diff --git a/src/components/Workbench.tsx b/src/components/Workbench.tsx
index 39efbd4..bfdcc2a 100644
--- a/src/components/Workbench.tsx
+++ b/src/components/Workbench.tsx
@@ -1,7 +1,6 @@
 // 右栏（第三栏）：「工作 / 文件」双入口。
 // 工作 = 当前任务卡 + 收件箱（待处理事项、后台任务卡、执行记录）；
 // 文件 = 文件列表（搜索/上传）与多标签预览（预览、编辑、下载）——预览不再是独立第四栏。
-import { api } from '../api'
 import { store, useStore } from '../store'
 import type { Run } from '../contracts'
 import { InboxList, pendingCount, type ActivityCard, type DocBridge, type InboxFilter } from '@ui'
@@ -14,15 +13,7 @@ import { PreviewPane } from './PreviewPane'
 // 工件解析/打开注入：渲染器纯展示，doc-ref 词汇经此桥接本仓状态（D29）。
 // 打开语义走 requestPreview 唯一入口（第三栏「文件」入口）。
 export const docBridge: DocBridge = {
-  onOpenTaskSource: async (cardId,source)=>{
-    const context=store.getState().currentConvId,project=store.getState().currentProjectId
-    try{const out=await api.taskSource(cardId,source.id)
-      if(context!==store.getState().currentConvId||project!==store.getState().currentProjectId)return
-      if(!out.artifact){store.toast('来源当前不可用，正在核实工作记录');if(context)void store.refreshCards(context);return}
-      store.requestTaskSourcePreview(out.artifact,{notice:out.versionState==='changed'?'当前文件已更新；下方引用来自任务处理时的版本，不能作为当前文件的结论':'任务处理时引用的来源版本；下方是本项发现引用的片段',quote:out.source.quote??'',expectedHash:out.versionState==='current'?out.source.contentHash:undefined})
-      if(out.versionState==='changed'&&context)void store.refreshCards(context)
-    }catch{if(context===store.getState().currentConvId&&project===store.getState().currentProjectId){store.toast('来源当前无法读取，正在核实工作记录');if(context)void store.refreshCards(context)}}
-  },
+  onOpenTaskSource: (cardId, source) => store.openTaskSource(cardId, source),
   resolveDoc: id => store.getState().artifacts.find(a => a.id === id),
   onOpenDoc: id => {
     const art = store.getState().artifacts.find(a => a.id === id)
diff --git a/src/store.ts b/src/store.ts
index 6506b1a..e9142aa 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -20,6 +20,7 @@ export function isFontSizeChoice(value: number): value is FontSizeChoice {
 }
 import type {
   ActivityCard,
+  TaskSourceRef,
   AgentProfile,
   Artifact,
   Conversation,
@@ -218,7 +219,8 @@ function syncFilesEntry(hasTabs: boolean) {
 
 function setUI(patch: Partial<UIState>) {
   const ui = { ...state.ui, ...patch }
-  state = { ...state, ui }
+  const navigation=(['rightTab','filesView','rightCollapsed','activeWorkspace'] as const).some(key=>key in patch&&patch[key]!==state.ui[key])
+  state = { ...state, ui,previewOpenIntent:state.previewOpenIntent+(navigation?1:0) }
   try { localStorage.setItem('as.ui', JSON.stringify(ui)) } catch { /* ignore */ }
   applyTheme(ui.theme)
   applyFontSize(ui.fontSize)
@@ -1255,6 +1257,36 @@ export const store = {
    * 工件预览唯一入口：在第三栏「文件」入口打开或激活标签（多文件多标签）。
    * 打开第一张自动切到预览子视图；关掉最后一张回到文件列表，并收回展开态。
    */
+  async openTaskSource(cardId: string, source: TaskSourceRef) {
+    const conversationId = state.currentConvId
+    const projectId = state.currentProjectId
+    const epoch = conversationEpoch
+    const intent = state.previewOpenIntent + 1
+    set({ previewOpenIntent: intent })
+    const isCurrent = () => conversationId === state.currentConvId && projectId === state.currentProjectId
+      && epoch === conversationEpoch && intent === state.previewOpenIntent
+    try {
+      const out = await api.taskSource(cardId, source.id)
+      if (!isCurrent()) return
+      if (!out.artifact) {
+        store.toast('来源当前不可用，正在核实工作记录')
+        if (conversationId) void store.refreshCards(conversationId)
+        return
+      }
+      store.requestTaskSourcePreview(out.artifact, {
+        notice: out.versionState === 'changed'
+          ? '当前文件已更新；下方引用来自任务处理时的版本，不能作为当前文件的结论'
+          : '任务处理时引用的来源版本；下方是本项发现引用的片段',
+        quote: out.source.quote ?? '',
+        expectedHash: out.versionState === 'current' ? out.source.contentHash : undefined,
+      })
+      if (out.versionState === 'changed' && conversationId) void store.refreshCards(conversationId)
