chore: strengthen backend eslint profile

eslint.config.mjs

@@ -1,31 +1,71 @@
 // @ts-check
+import nest from '@darraghor/eslint-plugin-nestjs-typed';
 import eslint from '@eslint/js';
-import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended';
+import stylistic from '@stylistic/eslint-plugin';
+import { createTypeScriptImportResolver } from 'eslint-import-resolver-typescript';
+import { importX } from 'eslint-plugin-import-x';
+import jest from 'eslint-plugin-jest';
+import node from 'eslint-plugin-n';
+import perfectionist from 'eslint-plugin-perfectionist';
+import regexp from 'eslint-plugin-regexp';
+import security from 'eslint-plugin-security';
+import sonarjs from 'eslint-plugin-sonarjs';
+import { defineConfig, globalIgnores } from 'eslint/config';
 import globals from 'globals';
 import tseslint from 'typescript-eslint';
 
-export default tseslint.config(
+const tests = ['**/*.spec.ts', 'test/**/*.ts'];
+
+export default defineConfig(
+  globalIgnores(['dist/**', 'dist-dev/**', 'build/**', 'generated/**', 'coverage/**', 'node_modules/**']),
   {
-    ignores: ['eslint.config.mjs', 'dist/', 'generated/'],
-  },
-  eslint.configs.recommended,
-  ...tseslint.configs.recommendedTypeChecked,
-  eslintPluginPrettierRecommended,
-  {
-    languageOptions: {
-      globals: {
-        ...globals.node,
-        ...globals.jest,
-      },
-      sourceType: 'commonjs',
-      parserOptions: {
-        projectService: true,
-        tsconfigRootDir: import.meta.dirname,
-      },
+    files: ['**/*.{ts,js,cjs,mjs}'],
+    extends: [
+      eslint.configs.recommended,
+      node.configs['flat/recommended'],
+      importX.flatConfigs.recommended,
+      sonarjs.configs.recommended,
+      regexp.configs['flat/recommended'],
+      security.configs.recommended,
+      perfectionist.configs['recommended-natural'],
+      stylistic.configs.customize({ indent: 2, quotes: 'single', semi: true, jsx: false }),
+    ],
+    languageOptions: { globals: globals.node },
+    linterOptions: { reportUnusedDisableDirectives: 'error' },
+    settings: {
+      'import-x/resolver-next': [createTypeScriptImportResolver()],
+      'node': { tryExtensions: ['.ts', '.js', '.json', '.node'], version: '24.21.0' },
+    },
+    rules: {
+      'curly': ['error', 'multi-line'],
+      // This private application is deployed as a whole, never published to npm.
+      'n/no-unpublished-import': 'off',
+      'n/no-unpublished-require': 'off',
+      // Decorator execution and object insertion order can be observable at runtime.
+      'perfectionist/sort-decorators': 'off',
+      'perfectionist/sort-objects': 'off',
+      'perfectionist/sort-modules': 'off',
+      'perfectionist/sort-classes': 'off',
+      '@stylistic/brace-style': ['error', '1tbs', { allowSingleLine: false }],
+      '@stylistic/arrow-parens': ['error', 'always'],
+      '@stylistic/operator-linebreak': ['error', 'after'],
+      'import-x/no-duplicates': ['error', { 'prefer-inline': true }],
     },
   },
   {
+    files: ['**/*.mjs'],
+    extends: [node.configs['flat/recommended-module']],
+  },
+  {
+    files: ['**/*.ts'],
+    extends: [tseslint.configs.recommendedTypeChecked, importX.flatConfigs.typescript],
+    languageOptions: {
+      sourceType: 'module',
+      parserOptions: { projectService: true, tsconfigRootDir: import.meta.dirname },
+    },
     rules: {
+      // TypeScript resolves source imports; import-x checks them with the TS resolver.
+      'n/no-missing-import': 'off',
       'no-magic-numbers': 'off',
       '@typescript-eslint/no-magic-numbers': [
         'error',
@@ -63,24 +103,28 @@ export default tseslint.config(
           enforceConst: true,
         },
       ],
-      '@typescript-eslint/no-explicit-any': 'off',
       '@typescript-eslint/no-non-null-assertion': 'error',
-      'no-restricted-syntax': [
-        'error',
-        {
-          selector:
-            'PropertyDefinition[definite=true], VariableDeclarator[definite=true]',
-          message:
-            'Definite assignment assertions are forbidden. Initialize owned values; use declare only for externally populated DTO fields.',
-        },
-      ],
-      '@typescript-eslint/no-floating-promises': 'warn',
-      '@typescript-eslint/no-unsafe-argument': 'warn',
-      'prettier/prettier': ['error', { endOfLine: 'auto' }],
+      'no-restricted-syntax': ['error', {
+        selector: 'PropertyDefinition[definite=true], VariableDeclarator[definite=true]',
+        message: 'Definite assignment assertions are forbidden. Initialize owned values; use declare only for externally populated DTO fields.',
+      }],
     },
   },
   {
-    files: ['**/*.spec.ts', 'test/**/*.ts'],
-    rules: { '@typescript-eslint/no-magic-numbers': 'off' },
+    files: ['src/**/*.ts'],
+    ignores: tests,
+    extends: [nest.configs.flatRecommended],
+    rules: {
+      // Domain string unions are validated with IsIn rather than runtime TS enums.
+      '@darraghor/nestjs-typed/validated-non-primitive-property-needs-type-decorator': ['error', { additionalTypeDecorators: ['IsIn'] }],
+    },
+  },
+  {
+    files: tests,
+    extends: [jest.configs['flat/recommended']],
+    rules: {
+      '@typescript-eslint/no-magic-numbers': 'off',
+      'jest/expect-expect': ['error', { assertFunctionNames: ['expect', '**.expect'] }],
+    },
   },
 );