feat: v2.1.0 — delegate engine logic to hijri-core

All Hijri conversion logic (UAQ table, FCNA algorithm, month/weekday
names, isValidHijriDate) now lives in hijri-core and is re-exported
from this package with identical signatures. Zero breaking changes:
the public API surface, type exports, and behavior are unchanged.

src/fcna.ts removed — FCNA engine is in hijri-core.
src/hDates.ts, hMonths.ts, hWeekdays.ts, utils.ts, toHijri.ts,
toGregorian.ts all rewritten as thin re-exports or single-line wrappers.

hijri-core added as a runtime dependency.

CHANGELOG.md

@@ -1,9 +1,19 @@
 # Changelog
 
+<!-- markdownlint-disable MD024 -->
+
 All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [2.1.0] - 2026-02-25
+
+### Changed
+
+- Engine logic extracted to `hijri-core` (new dependency). All Hijri conversion algorithms now live in that package and are re-exported from `luxon-hijri` with identical signatures. Zero breaking changes to the public API.
+- `src/hDates.ts`, `src/hMonths.ts`, `src/hWeekdays.ts`, `src/fcna.ts`, `src/utils.ts`, `src/toHijri.ts`, `src/toGregorian.ts` — all now delegate to `hijri-core`. The UAQ table, FCNA engine, month/weekday names, and conversion functions have a single source of truth across the hijri ecosystem.
+- `hijri-core ^1.0.0` added as a runtime dependency. `luxon` stays as a runtime dependency (still needed by `formatHijriDate` for time and timezone tokens).
+
 ## [2.0.0] - 2026-02-25
 
 ### Added

package.json

@@ -1,6 +1,6 @@
 {
   "name": "luxon-hijri",
-  "version": "2.0.0",
+  "version": "2.1.0",
   "description": "Hijri/Gregorian date conversion and formatting using the Umm al-Qura calendar. Built on Luxon. Supports toHijri, toGregorian, formatHijriDate, and isValidHijriDate.",
   "author": "Aric Camarata",
   "license": "MIT",
@@ -53,6 +53,7 @@
     "typescript"
   ],
   "dependencies": {
+    "hijri-core": "file:../hijri-core",
     "luxon": "^3.5.0"
   },
   "devDependencies": {

pnpm-lock.yaml

@@ -8,6 +8,9 @@ importers:
 
   .:
     dependencies:
+      hijri-core:
+        specifier: file:../hijri-core
+        version: file:../hijri-core
       luxon:
         specifier: ^3.5.0
         version: 3.7.2
@@ -407,6 +410,10 @@ packages:
     engines: {node: ^8.16.0 || ^10.6.0 || >=11.0.0}
     os: [darwin]
 
+  hijri-core@file:../hijri-core:
+    resolution: {directory: ../hijri-core, type: directory}
+    engines: {node: '>=20'}
+
   joycon@3.1.1:
     resolution: {integrity: sha512-34wB/Y7MW7bzjKRjUKTa46I2Z7eV62Rkhva+KkopW7Qvv/OSWBqvkSY7vusOPrNuZcUG3tApvdVgNB8POj3SPw==}
     engines: {node: '>=10'}
@@ -794,6 +801,8 @@ snapshots:
   fsevents@2.3.3:
     optional: true
 
