diff --git a/crates/oxide_builtins/src/temporal/common.rs b/crates/oxide_builtins/src/temporal/common.rs
index 9bdafca4..2427093c 100644
--- a/crates/oxide_builtins/src/temporal/common.rs
+++ b/crates/oxide_builtins/src/temporal/common.rs
@@ -16,8 +16,8 @@ use oxide_types::object::JsObject;
 use oxide_types::value::JsValue;
 
 use super::{
-    days_in_month, parse_temporal_calendar_string, temporal_calendar_id, valid_iso_date, valid_plain_date_time_range,
-    valid_plain_time,
+    instant_time_zone_offset, parse_iso_date, parse_plain_date_time_string, parse_plain_time_string, valid_iso_date,
+    valid_plain_date_time_range, valid_plain_time,
 };
 
 pub(crate) const MAX_INSTANT_NS: i128 = 8_640_000_000_000_000_000_000;
@@ -549,3 +549,610 @@ pub(crate) fn month_day_bag_calendar_id<H: VmHost>(vm: &mut H, value: JsValue) -
     }
     Err(crate::error::create_type_error(vm, "invalid calendar"))
 }
+
+pub(crate) fn parse_digits(bytes: &[u8], cursor: &mut usize, count: usize) -> Option<i128> {
+    let end = cursor.checked_add(count)?;
+    let digits = bytes.get(*cursor..end)?;
+    if !digits.iter().all(u8::is_ascii_digit) {
+        return None;
+    }
+    *cursor = end;
+    digits
+        .iter()
+        .try_fold(0_i128, |value, digit| value.checked_mul(10)?.checked_add((digit - b'0') as i128))
+}
+
+pub(crate) fn is_leap_year(year: i128) -> bool {
+    year.rem_euclid(4) == 0 && (year.rem_euclid(100) != 0 || year.rem_euclid(400) == 0)
+}
+
+pub(crate) fn days_in_month(year: i128, month: i128) -> Option<i128> {
+    match month {
+        1 | 3 | 5 | 7 | 8 | 10 | 12 => Some(31),
+        4 | 6 | 9 | 11 => Some(30),
+        2 => Some(if is_leap_year(year) { 29 } else { 28 }),
+        _ => None,
+    }
+}
+
+pub(crate) fn days_from_civil(mut year: i128, month: i128, day: i128) -> i128 {
+    year -= i128::from(month <= 2);
+    let era = year.div_euclid(400);
+    let year_of_era = year - era * 400;
+    let shifted_month = month + if month > 2 { -3 } else { 9 };
+    let day_of_year = (153 * shifted_month + 2) / 5 + day - 1;
+    let day_of_era = year_of_era * 365 + year_of_era / 4 - year_of_era / 100 + day_of_year;
+    era * 146_097 + day_of_era - 719_468
+}
+
+pub(crate) enum FractionalSecondDigitsInput {
+    Auto,
+    Number(f64),
+    String(String),
+}
+
+pub(crate) fn parse_fractional_second_digits<H: VmHost>(
+    vm: &mut H, input: FractionalSecondDigitsInput,
+) -> Result<Option<usize>, JsValue> {
+    match input {
+        FractionalSecondDigitsInput::Auto => Ok(None),
+        FractionalSecondDigitsInput::String(value) if value == "auto" => Ok(None),
+        FractionalSecondDigitsInput::String(_) => {
+            Err(crate::error::create_range_error(vm, "invalid fractionalSecondDigits"))
+        }
+        FractionalSecondDigitsInput::Number(value) => {
+            let digits = value.floor();
+            if !digits.is_finite() || !(0.0..=9.0).contains(&digits) {
+                return Err(crate::error::create_range_error(vm, "invalid fractionalSecondDigits"));
+            }
+            Ok(Some(digits as usize))
+        }
+    }
+}
+
+pub(crate) fn parse_offset_minutes(value: &str) -> Option<i32> {
+    let bytes = value.as_bytes();
+    if bytes.len() != 6 || !matches!(bytes[0], b'+' | b'-') || bytes[3] != b':' {
+        return None;
+    }
+    if !bytes[1..3].iter().all(u8::is_ascii_digit) || !bytes[4..6].iter().all(u8::is_ascii_digit) {
+        return None;
+    }
+    let hours = i32::from(bytes[1] - b'0') * 10 + i32::from(bytes[2] - b'0');
+    let minutes = i32::from(bytes[4] - b'0') * 10 + i32::from(bytes[5] - b'0');
+    if hours > 23 || minutes > 59 {
+        return None;
+    }
+    let magnitude = hours * 60 + minutes;
+    Some(if bytes[0] == b'-' { -magnitude } else { magnitude })
+}
+
+pub(crate) fn canonical_time_zone(value: &str) -> Option<(String, i32)> {
+    let input = value.trim();
+    if input.eq_ignore_ascii_case("UTC") || input.eq_ignore_ascii_case("Z") {
+        return Some(("UTC".to_string(), 0));
+    }
+    if let Some(offset) = parse_offset_minutes(input) {
+        return Some((input.to_string(), offset));
+    }
+
+    // ±HH 基本偏移（"+01" / "-05"）：3 字符，hour ≤ 23，分钟恒 0。仅放宽构造器时区接受面。
+    if input.len() == 3
+        && matches!(input.as_bytes()[0], b'+' | b'-')
+        && input.as_bytes()[1..3].iter().all(u8::is_ascii_digit)
+    {
+        let hour = (input.as_bytes()[1] - b'0') as i32 * 10 + (input.as_bytes()[2] - b'0') as i32;
+        if hour <= 23 {
+            let sign = if input.as_bytes()[0] == b'-' { -1 } else { 1 };
+            return Some((input.to_string(), sign * hour * 60));
+        }
+        return None;
+    }
+
+    // ±HHMM 基本偏移（"+0000" / "-0530"）：5 字符，无冒号，分钟位可选非零。4 位无冒号归一形式。
+    if input.len() == 5
+        && matches!(input.as_bytes()[0], b'+' | b'-')
+        && input.as_bytes()[1..5].iter().all(u8::is_ascii_digit)
+    {
+        let hour = (input.as_bytes()[1] - b'0') as i32 * 10 + (input.as_bytes()[2] - b'0') as i32;
+        let minute = (input.as_bytes()[3] - b'0') as i32 * 10 + (input.as_bytes()[4] - b'0') as i32;
+        if hour <= 23 && minute <= 59 {
+            let sign = if input.as_bytes()[0] == b'-' { -1 } else { 1 };
+            return Some((input.to_string(), sign * (hour * 60 + minute)));
+        }
+        return None;
+    }
+    if input.starts_with("-000000") {
+        return None;
+    }
+
+    // 带 annotation 的日期时间以最后一个方括号内标识符为准。
+    if let Some(open) = input.rfind('[') {
+        if !input.ends_with(']') || open + 2 > input.len() {
+            return None;
+        }
+        let annotation = &input[open + 1..input.len() - 1];
+        if annotation.eq_ignore_ascii_case("UTC") {
+            return Some(("UTC".to_string(), 0));
+        }
+        return parse_offset_minutes(annotation).map(|offset| (annotation.to_string(), offset));
+    }
+
+    let time_start = input.find(['T', 't', ' '])?;
