diff --git a/includes/ast/parser.vp b/includes/ast/parser.vp
index 462c9b8..f1136a1 100644
--- a/includes/ast/parser.vp
+++ b/includes/ast/parser.vp
@@ -2,6 +2,8 @@ import t, c
 from stdint import *
 import memhub
 import string
+import stdio
+import stdlib
 from .tokens import (Token, TokenType, Keyword, TokOp)
 from .base import (
     AST, ASTCtx, ASTKind, OpKind, ASTFlag,
@@ -165,7 +167,39 @@ def _new_const_int(pool: memhub.MemManager | t.CPtr, val: t.CInt64T,
 
 def _new_const_float(pool: memhub.MemManager | t.CPtr, val: t.CDouble,
                      lineno: t.CInt, col: t.CInt) -> AST | t.CPtr:
-    return Constant(pool, CONST_FLOAT, 0, val, None, lineno, col)
+    global _g_dbg_pts, _g_dbg_vals, _g_dbg_cnt
+    new_c: Constant | t.CPtr = Constant(pool, CONST_FLOAT, 0, val, None, lineno, col)
+    # OVW-DBG: 检查之前构造的浮点节点是否已被覆写（定位覆写者）
+    if _g_dbg_cnt > 0 and _g_dbg_pts is not None and _g_dbg_vals is not None:
+        chk: t.CSizeT = 0
+        while chk < _g_dbg_cnt:
+            old_ptr: t.CUInt64T = _g_dbg_pts[chk]
+            if old_ptr != 0:
+                old_val: t.CDouble = _g_dbg_vals[chk]
+                old_c: Constant | t.CPtr = (Constant | t.CPtr)(t.CVoid(old_ptr, t.CPtr))
+                if old_c.float_val != old_val:
+                    stdio.printf("[OVW-DBG] 构造新字面量 val=%.17g 后，之前节点 ptr=%p 的 float_val 从 %.17g 变 %.17g\n",
+                                 val, t.CUInt64T(old_ptr), old_val, old_c.float_val)
+                    _g_dbg_pts[chk] = 0
+            chk += 1
+    # 记录当前节点
+    if _g_dbg_pts is None:
+        _g_dbg_pts = stdlib.malloc(512 * 8)
+        _g_dbg_vals = stdlib.malloc(512 * 8)
+    if _g_dbg_cnt < 512 and _g_dbg_pts is not None and _g_dbg_vals is not None:
+        _g_dbg_pts[_g_dbg_cnt] = t.CUInt64T(new_c)
+        _g_dbg_vals[_g_dbg_cnt] = val
+        _g_dbg_cnt += 1
+    # NEWF-DBG: 打印浮点常量构造值+节点指针+存储后读回（定位浮点 CDefine 值错误）
+    stdio.printf("[NEWF-DBG] val=%.17g ptr=%p readback=%.17g int_val=%lld\n",
+                 val, t.CSizeT(new_c), new_c.float_val, new_c.int_val)
+    return new_c
+
+
+# OVW-DBG: 浮点节点监控表（stdlib 分配，避免污染 pool）
+_g_dbg_pts: t.CUInt64T | t.CPtr = None
+_g_dbg_vals: t.CDouble | t.CPtr = None
+_g_dbg_cnt: int = 0
 
 
 def _new_const_str(pool: memhub.MemManager | t.CPtr, val: str,
diff --git a/includes/string.vp b/includes/string.vp
index 6ad1adb..e44a386 100644
--- a/includes/string.vp
+++ b/includes/string.vp
@@ -365,6 +365,10 @@ def atof(src: str) -> t.CDouble:
         while exp < 0:
             result = result / 10.0
             exp += 1
+    # ATOF-DBG: 打印长浮点字面量解析过程（定位浮点 CDefine 值错误）
+    if src is not None and strlen(src) >= 12:
+        stdio.printf("[ATOF-DBG] src=%s int=%.17g frac=%.17g div=%.17g result=%.17g\n",
+                     src, int_part, frac_part, frac_div, result)
     return result
 
 def split(s: str, delim: str, result: t.CArray[str]) -> int: