feat(lint): migrate to ESLint 9 flat config

Replace .eslintrc.json and .eslintignore with a single
eslint.config.mjs using the new flat config format.

typescript-eslint v8 split ban-types into three rules:
- no-unsafe-function-type (for Function)
- no-wrapper-object-types (for Object, String, etc.)
- no-restricted-types (user-defined)

Update all inline eslint-disable directives to use the
new rule names. Fix one real Object -> object type issue
in transformerInterceptor.ts.

The old header/header plugin is gone; update 5 test files
to use the replacement headers/header-format directive.

Add *.fuzz.{js,ts} to the jest globals config, which the
old config covered via a global env setting.

Author: oetr

.eslintignore

@@ -0,0 +1,145 @@
+import js from "@eslint/js";
+import eslintConfigPrettier from "eslint-config-prettier";
+import headers from "eslint-plugin-headers";
+import importX from "eslint-plugin-import-x";
+import jest from "eslint-plugin-jest";
+import markdownlint from "eslint-plugin-markdownlint";
+import markdownlintParser from "eslint-plugin-markdownlint/parser.js";
+import globals from "globals";
+import tseslint from "typescript-eslint";
+
+export default tseslint.config(
+	// Global ignores (replaces .eslintignore)
+	{
+		ignores: [
+			"**/dist/",
+			"**/build/",
+			"**/cmake-build-*/",
+			"**/coverage/",
+			"**/node_modules/",
+			"**/.idea/",
+		],
+	},
+
+	// Base config for all JS/TS files
+	js.configs.recommended,
+	...tseslint.configs.recommended,
+	eslintConfigPrettier,
+	importX.flatConfigs.recommended,
+	importX.flatConfigs.typescript,
+
+	// Global settings for JS/TS files
+	{
+		languageOptions: {
+			globals: {
+				...globals.node,
+			},
+		},
+		settings: {
+			"import-x/resolver": {
+				typescript: true,
+				node: true,
+			},
+		},
+		rules: {
+			"import-x/no-named-as-default": "off",
+			"import-x/no-named-as-default-member": "off",
+		},
+	},
+
+	// JS/TS specific rules (replaces the *.js, *.ts override)
+	{
+		files: ["**/*.js", "**/*.ts"],
+		plugins: {
+			headers,
+		},
+		rules: {
+			"@typescript-eslint/ban-ts-comment": "off",
+			"@typescript-eslint/no-require-imports": "off",
+			"@typescript-eslint/no-unused-expressions": "off",
+			"@typescript-eslint/no-unused-vars": "off",
+			"headers/header-format": [
+				"error",
+				{
+					source: "string",
+					blockPrefix: "\n",
+					content:
+						'Copyright 2026 Code Intelligence GmbH\n\nLicensed under the Apache License, Version 2.0 (the "License");\nyou may not use this file except in compliance with the License.\nYou may obtain a copy of the License at\n\n     http://www.apache.org/licenses/LICENSE-2.0\n\nUnless required by applicable law or agreed to in writing, software\ndistributed under the License is distributed on an "AS IS" BASIS,\nWITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\nSee the License for the specific language governing permissions and\nlimitations under the License.',
+				},
+			],
+			"import-x/first": "error",
+			"import-x/newline-after-import": "error",
+			"import-x/no-unresolved": "warn",
+			"import-x/order": [
+				"error",
+				{
+					alphabetize: { order: "asc", caseInsensitive: true },
+					"newlines-between": "always",
+					distinctGroup: true,
+					pathGroupsExcludedImportTypes: ["builtin"],
+					pathGroups: [
+						{
+							pattern: "@jazzer.js/**",
+							group: "external",
+							position: "after",
+						},
+					],
+				},
+			],
+			"sort-imports": [
+				"error",
+				{
+					ignoreCase: true,
+					ignoreDeclarationSort: true,
+				},
+			],
+		},
+	},
+
+	// Exclude header check from the header template file itself
+	{
+		files: [".header.js"],
+		rules: {
+			"headers/header-format": "off",
+		},
+	},
+
+	// Disable unresolved import warnings for examples/tests with their own deps
+	{
+		files: ["examples/**", "tests/**"],
+		rules: {
+			"import-x/no-unresolved": "off",
+		},
+	},
+
+	// Jest globals for test and fuzz files
+	{
+		files: ["**/*.test.ts", "**/*.test.js", "**/*.fuzz.ts", "**/*.fuzz.js"],
+		plugins: {
+			jest,
+		},
+		languageOptions: {
+			globals: {
+				...globals.jest,
+			},
+		},
+	},
+
+	// Markdown files
+	{
+		files: ["**/*.md"],
+		plugins: {
+			markdownlint,
+		},
+		languageOptions: {
+			parser: markdownlintParser,
+		},
+		rules: {
+			...markdownlint.configs.recommended.rules,
+			"markdownlint/md010": "off",
+			"markdownlint/md013": "off",
+			"markdownlint/md033": "off",
+			"markdownlint/md041": "off",
+		},
+	},
+);

.eslintrc.json

@@ -16,7 +16,6 @@
 
 const {
 	getBugDetectorConfiguration,
-	// eslint-disable-next-line @typescript-eslint/no-var-requires
 } = require("../../../packages/bug-detectors");
 
 getBugDetectorConfiguration("prototype-pollution")

eslint.config.mjs

@@ -99,7 +99,6 @@ interface PrototypePollution {
 }
 
 declare global {
-	// eslint-disable-next-line no-var
 	var PrototypePollution: PrototypePollution;
 }
 

examples/bug-detectors/prototype-pollution/config.js

@@ -15,7 +15,6 @@
  */
 
 declare global {
-	// eslint-disable-next-line no-var
 	var JazzerJS: Map<string, unknown> | undefined;
 }
 

packages/bug-detectors/internal/prototype-pollution.ts

@@ -28,7 +28,7 @@ export type ReplaceHookFn = (
 	thisPtr: any,
 	params: any[],
 	hookId: number,
-	// eslint-disable-next-line @typescript-eslint/ban-types
+	// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
 	origFn: Function,
 ) => any;
 

packages/core/globals.ts

@@ -226,7 +226,7 @@ export class HookManager {
 					thisPtr,
 					params,
 					callSiteId(),
-					// eslint-disable-next-line @typescript-eslint/ban-types
+					// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
 					resultOrOriginalFunction as Function,
 				);
 			case HookType.After:

packages/hooking/hook.ts

@@ -59,7 +59,6 @@ export function codeCoverage(idStrategy: EdgeIdStrategy): () => PluginTarget {
 	return () => {
 		return {
 			visitor: {
-				// eslint-disable-next-line @typescript-eslint/ban-types
 				Function(path: NodePath<Function>) {
 					if (isBlockStatement(path.node.body)) {
 						const bodyStmt = path.node.body as BlockStatement;

packages/hooking/manager.ts

@@ -946,12 +946,12 @@ function registerHook(
 			target,
 			"pkg",
 			isAsync,
-			// eslint-disable-next-line @typescript-eslint/ban-types
+
 			(
 				thisPtr: unknown,
 				params: number[],
 				_hookId: number,
-				// eslint-disable-next-line @typescript-eslint/ban-types
+				// eslint-disable-next-line @typescript-eslint/no-unsafe-function-type
 				originalFunction: Function,
 			) => {
 				const [calls, hook] = hookCallMap.get(i) as [number, Hook];