Server and client attributes

[[server]]
void SaveData(Player player) {
    post("saving " .: player.Name);
}

[[client]]
void UpdateUI() {
    post("ui");
}

File	[[server]]	[[client]]
*.server.clpp	kept	omitted
*.client.clpp	omitted	kept
Module (no tag)	wrapped in RunService:IsServer()	IsClient()

Use attributes instead of copying whole files. Shared modules can expose both functions; the emit guards them.

Next: Declarative UI with Fusion.