diff --git a/crates/oxide_builtins/src/temporal/difference.rs b/crates/oxide_builtins/src/temporal/difference.rs
index b794830d..cb30ef9f 100644
--- a/crates/oxide_builtins/src/temporal/difference.rs
+++ b/crates/oxide_builtins/src/temporal/difference.rs
@@ -77,6 +77,41 @@ pub(crate) const DAY_NS: i128 = 86_400_000_000_000;
 
 pub(crate) const MAX_ISO_DAY: i128 = 100_000_000;
 
+/// 时间单位长度表（时到纳秒，下标 = 单位索引 - 4）。
+pub(crate) const TIME_UNIT_NS: [i128; 6] = [3_600_000_000_000, 60_000_000_000, 1_000_000_000, 1_000_000, 1_000, 1];
+
+/// 内部时长记录：日期部分（年/月/周/日）加时间部分（纳秒，不含日分量）。
+pub(crate) struct InternalDuration {
+    pub(crate) date: [f64; 4],
+    pub(crate) time_ns: i128,
+}
+
+impl InternalDuration {
+    /// 转十分量数组：时间部分按向零截断分解为时/分/秒/毫秒/微秒/纳秒（与时长同号）。
+    pub(crate) fn to_values(&self) -> [f64; 10] {
+        let mut values = [0.0; 10];
+        values[0..4].copy_from_slice(&self.date);
+        let time = plain_time_components_signed(self.time_ns);
+        for index in 0..6 {
+            values[4 + index] = time[index] as f64;
+        }
+        values
+    }
+}
+
+/// InternalDurationSign（规范 7.5.15）：日期部分符号优先，其次时间部分符号。
+pub(crate) fn internal_duration_sign(values: &[f64; 10]) -> i128 {
+    let date_sign = date_duration_sign(values);
+    if date_sign != 0 {
+        return date_sign;
+    }
+    match super::duration::duration_time_only_nanoseconds(values) {
+        Some(time_ns) if time_ns < 0 => -1,
+        Some(time_ns) if time_ns > 0 => 1,
+        _ => 0,
+    }
+}
+
 /// 比较两个 ISO 日期，返回 -1/0/+1。
 pub(crate) fn compare_iso_date(a: (i128, i128, i128), b: (i128, i128, i128)) -> i128 {
     if a.0 != b.0 {
@@ -345,13 +380,25 @@ pub(crate) fn nudge_window(
     (r1, r2, start, end)
 }
 
+/// NudgeToCalendarUnit 结果：取整后时长、取整后纪元、窗口是否扩窗（或取整到上界），
+/// 以及以取整单位计的分数总量（窗口端点间的相对位置）。
+pub(crate) struct NudgeCalendarResult {
+    pub(crate) duration: [f64; 10],
+    pub(crate) nudged_epoch: i128,
+    pub(crate) did_expand: bool,
+    pub(crate) total: f64,
+}
+
 /// 对年/月/周单位的差值取整：把候选窗口端点换算成纪元纳秒，按目标时刻在窗口
 /// 中的相对位置决定取整方向（NudgeToCalendarUnit 语义）。
+///
+/// `epoch_of_date` 是窗口端点日期的纪元换算闭包：plain 面传墙钟换算（行为逐字节
+/// 不变），zoned 面传 GetEpochNanosecondsFor(compatible) 换算。
 #[allow(clippy::too_many_arguments)]
-fn nudge_to_calendar_unit(
-    sign: i128, values: &[f64; 10], origin_epoch: i128, dest_epoch: i128, date1: (i128, i128, i128), time1_ns: i128,
-    increment: i128, unit: usize, mode: InstantRoundingMode,
-) -> Result<([f64; 10], i128, bool), ()> {
+pub(crate) fn nudge_to_calendar_unit(
+    sign: i128, values: &[f64; 10], origin_epoch: i128, dest_epoch: i128, date1: (i128, i128, i128), increment: i128,
+    unit: usize, mode: InstantRoundingMode, epoch_of_date: &dyn Fn((i128, i128, i128)) -> Result<i128, ()>,
+) -> Result<NudgeCalendarResult, ()> {
     let epoch_of = |dur: &[f64; 10]| -> Result<i128, ()> {
         if date_duration_sign(dur) == 0 {
             return Ok(origin_epoch);
@@ -361,7 +408,7 @@ fn nudge_to_calendar_unit(
         if days.abs() > MAX_ISO_DAY {
             return Err(());
         }
-        Ok(days * DAY_NS + time1_ns)
+        epoch_of_date(date)
     };
     let mut did_expand = false;
     let (mut r1, mut r2, mut start_dur, mut end_dur) = nudge_window(sign, values, date1, increment, unit, false);
@@ -400,14 +447,24 @@ fn nudge_to_calendar_unit(
     did_expand = did_expand || rounded_unit == r2.abs();
     let duration = if rounded_unit == r2.abs() { end_dur } else { start_dur };
     let nudged = if did_expand { end_epoch } else { start_epoch };
-    Ok((duration, nudged, did_expand))
+    // 分数总量：r1 加窗口内相对位置（increment 为 1 时即规范 [[Total]]）。
+    let total = (denominator as f64 * r1 as f64 + numerator as f64 * sign as f64) / denominator as f64;
+    Ok(NudgeCalendarResult {
+        duration,
+        nudged_epoch: nudged,
+        did_expand,
+        total,
+    })
 }
 
 /// 舍入结果越过小单位边界时向更大的单位逐级进位，并把被进位单位的低位分量
 /// 清零，最多进位到 largest 指定的单位（BubbleRelativeDuration 语义）。
-fn bubble_relative_duration(
-    sign: i128, mut values: [f64; 10], nudged_epoch: i128, date1: (i128, i128, i128), time1_ns: i128, largest: usize,
-    start_unit: usize,
+///
+/// `epoch_of_date` 是进位候选日期的纪元换算闭包：plain 面传墙钟换算（行为逐字节
+/// 不变），zoned 面传 GetEpochNanosecondsFor(compatible) 换算。
+pub(crate) fn bubble_relative_duration(
+    sign: i128, mut values: [f64; 10], nudged_epoch: i128, date1: (i128, i128, i128), largest: usize,
+    start_unit: usize, epoch_of_date: &dyn Fn((i128, i128, i128)) -> Result<i128, ()>,
 ) -> Result<[f64; 10], ()> {
     if start_unit == 0 {
         return Ok(values);
@@ -446,7 +503,7 @@ fn bubble_relative_duration(
             let end_date = add_date_duration(date1, &end_dur);
             // 进位候选边界可能越出 ISO 日期范围，仅用于换算比较用的纪元纳秒并判断
             // 是否进位，因此这里不做范围校验。
-            let end_epoch = days_from_civil(end_date.0, end_date.1, end_date.2) * DAY_NS + time1_ns;
