diff --git a/Cargo.lock b/Cargo.lock
index 3ab71678..53c0b2c6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1095,7 +1095,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_builtins"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "chrono",
  "fast-float",
@@ -1120,7 +1120,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_bytecode"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "num-bigint",
  "oxide_log",
@@ -1128,7 +1128,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cfg"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_emit",
@@ -1139,7 +1139,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cli"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "ansi_term",
  "bumpalo",
@@ -1159,7 +1159,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_code_cache"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "lru",
  "oxide_bytecode",
@@ -1168,7 +1168,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_compiler"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1187,7 +1187,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_dce"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1201,7 +1201,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_emit"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "num-bigint",
  "oxc_allocator",
@@ -1216,7 +1216,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_ir"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_log",
@@ -1225,7 +1225,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_kernel"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "bumpalo",
  "dashmap",
@@ -1240,7 +1240,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_liveness"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1252,7 +1252,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_log"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "tracing",
  "tracing-appender",
@@ -1261,7 +1261,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_parser"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxc_allocator",
  "oxc_ast",
@@ -1276,7 +1276,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_regalloc"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1292,7 +1292,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_runtime_api"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "num-bigint",
  "num-traits",
@@ -1304,7 +1304,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_test262"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "oxide_bytecode",
  "oxide_compiler",
@@ -1321,7 +1321,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_types"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "bumpalo",
  "hashbrown 0.14.5",
@@ -1333,7 +1333,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_vm"
-version = "0.8.20"
+version = "0.8.21"
 dependencies = [
  "bumpalo",
  "chrono",
diff --git a/Cargo.toml b/Cargo.toml
index 6dc272e9..dd82a3c1 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,7 +22,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.8.20"
+version = "0.8.21"
 edition = "2021"
 license = "MIT"
 rust-version = "1.80"
diff --git a/crates/oxide_emit/src/expr/assignment.rs b/crates/oxide_emit/src/expr/assignment.rs
index 086502d2..6e792f71 100644
--- a/crates/oxide_emit/src/expr/assignment.rs
+++ b/crates/oxide_emit/src/expr/assignment.rs
@@ -99,12 +99,15 @@ impl Emitter {
             }
             let is_tier = self.is_global_tier_name(ctx, name);
             let is_implicit = ctx.is_implicit_global_reg(var_reg);
+            let is_builtin = ctx.is_builtin(name) && !ctx.is_local_shadowing_builtin(name);
             if is_implicit && ctx.is_strict {
                 // 严格模式未声明复合写：未解析引用不可 put，值无关抛 ReferenceError。
                 return self.emit_strict_undeclared_write(name, ctx);
             }
             // RMW 前从全局对象属性取旧值：tier 名（顶层已声明 var）与未声明名同，
-            // 属性缺失按 undefined（GetBaseValue 语义，不抛）。
+            // 属性缺失按 undefined（GetBaseValue 语义，不抛）；已知 builtin 名（非局部
+            // 遮蔽）读 A 侧属性，属性缺失（delete 真删后）抛 ReferenceError，与裸读
+            // 同形——镜像槽不反映删除，无法自区分缺位与在位 undefined。
             if is_tier || is_implicit {
                 let key_idx = ctx.add_constant(Constant::String(name.to_string()));
                 ctx.inst(Inst::new(
@@ -113,6 +116,14 @@ impl Emitter {
                     Operand::Const(key_idx),