+  hijri-core@file:../hijri-core: {}
+
   joycon@3.1.1: {}
 
   lilconfig@3.1.3: {}

src/fcna.ts

@@ -1,301 +0,0 @@
-// fcna.ts — FCNA/ISNA Hijri calendar engine
-//
-// The Fiqh Council of North America (FCNA) uses a global astronomical criterion:
-// if the new moon conjunction occurs before 12:00 noon UTC on day D, the new
-// Hijri month begins at midnight starting day D+1 (next calendar day); if at or
-// after 12:00 UTC, the month begins at midnight starting day D+2.
-//
-// For years in the Umm al-Qura table (1318–1500 H), the UAQ month start date
-// serves as the anchor for locating the nearest new moon. For years outside that
-// range the anchor comes from the Islamic epoch plus mean synodic months.
-//
-// New moon times come from Jean Meeus, Astronomical Algorithms (2nd ed.),
-// Chapter 49 — accurate to within a few minutes for 1000 CE to 3000 CE.
-
-import { hDatesTable } from './hDates';
-import type { HijriDate } from './types';
-
-// ─── Constants ───────────────────────────────────────────────────────────────
-
-const SYNODIC     = 29.530588861;   // Mean synodic month (days)
-const JDE0        = 2451550.09766;  // Meeus k=0: mean new moon ~2000-01-06
-const JDE_UNIX    = 2440587.5;      // JDE of Unix epoch 1970-01-01 00:00 UTC
-const MS_PER_DAY  = 86_400_000;
-const TO_RAD      = Math.PI / 180;
-
-// Approximate k index of 1 Muharram 1 AH in Meeus numbering.
-// Derived: Islamic epoch JDE ≈ 1948438.5 → k ≈ (1948438.5 − JDE0) / SYNODIC ≈ −17037.
-const K_EPOCH = -17037;
-
-// ─── Meeus Chapter 49: corrected new moon JDE ────────────────────────────────
-
-function newMoonJDE(k: number): number {
-  const T  = k / 1236.85;
-  const T2 = T * T;
-  const T3 = T2 * T;
-  const T4 = T3 * T;
-
-  // Mean JDE (Meeus Eq. 49.1)
-  let jde = JDE0
-    + SYNODIC * k
-    + 0.00015437 * T2
-    - 0.000000150 * T3
-    + 0.00000000073 * T4;
-
-  // Sun's mean anomaly M (degrees)
-  const M = (2.5534
-    + 29.10535670 * k
-    - 0.0000014 * T2
-    - 0.00000011 * T3) % 360;
-
-  // Moon's mean anomaly M' (degrees)
-  const Mprime = (201.5643
-    + 385.81693528 * k
-    + 0.0107582 * T2
-    + 0.00001238 * T3
-    - 0.000000058 * T4) % 360;
-
-  // Moon's argument of latitude F (degrees)
-  const F = (160.7108
-    + 390.67050284 * k
-    - 0.0016118 * T2
-    - 0.00000227 * T3
-    + 0.000000011 * T4) % 360;
-
-  // Longitude of ascending node Omega (degrees)
-  const Omega = (124.7746
-    - 1.56375588 * k
-    + 0.0020672 * T2
-    + 0.00000215 * T3) % 360;
-
-  // Eccentricity correction factor E
-  const E  = 1 - 0.002516 * T - 0.0000074 * T2;
-  const E2 = E * E;
-
-  // Angles to radians
-  const Mrad  = M * TO_RAD;
-  const Mprad = Mprime * TO_RAD;
-  const Frad  = F * TO_RAD;
-  const Orad  = Omega * TO_RAD;
-
-  // Planetary correction (Meeus Table 49.a — new moon phase)
-  jde +=
-    - 0.40720 * Math.sin(Mprad)
-    + 0.17241 * E  * Math.sin(Mrad)
-    + 0.01608 * Math.sin(2 * Mprad)
-    + 0.01039 * Math.sin(2 * Frad)
-    + 0.00739 * E  * Math.sin(Mprad - Mrad)
-    - 0.00514 * E  * Math.sin(Mprad + Mrad)
-    + 0.00208 * E2 * Math.sin(2 * Mrad)
-    - 0.00111 * Math.sin(Mprad - 2 * Frad)
-    - 0.00057 * Math.sin(Mprad + 2 * Frad)
-    + 0.00056 * E  * Math.sin(2 * Mprad + Mrad)
-    - 0.00042 * Math.sin(3 * Mprad)
-    + 0.00042 * E  * Math.sin(Mrad + 2 * Frad)
-    + 0.00038 * E  * Math.sin(Mrad - 2 * Frad)
-    - 0.00024 * E  * Math.sin(2 * Mprad - Mrad)
-    - 0.00017 * Math.sin(Orad)
-    - 0.00007 * Math.sin(Mprad + 2 * Mrad)
-    + 0.00004 * Math.sin(2 * Mprad - 2 * Frad)
-    + 0.00004 * Math.sin(3 * Mrad)
-    + 0.00003 * Math.sin(Mprad + Mrad - 2 * Frad)
-    + 0.00003 * Math.sin(2 * Mprad + 2 * Frad)
-    - 0.00003 * Math.sin(Mprad + Mrad + 2 * Frad)
-    + 0.00003 * Math.sin(Mprad - Mrad + 2 * Frad)
-    - 0.00002 * Math.sin(Mprad - Mrad - 2 * Frad)
-    - 0.00002 * Math.sin(3 * Mprad + Mrad)
-    + 0.00002 * Math.sin(4 * Mprad);
-
-  // Additional planetary corrections (Meeus Table 49.b)
-  const A1  = (299.77 +  0.107408 * k - 0.009173 * T2) * TO_RAD;
-  const A2  = (251.88 +  0.016321 * k) * TO_RAD;
-  const A3  = (251.83 + 26.651886 * k) * TO_RAD;
-  const A4  = (349.42 + 36.412478 * k) * TO_RAD;
-  const A5  = ( 84.66 + 18.206239 * k) * TO_RAD;
-  const A6  = (141.74 + 53.303771 * k) * TO_RAD;
-  const A7  = (207.14 +  2.453732 * k) * TO_RAD;
-  const A8  = (154.84 +  7.306860 * k) * TO_RAD;
-  const A9  = ( 34.52 + 27.261239 * k) * TO_RAD;
-  const A10 = (207.19 +  0.121824 * k) * TO_RAD;
-  const A11 = (291.34 +  1.844379 * k) * TO_RAD;
-  const A12 = (161.72 + 24.198154 * k) * TO_RAD;
-  const A13 = (239.56 + 25.513099 * k) * TO_RAD;
-  const A14 = (331.55 +  3.592518 * k) * TO_RAD;
-
-  jde +=
-    + 0.000325 * Math.sin(A1)
-    + 0.000165 * Math.sin(A2)
-    + 0.000164 * Math.sin(A3)
-    + 0.000126 * Math.sin(A4)
-    + 0.000110 * Math.sin(A5)
-    + 0.000062 * Math.sin(A6)
-    + 0.000060 * Math.sin(A7)
-    + 0.000056 * Math.sin(A8)
-    + 0.000047 * Math.sin(A9)
-    + 0.000042 * Math.sin(A10)
-    + 0.000040 * Math.sin(A11)
-    + 0.000037 * Math.sin(A12)
-    + 0.000035 * Math.sin(A13)
-    + 0.000023 * Math.sin(A14);
-
-  return jde;
-}
-
-// ─── JDE / UTC conversion ─────────────────────────────────────────────────────
-
-function jdeToUtcMs(jde: number): number {
-  return (jde - JDE_UNIX) * MS_PER_DAY;
-}
-
-function utcMsToKApprox(ms: number): number {
-  const jde = ms / MS_PER_DAY + JDE_UNIX;
-  return (jde - JDE0) / SYNODIC;
-}
-
-// ─── Find nearest corrected new moon ─────────────────────────────────────────
-