+            let end_epoch = epoch_of_date(end_date)?;
             let reached_end = if sign > 0 { nudged_epoch >= end_epoch } else { nudged_epoch <= end_epoch };
             if reached_end {
                 values = end_dur;
@@ -742,6 +799,10 @@ pub(crate) fn nudge_iso_difference<H: VmHost>(
 
     let date1 = start;
     let time1_ns = start_time_ns;
+    // plain 面纪元换算闭包：墙钟（日 × 24h + 时间），行为与旧内联算法逐字节一致。
+    let epoch_of_date = |date: (i128, i128, i128)| -> Result<i128, ()> {
+        Ok(days_from_civil(date.0, date.1, date.2) * DAY_NS + time1_ns)
+    };
     let mut date2 = end;
     let mut time_ns = end_time_ns - time1_ns;
     let time_sign = if time_ns > 0 {
@@ -830,7 +891,7 @@ pub(crate) fn nudge_iso_difference<H: VmHost>(
         }
         if did_expand_days {
             let nudged = dest_epoch + (rounded_ns - total_ns);
-            match bubble_relative_duration(sign, values, nudged, date1, time1_ns, largest_index, 3) {
+            match bubble_relative_duration(sign, values, nudged, date1, largest_index, 3, &epoch_of_date) {
                 Ok(bubbled) => values = bubbled,
                 Err(()) => return Err(crate::error::create_range_error(vm, "difference is out of range")),
             }
@@ -839,22 +900,33 @@ pub(crate) fn nudge_iso_difference<H: VmHost>(
     } else {
         // year/month/week 长度随日历变化，无法折算成固定纳秒：改用纪元纳秒窗口
         // 取整，按目标时刻落在候选窗口内的相对位置决定取整方向（NudgeToCalendarUnit 语义）。
-        let (mut values, nudged_epoch, did_expand) = match nudge_to_calendar_unit(
+        let outcome = match nudge_to_calendar_unit(
             sign,
             &date_values,
             origin_epoch,
             dest_epoch,
             date1,
-            time1_ns,
             increment,
             smallest_index,
             mode,
+            &epoch_of_date,
         ) {
             Ok(result) => result,
             Err(()) => return Err(crate::error::create_range_error(vm, "difference is out of range")),
         };
+        let mut values = outcome.duration;
+        let nudged_epoch = outcome.nudged_epoch;
+        let did_expand = outcome.did_expand;
         if did_expand && smallest_index != 2 {
-            match bubble_relative_duration(sign, values, nudged_epoch, date1, time1_ns, largest_index, smallest_index) {
+            match bubble_relative_duration(
+                sign,
+                values,
+                nudged_epoch,
+                date1,
+                largest_index,
+                smallest_index,
+                &epoch_of_date,
+            ) {
                 Ok(bubbled) => values = bubbled,
                 Err(()) => return Err(crate::error::create_range_error(vm, "difference is out of range")),
             }
diff --git a/crates/oxide_builtins/src/temporal/duration.rs b/crates/oxide_builtins/src/temporal/duration.rs
index 190350dc..3fff94d1 100644
--- a/crates/oxide_builtins/src/temporal/duration.rs
+++ b/crates/oxide_builtins/src/temporal/duration.rs
@@ -13,12 +13,14 @@ use super::common::{
     zoned_date_time_plain_parts,
 };
 use super::difference::{
-    add_date_duration, add_days_iso, compare_iso_date, date_duration_sign, date_until_iso, nudge_iso_difference,
-    nudge_window, plain_date_time_unit_index, round_instant_difference, DifferenceSettings, DAY_NS, MAX_ISO_DAY,
+    add_date_duration, add_days_iso, balance_instant_difference, compare_iso_date, date_duration_sign, date_until_iso,
+    nudge_iso_difference, nudge_window, plain_date_time_unit_index, round_instant_difference, DifferenceSettings,
+    InternalDuration, DAY_NS, MAX_ISO_DAY,
 };
 use super::instant::{instant_rounding_mode, InstantRoundingMode};
 use super::time_zone::zone_offset_seconds;
 use super::zoned_date_time::{
+    add_zoned_datetime, difference_zoned_datetime_with_rounding_vm, difference_zoned_datetime_with_total_vm,
     extract_time_zone_annotation, parse_any_offset_seconds, valid_offset_fraction, zoned_date_time_string_parts,
 };
 use super::{make_duration, parse_plain_date_time_string};
@@ -299,15 +301,13 @@ fn duration_values(obj: &JsObject) -> [f64; 10] {
 enum RelativePoint {
     Wall {
         date: (i128, i128, i128),
-        /// 本批调用方只消费日期，zoned epoch 路径消费日历。
+        /// 当前仅 iso8601 日历，zoned 路径不消费日历。
         #[allow(dead_code)]
         calendar: String,
     },
     Zoned {
         epoch_ns: i128,
         time_zone: String,
-        /// 本批调用方只消费 epoch 与时区，zoned epoch 路径消费日历。
-        #[allow(dead_code)]
         calendar: String,
     },
 }
@@ -319,8 +319,7 @@ enum RelativePoint {
 /// 2. Zoned → 区偏移（epoch 依赖查找）+ civil_from_days 反推墙历日期。
 ///
 /// # 边界与前提
-/// - Zoned 支是本批过渡路径（TODO: 69.3.4.2 切 epoch 路径），算法与旧 zoned
-///   字符串支保持逐字节一致。
+/// - Zoned 支仅用于 compare 的两支纯时间落回路径（24h 语义与规范 plain 路径一致）。
