diff --git a/src/index.ts b/src/index.ts
index 0a7b80b..9631933 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -234,7 +234,11 @@ export async function create({
   skipFiles?: string[];
   templates: string[];
   getTemplateName: (argv: Argv) => Promise<string>;
-  mapESLintTemplate: (
+  /**
+   * Map the template name to the ESLint template name.
+   * If not provided, defaults to 'vanilla-ts' for all templates.
+   */
+  mapESLintTemplate?: (
     templateName: string,
     context: { distFolder: string },
   ) => ESLintTemplateName | null;
@@ -351,9 +355,11 @@ export async function create({
     const toolFolder = path.join(packageRoot, `template-${tool}`);
 
     if (tool === 'eslint') {
-      const eslintTemplateName = mapESLintTemplate(templateName, {
-        distFolder,
-      });
+      const eslintTemplateName = mapESLintTemplate
+        ? mapESLintTemplate(templateName, {
+            distFolder,
+          })
+        : 'vanilla-ts';
 
       if (!eslintTemplateName) {
         continue;
diff --git a/test/agents.test.ts b/test/agents.test.ts
index b1c0b04..745305a 100644
--- a/test/agents.test.ts
+++ b/test/agents.test.ts
@@ -37,7 +37,6 @@ test('should generate AGENTS.md with no tools selected', async () => {
     root: fixturesDir,
     templates: ['vanilla'],
     getTemplateName: async () => 'vanilla',
-    mapESLintTemplate: () => null,
   });
 
   const agentsPath = path.join(projectDir, 'AGENTS.md');
@@ -92,7 +91,6 @@ test('should generate AGENTS.md with single tool selected', async () => {
     root: fixturesDir,
     templates: ['vanilla'],
     getTemplateName: async () => 'vanilla',
-    mapESLintTemplate: () => null,
   });
 
   const agentsPath = path.join(projectDir, 'AGENTS.md');
@@ -205,7 +203,6 @@ test('should merge top-level sections from AGENTS.md files', async () => {
     root: fixturesDir,
     templates: ['vanilla'],
     getTemplateName: async () => 'vanilla',
-    mapESLintTemplate: () => null,
   });
 
   const agentsPath = path.join(projectDir, 'AGENTS.md');
diff --git a/test/custom-tools.test.ts b/test/custom-tools.test.ts
index d57178f..6f2376c 100644
--- a/test/custom-tools.test.ts
+++ b/test/custom-tools.test.ts
@@ -1,7 +1,7 @@
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
-import { assert, beforeEach, test } from '@rstest/core';
+import { beforeEach, expect, test } from '@rstest/core';
 import fse from 'fs-extra';
 import { create } from '../dist/index.js';
 
@@ -45,7 +45,6 @@ test('should run extra tool action', async () => {
     root: fixturesDir,
     templates: ['vanilla'],
     getTemplateName: async () => 'vanilla',
-    mapESLintTemplate: () => null,
     extraTools: [
       {
         value: 'custom-action',
@@ -57,7 +56,7 @@ test('should run extra tool action', async () => {
     ],
   });
 
-  assert.strictEqual(actionCalled, true);
+  expect(actionCalled).toBe(true);
 });
 
 test('should run extra tool command', async () => {
@@ -82,7 +81,6 @@ test('should run extra tool command', async () => {
     root: fixturesDir,
     templates: ['vanilla'],
     getTemplateName: async () => 'vanilla',
-    mapESLintTemplate: () => null,
     extraTools: [
       {
         value: 'custom-command',
@@ -92,5 +90,5 @@ test('should run extra tool command', async () => {
     ],
   });
 
-  assert.strictEqual(fs.existsSync(touchedFile), true);
+  expect(fs.existsSync(touchedFile)).toBe(true);
 });