-// Returns the UTC ms of the corrected new moon closest to anchorMs.
-// Searches k0-2 through k0+2 (5 candidates) to handle any estimation error.
-function nearestNewMoonMs(anchorMs: number): number {
-  const k0 = Math.round(utcMsToKApprox(anchorMs));
-  let bestMs   = 0;
-  let bestDist = Infinity;
-
-  for (let k = k0 - 2; k <= k0 + 2; k++) {
-    const ms   = jdeToUtcMs(newMoonJDE(k));
-    const dist = Math.abs(ms - anchorMs);
-    if (dist < bestDist) {
-      bestDist = dist;
-      bestMs   = ms;
-    }
-  }
-
-  return bestMs;
-}
-
-// ─── FCNA criterion ──────────────────────────────────────────────────────────
-
-// Given a conjunction UTC ms, return the midnight UTC ms that starts the
-// new FCNA Hijri month: D+1 if conjunction before 12:00 UTC, D+2 otherwise.
-function fcnaCriterionMs(conjMs: number): number {
-  const midnight = Math.floor(conjMs / MS_PER_DAY) * MS_PER_DAY;
-  const noon     = midnight + 12 * 3_600_000;
-  return conjMs < noon ? midnight + MS_PER_DAY : midnight + 2 * MS_PER_DAY;
-}
-
-// ─── UAQ anchor ──────────────────────────────────────────────────────────────
-
-// Return the UTC ms of the UAQ month start for (hy, hm).
-// For years 1318–1500 H: binary-search hDatesTable, sum dpm day counts.
-// For years outside that range: estimate from Islamic epoch + mean month count.
-export function uaqAnchorMs(hy: number, hm: number): number {
-  // Binary search for hy in table.
-  let lo = 0, hi = hDatesTable.length - 1, found = -1;
-  while (lo <= hi) {
-    const mid = (lo + hi) >>> 1;
-    const midHy = hDatesTable[mid].hy;
-    if (midHy === hy)      { found = mid; break; }
-    else if (midHy < hy)  lo = mid + 1;
-    else                   hi = mid - 1;
-  }
-
-  if (found !== -1 && hDatesTable[found].dpm !== 0) {
-    // In-range: sum prior-month day counts from table start date.
-    const r = hDatesTable[found];
-    let days = 0;
-    for (let i = 0; i < hm - 1; i++) {
-      days += (r.dpm >> i) & 1 ? 30 : 29;
-    }
-    return Date.UTC(r.gy, r.gm - 1, r.gd) + days * MS_PER_DAY;
-  }
-
-  // Out of range: estimate from Islamic epoch + mean months elapsed.
-  const monthsFromEpoch = (hy - 1) * 12 + (hm - 1);
-  const kApprox = K_EPOCH + monthsFromEpoch;
-  return jdeToUtcMs(newMoonJDE(kApprox));
-}
-
-// ─── FCNA month start ─────────────────────────────────────────────────────────
-
-// Return UTC ms of midnight beginning the given FCNA Hijri month.
-export function fcnaMonthStartMs(hy: number, hm: number): number {
-  const anchor = uaqAnchorMs(hy, hm);
-  const conjMs = nearestNewMoonMs(anchor);
-  return fcnaCriterionMs(conjMs);
-}
-
-// ─── FCNA month length ───────────────────────────────────────────────────────
-
-export function fcnaDaysInMonth(hy: number, hm: number): number {
-  const thisStart = fcnaMonthStartMs(hy, hm);
-  const nextHy    = hm < 12 ? hy : hy + 1;
-  const nextHm    = hm < 12 ? hm + 1 : 1;
-  const nextStart = fcnaMonthStartMs(nextHy, nextHm);
-  return Math.round((nextStart - thisStart) / MS_PER_DAY);
-}
-
-// ─── FCNA Gregorian → Hijri ──────────────────────────────────────────────────
-
-export function fcnaToHijri(gregorianDate: Date): HijriDate | null {
-  if (!(gregorianDate instanceof Date) || isNaN(gregorianDate.getTime())) {
-    throw new Error('Invalid Gregorian date');
-  }
-
-  // Use UTC date components. The FCNA criterion is UTC-based (conjunction before
-  // 12:00 UTC), so month boundaries are defined in UTC. Using UTC methods ensures
-  // fcnaToGregorian ↔ fcnaToHijri round-trips correctly in any host timezone.
-  const inputMs = Date.UTC(
-    gregorianDate.getUTCFullYear(),
-    gregorianDate.getUTCMonth(),
-    gregorianDate.getUTCDate(),
-  );
-
-  // Shift back ~15 days before estimating k so that kApprox resolves to the
-  // current month's conjunction rather than possibly the next month's.
-  const kApprox = utcMsToKApprox(inputMs - 15 * MS_PER_DAY);
-  const k0      = Math.floor(kApprox);
-
-  // Search k0-1, k0, k0+1 for the FCNA month containing inputMs.
-  for (let ki = k0 - 1; ki <= k0 + 1; ki++) {
-    const conjMs      = jdeToUtcMs(newMoonJDE(ki));
-    const monthStart  = fcnaCriterionMs(conjMs);
-
-    if (monthStart > inputMs) continue;
-
-    const nextConjMs    = jdeToUtcMs(newMoonJDE(ki + 1));
-    const nextMonthStart = fcnaCriterionMs(nextConjMs);
-
-    if (inputMs < nextMonthStart) {
-      // inputMs falls in the month that began at monthStart (k = ki).
-      // Map ki → Hijri (hy, hm) via K_EPOCH offset.
-      const monthsFromEpoch = ki - K_EPOCH;
-      let hy = Math.floor(monthsFromEpoch / 12) + 1;
-      let hm = (monthsFromEpoch % 12) + 1;
-      // JavaScript % can return negative; normalize to 1–12.
-      if (hm <= 0) { hm += 12; hy--; }
-      if (hy < 1) return null;  // before 1 AH
-
-      const hd = Math.round((inputMs - monthStart) / MS_PER_DAY) + 1;
-      return { hy, hm, hd };
-    }
-  }
-
-  return null;
-}
-
-// ─── FCNA Hijri → Gregorian ──────────────────────────────────────────────────
-
-export function fcnaToGregorian(hy: number, hm: number, hd: number): Date | null {
-  if (hy < 1 || hm < 1 || hm > 12 || hd < 1) return null;
-  const days = fcnaDaysInMonth(hy, hm);
-  if (hd > days) return null;
-  const startMs = fcnaMonthStartMs(hy, hm);
-  return new Date(startMs + (hd - 1) * MS_PER_DAY);
-}
-
-// ─── FCNA validation ─────────────────────────────────────────────────────────
-
-export function fcnaIsValid(hy: number, hm: number, hd: number): boolean {
-  if (hy < 1 || hm < 1 || hm > 12 || hd < 1) return false;
-  return hd <= fcnaDaysInMonth(hy, hm);
-}

