bun_runtime 0.1.2

// @trace REQ-ENG-011 [api:vm.createContext / vm.runInNewContext / vm.Script]
//! node:vm module — SpiderMonkey Realm-isolated sandbox implementation.
//!
//! ## Architecture (DEC-ENG-003)
//!
//! Each `vm.createContext(sandbox)` creates an independent SpiderMonkey
//! Compartment via `JS_NewGlobalObject`. The sandbox object's properties are
//! copied onto the new global so that `vm.runInNewContext(code, {x: 42})`
//! makes `x` available as a global variable in the sandbox realm.
//!
//! Code execution uses `AutoRealm` to temporarily switch the JSContext into
//! the sandbox Compartment; dropping the `AutoRealm` restores the caller's
//! realm. Cross-Compartment object references are automatically wrapped by
//! SM's CCW (Cross-Compartment Wrapper) mechanism.
//!
//! ## Key APIs
//!
//! - `vm.createContext(sandbox?, opts?)` → creates new SM Realm, copies
//!   sandbox properties to the new global, returns the contextified sandbox
//! - `vm.runInNewContext(code, sandbox?, opts?)` → createContext + evaluate
//!   in the new Realm, returns the last expression value
//! - `vm.runInThisContext(code, opts?)` → evaluate in caller's Realm
//! - `vm.isContext(obj)` → checks if obj was contextified by createContext
//! - `vm.Script(code, opts?)` → pre-compiled script with runInContext /
//!   runInNewContext methods
//! - `vm.compileFunction(code, params?, opts?)` → compile a function body

use ::std::cell::RefCell;
use ::std::ptr::{self, NonNull};

use mozjs::conversions::unsafe_jsstr_to_string;
use mozjs::jsapi::*;
use mozjs::jsval::{BooleanValue, Int32Value, JSVal, NullValue, ObjectValue, UndefinedValue};
use mozjs::realm::AutoRealm;
use mozjs::rooted;
use mozjs::rust::wrappers2 as w2;
use mozjs::rust::wrappers2::JS_NewGlobalObject;
use mozjs::rust::{CompileOptionsWrapper, IdVector, RealmOptions, SIMPLE_GLOBAL_CLASS};

use crate::require::cache_builtin;

// ──────────────────────────────────────────────────────────────────────────
// VM Context Registry (thread-local)
// ──────────────────────────────────────────────────────────────────────────

// Tracks contextified objects on this thread so `vm.isContext()` can
// recognise them. Each entry maps a JSObject* to its sandbox global, the
// active code-generation policy (REQ-ENG-011 criterion 8), and the baseline
// set of the realm global's own keys at creation time (standard classes +
// realm intrinsics — captured BEFORE sandbox seeding so that seeded and
// code-created keys both propagate back on write-through).
thread_local! {
    static VM_CONTEXT_MAP: RefCell<Vec<(*mut JSObject, *mut JSObject, CodeGenerationFlags, ::std::rc::Rc<Vec<String>>)>> = RefCell::new(Vec::new());
}

/// Register a sandbox object as contextified, with its associated global,
/// code-generation policy, and global-key baseline.
fn register_context(
    sandbox: *mut JSObject,
    global: *mut JSObject,
    flags: CodeGenerationFlags,
    baseline: ::std::rc::Rc<Vec<String>>,
) {
    VM_CONTEXT_MAP.with(|m| {
        m.borrow_mut().push((sandbox, global, flags, baseline));
    });
}

/// Check whether an object has been contextified.
fn is_context_registered(obj: *mut JSObject) -> bool {
    VM_CONTEXT_MAP.with(|m| m.borrow().iter().any(|&(s, ..)| ptr::eq(s, obj)))
}

/// Look up the sandbox global for a contextified object.
fn get_context_global(obj: *mut JSObject) -> Option<*mut JSObject> {
    VM_CONTEXT_MAP.with(|m| {
        m.borrow()
            .iter()
            .find(|&&(s, ..)| ptr::eq(s, obj))
            .map(|&(_, g, ..)| g)
    })
}

/// Look up the global-key baseline for a contextified object.
fn get_context_baseline(obj: *mut JSObject) -> Option<::std::rc::Rc<Vec<String>>> {
    VM_CONTEXT_MAP.with(|m| {
        m.borrow()
            .iter()
            .find(|&&(s, ..)| ptr::eq(s, obj))
            .map(|&(_, _, _, ref b)| b.clone())
    })
}

// ──────────────────────────────────────────────────────────────────────────
// Code-generation policy (REQ-ENG-011 criterion 8: codeGeneration option)
// ──────────────────────────────────────────────────────────────────────────

/// Flags extracted from the `codeGeneration` option object.
///
/// Mirrors Node.js `vm` semantics: `codeGeneration: { strings: false, wasm: false }`
/// disables `eval`/`Function`/`new Function` string compilation and WebAssembly
/// module compilation inside the sandbox realm respectively. Both default to
/// `true` (allowed) when the option is absent or true.
#[derive(Clone, Copy, Default)]
struct CodeGenerationFlags {
    /// When `false`, `eval(...)` / `new Function(...)` / `Function(...)` throw.
    strings_allowed: bool,
    /// When `false`, `new WebAssembly.Module(...)` / `WebAssembly.compile(...)`
    /// are blocked by removing the WebAssembly global.
    wasm_allowed: bool,
}

impl CodeGenerationFlags {
    /// Default-permissive flags (everything allowed).
    #[inline]
    fn permissive() -> Self {
        CodeGenerationFlags {
            strings_allowed: true,
            wasm_allowed: true,
        }
    }

    /// Returns `true` when no restrictions need to be applied.
    #[inline]
    fn is_unrestricted(self) -> bool {
        self.strings_allowed && self.wasm_allowed
    }
}

/// Parse the `codeGeneration` field from a JS options object.
///
/// Reads `opts.codeGeneration.strings` and `opts.codeGeneration.wasm`
/// as booleans (defaulting to `true` when absent). Returns the permissive
/// default when `opts` is not an object or lacks the `codeGeneration` field.
unsafe fn parse_code_generation_options(
    cx: *mut JSContext,
    opts_val: JSVal,
) -> CodeGenerationFlags {
    if !opts_val.is_object() {
        return CodeGenerationFlags::permissive();
    }

    let wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let raw_cx = cx;

    rooted!(&in(wrapped_cx) let opts = opts_val.to_object());

