diff --git a/.prettierrc b/.prettierrc
deleted file mode 100644
index 383f607..0000000
--- a/.prettierrc
+++ /dev/null
@@ -1,6 +0,0 @@
-{
-  "singleQuote": true,
-  "trailingComma": "all",
-  "printWidth": 100,
-  "tabWidth": 2
-}
diff --git a/eslint.config.mjs b/eslint.config.mjs
index f4be42a..ba1683f 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -1,10 +1,16 @@
-import js from '@eslint/js';
-import tseslint from 'typescript-eslint';
-import prettier from 'eslint-config-prettier';
+import tsParser from '@typescript-eslint/parser';
+import tsPlugin from '@typescript-eslint/eslint-plugin';
+import eslintConfigPrettier from 'eslint-config-prettier';
+import { typescript } from '@acamarata/eslint-config';
 
-export default tseslint.config(
-  { ignores: ['dist/', 'node_modules/', '*.cjs', '*.mjs'] },
-  js.configs.recommended,
-  ...tseslint.configs.recommended,
-  prettier,
-);
+export default [
+  {
+    plugins: { '@typescript-eslint': tsPlugin },
+    languageOptions: { parser: tsParser },
+  },
+  ...typescript,
+  eslintConfigPrettier,
+  {
+    ignores: ['dist/', 'node_modules/', '*.cjs', '*.mjs'],
+  },
+];
diff --git a/package.json b/package.json
index 7738514..9d7b4a6 100644
--- a/package.json
+++ b/package.json
@@ -66,13 +66,16 @@
     }
   },
   "devDependencies": {
+    "@acamarata/eslint-config": "^0.1.0",
+    "@acamarata/prettier-config": "^0.1.0",
+    "@acamarata/tsconfig": "^0.1.0",
     "@eslint/js": "^10.0.1",
     "@types/luxon": "^3.4.2",
-    "hijri-core": "^1.0.0",
-    "luxon": "^3.5.0",
     "@types/node": "^22.15.0",
     "eslint": "^10.0.3",
     "eslint-config-prettier": "^10.1.8",
+    "hijri-core": "^1.0.0",
+    "luxon": "^3.5.0",
     "prettier": "^3.8.1",
     "tsup": "^8.0.0",
     "typescript": "^5.5.0",
@@ -90,5 +93,6 @@
   "bugs": {
     "url": "https://github.com/acamarata/luxon-hijri/issues"
   },
-  "type": "module"
+  "type": "module",
+  "prettier": "@acamarata/prettier-config"
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 2159303..8145deb 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -8,6 +8,15 @@ importers:
 
   .:
     devDependencies:
+      '@acamarata/eslint-config':
+        specifier: ^0.1.0
+        version: 0.1.0(@typescript-eslint/eslint-plugin@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@8.56.1(eslint@10.0.3)(typescript@5.9.3))(eslint-config-prettier@10.1.8(eslint@10.0.3))(eslint@10.0.3)
+      '@acamarata/prettier-config':
+        specifier: ^0.1.0
+        version: 0.1.0(prettier@3.8.1)
+      '@acamarata/tsconfig':
+        specifier: ^0.1.0
+        version: 0.1.0
       '@eslint/js':
         specifier: ^10.0.1
         version: 10.0.1(eslint@10.0.3)
@@ -44,6 +53,32 @@ importers:
 
 packages:
 