src/hDates.ts

@@ -1,191 +1,3 @@
-// hDates.ts
-// Hijri Dates Reference Table
-import { HijriYearRecord } from './types';
-
-export type { HijriYearRecord };
-
-export const hDatesTable: HijriYearRecord[] = [
-    { hy: 1318, dpm: 0x02EA, gy: 1900, gm:  4, gd: 30 },
-    { hy: 1319, dpm: 0x06E9, gy: 1901, gm:  4, gd: 19 },
-    { hy: 1320, dpm: 0x0ED2, gy: 1902, gm:  4, gd: 9  },
-    { hy: 1321, dpm: 0x0EA4, gy: 1903, gm:  3, gd: 30 },
-    { hy: 1322, dpm: 0x0D4A, gy: 1904, gm:  3, gd: 18 },
-    { hy: 1323, dpm: 0x0A96, gy: 1905, gm:  3, gd: 7  },
-    { hy: 1324, dpm: 0x0536, gy: 1906, gm:  2, gd: 24 },
-    { hy: 1325, dpm: 0x0AB5, gy: 1907, gm:  2, gd: 13 },
-    { hy: 1326, dpm: 0x0DAA, gy: 1908, gm:  2, gd: 3  },
-    { hy: 1327, dpm: 0x0BA4, gy: 1909, gm:  1, gd: 23 },
-    { hy: 1328, dpm: 0x0B49, gy: 1910, gm:  1, gd: 12 },
-    { hy: 1329, dpm: 0x0A93, gy: 1911, gm:  1, gd: 1  },
-    { hy: 1330, dpm: 0x052B, gy: 1911, gm: 12, gd: 21 },
-    { hy: 1331, dpm: 0x0A57, gy: 1912, gm: 12, gd: 9  },
-    { hy: 1332, dpm: 0x04B6, gy: 1913, gm: 11, gd: 29 },
-    { hy: 1333, dpm: 0x0AB5, gy: 1914, gm: 11, gd: 18 },
-    { hy: 1334, dpm: 0x05AA, gy: 1915, gm: 11, gd: 8  },
-    { hy: 1335, dpm: 0x0D55, gy: 1916, gm: 10, gd: 27 },
-    { hy: 1336, dpm: 0x0D2A, gy: 1917, gm: 10, gd: 17 },
-    { hy: 1337, dpm: 0x0A56, gy: 1918, gm: 10, gd: 6  },
-    { hy: 1338, dpm: 0x04AE, gy: 1919, gm:  9, gd: 25 },
-    { hy: 1339, dpm: 0x095D, gy: 1920, gm:  9, gd: 13 },
-    { hy: 1340, dpm: 0x02EC, gy: 1921, gm:  9, gd: 3  },
-    { hy: 1341, dpm: 0x06D5, gy: 1922, gm:  8, gd: 23 },
-    { hy: 1342, dpm: 0x06AA, gy: 1923, gm:  8, gd: 13 },
-    { hy: 1343, dpm: 0x0555, gy: 1924, gm:  8, gd: 1  },
-    { hy: 1344, dpm: 0x04AB, gy: 1925, gm:  7, gd: 21 },
-    { hy: 1345, dpm: 0x095B, gy: 1926, gm:  7, gd: 10 },
-    { hy: 1346, dpm: 0x02BA, gy: 1927, gm:  6, gd: 30 },
-    { hy: 1347, dpm: 0x0575, gy: 1928, gm:  6, gd: 18 },
-    { hy: 1348, dpm: 0x0BB2, gy: 1929, gm:  6, gd: 8  },
-    { hy: 1349, dpm: 0x0764, gy: 1930, gm:  5, gd: 29 },
-    { hy: 1350, dpm: 0x0749, gy: 1931, gm:  5, gd: 18 },
-    { hy: 1351, dpm: 0x0655, gy: 1932, gm:  5, gd: 6  },
-    { hy: 1352, dpm: 0x02AB, gy: 1933, gm:  4, gd: 25 },
-    { hy: 1353, dpm: 0x055B, gy: 1934, gm:  4, gd: 14 },
-    { hy: 1354, dpm: 0x0ADA, gy: 1935, gm:  4, gd: 4  },
-    { hy: 1355, dpm: 0x06D4, gy: 1936, gm:  3, gd: 24 },
-    { hy: 1356, dpm: 0x0EC9, gy: 1937, gm:  3, gd: 13 },
-    { hy: 1357, dpm: 0x0D92, gy: 1938, gm:  3, gd: 3  },
-    { hy: 1358, dpm: 0x0D25, gy: 1939, gm:  2, gd: 20 },
-    { hy: 1359, dpm: 0x0A4D, gy: 1940, gm:  2, gd: 9  },
-    { hy: 1360, dpm: 0x02AD, gy: 1941, gm:  1, gd: 28 },
-    { hy: 1361, dpm: 0x056D, gy: 1942, gm:  1, gd: 17 },
-    { hy: 1362, dpm: 0x0B6A, gy: 1943, gm:  1, gd: 7  },
-    { hy: 1363, dpm: 0x0B52, gy: 1943, gm: 12, gd: 28 },
-    { hy: 1364, dpm: 0x0AA5, gy: 1944, gm: 12, gd: 16 },
-    { hy: 1365, dpm: 0x0A4B, gy: 1945, gm: 12, gd: 5  },
-    { hy: 1366, dpm: 0x0497, gy: 1946, gm: 11, gd: 24 },
-    { hy: 1367, dpm: 0x0937, gy: 1947, gm: 11, gd: 13 },
-    { hy: 1368, dpm: 0x02B6, gy: 1948, gm: 11, gd: 2  },
-    { hy: 1369, dpm: 0x0575, gy: 1949, gm: 10, gd: 22 },
-    { hy: 1370, dpm: 0x0D6A, gy: 1950, gm: 10, gd: 12 },
-    { hy: 1371, dpm: 0x0D52, gy: 1951, gm: 10, gd: 2  },
-    { hy: 1372, dpm: 0x0A96, gy: 1952, gm:  9, gd: 20 },
-    { hy: 1373, dpm: 0x092D, gy: 1953, gm:  9, gd: 9  },
-    { hy: 1374, dpm: 0x025D, gy: 1954, gm:  8, gd: 29 },
-    { hy: 1375, dpm: 0x04DD, gy: 1955, gm:  8, gd: 18 },
-    { hy: 1376, dpm: 0x0ADA, gy: 1956, gm:  8, gd: 7  },
-    { hy: 1377, dpm: 0x05D4, gy: 1957, gm:  7, gd: 28 },
