What is this?

A datastore library for Roblox with no session locks. You never write state. You write down the change you want, a function you own decides whether it is valid, and state is what falls out of replaying those changes.

local Store = Ledger.New({
	Name = "PlayerData",
	Default = { Gold = 100, Items = {} },
	Reducer = function(State, Op)
		if Op.Kind == "SpendGold" then
			if Op.Amount > State.Gold then
				return nil -- refused, on every server, forever
			end
			local Next = table.clone(State)
			Next.Gold -= Op.Amount
			return Next
		end
		return nil
	end,
})

Store:Load(Player)
Store:Expect(Player):Apply("SpendGold", { Amount = 25 })

Two servers spend the same 100 gold, both writes land, the fold accepts one and refuses the other. Every server agrees, every time.

A session lock serializes writers. A validating fold makes the invalid state unreachable, which is a stronger guarantee that also costs nothing when a server crashes: no lease to wait out, no locked player join stall, no side channel to touch someone offline or on another server. Changes are ops with names, and a reducer validates them.

Features

• Lock free | every server, same result, no locks
• Cross server | write to any player, even offline
• Entity stores | clans, listings, world records
• Transfers | escrowed, deduped, self-healing
• Transactions | all keys move or none do
• Migrations | old servers can't corrupt new data
• Recovery | 30 days of history, auto cleanup
• Idempotent | a write retried applies one time
• Once | receipts and webhooks land exactly once
• Loud misuse | bad code throws, immediately

Installing

Wally

[server-dependencies]
Ledger = "xoifaii/ledger@4.1.0"

Model file: insert the Ledger module anywhere server side.

License

This project is licensed under the MIT License.