diff --git a/openspec/changes/add-namespace-invite-links/specs/namespace-invitations/spec.md b/openspec/changes/add-namespace-invite-links/specs/namespace-invitations/spec.md
index f1f2769c..9f7277f5 100644
--- a/openspec/changes/add-namespace-invite-links/specs/namespace-invitations/spec.md
+++ b/openspec/changes/add-namespace-invite-links/specs/namespace-invitations/spec.md
@@ -85,7 +85,7 @@ Token 原始随机字节不得少于 32 字节，并采用 Base64URL 编码；
 
 前端 SHALL 完成链接分享、登录回跳和邀请状态闭环。
 
-空间卡片提供单击创建并复制邀请的入口，有仍可兑换的旧链接时先确认替换；成员管理页也提供生成、替换确认、复制失败后的手动复制以及单独作废；接收页提供加载、确认、已加入和失效状态。成功、已加入或终态失效时清除 sessionStorage 中的 Token；已加入预览一旦成功即清除 Token，随后进入空间时替换浏览器历史中的邀请页。网络错误保留 Token 以重试。生成公开链接必须复用现有公开基地址解析方式，清理 fragment 时保留当前 path 和 query。中文、英文和俄文文案均覆盖。
+空间卡片提供单击创建并复制邀请的入口，有仍可兑换的旧链接时先确认替换；成员管理页也提供生成、替换确认、复制失败后的手动复制以及单独作废；接收页提供加载、确认、已加入和失效状态。成功、已加入或终态失效时清除 sessionStorage 中的 Token；已加入预览一旦成功即清除 Token 并自动使用 replace 导航进入空间，避免重复导航。加载状态使用可访问的 status 提示，终态失效使用 alert 提示。网络错误保留 Token 以重试。生成公开链接必须复用现有公开基地址解析方式，清理 fragment 时保留当前 path 和 query。中文、英文和俄文文案均覆盖。
 