-    { hy: 1378, dpm: 0x0DA9, gy: 1958, gm:  7, gd: 17 },
-    { hy: 1379, dpm: 0x0D52, gy: 1959, gm:  7, gd: 7  },
-    { hy: 1380, dpm: 0x0AAA, gy: 1960, gm:  6, gd: 25 },
-    { hy: 1381, dpm: 0x04D6, gy: 1961, gm:  6, gd: 14 },
-    { hy: 1382, dpm: 0x09B6, gy: 1962, gm:  6, gd: 3  },
-    { hy: 1383, dpm: 0x0374, gy: 1963, gm:  5, gd: 24 },
-    { hy: 1384, dpm: 0x0769, gy: 1964, gm:  5, gd: 12 },
-    { hy: 1385, dpm: 0x0752, gy: 1965, gm:  5, gd: 2  },
-    { hy: 1386, dpm: 0x06A5, gy: 1966, gm:  4, gd: 21 },
-    { hy: 1387, dpm: 0x054B, gy: 1967, gm:  4, gd: 10 },
-    { hy: 1388, dpm: 0x0AAB, gy: 1968, gm:  3, gd: 29 },
-    { hy: 1389, dpm: 0x055A, gy: 1969, gm:  3, gd: 19 },
-    { hy: 1390, dpm: 0x0AD5, gy: 1970, gm:  3, gd: 8  },
-    { hy: 1391, dpm: 0x0DD2, gy: 1971, gm:  2, gd: 26 },
-    { hy: 1392, dpm: 0x0DA4, gy: 1972, gm:  2, gd: 16 },
-    { hy: 1393, dpm: 0x0D49, gy: 1973, gm:  2, gd: 4  },
-    { hy: 1394, dpm: 0x0A95, gy: 1974, gm:  1, gd: 24 },
-    { hy: 1395, dpm: 0x052D, gy: 1975, gm:  1, gd: 13 },
-    { hy: 1396, dpm: 0x0A5D, gy: 1976, gm:  1, gd: 2  },
-    { hy: 1397, dpm: 0x055A, gy: 1976, gm: 12, gd: 22 },
-    { hy: 1398, dpm: 0x0AD5, gy: 1977, gm: 12, gd: 11 },
-    { hy: 1399, dpm: 0x06AA, gy: 1978, gm: 12, gd: 1  },
-    { hy: 1400, dpm: 0x0695, gy: 1979, gm: 11, gd: 20 },
-    { hy: 1401, dpm: 0x052B, gy: 1980, gm: 11, gd: 8  },
-    { hy: 1402, dpm: 0x0A57, gy: 1981, gm: 10, gd: 28 },
-    { hy: 1403, dpm: 0x04AE, gy: 1982, gm: 10, gd: 18 },
-    { hy: 1404, dpm: 0x0976, gy: 1983, gm: 10, gd: 7  },
-    { hy: 1405, dpm: 0x056C, gy: 1984, gm:  9, gd: 26 },
-    { hy: 1406, dpm: 0x0B55, gy: 1985, gm:  9, gd: 15 },
-    { hy: 1407, dpm: 0x0AAA, gy: 1986, gm:  9, gd: 5  },
-    { hy: 1408, dpm: 0x0A55, gy: 1987, gm:  8, gd: 25 },
-    { hy: 1409, dpm: 0x04AD, gy: 1988, gm:  8, gd: 13 },
-    { hy: 1410, dpm: 0x095D, gy: 1989, gm:  8, gd: 2  },
-    { hy: 1411, dpm: 0x02DA, gy: 1990, gm:  7, gd: 23 },
-    { hy: 1412, dpm: 0x05D9, gy: 1991, gm:  7, gd: 12 },
-    { hy: 1413, dpm: 0x0DB2, gy: 1992, gm:  7, gd: 1  },
-    { hy: 1414, dpm: 0x0BA4, gy: 1993, gm:  6, gd: 21 },
-    { hy: 1415, dpm: 0x0B4A, gy: 1994, gm:  6, gd: 10 },
-    { hy: 1416, dpm: 0x0A55, gy: 1995, gm:  5, gd: 30 },
-    { hy: 1417, dpm: 0x02B5, gy: 1996, gm:  5, gd: 18 },
-    { hy: 1418, dpm: 0x0575, gy: 1997, gm:  5, gd: 7  },
-    { hy: 1419, dpm: 0x0B6A, gy: 1998, gm:  4, gd: 27 },
-    { hy: 1420, dpm: 0x0BD2, gy: 1999, gm:  4, gd: 17 },
-    { hy: 1421, dpm: 0x0BC4, gy: 2000, gm:  4, gd: 6  },
-    { hy: 1422, dpm: 0x0B89, gy: 2001, gm:  3, gd: 26 },
-    { hy: 1423, dpm: 0x0A95, gy: 2002, gm:  3, gd: 15 },
-    { hy: 1424, dpm: 0x052D, gy: 2003, gm:  3, gd: 4  },
-    { hy: 1425, dpm: 0x05AD, gy: 2004, gm:  2, gd: 21 },
-    { hy: 1426, dpm: 0x0B6A, gy: 2005, gm:  2, gd: 10 },
-    { hy: 1427, dpm: 0x06D4, gy: 2006, gm:  1, gd: 31 },
-    { hy: 1428, dpm: 0x0DC9, gy: 2007, gm:  1, gd: 20 },
-    { hy: 1429, dpm: 0x0D92, gy: 2008, gm:  1, gd: 10 },
-    { hy: 1430, dpm: 0x0AA6, gy: 2008, gm: 12, gd: 29 },
-    { hy: 1431, dpm: 0x0956, gy: 2009, gm: 12, gd: 18 },
-    { hy: 1432, dpm: 0x02AE, gy: 2010, gm: 12, gd: 7  },
-    { hy: 1433, dpm: 0x056D, gy: 2011, gm: 11, gd: 26 },
-    { hy: 1434, dpm: 0x036A, gy: 2012, gm: 11, gd: 15 },
-    { hy: 1435, dpm: 0x0B55, gy: 2013, gm: 11, gd: 4  },
-    { hy: 1436, dpm: 0x0AAA, gy: 2014, gm: 10, gd: 25 },
-    { hy: 1437, dpm: 0x094D, gy: 2015, gm: 10, gd: 14 },
-    { hy: 1438, dpm: 0x049D, gy: 2016, gm: 10, gd: 2  },
-    { hy: 1439, dpm: 0x095D, gy: 2017, gm:  9, gd: 21 },
-    { hy: 1440, dpm: 0x02BA, gy: 2018, gm:  9, gd: 11 },
-    { hy: 1441, dpm: 0x05B5, gy: 2019, gm:  8, gd: 31 },