                     Operand::None,
                 ));
+            } else if is_builtin {
+                let key_idx = ctx.add_constant(Constant::String(name.to_string()));
+                ctx.inst(Inst::new(
+                    OpCode::LOAD_GLOBAL,
+                    Operand::Reg(var_reg),
+                    Operand::Const(key_idx),
+                    Operand::None,
+                ));
             }
             ctx.inst(Inst::new(op, Operand::Reg(var_reg), Operand::Reg(rhs), Operand::None));
             if is_tier {
@@ -389,7 +400,10 @@ impl Emitter {
                     } else {
                         let var_reg = ctx.lookup_or_global(name);
                         // 顶层已声明 var（tier）与未声明名同：旧值读前从全局对象
-                        // 属性取当前值，缺失按 undefined（不抛）。
+                        // 属性取当前值，缺失按 undefined（不抛）；已知 builtin 名
+                        // （非局部遮蔽）读 A 侧属性，属性缺失（delete 真删后）抛
+                        // ReferenceError，与裸读同形——镜像槽不反映删除，无法自
+                        // 区分缺位与在位 undefined。
                         if self.is_global_tier_name(ctx, name) || ctx.is_implicit_global_reg(var_reg) {
                             let key_idx = ctx.add_constant(Constant::String(name.to_string()));
                             ctx.inst(Inst::new(
@@ -398,6 +412,14 @@ impl Emitter {
                                 Operand::Const(key_idx),
                                 Operand::None,
                             ));
+                        } else if ctx.is_builtin(name) && !ctx.is_local_shadowing_builtin(name) {
+                            let key_idx = ctx.add_constant(Constant::String(name.to_string()));
+                            ctx.inst(Inst::new(
+                                OpCode::LOAD_GLOBAL,
+                                Operand::Reg(var_reg),
+                                Operand::Const(key_idx),
+                                Operand::None,
+                            ));
                         }
                         ctx.inst(Inst::new(
                             OpCode::LOAD_VAR,
diff --git a/crates/oxide_emit/src/expr/operator/mod.rs b/crates/oxide_emit/src/expr/operator/mod.rs
index 44101ce9..43528459 100644
--- a/crates/oxide_emit/src/expr/operator/mod.rs
+++ b/crates/oxide_emit/src/expr/operator/mod.rs
@@ -830,12 +830,16 @@ impl Emitter {
             }
             let is_tier = self.is_global_tier_name(ctx, name);
             let is_implicit = ctx.is_implicit_global_reg(var_reg);
+            let is_builtin = ctx.is_builtin(name) && !ctx.is_local_shadowing_builtin(name);
             if is_implicit && ctx.is_strict {
                 // 严格模式未声明更新写：值无关抛 ReferenceError。
                 return self.emit_strict_undeclared_write(name, ctx);
             }
             // RMW 前从全局对象属性取旧值：tier 名（顶层已声明 var）与未声明名同，
-            // 属性缺失按 undefined（update 旧值角落，GetBaseValue 语义，不抛）。
+            // 属性缺失按 undefined（update 旧值角落，GetBaseValue 语义，不抛）；
+            // 已知 builtin 名（非局部遮蔽）读 A 侧属性，属性缺失（delete 真删后）
+            // 抛 ReferenceError，与裸读同形——镜像槽不反映删除，无法自区分缺位
+            // 与在位 undefined。
             if is_tier || is_implicit {
                 let key_idx = ctx.add_constant(Constant::String(name.to_string()));
                 ctx.inst(Inst::new(
@@ -844,6 +848,14 @@ impl Emitter {
                     Operand::Const(key_idx),
                     Operand::None,
                 ));
+            } else if is_builtin {
+                let key_idx = ctx.add_constant(Constant::String(name.to_string()));
+                ctx.inst(Inst::new(
+                    OpCode::LOAD_GLOBAL,
+                    Operand::Reg(var_reg),
+                    Operand::Const(key_idx),
+                    Operand::None,
+                ));
             }
             let op = match (update.operator, update.prefix) {
                 (UpdateOperator::Increment, true) => OpCode::INC_PRE,
diff --git a/crates/oxide_vm/tests/delete_builtin_assign_tests.rs b/crates/oxide_vm/tests/delete_builtin_assign_tests.rs
new file mode 100644
index 00000000..e0e70e77
--- /dev/null
+++ b/crates/oxide_vm/tests/delete_builtin_assign_tests.rs
@@ -0,0 +1,187 @@
+//! delete 已知 builtin 名后的复合/逻辑赋值与 update 表达式 LHS 旧值读：
+//! 旧值读须经 A 侧全局对象属性在位判定，缺位（delete 真删后）抛
+//! ReferenceError，与裸读同形；在位时语义不变（A 侧读 + 写回）。
+//!