+    let time = &input[time_start + 1..];
+    if time.ends_with(['Z', 'z']) {
+        return Some(("UTC".to_string(), 0));
+    }
+    let offset_start = time
+        .char_indices()
+        .rev()
+        .find_map(|(index, ch)| matches!(ch, '+' | '-').then_some(index))?;
+    let offset_id = &time[offset_start..];
+    parse_offset_minutes(offset_id).map(|offset| (offset_id.to_string(), offset))
+}
+
+pub(crate) fn civil_from_days(days: i128) -> (i128, i128, i128) {
+    let shifted = days + 719_468;
+    let era = shifted.div_euclid(146_097);
+    let day_of_era = shifted - era * 146_097;
+    let year_of_era = (day_of_era - day_of_era / 1_460 + day_of_era / 36_524 - day_of_era / 146_096) / 365;
+    let mut year = year_of_era + era * 400;
+    let day_of_year = day_of_era - (365 * year_of_era + year_of_era / 4 - year_of_era / 100);
+    let month_prime = (5 * day_of_year + 2) / 153;
+    let day = day_of_year - (153 * month_prime + 2) / 5 + 1;
+    let month = month_prime + if month_prime < 10 { 3 } else { -9 };
+    year += i128::from(month <= 2);
+    (year, month, day)
+}
+
+pub(crate) fn format_iso_year(year: i128) -> String {
+    if (0..=9_999).contains(&year) {
+        format!("{year:04}")
+    } else if year >= 0 {
+        format!("+{year:06}")
+    } else {
+        format!("-{:06}", -year)
+    }
+}
+
+pub(crate) fn validate_temporal_annotation_suffix(mut suffix: &str) -> Result<(), String> {
+    let mut calendar_seen = false;
+    let mut saw_critical_calendar = false;
+    let mut time_zone_seen = false;
+    while !suffix.is_empty() {
+        if !suffix.starts_with('[') {
+            return Err("invalid annotation suffix".into());
+        }
+        let Some(end) = suffix.find(']') else {
+            return Err("unterminated annotation".into());
+        };
+        if end == 1 {
+            return Err("empty annotation".into());
+        }
+        let annotation = &suffix[1..end];
+        let (critical, body) = annotation.strip_prefix('!').map_or((false, annotation), |body| (true, body));
+        if let Some((key, value)) = body.split_once('=') {
+            if key.bytes().any(|byte| byte.is_ascii_uppercase()) {
+                return Err("annotation keys must be lowercase".into());
+            }
+            if key == "u-ca" {
+                if calendar_seen {
+                    if critical || saw_critical_calendar {
+                        return Err("invalid calendar annotation".into());
+                    }
+                } else if is_builtin_calendar_id(value).is_none() {
+                    return Err("invalid calendar annotation".into());
+                } else {
+                    calendar_seen = true;
+                    saw_critical_calendar = critical;
+                }
+            } else if critical {
+                return Err("unknown critical annotation".into());
+            }
+        } else {
+            if time_zone_seen {
+                return Err("invalid time-zone annotation".into());
+            }
+            time_zone_seen = true;
+        }
+        suffix = &suffix[end + 1..];
+    }
+    Ok(())
+}
+
+/// 剥离 ISO 偏移（±HH、±HHMM、±HH:MM、±HHMMSS、±HH:MM:SS，秒可带小数），返回剩余部分。
+pub(crate) fn strip_iso_offset(input: &str) -> Result<&str, String> {
+    let bytes = input.as_bytes();
+    if bytes.len() < 3 || !matches!(bytes[0], b'+' | b'-') {
+        return Err("invalid ISO offset".into());
+    }
+    let colon = bytes.len() > 3 && bytes[3] == b':';
+    let mut i = 1usize;
+    let take_digits = |count: usize, cursor: &mut usize| -> Result<(), String> {
+        if *cursor + count > bytes.len() || !bytes[*cursor..*cursor + count].iter().all(u8::is_ascii_digit) {
+            return Err("invalid ISO offset".into());
+        }
+        *cursor += count;
+        Ok(())
+    };
+    take_digits(2, &mut i)?;
+    if i < bytes.len() {
+        if colon {
+            if bytes[i] != b':' {
+                return Err("invalid ISO offset".into());
+            }
+            i += 1;
+        }
+        if i + 2 <= bytes.len() && bytes[i..i + 2].iter().all(u8::is_ascii_digit) {
+            i += 2;
+            if i < bytes.len() {
+                if colon {
+                    if bytes[i] != b':' {
+                        return Err("invalid ISO offset".into());
+                    }
+                    i += 1;
+                }
+                if i + 2 <= bytes.len() && bytes[i..i + 2].iter().all(u8::is_ascii_digit) {
+                    i += 2;
+                    if i < bytes.len() && matches!(bytes[i], b'.' | b',') {
+                        i += 1;
+                        let start = i;
+                        while i < bytes.len() && bytes[i].is_ascii_digit() {
+                            i += 1;
+                        }
+                        if i == start {
+                            return Err("invalid ISO offset fraction".into());
+                        }
+                        if i - start > 9 {
+                            return Err("invalid ISO offset fraction".into());
+                        }
+                    }
+                }
+            }
+        }
+    }
+    let digits: String = input[1..i].chars().filter(|ch| ch.is_ascii_digit()).take(6).collect();
+    if digits.len() < 2 {
+        return Err("invalid ISO offset".into());
+    }
+    let hour: u32 = digits[..2].parse().map_err(|_| "invalid ISO offset".to_string())?;
+    let minute: u32 = if digits.len() >= 4 {
+        digits[2..4].parse().map_err(|_| "invalid ISO offset".to_string())?
+    } else {
+        0
+    };
+    let second: u32 = if digits.len() >= 6 {
+        digits[4..6].parse().map_err(|_| "invalid ISO offset".to_string())?
+    } else {
+        0
+    };
+    if hour > 23 || minute > 59 || second > 59 {
+        return Err("invalid ISO offset".into());
+    }
+    Ok(&input[i..])
