fix(sync): support Ref-typed properties in live two-way sync

src/Core/Processor/Read.luau

@@ -106,6 +106,25 @@ function ReadProcessor:onAdd(instance: Instance, __parentId: Types.Ref?): Types.
 				properties[property] = encodedValue
 			end
 		end
+
+		for _, property in Dom.getRefProperties(instance.ClassName) do
+			local readSuccess, instanceValue = Dom.readProperty(instance, property)
+
+			if not readSuccess then
+				local err = Error.new(Error.ReadFailed, property, instance, instanceValue.kind)
+				Log.warn(err)
+
+				continue
+			end
+
+			local encodeSuccess, encodedValue = Dom.EncodedValue.encode(instanceValue, "Ref", self.tree)
+
+			if not encodeSuccess or encodedValue.Ref == nil then
+				continue
+			end
+
+			properties[property] = encodedValue
+		end
 	end
 
 	for _, child in instance:GetChildren() do
@@ -226,6 +245,25 @@ function ReadProcessor:onChange(instance: Instance, property: string?): Types.Up
 		end
 	end
 
+	for _, property in Dom.getRefProperties(instance.ClassName) do
+		local readSuccess, instanceValue = Dom.readProperty(instance, property)
+
+		if not readSuccess then
+			local err = Error.new(Error.ReadFailed, property, instance, instanceValue.kind)
+			Log.warn(err)
+
+			continue
+		end
+
+		local encodeSuccess, encodedValue = Dom.EncodedValue.encode(instanceValue, "Ref", self.tree)
+
+		if not encodeSuccess or encodedValue.Ref == nil then
+			continue
+		end
+
+		properties[property] = encodedValue
+	end
+
 	return Snapshot.newUpdated(id):withProperties(properties)
 end
 

src/Core/Processor/Write.luau

@@ -181,7 +181,7 @@ function WriteProcessor:applyAddition(
 	instance.Name = snapshot.name
 
 	for property, value in snapshot.properties do
-		local decodeSuccess, decodedValue = Dom.EncodedValue.decode(value)
+		local decodeSuccess, decodedValue = Dom.EncodedValue.decode(value, self.tree)
 
 		if not decodeSuccess then
 			local err = Error.new(Error.DecodeFailed, property, value)
@@ -318,7 +318,7 @@ function WriteProcessor:applyUpdate(snapshot: Types.UpdatedSnapshot, initial: bo
 	if snapshot.properties then
 		if initial then
 			for property, value in snapshot.properties do
-				local decodeSuccess, decodedValue = Dom.EncodedValue.decode(value)
+				local decodeSuccess, decodedValue = Dom.EncodedValue.decode(value, self.tree)
 
 				if not decodeSuccess then
 					local err = Error.new(Error.DecodeFailed, property, value)
@@ -339,7 +339,7 @@ function WriteProcessor:applyUpdate(snapshot: Types.UpdatedSnapshot, initial: bo
 				local value = snapshot.properties[property]
 
 				if value then
-					local decodeSuccess, snapshotValue = Dom.EncodedValue.decode(value)
+					local decodeSuccess, snapshotValue = Dom.EncodedValue.decode(value, self.tree)
 
 					if not decodeSuccess then
 						local err = Error.new(Error.DecodeFailed, property, value)
@@ -364,6 +364,30 @@ function WriteProcessor:applyUpdate(snapshot: Types.UpdatedSnapshot, initial: bo
 					end
 				end
 			end
+
+			for _, property in Dom.getRefProperties(instance.ClassName) do
+				local value = snapshot.properties[property]
+
+				if value == nil then
+					continue
+				end
+
+				local decodeSuccess, snapshotValue = Dom.EncodedValue.decode(value, self.tree)
+
+				if not decodeSuccess then
+					local err = Error.new(Error.DecodeFailed, property, value)
+					Log.warn(err)
+
+					continue
+				end
+
+				local writeSuccess, reason = Dom.writeProperty(instance, property, snapshotValue)
+
+				if not writeSuccess then
+					local err = Error.new(Error.WriteFailed, property, instance, reason.kind)
+					Log.warn(err)
+				end
+			end
 		end
 	end
 