+    } catch {
+      if (!isCurrent()) return
+      store.toast('来源当前无法读取，正在核实工作记录')
+      if (conversationId) void store.refreshCards(conversationId)
+    }
+  },
   requestTaskSourcePreview(a:Artifact,sourceContext:{notice:string;quote:string;expectedHash?:string}){
     store.requestPreview(a)
     const conv=previewTabsKey(state.currentConvId)
@@ -1311,7 +1343,7 @@ export const store = {
   togglePreviewExpanded() { setUI({ previewExpanded: !state.ui.previewExpanded }) },
   activatePreview(id: string) {
     const conv = previewTabsKey(state.currentConvId)
-    set({ previewActive: { ...state.previewActive, [conv]: id } })
+    set({ previewActive: { ...state.previewActive, [conv]: id },previewOpenIntent:state.previewOpenIntent+1 })
   },
   closePreview(id: string) {
     const conv = previewTabsKey(state.currentConvId)
@@ -1319,6 +1351,7 @@ export const store = {
     set({
       previewTabs: { ...state.previewTabs, [conv]: next.tabs },
       previewActive: { ...state.previewActive, [conv]: next.activeId },
+      previewOpenIntent:state.previewOpenIntent+1,
     })
     if (next.tabs.length === 0) setUI({ previewExpanded: false })
     syncFilesEntry(next.tabs.length > 0)
diff --git a/test/work-state.test.ts b/test/work-state.test.ts
index 1a5186a..2e7d539 100644
--- a/test/work-state.test.ts
+++ b/test/work-state.test.ts
@@ -443,3 +443,38 @@ it('rejects old revisions and foreign attempts in the task merge contract',()=>{
  expect(mergeTaskSnapshot({taskId:'t',attemptId:'a',revision:9},{taskId:'t',attemptId:'a',revision:8}).revision).toBe(9)
  expect(mergeTaskSnapshot({taskId:'t',attemptId:'a',revision:9},{taskId:'t',attemptId:'b',revision:10}).attemptId).toBe('a')
 })
+
+it('keeps the newer explicit preview when a source response arrives late',async()=>{
+ const source={id:'s',artifactId:'a',contentHash:'hash',parserRevision:'v1',blockIndex:0,label:'A'}
+ const pending=deferred<Awaited<ReturnType<typeof api.taskSource>>>()
+ vi.spyOn(api,'taskSource').mockReturnValue(pending.promise)
+ const {docBridge}=await import('../src/components/Workbench')
+ const opening=docBridge.onOpenTaskSource!('card',source)
+ store.requestPreview({id:'b',name:'B',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0})
+ pending.resolve({artifact:{id:'a',name:'A',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0},source,versionState:'current'})
+ await opening
+ expect(store.getState().previewActive.a).toBe('b')
+})
+
+it('rejects a source response after leaving and returning to the same conversation',async()=>{
+ const source={id:'s',artifactId:'a',contentHash:'hash',parserRevision:'v1',blockIndex:0,label:'A'}
+ const pending=deferred<Awaited<ReturnType<typeof api.taskSource>>>()
+ vi.spyOn(api,'taskSource').mockReturnValue(pending.promise)
+ const opening=store.openTaskSource('card',source)
+ await store.openConversation('b');await store.openConversation('a')
+ store.requestPreview({id:'new',name:'New',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0})
+ pending.resolve({artifact:{id:'a',name:'A',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0},source,versionState:'current'})
+ await opening
+ expect(store.getState().previewActive.a).toBe('new')
+})
+it('keeps the activated tab when a source request is still pending',async()=>{
+ store.requestPreview({id:'b',name:'B',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0})
+ store.requestPreview({id:'c',name:'C',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0})
+ const source={id:'s',artifactId:'a',contentHash:'hash',parserRevision:'v1',blockIndex:0,label:'A'}
+ const pending=deferred<Awaited<ReturnType<typeof api.taskSource>>>()
+ vi.spyOn(api,'taskSource').mockReturnValue(pending.promise)
+ const opening=store.openTaskSource('card',source);store.activatePreview('b')
+ pending.resolve({artifact:{id:'a',name:'A',kind:'document',projectId:'p',createdAt:'',updatedAt:'',size:0},source,versionState:'current'})
+ await opening
+ expect(store.getState().previewActive.a).toBe('b')
+})