 fn relative_point_wall_date<H: VmHost>(vm: &mut H, point: &RelativePoint) -> Result<(i128, i128, i128), JsValue> {
     match point {
         RelativePoint::Wall { date, .. } => Ok(*date),
@@ -548,6 +547,15 @@ pub fn duration_total<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
         Err(error) => return NativeResult::Err(error),
     };
 
+    // Zoned 载荷：AddZonedDateTime → DifferenceZonedDateTimeWithTotal（门与单位无关）。
+    if let Some(RelativePoint::Zoned { epoch_ns, time_zone, calendar }) = &relative_date {
+        let target = native_try!(add_zoned_datetime(vm, *epoch_ns, time_zone, calendar, &values, true));
+        let total = native_try!(difference_zoned_datetime_with_total_vm(
+            vm, *epoch_ns, target, time_zone, calendar, unit_index
+        ));
+        return NativeResult::Ok(JsValue::float(total));
+    }
+
     const UNIT_NS: [i128; 6] = [3_600_000_000_000, 60_000_000_000, 1_000_000_000, 1_000_000, 1_000, 1];
     if unit_index <= 2 || (unit_index == 3 && has_calendar_units) {
         // 日历单位：需要 relativeTo，用纪元纳秒窗口计算分数总量。
@@ -557,7 +565,6 @@ pub fn duration_total<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
                 &format!("a starting point is required for {} total", unit_raw),
             ));
         };
-        // Zoned 载荷暂走墙钟路径（TODO: 69.3.4.2 切 epoch 路径）。
         let rel_date = native_try!(relative_point_wall_date(vm, &point));
         let Some(time_ns_base) = duration_time_nanoseconds(&values) else {
             return NativeResult::Err(crate::error::create_range_error(vm, "duration is out of range"));
@@ -900,6 +907,52 @@ fn duration_apply_to_relative<H: VmHost>(
     Ok((end, target_time))
 }
 
+/// DefaultTemporalLargestUnit（规范 7.5.17）：首个非零分量索引（全零视为 nanosecond）。
+pub(crate) fn default_temporal_largest_unit(values: &[f64; 10]) -> usize {
+    for (index, value) in values.iter().enumerate() {
+        if *value != 0.0 {
+            return index;
+        }
+    }
+    9
+}
+
+/// TemporalDurationFromInternal（规范 7.5.8）：日期部分直传，时间部分按 largestUnit 平衡。
+///
+/// # 步骤
+/// 1. largestUnit 为日期类（day 及以上）：时间全量分解，days 折回日期部分。
+/// 2. largestUnit 为时间类：从该单位向下分解。
+pub(crate) fn internal_duration_to_values(internal: &InternalDuration, largest: usize) -> [f64; 10] {
+    let mut values = [0.0; 10];
+    values[0..4].copy_from_slice(&internal.date);
+    let sign = if internal.time_ns < 0 { -1 } else { 1 };
+    if largest <= 3 {
+        let mut remainder = internal.time_ns.unsigned_abs();
+        let hours = remainder / 3_600_000_000_000;
+        remainder %= 3_600_000_000_000;
+        let minutes = remainder / 60_000_000_000;
+        remainder %= 60_000_000_000;
+        let seconds = remainder / 1_000_000_000;
+        remainder %= 1_000_000_000;
+        let milliseconds = remainder / 1_000_000;
+        remainder %= 1_000_000;
+        let microseconds = remainder / 1_000;
+        let nanoseconds = remainder % 1_000;
+        let days = hours / 24;
+        values[3] = internal.date[3] + sign as f64 * days as f64;
+        values[4] = (hours % 24) as f64 * sign as f64;
+        values[5] = minutes as f64 * sign as f64;
+        values[6] = seconds as f64 * sign as f64;
+        values[7] = milliseconds as f64 * sign as f64;
+        values[8] = microseconds as f64 * sign as f64;
+        values[9] = nanoseconds as f64 * sign as f64;
+    } else {
+        let time_values = balance_instant_difference(internal.time_ns, largest - 4).unwrap_or([0.0; 10]);
+        values[4..10].copy_from_slice(&time_values[4..10]);
+    }
+    values
+}
+
 /// `Temporal.Duration.compare(one, two, options)`：按相对点比较两个时长。
 ///
 /// # 步骤
@@ -957,8 +1010,22 @@ pub fn duration_compare<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
             one_ns.cmp(&two_ns)
         }
         Some(point) => {
+            // Zoned 载荷且任一支最大单位为日期类：epoch 级比较（门是 OR）。
+            // 两支均纯时间时落回 24h 墙钟路径（与规范 plain 路径一致）。
+            if let RelativePoint::Zoned { epoch_ns, time_zone, calendar } = &point {
+                let largest1 = default_temporal_largest_unit(&one);
+                let largest2 = default_temporal_largest_unit(&two);
+                if largest1 <= 3 || largest2 <= 3 {
+                    let after1 = native_try!(add_zoned_datetime(vm, *epoch_ns, time_zone, calendar, &one, true));
+                    let after2 = native_try!(add_zoned_datetime(vm, *epoch_ns, time_zone, calendar, &two, true));
+                    return NativeResult::Ok(JsValue::int(match after1.cmp(&after2) {
+                        std::cmp::Ordering::Less => -1,
+                        std::cmp::Ordering::Equal => 0,
+                        std::cmp::Ordering::Greater => 1,
+                    }));
+                }
+            }
             // 有 relativeTo：各 duration 应用后先比日期再比时间。
-            // Zoned 载荷暂走墙钟路径（TODO: 69.3.4.2 切 epoch 路径）。