+}
+
+/// ParseTemporalDateString：PlainDate 字符串（时间部分可选且被忽略，仅按日期做范围校验）。
+pub(crate) fn parse_plain_date_string(input: &str) -> Result<(i32, u32, u32), String> {
+    parse_temporal_string_impl(input, false).map(|(year, month, day, _)| (year, month, day))
+}
+
+pub(crate) fn parse_temporal_string_impl(
+    input: &str, enforce_date_time_range: bool,
+) -> Result<(i32, u32, u32, f64), String> {
+    let trimmed = input.trim();
+    if trimmed.contains('\u{2212}') {
+        return Err("variant minus sign is not valid for PlainDateTime".into());
+    }
+    let text = trimmed.to_owned();
+    let annotation_start = text.find('[').unwrap_or(text.len());
+    validate_temporal_annotation_suffix(&text[annotation_start..])?;
+    let text = &text[..annotation_start];
+    if text.contains('Z') || text.contains('z') {
+        return Err("UTC designator is not valid for PlainDateTime".into());
+    }
+    let separator = text.find(['T', 't', ' ']);
+    let date_part = match separator {
+        Some(index) => &text[..index],
+        None => text,
+    };
+    let (year, month, day) = parse_iso_date(date_part)?;
+    let Some(separator) = separator else {
+        if !valid_iso_date(year, month, day)
+            || (enforce_date_time_range && !valid_plain_date_time_range(year, month, day, 0.0))
+        {
+            return Err("invalid ISO date".into());
+        }
+        return Ok((year, month, day, 0.0));
+    };
+
+    let time_and_suffix = &text[separator + 1..];
+    let time_end = time_and_suffix
+        .char_indices()
+        .find_map(|(index, ch)| matches!(ch, '+' | '-').then_some(index))
+        .unwrap_or(time_and_suffix.len());
+    if time_end < time_and_suffix.len() && !strip_iso_offset(&time_and_suffix[time_end..])?.is_empty() {
+        return Err("invalid ISO offset".into());
+    }
+    let time = &time_and_suffix[..time_end];
+    if time.is_empty() {
+        return Err("missing ISO time".into());
+    }
+
+    let (clock, fraction) = match time.find(['.', ',']) {
+        Some(index) => (&time[..index], Some(&time[index + 1..])),
+        None => (time, None),
+    };
+    let fields = if clock.contains(':') {
+        clock.split(':').collect::<Vec<_>>()
+    } else {
+        if clock.len() % 2 != 0 || clock.len() > 6 {
+            return Err("invalid ISO time".into());
+        }
+        clock
+            .as_bytes()
+            .chunks(2)
+            .map(std::str::from_utf8)
+            .collect::<Result<Vec<_>, _>>()
+            .map_err(|_| "invalid ISO time".to_string())?
+    };
+    if fields.is_empty() || fields.len() > 3 || fields.iter().any(|field| field.len() != 2) {
+        return Err("invalid ISO time".into());
+    }
+    if fraction.is_some() && fields.len() < 3 {
+        return Err("fractional hours and minutes are not valid".into());
+    }
+    let parse_field = |index: usize| -> Result<u32, String> {
+        fields
+            .get(index)
+            .map_or(Ok(0), |field| field.parse().map_err(|_| "invalid ISO time".to_string()))
+    };
+    let hour = parse_field(0)?;
+    let minute = parse_field(1)?;
+    let mut second = parse_field(2)?;
+    if second == 60 {
+        second = 59;
+    }
+    let subsecond = match fraction {
+        Some(digits) if !digits.is_empty() && digits.len() <= 9 && digits.bytes().all(|byte| byte.is_ascii_digit()) => {
+            let mut padded = digits.to_owned();
+            padded.extend(std::iter::repeat('0').take(9 - digits.len()));
+            padded.parse::<u32>().map_err(|_| "invalid ISO fraction".to_string())?
+        }
+        Some(_) => return Err("invalid ISO fraction".into()),
+        None => 0,
+    };
+    let millisecond = subsecond / 1_000_000;
+    let microsecond = subsecond / 1_000 % 1_000;
+    let nanosecond = subsecond % 1_000;
+    if !valid_plain_time(hour, minute, second, millisecond, microsecond, nanosecond) {
+        return Err("invalid ISO time".into());
+    }
+    let total_ns = hour as f64 * 3_600_000_000_000.0
+        + minute as f64 * 60_000_000_000.0
+        + second as f64 * 1_000_000_000.0
+        + subsecond as f64;
+    if !valid_iso_date(year, month, day)
+        || (enforce_date_time_range && !valid_plain_date_time_range(year, month, day, total_ns))
+    {
+        return Err("invalid ISO date".into());
+    }
+    Ok((year, month, day, total_ns))
+}
+
+/// 规范 BuiltinCalendarID 全集（18 项）。匹配用 eq_ignore_ascii_case（ASCII 折叠，
+/// 禁 to_lowercase：U+0130 点 I 会被 Unicode 折叠成 i+组合符，误判为 iso8601）。
+pub(crate) const CALENDAR_ID_WHITELIST: [&str; 18] = [
+    "buddhist",
+    "chinese",
+    "coptic",
+    "dangi",
+    "ethioaa",
+    "ethiopic",
+    "gregory",
+    "hebrew",
+    "indian",
+    "islamic",
+    "islamic-civil",
+    "islamic-rcy",
+    "islamic-tbla",
+    "islamic-umalqura",
+    "iso8601",
+    "japanese",
+    "persian",
+    "roc",
+];
+
+/// 严格白名单匹配：命中返回规范小写形式，未命中返回 None。
+pub(crate) fn is_builtin_calendar_id(value: &str) -> Option<&'static str> {
+    CALENDAR_ID_WHITELIST.iter().find(|id| value.eq_ignore_ascii_case(id)).copied()
+}
+
+/// 严格日历 ID 解析：只走 18 项白名单，拒绝 ISO 串（含注解/compact/extended/空串）。
+/// 供构造器日历参数与注解值判定使用。
+pub(crate) fn parse_temporal_calendar_id_strict(input: &str) -> Result<String, String> {
+    let trimmed = input.trim();
+    is_builtin_calendar_id(trimmed)
+        .map(str::to_string)
+        .ok_or_else(|| "invalid calendar".to_string())
+}
+
+/// ParseTemporalCalendarString：日历标识符 = 18 项内置日历 ID（ASCII 大小写不敏感）
+/// 或合法 ISO 日期(-时间)字符串（含部分日期 YYYY-MM / MM-DD，可选时间、偏移、注解）。
+/// 返回规范化日历 ID：白名单命中返回规范小写，ISO 串路径恒为 "iso8601"。
+pub(crate) fn parse_temporal_calendar_string(input: &str) -> Result<String, String> {
+    let trimmed = input.trim();
+    if trimmed.is_empty() {
+        return Err("invalid calendar".into());
+    }
+    if let Some(id) = is_builtin_calendar_id(trimmed) {
+        return Ok(id.to_string());
+    }
+    if trimmed.contains('\u{2212}') {
+        return Err("variant minus sign is not valid for calendar".into());
+    }
+    // 完整日期时间字符串（含注解校验），例如 2020-01-01T00:00:00.000000000[u-ca=iso8601]
+    if parse_plain_date_time_string(trimmed).is_ok() {
+        return Ok("iso8601".to_string());
+    }
+    // 纯时间字符串（TemporalTimeString），例如 "15:23" / "T0030" / "152330.1-08"。
+    if parse_plain_time_string(trimmed).is_some() {
+        return Ok("iso8601".to_string());
+    }
+    // 部分日期：YYYY-MM 或 MM-DD（可带注解）
+    let text = trimmed.to_owned();
+    let annotation_start = text.find('[').unwrap_or(text.len());
+    validate_temporal_annotation_suffix(&text[annotation_start..])?;
+    let text = &text[..annotation_start];
+    if text.contains(['Z', 'z']) {
+        return Err("UTC designator is not valid for calendar".into());
+    }
+    parse_partial_calendar_date(text)?;
+    Ok("iso8601".to_string())
+}
+
+/// 部分 ISO 日期（无时间）：YYYY[-MM[-DD]] 或 MM-DD；校验月份/日期基本范围并拒绝负零年。
+pub(crate) fn parse_partial_calendar_date(input: &str) -> Result<(), String> {
+    let bytes = input.as_bytes();
+    let mut i = 0usize;
+    let signed = i < bytes.len() && matches!(bytes[i], b'+' | b'-');
+    let negative = signed && bytes[i] == b'-';
+    if signed {
+        i += 1;
+    }
+    let start = i;
+    while i < bytes.len() && bytes[i].is_ascii_digit() {
+        i += 1;
+    }
+    let digits = &input[start..i];
+    let rest = &input[i..];
+    if digits.is_empty() {
+        return Err("invalid calendar date".into());
+    }
+    // MM-DD 形式（无年份）
+    if digits.len() == 2 {
+        if !rest.starts_with('-') {
+            return Err("invalid calendar date".into());
+        }
+        let day_part = &rest[1..];
+        if day_part.len() != 2 || !day_part.bytes().all(|byte| byte.is_ascii_digit()) {
+            return Err("invalid calendar day".into());
+        }
+        let month: u32 = digits.parse().map_err(|_| "invalid calendar month".to_string())?;
+        let day: u32 = day_part.parse().map_err(|_| "invalid calendar day".to_string())?;
+        if month == 0 || month > 12 || day == 0 || day > 31 {
+            return Err("invalid calendar date".into());
+        }
+        return Ok(());
+    }
+    if !(4..=6).contains(&digits.len()) {
+        return Err("invalid calendar year".into());
+    }
+    if negative && digits.bytes().all(|byte| byte == b'0') {
+        return Err("invalid calendar negative zero year".into());
+    }
+    let mut rest2 = rest;
+    let mut month: Option<u32> = None;
+    let mut day: Option<u32> = None;
+    if rest2.starts_with('-') {
+        rest2 = &rest2[1..];
+        if rest2.len() < 2 || !rest2.as_bytes()[..2].iter().all(u8::is_ascii_digit) {
+            return Err("invalid calendar month".into());
+        }
+        month = Some(rest2[..2].parse().map_err(|_| "invalid calendar month".to_string())?);
+        rest2 = &rest2[2..];
+        if rest2.starts_with('-') {
+            rest2 = &rest2[1..];
+            if rest2.len() != 2 || !rest2.bytes().all(|byte| byte.is_ascii_digit()) {
+                return Err("invalid calendar day".into());
+            }
+            day = Some(rest2.parse().map_err(|_| "invalid calendar day".to_string())?);
+            rest2 = "";
+        }
+    }
+    if !rest2.is_empty() {
+        return Err("invalid trailing calendar content".into());
+    }
+    if month.is_some_and(|m| m == 0 || m > 12) || day.is_some_and(|d| d == 0 || d > 31) {
+        return Err("invalid calendar date".into());
+    }
+    Ok(())
+}
+
+/// ToTemporalCalendar（宽松版，property bag 路径用）：undefined → None；
+/// string → 宽松解析（白名单 ID 或 ISO 串）；Temporal 实例 → 读日历槽（不触发属性 getter）；
+/// 其他类型 → TypeError。
+pub(crate) fn temporal_calendar_id<H: VmHost>(vm: &mut H, value: JsValue) -> Result<Option<String>, JsValue> {
+    if value.is_undefined() {
+        return Ok(None);
+    }
+    if value.is_string() {
+        return parse_temporal_calendar_string(&to_string(value))
+            .map(Some)
+            .map_err(|_| crate::error::create_range_error(vm, "invalid calendar"));
+    }
+    if value.is_object() {
+        let ptr = value.as_js_object_ptr();
+        if !ptr.is_null() {
+            let obj = unsafe { &*ptr };
+            if obj.is_plain_date_obj() {
+                return Ok(Some(get_calendar_id(obj, 3)));
+            }
+            if obj.is_plain_date_time_obj() {
+                return Ok(Some(get_calendar_id(obj, 4)));
+            }
+            if obj.is_zoned_date_time_obj() {
+                return Ok(Some(get_calendar_id(obj, 2)));
+            }
+            if obj.is_plain_month_day_obj() || obj.is_plain_year_month_obj() {
+                return Ok(Some(get_calendar_id(obj, 3)));
+            }
+        }
+    }
+    Err(crate::error::create_type_error(vm, "invalid calendar"))
+}
+
+/// ToTemporalCalendar 严格版（构造器日历参数用）：字符串只走 18 项白名单，拒绝 ISO 串；
+/// undefined / 其他分支与宽松版一致。
+pub(crate) fn temporal_calendar_id_strict<H: VmHost>(vm: &mut H, value: JsValue) -> Result<Option<String>, JsValue> {
+    if value.is_string() {
+        return parse_temporal_calendar_id_strict(&to_string(value))
+            .map(Some)
+            .map_err(|_| crate::error::create_range_error(vm, "invalid calendar"));
+    }
+    temporal_calendar_id(vm, value)
+}
+
+/// 将 ZonedDateTime 按时区偏移转换为本地 PlainDateTime 分量。
+pub(crate) fn zoned_date_time_plain_parts<H: VmHost>(
+    vm: &mut H, obj: &JsObject,
+) -> Result<(i32, u32, u32, f64), JsValue> {
+    let Some(epoch_ns) = get_instant_epoch_ns(obj) else {
+        return Err(crate::error::create_range_error(vm, "invalid ZonedDateTime"));
+    };
+    let time_zone_id = to_string(obj.get_prop_at(1));
+    let Some(offset_minutes) = instant_time_zone_offset(&time_zone_id) else {
+        return Err(crate::error::create_range_error(vm, "invalid time zone"));
+    };
+    const DAY_NS: i128 = 86_400_000_000_000;
+    let local_ns = epoch_ns + i128::from(offset_minutes) * 60_000_000_000;
+    let days = local_ns.div_euclid(DAY_NS);
+    let time_ns = local_ns.rem_euclid(DAY_NS) as f64;
+    let (year, month, day) = civil_from_days(days);
+    if !valid_plain_date_time_range(year as i32, month as u32, day as u32, time_ns) {
+        return Err(crate::error::create_range_error(vm, "invalid date-time"));
+    }
+    Ok((year as i32, month as u32, day as u32, time_ns))
+}
+
+/// 本地墙钟分量 + 时区偏移（分钟）→ 纪元纳秒（zoned_date_time_plain_parts 的逆）。
+///
+/// # 边界与前提
+/// - (year, month, day, time_ns) 须已通过 valid_iso_date / valid_plain_time 校验（调用方保证）。
+/// - 仅做 checked 溢出防护，Instant 范围校验由调用方按需执行。
+pub(crate) fn local_to_epoch_ns(year: i32, month: u32, day: u32, time_ns: f64, offset_minutes: i32) -> Option<i128> {
+    let days = days_from_civil(i128::from(year), i128::from(month), i128::from(day));
+    days.checked_mul(86_400_000_000_000)?
+        .checked_add(time_ns as i128)?
+        .checked_sub(i128::from(offset_minutes) * 60_000_000_000)
+}
diff --git a/crates/oxide_builtins/src/temporal/mod.rs b/crates/oxide_builtins/src/temporal/mod.rs
index 2dc766f7..778baae7 100644
--- a/crates/oxide_builtins/src/temporal/mod.rs
+++ b/crates/oxide_builtins/src/temporal/mod.rs
@@ -10,41 +10,6 @@ mod common;
 
 use common::*;
 
-fn parse_digits(bytes: &[u8], cursor: &mut usize, count: usize) -> Option<i128> {
-    let end = cursor.checked_add(count)?;
-    let digits = bytes.get(*cursor..end)?;
-    if !digits.iter().all(u8::is_ascii_digit) {
-        return None;
-    }
-    *cursor = end;
-    digits
-        .iter()
-        .try_fold(0_i128, |value, digit| value.checked_mul(10)?.checked_add((digit - b'0') as i128))
-}
-
-fn is_leap_year(year: i128) -> bool {
-    year.rem_euclid(4) == 0 && (year.rem_euclid(100) != 0 || year.rem_euclid(400) == 0)
-}
-
-fn days_in_month(year: i128, month: i128) -> Option<i128> {
-    match month {
-        1 | 3 | 5 | 7 | 8 | 10 | 12 => Some(31),
-        4 | 6 | 9 | 11 => Some(30),
-        2 => Some(if is_leap_year(year) { 29 } else { 28 }),
-        _ => None,
-    }
-}
-
-fn days_from_civil(mut year: i128, month: i128, day: i128) -> i128 {
-    year -= i128::from(month <= 2);
-    let era = year.div_euclid(400);
-    let year_of_era = year - era * 400;
-    let shifted_month = month + if month > 2 { -3 } else { 9 };
-    let day_of_year = (153 * shifted_month + 2) / 5 + day - 1;
-    let day_of_era = year_of_era * 365 + year_of_era / 4 - year_of_era / 100 + day_of_year;
-    era * 146_097 + day_of_era - 719_468
-}
-
 fn instant_string_without_annotations(input: &str) -> Option<&str> {
     let Some(first_annotation) = input.find('[') else {
         return Some(input);
@@ -796,140 +761,10 @@ pub fn instant_since<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
     instant_difference(vm, args, true)
 }
 
-enum FractionalSecondDigitsInput {
-    Auto,
-    Number(f64),
-    String(String),
-}
-
-fn parse_fractional_second_digits<H: VmHost>(
-    vm: &mut H, input: FractionalSecondDigitsInput,
-) -> Result<Option<usize>, JsValue> {
-    match input {
-        FractionalSecondDigitsInput::Auto => Ok(None),
-        FractionalSecondDigitsInput::String(value) if value == "auto" => Ok(None),
-        FractionalSecondDigitsInput::String(_) => {
-            Err(crate::error::create_range_error(vm, "invalid fractionalSecondDigits"))
-        }
-        FractionalSecondDigitsInput::Number(value) => {
-            let digits = value.floor();
-            if !digits.is_finite() || !(0.0..=9.0).contains(&digits) {
-                return Err(crate::error::create_range_error(vm, "invalid fractionalSecondDigits"));
-            }
-            Ok(Some(digits as usize))
-        }
-    }
-}
-
-fn parse_offset_minutes(value: &str) -> Option<i32> {
-    let bytes = value.as_bytes();
-    if bytes.len() != 6 || !matches!(bytes[0], b'+' | b'-') || bytes[3] != b':' {
-        return None;
-    }
-    if !bytes[1..3].iter().all(u8::is_ascii_digit) || !bytes[4..6].iter().all(u8::is_ascii_digit) {
-        return None;
-    }
-    let hours = i32::from(bytes[1] - b'0') * 10 + i32::from(bytes[2] - b'0');
-    let minutes = i32::from(bytes[4] - b'0') * 10 + i32::from(bytes[5] - b'0');
-    if hours > 23 || minutes > 59 {
-        return None;
-    }
-    let magnitude = hours * 60 + minutes;
-    Some(if bytes[0] == b'-' { -magnitude } else { magnitude })
-}
-
-fn canonical_time_zone(value: &str) -> Option<(String, i32)> {
-    let input = value.trim();
-    if input.eq_ignore_ascii_case("UTC") || input.eq_ignore_ascii_case("Z") {
-        return Some(("UTC".to_string(), 0));
-    }
-    if let Some(offset) = parse_offset_minutes(input) {
-        return Some((input.to_string(), offset));
-    }
-
-    // ±HH 基本偏移（"+01" / "-05"）：3 字符，hour ≤ 23，分钟恒 0。仅放宽构造器时区接受面。
-    if input.len() == 3
-        && matches!(input.as_bytes()[0], b'+' | b'-')
-        && input.as_bytes()[1..3].iter().all(u8::is_ascii_digit)
-    {
-        let hour = (input.as_bytes()[1] - b'0') as i32 * 10 + (input.as_bytes()[2] - b'0') as i32;
-        if hour <= 23 {
-            let sign = if input.as_bytes()[0] == b'-' { -1 } else { 1 };
-            return Some((input.to_string(), sign * hour * 60));
-        }
-        return None;
-    }
-
-    // ±HHMM 基本偏移（"+0000" / "-0530"）：5 字符，无冒号，分钟位可选非零。4 位无冒号归一形式。
-    if input.len() == 5
-        && matches!(input.as_bytes()[0], b'+' | b'-')
-        && input.as_bytes()[1..5].iter().all(u8::is_ascii_digit)
-    {
-        let hour = (input.as_bytes()[1] - b'0') as i32 * 10 + (input.as_bytes()[2] - b'0') as i32;
-        let minute = (input.as_bytes()[3] - b'0') as i32 * 10 + (input.as_bytes()[4] - b'0') as i32;
-        if hour <= 23 && minute <= 59 {
-            let sign = if input.as_bytes()[0] == b'-' { -1 } else { 1 };
-            return Some((input.to_string(), sign * (hour * 60 + minute)));
-        }
-        return None;
-    }
-    if input.starts_with("-000000") {
-        return None;
-    }
-
-    // 带 annotation 的日期时间以最后一个方括号内标识符为准。
-    if let Some(open) = input.rfind('[') {
-        if !input.ends_with(']') || open + 2 > input.len() {
-            return None;
-        }
-        let annotation = &input[open + 1..input.len() - 1];
-        if annotation.eq_ignore_ascii_case("UTC") {
-            return Some(("UTC".to_string(), 0));
-        }
-        return parse_offset_minutes(annotation).map(|offset| (annotation.to_string(), offset));
-    }
-
-    let time_start = input.find(['T', 't', ' '])?;
-    let time = &input[time_start + 1..];
-    if time.ends_with(['Z', 'z']) {
-        return Some(("UTC".to_string(), 0));
-    }
-    let offset_start = time
-        .char_indices()
-        .rev()
-        .find_map(|(index, ch)| matches!(ch, '+' | '-').then_some(index))?;
-    let offset_id = &time[offset_start..];
-    parse_offset_minutes(offset_id).map(|offset| (offset_id.to_string(), offset))
-}
-
 fn instant_time_zone_offset(value: &str) -> Option<i32> {
     canonical_time_zone(value).map(|(_, offset)| offset)
 }
 
-fn civil_from_days(days: i128) -> (i128, i128, i128) {
-    let shifted = days + 719_468;
-    let era = shifted.div_euclid(146_097);
-    let day_of_era = shifted - era * 146_097;
-    let year_of_era = (day_of_era - day_of_era / 1_460 + day_of_era / 36_524 - day_of_era / 146_096) / 365;
-    let mut year = year_of_era + era * 400;
-    let day_of_year = day_of_era - (365 * year_of_era + year_of_era / 4 - year_of_era / 100);
-    let month_prime = (5 * day_of_year + 2) / 153;
-    let day = day_of_year - (153 * month_prime + 2) / 5 + 1;
-    let month = month_prime + if month_prime < 10 { 3 } else { -9 };
-    year += i128::from(month <= 2);
-    (year, month, day)
-}
-
-fn format_iso_year(year: i128) -> String {
-    if (0..=9_999).contains(&year) {
-        format!("{year:04}")
-    } else if year >= 0 {
-        format!("+{year:06}")
-    } else {
-        format!("-{:06}", -year)
-    }
-}
-
 fn format_instant_iso(
     epoch_ns: i128, offset_minutes: Option<i32>, include_seconds: bool, fractional_digits: Option<usize>,
 ) -> Option<String> {
@@ -5057,436 +4892,10 @@ pub fn plain_date_time_constructor<H: VmHost>(vm: &mut H, args: &[u8]) -> Native
     )
 }
 
-fn validate_temporal_annotation_suffix(mut suffix: &str) -> Result<(), String> {
-    let mut calendar_seen = false;
-    let mut saw_critical_calendar = false;
-    let mut time_zone_seen = false;
-    while !suffix.is_empty() {
-        if !suffix.starts_with('[') {
-            return Err("invalid annotation suffix".into());
-        }
-        let Some(end) = suffix.find(']') else {
-            return Err("unterminated annotation".into());
-        };
-        if end == 1 {
-            return Err("empty annotation".into());
-        }
-        let annotation = &suffix[1..end];
-        let (critical, body) = annotation.strip_prefix('!').map_or((false, annotation), |body| (true, body));
-        if let Some((key, value)) = body.split_once('=') {
-            if key.bytes().any(|byte| byte.is_ascii_uppercase()) {
-                return Err("annotation keys must be lowercase".into());
-            }
-            if key == "u-ca" {
-                if calendar_seen {
-                    if critical || saw_critical_calendar {
-                        return Err("invalid calendar annotation".into());
-                    }
-                } else if is_builtin_calendar_id(value).is_none() {
-                    return Err("invalid calendar annotation".into());
-                } else {
-                    calendar_seen = true;
-                    saw_critical_calendar = critical;
-                }
-            } else if critical {
-                return Err("unknown critical annotation".into());
-            }
-        } else {
-            if time_zone_seen {
-                return Err("invalid time-zone annotation".into());
-            }
-            time_zone_seen = true;
-        }
-        suffix = &suffix[end + 1..];
-    }
-    Ok(())
-}
-
-/// 剥离 ISO 偏移（±HH、±HHMM、±HH:MM、±HHMMSS、±HH:MM:SS，秒可带小数），返回剩余部分。
-fn strip_iso_offset(input: &str) -> Result<&str, String> {
-    let bytes = input.as_bytes();
-    if bytes.len() < 3 || !matches!(bytes[0], b'+' | b'-') {
-        return Err("invalid ISO offset".into());
-    }
-    let colon = bytes.len() > 3 && bytes[3] == b':';
-    let mut i = 1usize;
-    let take_digits = |count: usize, cursor: &mut usize| -> Result<(), String> {
-        if *cursor + count > bytes.len() || !bytes[*cursor..*cursor + count].iter().all(u8::is_ascii_digit) {
-            return Err("invalid ISO offset".into());
-        }
-        *cursor += count;
-        Ok(())
-    };
-    take_digits(2, &mut i)?;
-    if i < bytes.len() {
-        if colon {
-            if bytes[i] != b':' {
-                return Err("invalid ISO offset".into());
-            }
-            i += 1;
-        }
-        if i + 2 <= bytes.len() && bytes[i..i + 2].iter().all(u8::is_ascii_digit) {
-            i += 2;
-            if i < bytes.len() {
-                if colon {
-                    if bytes[i] != b':' {
-                        return Err("invalid ISO offset".into());
-                    }
-                    i += 1;
-                }
-                if i + 2 <= bytes.len() && bytes[i..i + 2].iter().all(u8::is_ascii_digit) {
-                    i += 2;
-                    if i < bytes.len() && matches!(bytes[i], b'.' | b',') {
-                        i += 1;
-                        let start = i;
-                        while i < bytes.len() && bytes[i].is_ascii_digit() {
-                            i += 1;
-                        }
-                        if i == start {
-                            return Err("invalid ISO offset fraction".into());
-                        }
-                        if i - start > 9 {
-                            return Err("invalid ISO offset fraction".into());
-                        }
-                    }
-                }
-            }
-        }
-    }
-    let digits: String = input[1..i].chars().filter(|ch| ch.is_ascii_digit()).take(6).collect();
-    if digits.len() < 2 {
-        return Err("invalid ISO offset".into());
-    }
-    let hour: u32 = digits[..2].parse().map_err(|_| "invalid ISO offset".to_string())?;
-    let minute: u32 = if digits.len() >= 4 {
-        digits[2..4].parse().map_err(|_| "invalid ISO offset".to_string())?
-    } else {
-        0
-    };
-    let second: u32 = if digits.len() >= 6 {
-        digits[4..6].parse().map_err(|_| "invalid ISO offset".to_string())?
-    } else {
-        0
-    };
-    if hour > 23 || minute > 59 || second > 59 {
-        return Err("invalid ISO offset".into());
-    }
-    Ok(&input[i..])
-}
-
 fn parse_plain_date_time_string(input: &str) -> Result<(i32, u32, u32, f64), String> {
     parse_temporal_string_impl(input, true)
 }
 
-/// ParseTemporalDateString：PlainDate 字符串（时间部分可选且被忽略，仅按日期做范围校验）。
-fn parse_plain_date_string(input: &str) -> Result<(i32, u32, u32), String> {
-    parse_temporal_string_impl(input, false).map(|(year, month, day, _)| (year, month, day))
-}
-
-fn parse_temporal_string_impl(input: &str, enforce_date_time_range: bool) -> Result<(i32, u32, u32, f64), String> {
-    let trimmed = input.trim();
-    if trimmed.contains('\u{2212}') {
-        return Err("variant minus sign is not valid for PlainDateTime".into());
-    }
-    let text = trimmed.to_owned();
-    let annotation_start = text.find('[').unwrap_or(text.len());
-    validate_temporal_annotation_suffix(&text[annotation_start..])?;
-    let text = &text[..annotation_start];
-    if text.contains('Z') || text.contains('z') {
-        return Err("UTC designator is not valid for PlainDateTime".into());
-    }
-    let separator = text.find(['T', 't', ' ']);
-    let date_part = match separator {
-        Some(index) => &text[..index],
-        None => text,
-    };
-    let (year, month, day) = parse_iso_date(date_part)?;
-    let Some(separator) = separator else {
-        if !valid_iso_date(year, month, day)
-            || (enforce_date_time_range && !valid_plain_date_time_range(year, month, day, 0.0))
-        {
-            return Err("invalid ISO date".into());
-        }
-        return Ok((year, month, day, 0.0));
-    };
-
-    let time_and_suffix = &text[separator + 1..];
-    let time_end = time_and_suffix
-        .char_indices()
-        .find_map(|(index, ch)| matches!(ch, '+' | '-').then_some(index))
-        .unwrap_or(time_and_suffix.len());
-    if time_end < time_and_suffix.len() && !strip_iso_offset(&time_and_suffix[time_end..])?.is_empty() {
-        return Err("invalid ISO offset".into());
-    }
-    let time = &time_and_suffix[..time_end];
-    if time.is_empty() {
-        return Err("missing ISO time".into());
-    }
-
-    let (clock, fraction) = match time.find(['.', ',']) {
-        Some(index) => (&time[..index], Some(&time[index + 1..])),
-        None => (time, None),
-    };
-    let fields = if clock.contains(':') {
-        clock.split(':').collect::<Vec<_>>()
-    } else {
-        if clock.len() % 2 != 0 || clock.len() > 6 {
-            return Err("invalid ISO time".into());
-        }
-        clock
-            .as_bytes()
-            .chunks(2)
-            .map(std::str::from_utf8)
-            .collect::<Result<Vec<_>, _>>()
-            .map_err(|_| "invalid ISO time".to_string())?
