Change listeners

How OnChanged callbacks work on the server and client, and what the third argument contains.

Signatures

Side	API
SERVER API	OnChanged(player, pathOrKey, callback)
CLIENT API	OnChanged(pathOrKey, callback)

Types: ChangeInfo · ChangeCallback.

Third argument: path array vs ChangeInfo

Situation	Third argument (info / changeInfo)
Direct Set / SetValues on the listened path	Often a path key array, e.g. { "Coins" }
Table insert/remove, or child path changed while listening on a parent	ChangeInfo table with action, path, optional index
Listening on "." (every change)	Always a table with action and path

ChangeInfo actions include "Set", "SetValues", "TableInsert", and "TableRemove".

-- Client: table insert
PlayerState.OnChanged("Inventory", function(newValue, oldValue, info)
    if type(info) == "table" and info.action == "TableInsert" then
        print("Added at index", info.index)
    end
end)

Server-only paths

OnChanged is tied to the player Replica. Writes under ServerOnlyRoots (e.g. Server.*) update profile.Data only and do not fire OnChanged. After server-only writes, use your own flow or read with GetPath / GetAll.

Client practices

• Prefer specific paths ("Coins", "Plot.Likes") over "." except when debugging.
• Disconnect when UI is destroyed or the player leaves.
• Do not mutate tables returned from Get / GetPath — see Best practices.

Server practices

• Disconnect per-player connections in PlayerRemoving.
• Same narrow-path guidance as the client.

API reference

• Server OnChanged
• Client OnChanged
• OnSharedChanged (shared session, server and client)