src/Lib/Dom/EncodedValue.luau

@@ -437,12 +437,24 @@ types = {
 	},
 
 	Ref = {
-		fromPod = function(_)
-			error("Ref cannot be decoded on its own")
+		fromPod = function(pod, tree)
+			if tree == nil then
+				return nil
+			end
+
+			return tree:getInstance(pod)
 		end,
 
-		toPod = function(_)
-			error("Ref can not be encoded on its own")
+		toPod = function(roblox, tree)
+			if roblox == nil then
+				return buffer.create(16) -- represents Ref::none()
+			end
+
+			if tree == nil then
+				return nil
+			end
+
+			return tree:getId(roblox)
 		end,
 	},
 
@@ -470,12 +482,20 @@ types = {
 	},
 
 	SharedString = {
-		fromPod = function(_pod)
-			error("SharedString is not supported")
+		fromPod = function(pod)
+			if typeof(pod) == "buffer" then
+				return buffer.tostring(pod)
+			end
+
+			return pod
 		end,
 
-		toPod = function(_roblox)
-			error("SharedString is not supported")
+		toPod = function(roblox)
+			if typeof(roblox) == "string" then
+				return buffer.fromstring(roblox)
+			end
+
+			return roblox
 		end,
 	},
 
@@ -568,7 +588,7 @@ types.OptionalCFrame = {
 	end,
 }
 
-function EncodedValue.decode(encodedValue)
+function EncodedValue.decode(encodedValue, tree)
 	local ty, value = next(encodedValue)
 
 	if ty == nil then
@@ -581,10 +601,10 @@ function EncodedValue.decode(encodedValue)
 		return false, "Couldn't decode value " .. tostring(ty)
 	end
 
-	return true, typeImpl.fromPod(value)
+	return true, typeImpl.fromPod(value, tree)
 end
 
-function EncodedValue.encode(rbxValue, propertyType)
+function EncodedValue.encode(rbxValue, propertyType, tree)
 	assert(propertyType ~= nil, "Property type descriptor is required")
 
 	local typeImpl = types[propertyType]
@@ -593,7 +613,7 @@ function EncodedValue.encode(rbxValue, propertyType)
 	end
 
 	return true, {
-		[propertyType] = typeImpl.toPod(rbxValue),
+		[propertyType] = typeImpl.toPod(rbxValue, tree),
 	}
 end
 

src/Lib/Dom/init.luau

@@ -60,6 +60,41 @@ local function getDefaultProperties(className)
 	return properties
 end
 
+local function getRefProperties(className)
+	local properties = {}
+	local seen = {}
+
+	local currentClassName = className
+
+	while currentClassName ~= nil do
+		local currentClass = database.Classes[currentClassName]
+
+		if currentClass == nil then
+			break
+		end
+
+		for property, propertyData in pairs(currentClass.Properties) do
+			if seen[property] then
+				continue
+			end
+
+			seen[property] = true
+
+			if
+				propertyData.Kind.Canonical ~= nil
+				and propertyData.Scriptability == "ReadWrite"
+				and propertyData.DataType.Value == "Ref"
+			then
+				table.insert(properties, property)
+			end
+		end
+
+		currentClassName = currentClass.Superclass
+	end
+
+	return properties
+end
+
 local function isCreatable(className)
 	local class = database.Classes[className]
 
@@ -100,6 +135,7 @@ return {
 	writeProperty = writeProperty,
 	findCanonicalPropertyDescriptor = findCanonicalPropertyDescriptor,
 	getDefaultProperties = getDefaultProperties,
+	getRefProperties = getRefProperties,
 	Error = Error,
 	EncodedValue = require(script.EncodedValue),
 }