-    };
-    if fields.is_empty() || fields.len() > 3 || fields.iter().any(|field| field.len() != 2) {
-        return Err("invalid ISO time".into());
-    }
-    if fraction.is_some() && fields.len() < 3 {
-        return Err("fractional hours and minutes are not valid".into());
-    }
-    let parse_field = |index: usize| -> Result<u32, String> {
-        fields
-            .get(index)
-            .map_or(Ok(0), |field| field.parse().map_err(|_| "invalid ISO time".to_string()))
-    };
-    let hour = parse_field(0)?;
-    let minute = parse_field(1)?;
-    let mut second = parse_field(2)?;
-    if second == 60 {
-        second = 59;
-    }
-    let subsecond = match fraction {
-        Some(digits) if !digits.is_empty() && digits.len() <= 9 && digits.bytes().all(|byte| byte.is_ascii_digit()) => {
-            let mut padded = digits.to_owned();
-            padded.extend(std::iter::repeat('0').take(9 - digits.len()));
-            padded.parse::<u32>().map_err(|_| "invalid ISO fraction".to_string())?
-        }
-        Some(_) => return Err("invalid ISO fraction".into()),
-        None => 0,
-    };
-    let millisecond = subsecond / 1_000_000;
-    let microsecond = subsecond / 1_000 % 1_000;
-    let nanosecond = subsecond % 1_000;
-    if !valid_plain_time(hour, minute, second, millisecond, microsecond, nanosecond) {
-        return Err("invalid ISO time".into());
-    }
-    let total_ns = hour as f64 * 3_600_000_000_000.0
-        + minute as f64 * 60_000_000_000.0
-        + second as f64 * 1_000_000_000.0
-        + subsecond as f64;
-    if !valid_iso_date(year, month, day)
-        || (enforce_date_time_range && !valid_plain_date_time_range(year, month, day, total_ns))
-    {
-        return Err("invalid ISO date".into());
-    }
-    Ok((year, month, day, total_ns))
-}
-
-/// 规范 BuiltinCalendarID 全集（18 项）。匹配用 eq_ignore_ascii_case（ASCII 折叠，
-/// 禁 to_lowercase：U+0130 点 I 会被 Unicode 折叠成 i+组合符，误判为 iso8601）。
-const CALENDAR_ID_WHITELIST: [&str; 18] = [
-    "buddhist",
-    "chinese",
-    "coptic",
-    "dangi",
-    "ethioaa",
-    "ethiopic",
-    "gregory",
-    "hebrew",
-    "indian",
-    "islamic",
-    "islamic-civil",
-    "islamic-rcy",
-    "islamic-tbla",
-    "islamic-umalqura",
-    "iso8601",
-    "japanese",
-    "persian",
-    "roc",
-];
-
-/// 严格白名单匹配：命中返回规范小写形式，未命中返回 None。
-fn is_builtin_calendar_id(value: &str) -> Option<&'static str> {
-    CALENDAR_ID_WHITELIST.iter().find(|id| value.eq_ignore_ascii_case(id)).copied()
-}
-
-/// 严格日历 ID 解析：只走 18 项白名单，拒绝 ISO 串（含注解/compact/extended/空串）。
-/// 供构造器日历参数与注解值判定使用。
-fn parse_temporal_calendar_id_strict(input: &str) -> Result<String, String> {
-    let trimmed = input.trim();
-    is_builtin_calendar_id(trimmed)
-        .map(str::to_string)
-        .ok_or_else(|| "invalid calendar".to_string())
-}
-
-/// ParseTemporalCalendarString：日历标识符 = 18 项内置日历 ID（ASCII 大小写不敏感）
-/// 或合法 ISO 日期(-时间)字符串（含部分日期 YYYY-MM / MM-DD，可选时间、偏移、注解）。
-/// 返回规范化日历 ID：白名单命中返回规范小写，ISO 串路径恒为 "iso8601"。
-fn parse_temporal_calendar_string(input: &str) -> Result<String, String> {
-    let trimmed = input.trim();
-    if trimmed.is_empty() {
-        return Err("invalid calendar".into());
-    }
-    if let Some(id) = is_builtin_calendar_id(trimmed) {
-        return Ok(id.to_string());
-    }
-    if trimmed.contains('\u{2212}') {
-        return Err("variant minus sign is not valid for calendar".into());
-    }
-    // 完整日期时间字符串（含注解校验），例如 2020-01-01T00:00:00.000000000[u-ca=iso8601]
-    if parse_plain_date_time_string(trimmed).is_ok() {
-        return Ok("iso8601".to_string());
-    }
-    // 纯时间字符串（TemporalTimeString），例如 "15:23" / "T0030" / "152330.1-08"。
-    if parse_plain_time_string(trimmed).is_some() {
-        return Ok("iso8601".to_string());
-    }
-    // 部分日期：YYYY-MM 或 MM-DD（可带注解）
-    let text = trimmed.to_owned();
-    let annotation_start = text.find('[').unwrap_or(text.len());
-    validate_temporal_annotation_suffix(&text[annotation_start..])?;
-    let text = &text[..annotation_start];
-    if text.contains(['Z', 'z']) {
-        return Err("UTC designator is not valid for calendar".into());
-    }
-    parse_partial_calendar_date(text)?;
-    Ok("iso8601".to_string())
-}
-
-/// 部分 ISO 日期（无时间）：YYYY[-MM[-DD]] 或 MM-DD；校验月份/日期基本范围并拒绝负零年。
-fn parse_partial_calendar_date(input: &str) -> Result<(), String> {
-    let bytes = input.as_bytes();
-    let mut i = 0usize;
-    let signed = i < bytes.len() && matches!(bytes[i], b'+' | b'-');
-    let negative = signed && bytes[i] == b'-';
-    if signed {
-        i += 1;
-    }
-    let start = i;
-    while i < bytes.len() && bytes[i].is_ascii_digit() {
-        i += 1;
-    }
-    let digits = &input[start..i];
-    let rest = &input[i..];
-    if digits.is_empty() {
-        return Err("invalid calendar date".into());
-    }
-    // MM-DD 形式（无年份）
-    if digits.len() == 2 {
-        if !rest.starts_with('-') {
-            return Err("invalid calendar date".into());
-        }
-        let day_part = &rest[1..];
-        if day_part.len() != 2 || !day_part.bytes().all(|byte| byte.is_ascii_digit()) {
-            return Err("invalid calendar day".into());
-        }
-        let month: u32 = digits.parse().map_err(|_| "invalid calendar month".to_string())?;
-        let day: u32 = day_part.parse().map_err(|_| "invalid calendar day".to_string())?;
-        if month == 0 || month > 12 || day == 0 || day > 31 {