             let rel = native_try!(relative_point_wall_date(vm, &point));
             let (date1, time1) = native_try!(duration_apply_to_relative(vm, rel, &one));
             let (date2, time2) = native_try!(duration_apply_to_relative(vm, rel, &two));
@@ -1136,7 +1203,30 @@ pub fn duration_round<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
     };
 
     // 日历单位存在或目标为日历单位时走 relativeTo 路径，否则走纯时间路径。
-    let needs_relative = values[..3].iter().any(|value| *value != 0.0) || largest < 3 || smallest_index < 3;
+    // Zoned 相对点无条件走 zoned 路径（DST 感知的日长，24h 路径失准）。
+    let needs_relative = values[..3].iter().any(|value| *value != 0.0)
+        || largest < 3
+        || smallest_index < 3
+        || matches!(&relative_date, Some(RelativePoint::Zoned { .. }));
+    // Zoned 载荷：AddZonedDateTime → DifferenceZonedDateTimeWithRounding（门与单位无关）。
+    if let Some(RelativePoint::Zoned { epoch_ns, time_zone, calendar }) = &relative_date {
+        let target = native_try!(add_zoned_datetime(vm, *epoch_ns, time_zone, calendar, &values, true));
+        let internal = native_try!(difference_zoned_datetime_with_rounding_vm(
+            vm,
+            *epoch_ns,
+            target,
+            time_zone,
+            calendar,
+            largest,
+            increment,
+            smallest_index,
+            mode,
+        ));
+        // largestUnit 为日期类时降为 hour。
+        let largest = if largest <= 3 { 4 } else { largest };
+        let result = internal_duration_to_values(&internal, largest);
+        return make_duration(vm, result);
+    }
     if !needs_relative {
         // 纯时间路径：按 24 小时/天将 days..nanoseconds 汇总为纳秒，按 smallest 舍入后平衡到 largest。
         let Some(time_ns) = duration_time_nanoseconds(&values) else {
@@ -1194,7 +1284,6 @@ pub fn duration_round<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
             "a starting point is required for rounding calendar units",
         ));
     };
-    // Zoned 载荷暂走墙钟路径（TODO: 69.3.4.2 切 epoch 路径）。
     let rel = native_try!(relative_point_wall_date(vm, &point));
     let Some(time_ns_total) = duration_time_nanoseconds(&values) else {
         return NativeResult::Err(crate::error::create_range_error(vm, "duration is out of range"));
diff --git a/crates/oxide_builtins/src/temporal/tests.rs b/crates/oxide_builtins/src/temporal/tests.rs
index 999fa71e..c411cefa 100644
--- a/crates/oxide_builtins/src/temporal/tests.rs
+++ b/crates/oxide_builtins/src/temporal/tests.rs
@@ -619,3 +619,108 @@ fn calendar_date_add_iso_constrain_semantics() {
     // 闰年二月：constrain 钳到 29。
     assert_eq!(calendar_date_add_iso((2024, 1, 31), 0, 1, 0, 0, true), Ok((2024, 2, 29)));
 }
+
+#[test]
+fn zoned_difference_day_correction() {
+    use super::zoned_date_time::{difference_zoned_datetime, get_epoch_nanos_for};
+
+    // 同日纯时间差：无日期部分，时间部分为纳秒差。
+    let ns1 = get_epoch_nanos_for("America/New_York", (2025, 6, 15), 43_200_000_000_000).unwrap();
+    let ns2 = get_epoch_nanos_for("America/New_York", (2025, 6, 15), 66_600_000_000_000).unwrap();
+    let d = difference_zoned_datetime(ns1, ns2, "America/New_York", "iso8601", 3).unwrap();
+    assert_eq!(d.date, [0.0, 0.0, 0.0, 0.0]);
+    assert_eq!(d.time_ns, 23_400_000_000_000);
+
+    // 跨 DST 间隙日（23 小时）：墙历时刻相同，日期部分 1 天、时间部分 0。
+    let ns1 = get_epoch_nanos_for("America/New_York", (2025, 3, 8), 43_200_000_000_000).unwrap();
+    let ns2 = get_epoch_nanos_for("America/New_York", (2025, 3, 9), 43_200_000_000_000).unwrap();
+    let d = difference_zoned_datetime(ns1, ns2, "America/New_York", "iso8601", 3).unwrap();
+    assert_eq!(d.date, [0.0, 0.0, 0.0, 1.0]);
+    assert_eq!(d.time_ns, 0);
+
+    // dayCorrection 循环推进：12 小时跨间隙日，日期部分 0、时间部分 12 小时。
+    let ns2b = get_epoch_nanos_for("America/New_York", (2025, 3, 9), 0).unwrap();
+    let d = difference_zoned_datetime(ns1, ns2b, "America/New_York", "iso8601", 3).unwrap();
+    assert_eq!(d.date, [0.0, 0.0, 0.0, 0.0]);
+    assert_eq!(d.time_ns, 43_200_000_000_000);
+
+    // 反向（sign 为正）：日期部分为负一天、时间部分 0。
+    let d = difference_zoned_datetime(ns2, ns1, "America/New_York", "iso8601", 3).unwrap();
+    assert_eq!(d.date, [0.0, 0.0, 0.0, -1.0]);
+    assert_eq!(d.time_ns, 0);
+}
+
+#[test]
+fn zoned_total_dst_fraction() {
+    use super::zoned_date_time::{difference_zoned_datetime_with_total, get_epoch_nanos_for};
+
+    // 整日差（23 小时间隙日）：总量 1。
+    let ns1 = get_epoch_nanos_for("America/New_York", (2025, 3, 8), 43_200_000_000_000).unwrap();
+    let ns2 = get_epoch_nanos_for("America/New_York", (2025, 3, 9), 43_200_000_000_000).unwrap();
+    let total = difference_zoned_datetime_with_total(ns1, ns2, "America/New_York", "iso8601", 3).unwrap();
+    assert!((total - 1.0).abs() < 1e-12);
+
+    // 12 小时跨 23 小时间隙日：总量 12/23（按实际日长折算，非 24 小时）。
+    let ns2b = get_epoch_nanos_for("America/New_York", (2025, 3, 9), 0).unwrap();
