diff --git a/crates/oxide_vm/src/vm_dispatch_ctrl.rs b/crates/oxide_vm/src/vm_dispatch_ctrl.rs
index d5308ee..273971e 100644
--- a/crates/oxide_vm/src/vm_dispatch_ctrl.rs
+++ b/crates/oxide_vm/src/vm_dispatch_ctrl.rs
@@ -350,7 +350,14 @@ impl Vm {
     /// 读取 BREAK/CONTINUE/RETURN 的 ext 字逃出计数（低 16 位 for-of，高 16 位
     /// for-in）。调用时机：主循环已把 pc 推进到 ext 字位置；两条跳转/返回路径
     /// 都会覆盖 pc，此处无需再推进。
+    ///
+    /// # 边界与前提
+    /// - 手工构造的 IR 可能让 RETURN/BREAK/CONTINUE 落在末位且无 ext 字（pc == len），
+    ///   此时按 (0, 0) 处理：无迭代器逃出，语义正确。
     fn read_escape_counts(&self) -> (usize, usize) {
+        if self.pc >= self.bytecode.len() {
+            return (0, 0);
+        }
         let packed = self.bytecode[self.pc];
         ((packed & 0xFFFF) as usize, (packed >> 16) as usize)
     }
diff --git a/crates/oxide_vm/tests/spill_stack_tests.rs b/crates/oxide_vm/tests/spill_stack_tests.rs
index ef7929f..58c1161 100644
--- a/crates/oxide_vm/tests/spill_stack_tests.rs
+++ b/crates/oxide_vm/tests/spill_stack_tests.rs
@@ -62,10 +62,7 @@ fn spill_unspill_roundtrip() {
 #[test]
 fn frame_boundary_parent_spill_survives_call() {
     let child = int_module(
-        vec![
-            Inst::load_const(Operand::Reg(3), 0),
-            Inst::new(OpCode::RETURN, Operand::Reg(3), Operand::None, Operand::None),
-        ],
+        vec![Inst::load_const(Operand::Reg(3), 0), Inst::ret(Operand::Reg(3), 0, 0)],
         99,
         4,
         Vec::new(),
@@ -90,7 +87,7 @@ fn nested_call_both_spill() {
         vec![
             Inst::load_const(Operand::Reg(3), 0),
             Inst::inst_spill(Operand::Reg(3), 0),
-            Inst::new(OpCode::RETURN, Operand::Reg(3), Operand::None, Operand::None),
+            Inst::ret(Operand::Reg(3), 0, 0),
         ],
         99,
         4,