Data boot

Start Keep once on the server and once on the client. cluaupp init already ships this: ServerScriptService/Boot/DataBoot.server.clpp and StarterPlayerScripts/Controllers/DataController.client.clpp.

Gameplay scripts (PlayerHandler, combat, shop) only WaitFor — they do not call Init.

The save shape is yours. It lives in Shared/Constants/Datas/TemplateData.

Shared template

src/ReplicatedStorage/Shared/Constants/Datas/TemplateData.clh

#pragma once

struct Currencies {
  int Coins = 0;
  int Gems = 0;
};

struct PlayerTemplate {
  Currencies Currencies;
  int Rebirths = 0;
  int Rank = 0;
};

extern PlayerTemplate TemplateData;

Bump .StoreName when you intentionally wipe saves. Changing a field default in TemplateData reconciles missing keys; it does not migrate old values.

Server — DataBoot.server.clpp

#include <clpp/roblox.clh>
#include <clpp/libs/keep.clh>
#include "../../ReplicatedStorage/Shared/Constants/Datas/TemplateData.clh"

void init() {
  PlayerTemplate playerData;
  Keep.Server.Init(DataServiceOptions {
    .Template = playerData,
    .StoreName = "PlayerData",
    .UseMock = true,
  });
}

Field	In production
.Template	Same struct the rest of the game reads through Paths
.StoreName	Stable DataStore name (version it when you wipe)
.UseMock	true in Studio so you do not hit the live store

After Init, Keep.Server.Paths.Currencies.Coins exists because the Template had that table.

Client — DataController.client.clpp

#include <clpp/roblox.clh>
#include <clpp/libs/keep.clh>

void init() {
  Keep.Client.Init();
}

Client Init has no Template. The server already owns the document.

What other scripts do

Data data = Keep.Server.WaitFor(player);
int coins = data.Get(Keep.Server.Paths.Currencies.Coins);

• Server gameplay: WaitFor(player) then Get / Set.
• Client HUD: WaitForData() then Get.
• Trades: Keep.Trade.Begin / Reserve / Commit on server profiles only.
• Never Init twice.

See Keep and file tags.