+//! 镜像槽无法自区分「A 侧缺位」与「A 侧在位值 undefined」（两者槽值皆
+//! undefined），delete 真删后旧值读走镜像槽会不抛且以计算值复活属性。
+//! 本面只改旧值读路由（三读点前插 LOAD_GLOBAL），写回路径零改动。
+
+use std::sync::Arc;
+
+use oxide_compiler::compiler::Compiler;
+use oxide_parser::Allocator;
+use oxide_types::value::JsValue;
+use oxide_vm::vm::Vm;
+
+fn eval_js(source: &str) -> Result<(Vm, JsValue), String> {
+    let allocator = Allocator::default();
+    let program = oxide_parser::parse(&allocator, source).map_err(|e| format!("parse: {e:?}"))?;
+    let module = Arc::new(Compiler::new().compile(&program).map_err(|e| format!("compile: {e}"))?);
+    let mut vm = Vm::new();
+    let val = vm.run(&module)?;
+    Ok((vm, val))
+}
+
+fn eval_str(source: &str) -> Result<String, String> {
+    let (vm, val) = eval_js(source)?;
+    Ok(vm.lookup_str(val).unwrap_or_else(|| format!("{val:?}")))
+}
+
+fn eval_truthy(source: &str) {
+    let (_vm, val) = eval_js(source).expect("run");
+    assert!(val.is_bool() && val.as_bool(), "expected true, got: {val:?}\nsource: {source}");
+}
+
+/// 删后 LHS 旧值读抛 ReferenceError 钉：运行期错误文本须含种类与名字。
+fn expect_re(source: &str, name: &str) {
+    let err = match eval_js(source) {
+        Err(e) => e,
+        Ok(_) => panic!("expected ReferenceError, got ok: {source}"),
+    };
+    let lower = err.to_lowercase();
+    assert!(lower.contains("referenceerror"), "expected ReferenceError, got: {err}\nsource: {source}");
+    assert!(lower.contains(name), "expected name in message, got: {err}\nsource: {source}");
+}
+
+// ── 红族：删后 LHS 旧值读抛 ReferenceError（修前不抛且以计算值复活属性）──
+
+// 复合主形态：顶层 delete 后复合赋值旧值读。
+#[test]
+fn delete_array_compound_add_reference_error() {
+    expect_re("delete Array; Array += 1", "array");
+}
+
+// 复合换算符：减。
+#[test]
+fn delete_array_compound_sub_reference_error() {
+    expect_re("delete Array; Array -= 1", "array");
+}
+
+// 复合换算符：乘。
+#[test]
+fn delete_array_compound_mul_reference_error() {
+    expect_re("delete Array; Array *= 2", "array");
+}
+
+// 逻辑主形态：||= 旧值读。
+#[test]
+fn delete_array_logical_or_reference_error() {
+    expect_re("delete Array; Array ||= 2", "array");
+}
+
+// 逻辑短路面：&&= 旧值读（短路测试前抛）。
+#[test]
+fn delete_array_logical_and_reference_error() {
+    expect_re("delete Array; Array &&= 2", "array");
+}
+
+// 逻辑空值面：??= 旧值读。
+#[test]
+fn delete_array_logical_nullish_reference_error() {
+    expect_re("delete Array; Array ??= 2", "array");
+}
+
+// update 前缀主形态。
+#[test]
+fn delete_array_update_prefix_increment_reference_error() {
+    expect_re("delete Array; Array++", "array");
+}
+
+// update 前缀换算符：递减。
+#[test]
+fn delete_array_update_prefix_decrement_reference_error() {
