diff --git a/eslint.config.mjs b/eslint.config.mjs
index ba1683f..88a9226 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -6,11 +6,18 @@ import { typescript } from '@acamarata/eslint-config';
 export default [
   {
     plugins: { '@typescript-eslint': tsPlugin },
-    languageOptions: { parser: tsParser },
+    languageOptions: {
+      parser: tsParser,
+      parserOptions: {
+        project: true,
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+    files: ['src/**/*.ts'],
   },
-  ...typescript,
+  ...typescript.map((config) => ({ ...config, files: ['src/**/*.ts'] })),
   eslintConfigPrettier,
   {
-    ignores: ['dist/', 'node_modules/', '*.cjs', '*.mjs'],
+    ignores: ['dist/', 'node_modules/', 'coverage/', 'test.mjs', 'test-cjs.cjs', 'test-crossval.mjs', 'tsup.config.ts', 'typedoc.json'],
   },
 ];
diff --git a/package.json b/package.json
index be6bc17..119cc2a 100644
--- a/package.json
+++ b/package.json
@@ -73,6 +73,9 @@
     "@eslint/js": "^10.0.1",
     "@types/luxon": "^3.4.2",
     "@types/node": "^22.15.0",
+    "@typescript-eslint/eslint-plugin": "^8.56.1",
+    "@typescript-eslint/parser": "^8.56.1",
+    "c8": "^10.1.2",
     "eslint": "^10.0.3",
     "eslint-config-prettier": "^10.1.8",
     "hijri-core": "^1.0.0",
@@ -82,8 +85,7 @@
     "typedoc": "^0.28.19",
     "typedoc-plugin-markdown": "^4.11.0",
     "typescript": "^5.5.0",
-    "typescript-eslint": "^8.56.1",
-    "c8": "^10.1.2"
+    "typescript-eslint": "^8.56.1"
   },
   "publishConfig": {
     "access": "public",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 7a7e5a8..cfa7af3 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -26,6 +26,12 @@ importers:
       '@types/node':
         specifier: ^22.15.0
         version: 22.15.0
+      '@typescript-eslint/eslint-plugin':
+        specifier: ^8.56.1
+        version: 8.56.1(@typescript-eslint/parser@8.56.1(eslint@10.0.3)(typescript@5.9.3))(eslint@10.0.3)(typescript@5.9.3)
+      '@typescript-eslint/parser':
+        specifier: ^8.56.1
+        version: 8.56.1(eslint@10.0.3)(typescript@5.9.3)
       c8:
         specifier: ^10.1.2
         version: 10.1.3
diff --git a/src/formatHijriDate.ts b/src/formatHijriDate.ts
index 851a160..2f6d427 100644
--- a/src/formatHijriDate.ts
+++ b/src/formatHijriDate.ts
@@ -1,9 +1,9 @@
 // formatHijriDate.ts
-import { DateTime } from 'luxon';
-import { hmLong, hmMedium } from './hMonths';
-import { hwLong, hwShort, hwNumeric } from './hWeekdays';
-import { toGregorian } from './toGregorian';
-import type { HijriDate } from './types';
+import { DateTime } from "luxon";
+import { hmLong, hmMedium } from "./hMonths";
+import { hwLong, hwShort, hwNumeric } from "./hWeekdays";
+import { toGregorian } from "./toGregorian";
+import type { HijriDate } from "./types";
 
 // Token regex: longest tokens first to prevent partial matches.
 const TOKEN_RE =
@@ -33,49 +33,49 @@ export function formatHijriDate(hijriDate: HijriDate, format: string): string {
   function getGregDt(): DateTime {
     if (!_gregDt) {
       const greg = toGregorian(hijriDate.hy, hijriDate.hm, hijriDate.hd);
-      _gregDt = DateTime.fromJSDate(greg, { zone: 'UTC' });
+      _gregDt = DateTime.fromJSDate(greg, { zone: "UTC" });
     }
     return _gregDt;
   }
 
