feat: implement Temporal PlainDateTime conversion and serialization

crates/oxide_vm/src/bindings/bind_temporal.rs

@@ -394,6 +394,19 @@ pub fn bind_temporal(core: &Arc<KernelCore>, session: &KernelSession, global: &m
         .map_or(0, |props| props.len() as u32)
         .saturating_sub(1);
     plain_date_time_ctor.set_data_meta(length_pos, PropAttributes::new(false, false, true));
+    apply_binding_table(
+        world,
+        plain_date_time_ctor,
+        core,
+        &[
+            ("from", oxide_builtins::temporal::plain_date_time_from::<crate::vm::Vm> as *const (), 1),
+            (
+                "compare",
+                oxide_builtins::temporal::plain_date_time_compare::<crate::vm::Vm> as *const (),
+                2,
+            ),
+        ],
+    );
     let plain_date_time_proto_ptr = world.plain_date_time_proto.as_ptr() as *mut JsObject;
     let plain_date_time_proto = unsafe { &mut *plain_date_time_proto_ptr };
     for (name, getter) in [
@@ -487,6 +500,16 @@ pub fn bind_temporal(core: &Arc<KernelCore>, session: &KernelSession, global: &m
                 oxide_builtins::temporal::plain_date_time_value_of::<crate::vm::Vm> as *const (),
                 0,
             ),
+            (
+                "toString",
+                oxide_builtins::temporal::plain_date_time_to_string::<crate::vm::Vm> as *const (),
+                0,
+            ),
+            (
+                "toJSON",
+                oxide_builtins::temporal::plain_date_time_to_json::<crate::vm::Vm> as *const (),
+                0,
+            ),
         ],
     );
     bind_well_known_data_property(

crates/oxide_vm/tests/builtins_temporal_tests.rs

@@ -686,3 +686,47 @@ fn plain_date_time_metadata_and_value_of() {
     .unwrap();
     assert_eq!(str_val(&vm, r), "3,true,[object Temporal.PlainDateTime],TypeError");
 }
+
+#[test]
+fn plain_date_time_from_instances_strings_and_objects() {
+    let mut vm = Vm::new();
+    let r = eval(
+        &mut vm,
+        "let original = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 1, 123, 456);
+         let copy = Temporal.PlainDateTime.from(original);
+         let parsed = Temporal.PlainDateTime.from('1976-11-18T15:23:30.001123456');
+         let bag = Temporal.PlainDateTime.from({year: 1976, monthCode: 'M11', day: 18, hour: 15});
+         (copy !== original) + ',' + parsed.toString() + ',' + bag.toString()",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "true,1976-11-18T15:23:30.001123456,1976-11-18T15:00:00");
+}
+
+#[test]
+fn plain_date_time_compare_uses_internal_slots() {
+    let mut vm = Vm::new();
+    let r = eval(
+        &mut vm,
+        "let earlier = new Temporal.PlainDateTime(2000, 5, 2, 12, 34, 56);
+         let later = new Temporal.PlainDateTime(2000, 5, 2, 12, 34, 57);
+         Object.defineProperty(earlier, 'year', {get() { throw new Error('getter') }});
+         Object.defineProperty(later, 'year', {get() { throw new Error('getter') }});
+         Temporal.PlainDateTime.compare(earlier, later) + ',' +
+         Temporal.PlainDateTime.compare(later, earlier) + ',' +
+         Temporal.PlainDateTime.compare(earlier, earlier)",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "-1,1,0");
+}
+
+#[test]
+fn plain_date_time_serializes_extended_years() {
+    let mut vm = Vm::new();
+    let r = eval(
+        &mut vm,
+        "new Temporal.PlainDateTime(-1, 8, 7, 6, 54, 32, 100).toString() + ',' +
+         new Temporal.PlainDateTime(10000, 6, 7, 8, 9, 10, 987).toJSON()",
+    )
+    .unwrap();
+    assert_eq!(str_val(&vm, r), "-000001-08-07T06:54:32.1,+010000-06-07T08:09:10.987");
+}