PR)
• As individual PRs in the stack are merged and the stack collapses, the remaining PR environments update accordingly
• Preview URLs work correctly for each level of the stack

This is increasingly relevant as more teams adopt stacked PR workflows via gh-stack, Graphite, spr, and similar tools to keep PRs small and reviewable. Would love to see Railway support this natively rather than requiring workarounds.