    // Read opts.codeGeneration
    let mut cgen_val = UndefinedValue();
    let got = JS_GetProperty(
        raw_cx,
        opts.handle().into(),
        c"codeGeneration".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut cgen_val,
        },
    );
    if !got || !cgen_val.is_object() {
        return CodeGenerationFlags::permissive();
    }

    rooted!(&in(wrapped_cx) let cgen = cgen_val.to_object());

    let read_bool = |key: &::std::ffi::CStr| -> bool {
        let mut v = UndefinedValue();
        let ok = JS_GetProperty(
            raw_cx,
            cgen.handle().into(),
            key.as_ptr(),
            MutableHandle::<JSVal> {
                _phantom_0: ::std::marker::PhantomData,
                ptr: &mut v,
            },
        );
        if !ok || !v.is_boolean() {
            true // absent / non-bool → default allowed
        } else {
            v.to_boolean()
        }
    };

    CodeGenerationFlags {
        strings_allowed: read_bool(c"strings"),
        wasm_allowed: read_bool(c"wasm"),
    }
}

/// Native callback for the disabled `eval` / `Function` stub.
///
/// Throws a `EvalError` mirroring Node's "Code generation from strings
/// disallowed for this context" message so callers can detect the policy.
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_strings_disabled(cx: *mut JSContext, _argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, _argc);
    JS_ReportErrorUTF8(
        cx,
        c"Code generation from strings disallowed for this context".as_ptr(),
    );
    args.rval().set(UndefinedValue());
    false
}

/// Apply code-generation restrictions to the sandbox global.
///
/// MUST run inside the sandbox AutoRealm. When `strings_allowed` is `false`,
/// overwrites the global `eval` and `Function` with a throwing stub. When
/// `wasm_allowed` is `false`, deletes the `WebAssembly` global if present.
/// SpiderMonkey lazily resolves standard classes via `JS_ResolveStandardClass`,
/// so we redefine the properties as configurable:false enumerable:false
/// functions which take precedence over the resolved standard class.
fn apply_code_generation_restrictions(
    realm_cx: &mut mozjs::context::JSContext,
    global: *mut JSObject,
    flags: CodeGenerationFlags,
) {
    if global.is_null() || flags.is_unrestricted() {
        return;
    }

    let raw_cx = unsafe { realm_cx.raw_cx() };
    rooted!(&in(realm_cx) let global_root = global);

    if !flags.strings_allowed {
        // Replace `eval` with a throwing function.
        unsafe {
            let eval_fn = JS_NewFunction(raw_cx, Some(vm_strings_disabled), 1, 0, c"eval".as_ptr());
            if !eval_fn.is_null() {
                let eval_obj = JS_GetFunctionObject(eval_fn);
                rooted!(&in(realm_cx) let ev = mozjs::jsval::ObjectValue(eval_obj));
                JS_DefineProperty(
                    raw_cx,
                    global_root.handle().into(),
                    c"eval".as_ptr(),
                    ev.handle().into(),
                    0u32,
                );
            }

            // Replace `Function` constructor (also blocks `new Function(...)`).
            let func_fn = JS_NewFunction(
                raw_cx,
                Some(vm_strings_disabled),
                1,
                0,
                c"Function".as_ptr(),
            );
            if !func_fn.is_null() {
                let func_obj = JS_GetFunctionObject(func_fn);
                rooted!(&in(realm_cx) let fv = mozjs::jsval::ObjectValue(func_obj));
                JS_DefineProperty(
                    raw_cx,
                    global_root.handle().into(),
                    c"Function".as_ptr(),
                    fv.handle().into(),
                    0u32,
                );
            }
        }
    }

    if !flags.wasm_allowed {
        // Delete `WebAssembly` global if present (lazily-resolved or defined).
        unsafe {
            JS_DeleteProperty1(raw_cx, global_root.handle().into(), c"WebAssembly".as_ptr());
        }
    }
}

// ──────────────────────────────────────────────────────────────────────────
// Module install
// ──────────────────────────────────────────────────────────────────────────

pub fn install(cx: &mut mozjs::context::JSContext) {
    rooted!(&in(cx) let vm_obj = unsafe { w2::JS_NewPlainObject(cx) });
    if vm_obj.get().is_null() {
        return;
    }

    unsafe {
        w2::JS_DefineFunction(
            cx,
            vm_obj.handle(),
            c"runInThisContext".as_ptr(),
            Some(vm_run_in_this_context),
            2,
            0,
        );
        w2::JS_DefineFunction(
            cx,
            vm_obj.handle(),
            c"runInNewContext".as_ptr(),
            Some(vm_run_in_new_context),
            3,
            0,
        );
        w2::JS_DefineFunction(
            cx,
            vm_obj.handle(),
            c"runInContext".as_ptr(),
            Some(vm_run_in_context),
            3,
            0,
        );
        w2::JS_DefineFunction(
            cx,
            vm_obj.handle(),
            c"createContext".as_ptr(),
            Some(vm_create_context),
            2,
            0,
        );
        w2::JS_DefineFunction(
            cx,
            vm_obj.handle(),
            c"isContext".as_ptr(),
            Some(vm_is_context),
            1,
            0,
        );
        w2::JS_DefineFunction(
            cx,
            vm_obj.handle(),
            c"compileFunction".as_ptr(),
            Some(vm_compile_function),
            2,
            0,
        );

        // Script constructor
        let script_fn = JS_NewFunction(
            cx.raw_cx(),
            Some(vm_script_ctor),
            2,
            JSFUN_CONSTRUCTOR,
            c"Script".as_ptr(),
        );
        if !script_fn.is_null() {
            let script_obj = JS_GetFunctionObject(script_fn);

            // Create Script.prototype with runIn* methods
            rooted!(&in(cx) let proto = w2::JS_NewPlainObject(cx));
            if !proto.get().is_null() {
                w2::JS_DefineFunction(
                    cx,
                    proto.handle(),
                    c"runInThisContext".as_ptr(),
                    Some(vm_script_run_in_this_context),
                    1,
                    0,
                );
                w2::JS_DefineFunction(
                    cx,
                    proto.handle(),
                    c"runInContext".as_ptr(),
                    Some(vm_script_run_in_context),
                    2,
                    0,
                );
                w2::JS_DefineFunction(
                    cx,
                    proto.handle(),
                    c"runInNewContext".as_ptr(),
                    Some(vm_script_run_in_new_context),
                    2,
                    0,
                );

                // Set Script.prototype = proto on the constructor function
                let proto_val = ObjectValue(proto.get());
                rooted!(&in(cx) let pv = proto_val);
                rooted!(&in(cx) let script_h = script_obj);
                JS_DefineProperty(
                    cx.raw_cx(),
                    script_h.handle().into(),
                    c"prototype".as_ptr(),
                    pv.handle().into(),
                    JSPROP_ENUMERATE as u32,
                );
            }

            // Define vm.Script = constructor function
            let script_val = ObjectValue(script_obj);
            rooted!(&in(cx) let sv = script_val);
            JS_DefineProperty(
                cx.raw_cx(),
                vm_obj.handle().into(),
                c"Script".as_ptr(),
                sv.handle().into(),
                JSPROP_ENUMERATE as u32,
            );
        }
    }

    cache_builtin(cx, "vm", vm_obj.get());
}

// ──────────────────────────────────────────────────────────────────────────
// vm.createContext — create an independent SM Realm
// ──────────────────────────────────────────────────────────────────────────

/// Creates a new SpiderMonkey Compartment with `JS_NewGlobalObject`,
/// copies sandbox properties onto the new global, marks the sandbox
/// as contextified, and returns it.
///
/// If the sandbox is already contextified, returns it as-is.
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_create_context(cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);

    // Get or create the sandbox object.
    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;

    let sandbox = if argc > 0 && (*args.get(0).ptr).is_object() {
        rooted!(&in(cx_ref) let sb = (*args.get(0).ptr).to_object());
        sb.get()
    } else {
        // No sandbox provided — create an empty object.
        rooted!(&in(cx_ref) let empty = w2::JS_NewPlainObject(cx_ref));
        empty.get()
    };

    if sandbox.is_null() {
        args.rval().set(UndefinedValue());
        return true;
    }

    // If already contextified, return as-is.
    if is_context_registered(sandbox) {
        args.rval().set(ObjectValue(sandbox));
        return true;
    }

    // Create a new independent SM Realm/Compartment.
    let options = RealmOptions::default();

    rooted!(&in(cx_ref) let sandbox_global = JS_NewGlobalObject(
        cx_ref,
        &SIMPLE_GLOBAL_CLASS,
        ptr::null_mut(),
        OnNewGlobalHookOption::FireOnNewGlobalHook,
        &*options,
    ));

    if sandbox_global.get().is_null() {
        args.rval().set(UndefinedValue());
        return true;
    }

    // Parse the codeGeneration option (arg 1) BEFORE entering the AutoRealm.
    // REQ-ENG-011 criterion 8: codeGeneration can disable eval/function.
    let cgen_opts_val = if argc > 1 {
        *args.get(1).ptr
    } else {
        UndefinedValue()
    };
    let cgen_flags = unsafe { parse_code_generation_options(cx, cgen_opts_val) };

    // Phase 1: Collect sandbox properties in the CALLER's Realm (before
    // entering AutoRealm). This is critical because the sandbox object lives
    // in the caller's compartment; iterating it from the sandbox realm would
    // see it through a CCW, which may not enumerate properties correctly.
    let sandbox_props = collect_sandbox_properties(cx_ref, sandbox);

    // Phase 2: Enter the new Realm and define collected properties on the
    // sandbox global. Values from the caller's realm are automatically wrapped
    // as CCWs by SpiderMonkey when defined in the sandbox realm.
    {
        let mut realm = AutoRealm::new_from_handle(cx_ref, sandbox_global.handle());
        let realm_cx: &mut mozjs::context::JSContext = &mut realm;

        // Baseline the global's own keys BEFORE seeding sandbox properties.
        // The enumeration itself force-resolves every standard class (see
        // capture_global_baseline), so later lazy resolutions cannot leak
        // into the write-back set.
        let baseline = capture_global_baseline(realm_cx, sandbox_global.get());

        define_properties_on_global(realm_cx, sandbox_global.get(), &sandbox_props);

        // Apply code-generation restrictions (eval/Function/WebAssembly).
        apply_code_generation_restrictions(realm_cx, sandbox_global.get(), cgen_flags);

        // Register as contextified (baseline captured pre-seed).
        register_context(
            sandbox,
            sandbox_global.get(),
            cgen_flags,
            ::std::rc::Rc::new(baseline),
        );
    }

    // Mark with __isVMContext for isContext() backwards compat.
    rooted!(&in(cx_ref) let sandbox_root = sandbox);
    rooted!(&in(cx_ref) let marker = BooleanValue(true));
    JS_DefineProperty(
        cx,
        sandbox_root.handle().into(),
        c"__isVMContext".as_ptr(),
        marker.handle().into(),
        0,
    );

    args.rval().set(ObjectValue(sandbox_root.get()));
    true
}

/// Phase 1: Collect sandbox properties in the CALLER's Realm.
///
/// Iterates the sandbox object's own enumerable string-keyed properties
/// using `GetPropertyKeys` + `JS_GetPropertyById`, and stores each key as
/// a Rust `String` and each value as a GC-traced `Heap<JS::Value>`.
///
/// This MUST run before entering the sandbox AutoRealm, because the sandbox
/// object lives in the caller's compartment. From the sandbox realm it would
/// be a CCW, and `Object.keys()` / `GetPropertyKeys` on a CCW may not
/// enumerate properties correctly.
fn collect_sandbox_properties(
    cx: &mut mozjs::context::JSContext,
    sandbox: *mut JSObject,
) -> Vec<(::std::string::String, Box<Heap<JS::Value>>)> {
    let mut props = Vec::new();
    if sandbox.is_null() {
        return props;
    }

    let raw_cx = unsafe { cx.raw_cx() };
    rooted!(&in(cx) let sandbox_root = sandbox);
    let mut ids = unsafe { IdVector::new(raw_cx) };
    let ok = unsafe {
        GetPropertyKeys(
            raw_cx,
            sandbox_root.handle().into(),
            JSITER_OWNONLY,
            ids.handle_mut(),
        )
    };
    if !ok {
        return props;
    }

    for jsid in &*ids {
        // Only process string-keyed properties (skip symbols and int keys).
        if !jsid.is_string() {
            continue;
        }
        let key_str_ptr = jsid.to_string();
        if key_str_ptr.is_null() {
            continue;
        }
        let key = unsafe { unsafe_jsstr_to_string(raw_cx, NonNull::new_unchecked(key_str_ptr)) };

        // Get the property value by id using the raw JS_GetPropertyById
        // (takes *mut JSContext + raw Handle types from mozjs_sys).
        let id_h = Handle::<jsid> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: jsid as *const jsid as *mut jsid,
        };
        let mut val = UndefinedValue();
        let val_h = MutableHandle::<JS::Value> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut val,
        };
        let got = unsafe { JS_GetPropertyById(raw_cx, sandbox_root.handle().into(), id_h, val_h) };
        if !got {
            continue;
        }

        // Store key as Rust String, value as Box<Heap<Value>> (GC-traced,
        // survives across realm switches).
        let heap_val = Heap::boxed(val);
        props.push((key, heap_val));
    }

    props
}

/// Phase 2: Define collected properties on the sandbox Realm's global.
///
/// Runs INSIDE the sandbox AutoRealm. For each (key, value) pair collected
/// in Phase 1, defines the property on the global object. Values from the
/// caller's realm are automatically wrapped as CCWs by SpiderMonkey.
fn define_properties_on_global(
    realm_cx: &mut mozjs::context::JSContext,
    global: *mut JSObject,
    props: &[(::std::string::String, Box<Heap<JS::Value>>)],
) {
    if global.is_null() {
        return;
    }

    let raw_cx = unsafe { realm_cx.raw_cx() };
    rooted!(&in(realm_cx) let global_root = global);

    for (key, heap_val) in props {
        let c_key = bun_core::ZBox::from_bytes(key.as_bytes());
        if c_key.as_ptr().is_null() {
            continue;
        }

        // SpiderMonkey automatically wraps cross-compartment values as CCWs
        // when defining the property. Heap::handle() returns a Handle<Value>
        // from mozjs_sys which is compatible with the raw JS_DefineProperty.
        let val_h = unsafe { heap_val.handle() };
        unsafe {
            JS_DefineProperty(
                raw_cx,
                global_root.handle().into(),
                c_key.as_ptr(),
                val_h,
                JSPROP_ENUMERATE as u32,
            );
        }
    }
}

/// Capture the realm global's own string keys. MUST run inside the sandbox
/// AutoRealm. SIMPLE_GLOBAL_CLASS's enumerate hook is
/// JS_EnumerateStandardClasses, so the first enumeration force-resolves every
/// standard class — after this call the key set is deterministic (standard
/// classes + realm intrinsics), which is exactly what the write-back filter
/// needs to skip.
///
/// Captured BEFORE sandbox seeding: seeded keys must NOT be in the baseline so
/// later in-sandbox mutations of them propagate back to the sandbox object.
unsafe fn capture_global_baseline(
    realm_cx: &mut mozjs::context::JSContext,
    global: *mut JSObject,
) -> Vec<String> {
    let mut keys = Vec::new();
    if global.is_null() {
        return keys;
    }
    let raw_cx = unsafe { realm_cx.raw_cx() };
    rooted!(&in(realm_cx) let global_root = global);
    let mut ids = unsafe { IdVector::new(raw_cx) };
    let ok = unsafe {
        GetPropertyKeys(
            raw_cx,
            global_root.handle().into(),
            JSITER_OWNONLY,
            ids.handle_mut(),
        )
    };
    if !ok {
        return keys;
    }
    for jsid in &*ids {
        if !jsid.is_string() {
            continue;
        }
        let key_str_ptr = jsid.to_string();
        if key_str_ptr.is_null() {
            continue;
        }
        let key = unsafe {
            unsafe_jsstr_to_string(raw_cx, NonNull::new_unchecked(key_str_ptr))
        };
        keys.push(key);
    }
    keys
}

/// Copy the sandbox object's own enumerable string-keyed properties onto the
/// realm global (sandbox → global). Runs before each evaluation so properties
/// added to the sandbox object after createContext are visible inside the
/// realm (Node semantics: the contextified object is the realm's global view).
unsafe fn sync_sandbox_into_global(
    cx: &mut mozjs::context::JSContext,
    sandbox: *mut JSObject,
    global: *mut JSObject,
) {
    if sandbox.is_null() || global.is_null() {
        return;
    }
    // Phase 1: collect in the CALLER's realm (sandbox lives there).
    let props = collect_sandbox_properties(cx, sandbox);
    // Phase 2: define inside the sandbox realm.
    {
        rooted!(&in(cx) let global_h = global);
        let mut realm = AutoRealm::new_from_handle(cx, global_h.handle());
        let realm_cx: &mut mozjs::context::JSContext = &mut realm;
        define_properties_on_global(realm_cx, global, &props);
    }
}

/// Write global → sandbox: after evaluating code in the realm, copy every own
/// string-keyed global property that is NOT in the creation-time baseline back
/// onto the sandbox object. This is the write-through half of the vm contract:
/// `script.runInContext(ctx)` leaves `sandbox.x === <value assigned in vm>`.
/// Values belonging to the realm are wrapped as CCWs automatically.
///
/// MUST be called with no exception pending (after a successful evaluation).
unsafe fn copy_global_writes_to_sandbox(
    cx: &mut mozjs::context::JSContext,
    global: *mut JSObject,
    sandbox: *mut JSObject,
    baseline: &[String],
) {
    if global.is_null() || sandbox.is_null() {
        return;
    }
    rooted!(&in(cx) let global_h = global);
    let mut realm = AutoRealm::new_from_handle(cx, global_h.handle());
    let realm_cx: &mut mozjs::context::JSContext = &mut realm;
    let raw_cx = unsafe { realm_cx.raw_cx() };

    rooted!(&in(realm_cx) let global_root = global);
    rooted!(&in(realm_cx) let sandbox_root = sandbox);

    let mut ids = unsafe { IdVector::new(raw_cx) };
    let ok = unsafe {
        GetPropertyKeys(
            raw_cx,
            global_root.handle().into(),
            JSITER_OWNONLY,
            ids.handle_mut(),
        )
    };
    if !ok {
        return;
    }
    for jsid in &*ids {
        if !jsid.is_string() {
            continue;
        }
        let key_str_ptr = jsid.to_string();
        if key_str_ptr.is_null() {
            continue;
        }
        let key =
            unsafe { unsafe_jsstr_to_string(raw_cx, NonNull::new_unchecked(key_str_ptr)) };
        if baseline.iter().any(|b| b == &key) {
            continue;
        }
        let id_h = Handle::<jsid> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: jsid as *const jsid as *mut jsid,
        };
        let mut val = UndefinedValue();
        let val_h = MutableHandle::<JS::Value> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut val,
        };
        if !unsafe { JS_GetPropertyById(raw_cx, global_root.handle().into(), id_h, val_h) } {
            continue;
        }
        // Set through the cross-compartment wrapper onto the caller-realm
        // sandbox object; SM wraps realm-owned values automatically.
        rooted!(&in(realm_cx) let val_root = val);
        unsafe {
            JS_SetPropertyById(
                raw_cx,
                sandbox_root.handle().into(),
                id_h,
                val_root.handle().into(),
            );
        }
    }
}

// ──────────────────────────────────────────────────────────────────────────
// vm.runInNewContext — createContext + evaluate in sandbox Realm
// ──────────────────────────────────────────────────────────────────────────

/// Creates a new context (if needed), enters the sandbox Realm, evaluates
/// the code, and returns the last expression value.
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_run_in_new_context(cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);
    if argc == 0 || !(*args.get(0).ptr).is_string() {
        JS_ReportErrorUTF8(cx, c"runInNewContext requires a code string".as_ptr());
        return false;
    }

    let code = crate::js_to_rust_string(cx, *args.get(0).ptr);

    // Get sandbox (arg 1) — if not provided, create a default empty one.
    let sandbox_val = if argc > 1 {
        *args.get(1).ptr
    } else {
        UndefinedValue()
    };
    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;
    let sandbox = if sandbox_val.is_object() {
        rooted!(&in(cx_ref) let sb = sandbox_val.to_object());
        sb.get()
    } else {
        rooted!(&in(cx_ref) let empty = w2::JS_NewPlainObject(cx_ref));
        empty.get()
    };

    // Create or reuse context.
    let sandbox_global = if is_context_registered(sandbox) {
        get_context_global(sandbox).unwrap_or(ptr::null_mut())
    } else {
        // Call vm_create_context internally to create the Realm.
        // Forward arg 0 (sandbox) AND arg 2 (options, carries codeGeneration)
        // so vm_create_context parses the codeGeneration policy (criterion 8).
        // vp layout for CallArgs::from_vp: [rval_slot, magic_marker, arg0, ...]
        let opts_val = if argc > 2 {
            *args.get(2).ptr
        } else {
            UndefinedValue()
        };
        let mut ctx_vp = [
            UndefinedValue(),
            UndefinedValue(),
            ObjectValue(sandbox),
            opts_val,
        ];
        if !vm_create_context(cx, 2, ctx_vp.as_mut_ptr()) {
            args.rval().set(UndefinedValue());
            return false;
        }
        // After createContext, sandbox is registered.
        get_context_global(sandbox).unwrap_or(ptr::null_mut())
    };

    if sandbox_global.is_null() {
        JS_ReportErrorUTF8(
            cx,
            c"runInNewContext: failed to create sandbox context".as_ptr(),
        );
        return false;
    }

    // Get filename from options (arg 2).
    let filename = if argc > 2 && (*args.get(2).ptr).is_object() {
        rooted!(&in(cx_ref) let opts = (*args.get(2).ptr).to_object());
        let mut fn_val = UndefinedValue();
        JS_GetProperty(
            cx,
            opts.handle().into(),
            c"filename".as_ptr(),
            MutableHandle::<JSVal> {
                _phantom_0: ::std::marker::PhantomData,
                ptr: &mut fn_val,
            },
        );
        if fn_val.is_string() {
            crate::js_to_rust_string(cx, fn_val)
        } else {
            "vm.js".to_string()
        }
    } else if argc > 2 && (*args.get(2).ptr).is_string() {
        crate::js_to_rust_string(cx, *args.get(2).ptr)
    } else {
        "vm.js".to_string()
    };

    // Write-through (sandbox → global): pick up properties added to the
    // sandbox object since createContext before evaluating.
    sync_sandbox_into_global(cx_ref, sandbox, sandbox_global);

    // Enter the sandbox Realm, evaluate code, return result.
    rooted!(&in(cx_ref) let global_h = sandbox_global);
    rooted!(&in(cx_ref) let mut rval = UndefinedValue());

    {
        let mut realm = AutoRealm::new_from_handle(cx_ref, global_h.handle());
        let realm_cx: &mut mozjs::context::JSContext = &mut realm;

        // Evaluate in the sandbox Realm.
        let c_filename = ::std::ffi::CString::new(filename.clone())
            .unwrap_or_else(|_| ::std::ffi::CString::new("vm.js").unwrap());
        let compile_opts = CompileOptionsWrapper::new(realm_cx, c_filename, 1);

        let result = mozjs::rust::evaluate_script(
            realm_cx,
            global_h.handle(),
            &code,
            rval.handle_mut(),
            compile_opts,
        );

        if result.is_err() {
            return false;
        }

        // Run pending jobs (microtasks, etc.).
        unsafe {
            mozjs::jsapi::js::RunJobs(realm_cx.raw_cx());
        }
    }

    // Write-through (global → sandbox): vm writes land on the sandbox object.
    if let Some(baseline) = get_context_baseline(sandbox) {
        copy_global_writes_to_sandbox(cx_ref, sandbox_global, sandbox, &baseline);
    }

    args.rval().set(rval.get());
    true
}

// ──────────────────────────────────────────────────────────────────────────
// vm.runInContext — evaluate in an existing contextified sandbox Realm
// ──────────────────────────────────────────────────────────────────────────

/// `vm.runInContext(code, contextifiedSandbox[, options])` — evaluates `code`
/// in the Realm of an already-contextified sandbox. Mirrors
/// `Script.runInContext` (including the write-through contract): sandbox
/// properties added after createContext are visible inside the realm, and
/// global writes inside the code land back on the sandbox object.
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_run_in_context(cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);
    if argc == 0 || !(*args.get(0).ptr).is_string() {
        JS_ReportErrorUTF8(cx, c"runInContext requires a code string".as_ptr());
        return false;
    }
    if argc < 2 || !(*args.get(1).ptr).is_object() {
        JS_ReportErrorUTF8(
            cx,
            c"runInContext requires a contextified sandbox argument".as_ptr(),
        );
        return false;
    }
    let code = crate::js_to_rust_string(cx, *args.get(0).ptr);

    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;
    rooted!(&in(cx_ref) let sandbox = (*args.get(1).ptr).to_object());

    let sandbox_global = match get_context_global(sandbox.get()) {
        Some(g) if !g.is_null() => g,
        _ => {
            JS_ReportErrorUTF8(
                cx,
                c"runInContext: sandbox is not a contextified object".as_ptr(),
            );
            return false;
        }
    };

    // options (arg 2): filename override.
    let filename = if argc > 2 && (*args.get(2).ptr).is_object() {
        rooted!(&in(cx_ref) let opts = (*args.get(2).ptr).to_object());
        let mut fn_val = UndefinedValue();
        JS_GetProperty(
            cx,
            opts.handle().into(),
            c"filename".as_ptr(),
            MutableHandle::<JSVal> {
                _phantom_0: ::std::marker::PhantomData,
                ptr: &mut fn_val,
            },
        );
        if fn_val.is_string() {
            crate::js_to_rust_string(cx, fn_val)
        } else {
            "vm.js".to_string()
        }
    } else {
        "vm.js".to_string()
    };

    // Write-through (sandbox → global) before evaluating.
    sync_sandbox_into_global(cx_ref, sandbox.get(), sandbox_global);

    rooted!(&in(cx_ref) let global_h = sandbox_global);
    rooted!(&in(cx_ref) let mut rval = UndefinedValue());

    {
        let mut realm = AutoRealm::new_from_handle(cx_ref, global_h.handle());
        let realm_cx: &mut mozjs::context::JSContext = &mut realm;

        let c_filename = ::std::ffi::CString::new(filename.clone())
            .unwrap_or_else(|_| ::std::ffi::CString::new("vm.js").unwrap());
        let compile_opts = CompileOptionsWrapper::new(realm_cx, c_filename, 1);

        let result = mozjs::rust::evaluate_script(
            realm_cx,
            global_h.handle(),
            &code,
            rval.handle_mut(),
            compile_opts,
        );

        if result.is_err() {
            return false;
        }

        unsafe {
            mozjs::jsapi::js::RunJobs(realm_cx.raw_cx());
        }
    }

    // Write-through (global → sandbox).
    if let Some(baseline) = get_context_baseline(sandbox.get()) {
        copy_global_writes_to_sandbox(cx_ref, sandbox_global, sandbox.get(), &baseline);
    }

    args.rval().set(rval.get());
    true
}

// ──────────────────────────────────────────────────────────────────────────
// vm.runInThisContext — evaluate in caller's Realm
// ──────────────────────────────────────────────────────────────────────────

#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_run_in_this_context(cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);
    if argc == 0 || !(*args.get(0).ptr).is_string() {
        JS_ReportErrorUTF8(cx, c"runInThisContext requires a code string".as_ptr());
        return false;
    }

    let code = crate::js_to_rust_string(cx, *args.get(0).ptr);
    let filename = if argc > 1 && (*args.get(1).ptr).is_object() {
        let mut wrapped_cx3 = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
        let cx_ref3 = &mut wrapped_cx3;
        rooted!(&in(cx_ref3) let opts = (*args.get(1).ptr).to_object());
        let mut fn_val = UndefinedValue();
        JS_GetProperty(
            cx,
            opts.handle().into(),
            c"filename".as_ptr(),
            MutableHandle::<JSVal> {
                _phantom_0: ::std::marker::PhantomData,
                ptr: &mut fn_val,
            },
        );
        if fn_val.is_string() {
            crate::js_to_rust_string(cx, fn_val)
        } else {
            "vm.js".to_string()
        }
    } else if argc > 1 && (*args.get(1).ptr).is_string() {
        crate::js_to_rust_string(cx, *args.get(1).ptr)
    } else {
        "vm.js".to_string()
    };

    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;
    let global = JS::CurrentGlobalOrNull(cx_ref.raw_cx());

    let c_filename = ::std::ffi::CString::new(filename.clone())
        .unwrap_or_else(|_| ::std::ffi::CString::new("vm.js").unwrap());
    let compile_opts = CompileOptionsWrapper::new(cx_ref, c_filename, 1);

    rooted!(&in(cx_ref) let global_h = global);
    rooted!(&in(cx_ref) let mut rval = UndefinedValue());

    let result = mozjs::rust::evaluate_script(
        cx_ref,
        global_h.handle(),
        &code,
        rval.handle_mut(),
        compile_opts,
    );

    if result.is_err() {
        return false;
    }

    args.rval().set(rval.get());
    true
}

// ──────────────────────────────────────────────────────────────────────────
// vm.isContext
// ──────────────────────────────────────────────────────────────────────────

#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_is_context(_cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);
    if argc > 0 && (*args.get(0).ptr).is_object() {
        let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(_cx));
        let cx_ref = &mut wrapped_cx;
        rooted!(&in(cx_ref) let obj = (*args.get(0).ptr).to_object());
        // Check our VM_CONTEXT_MAP registry (primary) AND the legacy
        // __isVMContext marker (secondary, for objects contextified before
        // this process started or from a different isolate).
        let registered = is_context_registered(obj.get());
        let marker = if !registered {
            let mut val = UndefinedValue();
            JS_GetProperty(
                _cx,
                obj.handle().into(),
                c"__isVMContext".as_ptr(),
                MutableHandle::<JSVal> {
                    _phantom_0: ::std::marker::PhantomData,
                    ptr: &mut val,
                },
            );
            val.is_boolean() && val.to_boolean()
        } else {
            true
        };
        args.rval().set(BooleanValue(marker));
    } else {
        args.rval().set(BooleanValue(false));
    }
    true
}

// ──────────────────────────────────────────────────────────────────────────
// vm.compileFunction
// ──────────────────────────────────────────────────────────────────────────

#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_compile_function(cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);
    if argc == 0 || !(*args.get(0).ptr).is_string() {
        JS_ReportErrorUTF8(cx, c"compileFunction requires a code string".as_ptr());
        return false;
    }

    let code = crate::js_to_rust_string(cx, *args.get(0).ptr);
    // Node semantics: `vm.compileFunction(code[, params[, options]])` — the
    // second argument is the array of parameter names
    // (`compileFunction('return a+b', ['a','b'])` → `function(a,b){...}`).
    // A plain string is accepted as a function name (bao extension).
    let mut params = Vec::new();
    let mut fn_name = "anonymous".to_string();
    if argc > 1 {
        let pval = *args.get(1).ptr;
        if pval.is_object() {
            let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
            let cx_ref = &mut wrapped_cx;
            rooted!(&in(cx_ref) let arr = pval.to_object());
            let mut len_val = UndefinedValue();
            JS_GetProperty(
                cx,
                arr.handle().into(),
                c"length".as_ptr(),
                MutableHandle::<JSVal> {
                    _phantom_0: ::std::marker::PhantomData,
                    ptr: &mut len_val,
                },
            );
            let len = if len_val.is_int32() {
                len_val.to_int32().max(0) as u32
            } else {
                0
            };
            for i in 0..len {
                let mut elem = UndefinedValue();
                JS_GetElement(
                    cx,
                    arr.handle().into(),
                    i,
                    MutableHandle::<JSVal> {
                        _phantom_0: ::std::marker::PhantomData,
                        ptr: &mut elem,
                    },
                );
                if elem.is_string() {
                    params.push(crate::js_to_rust_string(cx, elem));
                }
            }
        } else if pval.is_string() {
            fn_name = crate::js_to_rust_string(cx, pval);
        }
    }

    let wrapped = format!(
        "(function {}({}) {{ {} }})",
        fn_name,
        params.join(", "),
        code
    );

    let c_filename = bun_core::ZBox::from_bytes("vm.js".as_bytes());
    let opts = mozjs::glue::NewCompileOptions(cx, c_filename.as_ptr() as *const _, 1);
    if opts.is_null() {
        args.rval().set(UndefinedValue());
        return false;
    }

    let mut src = mozjs::rust::transform_str_to_source_text(&wrapped);
    let mut rval = UndefinedValue();
    let rval_h = MutableHandle::<JSVal> {
        _phantom_0: ::std::marker::PhantomData,
        ptr: &mut rval,
    };
    let ok = mozjs_sys::jsapi::JS::Evaluate2(cx, opts, &mut src, rval_h);
    libc::free(opts as *mut _);

    if ok && rval.is_object() {
        args.rval().set(rval);
        true
    } else {
        false
    }
}

// ──────────────────────────────────────────────────────────────────────────
// vm.Script constructor and methods
// ──────────────────────────────────────────────────────────────────────────

#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_script_ctor(cx: *mut JSContext, argc: u32, vp: *mut JSVal) -> bool {
    let args = CallArgs::from_vp(vp, argc);
    if argc == 0 || !(*args.get(0).ptr).is_string() {
        JS_ReportErrorUTF8(cx, c"Script requires a code string argument".as_ptr());
        return false;
    }

    let code = crate::js_to_rust_string(cx, *args.get(0).ptr);

    // Get filename from options
    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;

    let filename = if argc > 1 && (*args.get(1).ptr).is_object() {
        rooted!(&in(cx_ref) let opts = (*args.get(1).ptr).to_object());
        let mut fn_val = UndefinedValue();
        JS_GetProperty(
            cx,
            opts.handle().into(),
            c"filename".as_ptr(),
            MutableHandle::<JSVal> {
                _phantom_0: ::std::marker::PhantomData,
                ptr: &mut fn_val,
            },
        );
        if fn_val.is_string() {
            crate::js_to_rust_string(cx, fn_val)
        } else {
            "vm.js".to_string()
        }
    } else if argc > 1 && (*args.get(1).ptr).is_string() {
        crate::js_to_rust_string(cx, *args.get(1).ptr)
    } else {
        "vm.js".to_string()
    };

    // Use the `this` object that SM auto-creates for `new Script()` — it
    // already has Script.prototype as its prototype. If called without `new`,
    // create a plain object and set its prototype manually.
    let this_val = args.thisv();
    let this_obj = if this_val.is_object() {
        rooted!(&in(cx_ref) let this_root = this_val.to_object());
        if this_root.get().is_null() {
            rooted!(&in(cx_ref) let fallback = w2::JS_NewPlainObject(cx_ref));
            // Set prototype to Script.prototype
            rooted!(&in(cx_ref) let script_ctor_val = args.callee());
            let mut proto_val = UndefinedValue();
            JS_GetProperty(
                cx,
                script_ctor_val.handle().into(),
                c"prototype".as_ptr(),
                MutableHandle::<JSVal> {
                    _phantom_0: ::std::marker::PhantomData,
                    ptr: &mut proto_val,
                },
            );
            if proto_val.is_object() {
                rooted!(&in(cx_ref) let pv = proto_val.to_object());
                JS_SetPrototype(
                    cx_ref.raw_cx(),
                    fallback.handle().into(),
                    pv.handle().into(),
                );
            }
            fallback.get()
        } else {
            this_root.get()
        }
    } else {
        rooted!(&in(cx_ref) let fallback = w2::JS_NewPlainObject(cx_ref));
        // Set prototype to Script.prototype
        rooted!(&in(cx_ref) let script_ctor_val = args.callee());
        let mut proto_val = UndefinedValue();
        JS_GetProperty(
            cx,
            script_ctor_val.handle().into(),
            c"prototype".as_ptr(),
            MutableHandle::<JSVal> {
                _phantom_0: ::std::marker::PhantomData,
                ptr: &mut proto_val,
            },
        );
        if proto_val.is_object() {
            rooted!(&in(cx_ref) let pv = proto_val.to_object());
            JS_SetPrototype(
                cx_ref.raw_cx(),
                fallback.handle().into(),
                pv.handle().into(),
            );
        }
        fallback.get()
    };

    // Store code and filename as hidden properties
    let code_str = JS_NewStringCopyN(
        cx,
        code.as_ptr() as *const ::std::os::raw::c_char,
        code.len(),
    );
    if !code_str.is_null() {
        rooted!(&in(cx_ref) let cv = mozjs::jsval::StringValue(&*code_str));
        rooted!(&in(cx_ref) let this_root = this_obj);
        JS_DefineProperty(
            cx,
            this_root.handle().into(),
            c"__code".as_ptr(),
            cv.handle().into(),
            0,
        );
    }
    let fn_str = JS_NewStringCopyN(
        cx,
        filename.as_ptr() as *const ::std::os::raw::c_char,
        filename.len(),
    );
    if !fn_str.is_null() {
        rooted!(&in(cx_ref) let fv = mozjs::jsval::StringValue(&*fn_str));
        rooted!(&in(cx_ref) let this_root2 = this_obj);
        JS_DefineProperty(
            cx,
            this_root2.handle().into(),
            c"__filename".as_ptr(),
            fv.handle().into(),
            0,
        );
    }

    args.rval().set(ObjectValue(this_obj));
    true
}

/// Script.runInThisContext — evaluate in caller's Realm
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_script_run_in_this_context(
    cx: *mut JSContext,
    argc: u32,
    vp: *mut JSVal,
) -> bool {
    let args = CallArgs::from_vp(vp, argc);

    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;

    rooted!(&in(cx_ref) let this = args.thisv().to_object());

    let mut code_val = UndefinedValue();
    JS_GetProperty(
        cx,
        this.handle().into(),
        c"__code".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut code_val,
        },
    );
    let code = crate::js_to_rust_string(cx, code_val);

    let mut fn_val = UndefinedValue();
    JS_GetProperty(
        cx,
        this.handle().into(),
        c"__filename".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut fn_val,
        },
    );
    let filename = crate::js_to_rust_string(cx, fn_val);

    let global = JS::CurrentGlobalOrNull(cx_ref.raw_cx());

    let c_filename = ::std::ffi::CString::new(filename.clone())
        .unwrap_or_else(|_| ::std::ffi::CString::new("vm.js").unwrap());
    let compile_opts = CompileOptionsWrapper::new(cx_ref, c_filename, 1);

    rooted!(&in(cx_ref) let global_h = global);
    rooted!(&in(cx_ref) let mut rval = UndefinedValue());

    let result = mozjs::rust::evaluate_script(
        cx_ref,
        global_h.handle(),
        &code,
        rval.handle_mut(),
        compile_opts,
    );

    if result.is_err() {
        return false;
    }

    args.rval().set(rval.get());
    true
}

/// Script.runInContext(contextifiedSandbox) — evaluate in the sandbox Realm
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_script_run_in_context(
    cx: *mut JSContext,
    argc: u32,
    vp: *mut JSVal,
) -> bool {
    let args = CallArgs::from_vp(vp, argc);

    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;

    rooted!(&in(cx_ref) let this = args.thisv().to_object());

    // Read code and filename from Script instance
    let mut code_val = UndefinedValue();
    JS_GetProperty(
        cx,
        this.handle().into(),
        c"__code".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut code_val,
        },
    );
    let code = crate::js_to_rust_string(cx, code_val);

    let mut fn_val = UndefinedValue();
    JS_GetProperty(
        cx,
        this.handle().into(),
        c"__filename".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut fn_val,
        },
    );
    let filename = crate::js_to_rust_string(cx, fn_val);

    // Get contextified sandbox (arg 0)
    if argc == 0 || !(*args.get(0).ptr).is_object() {
        JS_ReportErrorUTF8(
            cx,
            c"runInContext requires a contextified sandbox argument".as_ptr(),
        );
        return false;
    }
    rooted!(&in(cx_ref) let sandbox = (*args.get(0).ptr).to_object());

    let sandbox_global = get_context_global(sandbox.get());
    if sandbox_global.is_none() {
        JS_ReportErrorUTF8(
            cx,
            c"runInContext: sandbox is not a contextified object".as_ptr(),
        );
        return false;
    }
    let global_ptr = sandbox_global.unwrap();
    if global_ptr.is_null() {
        JS_ReportErrorUTF8(cx, c"runInContext: sandbox global is null".as_ptr());
        return false;
    }

    // Enter sandbox Realm, evaluate code.
    // Write-through (sandbox → global) first: properties added to the sandbox
    // object since createContext must be visible inside the realm.
    sync_sandbox_into_global(cx_ref, sandbox.get(), global_ptr);

    rooted!(&in(cx_ref) let global_h = global_ptr);
    rooted!(&in(cx_ref) let mut rval = UndefinedValue());

    {
        let mut realm = AutoRealm::new_from_handle(cx_ref, global_h.handle());
        let realm_cx: &mut mozjs::context::JSContext = &mut realm;

        let c_filename = ::std::ffi::CString::new(filename.clone())
            .unwrap_or_else(|_| ::std::ffi::CString::new("vm.js").unwrap());
        let compile_opts = CompileOptionsWrapper::new(realm_cx, c_filename, 1);

        let result = mozjs::rust::evaluate_script(
            realm_cx,
            global_h.handle(),
            &code,
            rval.handle_mut(),
            compile_opts,
        );

        if result.is_err() {
            return false;
        }

        unsafe {
            mozjs::jsapi::js::RunJobs(realm_cx.raw_cx());
        }
    }

    // Write-through (global → sandbox): assignments inside the script land on
    // the contextified sandbox object (the vm contract this function owes).
    if let Some(baseline) = get_context_baseline(sandbox.get()) {
        copy_global_writes_to_sandbox(cx_ref, global_ptr, sandbox.get(), &baseline);
    }

    args.rval().set(rval.get());
    true
}

/// Script.runInNewContext(sandbox?) — createContext + evaluate
#[allow(unsafe_op_in_unsafe_fn)]
unsafe extern "C" fn vm_script_run_in_new_context(
    cx: *mut JSContext,
    argc: u32,
    vp: *mut JSVal,
) -> bool {
    let args = CallArgs::from_vp(vp, argc);

    let mut wrapped_cx = mozjs::context::JSContext::from_ptr(NonNull::new_unchecked(cx));
    let cx_ref = &mut wrapped_cx;

    rooted!(&in(cx_ref) let this = args.thisv().to_object());

    let mut code_val = UndefinedValue();
    JS_GetProperty(
        cx,
        this.handle().into(),
        c"__code".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut code_val,
        },
    );
    let code = crate::js_to_rust_string(cx, code_val);

    let mut fn_val = UndefinedValue();
    JS_GetProperty(
        cx,
        this.handle().into(),
        c"__filename".as_ptr(),
        MutableHandle::<JSVal> {
            _phantom_0: ::std::marker::PhantomData,
            ptr: &mut fn_val,
        },
    );
    let filename = crate::js_to_rust_string(cx, fn_val);

    // Get sandbox (arg 0) — if not provided, create a default empty one.
    let sandbox_val = if argc > 0 && (*args.get(0).ptr).is_object() {
        *args.get(0).ptr
    } else {
        UndefinedValue()
    };
    let sandbox = if sandbox_val.is_object() {
        rooted!(&in(cx_ref) let sb = sandbox_val.to_object());
        sb.get()
    } else {
        rooted!(&in(cx_ref) let empty = w2::JS_NewPlainObject(cx_ref));
        empty.get()
    };

    // Create or reuse context. Forward arg 1 (options, carries codeGeneration)
    // to vm_create_context so criterion 8 applies to script-created contexts.
    let sandbox_global = if is_context_registered(sandbox) {
        get_context_global(sandbox).unwrap_or(ptr::null_mut())
    } else {
        let opts_val = if argc > 1 {
            *args.get(1).ptr
        } else {
            UndefinedValue()
        };
        let mut ctx_vp = [
            UndefinedValue(),
            UndefinedValue(),
            ObjectValue(sandbox),
            opts_val,
        ];
        if !vm_create_context(cx, 2, ctx_vp.as_mut_ptr()) {
            args.rval().set(UndefinedValue());
            return false;
        }
        get_context_global(sandbox).unwrap_or(ptr::null_mut())
    };

    if sandbox_global.is_null() {
        JS_ReportErrorUTF8(
            cx,
            c"Script.runInNewContext: failed to create sandbox context".as_ptr(),
        );
        return false;
    }

    // Enter sandbox Realm, evaluate code.
    // Write-through (sandbox → global) first, then evaluate, then copy
    // vm writes back onto the sandbox object (same contract as
    // vm.runInNewContext / Script.runInContext).
    sync_sandbox_into_global(cx_ref, sandbox, sandbox_global);

    rooted!(&in(cx_ref) let global_h = sandbox_global);
    rooted!(&in(cx_ref) let mut rval = UndefinedValue());

    {
        let mut realm = AutoRealm::new_from_handle(cx_ref, global_h.handle());
        let realm_cx: &mut mozjs::context::JSContext = &mut realm;

        let c_filename = ::std::ffi::CString::new(filename.clone())
            .unwrap_or_else(|_| ::std::ffi::CString::new("vm.js").unwrap());
        let compile_opts = CompileOptionsWrapper::new(realm_cx, c_filename, 1);

        let result = mozjs::rust::evaluate_script(
            realm_cx,
            global_h.handle(),
            &code,
            rval.handle_mut(),
            compile_opts,
        );

        if result.is_err() {
            return false;
        }

        unsafe {
            mozjs::jsapi::js::RunJobs(realm_cx.raw_cx());
        }
    }

    if let Some(baseline) = get_context_baseline(sandbox) {
        copy_global_writes_to_sandbox(cx_ref, sandbox_global, sandbox, &baseline);
    }

    args.rval().set(rval.get());
    true
}