-    { hy: 1442, dpm: 0x05AA, gy: 2020, gm:  8, gd: 20 },
-    { hy: 1443, dpm: 0x0D55, gy: 2021, gm:  8, gd: 9  },
-    { hy: 1444, dpm: 0x0A9A, gy: 2022, gm:  7, gd: 30 },
-    { hy: 1445, dpm: 0x092E, gy: 2023, gm:  7, gd: 19 },
-    { hy: 1446, dpm: 0x026E, gy: 2024, gm:  7, gd: 7  },
-    { hy: 1447, dpm: 0x055D, gy: 2025, gm:  6, gd: 26 },
-    { hy: 1448, dpm: 0x0ADA, gy: 2026, gm:  6, gd: 16 },
-    { hy: 1449, dpm: 0x06D4, gy: 2027, gm:  6, gd: 6  },
-    { hy: 1450, dpm: 0x06A5, gy: 2028, gm:  5, gd: 25 },
-    { hy: 1451, dpm: 0x054B, gy: 2029, gm:  5, gd: 14 },
-    { hy: 1452, dpm: 0x0A97, gy: 2030, gm:  5, gd: 3  },
-    { hy: 1453, dpm: 0x054E, gy: 2031, gm:  4, gd: 23 },
-    { hy: 1454, dpm: 0x0AAE, gy: 2032, gm:  4, gd: 11 },
-    { hy: 1455, dpm: 0x05AC, gy: 2033, gm:  4, gd: 1  },
-    { hy: 1456, dpm: 0x0BA9, gy: 2034, gm:  3, gd: 21 },
-    { hy: 1457, dpm: 0x0D92, gy: 2035, gm:  3, gd: 11 },
-    { hy: 1458, dpm: 0x0B25, gy: 2036, gm:  2, gd: 28 },
-    { hy: 1459, dpm: 0x064B, gy: 2037, gm:  2, gd: 16 },
-    { hy: 1460, dpm: 0x0CAB, gy: 2038, gm:  2, gd: 5  },
-    { hy: 1461, dpm: 0x055A, gy: 2039, gm:  1, gd: 26 },
-    { hy: 1462, dpm: 0x0B55, gy: 2040, gm:  1, gd: 15 },
-    { hy: 1463, dpm: 0x06D2, gy: 2041, gm:  1, gd: 4  },
-    { hy: 1464, dpm: 0x0EA5, gy: 2041, gm: 12, gd: 24 },
-    { hy: 1465, dpm: 0x0E4A, gy: 2042, gm: 12, gd: 14 },
-    { hy: 1466, dpm: 0x0A95, gy: 2043, gm: 12, gd: 3  },
-    { hy: 1467, dpm: 0x052D, gy: 2044, gm: 11, gd: 21 },
-    { hy: 1468, dpm: 0x0AAD, gy: 2045, gm: 11, gd: 10 },
-    { hy: 1469, dpm: 0x036C, gy: 2046, gm: 10, gd: 31 },
-    { hy: 1470, dpm: 0x0759, gy: 2047, gm: 10, gd: 20 },
-    { hy: 1471, dpm: 0x06D2, gy: 2048, gm: 10, gd: 9  },
-    { hy: 1472, dpm: 0x0695, gy: 2049, gm:  9, gd: 28 },
-    { hy: 1473, dpm: 0x052D, gy: 2050, gm:  9, gd: 17 },
-    { hy: 1474, dpm: 0x0A5B, gy: 2051, gm:  9, gd: 6  },
-    { hy: 1475, dpm: 0x04BA, gy: 2052, gm:  8, gd: 26 },
-    { hy: 1476, dpm: 0x09BA, gy: 2053, gm:  8, gd: 15 },
-    { hy: 1477, dpm: 0x03B4, gy: 2054, gm:  8, gd: 5  },
-    { hy: 1478, dpm: 0x0B69, gy: 2055, gm:  7, gd: 25 },
-    { hy: 1479, dpm: 0x0B52, gy: 2056, gm:  7, gd: 14 },
-    { hy: 1480, dpm: 0x0AA6, gy: 2057, gm:  7, gd: 3  },
-    { hy: 1481, dpm: 0x04B6, gy: 2058, gm:  6, gd: 22 },
-    { hy: 1482, dpm: 0x096D, gy: 2059, gm:  6, gd: 11 },
-    { hy: 1483, dpm: 0x02EC, gy: 2060, gm:  5, gd: 31 },
-    { hy: 1484, dpm: 0x06D9, gy: 2061, gm:  5, gd: 20 },
-    { hy: 1485, dpm: 0x0EB2, gy: 2062, gm:  5, gd: 10 },
-    { hy: 1486, dpm: 0x0D54, gy: 2063, gm:  4, gd: 30 },
-    { hy: 1487, dpm: 0x0D2A, gy: 2064, gm:  4, gd: 18 },
-    { hy: 1488, dpm: 0x0A56, gy: 2065, gm:  4, gd: 7  },
-    { hy: 1489, dpm: 0x04AE, gy: 2066, gm:  3, gd: 27 },
-    { hy: 1490, dpm: 0x096D, gy: 2067, gm:  3, gd: 16 },
-    { hy: 1491, dpm: 0x0D6A, gy: 2068, gm:  3, gd: 5  },
-    { hy: 1492, dpm: 0x0B54, gy: 2069, gm:  2, gd: 23 },
-    { hy: 1493, dpm: 0x0B29, gy: 2070, gm:  2, gd: 12 },
-    { hy: 1494, dpm: 0x0A93, gy: 2071, gm:  2, gd: 1  },
-    { hy: 1495, dpm: 0x052B, gy: 2072, gm:  1, gd: 21 },
-    { hy: 1496, dpm: 0x0A57, gy: 2073, gm:  1, gd: 9  },
-    { hy: 1497, dpm: 0x0536, gy: 2073, gm: 12, gd: 30 },
-    { hy: 1498, dpm: 0x0AB5, gy: 2074, gm: 12, gd: 19 },
-    { hy: 1499, dpm: 0x06AA, gy: 2075, gm: 12, gd: 9  },
-    { hy: 1500, dpm: 0x0E93, gy: 2076, gm: 11, gd: 27 },
-    { hy: 1501, dpm:      0, gy: 2077, gm: 11, gd: 17 }];
+// hDates.ts — re-exports from hijri-core; table is maintained in the core package
+export { hDatesTable } from 'hijri-core';
+export type { HijriYearRecord } from 'hijri-core';