-            return Err("invalid calendar date".into());
-        }
-        return Ok(());
-    }
-    if !(4..=6).contains(&digits.len()) {
-        return Err("invalid calendar year".into());
-    }
-    if negative && digits.bytes().all(|byte| byte == b'0') {
-        return Err("invalid calendar negative zero year".into());
-    }
-    let mut rest2 = rest;
-    let mut month: Option<u32> = None;
-    let mut day: Option<u32> = None;
-    if rest2.starts_with('-') {
-        rest2 = &rest2[1..];
-        if rest2.len() < 2 || !rest2.as_bytes()[..2].iter().all(u8::is_ascii_digit) {
-            return Err("invalid calendar month".into());
-        }
-        month = Some(rest2[..2].parse().map_err(|_| "invalid calendar month".to_string())?);
-        rest2 = &rest2[2..];
-        if rest2.starts_with('-') {
-            rest2 = &rest2[1..];
-            if rest2.len() != 2 || !rest2.bytes().all(|byte| byte.is_ascii_digit()) {
-                return Err("invalid calendar day".into());
-            }
-            day = Some(rest2.parse().map_err(|_| "invalid calendar day".to_string())?);
-            rest2 = "";
-        }
-    }
-    if !rest2.is_empty() {
-        return Err("invalid trailing calendar content".into());
-    }
-    if month.is_some_and(|m| m == 0 || m > 12) || day.is_some_and(|d| d == 0 || d > 31) {
-        return Err("invalid calendar date".into());
-    }
-    Ok(())
-}
-
-/// ToTemporalCalendar（宽松版，property bag 路径用）：undefined → None；
-/// string → 宽松解析（白名单 ID 或 ISO 串）；Temporal 实例 → 读日历槽（不触发属性 getter）；
-/// 其他类型 → TypeError。
-fn temporal_calendar_id<H: VmHost>(vm: &mut H, value: JsValue) -> Result<Option<String>, JsValue> {
-    if value.is_undefined() {
-        return Ok(None);
-    }
-    if value.is_string() {
-        return parse_temporal_calendar_string(&to_string(value))
-            .map(Some)
-            .map_err(|_| crate::error::create_range_error(vm, "invalid calendar"));
-    }
-    if value.is_object() {
-        let ptr = value.as_js_object_ptr();
-        if !ptr.is_null() {
-            let obj = unsafe { &*ptr };
-            if obj.is_plain_date_obj() {
-                return Ok(Some(get_calendar_id(obj, 3)));
-            }
-            if obj.is_plain_date_time_obj() {
-                return Ok(Some(get_calendar_id(obj, 4)));
-            }
-            if obj.is_zoned_date_time_obj() {
-                return Ok(Some(get_calendar_id(obj, 2)));
-            }
-            if obj.is_plain_month_day_obj() || obj.is_plain_year_month_obj() {
-                return Ok(Some(get_calendar_id(obj, 3)));
-            }
-        }
-    }
-    Err(crate::error::create_type_error(vm, "invalid calendar"))
-}
-
-/// ToTemporalCalendar 严格版（构造器日历参数用）：字符串只走 18 项白名单，拒绝 ISO 串；
-/// undefined / 其他分支与宽松版一致。
-fn temporal_calendar_id_strict<H: VmHost>(vm: &mut H, value: JsValue) -> Result<Option<String>, JsValue> {
-    if value.is_string() {
-        return parse_temporal_calendar_id_strict(&to_string(value))
-            .map(Some)
-            .map_err(|_| crate::error::create_range_error(vm, "invalid calendar"));
-    }
-    temporal_calendar_id(vm, value)
-}
-
-/// 将 ZonedDateTime 按时区偏移转换为本地 PlainDateTime 分量。
-fn zoned_date_time_plain_parts<H: VmHost>(vm: &mut H, obj: &JsObject) -> Result<(i32, u32, u32, f64), JsValue> {
-    let Some(epoch_ns) = get_instant_epoch_ns(obj) else {
-        return Err(crate::error::create_range_error(vm, "invalid ZonedDateTime"));
-    };
-    let time_zone_id = to_string(obj.get_prop_at(1));
-    let Some(offset_minutes) = instant_time_zone_offset(&time_zone_id) else {
-        return Err(crate::error::create_range_error(vm, "invalid time zone"));
-    };
-    const DAY_NS: i128 = 86_400_000_000_000;
-    let local_ns = epoch_ns + i128::from(offset_minutes) * 60_000_000_000;
-    let days = local_ns.div_euclid(DAY_NS);
-    let time_ns = local_ns.rem_euclid(DAY_NS) as f64;
-    let (year, month, day) = civil_from_days(days);
-    if !valid_plain_date_time_range(year as i32, month as u32, day as u32, time_ns) {
-        return Err(crate::error::create_range_error(vm, "invalid date-time"));
-    }
-    Ok((year as i32, month as u32, day as u32, time_ns))
-}
-
 /// 当地午夜纪元纳秒（含 Instant 范围校验，spec GetStartOfDay 语义）；越界返回 None。
 fn start_of_day_epoch_ns(year: i32, month: u32, day: u32, offset_minutes: i32) -> Option<i128> {
     start_of_day_epoch_ns_by_days(days_from_civil(i128::from(year), i128::from(month), i128::from(day)), offset_minutes)
@@ -5500,18 +4909,6 @@ fn start_of_day_epoch_ns_by_days(days: i128, offset_minutes: i32) -> Option<i128
     (start.unsigned_abs() <= MAX_INSTANT_NS as u128).then_some(start)
 }
 
-/// 本地墙钟分量 + 时区偏移（分钟）→ 纪元纳秒（zoned_date_time_plain_parts 的逆）。
-///
-/// # 边界与前提
-/// - (year, month, day, time_ns) 须已通过 valid_iso_date / valid_plain_time 校验（调用方保证）。
-/// - 仅做 checked 溢出防护，Instant 范围校验由调用方按需执行。
-fn local_to_epoch_ns(year: i32, month: u32, day: u32, time_ns: f64, offset_minutes: i32) -> Option<i128> {
-    let days = days_from_civil(i128::from(year), i128::from(month), i128::from(day));
-    days.checked_mul(86_400_000_000_000)?
-        .checked_add(time_ns as i128)?
-        .checked_sub(i128::from(offset_minutes) * 60_000_000_000)
-}
-
 fn plain_date_time_like_parts<H: VmHost>(
     vm: &mut H, value: JsValue, constrain: bool,
 ) -> Result<(i32, u32, u32, f64, Option<String>), JsValue> {