fix: eslint auto import type declaration

packages/wxt/e2e/tests/__snapshots__/auto-imports.test.ts.snap

@@ -119,6 +119,15 @@ export default {
 "
 `;
 
+exports[`Auto Imports > eslint config > "enabled: 9" should output a flat config file compatible with ESLint >=9 2`] = `
+".wxt/eslint-auto-imports.d.mts
+----------------------------------------
+import type { ConfigObject } from "@eslint/core";
+declare const config: ConfigObject;
+export default config;
+"
+`;
+
 exports[`Auto Imports > eslint config > "enabled: auto" should output a JSON config file compatible with ESLint of package.json 1`] = `
 ".wxt/eslint-auto-imports.mjs
 ----------------------------------------
@@ -182,6 +191,15 @@ export default {
 "
 `;
 
+exports[`Auto Imports > eslint config > "enabled: auto" should output a JSON config file compatible with ESLint of package.json 2`] = `
+".wxt/eslint-auto-imports.d.mts
+----------------------------------------
+import type { ConfigObject } from "@eslint/core";
+declare const config: ConfigObject;
+export default config;
+"
+`;
+
 exports[`Auto Imports > eslint config > "enabled: true" should output a JSON config file compatible with ESLint of package.json 1`] = `
 ".wxt/eslint-auto-imports.mjs
 ----------------------------------------
@@ -245,6 +263,15 @@ export default {
 "
 `;
 
+exports[`Auto Imports > eslint config > "enabled: true" should output a JSON config file compatible with ESLint of package.json 2`] = `
+".wxt/eslint-auto-imports.d.mts
+----------------------------------------
+import type { ConfigObject } from "@eslint/core";
+declare const config: ConfigObject;
+export default config;
+"
+`;
+
 exports[`Auto Imports > eslint config > should allow customizing the output 1`] = `
 "example.json
 ----------------------------------------
@@ -307,3 +334,12 @@ export default {
 };
 "
 `;
+
+exports[`Auto Imports > eslint config > should allow customizing the output 2`] = `
+"example.d.ts
+----------------------------------------
+import type { ConfigObject } from "@eslint/core";
+declare const config: ConfigObject;
+export default config;
+"
+`;

packages/wxt/e2e/tests/auto-imports.test.ts

@@ -235,6 +235,9 @@ describe('Auto Imports', () => {
         expect(
           await project.serializeFile('.wxt/eslint-auto-imports.mjs'),
         ).toMatchSnapshot();
+        expect(
+          await project.serializeFile('.wxt/eslint-auto-imports.d.mts'),
+        ).toMatchSnapshot();
       },
     );
 
@@ -270,6 +273,9 @@ describe('Auto Imports', () => {
       expect(
         await project.serializeFile('.wxt/eslint-auto-imports.mjs'),
       ).toMatchSnapshot();
+      expect(
+        await project.serializeFile('.wxt/eslint-auto-imports.d.mts'),
+      ).toMatchSnapshot();
     });
 
     it('"enabled: false" should NOT output an ESLint config file', async () => {
@@ -307,6 +313,7 @@ describe('Auto Imports', () => {
       });
 
       expect(await project.serializeFile('example.json')).toMatchSnapshot();
+      expect(await project.serializeFile('example.d.ts')).toMatchSnapshot();
     });
 
     describe('Actual linting results', () => {

packages/wxt/src/builtin-modules/unimport.ts

@@ -7,8 +7,9 @@ import type {
   WxtResolvedUnimportOptions,
   EslintConfigVersion,
 } from '../types';
-import { type Unimport, createUnimport, toExports } from 'unimport';
+import { createUnimport, toExports, type Unimport } from 'unimport';
 import UnimportPlugin from 'unimport/unplugin';
+import { extname } from 'node:path';
 
 export default defineWxtModule({
   name: 'wxt:built-in:unimport',
@@ -52,14 +53,13 @@ export default defineWxtModule({
 
       if (!wxt.config.imports.eslintrc.enabled) return;
 
-      // Only generate ESLint config if that feature is enabled
-      entries.push(
-        await getEslintConfigEntry(
-          unimport,
-          wxt.config.imports.eslintrc.enabled,
-          wxt.config.imports,
-        ),
+      const eslintConfigEntries = await getEslintConfigEntry(
+        unimport,
+        wxt.config.imports.eslintrc.enabled,
+        wxt.config.imports,
       );
+
+      entries.push(...eslintConfigEntries);
     });
 
     // Add vite plugin
@@ -106,7 +106,7 @@ async function getEslintConfigEntry(
   unimport: Unimport,
   configVersion: EslintConfigVersion,
   options: WxtResolvedUnimportOptions,
-): Promise<WxtDirFileEntry> {
+): Promise<WxtDirFileEntry[]> {
   const globals = (await unimport.getImports())
     .map((i) => i.as ?? i.name)
     .filter(Boolean)
@@ -123,18 +123,20 @@ async function getEslintConfigEntry(
 export function getEslint8ConfigEntry(
   options: WxtResolvedUnimportOptions,
   globals: Record<string, EslintGlobalsPropValue>,
-): WxtDirFileEntry {
-  return {
-    path: options.eslintrc.filePath,
-    text: JSON.stringify({ globals }, null, 2) + '\n',
-  };
+): WxtDirFileEntry[] {
+  return [
+    {
+      path: options.eslintrc.filePath,
+      text: JSON.stringify({ globals }, null, 2) + '\n',
+    },
+  ];
 }
 
 export function getEslint9ConfigEntry(
   options: WxtResolvedUnimportOptions,
   globals: Record<string, EslintGlobalsPropValue>,
-): WxtDirFileEntry {
-  return {
+): WxtDirFileEntry[] {
+  const javaScriptFileEntry: WxtDirFileEntry = {
     path: options.eslintrc.filePath,
     text: `const globals = ${JSON.stringify(globals, null, 2)}
 
@@ -148,4 +150,20 @@ export default {
 };
 `,
   };
+
+  const ext = extname(options.eslintrc.filePath);
+  const declarationExt =
+    ext === '.mjs' ? '.d.mts' : ext === '.cjs' ? '.d.cts' : '.d.ts';
+  const typeScriptFilePath =
+    options.eslintrc.filePath.slice(0, -ext.length) + declarationExt;
+
+  const typeScriptFileEntry: WxtDirFileEntry = {
+    path: typeScriptFilePath,
+    text: `import type { ConfigObject } from "@eslint/core";
+declare const config: ConfigObject;
+export default config;
+`,
+  };
+
+  return [javaScriptFileEntry, typeScriptFileEntry];
 }