重构：抽出公历日期基元为独立模块 civil_calendar

- 新增 server-rs/crates/module-runtime/src/civil_calendar.rs：days_in_month / is_leap_year / days_from_civil / civil_from_days / weekday_from_date_key
- application.rs 删除上述重复实现，改为引用新模块，行为不变
- 新模块自带单元测试：闰年规则、日序号往返、已知日期星期
- 后续会员自然月账期、分析维表等纯日期逻辑统一复用该模块

Co-authored-by: Junie <junie@jetbrains.com>

server-rs/crates/module-runtime/src/application.rs

@@ -8,6 +8,9 @@ use serde_json::Value;
 use shared_kernel::{offset_datetime_to_unix_micros, parse_rfc3339};
 use std::collections::{BTreeMap, BTreeSet};
 
+use crate::civil_calendar::{
+    civil_from_days, days_from_civil, days_in_month, is_leap_year, weekday_from_date_key,
+};
 use crate::domain::*;
 use crate::errors::RuntimeProfileFieldError;
 use crate::format_utc_micros;
@@ -1375,25 +1378,6 @@ fn validate_calendar_date(year: i32, month: u8, day: u8) -> Result<(), RuntimePr
     Ok(())
 }
 
-fn days_in_month(year: i32, month: u8) -> u8 {
-    match month {
-        1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
-        4 | 6 | 9 | 11 => 30,
-        2 if is_leap_year(year) => 29,
-        2 => 28,
-        _ => 0,
-    }
-}
-
-fn is_leap_year(year: i32) -> bool {
-    (year % 4 == 0 && year % 100 != 0) || year % 400 == 0
-}
-
-fn weekday_from_date_key(date_key: i64) -> u8 {
-    // 中文注释：1970-01-01 是周四；这里返回 ISO weekday，周一=1，周日=7。
-    (date_key + 3).rem_euclid(7) as u8 + 1
-}
-
 fn iso_week_key(year: i32, month: u8, day: u8, weekday: u8) -> i32 {
     let ordinal = ordinal_day(year, month, day);
     let week = (i32::from(ordinal) - i32::from(weekday) + 10).div_euclid(7);
@@ -1430,36 +1414,6 @@ fn iso_weeks_in_year(year: i32) -> i32 {
     }
 }
 
-fn days_from_civil(year: i32, month: u8, day: u8) -> i64 {
-    // 中文注释：Howard Hinnant civil calendar 算法，返回 1970-01-01 起的日序号。
-    let adjusted_year = year - if month <= 2 { 1 } else { 0 };
-    let era = adjusted_year.div_euclid(400);
-    let year_of_era = adjusted_year - era * 400;
-    let month = i32::from(month);
-    let day = i32::from(day);
-    let month_prime = month + if month > 2 { -3 } else { 9 };
-    let day_of_year = (153 * month_prime + 2) / 5 + day - 1;
-    let day_of_era = year_of_era * 365 + year_of_era / 4 - year_of_era / 100 + day_of_year;
-    i64::from(era * 146_097 + day_of_era - 719_468)
-}
-
-fn civil_from_days(date_key: i64) -> (i32, u8, u8) {
-    // 中文注释：days_from_civil 的反向算法，避免依赖运行环境时区。
-    let z = date_key + 719_468;
-    let era = z.div_euclid(146_097);
-    let day_of_era = z - 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)
-        .div_euclid(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).div_euclid(153);
-    let day = day_of_year - (153 * month_prime + 2).div_euclid(5) + 1;
-    let month = month_prime + if month_prime < 10 { 3 } else { -9 };
-    year += if month <= 2 { 1 } else { 0 };
-    (year as i32, month as u8, day as u8)
-}
-
 pub fn build_default_runtime_profile_task_config(
     updated_at_micros: i64,
     updated_by: String,

