diff --git a/desktop/src/components/browser/BrowserSurface.test.tsx b/desktop/src/components/browser/BrowserSurface.test.tsx
index a7cbcf65..bc4feb4d 100644
--- a/desktop/src/components/browser/BrowserSurface.test.tsx
+++ b/desktop/src/components/browser/BrowserSurface.test.tsx
@@ -1,5 +1,5 @@
 import '@testing-library/jest-dom'
-import { act, cleanup, fireEvent, render, screen } from '@testing-library/react'
+import { act, cleanup, fireEvent, render, screen, waitFor, within } from '@testing-library/react'
 import { afterEach, beforeAll, describe, expect, it, vi } from 'vitest'
 
 beforeAll(() => {
@@ -22,6 +22,7 @@ import { useOverlayStore } from '../../stores/overlayStore'
 
 afterEach(() => {
   cleanup()
+  vi.restoreAllMocks()
   Object.values(bridge).forEach((f) => f.mockReset())
   useBrowserPanelStore.setState(useBrowserPanelStore.getInitialState(), true)
   // browserPanelStore.open() now also opens the unified workbench; keep it isolated.
@@ -36,6 +37,28 @@ describe('BrowserSurface', () => {
     expect(bridge.open).toHaveBeenCalledWith('http://localhost:5173/', expect.objectContaining({ width: expect.any(Number) }))
   })
 
+  it('waits for local preview URLs before opening the native preview', async () => {
+    const url = 'http://127.0.0.1:59028/preview-fs/s1/66estmutl_files/index.html'
+    const fetchSpy = vi.spyOn(globalThis, 'fetch').mockResolvedValue(new Response(null, { status: 200 }))
+    useBrowserPanelStore.getState().open('s1', url)
+    render(<BrowserSurface sessionId="s1" />)
+
+    expect(within(screen.getByTestId('preview-host')).getByLabelText('加载中')).toBeInTheDocument()
+    expect(bridge.open).not.toHaveBeenCalled()
+
+    await waitFor(() => {
+      expect(fetchSpy).toHaveBeenCalledWith(url, expect.objectContaining({
+        method: 'HEAD',
+        cache: 'no-store',
+      }))
+    })
+    await waitFor(() => {
+      expect(bridge.open).toHaveBeenCalledWith(url, expect.objectContaining({ width: expect.any(Number) }))
+    })
+
+    fetchSpy.mockRestore()
+  })
+
   it('renders an empty address bar without opening a preview for a blank session', () => {
     useBrowserPanelStore.getState().ensureBlank('s1')
     render(<BrowserSurface sessionId="s1" />)
@@ -131,7 +154,9 @@ describe('BrowserSurface', () => {
       useBrowserPanelStore.getState().open('s1', 'http://localhost:5173/')
       render(<BrowserSurface sessionId="s1" />)
       expect(useBrowserPanelStore.getState().bySession['s1']!.loading).toBe(true)
-      vi.advanceTimersByTime(15000)
+      act(() => {
+        vi.advanceTimersByTime(15000)
+      })
       expect(useBrowserPanelStore.getState().bySession['s1']!.loading).toBe(false)
     } finally {
       vi.useRealTimers()
diff --git a/desktop/src/components/browser/BrowserSurface.tsx b/desktop/src/components/browser/BrowserSurface.tsx
index 57afdd52..f3586613 100644
--- a/desktop/src/components/browser/BrowserSurface.tsx
+++ b/desktop/src/components/browser/BrowserSurface.tsx
@@ -1,14 +1,46 @@
 import { useEffect, useLayoutEffect, useRef } from 'react'
-import { Camera, MousePointer2 } from 'lucide-react'
+import { Camera, Loader2, MousePointer2 } from 'lucide-react'
 import { BrowserAddressBar } from './BrowserAddressBar'
 import { computeWebviewBounds } from './computeWebviewBounds'
+import { isLoopbackHostname } from '../../lib/desktopRuntime'
 import { previewBridge } from '../../lib/previewBridge'
 import { subscribePreviewEvents } from '../../lib/previewEvents'
 import { useBrowserPanelStore } from '../../stores/browserPanelStore'
 import { useOverlayStore } from '../../stores/overlayStore'
 