+    let total = difference_zoned_datetime_with_total(ns1, ns2b, "America/New_York", "iso8601", 3).unwrap();
+    assert!((total - 12.0 / 23.0).abs() < 1e-12);
+}
+
+#[test]
+fn zoned_round_nudge_to_zoned_time() {
+    use super::duration::internal_duration_to_values;
+    use super::instant::InstantRoundingMode;
+    use super::zoned_date_time::{
+        add_zoned_datetime_pure, difference_zoned_datetime_with_rounding, get_epoch_nanos_for,
+    };
+
+    // Apia 2011-12-30 整日跳过（24 小时间隙）：起点墙历为 12-31 00:30。
+    let origin = get_epoch_nanos_for("Pacific/Apia", (2011, 12, 30), 1_800_000_000_000).unwrap();
+
+    // P25H 按小时取整：跨间隙日不产生进位，保持 25 小时（非 1 天 1 小时）。
+    let p25h = [0.0_f64, 0.0, 0.0, 0.0, 25.0, 0.0, 0.0, 0.0, 0.0, 0.0];
+    let target = add_zoned_datetime_pure(origin, "Pacific/Apia", "iso8601", &p25h, true).unwrap();
+    let internal = difference_zoned_datetime_with_rounding(
+        origin,
+        target,
+        "Pacific/Apia",
+        "iso8601",
+        4,
+        1,
+        4,
+        InstantRoundingMode::Trunc,
+    )
+    .unwrap();
+    let values = internal_duration_to_values(&internal, 4);
+    assert_eq!(values, [0.0, 0.0, 0.0, 0.0, 25.0, 0.0, 0.0, 0.0, 0.0, 0.0]);
+
+    // P1DT26H 按小时取整：日长 24 小时，取整后 2 天 2 小时。
+    let p1dt26h = [0.0_f64, 0.0, 0.0, 1.0, 26.0, 0.0, 0.0, 0.0, 0.0, 0.0];
+    let target = add_zoned_datetime_pure(origin, "Pacific/Apia", "iso8601", &p1dt26h, true).unwrap();
+    let internal = difference_zoned_datetime_with_rounding(
+        origin,
+        target,
+        "Pacific/Apia",
+        "iso8601",
+        3,
+        1,
+        4,
+        InstantRoundingMode::Trunc,
+    )
+    .unwrap();
+    let values = internal_duration_to_values(&internal, 4);
+    assert_eq!(values, [0.0, 0.0, 0.0, 2.0, 2.0, 0.0, 0.0, 0.0, 0.0, 0.0]);
+}
+
+#[test]
+fn zoned_compare_pure_epoch() {
+    use super::zoned_date_time::{add_zoned_datetime_pure, get_epoch_nanos_for};
+
+    // 跨 23 小时间隙日：P1D（实际 23 小时）短于 P24H（实际 24 小时）。
+    let origin = get_epoch_nanos_for("America/New_York", (2025, 3, 8), 43_200_000_000_000).unwrap();
+    let p1d = [0.0_f64, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0];
+    let p24h = [0.0_f64, 0.0, 0.0, 0.0, 24.0, 0.0, 0.0, 0.0, 0.0, 0.0];
+    let after1d = add_zoned_datetime_pure(origin, "America/New_York", "iso8601", &p1d, true).unwrap();
+    let after24h = add_zoned_datetime_pure(origin, "America/New_York", "iso8601", &p24h, true).unwrap();
+    assert!(after1d < after24h);
+}
diff --git a/crates/oxide_builtins/src/temporal/zoned_date_time.rs b/crates/oxide_builtins/src/temporal/zoned_date_time.rs
index 2ec9d930..4b9b34f6 100644
--- a/crates/oxide_builtins/src/temporal/zoned_date_time.rs
+++ b/crates/oxide_builtins/src/temporal/zoned_date_time.rs
@@ -17,17 +17,19 @@ use super::common::{
     zoned_date_time_plain_parts, FractionalSecondDigitsInput, MAX_INSTANT_NS,
 };
 use super::difference::{
-    add_days_iso, date_duration_sign, difference_core, parse_difference_settings, DAY_NS, MAX_ISO_DAY,
+    add_days_iso, bubble_relative_duration, compare_iso_date, date_duration_sign, date_until_iso, difference_core,
+    internal_duration_sign, nudge_to_calendar_unit, parse_difference_settings, round_instant_difference,
+    InternalDuration, DAY_NS, MAX_ISO_DAY, TIME_UNIT_NS,
 };
 use super::instant::{
     instant_rounding_mode, instant_string_without_annotations, parse_instant_string, primitive_to_bigint,
-    round_instant_ns,
+    round_instant_ns, InstantRoundingMode,
 };
 use super::time_zone::{named_zone_possible_epoch_ns, tz_gap_offsets, zone_offset_seconds};
 use super::{
     days_in_month_iso, duration_like_values, duration_time_only_nanoseconds, is_leap_year_iso, make_duration,
-    make_plain_date, make_plain_date_time, make_plain_time, plain_time_components, plain_time_like_ns, valid_iso_date,
-    valid_plain_date_time_range,
+    make_plain_date, make_plain_date_time, make_plain_time, plain_time_components, plain_time_components_signed,
+    plain_time_like_ns, valid_iso_date, valid_plain_date_time_range,
 };
 
 /// `Temporal.ZonedDateTime` 构造器：保存纪元纳秒、固定偏移或 UTC 时区以及 ISO 日历。
@@ -1835,12 +1837,7 @@ pub(crate) fn add_zoned_datetime_pure(
         return add_instant(epoch_ns, time_ns);
     }
     // GetISODateTimeFor：墙历分量。
-    let offset_seconds = zone_offset_seconds(time_zone, epoch_ns.div_euclid(1_000_000_000) as i64)
-        .ok_or(AddZonedError::InvalidTimeZone)?;
-    let local_ns = epoch_ns + i128::from(offset_seconds) * 1_000_000_000;
-    let days = local_ns.div_euclid(DAY_NS);
-    let time_ns = local_ns.rem_euclid(DAY_NS);
-    let (year, month, day) = civil_from_days(days);
+    let ((year, month, day), time_ns) = get_iso_date_time_for(time_zone, epoch_ns)?;
     if !valid_plain_date_time_range(year as i32, month as u32, day as u32, time_ns as f64) {