src/hMonths.ts

@@ -1,46 +1,2 @@
-// hMonths.ts
-// Hijri Month Names
-export const hmLong = [
-    "Muharram",      // 1st month
-    "Safar",         // 2nd month
-    "Rabi'l Awwal",  // 3rd month
-    "Rabi'l Thani",  // 4th month
-    "Jumadal Awwal", // 5th month
-    "Jumadal Thani", // 6th month
-    "Rajab",         // 7th month
-    "Sha'ban",       // 8th month
-    "Ramadan",       // 9th month
-    "Shawwal",       // 10th month
-    "Dhul Qi'dah",   // 11th month
-    "Dhul Hijjah"    // 12th month
-];
-
-export const hmMedium = [
-    "Muharram",
-    "Safar",
-    "Rabi1",
-    "Rabi2",
-    "Jumada1",
-    "Jumada2",
-    "Rajab",
-    "Shaban",
-    "Ramadan",
-    "Shawwal",
-    "Dhul-Qidah",
-    "Dhul-Hijah"
-];
-
-export const hmShort = [
-    "Muh",
-    "Saf",
-    "Ra1",
-    "Ra2",
-    "Ju1",
-    "Ju2",
-    "Raj",
-    "Shb",
-    "Ram",
-    "Shw",
-    "DhQ",
-    "DhH"
-];
+// hMonths.ts — re-exports from hijri-core
+export { hmLong, hmMedium, hmShort } from 'hijri-core';

src/hWeekdays.ts

@@ -1,25 +1,2 @@
-// hWeekdays.ts
-// Full names of Hijri weekdays
-export const hwLong = [
-    "Yawm al-Ahad",    // Sunday
-    "Yawm al-Ithnayn", // Monday
-    "Yawm ath-Thulatha'",  // Tuesday
-    "Yawm al-Arba`a'",     // Wednesday
-    "Yawm al-Khamis",  // Thursday
-    "Yawm al-Jum`a",   // Friday
-    "Yawm as-Sabt"     // Saturday
-];
-
-// Abbreviated names of Hijri weekdays
-export const hwShort = [
-    "Ahad",   // Sunday
-    "Ithn",   // Monday
-    "Thul",   // Tuesday
-    "Arba",   // Wednesday
-    "Kham",   // Thursday
-    "Jum`a",  // Friday
-    "Sabt"    // Saturday
-];
-
-// Numeric representation of Hijri weekdays (1 for Sunday, 2 for Monday, etc.)
-export const hwNumeric = [1, 2, 3, 4, 5, 6, 7];
+// hWeekdays.ts — re-exports from hijri-core
+export { hwLong, hwShort, hwNumeric } from 'hijri-core';

src/toGregorian.ts

@@ -1,50 +1,9 @@
-// toGregorian.ts
-import { DateTime } from 'luxon';
-import { hDatesTable } from './hDates';
-import { fcnaToGregorian } from './fcna';
-import { isValidHijriDate } from './utils';
+// toGregorian.ts — thin wrapper over hijri-core; preserves throw-on-invalid behavior
+import { toGregorian as coreToGregorian } from 'hijri-core';
 import type { ConversionOptions } from './types';
 
 export function toGregorian(hy: number, hm: number, hd: number, options?: ConversionOptions): Date | null {
-  if (options?.calendar === 'fcna') {
-    const result = fcnaToGregorian(hy, hm, hd);
-    if (result === null) throw new Error('Invalid Hijri date');
-    return result;
-  }
-
-  if (!isValidHijriDate(hy, hm, hd)) {
-    throw new Error('Invalid Hijri date');
-  }
-
-  // Binary search on hy (table is sorted ascending by Hijri year).
-  let lo = 0;
-  let hi = hDatesTable.length - 1;
-  let found = -1;
-
-  while (lo <= hi) {
-    const mid = (lo + hi) >>> 1;
-    const midHy = hDatesTable[mid].hy;
-
-    if (midHy === hy) {
-      found = mid;
-      break;
-    } else if (midHy < hy) {
-      lo = mid + 1;
-    } else {
-      hi = mid - 1;
-    }
-  }
-
-  if (found === -1) return null;
-
-  const record = hDatesTable[found];
-  let totalDays = 0;
-
-  for (let i = 0; i < hm - 1; i++) {
-    totalDays += (record.dpm >> i) & 1 ? 30 : 29;
-  }
-  totalDays += hd - 1;
-
-  const startDate = DateTime.utc(record.gy, record.gm, record.gd);
-  return startDate.plus({ days: totalDays }).toJSDate();
+  const result = coreToGregorian(hy, hm, hd, options);
+  if (result === null) throw new Error('Invalid Hijri date');
+  return result;
 }

