fix(runtime): replace history on no_prefix locale switch

router.push duplicated identical history entries under
no_prefix (#238). Use replace; keep push for prefixes.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: s00d

docs/news/index.md

@@ -6,6 +6,14 @@ outline: 'deep'
 
 # News
 
+## Unreleased — no_prefix locale switch history (#238)
+
+**Date**: 2026-07-31
+
+Switching locale under `strategy: 'no_prefix'` no longer pushes a duplicate identical history entry. `switchLocalePath` / locale switch now uses `router.replace` when the URL path is unchanged; prefix strategies still use `router.push`.
+
+---
+
 ## Nuxt I18n Micro v3.24.0 — Node SSR from `public/`, no Rollup `raw:`
 
 **Date**: 2026-07-30

package.json

@@ -1,6 +1,6 @@
 {
   "name": "nuxt-i18n-micro",
-  "version": "3.24.1",
+  "version": "3.24.2",
   "description": "Nuxt I18n Micro is a lightweight, high-performance internationalization module for Nuxt, designed to handle multi-language support with minimal overhead, fast build times, and efficient runtime performance.",
   "keywords": [
     "i18n",

src/runtime/utils/nuxt-i18n.ts

@@ -433,7 +433,9 @@ export function createNuxtI18nPluginApi(deps: NuxtI18nPluginApiDeps) {
     }
 
     if (isNoPrefix) {
+      // URL stays the same under no_prefix — push would append a duplicate history entry (#238).
       ;(switchedRoute as RouteLocationRaw & { force?: boolean }).force = true
+      return router.replace(switchedRoute as RouteLocationRaw)
     }
 
     return router.push(switchedRoute as RouteLocationRaw)

test/switch-locale-no-prefix-history.test.ts

@@ -0,0 +1,92 @@
+import type { PathStrategy } from '@i18n-micro/path-strategy'
+import type { ModuleOptionsExtend } from '@i18n-micro/types'
+import { describe, expect, it, vi } from 'vitest'
+import type { Router } from 'vue-router'
+import { createNuxtI18nPluginApi, NuxtI18n, NuxtTranslationLoader } from '../src/runtime/utils/nuxt-i18n'
+
+/**
+ * Issue #238: under `no_prefix` the URL does not change on locale switch, so
+ * `router.push` appends a duplicate history entry. Switching must `replace`.
+ */
+function makeApi(strategy: ModuleOptionsExtend['strategy']) {
+  const push = vi.fn<(to?: unknown) => Promise<undefined>>(async () => undefined)
+  const replace = vi.fn<(to?: unknown) => Promise<undefined>>(async () => undefined)
+  const currentRoute = {
+    path: '/',
+    fullPath: '/',
+    name: 'index',
+    params: {},
+    query: {},
+    hash: '',
+    matched: [],
+    meta: {},
+    redirectedFrom: undefined,
+  }
+
+  const router = {
+    push,
+    replace,
+    currentRoute: { value: currentRoute },
+    resolve: (to: unknown) => (typeof to === 'object' && to !== null ? { ...currentRoute, ...to } : currentRoute),
+  } as unknown as Router
+
+  const i18n = new NuxtI18n({ missingWarn: false })
+  const loader = new NuxtTranslationLoader({
+    i18n,
+    loadOptions: { apiBaseUrl: '_locales', baseURL: '/' },
+  })
+  vi.spyOn(loader, 'switchContext').mockResolvedValue(undefined)
+
+  const i18nStrategy = {
+    switchLocaleRoute: () => ({ path: '/', name: 'index', force: undefined }),
+    formatPathForResolve: (path: string) => path,
+  } as unknown as PathStrategy
+
+  const { provide } = createNuxtI18nPluginApi({
+    i18n,
+    loader,
+    i18nStrategy,
+    i18nConfig: {
+      strategy,
+      defaultLocale: 'en',
+      locales: [
+        { code: 'en', iso: 'en' },
+        { code: 'es', iso: 'es' },
+      ],
+    } as ModuleOptionsExtend,
+    router,
+    getCurrentLocale: () => 'en',
+    getEffectiveLocale: () => 'en',
+    getPluginRouteName: () => 'index',
+    getRouteName: () => 'index',
+    i18nRouteParams: { value: {} },
+    setLocale: vi.fn(),
+    isValidLocale: () => true,
+    navigateTo: vi.fn(),
+    setMissingHandler: vi.fn(),
+  })
+
+  return { provide, push, replace }
+}
+
+describe('switchLocale history (#238)', () => {
+  it('uses router.replace under no_prefix so history.length does not grow', async () => {
+    const { provide, push, replace } = makeApi('no_prefix')
+
+    await provide.switchLocale('es')
+
+    expect(replace).toHaveBeenCalledTimes(1)
+    expect(push).not.toHaveBeenCalled()
+    const arg = replace.mock.calls[0]?.[0] as { force?: boolean; path?: string } | undefined
+    expect(arg).toEqual(expect.objectContaining({ force: true, path: '/' }))
+  })
+
+  it('keeps router.push for prefixed strategies', async () => {
+    const { provide, push, replace } = makeApi('prefix')
+
+    await provide.switchLocale('es')
+
+    expect(push).toHaveBeenCalledTimes(1)
+    expect(replace).not.toHaveBeenCalled()
+  })
+})