Enhance property encoding and class descriptor retrieval in rbx_dom_lua

- Introduced a new function, `findClassDescriptor`, to retrieve class properties and metadata, including inherited properties, from the database.
- Updated `encodeInstance` to include encoding for Tags alongside Attributes, ensuring comprehensive property serialization.
- Improved property filtering logic to skip non-serializable properties and those matching default values, aligning with syncback behavior.
- Enhanced comments for clarity on property handling and encoding processes.

plugin/rbx_dom_lua/init.lua

@@ -2,6 +2,51 @@ local database = require(script.database)
 local Error = require(script.Error)
 local PropertyDescriptor = require(script.PropertyDescriptor)
 
+-- Returns a class descriptor with all property names and metadata (including inherited ones)
+-- Returns nil if the class doesn't exist in the database
+-- The properties table maps property names to metadata (scriptability, serialization status)
+-- To get a full PropertyDescriptor for encoding, use findCanonicalPropertyDescriptor
+local function findClassDescriptor(className)
+	local classData = database.Classes[className]
+	if classData == nil then
+		return nil
+	end
+
+	-- Build a table of all properties, walking up the inheritance chain
+	local allProperties = {}
+	local currentClassName = className
+
+	repeat
+		local currentClass = database.Classes[currentClassName]
+		if currentClass == nil then
+			break
+		end
+
+		-- Add properties from this class (don't override if already set by subclass)
+		for propertyName, propertyData in pairs(currentClass.Properties) do
+			if allProperties[propertyName] == nil then
+				-- Only include canonical properties (not aliases)
+				if propertyData.Kind and propertyData.Kind.Canonical then
+					allProperties[propertyName] = {
+						name = propertyName,
+						scriptability = propertyData.Scriptability,
+						dataType = propertyData.DataType,
+						serialization = propertyData.Kind.Canonical.Serialization,
+					}
+				end
+			end
+		end
+
+		currentClassName = currentClass.Superclass
+	until currentClassName == nil
+
+	return {
+		name = classData.Name,
+		superclass = classData.Superclass,
+		properties = allProperties,
+	}
+end
+
 local function findCanonicalPropertyDescriptor(className, propertyName)
 	local currentClassName = className
 
@@ -65,6 +110,7 @@ return {
 	readProperty = readProperty,
 	writeProperty = writeProperty,
 	findCanonicalPropertyDescriptor = findCanonicalPropertyDescriptor,
+	findClassDescriptor = findClassDescriptor,
 	Error = Error,
 	EncodedValue = require(script.EncodedValue),
 }