   return format.replace(TOKEN_RE, (match): string => {
     switch (match) {
-      case 'iYYYY':
-        return String(hijriDate.hy).padStart(4, '0');
-      case 'iYY':
-        return String(hijriDate.hy % 100).padStart(2, '0');
-      case 'iMM':
-        return String(hijriDate.hm).padStart(2, '0');
-      case 'iM':
+      case "iYYYY":
+        return String(hijriDate.hy).padStart(4, "0");
+      case "iYY":
+        return String(hijriDate.hy % 100).padStart(2, "0");
+      case "iMM":
+        return String(hijriDate.hm).padStart(2, "0");
+      case "iM":
         return String(hijriDate.hm);
-      case 'iMMM':
+      case "iMMM":
         // Non-null: hm is validated 1-12 above; index hm-1 is always 0-11, within array bounds.
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         return hmMedium[hijriDate.hm - 1]!;
-      case 'iMMMM':
+      case "iMMMM":
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         return hmLong[hijriDate.hm - 1]!;
-      case 'iDD':
-        return String(hijriDate.hd).padStart(2, '0');
-      case 'iD':
+      case "iDD":
+        return String(hijriDate.hd).padStart(2, "0");
+      case "iD":
         return String(hijriDate.hd);
-      case 'iE':
-      case 'iEEE':
-      case 'iEEEE': {
+      case "iE":
+      case "iEEE":
+      case "iEEEE": {
         // Luxon weekday: 1=Mon … 7=Sun. Modulo 7: Mon=1 … Sat=6, Sun=0.
         // hwLong/hwShort/hwNumeric arrays: index 0=Sunday, 1=Monday, … 6=Saturday.
         const idx = getGregDt().weekday % 7;
         // Non-null: idx is always 0-6 (weekday%7), within all hw* array bounds.
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        if (match === 'iE') return String(hwNumeric[idx]!);
+        if (match === "iE") return String(hwNumeric[idx]!);
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
-        if (match === 'iEEE') return hwShort[idx]!;
+        if (match === "iEEE") return hwShort[idx]!;
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         return hwLong[idx]!;
       }
-      case 'iooo':
-      case 'ioooo':
-        return 'AH';
+      case "iooo":
+      case "ioooo":
+        return "AH";
       default:
         // Delegate time and timezone tokens to Luxon using the Gregorian DateTime.
         return getGregDt().toFormat(match);
diff --git a/src/formatPatterns.ts b/src/formatPatterns.ts
index 3351414..36e6f88 100644
--- a/src/formatPatterns.ts
+++ b/src/formatPatterns.ts
@@ -9,46 +9,46 @@
 // Define a mapping of Hijri format tokens to their meanings
 export const formatPatterns = {
   // Hijri Year
-  iYYYY: 'Hijri year (4 digits)',
-  iYY: 'Hijri year (2 digits)',
+  iYYYY: "Hijri year (4 digits)",
+  iYY: "Hijri year (2 digits)",
 
   // Hijri Month
-  iMM: 'Hijri month (2 digits, zero-padded)',
-  iM: 'Hijri month (1 or 2 digits without zero-padding)',
-  iMMM: 'Hijri month (abbreviated name)',
-  iMMMM: 'Hijri month (full name)',
+  iMM: "Hijri month (2 digits, zero-padded)",
+  iM: "Hijri month (1 or 2 digits without zero-padding)",
+  iMMM: "Hijri month (abbreviated name)",
+  iMMMM: "Hijri month (full name)",
 
   // Hijri Day
-  iDD: 'Hijri day of the month (2 digits, zero-padded)',
-  iD: 'Hijri day of the month (1 or 2 digits without zero-padding)',
+  iDD: "Hijri day of the month (2 digits, zero-padded)",
+  iD: "Hijri day of the month (1 or 2 digits without zero-padding)",
 
   // Hijri Weekday
-  iE: 'Hijri weekday (1 digit)',
-  iEEE: 'Hijri weekday (abbreviated name)',
-  iEEEE: 'Hijri weekday (full name)',
+  iE: "Hijri weekday (1 digit)",
+  iEEE: "Hijri weekday (abbreviated name)",
+  iEEEE: "Hijri weekday (full name)",
 
   // Hour, Minute, Second
   // These can remain the same as in Gregorian as they don’t change in Hijri
-  HH: 'Hour (2 digits, zero-padded, 24-hour clock)',
-  H: 'Hour (1 or 2 digits without zero-padding, 24-hour clock)',
-  hh: 'Hour (2 digits, zero-padded, 12-hour clock)',
-  h: 'Hour (1 or 2 digits without zero-padding, 12-hour clock)',
-  mm: 'Minute (2 digits, zero-padded)',
-  m: 'Minute (1 or 2 digits without zero-padding)',
-  ss: 'Second (2 digits, zero-padded)',
-  s: 'Second (1 or 2 digits without zero-padding)',
+  HH: "Hour (2 digits, zero-padded, 24-hour clock)",
+  H: "Hour (1 or 2 digits without zero-padding, 24-hour clock)",
+  hh: "Hour (2 digits, zero-padded, 12-hour clock)",
+  h: "Hour (1 or 2 digits without zero-padding, 12-hour clock)",
+  mm: "Minute (2 digits, zero-padded)",
+  m: "Minute (1 or 2 digits without zero-padding)",
+  ss: "Second (2 digits, zero-padded)",
+  s: "Second (1 or 2 digits without zero-padding)",
 
   // AM/PM
-  a: 'AM/PM marker',
+  a: "AM/PM marker",
 
   // Other
-  iooo: 'Hijri era (abbreviated)',
-  ioooo: 'Hijri era (full)',
+  iooo: "Hijri era (abbreviated)",
+  ioooo: "Hijri era (full)",
 
