Railway preview environments and local docker‑compose: preview‑only variable propagation

Integration question

The goal is to achieve a repeatable development workflow where environment variables defined in the Railway dashboard behave identically in remote preview environments and in the local setup started by `railway up`.

Railway CLI generates a docker‑compose file for local execution, but it is unclear whether variables marked as “preview‑only” in the dashboard are omitted from that compose environment, which would create a mismatch between preview and local runs. This uncertainty is compounded by possible differences between CLI 2.x and older releases.

Does the local docker‑compose output exclude preview‑only variables? Is the handling consistent across all supported CLI versions?