fix: insert global assignments after class definitions to prevent NameError

When LLM-generated optimizations include module-level code like
`_REIFIERS = {MessageKind.XXX: ...}`, the global assignment was being
inserted right after imports, BEFORE the class definition it referenced,
causing NameError at module load time.

Changes:
- GlobalAssignmentTransformer now inserts assignments after all
  class/function definitions instead of right after imports
- GlobalStatementCollector now skips AnnAssign (annotated assignments)
  so they are handled by GlobalAssignmentCollector instead

codeflash/code_utils/code_extractor.py

@@ -280,8 +280,12 @@ class GlobalAssignmentTransformer(cst.CSTTransformer):
         ]
 
         if assignments_to_append:
-            # after last top-level imports
+            # Start after imports, then advance past class/function definitions
+            # to ensure assignments can reference any classes defined in the module
             insert_index = find_insertion_index_after_imports(updated_node)
+            for i, stmt in enumerate(new_statements):
+                if isinstance(stmt, (cst.FunctionDef, cst.ClassDef)):
+                    insert_index = i + 1
 
             assignment_lines = [
                 cst.SimpleStatementLine([assignment], leading_lines=[cst.EmptyLine()])
@@ -331,8 +335,8 @@ class GlobalStatementCollector(cst.CSTVisitor):
     def visit_SimpleStatementLine(self, node: cst.SimpleStatementLine) -> None:
         if not self.in_function_or_class:
             for statement in node.body:
-                # Skip imports
-                if not isinstance(statement, (cst.Import, cst.ImportFrom, cst.Assign)):
+                # Skip imports and assignments (both regular and annotated)
+                if not isinstance(statement, (cst.Import, cst.ImportFrom, cst.Assign, cst.AnnAssign)):
                     self.global_statements.append(node)
                     break
 

tests/test_code_context_extractor.py

@@ -2975,11 +2975,11 @@ class MyClass:
         return cached_helper(5)
 """
 
+    # Global assignments are now inserted AFTER class/function definitions
+    # to ensure they can reference classes defined in the module
     expected = """\
 from typing import Any
 
-_LOCAL_CACHE: dict[str, int] = {}
-
 class MyClass:
     def method(self):
         return cached_helper(5)
@@ -2992,6 +2992,71 @@ def cached_helper(x: int) -> int:
 
 def regular_helper():
     return "regular"
+
+_LOCAL_CACHE: dict[str, int] = {}
+"""
+
+    result = add_global_assignments(source_code, destination_code)
+    assert result == expected
+
+
+def test_add_global_assignments_references_class_defined_in_module():
+    """Test that global assignments referencing classes are placed after those class definitions.
+
+    This test verifies the fix for a bug where LLM-generated optimization code like:
+        _REIFIERS = {MessageKind.XXX: lambda d: ...}
+    was placed BEFORE the MessageKind class definition, causing NameError at module load.
+
+    The fix ensures that new global assignments are inserted AFTER all class/function
+    definitions in the module, so they can safely reference any class defined in the module.
+    """
+    source_code = """\
+import enum
+
+class MessageKind(enum.StrEnum):
+    ASK = "ask"
+    REPLY = "reply"
+
+_MESSAGE_HANDLERS = {
+    MessageKind.ASK: lambda: "ask handler",
+    MessageKind.REPLY: lambda: "reply handler",
+}
+
+def handle_message(kind):
+    return _MESSAGE_HANDLERS[kind]()
+"""
+
+    destination_code = """\
+import enum
+
+class MessageKind(enum.StrEnum):
+    ASK = "ask"
+    REPLY = "reply"
+
+def handle_message(kind):
+    if kind == MessageKind.ASK:
+        return "ask"
+    return "reply"
+"""
+
+    # Global assignments are now inserted AFTER class/function definitions
+    # to ensure they can reference classes defined in the module
+    expected = """\
+import enum
+
+class MessageKind(enum.StrEnum):
+    ASK = "ask"
+    REPLY = "reply"
+
+def handle_message(kind):
+    if kind == MessageKind.ASK:
+        return "ask"
+    return "reply"
+
+_MESSAGE_HANDLERS = {
+    MessageKind.ASK: lambda: "ask handler",
+    MessageKind.REPLY: lambda: "reply handler",
+}
 """
 
     result = add_global_assignments(source_code, destination_code)