feat: Temporal.PlainTime until/since 差值计算

crates/oxide_builtins/src/temporal.rs

@@ -4592,6 +4592,50 @@ pub fn plain_time_compare<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
     NativeResult::Ok(JsValue::int(result))
 }
 
+// ───────────────────── PlainTime until / since ─────────────────────
+
+/// until/since 核心：receiver 与 other 归一为午夜后纳秒，经 `difference_core` 计算差值。
+///
+/// # 步骤
+/// 1. branding receiver 取槽 0 ns，other 经 `plain_time_like_ns` 归一。
+/// 2. `parse_difference_settings` 解析 options（default_largest=4=hour）。
+/// 3. 日期固定为 epoch（0,0,0），调 `difference_core` 输出 Duration。
+///
+/// # 边界与前提
+/// - since 复用 same 语义并整体取反（difference_core 内部处理），不调换两端。
+fn plain_time_difference<H: VmHost>(vm: &mut H, args: &[u8], since: bool) -> NativeResult {
+    let ptr = match receiver_obj(vm, args) {
+        Ok(p) => p,
+        Err(error) => return NativeResult::Err(error),
+    };
+    let obj = unsafe { &*ptr };
+    if let Err(error) = ensure_plain_time(vm, obj) {
+        return NativeResult::Err(error);
+    }
+    let receiver_ns = get_double_prop(obj, 0);
+    let other_val = if args.len() > 1 { vm.reg(args[1]) } else { JsValue::undefined() };
+    let other_ns = match plain_time_like_ns(vm, other_val) {
+        Ok(ns) => ns,
+        Err(error) => return NativeResult::Err(error),
+    };
+    let options_value = if args.len() > 2 { vm.reg(args[2]) } else { JsValue::undefined() };
+    let settings = match parse_difference_settings(vm, options_value, false, 4) {
+        Ok(settings) => settings,
+        Err(error) => return NativeResult::Err(error),
+    };
+    difference_core(vm, (0, 0, 0), receiver_ns as i128, (0, 0, 0), other_ns as i128, settings, since)
+}
+
+/// `Temporal.PlainTime.prototype.until(other, options)`。
+pub fn plain_time_until<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
+    plain_time_difference(vm, args, false)
+}
+
+/// `Temporal.PlainTime.prototype.since(other, options)`。
+pub fn plain_time_since<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
+    plain_time_difference(vm, args, true)
+}
+
 // ───────────────────── PlainDateTime 基础方法 ─────────────────────
 
 /// `Temporal.PlainDateTime` 构造器：保存 ISO 日期与午夜后纳秒。

crates/oxide_vm/src/bindings/bind_temporal.rs

@@ -692,6 +692,8 @@ pub fn bind_temporal(core: &Arc<KernelCore>, session: &KernelSession, global: &m
             ),
             ("valueOf", oxide_builtins::temporal::plain_time_value_of::<crate::vm::Vm> as *const (), 0),
             ("equals", oxide_builtins::temporal::plain_time_equals::<crate::vm::Vm> as *const (), 1),
+            ("until", oxide_builtins::temporal::plain_time_until::<crate::vm::Vm> as *const (), 1),
+            ("since", oxide_builtins::temporal::plain_time_since::<crate::vm::Vm> as *const (), 1),
         ],
     );
     bind_well_known_data_property(

crates/oxide_vm/tests/builtins_temporal_tests.rs

@@ -668,6 +668,44 @@ fn plain_time_compare_epoch_order() {
     assert_eq!(num(&mut vm, "Temporal.PlainTime.compare('23:59', '00:00')"), 1.0);
 }
 
+#[test]
+fn plain_time_until_since_normal() {
+    let mut vm = Vm::new();
+    let r = eval(&mut vm, "new Temporal.PlainTime(12, 30).until(new Temporal.PlainTime(13, 30)).toString()").unwrap();
+    assert_eq!(str_val(&vm, r), "PT1H");
+    let r = eval(&mut vm, "new Temporal.PlainTime(13, 30).since(new Temporal.PlainTime(12, 30)).toString()").unwrap();
+    assert_eq!(str_val(&vm, r), "PT1H");
+    let r = eval(
+        &mut vm,
+        "new Temporal.PlainTime(12, 30).until(new Temporal.PlainTime(13, 30, 5, 500)).toString()",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "PT1H5.5S");
+}
+
+#[test]
+fn plain_time_until_since_options_and_direction() {
+    let mut vm = Vm::new();
+    let r = eval(
+        &mut vm,
+        "new Temporal.PlainTime(12, 30).until(new Temporal.PlainTime(13, 35), { largestUnit: 'minute' }).toString()",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "PT65M");
+    let r = eval(
+        &mut vm,
+        "new Temporal.PlainTime(12, 30).since(new Temporal.PlainTime(13, 35), { largestUnit: 'minute' }).toString()",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "-PT65M");
+    let r = eval(
+        &mut vm,
+        "new Temporal.PlainTime(12, 30).until(new Temporal.PlainTime(13, 30), { smallestUnit: 'hour' }).toString()",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "PT1H");
+}
+
 // -- Temporal.PlainDateTime --
 
 #[test]