 #### Scenario: 剪贴板写入失败
 - **WHEN** 创建成功但浏览器拒绝写剪贴板
diff --git a/web/src/pages/join.test.tsx b/web/src/pages/join.test.tsx
new file mode 100644
index 00000000..c2452441
--- /dev/null
+++ b/web/src/pages/join.test.tsx
@@ -0,0 +1,84 @@
+/** @vitest-environment jsdom */
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import { cleanup, render, screen, waitFor } from '@testing-library/react'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const mocks = vi.hoisted(() => ({
+  navigate: vi.fn(),
+  preview: vi.fn(),
+  accept: vi.fn(),
+}))
+
+vi.mock('@tanstack/react-router', () => ({ useNavigate: () => mocks.navigate }))
+vi.mock('react-i18next', () => ({ useTranslation: () => ({ t: (key: string) => key }) }))
+vi.mock('@/api/client', () => ({
+  namespaceApi: { previewInvitation: mocks.preview, acceptInvitation: mocks.accept },
+}))
+vi.mock('@/features/auth/use-auth', () => ({
+  useAuth: () => ({ user: { userId: 'guest', displayName: 'Guest' } }),
+}))
+vi.mock('@/shared/lib/api-error', () => ({
+  ApiError: class ApiError extends Error {
+    constructor(message: string, public status: number) { super(message) }
+  },
+}))
+
+import { ApiError } from '@/shared/lib/api-error'
+import { JoinPage } from './join'
+
+const token = 'A'.repeat(43)
+
+function renderJoin() {
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } })
+  return { client, ...render(<QueryClientProvider client={client}><JoinPage /></QueryClientProvider>) }
+}
+
+describe('JoinPage', () => {
+  beforeEach(() => {
+    window.sessionStorage.clear()
+    window.history.replaceState(null, '', '/')
+    mocks.navigate.mockReset()
+    mocks.preview.mockReset()
+    mocks.accept.mockReset()
+  })
+
+  afterEach(cleanup)
+
+  it('clears the token and navigates once with replace when preview finds an existing member', async () => {
+    window.history.replaceState(null, '', `/join#${token}`)
+    mocks.preview.mockResolvedValue({
+      namespaceSlug: 'team', namespaceDisplayName: 'Team', namespaceAvatarUrl: null,
+      outcome: 'ALREADY_MEMBER', expiresAt: '2026-10-13T00:00:00Z',
+    })
+
+    const view = renderJoin()
+
+    await waitFor(() => expect(mocks.navigate).toHaveBeenCalledWith({
+      to: '/space/$namespace', params: { namespace: 'team' }, replace: true,
+    }))
+    expect(window.sessionStorage.length).toBe(0)
+    expect(window.location.hash).toBe('')
+    view.rerender(<QueryClientProvider client={view.client}><JoinPage /></QueryClientProvider>)
+    expect(mocks.navigate).toHaveBeenCalledTimes(1)
+    expect(screen.queryByRole('button', { name: 'invitation.enter' })).toBeNull()
+  })
+
+  it('announces loading while preview is pending', () => {
+    window.history.replaceState(null, '', `/join#${token}`)
+    mocks.preview.mockImplementation(() => new Promise(() => {}))
+
+    renderJoin()
+
+    expect(screen.getByRole('status').textContent).toBe('invitation.loading')
+  })
+
+  it('announces a terminal invalid link', async () => {
+    window.history.replaceState(null, '', `/join#${token}`)
+    mocks.preview.mockRejectedValue(new ApiError('invalid', 404))
+
+    renderJoin()
+
+    expect((await screen.findByRole('alert')).textContent).toBe('invitation.invalid')
+    expect(window.sessionStorage.length).toBe(0)
+  })
+})
diff --git a/web/src/pages/join.tsx b/web/src/pages/join.tsx
index 74b672b1..60dc8d6a 100644
--- a/web/src/pages/join.tsx
+++ b/web/src/pages/join.tsx
@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react'
+import { useEffect, useRef, useState } from 'react'
 import { useNavigate } from '@tanstack/react-router'
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import { useTranslation } from 'react-i18next'
@@ -14,6 +14,7 @@ export function JoinPage() {
   const navigate = useNavigate()
   const queryClient = useQueryClient()
   const { user } = useAuth()
+  const enteredNamespace = useRef(false)
   const [token] = useState(() => {
     captureInvitationFragment()
     return storedInvitationToken()
@@ -35,14 +36,19 @@ export function JoinPage() {
   const invalid = !token || (preview.error instanceof ApiError && preview.error.status === 404)
     || (accept.error instanceof ApiError && accept.error.status === 404)
   useEffect(() => { if (invalid) clearInvitationToken() }, [invalid])
-  useEffect(() => { if (preview.data?.outcome === 'ALREADY_MEMBER') clearInvitationToken() }, [preview.data?.outcome])
+  useEffect(() => {
+    if (preview.data?.outcome !== 'ALREADY_MEMBER' || enteredNamespace.current) return
+    enteredNamespace.current = true
+    clearInvitationToken()
+    void navigate({ to: '/space/$namespace', params: { namespace: preview.data.namespaceSlug }, replace: true })
+  }, [navigate, preview.data])
 
   return (
     <div className="mx-auto max-w-xl px-4 py-16">
       <Card className="space-y-5 p-8">
         <h1 className="text-2xl font-semibold">{t('invitation.title')}</h1>
-        {invalid ? <p>{t('invitation.invalid')}</p> : null}
-        {!invalid && preview.isPending ? <p>{t('invitation.loading')}</p> : null}
+        {invalid ? <p role="alert">{t('invitation.invalid')}</p> : null}
+        {!invalid && preview.isPending ? <p role="status">{t('invitation.loading')}</p> : null}
         {!invalid && preview.error ? (
           <div className="space-y-3">
             <p role="alert">{t('invitation.networkError')}</p>
@@ -54,10 +60,7 @@ export function JoinPage() {
             <p>{t('invitation.namespace', { name: preview.data.namespaceDisplayName })}</p>
             <p>{t('invitation.account', { name: user?.displayName ?? user?.userId ?? '' })}</p>
             {preview.data.outcome === 'ALREADY_MEMBER' ? (
-              <>
-                <p>{t('invitation.alreadyMember')}</p>
-                <Button onClick={() => { clearInvitationToken(); navigate({ to: '/space/$namespace', params: { namespace: preview.data.namespaceSlug }, replace: true }) }}>{t('invitation.enter')}</Button>
-              </>
+              <p role="status">{t('invitation.alreadyMember')}</p>
             ) : (
               <>
                 <p>{t('invitation.permissions')}</p>