+  '@acamarata/eslint-config@0.1.0':
+    resolution: {integrity: sha512-St2TObpHKXBLBy1GPrXWlHzXCujJ7jaor6BuWRdLMTOjM56LPBDJx+898R7yFyI8Wi52VWNZdSTPxzHuyRAq+A==}
+    engines: {node: '>=20'}
+    peerDependencies:
+      '@typescript-eslint/eslint-plugin': '>=8.0.0'
+      '@typescript-eslint/parser': '>=8.0.0'
+      eslint: '>=9.0.0'
+      eslint-config-prettier: '>=9.0.0'
+      eslint-plugin-react: '>=7.0.0'
+      eslint-plugin-react-hooks: '>=5.0.0'
+    peerDependenciesMeta:
+      eslint-plugin-react:
+        optional: true
+      eslint-plugin-react-hooks:
+        optional: true
+
+  '@acamarata/prettier-config@0.1.0':
+    resolution: {integrity: sha512-ImMnz/653ettR4gJVd1f7Pz61DQSeDmUtguLrnCl8RdYncqfghT+QGEO5Znml0KvgX3vk4c4roPAWYdXaZgcPA==}
+    engines: {node: '>=20'}
+    peerDependencies:
+      prettier: '>=3.0.0'
+
+  '@acamarata/tsconfig@0.1.0':
+    resolution: {integrity: sha512-bgzyBak43mE+0HhduZX3cvaPjKcggtGGZZMjr35qtYWolsIWgZ9nx7OOswbVYoU35qoUv6rZ0mTK6GbZ8QTYjw==}
+    engines: {node: '>=20'}
+
   '@esbuild/aix-ppc64@0.27.3':
     resolution: {integrity: sha512-9fJMTNFTWZMh5qwrBItuziu834eOCUcEqymSH7pY+zoMVEZg3gcPuBNxH1EvfVYe9h0x/Ptw8KBzv7qxb7l8dg==}
     engines: {node: '>=18'}
@@ -925,6 +960,19 @@ packages:
 
 snapshots:
 
+  '@acamarata/eslint-config@0.1.0(@typescript-eslint/eslint-plugin@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@8.56.1(eslint@10.0.3)(typescript@5.9.3))(eslint-config-prettier@10.1.8(eslint@10.0.3))(eslint@10.0.3)':
+    dependencies:
+      '@typescript-eslint/eslint-plugin': 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': 8.56.1(eslint@10.0.3)(typescript@5.9.3)
+      eslint: 10.0.3
+      eslint-config-prettier: 10.1.8(eslint@10.0.3)
+
+  '@acamarata/prettier-config@0.1.0(prettier@3.8.1)':
+    dependencies:
+      prettier: 3.8.1
+
+  '@acamarata/tsconfig@0.1.0': {}
+
   '@esbuild/aix-ppc64@0.27.3':
     optional: true
 
diff --git a/src/formatHijriDate.ts b/src/formatHijriDate.ts
index e9d3e9a..851a160 100644
--- a/src/formatHijriDate.ts
+++ b/src/formatHijriDate.ts
@@ -38,7 +38,7 @@ export function formatHijriDate(hijriDate: HijriDate, format: string): string {
     return _gregDt;
   }
 
-  return format.replace(TOKEN_RE, (match) => {
+  return format.replace(TOKEN_RE, (match): string => {
     switch (match) {
       case 'iYYYY':
         return String(hijriDate.hy).padStart(4, '0');
@@ -49,9 +49,12 @@ export function formatHijriDate(hijriDate: HijriDate, format: string): string {
       case 'iM':
         return String(hijriDate.hm);
       case 'iMMM':
-        return hmMedium[hijriDate.hm - 1];
+        // 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':
-        return hmLong[hijriDate.hm - 1];
+        // 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':
@@ -62,9 +65,13 @@ export function formatHijriDate(hijriDate: HijriDate, format: string): string {
         // 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;
-        if (match === 'iE') return String(hwNumeric[idx]);
-        if (match === 'iEEE') return hwShort[idx];
-        return hwLong[idx];
+        // 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]!);
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        if (match === 'iEEE') return hwShort[idx]!;
+        // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
+        return hwLong[idx]!;
       }
       case 'iooo':
       case 'ioooo':
diff --git a/tsconfig.json b/tsconfig.json
index 035eb39..76b5a64 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,18 +1,10 @@
 {
+  "extends": "@acamarata/tsconfig/tsconfig.library.json",
   "compilerOptions": {
-    "target": "ES2020",
-    "module": "ESNext",
-    "moduleResolution": "bundler",
-    "strict": true,
-    "esModuleInterop": true,
-    "declaration": true,
-    "declarationMap": true,
-    "sourceMap": true,
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
-    "outDir": "dist",
+    "esModuleInterop": true,
     "rootDir": "src",
-    "forceConsistentCasingInFileNames": true,
     "types": ["node"]
   },
   "include": ["src/**/*"],