         return Err(AddZonedError::OutOfDateTimeRange);
     }
@@ -1868,10 +1865,16 @@ pub(crate) fn add_zoned_datetime_pure(
 }
 
 /// AddZonedDateTime 的 VM 包装：核心错误统一转 RangeError。
-fn add_zoned_datetime<H: VmHost>(
+pub(crate) fn add_zoned_datetime<H: VmHost>(
     vm: &mut H, epoch_ns: i128, time_zone: &str, calendar: &str, values: &[f64; 10], constrain: bool,
 ) -> Result<i128, JsValue> {
-    add_zoned_datetime_pure(epoch_ns, time_zone, calendar, values, constrain).map_err(|error| match error {
+    add_zoned_datetime_pure(epoch_ns, time_zone, calendar, values, constrain)
+        .map_err(|error| map_add_zoned_error(vm, error))
+}
+
+/// AddZonedError 到 JS RangeError 的映射（各 zoned 面 VM 包装共用）。
+fn map_add_zoned_error<H: VmHost>(vm: &mut H, error: AddZonedError) -> JsValue {
+    match error {
         AddZonedError::InvalidTimeZone => crate::error::create_range_error(vm, "invalid time zone"),
         AddZonedError::OutOfDateTimeRange => crate::error::create_range_error(vm, "invalid date-time"),
         AddZonedError::OutOfInstantRange => {
@@ -1880,9 +1883,327 @@ fn add_zoned_datetime<H: VmHost>(
         AddZonedError::DayOutOfRange => crate::error::create_range_error(vm, "day out of range"),
         AddZonedError::InvalidDate => crate::error::create_range_error(vm, "invalid date"),
         AddZonedError::OutOfTimeRange => crate::error::create_range_error(vm, "duration is out of range"),
+    }
+}
+
+/// DifferenceZonedDateTimeWithRounding 的 VM 包装：错误映射为 RangeError。
+#[allow(clippy::too_many_arguments)]
+pub(crate) fn difference_zoned_datetime_with_rounding_vm<H: VmHost>(
+    vm: &mut H, ns1: i128, ns2: i128, time_zone: &str, calendar: &str, largest_unit: usize, increment: i128,
+    smallest_unit: usize, mode: InstantRoundingMode,
+) -> Result<InternalDuration, JsValue> {
+    difference_zoned_datetime_with_rounding(ns1, ns2, time_zone, calendar, largest_unit, increment, smallest_unit, mode)
+        .map_err(|error| map_add_zoned_error(vm, error))
+}
+
+/// DifferenceZonedDateTimeWithTotal 的 VM 包装：错误映射为 RangeError。
+pub(crate) fn difference_zoned_datetime_with_total_vm<H: VmHost>(
+    vm: &mut H, ns1: i128, ns2: i128, time_zone: &str, calendar: &str, unit: usize,
+) -> Result<f64, JsValue> {
+    difference_zoned_datetime_with_total(ns1, ns2, time_zone, calendar, unit)
+        .map_err(|error| map_add_zoned_error(vm, error))
+}
+
+/// GetISODateTimeFor（规范 11.1.10）：epoch 对应的墙历日期时间。
+///
+/// # 步骤
+/// 1. 区偏移（epoch 依赖查找）加到 epoch 得墙历纳秒。
+/// 2. 拆日与时间（欧几里得除，负 epoch 同样正确）。
+///
+/// # 边界与前提
+/// - 时区名非法（不在区表且非固定偏移串）返回 InvalidTimeZone。
+pub(crate) fn get_iso_date_time_for(
+    time_zone: &str, epoch_ns: i128,
+) -> Result<((i128, i128, i128), i128), AddZonedError> {
+    let offset_seconds = zone_offset_seconds(time_zone, epoch_ns.div_euclid(1_000_000_000) as i64)
+        .ok_or(AddZonedError::InvalidTimeZone)?;
+    let local_ns = epoch_ns + i128::from(offset_seconds) * 1_000_000_000;
+    let days = local_ns.div_euclid(DAY_NS);
+    let time_ns = local_ns.rem_euclid(DAY_NS);
+    let (year, month, day) = civil_from_days(days);
+    Ok(((year, month, day), time_ns))
+}
+
+/// GetEpochNanosecondsFor（规范 11.1.11，compatible 消歧）：墙历日期时间的纪元。
+///
+/// # 步骤
+/// 1. 候选集（固定偏移区单候选；IANA 区 0/1/2 候选）。
+/// 2. compatible 消歧（重叠取早、间隙平移后取后侧）。
+///
+/// # 边界与前提
+/// - 日期年份越出 i32 表示范围视为越界（候选换算无意义）。
+/// - 候选超 Instant 范围或区表未命中返回对应错误。
+pub(crate) fn get_epoch_nanos_for(
+    time_zone: &str, date: (i128, i128, i128), time_ns: i128,
+) -> Result<i128, AddZonedError> {
+    if date.0 < i32::MIN as i128 || date.0 > i32::MAX as i128 {
+        return Err(AddZonedError::OutOfDateTimeRange);
+    }
+    let candidates = get_possible_epoch_nanoseconds(time_zone, date.0 as i32, date.1 as u32, date.2 as u32, time_ns)?;
+    disambiguate_possible_epoch_nanoseconds(time_zone, date, time_ns, "compatible", &candidates)
+}
+
+/// zoned 面纪元换算闭包工厂：候选日期 → (日期, time1) 的 GetEpochNanosecondsFor(compatible) 纪元。
+fn zoned_epoch_of_date<'a>(time_zone: &'a str, time1_ns: i128) -> impl Fn((i128, i128, i128)) -> Result<i128, ()> + 'a {
+    move |date| get_epoch_nanos_for(time_zone, date, time1_ns).map_err(|_| ())
+}
+
+/// 时间差纳秒的符号（-1/0/+1）。
+fn time_duration_sign(ns: i128) -> i128 {
+    if ns < 0 {
+        -1
+    } else if ns > 0 {
+        1
+    } else {
+        0
+    }
+}
+
+/// DifferenceZonedDateTime（规范 6.5.6）：两个 epoch 的差，平衡后结果中无大于
+/// largestUnit 的非零单位，计入日历 reckoning 与时区偏移变化。
+///
+/// # 步骤
+/// 1. 同墙历日 → 纯时间差（ZeroDateDuration + 纳秒差）。
+/// 2. dayCorrection 循环：按 sign 平移终点日期，经 GetEpochNanosecondsFor(compatible)
+///    取候选点，直到时间差符号与总差符号相反。
+/// 3. 日期部分按 CalendarDateUntil（largestUnit 与 day 取大者）分解。
+///
+/// # 边界与前提
+/// - 全程 i128 纳秒；中间点时间取起点墙历时间（规范 (intermediateDate, startDT.Time)）。
+/// - calendar 参数透传（引擎仅 iso8601 日历）。
