diff --git a/includes/_withcontent.vp b/includes/_withcontent.vp
index 01c82e4..6036313 100644
--- a/includes/_withcontent.vp
+++ b/includes/_withcontent.vp
@@ -26,7 +26,12 @@ _tls_index: ULONG = 0
 def _init_tls():
     """Initialize TLS index (executes once; subsequent calls are skipped)."""
     global _tls_index
-    _tls_index = TlsAlloc()
+    # TPV 未实现 @t.TLS 的"首次执行"守卫（函数每次调用都执行体），
+    # 不加守卫会导致每次 _get_stack 都 TlsAlloc 新索引 → 每次拿到新
+    # 空栈 → push/find 各用各的栈，provider 永远匹配失败。_tls_index
+    # 初始为 0（TlsAlloc 成功不会返回 0），以此判重即等价 TLS 语义。
+    if _tls_index == 0:
+        _tls_index = TlsAlloc()
 
 
 def _get_stack() -> _ProviderStack | t.CPtr: