feat: CustomEvent 载荷盒加 GC 加构造器加原型

Cargo.lock

@@ -1160,7 +1160,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_builtins"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "chrono",
  "fast-float",
@@ -1185,7 +1185,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_bytecode"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "num-bigint",
  "oxide_log",
@@ -1193,7 +1193,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cfg"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_emit",
@@ -1204,7 +1204,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cli"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "ansi_term",
  "bumpalo",
@@ -1227,7 +1227,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_code_cache"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "lru",
  "oxide_bytecode",
@@ -1236,7 +1236,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_compiler"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1256,7 +1256,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_dce"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1270,7 +1270,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_emit"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "num-bigint",
  "oxc_allocator",
@@ -1285,7 +1285,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_engine"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_compiler",
@@ -1297,7 +1297,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_ir"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_log",
@@ -1306,7 +1306,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_kernel"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "bumpalo",
  "dashmap",
@@ -1320,7 +1320,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_liveness"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1332,7 +1332,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_log"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "tracing",
  "tracing-appender",
@@ -1341,7 +1341,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_parser"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxc_allocator",
  "oxc_ast",
@@ -1356,7 +1356,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_regalloc"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1372,7 +1372,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_runtime_api"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "num-bigint",
  "num-traits",
@@ -1385,7 +1385,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_test262"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "oxide_bytecode",
  "oxide_compiler",
@@ -1403,7 +1403,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_types"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "bumpalo",
  "dashmap",
@@ -1416,7 +1416,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_vm"
-version = "0.14.13"
+version = "0.14.14"
 dependencies = [
  "bumpalo",
  "chrono",

Cargo.toml

@@ -23,7 +23,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.14.13"
+version = "0.14.14"
 edition = "2021"
 license = "MIT"
 rust-version = "1.80"

crates/oxide_builtins/src/event.rs

@@ -1,16 +1,17 @@
-//! Event 基类与 MessageEvent / ErrorEvent 派生类行为面：`Event` 构造器
+//! Event 基类与 MessageEvent / ErrorEvent / CustomEvent 派生类行为面：
-//! （`new Event(type, init)`）、原型 getter（type / target / currentTarget /
+//! `Event` 构造器（`new Event(type, init)`）、原型 getter（type / target /
-//! eventPhase / isTrusted / bubbles / cancelable / defaultPrevented /
+//! currentTarget / eventPhase / isTrusted / bubbles / cancelable /
-//! composed）与原型方法（preventDefault / stopPropagation /
+//! defaultPrevented / composed）与原型方法（preventDefault / stopPropagation /
 //! stopImmediatePropagation / composedPath）；`MessageEvent` 构造器
 //! （`new MessageEvent(type, init)`）与原型 getter（data / origin / lastEpoch /
 //! source / ports）；`ErrorEvent` 构造器（`new ErrorEvent(type, init)`）与
-//! 原型 getter（message / filename / lineno / colno / error）。
+//! 原型 getter（message / filename / lineno / colno / error）；`CustomEvent`
+//! 构造器（`new CustomEvent(type, init)`）与原型 getter（detail）。
 //!
 //! 事件载荷盒（type 串与九项状态位，MessageEvent 加 data / origin /
 //! lastEpoch / source / ports 五字段，ErrorEvent 加 message / filename /
-//! lineno / colno / error 五字段）存于对象 `native_fn` 槽，向 GC 家族表
+//! lineno / colno / error 五字段，CustomEvent 加 detail 一字段）存于对象
-//! 暴露 edges/size/drop 三自由函数。
+//! `native_fn` 槽，向 GC 家族表暴露 edges/size/drop 三自由函数。
 
 use std::mem;
 