server-rs/crates/module-runtime/src/civil_calendar.rs

@@ -0,0 +1,94 @@
+//! 公历日期基元（不依赖运行环境时区）。
+//!
+//! 只做「公历年月日 ↔ 1970-01-01 起日序号」的纯换算，采用 Howard Hinnant 的 civil calendar
+//! 算法。北京时间（UTC+8）与业务日边界由调用方叠加固定偏移，因此本模块永远不读系统时区。
+
+/// 公历给定年月的天数，含闰年规则。
+pub fn days_in_month(year: i32, month: u8) -> u8 {
+    match month {
+        1 | 3 | 5 | 7 | 8 | 10 | 12 => 31,
+        4 | 6 | 9 | 11 => 30,
+        2 if is_leap_year(year) => 29,
+        2 => 28,
+        _ => 0,
+    }
+}
+
+/// 公历闰年判断。
+pub fn is_leap_year(year: i32) -> bool {
+    (year % 4 == 0 && year % 100 != 0) || year % 400 == 0
+}
+
+/// 公历年月日 → 1970-01-01 起的日序号。
+pub fn days_from_civil(year: i32, month: u8, day: u8) -> i64 {
+    // 中文注释：Howard Hinnant civil calendar 算法，返回 1970-01-01 起的日序号。
+    let adjusted_year = year - if month <= 2 { 1 } else { 0 };
+    let era = adjusted_year.div_euclid(400);
+    let year_of_era = adjusted_year - era * 400;
+    let month = i32::from(month);
+    let day = i32::from(day);
+    let month_prime = month + if month > 2 { -3 } else { 9 };
+    let day_of_year = (153 * month_prime + 2) / 5 + day - 1;
+    let day_of_era = year_of_era * 365 + year_of_era / 4 - year_of_era / 100 + day_of_year;
+    i64::from(era * 146_097 + day_of_era - 719_468)
+}
+
+/// 1970-01-01 起的日序号 → 公历年月日。
+pub fn civil_from_days(date_key: i64) -> (i32, u8, u8) {
+    // 中文注释：days_from_civil 的反向算法，避免依赖运行环境时区。
+    let z = date_key + 719_468;
+    let era = z.div_euclid(146_097);
+    let day_of_era = z - 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)
+        .div_euclid(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).div_euclid(153);
+    let day = day_of_year - (153 * month_prime + 2).div_euclid(5) + 1;
+    let month = month_prime + if month_prime < 10 { 3 } else { -9 };
+    year += if month <= 2 { 1 } else { 0 };
+    (year as i32, month as u8, day as u8)
+}
+
+/// ISO 星期：周一 = 1，周日 = 7。
+pub fn weekday_from_date_key(date_key: i64) -> u8 {
+    // 中文注释：1970-01-01 是周四；这里返回 ISO weekday，周一=1，周日=7。
+    (date_key + 3).rem_euclid(7) as u8 + 1
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn civil_round_trip_holds_across_month_and_year_boundaries() {
+        for (year, month, day) in [
+            (2024, 2, 29),
+            (2026, 1, 1),
+            (2026, 12, 31),
+            (1970, 1, 1),
+            (2100, 12, 31),
+        ] {
+            let date_key = days_from_civil(year, month, day);
+            assert_eq!(civil_from_days(date_key), (year, month, day));
+        }
+    }
+
+    #[test]
+    fn days_in_month_applies_leap_year_rules() {
+        assert_eq!(days_in_month(2024, 2), 29);
+        assert_eq!(days_in_month(2023, 2), 28);
+        assert_eq!(days_in_month(2100, 2), 28);
+        assert_eq!(days_in_month(2000, 2), 29);
+        assert_eq!(days_in_month(2026, 4), 30);
+        assert_eq!(days_in_month(2026, 12), 31);
+    }
+
+    #[test]
+    fn weekday_from_date_key_matches_known_dates() {
+        // 中文注释：1970-01-01 是周四；2026-01-01 也是周四。
+        assert_eq!(weekday_from_date_key(days_from_civil(1970, 1, 1)), 4);
+        assert_eq!(weekday_from_date_key(days_from_civil(2026, 1, 1)), 4);
+    }
+}

server-rs/crates/module-runtime/src/lib.rs

@@ -1,5 +1,7 @@
 pub mod agc_analytics;
 mod agc_models;
+pub mod civil_calendar;
+pub use civil_calendar::*;
 mod llm_billing;
 pub use llm_billing::*;
 mod application;