diff --git a/CHANGELOG.md b/CHANGELOG.md
index 194c29b..040ebe2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,9 @@ All notable changes to `doc` are documented here.
 
 ### Fixed
 
+- Add an in-app back button to the TopBar that appears only after the first in-app navigation,
+  and scope the entry-document flag to `sessionStorage` so it survives SPA navigation but resets
+  on full page reload (#66).
 - Replace hardcoded `timeAgo` strings with `next-intl` translation keys and return ISO-8601
   `createdAt` from the version API so clients can format timestamps with `Intl.DateTimeFormat`.
   Remove unused `useTimeAgo` hook export and use real `messages/zh-cn.json` in `dt.test.ts`
diff --git a/messages/en.json b/messages/en.json
index 4f59012..e2d3f04 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -9,7 +9,8 @@
     "documentActions": "Document actions",
     "moreDocumentActions": "More document actions",
     "changeLanguage": "Change language, current {locale}",
-    "closeDialog": "Close dialog"
+    "closeDialog": "Close dialog",
+    "goBack": "Go back"
   },
   "metadata": {
     "title": "doc — self-hosted collaborative document infrastructure",
diff --git a/messages/zh-cn.json b/messages/zh-cn.json
index ea6bf72..c3f632e 100644
--- a/messages/zh-cn.json
+++ b/messages/zh-cn.json
@@ -9,7 +9,8 @@
     "documentActions": "文档操作",
     "moreDocumentActions": "更多文档操作",
     "changeLanguage": "切换语言，当前为 {locale}",
-    "closeDialog": "关闭对话框"
+    "closeDialog": "关闭对话框",
+    "goBack": "返回上一页"
   },
   "metadata": {
     "title": "doc — 自托管协作文档基础设施",
diff --git a/src/app/[locale]/work/[id]/(content)/content-for-my-doc.tsx b/src/app/[locale]/work/[id]/(content)/content-for-my-doc.tsx
index cccfc08..7551aaa 100644
--- a/src/app/[locale]/work/[id]/(content)/content-for-my-doc.tsx
+++ b/src/app/[locale]/work/[id]/(content)/content-for-my-doc.tsx
@@ -27,9 +27,13 @@ export default function ContentForMyDoc() {
   const updateDocTitle = useDocsStore((s) => s.updateDocTitle)
   const updateDocIcon = useDocsStore((s) => s.updateDocIcon)
 
-  // record last doc id
+  // Record entry doc id only once per page session.
+  // Uses sessionStorage to survive SPA navigation but reset on full page reload.
   useEffect(() => {
-    localStorage.setItem(LAST_DOC_ID_KEY, id) // 保存最后一次打开的文档 id
+    if (!sessionStorage.getItem('hasRecordedEntryDoc')) {
+      localStorage.setItem(LAST_DOC_ID_KEY, id)
+      sessionStorage.setItem('hasRecordedEntryDoc', 'true')
+    }
   }, [id])
 
   useEffect(() => {
diff --git a/src/app/[locale]/work/[id]/top-bar.tsx b/src/app/[locale]/work/[id]/top-bar.tsx
index 61aa73c..c35c18e 100644
--- a/src/app/[locale]/work/[id]/top-bar.tsx
+++ b/src/app/[locale]/work/[id]/top-bar.tsx
@@ -1,7 +1,7 @@
 'use client'
 
-import { useMemo, useState } from 'react'
-import { Ellipsis } from 'lucide-react'
+import { useMemo, useState, useEffect } from 'react'
+import { ArrowLeft, Ellipsis } from 'lucide-react'
 import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover'
 import { Button } from '@/components/ui/button'
 import Logo from '@/components/logo-component'
@@ -24,6 +24,8 @@ import { useUserStore } from '@/stores/user-store'
 import { Topbar } from '@fullstack-ai-infra/ui'
 import { useTranslations } from 'next-intl'
 import { useCompactWorkspace } from '@/hooks/use-compact-workspace'
+import emitter from '@/lib/emitter'
+import { EVENT_KEY_NAV_DOC } from '@/constants'
 
 export default function TopBar() {
   const t = useTranslations('common')
@@ -33,12 +35,33 @@ export default function TopBar() {
   const doc = useMemo(() => docs.find((d) => d.id === id), [docs, id])
   const userInfo = useUserStore((s) => s.userInfo)
 
+  // Track whether there's in-app navigation history for the back button.
+  const [hasHistory, setHasHistory] = useState(false)
+  useEffect(() => {
+    const onNav = () => setHasHistory(true)
+    emitter.on(EVENT_KEY_NAV_DOC, onNav)
+    return () => {
+      emitter.off(EVENT_KEY_NAV_DOC, onNav)
+    }
+  }, [])
+
   return (
     <Topbar
       aria-label={t('documentToolbar')}
       className="max-[1023px]:pl-14 max-[480px]:pr-2"
       breadcrumbs={
         <div className="inline-flex items-center gap-3">
+          {hasHistory && (
+            <Button
+              type="button"
+              variant="ghost"
+              size="icon"
+              aria-label={t('goBack')}
+              onClick={() => window.history.back()}
+            >
+              <ArrowLeft aria-hidden="true" className="h-4 w-4" />
+            </Button>
+          )}
           <Logo />
           <div className="max-[479px]:hidden">
             <DocUpdateStatus id={id} />