   // Timezone
-  z: 'Timezone (abbreviated)',
-  zz: 'Timezone (medium)',
-  zzz: 'Timezone (full)',
-  Z: 'Timezone offset from UTC (+HH:MM)',
-  ZZ: 'Timezone offset from UTC (condensed)',
+  z: "Timezone (abbreviated)",
+  zz: "Timezone (medium)",
+  zzz: "Timezone (full)",
+  Z: "Timezone offset from UTC (+HH:MM)",
+  ZZ: "Timezone offset from UTC (condensed)",
 };
diff --git a/src/hDates.ts b/src/hDates.ts
index e9c9d5d..af19eb0 100644
--- a/src/hDates.ts
+++ b/src/hDates.ts
@@ -6,5 +6,5 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // 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';
+export { hDatesTable } from "hijri-core";
+export type { HijriYearRecord } from "hijri-core";
diff --git a/src/hMonths.ts b/src/hMonths.ts
index b03c3c8..a7da14a 100644
--- a/src/hMonths.ts
+++ b/src/hMonths.ts
@@ -6,4 +6,4 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // hMonths.ts: re-exports from hijri-core
-export { hmLong, hmMedium, hmShort } from 'hijri-core';
+export { hmLong, hmMedium, hmShort } from "hijri-core";
diff --git a/src/hWeekdays.ts b/src/hWeekdays.ts
index cd07c32..8b8ad2d 100644
--- a/src/hWeekdays.ts
+++ b/src/hWeekdays.ts
@@ -6,4 +6,4 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // hWeekdays.ts: re-exports from hijri-core
-export { hwLong, hwShort, hwNumeric } from 'hijri-core';
+export { hwLong, hwShort, hwNumeric } from "hijri-core";
diff --git a/src/index.ts b/src/index.ts
index f0d00f8..9d86a26 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,11 +1,11 @@
 // index.ts
-export { formatPatterns } from './formatPatterns';
-export { hDatesTable } from './hDates';
-export type { HijriYearRecord } from './hDates';
-export { hmLong, hmMedium, hmShort } from './hMonths';
-export { hwLong, hwShort, hwNumeric } from './hWeekdays';
-export { toGregorian } from './toGregorian';
-export { toHijri } from './toHijri';
-export { formatHijriDate } from './formatHijriDate';
-export { isValidHijriDate } from './utils';
-export type { HijriDate, CalendarSystem, ConversionOptions } from './types';
+export { formatPatterns } from "./formatPatterns";
+export { hDatesTable } from "./hDates";
+export type { HijriYearRecord } from "./hDates";
+export { hmLong, hmMedium, hmShort } from "./hMonths";
+export { hwLong, hwShort, hwNumeric } from "./hWeekdays";
+export { toGregorian } from "./toGregorian";
+export { toHijri } from "./toHijri";
+export { formatHijriDate } from "./formatHijriDate";
+export { isValidHijriDate } from "./utils";
+export type { HijriDate, CalendarSystem, ConversionOptions } from "./types";
diff --git a/src/toGregorian.ts b/src/toGregorian.ts
index ec53c89..091b0e6 100644
--- a/src/toGregorian.ts
+++ b/src/toGregorian.ts
@@ -6,8 +6,8 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // toGregorian.ts: thin wrapper over hijri-core; preserves throw-on-invalid behavior
-import { toGregorian as coreToGregorian } from 'hijri-core';
-import type { ConversionOptions } from './types';
+import { toGregorian as coreToGregorian } from "hijri-core";
+import type { ConversionOptions } from "./types";
 
 /**
  * Convert a Hijri date to a Gregorian Date object.
@@ -24,6 +24,6 @@ import type { ConversionOptions } from './types';
  */
 export function toGregorian(hy: number, hm: number, hd: number, options?: ConversionOptions): Date {
   const result = coreToGregorian(hy, hm, hd, options);
-  if (result === null) throw new Error('Invalid Hijri date');
+  if (result === null) throw new Error("Invalid Hijri date");
   return result;
 }
diff --git a/src/toHijri.ts b/src/toHijri.ts
index 04acb90..fb9d067 100644
--- a/src/toHijri.ts
+++ b/src/toHijri.ts
@@ -6,4 +6,4 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // toHijri.ts: delegates to hijri-core
-export { toHijri } from 'hijri-core';
+export { toHijri } from "hijri-core";
diff --git a/src/types.ts b/src/types.ts
index b988bd3..f178cee 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -6,7 +6,7 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // types.ts: re-exports from hijri-core for backward compatibility
-export type { HijriDate, HijriYearRecord, ConversionOptions } from 'hijri-core';
+export type { HijriDate, HijriYearRecord, ConversionOptions } from "hijri-core";
 
 /**
  * Built-in calendar system identifiers.
@@ -17,4 +17,4 @@ export type { HijriDate, HijriYearRecord, ConversionOptions } from 'hijri-core';
  * hijri-core accepts any string identifier via `registerCalendar()`. This type covers
  * the built-in defaults only.
  */
-export type CalendarSystem = 'uaq' | 'fcna';
+export type CalendarSystem = "uaq" | "fcna";
diff --git a/src/utils.ts b/src/utils.ts
index f82fbf0..5e26588 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -6,4 +6,4 @@
  * SPORT: packages.md — luxon-hijri row
  */
 // utils.ts: delegates to hijri-core
-export { isValidHijriDate } from 'hijri-core';
+export { isValidHijriDate } from "hijri-core";