@@ -73,6 +74,18 @@ struct ErrorEventInner {
     error: JsValue,
 }
 
+/// CustomEvent 载荷盒：事件基类字段（`EventInner` 嵌入，位于偏移 0）加详情
+/// 字段（detail）。存于对象 `native_fn` 槽（`Box::into_raw`，realm 局部
+/// 单线程）。
+///
+/// `#[repr(C)]` 固定 `base` 位于偏移 0：派生类盒指针转基类指针读首字段依赖该
+/// 偏移稳定（与 `EventInner` 同型约束）。
+#[repr(C)]
+struct CustomEventInner {
+    base: EventInner,
+    detail: JsValue,
+}
+
 /// 是否事件系对象（Event / MessageEvent / ErrorEvent / CustomEvent 四标签）。
 pub fn is_event_family_obj(obj: &JsObject) -> bool {
     matches!(
@@ -1233,3 +1246,198 @@ pub fn error_event_error_getter<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeRes
     };
     NativeResult::Ok(inner.error)
 }
+
+// —— CustomEvent 派生类 ——
+
+/// 取 CustomEvent 载荷盒指针：仅 CustomEvent 标签对象返回 `Some`，其余标签
+/// 返回 `None`。
+fn custom_event_payload_ptr(obj: &JsObject) -> Option<*mut CustomEventInner> {
+    if obj.type_tag != JsObject::OBJ_TYPE_CUSTOM_EVENT {
+        return None;
+    }
+    obj.native_fn().map(|ptr| ptr.as_ptr() as *mut CustomEventInner)
+}
+
+/// 收集 CustomEvent 的引用边（基类 type / target / current_target 边加
+/// detail 边）。
+///
+/// `target` / `current_target` 空窗口（构造期回填之前）为 null，边函数自守，
+/// 语义自含。
+pub fn custom_event_native_edges(obj: &JsObject) -> Vec<JsValue> {
+    let Some(ptr) = custom_event_payload_ptr(obj) else {
+        return Vec::new();
+    };
+    if ptr.is_null() {
+        return Vec::new();
+    }
+    // SAFETY: ptr 指向有效载荷盒（槽位仅构造期写入、释放时置空），只读字段。
+    let inner = unsafe { &*ptr };
+    let mut edges = vec![inner.base.r#type, inner.base.target, inner.base.current_target];
+    edges.push(inner.detail);
+    edges
+}
+
+/// 只读核算 CustomEvent 载荷盒字节（不释放）。
+pub fn custom_event_native_size(obj: &JsObject) -> u64 {
+    let Some(ptr) = custom_event_payload_ptr(obj) else {
+        return 0;
+    };
+    if ptr.is_null() {
+        return 0;
+    }
+    mem::size_of::<CustomEventInner>() as u64
+}
+
+/// 释放 CustomEvent 载荷盒（`Box<CustomEventInner>`），返回释放字节数。
+///
+/// 盒 drop 时基类字段与 detail 的 JsValue 边随盒释放（GC 已判定死对象）；
+/// 槽置空保证重复调用零释放（幂等）。
+pub fn drop_custom_event_native(obj: &mut JsObject) -> u64 {
+    let bytes = custom_event_native_size(obj);
+    if bytes == 0 {
+        return 0;
+    }
+    let Some(ptr) = custom_event_payload_ptr(obj) else {
+        return 0;
+    };
+    // SAFETY: ptr 非空（custom_event_native_size 已验证），Box::from_raw 恰好
+    // 释放一次。
+    unsafe {
+        drop(Box::from_raw(ptr));
+    }
+    obj.set_native_fn(None);
+    bytes
+}
+
+/// CustomEvent 构造器：`new CustomEvent(type, init)`。
+///
+/// # 步骤
+/// 1. 非构造形态（`!constructing_native`）抛 TypeError（HTML 规范只有
+///    [[Construct]]，无 [[Call]]）
+/// 2. type 经完整 ToString 转串；空串抛 SyntaxError
+/// 3. init 字典读 detail（缺省 null）
+/// 4. 建载荷盒入 receiver 的 `native_fn` 槽，置 type_tag
+/// 5. 返回 receiver
+///
+/// # 边界与前提
+/// - receiver（`args[0]`）是 VM 按构造器 prototype 新分配的对象，proto 已
+///   指向 %CustomEvent.prototype%；
+/// - init 缺省（undefined）或非对象时 detail 取缺省。
+///
+/// # 副作用
+/// - receiver 的 `native_fn` 槽写入载荷盒、`type_tag` 置 CustomEvent 标签。
+pub fn custom_event_constructor<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
+    if !vm.constructing_native() {
+        return NativeResult::Err(crate::error::create_type_error(vm, "CustomEvent constructor requires new"));
+    }
+
+    let this_val = vm.reg(args[0]);
+    if !this_val.is_object() {
+        return NativeResult::Err(crate::error::create_type_error(vm, "CustomEvent constructor requires new"));
+    }
+
+    // type 经完整 ToString 转串（对象经 ToPrimitive，Symbol 抛 TypeError）。
+    let type_val = if args.len() > 1 { vm.reg(args[1]) } else { JsValue::undefined() };
+    let type_str = match oxide_runtime_api::to_string_full(type_val, vm) {
+        Ok(s) => s,
+        Err(_) => {
+            if let Some(exc) = vm.take_uncaught_value() {
+                return NativeResult::Err(exc);
+            }
+            return NativeResult::Err(crate::error::create_type_error(vm, "Cannot convert value to a string"));
+        }
+    };
+    if type_str.is_empty() {
+        return NativeResult::Err(crate::error::create_syntax_error(vm, "The provided type is empty"));
+    }
+
+    // init 字典读 detail（缺省或非对象时取缺省）。
+    let mut detail = JsValue::null();
+    if args.len() > 2 {
+        let init_val = vm.reg(args[2]);
+        if init_val.is_object() {
+            let init_ptr = init_val.as_js_object_ptr();
+            // SAFETY: init_val 已确认是对象值，借用即时消费。
+            let init_obj = unsafe { &*init_ptr };
+            let si = vm.perm_intern("detail");
+            match vm.ordinary_get(init_obj, si, init_val) {
+                Ok(v) => {
+                    if !v.is_undefined() {
+                        detail = v;
+                    }
+                }
+                Err(_) => {
+                    if let Some(exc) = vm.take_uncaught_value() {
+                        return NativeResult::Err(exc);
+                    }
+                    return NativeResult::Err(crate::error::create_type_error(
+                        vm,
+                        "CustomEvent init property getter failed",
+                    ));
+                }
+            }
+        }
+    }
+
+    // 建载荷盒入 receiver 的 native_fn 槽，置 CustomEvent 标签。
+    let type_js = vm.new_string(&type_str);
+    let inner = Box::into_raw(Box::new(CustomEventInner {
+        base: EventInner {
+            r#type: type_js,
+            target: JsValue::null(),
+            current_target: JsValue::null(),
+            event_phase: 0,
+            is_trusted: false,
+            bubbles: false,
+            cancelable: false,
+            default_prevented: false,
+            propagation_stopped: false,
+            immediate_stopped: false,
+            composed: false,
+        },
+        detail,
+    }));
+    // SAFETY: receiver 不可调用，native_fn 存不透明 `Box<CustomEventInner>`
+    // 指针，与 ArrayBuffer / RegExp 的类型化存储模式一致。
+    let obj = unsafe { &mut *this_val.as_js_object_ptr() };
+    obj.type_tag = JsObject::OBJ_TYPE_CUSTOM_EVENT;
+    obj.set_native_fn(Some(unsafe { NativeFnPtr::from_raw(inner as *const ()) }));
+    NativeResult::Ok(this_val)
+}
+
+/// 解析 this 为 CustomEvent 载荷盒共享引用：非 CustomEvent 对象或无载荷盒
+/// 返回 None。
+///
+/// # 注意事项
+/// 返回引用按 `'a` 声称为存活，实际存活至载荷盒被 GC 释放；调用方须在无 GC
+/// 窗口的单 native 函数内消费，不得跨用户调用窗口持有。
+fn custom_event_inner_of<'a>(this_val: JsValue) -> Option<&'a CustomEventInner> {
+    if !this_val.is_object() {
+        return None;
+    }
+    let obj_ptr = this_val.as_js_object_ptr();
+    if obj_ptr.is_null() {
+        return None;
+    }
+    // SAFETY: this_val 已确认是对象值，obj_ptr 指向合法 JsObject。
+    let obj = unsafe { &*obj_ptr };
+    let box_ptr = custom_event_payload_ptr(obj)?;
+    if box_ptr.is_null() {
+        return None;
+    }
+    // SAFETY: box_ptr 指向有效载荷盒（构造期写入、释放时置空）；'a 存活由
+    // 调用方「无 GC 窗口内消费」约定保证。
+    Some(unsafe { &*box_ptr })
+}
+
+/// `CustomEvent.prototype.detail`：返回事件详情（缺省为 null）。
+pub fn custom_event_detail_getter<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
+    let this_val = vm.reg(if args.is_empty() { 0 } else { args[0] });
+    let Some(inner) = custom_event_inner_of(this_val) else {
+        return NativeResult::Err(crate::error::create_type_error(
+            vm,
+            "CustomEvent.prototype.detail getter called on non-CustomEvent object",
+        ));
+    };
+    NativeResult::Ok(inner.detail)
+}

crates/oxide_vm/src/bindings/bind_event.rs

@@ -3,10 +3,9 @@
 //! 就地填充 `message_event_constructor` / `message_event_proto` 两枚 P 字段
 //! 占位（构造器本体与原型 getter），并绑全局 `MessageEvent`；就地填充
 //! `error_event_constructor` / `error_event_proto` 两枚 P 字段占位（构造器
-//! 本体与原型 getter），并绑全局 `ErrorEvent`。
+//! 本体与原型 getter），并绑全局 `ErrorEvent`；就地填充
-//!
+//! `custom_event_constructor` / `custom_event_proto` 两枚 P 字段占位（构造器
-//! 九枚 P 字段中其余两枚（CustomEvent 一对）由后续子任务就地填充，本函数
+//! 本体与原型 getter），并绑全局 `CustomEvent`。
-//! 不读不写。
 
 use std::sync::Arc;
 
@@ -16,12 +15,14 @@ use oxide_kernel::kernel::{KernelCore, KernelSession};
 use oxide_types::object::{JsObject, PropAttributes};
 use oxide_types::value::JsValue;
 
-/// 把 Event / MessageEvent / ErrorEvent 构造器及原型方法绑定到 global。
+/// 把 Event / MessageEvent / ErrorEvent / CustomEvent 构造器及原型方法绑定到
+/// global。
 ///
 /// `event_constructor` / `event_proto`、`message_event_constructor` /
-/// `message_event_proto` 与 `error_event_constructor` / `error_event_proto`
+/// `message_event_proto`、`error_event_constructor` / `error_event_proto` 与
-/// 六枚 P 字段是空对象占位，本函数就地填充（不新建对象——P 字段本身就是
+/// `custom_event_constructor` / `custom_event_proto` 八枚 P 字段是空对象占位，
-/// 槽位，快照/脏检查/收尾枚举已覆盖）。
+/// 本函数就地填充（不新建对象——P 字段本身就是槽位，快照/脏检查/收尾枚举已
+/// 覆盖）。
 ///
 /// # 幂等
 /// 本函数从三条路径到达：`init_kernel_builtins`（占位是空对象）、
@@ -314,6 +315,69 @@ pub fn bind_event(core: &Arc<KernelCore>, session: &KernelSession, global: &mut
         }
     }
 
