fix(sync): block patches before initial hydration (#21)

src/index.d.ts

@@ -290,6 +290,11 @@ declare namespace Charm {
 		 * The atoms to synchronize with the server.
 		 */
 		atoms: Atoms;
+		/**
+		 * Whether to ignore patches sent before the client has been hydrated.
+		 * Defaults to `true`.
+		 */
+		ignoreUnhydrated?: boolean;
 	}
 
 	interface ServerOptions<Molecules extends MoleculeMap> {

src/sync/client.luau

@@ -9,6 +9,11 @@ type ClientOptions = {
 		The atoms to synchronize with the server.
 	]=]
 	atoms: { [string]: Atom<any> },
+	--[=[
+		Whether to ignore patches sent before the client has been hydrated.
+		Default is `true`.
+	]=]
+	ignoreUnhydrated: boolean?,
 }
 
 type ClientSyncer = {
@@ -30,12 +35,22 @@ type ClientSyncer = {
 ]=]
 local function client(options: ClientOptions): ClientSyncer
 	local atoms = options.atoms
+	local ignoreUnhydrated = options.ignoreUnhydrated ~= false
 	local self = {} :: ClientSyncer
+	local hydrated = false
 
 	-- Apply the state changes sent by the server.
 	function self:sync(...)
 		for index = 1, select("#", ...) do
-			local payload = select(index, ...)
+			local payload: SyncPayload = select(index, ...)
+
+			if ignoreUnhydrated and payload.type == "patch" and not hydrated then
+				-- If the client is not initialized, ignore patches. This is
+				-- to prevent patching incomplete state.
+				continue
+			end
+
+			hydrated = true
 
 			store.batch(function()
 				for key, state in next, payload.data do