diff --git a/src/store.ts b/src/store.ts
index b3eb32b..3766b70 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -539,9 +539,11 @@ export const store = {
       if (pid !== state.currentProjectId) await store.openProject(pid)
       if (epoch !== identityEpoch) throw new Error('登录状态已变化，请重新选择项目后再试')
       const c = await api.createConversation(pid)
-      if (epoch !== identityEpoch) return
+      if (epoch !== identityEpoch) throw new Error('登录状态已变化，请重新选择项目后再试')
       await store.refreshTasks()
-      if (epoch === identityEpoch) await store.openTask(c.id)
+      if (epoch !== identityEpoch) throw new Error('登录状态已变化，请重新选择项目后再试')
+      await store.openTask(c.id)
+      if (epoch !== identityEpoch) throw new Error('登录状态已变化，请重新选择项目后再试')
     } catch (e) {
       if (epoch === identityEpoch) store.toast(`对话创建失败：${projectActionError(e)}`)
       throw e
@@ -556,8 +558,10 @@ export const store = {
 
   /** 打开任务：跨项目点击时切换项目上下文（工件/上传归属正确）。 */
   async openTask(convId: string) {
+    const epoch = identityEpoch
     const t = state.tasks.find(x => x.id === convId)
     if (t && t.projectId !== state.currentProjectId) await store.openProject(t.projectId)
+    if (epoch !== identityEpoch) return
     await store.openConversation(convId)
   },
 
@@ -1196,7 +1200,7 @@ export const store = {
       if (epoch !== identityEpoch || state.currentProjectId !== pid) return null
       store.toast(`已收到材料：${up.filename}${up.parsed ? ' · 已读取内容' : ''}`)
       await store.refreshArtifacts(pid)
-      return up.artifactId
+      return epoch === identityEpoch && state.currentProjectId === pid ? up.artifactId : null
     } catch (e) {
       if (epoch === identityEpoch && state.currentProjectId === pid) store.toast('材料未能上传，请检查文件后重新选择')
       return null
@@ -1296,12 +1300,18 @@ export const store = {
   },
 
   async tidyCards() {
+    const epoch = identityEpoch
     // U1：不收纳失败语义卡（failed，或旧 done+danger），避免把失败当完成清掉。
     const done = state.cards.filter(c => c.status === 'done' && c.tone !== 'danger')
     for (const c of done) {
-      try { const out = await api.cardDismiss(c.id); store.upsertCard(out.card) } catch { /* 单卡失败不阻断 */ }
+      if (epoch !== identityEpoch) return
+      try {
+        const out = await api.cardDismiss(c.id)
+        if (epoch !== identityEpoch) return
+        store.upsertCard(out.card)
+      } catch { /* 单卡失败不阻断 */ }
     }
-    if (done.length > 0) store.toast(`已收纳 ${done.length} 张完成卡`)
+    if (epoch === identityEpoch && done.length > 0) store.toast(`已收纳 ${done.length} 张完成卡`)
   },
   closeWorkspace() { setUI({ activeWorkspace: null }) },
   /** 铃铛：打开右栏并切到待处理。哪一侧有待办就看哪一侧。 */
diff --git a/test/project-access.test.ts b/test/project-access.test.ts
index 5ff23cc..6266b3e 100644
--- a/test/project-access.test.ts
+++ b/test/project-access.test.ts
@@ -249,17 +249,18 @@ describe('identity-scoped state', () => {
     expect(store.getState().artifacts).toEqual([])
   })
 
-  it.each(['action', 'pin', 'dismiss', 'to-project'] as const)('ignores a late project card %s from the previous account on the same shared project', async operation => {
+  it.each(['action', 'pin', 'dismiss', 'to-project', 'tidy'] as const)('ignores a late project card %s from the previous account on the same shared project', async operation => {
     projects = [ready]
     await store.refreshProjects()
     const old = deferred<Response>()
     const previous = route
     route = (path, init) => path.startsWith('/api/cards/') ? old.promise : previous(path, init)
     const card: ActivityCard = { id: 'alice-card', projectId: 'host-1', kind: 'progress', status: 'active', title: 'Alice private work', createdAt: '', updatedAt: '' }
+    if (operation === 'tidy') store.upsertCard({ ...card, status: 'done' })
     const pending = operation === 'action' ? store.cardAction(card, 'finish')
       : operation === 'pin' ? store.cardPin(card, true)
       : operation === 'dismiss' ? store.cardDismiss(card)
-      : store.cardToProject(card)
+      : operation === 'tidy' ? store.tidyCards() : store.cardToProject(card)
     auth.beginSession()
     route = previous
     await store.refreshProjects()
@@ -268,4 +269,57 @@ describe('identity-scoped state', () => {
     expect(store.getState().projectCards).toEqual([])
     expect(store.getState().cards).toEqual([])
   })
+
+  it('does not reopen a previous account conversation after its project load finishes late', async () => {
+    projects = [ready]; tasks = [task('alice-private')]
+    await store.refreshProjects()
+    await store.openProject('another-project')
+    const old = deferred<Response>()
+    const previous = route
+    route = (path, init) => path === '/api/projects/host-1/artifacts' ? old.promise : previous(path, init)
+    const pending = store.openTask('alice-private')
+    auth.beginSession()
+    tasks = []
+    route = previous
+    await store.refreshProjects()
+    old.resolve(response([]))
+    await pending
+    expect(store.getState().currentConvId).toBeNull()
+    expect(requests.map(r => r.path)).not.toContain('/api/conversations/alice-private')
+  })
+
+  it('does not resolve old task creation as success after a new login', async () => {
+    projects = [ready]
+    await store.refreshProjects()
+    const old = deferred<Response>()
+    const previous = route
+    route = (path, init) => path === '/api/projects/host-1/conversations' ? old.promise : previous(path, init)
+    const pending = store.createTask()
+    auth.beginSession()
+    route = previous
+    await store.refreshProjects()
+    old.resolve(response(task('alice-created')))
+    await expect(pending).rejects.toThrow(/登录状态/)
+    expect(store.getState().currentConvId).toBeNull()
+  })
+
+  it('does not return a previous account attachment ID when artifact refresh finishes after login', async () => {
+    projects = [ready]
+    await store.refreshProjects()
+    const old = deferred<Response>()
+    const started = deferred<void>()
+    const previous = route
+    route = (path, init) => {
+      if (path.endsWith('/uploads')) return Promise.resolve(response({ artifactId: 'alice-upload', filename: 'alice.txt', size: 3 }))
+      if (path.endsWith('/artifacts')) { started.resolve(); return old.promise }
+      return previous(path, init)
+    }
+    const pending = store.uploadAttachment(new File(['abc'], 'alice.txt'))
+    await started.promise
+    auth.beginSession()
+    route = previous
+    await store.refreshProjects()
+    old.resolve(response([]))
+    expect(await pending).toBeNull()
+  })
 })