+pub(crate) fn difference_zoned_datetime(
+    ns1: i128, ns2: i128, time_zone: &str, _calendar: &str, largest_unit: usize,
+) -> Result<InternalDuration, AddZonedError> {
+    if ns1 == ns2 {
+        return Ok(InternalDuration { date: [0.0; 4], time_ns: 0 });
+    }
+    let (start_date, start_time) = get_iso_date_time_for(time_zone, ns1)?;
+    let (end_date, end_time) = get_iso_date_time_for(time_zone, ns2)?;
+    if compare_iso_date(start_date, end_date) == 0 {
+        return Ok(InternalDuration {
+            date: [0.0; 4],
+            time_ns: ns2 - ns1,
+        });
+    }
+    let sign = if ns2 - ns1 < 0 { 1 } else { -1 };
+    let max_day_correction = if sign == -1 { 2 } else { 1 };
+    let mut day_correction = 0_i128;
+    let mut time_duration = end_time - start_time;
+    if time_duration_sign(time_duration) == sign {
+        day_correction += 1;
+    }
+    let mut success = false;
+    let mut intermediate_date = end_date;
+    while day_correction <= max_day_correction && !success {
+        intermediate_date = add_days_iso(end_date, day_correction * sign);
+        let intermediate_ns = get_epoch_nanos_for(time_zone, intermediate_date, start_time)?;
+        time_duration = ns2 - intermediate_ns;
+        if sign != time_duration_sign(time_duration) {
+            success = true;
+        }
+        day_correction += 1;
+    }
+    if !success {
+        return Err(AddZonedError::OutOfDateTimeRange);
+    }
+    let date_largest = largest_unit.min(3);
+    let date_values = date_until_iso(start_date, intermediate_date, date_largest);
+    Ok(InternalDuration {
+        date: [date_values[0], date_values[1], date_values[2], date_values[3]],
+        time_ns: time_duration,
     })
 }
 
+/// DifferenceZonedDateTimeWithRounding（规范 6.5.7）：两个 epoch 的差按设置取整。
+///
+/// # 步骤
+/// 1. largestUnit 为时间单位 → DifferenceInstant（8.5.6：纳秒差按单位取整）。
+/// 2. 否则 DifferenceZonedDateTime；smallestUnit 为 nanosecond 且 increment 为 1 时直接返回。
+/// 3. 否则 RoundRelativeDuration（zoned 路由）。
+///
+/// # 边界与前提
+/// - smallestUnit 不大于 largestUnit（调用方已校验）。
+#[allow(clippy::too_many_arguments)]
+pub(crate) fn difference_zoned_datetime_with_rounding(
+    ns1: i128, ns2: i128, time_zone: &str, _calendar: &str, largest_unit: usize, increment: i128, smallest_unit: usize,
+    mode: InstantRoundingMode,
+) -> Result<InternalDuration, AddZonedError> {
+    if largest_unit >= 4 {
+        let quantum = TIME_UNIT_NS[smallest_unit - 4]
+            .checked_mul(increment)
+            .ok_or(AddZonedError::OutOfTimeRange)?;
+        let rounded = round_instant_difference(ns2 - ns1, quantum, mode).ok_or(AddZonedError::OutOfTimeRange)?;
+        return Ok(InternalDuration {
+            date: [0.0; 4],
+            time_ns: rounded,
+        });
+    }
+    let difference = difference_zoned_datetime(ns1, ns2, time_zone, _calendar, largest_unit)?;
+    if smallest_unit == 9 && increment == 1 {
+        return Ok(difference);
+    }
+    let (iso_date, iso_time) = get_iso_date_time_for(time_zone, ns1)?;
+    round_relative_duration_zoned(
+        difference,
+        ns1,
+        ns2,
+        (iso_date, iso_time),
+        time_zone,
+        largest_unit,
+        increment,
+        smallest_unit,
+        mode,
+    )
+}
+
+/// RoundRelativeDuration（规范 7.5.38）的 zoned 路由：日历单位（或 day）走日历
+/// 窗口取整，时间单位走 NudgeToZonedTime；扩窗后进位到 largestUnit。
+///
+/// # 步骤
+/// 1. 路由：smallestUnit 为日历单位或 day → NudgeToCalendarUnit（zoned 闭包）；
+///    否则 NudgeToZonedTime。
+/// 2. 扩窗且 smallestUnit 非 week → BubbleRelativeDuration（startUnit 取 smallestUnit 与 day 的较大者）。
+#[allow(clippy::too_many_arguments)]
+fn round_relative_duration_zoned(
+    difference: InternalDuration, origin_ns: i128, dest_ns: i128, iso: ((i128, i128, i128), i128), time_zone: &str,
+    largest_unit: usize, increment: i128, smallest_unit: usize, mode: InstantRoundingMode,
+) -> Result<InternalDuration, AddZonedError> {
+    let values = difference.to_values();
+    let sign = if internal_duration_sign(&values) < 0 { -1 } else { 1 };
+    let (iso_date, iso_time) = iso;
+    let epoch_of_date = zoned_epoch_of_date(time_zone, iso_time);
+    // zoned 面时区恒在场：irregular = smallestUnit 为日历单位或 day。
+    let irregular = smallest_unit <= 3;
+    let (mut result, nudged_epoch, did_expand) = if irregular {
+        let outcome = nudge_to_calendar_unit(
+            sign,
+            &values,
+            origin_ns,
+            dest_ns,
+            iso_date,
+            increment,
+            smallest_unit,
+            mode,
+            &epoch_of_date,
+        )
+        .map_err(|_| AddZonedError::OutOfDateTimeRange)?;
+        (outcome.duration, outcome.nudged_epoch, outcome.did_expand)
+    } else {
+        nudge_to_zoned_time(sign, &values, iso_date, iso_time, time_zone, increment, smallest_unit, mode)?
+    };
+    if did_expand && smallest_unit != 2 {
+        let start_unit = smallest_unit.min(3);
+        result =
+            bubble_relative_duration(sign, result, nudged_epoch, iso_date, largest_unit, start_unit, &epoch_of_date)
+                .map_err(|_| AddZonedError::OutOfDateTimeRange)?;
+    }
+    Ok(InternalDuration {
+        date: [result[0], result[1], result[2], result[3]],
+        time_ns: duration_time_only_nanoseconds(&result).ok_or(AddZonedError::OutOfTimeRange)?,
+    })
+}
+
+/// NudgeToZonedTime（规范 7.5.35）：相对 zoned 起点按时间单位取整，计入日长
+/// 可能非 24 小时（DST 日）的情形。
+///
+/// # 步骤
+/// 1. start = CalendarDateAdd(constrain)；end = start 加 sign 天；两端点经
+///    GetEpochNanosecondsFor(compatible) 换算，daySpan 天然含 DST 日长。
+/// 2. 时间部分按 increment × 单位长度取整；越过日边界时记一天进位并重新取整余量。
+///
+/// # 边界与前提
+/// - unit 为时间单位（时到纳秒）；day 单位走日历窗口路径，不进本函数。
+#[allow(clippy::too_many_arguments)]
+fn nudge_to_zoned_time(
+    sign: i128, values: &[f64; 10], iso_date: (i128, i128, i128), iso_time: i128, time_zone: &str, increment: i128,
+    unit: usize, mode: InstantRoundingMode,
+) -> Result<([f64; 10], i128, bool), AddZonedError> {
+    let time_ns = duration_time_only_nanoseconds(values).ok_or(AddZonedError::OutOfTimeRange)?;
+    let start = calendar_date_add_iso(
+        iso_date,
+        values[0] as i128,
+        values[1] as i128,
+        values[2] as i128,
+        values[3] as i128,
+        true,
+    )?;
+    let start_epoch = get_epoch_nanos_for(time_zone, start, iso_time)?;
+    let end_epoch = get_epoch_nanos_for(time_zone, add_days_iso(start, sign), iso_time)?;
+    let day_span = end_epoch - start_epoch;
+    let quantum = TIME_UNIT_NS[unit - 4]
+        .checked_mul(increment)
+        .ok_or(AddZonedError::OutOfTimeRange)?;
+    let mut rounded = round_instant_difference(time_ns, quantum, mode).ok_or(AddZonedError::OutOfTimeRange)?;
+    let beyond = rounded - day_span;
+    let (day_delta, nudged_epoch, did_round_beyond_day) = if time_duration_sign(beyond) != -sign {
+        rounded = round_instant_difference(beyond, quantum, mode).ok_or(AddZonedError::OutOfTimeRange)?;
+        (sign, end_epoch + rounded, true)
+    } else {
+        (0, start_epoch + rounded, false)
+    };
+    let mut result = *values;
+    result[3] = (values[3] as i128 + day_delta) as f64;
+    let time_values = plain_time_components_signed(rounded);
+    for index in 0..6 {
+        result[4 + index] = time_values[index] as f64;
+    }
+    Ok((result, nudged_epoch, did_round_beyond_day))
+}
+
+/// DifferenceZonedDateTimeWithTotal（规范 6.5.8）：两个 epoch 的差以 unit 计的总量。
+///
+/// # 步骤
+/// 1. unit 为时间单位 → TotalTimeDuration 快路径（纳秒差直接除单位长度）。
+/// 2. 否则 DifferenceZonedDateTime + TotalRelativeDuration。
+pub(crate) fn difference_zoned_datetime_with_total(
+    ns1: i128, ns2: i128, time_zone: &str, _calendar: &str, unit: usize,
+) -> Result<f64, AddZonedError> {
+    if unit >= 4 {
+        let difference = ns2 - ns1;
+        return Ok(difference as f64 / TIME_UNIT_NS[unit - 4] as f64);
+    }
+    let difference = difference_zoned_datetime(ns1, ns2, time_zone, _calendar, unit)?;
+    let (iso_date, iso_time) = get_iso_date_time_for(time_zone, ns1)?;
+    total_relative_duration(&difference, ns1, ns2, (iso_date, iso_time), time_zone, unit)
+}
+
+/// TotalRelativeDuration（规范 7.5.39）：时长以 unit 计的总量，相对起点折算。
+///
+/// # 步骤
+/// 1. unit 为日历单位或（时区在场且 unit 为 day）→ NudgeToCalendarUnit
+///    （increment = 1、trunc）取 [[Total]]。
+/// 2. 否则 TotalTimeDuration（24h 日折算，zoned 面不可达）。
+fn total_relative_duration(
+    difference: &InternalDuration, origin_ns: i128, dest_ns: i128, iso: ((i128, i128, i128), i128), time_zone: &str,
+    unit: usize,
+) -> Result<f64, AddZonedError> {
+    let values = difference.to_values();
+    // zoned 面时区恒在场：unit ≤ day 恒走日历窗口路径。
+    if unit <= 3 {
+        let sign = if internal_duration_sign(&values) < 0 { -1 } else { 1 };
+        let (iso_date, iso_time) = iso;
+        let epoch_of_date = zoned_epoch_of_date(time_zone, iso_time);
+        let outcome = nudge_to_calendar_unit(
+            sign,
+            &values,
+            origin_ns,
+            dest_ns,
+            iso_date,
+            1,
+            unit,
+            InstantRoundingMode::Trunc,
+            &epoch_of_date,
+        )
+        .map_err(|_| AddZonedError::OutOfDateTimeRange)?;
+        return Ok(outcome.total);
+    }
+    let time_ns = duration_time_only_nanoseconds(&values).ok_or(AddZonedError::OutOfTimeRange)?;
+    let with_days = time_ns
+        .checked_add((values[3] as i128) * DAY_NS)
+        .ok_or(AddZonedError::OutOfTimeRange)?;
+    Ok(with_days as f64 / TIME_UNIT_NS[unit - 4] as f64)
+}
+
 /// ZDT add/subtract 核心：读 receiver 槽后经 add_zoned_datetime 核心叠加 duration。
 ///
 /// # 步骤