+    // ---- 填 CustomEvent 构造器与原型占位 ----
+    let ce_ctor_ptr = world.custom_event_constructor.as_ptr() as *mut JsObject;
+    let ce_ctor = unsafe { &mut *ce_ctor_ptr };
+    let ce_proto_ptr = world.custom_event_proto.as_ptr() as *mut JsObject;
+    let ce_proto = unsafe { &mut *ce_proto_ptr };
+
+    // 构造器：function 标志、prototype 槽、name 槽、[[Prototype]] →
+    // Function.prototype（幂等，裸写槽）。
+    ce_ctor.set_function(true);
+    if sh.lookup_position(ce_ctor.shape_id(), si_prototype).is_none() {
+        let shape = sh.make_shape(ce_ctor.shape_id(), si_prototype);
+        ce_ctor.set_shape_id(shape);
+        let pos = ce_ctor.push_prop(JsValue::from_js_object(ce_proto_ptr));
+        ce_ctor.set_data_meta(pos, PropAttributes::new(false, false, false));
+        ce_ctor.bump_generation();
+    }
+    if sh.lookup_position(ce_ctor.shape_id(), si_name).is_none() {
+        let shape = sh.make_shape(ce_ctor.shape_id(), si_name);
+        ce_ctor.set_shape_id(shape);
+        ce_ctor
+            .ensure_hash_props()
+            .push(JsValue::perm_string(sf.string_ptr(sf.intern("CustomEvent").0)));
+        let pos = ce_ctor.hash_props_vec().map_or(0, |v| v.len() as u32).saturating_sub(1);
+        ce_ctor.set_data_meta(pos, PropAttributes::new(false, false, true));
+        ce_ctor.bump_generation();
+    }
+    let _ = ce_ctor.set_proto(fn_proto_val);
+
+    configure_native_constructor(
+        ce_ctor,
+        oxide_builtins::event::custom_event_constructor::<crate::vm::Vm> as *const (),
+        2,
+    );
+    bind_constructor!(
+        core,
+        global,
+        "CustomEvent",
+        ce_ctor_ptr,
+        oxide_builtins::event::custom_event_constructor::<crate::vm::Vm>,
+        2,
+        hash: true
+    );
+
+    // 原型：constructor 槽、[[Prototype]] → Event.prototype、一个 getter
+    // （detail，先 lookup_position 守卫）。
+    if sh.lookup_position(ce_proto.shape_id(), si_constructor).is_none() {
+        let shape = sh.make_shape(ce_proto.shape_id(), si_constructor);
+        ce_proto.set_shape_id(shape);
+        let pos = ce_proto.push_prop(JsValue::from_js_object(ce_ctor_ptr));
+        ce_proto.set_data_meta(pos, PropAttributes::new(true, false, true));
+        ce_proto.bump_generation();
+    }
+    let _ = ce_proto.set_proto(event_proto_val);
+
+    let ce_getter_fns: [(&str, *const ()); 1] =
+        [("detail", oxide_builtins::event::custom_event_detail_getter::<crate::vm::Vm> as *const ())];
+    for (name, fn_ptr) in ce_getter_fns {
+        let si = sf.intern(name).0;
+        if sh.lookup_position(ce_proto.shape_id(), si).is_none() {
+            bind_accessor_getter(core, session, ce_proto, name, fn_ptr);
+        }
+    }
+
     // ---- 填 EventTarget 原型占位（无构造器，仅暴露原型与三方法）----
     // 幂等：三方法经 lookup_position 守卫，[[Prototype]] 裸写槽幂等。
     let et_proto_ptr = world.event_target_proto.as_ptr() as *mut JsObject;

crates/oxide_vm/src/bindings/mod.rs

@@ -26,8 +26,8 @@ pub mod bind_date;
 pub mod bind_disposable_stack;
 /// Error 家族构造器与原型的 native 方法绑定（含各子类型构造器创建）。
 pub mod bind_error;
-/// Event 体系绑定入口（Event / MessageEvent / ErrorEvent 构造器与原型就地
+/// Event 体系绑定入口（Event / MessageEvent / ErrorEvent / CustomEvent 构造器
-/// 填充，CustomEvent 一对由后续任务填充）。
+/// 与原型就地填充）。
 pub mod bind_event;
 /// Function 构造器与原型的 native 方法绑定。
 pub mod bind_function;

crates/oxide_vm/src/native_box_dispatch.rs

@@ -255,10 +255,10 @@ pub(crate) fn ops_for(family: NativeBoxFamily) -> NativeBoxOps {
             string_edges: None,
             cell_edges: None,
         },
-        // CustomEvent 载荷盒由后续子任务填充；本臂当前无引用边，仅 size/drop
+        // CustomEvent 派生类载荷盒：基类 type / target / current_target 边加
-        // 链消费。
+        // detail 边。
         NativeBoxFamily::CustomEvent => NativeBoxOps {
-            object_edges: None,
+            object_edges: Some(event::custom_event_native_edges),
             string_edges: None,
             cell_edges: None,
         },

crates/oxide_vm/src/session_gc.rs

@@ -135,6 +135,7 @@ impl SessionGc {
         bytes += event::event_native_size(obj);
         bytes += event::message_event_native_size(obj);
         bytes += event::error_event_native_size(obj);
+        bytes += event::custom_event_native_size(obj);
         bytes += crate::arguments_gc::arguments_native_size(obj);
 
         bytes
@@ -379,13 +380,13 @@ impl SessionGc {
             }
         }
         // 事件系载荷盒（Event / MessageEvent / ErrorEvent / CustomEvent）字符串
-        // 边标记：按标签取对应边函数；CustomEvent 载荷盒由后续子任务填充，
+        // 边标记：按标签取对应边函数。
-        // 当前取空边。
         if event::is_event_family_obj(obj) {
             let edges = match obj.type_tag {
                 JsObject::OBJ_TYPE_EVENT => event::event_native_edges(obj),
                 JsObject::OBJ_TYPE_MESSAGE_EVENT => event::message_event_native_edges(obj),
                 JsObject::OBJ_TYPE_ERROR_EVENT => event::error_event_native_edges(obj),
+                JsObject::OBJ_TYPE_CUSTOM_EVENT => event::custom_event_native_edges(obj),
                 _ => Vec::new(),
             };
             for value in edges {
@@ -596,6 +597,7 @@ impl SessionGc {
             freed_bytes += event::drop_event_native(obj);
             freed_bytes += event::drop_message_event_native(obj);
             freed_bytes += event::drop_error_event_native(obj);
+            freed_bytes += event::drop_custom_event_native(obj);
             freed_bytes += crate::arguments_gc::drop_arguments_native(obj);
 
             freed_bytes

crates/oxide_vm/tests/event_target_tests.rs

@@ -289,3 +289,48 @@ fn error_event_box_edge_survives_gc() {
     vm.collect_session_gc();
     assert_eq!(vm_eval(&mut vm, "globalThis.e.error.tag;"), "1");
 }
+
+/// CustomEvent 构造器：init 的 detail 经原型 getter 可读。
+#[test]
+fn custom_event_constructor_detail() {
+    assert_eq!(eval("new CustomEvent('x', { detail: { a: 1 } }).detail.a;"), "1");
+}
+
+/// CustomEvent 缺省字段：detail 为 null。
+#[test]
+fn custom_event_detail_defaults_null() {
+    assert_eq!(eval("new CustomEvent('x').detail === null;"), "true");
+}
+
+/// CustomEvent 原型链：instanceof CustomEvent 与 instanceof Event 均真，
+/// 原型双亲为 Event.prototype。
+#[test]
+fn custom_event_proto_chain() {
+    assert_eq!(
+        eval(
+            "var e = new CustomEvent('x'); \
+             e instanceof CustomEvent && e instanceof Event && \
+             Object.getPrototypeOf(e) === CustomEvent.prototype && \
+             Object.getPrototypeOf(CustomEvent.prototype) === Event.prototype;"
+        ),
+        "true"
+    );
+}
+
+/// CustomEvent 非构造形态抛 TypeError。
+#[test]
+fn custom_event_requires_new() {
+    assert_eq!(
+        eval("try { CustomEvent('x'); 'no-throw'; } catch (e) { e instanceof TypeError; }"),
+        "true"
+    );
+}
+
+/// CustomEvent 盒边 GC 保活：detail 字段引用对象经完整收集后仍存活。
+#[test]
+fn custom_event_box_edge_survives_gc() {
+    let mut vm = vm_with_script("globalThis.e = new CustomEvent('x', { detail: { a: 1 } });");
+    // 强制完整收集：detail 字段是盒内 GC 边，对象应保活。
+    vm.collect_session_gc();
+    assert_eq!(vm_eval(&mut vm, "globalThis.e.detail.a;"), "1");
+}