fix: parse Day.js input with the picker locale

src/generate/dayjs.ts

@@ -165,7 +165,8 @@ const generateConfig: GenerateConfig<Dayjs> = {
     getShortMonths: (locale) => dayjs().locale(parseLocale(locale)).localeData().monthsShort(),
     format: (locale, date, format) => getUDayjs(date).locale(parseLocale(locale)).format(format),
     parse: (locale, text, formats) => {
-      const localeStr = parseLocale(locale);
+      // Preserve Day.js fallback when the requested locale data is not registered.
+      const localeStr = dayjs().locale(parseLocale(locale)).locale();
       for (let i = 0; i < formats.length; i += 1) {
         const format = formats[i];
         const formatText = text;
@@ -183,7 +184,7 @@ const generateConfig: GenerateConfig<Dayjs> = {
           parseNoMatchNotice();
           return null;
         }
-        const date = dayjs(formatText, format, true).locale(localeStr);
+        const date = dayjs(formatText, format, localeStr, true);
         if (date.isValid()) {
           return date;
         }

tests/generate.spec.tsx

@@ -1,4 +1,5 @@
 import MockDate from 'mockdate';
+import dayjs from 'dayjs';
 import dateFnsGenerateConfig from '../src/generate/dateFns';
 import dayjsGenerateConfig from '../src/generate/dayjs';
 import luxonGenerateConfig from '../src/generate/luxon';
@@ -7,6 +8,7 @@ import { getMoment } from './util/commonUtil';
 
 import 'dayjs/locale/zh-cn';
 import 'dayjs/locale/ko';
+import 'dayjs/locale/fr';
 import type { GenerateConfig } from '../src/generate';
 
 describe('Picker.Generate', () => {
@@ -289,6 +291,68 @@ describe('Generate:moment', () => {
 });
 
 describe('Generate:dayjs', () => {
+  describe('locale-aware parsing', () => {
+    let originalLocale: string;
+
+    beforeEach(() => {
+      originalLocale = dayjs.locale();
+      dayjs.locale('en');
+    });
+
+    afterEach(() => {
+      dayjs.locale(originalLocale);
+    });
+
+    it.each([
+      ['fr_FR', '25 août 2026', 'D MMM YYYY', '2026-08-25'],
+      ['fr_FR', '25 septembre 2026', 'D MMMM YYYY', '2026-09-25'],
+      ['fr_BE', '25 août 2026', 'D MMM YYYY', '2026-08-25'],
+    ])('parses %s text %s without changing the global locale', (locale, text, format, expected) => {
+      const date = dayjsGenerateConfig.locale.parse(locale, text, [format]);
+
+      expect(date?.format('YYYY-MM-DD')).toBe(expected);
+      expect(date?.locale()).toBe('fr');
+      expect(dayjs.locale()).toBe('en');
+    });
+
+    it('tries alternate formats with the requested locale', () => {
+      const date = dayjsGenerateConfig.locale.parse('fr_FR', '25 août 2026', [
+        'YYYY-MM-DD',
+        'D MMM YYYY',
+      ]);
+
+      expect(date?.format('YYYY-MM-DD')).toBe('2026-08-25');
+      expect(dayjs.locale()).toBe('en');
+    });
+
+    it('parses English text when the global locale is French', () => {
+      dayjs.locale('fr');
+      const date = dayjsGenerateConfig.locale.parse('en_US', '25 Aug 2026', ['D MMM YYYY']);
+
+      expect(date?.format('YYYY-MM-DD')).toBe('2026-08-25');
+      expect(date?.locale()).toBe('en');
+      expect(dayjs.locale()).toBe('fr');
+    });
+
+    it('keeps the global-locale fallback when locale data is not registered', () => {
+      const date = dayjsGenerateConfig.locale.parse('unregistered_LOCALE', '25 Aug 2026', [
+        'D MMM YYYY',
+      ]);
+
+      expect(date?.format('YYYY-MM-DD')).toBe('2026-08-25');
+      expect(date?.locale()).toBe('en');
+      expect(dayjs.locale()).toBe('en');
+    });
+
+    it.each(['31 février 2026', '25 août 2026 extra'])(
+      'keeps strict validation for localized input %s',
+      (text) => {
+        expect(dayjsGenerateConfig.locale.parse('fr_FR', text, ['D MMMM YYYY'])).toBeNull();
+        expect(dayjs.locale()).toBe('en');
+      },
+    );
+  });
+
   it('getFixedDate', () => {
     const timea = dayjsGenerateConfig.getFixedDate('2019-2-08');
     const timeb = dayjsGenerateConfig.getFixedDate('2019-02-08');

tests/picker.spec.tsx

@@ -2,6 +2,7 @@
 import { act, createEvent, fireEvent, render } from '@testing-library/react';
 import type { Dayjs } from 'dayjs';
 import dayjs from 'dayjs';
+import 'dayjs/locale/fr';
 import moment from 'moment';
 import 'moment/locale/zh-cn';
 import { KeyCode, resetWarned, spyElementPrototypes } from '@rc-component/util';
@@ -10,6 +11,7 @@ import Picker, { PickerPanel, type PickerRef } from '../src';
 import type { PanelMode, PickerMode } from '../src/interface';
 import momentGenerateConfig from '../src/generate/moment';
 import enUS from '../src/locale/en_US';
+import frFR from '../src/locale/fr_FR';
 import zhCN from '../src/locale/zh_CN';
 import {
   // MomentPicker,
@@ -66,6 +68,36 @@ describe('Picker.Basic', () => {
     fireEvent.click(document.querySelectorAll('ul')[colIndex].querySelectorAll('li')[rowIndex]);
   }
 
+  it('commits edited localized month text while the global locale stays English', () => {
+    const originalLocale = dayjs.locale();
+    dayjs.locale('en');
+
+    try {
+      const onChange = jest.fn();
+      const { container } = render(
+        <DayPicker
+          locale={frFR}
+          format="D MMM YYYY"
+          defaultValue={getDay('2026-08-24')}
+          onChange={onChange}
+        />,
+      );
+      const input = container.querySelector('input');
+      expect(input.value).toBe('24 août 2026');
+
+      fireEvent.change(input, { target: { value: '25 août 2026' } });
+      keyDown(KeyCode.ENTER);
+
+      expect(onChange).toHaveBeenCalledTimes(1);
+      expect(onChange.mock.calls[0][0].format('YYYY-MM-DD')).toBe('2026-08-25');
+      expect(onChange.mock.calls[0][1]).toBe('25 août 2026');
+      expect(input).not.toHaveAttribute('aria-invalid', 'true');
+      expect(dayjs.locale()).toBe('en');
+    } finally {
+      dayjs.locale(originalLocale);
+    }
+  });
+
   describe('mode', () => {
     const modeList: { mode: PanelMode; className: string }[] = [
       {