Lua-in-Vim 9.0: backupcopy divergence for zero-downtime migration

This question examines the interaction between Vim 9.0 Lua integration and the backupcopy option when migrating a small application without service interruption. The objective is to achieve configuration changes while the application remains operational.

A key uncertainty is the presence of the +lua feature in the target Vim build, which is not guaranteed across all distributions, and the documented variance of set backupcopy=yes between Unix and Windows platforms, where file-copy semantics may differ and affect Lua state retention.

To what extent can backupcopy=yes preserve Lua-sourced edits during cross-platform migration, and does the undocumented migrate command present a viable path or a data-loss risk? How does view mode session persistence support continuous operation when Vim is restarted on a different system?