diff --git a/sandbox_probe/probe3.gd b/sandbox_probe/probe3.gd
new file mode 100644
index 0000000..1cb914a
--- /dev/null
+++ b/sandbox_probe/probe3.gd
@@ -0,0 +1,111 @@
+extends Node
+
+func _ready():
+	print("=== SANDBOX PROBE 3: Deep Sandboxing Mechanisms ===")
+	probe_script_restriction_apis()
+	probe_global_scope()
+	probe_classdb_restrictions()
+	probe_engine_singletons()
+	probe_network_restrictions()
+	probe_threading()
+	probe_expression_eval()
+	probe_resource_loading()
+	print("=== SANDBOX PROBE 3 END ===")
+	get_tree().quit()
+
+func probe_script_restriction_apis():
+	print("--- Script restriction APIs ---")
+	# Does GDScript expose any way to restrict globals?
+	var gd = GDScript.new()
+	print("  GDScript methods: ", gd.get_method_list().map(func(m): return m.name))
+	# Check for any 'restrict' or 'allow' methods on the language
+	var lang = GDScriptLanguage.new()
+	print("  GDScriptLanguage methods: ", lang.get_method_list().map(func(m): return m.name))
+	# Check ScriptServer via Engine
+	print("  Engine.get_singleton_list contains ScriptServer: ", "ScriptServer" in Engine.get_singleton_list())
+
+func probe_global_scope():
+	print("--- Global scope ---")
+	# What globals are available to a script?
+	# Test if we can enumerate global classes
+	var globals = []
+	for g in GlobalScope.get_singleton_list():
+		globals.append(g)
+	print("  GlobalScope singletons: ", globals)
+	# Can we access ClassDB to enumerate classes?
+	print("  ClassDB.class_exists('OS'): ", ClassDB.class_exists("OS"))
+	print("  ClassDB.class_exists('FileAccess'): ", ClassDB.class_exists("FileAccess"))
+	print("  ClassDB.class_exists('TCPServer'): ", ClassDB.class_exists("TCPServer"))
+
+func probe_classdb_restrictions():
+	print("--- ClassDB restrictions ---")
+	# Can we instantiate arbitrary classes?
+	var os = ClassDB.instantiate("OS")
+	print("  ClassDB.instantiate('OS') = ", os)
+	# Can we call static methods via ClassDB?
+	print("  ClassDB has method 'class_get_method_list': ", ClassDB.has_method("class_get_method_list"))
+	# Can we access the full class list?
+	var class_list = ClassDB.get_class_list()
+	print("  ClassDB.get_class_list() count: ", class_list.size())
+	print("  First 10 classes: ", class_list.slice(0, 10))
+
+func probe_engine_singletons():
+	print("--- Engine singletons ---")
+	# What singletons are available?
+	var singletons = Engine.get_singleton_list()
+	print("  Engine singletons: ", singletons)
+	# Can we get a singleton by name?
+	for s in ["OS", "Engine", "ProjectSettings", "ResourceLoader", "ClassDB", "Input", "DisplayServer"]:
+		print("  Engine.has_singleton('", s, "'): ", Engine.has_singleton(s))
+
+func probe_network_restrictions():
+	print("--- Network restrictions ---")
+	# Can we make outbound HTTP requests?
+	var http = HTTPRequest.new()
+	print("  HTTPRequest.new() = ", http)
+	# Can we create a WebSocket client?
+	var ws = WebSocketPeer.new()
+	print("  WebSocketPeer.new() = ", ws)
+	# Can we access the network via PacketPeer?
+	var pp = PacketPeerUDP.new()
+	print("  PacketPeerUDP.new() = ", pp)
+
+func probe_threading():
+	print("--- Threading ---")
+	# Can we spawn threads?
+	var thread = Thread.new()
+	print("  Thread.new() = ", thread)
+	# Can we use mutexes / semaphores?
+	var mutex = Mutex.new()
+	print("  Mutex.new() = ", mutex)
+	var sem = Semaphore.new()
+	print("  Semaphore.new() = ", sem)
+
+func probe_expression_eval():
+	print("--- Expression evaluation ---")
+	# Godot's Expression class - can it evaluate arbitrary code?
+	var expr = Expression.new()
+	var err = expr.parse("1 + 2")
+	print("  Expression.parse('1+2') err=", err)
+	if err == OK:
+		var result = expr.execute()
+		print("  Expression.execute() = ", result)
+	# Can Expression access OS?
+	var expr2 = Expression.new()
+	err = expr2.parse("OS.get_environment('HOME')")
+	print("  Expression.parse('OS.get_environment') err=", err)
+	if err == OK:
+		var result2 = expr2.execute()
+		print("  Expression.execute() = ", result2)
+
+func probe_resource_loading():
+	print("--- Resource loading ---")
+	# Can we load arbitrary resources?
+	var res = load("res://test_script.gd")
+	print("  load('res://test_script.gd') = ", res)
+	# Can we load from absolute paths?
+	var res2 = load("/etc/hostname")
+	print("  load('/etc/hostname') = ", res2)
+	# Can we use ResourceLoader directly?
+	var rl = ResourceLoader
+	print("  ResourceLoader.load('res://test_script.gd') = ", rl.load("res://test_script.gd"))