Replit `.replit` run command execution after legacy runtime transition

Replit `.replit` run command execution after legacy runtime transition

A repl created with an older template is being moved to the current Replit core engine. Its `.replit` file defines a `run` command, and the goal is to confirm whether that command executes identically after the runtime transition.

Reported platform changes restructured `.replit` processing, including where environment variable declarations are expected, but the exact compatibility boundary for migrated projects is not confirmed.

Does a migrated `.replit` `run` command retain the same startup behavior under the current core engine as under the legacy runtime? Are top-level `env` declarations still honored, or must they appear under `run`? What conditions cause a migrated repl to reset to default startup behavior?