diff --git a/App/lib/core/Gen/Call/CallGenDispatch.vp b/App/lib/core/Gen/Call/CallGenDispatch.vp
index 844738a..c064e9b 100644
--- a/App/lib/core/Gen/Call/CallGenDispatch.vp
+++ b/App/lib/core/Gen/Call/CallGenDispatch.vp
@@ -337,17 +337,26 @@ novirtual class CallGenDispatch(CallGenBase.CallGenBase):
 
     def _tc_h4_type_casts(self, pool: memhub.MemBuddy*, builder: mlirlite.IRBuilder*, mod: mlirlite.LLVMModule*, cl: ast.Call*, funcs_ptr: rawptr, func_count: int, trans: HT.Translator*, func_name: str, cargs: list[ast.AST*]*, can: sizet) -> mlirlite.Value*:
         """Builtin / typedef type casts; returns None when unmatched."""
-        # Module-qualified typedef cast (posix.mode_t(mode), win32.win32base.HANDLE(v), ...): func is
-        # Attribute(Name(module), typedef); non-typedef names still go to the module function call.
+        # Module-qualified typedef cast (posix.mode_t(mode), win32.win32base.LPCWSTR(v), ...): the
+        # callee is Attribute(<module path>, typedef); non-typedef names still go to the module call.
         if cl.func is not None and cl.func.kind() == ast.ASTKind.Attribute:
             mt_at: ast.Attribute* = ast.Attribute*(cl.func)
-            if mt_at.value is not None and mt_at.value.kind() == ast.ASTKind.Name:
-                mt_mod_nm: ast.Name* = ast.Name*(mt_at.value)
-                if mt_mod_nm.id is not None:
+            if mt_at.attr is not None:
+                # Module path supports both `mod.T` and nested `pkg.mod.T`.
+                mt_mod_path: str = None
+                if mt_at.value is not None and mt_at.value.kind() == ast.ASTKind.Name:
+                    mt_mod_nm: ast.Name* = ast.Name*(mt_at.value)
+                    mt_mod_path = mt_mod_nm.id
+                elif mt_at.value is not None and mt_at.value.kind() == ast.ASTKind.Attribute:
+                    mt_mod_path = self.Gen.ExprGenAttr._attr_module_path_str(pool, mt_at.value)
+                if mt_mod_path is not None:
                     mod_td_ty: mlirlite.LLVMType* = self.Gen.TypeGenResolve.map_builtin_type(pool, func_name)
                     if mod_td_ty is None:
                         mod_td_str: str = self.Gen.TypeGenCType.lookup_ctypedef(func_name)
-                        if mod_td_str is not None and self.Gen.TypeGenCType.is_ctypedef_found() != 0:
+                        if mod_td_str is None or self.Gen.TypeGenCType.is_ctypedef_found() == 0:
+                            # Library typedef closure may not be injected yet: scan the module source.
+                            mod_td_str = self.Gen.TypeGenResolve._lookup_library_typedef(pool, mt_mod_path, func_name)
+                        if mod_td_str is not None:
                             mod_td_ast: ast.AST* = self.Gen.TypeGenResolve._parse_type_string(pool, mod_td_str, 0)
                             if mod_td_ast is not None:
                                 mod_imp_td: str = None