diff --git a/App/lib/core/Gen/StructGenMixin.vp b/App/lib/core/Gen/StructGenMixin.vp
index 73b6d07..d76d16e 100644
--- a/App/lib/core/Gen/StructGenMixin.vp
+++ b/App/lib/core/Gen/StructGenMixin.vp
@@ -346,6 +346,12 @@ class StructGenMixin:
             fe.DefaultVal = default_val
 
         struct_entry.FieldCount = idx + 1
+        # [ADF-DIAG] 确认字段表实际注册内容（定位 Thread.arg 缺失/索引错位）
+        dbg_adf: str = fname_pool.alloc(192)
+        if dbg_adf is not None:
+            viperlib.snprintf(dbg_adf, 192, "[ADF] struct=%s field=%s idx=%d\n",
+                              struct_entry.Name, field_name, idx)
+            stdio.printf("%s", dbg_adf)
         return idx
 
     def _deep_copy_default_ast(self, pool: memhub.MemBuddy | t.CPtr,