+    expect_re("delete Array; --Array", "array");
+}
+
+// update 后缀面。
+#[test]
+fn delete_array_update_postfix_reference_error() {
+    expect_re("delete Array; Array--", "array");
+}
+
+// 换名族：Promise 单名复合。
+#[test]
+fn delete_promise_compound_reference_error() {
+    expect_re("delete Promise; Promise += 1", "promise");
+}
+
+// 帧读面：delete 在外层，嵌套函数内复合赋值旧值读缺失。
+#[test]
+fn delete_array_nested_fn_compound_reference_error() {
+    expect_re("delete Array; (function(){Array += 1})()", "array");
+}
+
+// 成员复合守卫钉：成员面旧值读走对象属性（非镜像槽），零涉本面；
+// 基引用 Math 裸读经 221.1 路由抛 ReferenceError，成员复合路径不改变该抛点。
+#[test]
+fn delete_math_member_compound_base_read_reference_error() {
+    expect_re("delete Math; Math.max += 1", "math");
+}
+
+// with 复合回退面：with 对象无该属性时回退静态复合路径，旧值读缺失抛。
+#[test]
+fn delete_array_with_compound_fallback_reference_error() {
+    expect_re("delete Array; with(globalThis){Array += 1}", "array");
+}
+
+// with update 回退面：同复合回退面，update 表达式。
+#[test]
+fn delete_array_with_update_fallback_reference_error() {
+    expect_re("delete Array; with(globalThis){Array++}", "array");
+}
+
+// with 逻辑赋值无对象回退：with 体自由标识符逻辑赋值走静态路径，旧值读缺失抛。
+#[test]
+fn delete_array_with_logical_fallback_reference_error() {
+    expect_re("delete Array; with({x: 1}){Array ||= 2}", "array");
+}
+
+// ── 绿族：修后须保真 ──
+
+// 未删在位复合：A 侧读 + 写回，语义不变。
+#[test]
+fn builtin_compound_add_present_value() {
+    assert_eq!(eval_str("Array = 1; Array += 1; String(Array)").unwrap(), "2");
+}
+
+// 局部 var 零涉：非 builtin 名复合赋值。
+#[test]
+fn local_var_compound_add_value() {
+    assert_eq!(eval_str("var x = 1; x += 1; String(x)").unwrap(), "2");
+}
+
+// 遮蔽守卫：局部 var Array 遮蔽 builtin 槽，复合走局部槽。
+#[test]
+fn local_var_shadow_array_compound_value() {
+    assert_eq!(eval_str("function g(){var Array=1; Array += 1; return Array}; String(g())").unwrap(), "2",);
+}
+
+// 只读三常量零涉：c:false 拒删保值，复合旧值读不抛。
+#[test]
+fn delete_nan_compound_no_throw() {
+    eval_truthy("delete NaN === false && Number.isNaN(NaN += 1)");
+}
+
+// 删后重写再复合：A 侧在位，旧值读见新值。
+#[test]
+fn delete_array_rewrite_compound_value() {
+    assert_eq!(eval_str("delete Array; Array = 42; Array += 1; String(Array)").unwrap(), "43");
+}
+
+// 成员面零涉：对象属性 delete 后成员复合不抛（GetBaseValue 缺位按 undefined）。
+#[test]
+fn member_compound_after_delete_no_throw() {
+    eval_truthy("var obj = {p: 1}; delete obj.p; obj.p += 1; Number.isNaN(obj.p)");
+}
+
+// 221.1 保真：typeof 不抛。
+#[test]
+fn delete_array_typeof_undefined() {
+    assert_eq!(eval_str("delete Array; typeof Array").unwrap(), "undefined");
+}
+
+// 221.1 保真：裸读抛 ReferenceError。
+#[test]
+fn delete_array_bare_read_reference_error() {
+    expect_re("delete Array; Array", "array");
+}