fix: stop the template picker from raising a React key error in development

components/templates/__tests__/template-picker-manage.test.tsx

@@ -1,5 +1,7 @@
 import { fireEvent, render, screen } from '@testing-library/react';
 import { describe, expect, it, vi } from 'vitest';
+import { useTemplateStore } from '@/stores/template-store';
+import type { EmailTemplate } from '@/lib/template-types';
 
 // The template picker offers "Manage templates", so making or fixing a
 // template doesn't need a trip to Settings in the middle of a message.
@@ -19,4 +21,19 @@ describe('TemplatePicker', () => {
     fireEvent.click(screen.getByText('done'));
     expect(screen.getByRole('dialog', { name: 'picker_title' })).toBeTruthy();
   });
+
+  // The sections (favorites, recent, each category) are a list: without
+  // keys React warned, which the dev build shows as an error overlay.
+  it('renders its sections without a React key warning', () => {
+    const template = (id: string, category: string, isFavorite = false): EmailTemplate => ({
+      id, name: `T ${id}`, subject: '', body: '', category, isFavorite,
+      createdAt: '2026-10-01T00:00:00Z', updatedAt: '2026-10-01T00:00:00Z', usageCount: 0,
+    } as EmailTemplate);
+    useTemplateStore.setState({ templates: [template('a', 'Work', true), template('b', 'Work'), template('c', 'Home'), template('d', '')] });
+    const error = vi.spyOn(console, 'error').mockImplementation(() => {});
+    render(<TemplatePicker isOpen onClose={vi.fn()} onSelect={vi.fn()} />);
+    expect(screen.getByText('T c')).toBeTruthy();
+    expect(error.mock.calls.some((call) => String(call[0]).includes('unique "key"'))).toBe(false);
+    error.mockRestore();
+  });
 });

components/templates/template-picker.tsx

@@ -97,10 +97,10 @@ export function TemplatePicker({ isOpen, onClose, onSelect }: TemplatePickerProp
     </button>
   );
 
-  const renderSection = (title: string, items: EmailTemplate[]) => {
+  const renderSection = (key: string, title: string, items: EmailTemplate[]) => {
     if (items.length === 0) return null;
     return (
-      <div className="mb-4">
+      <div key={key} className="mb-4">
         <h3 className="text-xs font-semibold text-muted-foreground uppercase tracking-wider mb-1 px-3">
           {title}
         </h3>
@@ -171,15 +171,16 @@ export function TemplatePicker({ isOpen, onClose, onSelect }: TemplatePickerProp
               )
             ) : (
               <>
-                {renderSection(t('section_favorites'), favorites)}
-                {renderSection(t('section_recent'), recentFiltered)}
+                {renderSection('favorites', t('section_favorites'), favorites)}
+                {renderSection('recent', t('section_recent'), recentFiltered)}
                 {categorizedEntries.map(([cat, items]) =>
                   renderSection(
+                    `category:${cat}`,
                     cat,
                     items.filter((i) => !shownIds.has(i.id))
                   )
                 )}
-                {renderSection(t('section_uncategorized'), uncategorizedFiltered)}
+                {renderSection('uncategorized', t('section_uncategorized'), uncategorizedFiltered)}
               </>
             )}
           </div>