src/toHijri.ts

@@ -1,62 +1,2 @@
-// toHijri.ts
-import { hDatesTable } from './hDates';
-import { fcnaToHijri } from './fcna';
-import type { HijriDate, HijriYearRecord, ConversionOptions } from './types';
-
-export function toHijri(gregorianDate: Date, options?: ConversionOptions): HijriDate | null {
-  if (options?.calendar === 'fcna') {
-    return fcnaToHijri(gregorianDate);
-  }
-
-  if (!(gregorianDate instanceof Date) || isNaN(gregorianDate.getTime())) {
-    throw new Error('Invalid Gregorian date');
-  }
-
-  // Normalize input to UTC midnight so comparisons are timezone-independent.
-  const inputUtc = Date.UTC(
-    gregorianDate.getFullYear(),
-    gregorianDate.getMonth(),
-    gregorianDate.getDate(),
-  );
-
-  // Binary search: find the last table entry whose Gregorian date <= input.
-  // Table is sorted ascending by (gy, gm, gd).
-  let lo = 0;
-  let hi = hDatesTable.length - 1;
-  let found = -1;
-
-  while (lo <= hi) {
-    const mid = (lo + hi) >>> 1;
-    const entry = hDatesTable[mid];
-    const entryUtc = Date.UTC(entry.gy, entry.gm - 1, entry.gd);
-
-    if (entryUtc <= inputUtc) {
-      found = mid;
-      lo = mid + 1;
-    } else {
-      hi = mid - 1;
-    }
-  }
-
-  // dpm === 0 means sentinel entry (marks end-of-table boundary, not a real year).
-  if (found === -1 || hDatesTable[found].dpm === 0) return null;
-
-  const record: HijriYearRecord = hDatesTable[found];
-  const startUtc = Date.UTC(record.gy, record.gm - 1, record.gd);
-  let remainingDays = Math.round((inputUtc - startUtc) / 86_400_000);
-  let hijriMonth = 0;
-
-  for (let i = 0; i < 12; i++) {
-    const daysInThisMonth = (record.dpm >> i) & 1 ? 30 : 29;
-    if (remainingDays < daysInThisMonth) {
-      hijriMonth = i + 1;
-      break;
-    }
-    remainingDays -= daysInThisMonth;
-  }
-
-  // hijriMonth remains 0 if the date falls beyond the last table entry's year.
-  if (hijriMonth === 0) return null;
-
-  return { hy: record.hy, hm: hijriMonth, hd: remainingDays + 1 };
-}
+// toHijri.ts — delegates to hijri-core
+export { toHijri } from 'hijri-core';

src/types.ts

@@ -1,23 +1,6 @@
-// types.ts
-export interface HijriDate {
-  hy: number; // Hijri year
-  hm: number; // Hijri month (1–12)
-  hd: number; // Hijri day (1–30)
-}
+// types.ts — re-exports from hijri-core for backward compatibility
+export type { HijriDate, HijriYearRecord, ConversionOptions } from 'hijri-core';
 
-export interface HijriYearRecord {
-  hy:  number; // Hijri year
-  dpm: number; // days-per-month bitmask (bit 0 = month 1: 1→30 days, 0→29 days)
-  gy:  number; // Gregorian year of 1 Muharram
-  gm:  number; // Gregorian month of 1 Muharram
-  gd:  number; // Gregorian day of 1 Muharram
-}
-
-// Calendar system selector.
-// 'uaq' — Umm al-Qura (default): table-based, covers 1318–1500 H.
-// 'fcna' — FCNA/ISNA: astronomical calculation, works for all Hijri years.
+// CalendarSystem documents the built-in calendar identifiers.
+// hijri-core accepts any string via registerCalendar(); this type covers the defaults.
 export type CalendarSystem = 'uaq' | 'fcna';
-
-export interface ConversionOptions {
-  calendar?: CalendarSystem;
-}

src/utils.ts

@@ -1,37 +1,2 @@
-// utils.ts
-import { hDatesTable } from './hDates';
-import { fcnaIsValid } from './fcna';
-import type { ConversionOptions } from './types';
-
-export function isValidHijriDate(hy: number, hm: number, hd: number, options?: ConversionOptions): boolean {
-  if (options?.calendar === 'fcna') {
-    return fcnaIsValid(hy, hm, hd);
-  }
-
-  // Binary search on hy.
-  let lo = 0;
-  let hi = hDatesTable.length - 1;
-  let found = -1;
-
-  while (lo <= hi) {
-    const mid = (lo + hi) >>> 1;
-    const midHy = hDatesTable[mid].hy;
-
-    if (midHy === hy) {
-      found = mid;
-      break;
-    } else if (midHy < hy) {
-      lo = mid + 1;
-    } else {
-      hi = mid - 1;
-    }
-  }
-
-  // dpm === 0 means sentinel entry (marks end-of-table boundary, not a real year).
-  if (found === -1 || hDatesTable[found].dpm === 0) return false;
-
-  const record = hDatesTable[found];
-  if (hm < 1 || hm > 12 || hd < 1) return false;
-  const daysInMonth = (record.dpm >> (hm - 1)) & 1 ? 30 : 29;
-  return hd <= daysInMonth;
-}
+// utils.ts — delegates to hijri-core
+export { isValidHijriDate } from 'hijri-core';

tsup.config.ts

@@ -10,7 +10,7 @@ export default defineConfig({
   sourcemap: true,
   target: 'es2020',
   platform: 'node',
-  external: ['luxon'],
+  external: ['luxon', 'hijri-core'],
   outExtension({ format }) {
     return { js: format === 'cjs' ? '.cjs' : '.mjs' };
   },