+const LOCAL_PREVIEW_PATH_PREFIXES = ['/preview-fs/', '/local-file/']
+const LOCAL_PREVIEW_READY_TIMEOUT_MS = 2500
+
+function shouldWaitForLocalPreview(url: string): boolean {
+  try {
+    const parsed = new URL(url)
+    return isLoopbackHostname(parsed.hostname) &&
+      LOCAL_PREVIEW_PATH_PREFIXES.some((prefix) => parsed.pathname.startsWith(prefix))
+  } catch {
+    return false
+  }
+}
+
+async function waitForLocalPreview(url: string): Promise<void> {
+  const controller = new AbortController()
+  const timeout = window.setTimeout(() => controller.abort(), LOCAL_PREVIEW_READY_TIMEOUT_MS)
+  try {
+    await fetch(url, {
+      method: 'HEAD',
+      cache: 'no-store',
+      signal: controller.signal,
+    })
+  } catch {
+    // Best-effort warmup only. The native webview still navigates so users can
+    // see the server's own error page or use Reload if the first probe raced.
+  } finally {
+    window.clearTimeout(timeout)
+  }
+}
+
 export function BrowserSurface({ sessionId }: { sessionId: string }) {
   const hostRef = useRef<HTMLDivElement>(null)
+  const loadSeqRef = useRef(0)
   const session = useBrowserPanelStore((s) => s.bySession[sessionId])
   const store = useBrowserPanelStore.getState()
   const overlayCount = useOverlayStore((s) => s.count)
@@ -19,12 +51,36 @@ export function BrowserSurface({ sessionId }: { sessionId: string }) {
     previewBridge.setBounds(computeWebviewBounds(el.getBoundingClientRect()))
   }
 
+  const loadNativePreview = (
+    url: string,
+    action: () => Promise<void>,
+  ) => {
+    const seq = loadSeqRef.current + 1
+    loadSeqRef.current = seq
+    void (async () => {
+      if (shouldWaitForLocalPreview(url)) {
+        await waitForLocalPreview(url)
+      }
+      if (loadSeqRef.current !== seq) return
+      await action()
+    })().catch(() => {
+      if (loadSeqRef.current === seq) {
+        useBrowserPanelStore.getState().setLoading(sessionId, false)
+      }
+    })
+  }
+
   useLayoutEffect(() => {
     const el = hostRef.current
     if (el && session?.url) {
-      previewBridge.open(session.url, computeWebviewBounds(el.getBoundingClientRect()))
+      const bounds = computeWebviewBounds(el.getBoundingClientRect())
+      const url = session.url
+      loadNativePreview(url, () => previewBridge.open(url, bounds))
+    }
+    return () => {
+      loadSeqRef.current += 1
+      previewBridge.close()
     }
-    return () => { previewBridge.close() }
     // The visibility-sync effect below owns setVisible() — including the
     // initial reveal — so it always factors in overlayCount.
     // eslint-disable-next-line react-hooks/exhaustive-deps
@@ -75,14 +131,15 @@ export function BrowserSurface({ sessionId }: { sessionId: string }) {
     const current = useBrowserPanelStore.getState().bySession[sessionId]
     store.navigate(sessionId, url)
     if (current?.url) {
-      previewBridge.navigate(url)
+      loadNativePreview(url, () => previewBridge.navigate(url))
       return
     }
     const el = hostRef.current
     if (el) {
-      previewBridge.open(url, computeWebviewBounds(el.getBoundingClientRect()))
+      const bounds = computeWebviewBounds(el.getBoundingClientRect())
+      loadNativePreview(url, () => previewBridge.open(url, bounds))
     } else {
-      previewBridge.navigate(url)
+      loadNativePreview(url, () => previewBridge.navigate(url))
     }
   }
 
@@ -135,16 +192,32 @@ export function BrowserSurface({ sessionId }: { sessionId: string }) {
         canGoForward={session.canGoForward}
         loading={session.loading}
         onNavigate={openOrNavigate}
-        onBack={() => { store.goBack(sessionId); store.setLoading(sessionId, true); previewBridge.navigate(useBrowserPanelStore.getState().bySession[sessionId]!.url) }}
-        onForward={() => { store.goForward(sessionId); store.setLoading(sessionId, true); previewBridge.navigate(useBrowserPanelStore.getState().bySession[sessionId]!.url) }}
+        onBack={() => {
+          store.goBack(sessionId)
+          store.setLoading(sessionId, true)
+          const url = useBrowserPanelStore.getState().bySession[sessionId]!.url
+          loadNativePreview(url, () => previewBridge.navigate(url))
+        }}
+        onForward={() => {
+          store.goForward(sessionId)
+          store.setLoading(sessionId, true)
+          const url = useBrowserPanelStore.getState().bySession[sessionId]!.url
+          loadNativePreview(url, () => previewBridge.navigate(url))
+        }}
         onReload={() => {
           if (!session.url) return
           store.setLoading(sessionId, true)
-          previewBridge.navigate(session.url)
+          loadNativePreview(session.url, () => previewBridge.navigate(session.url))
         }}
         rightActions={previewActions}
       />
-      <div ref={hostRef} className="flex-1" data-testid="preview-host" />
+      <div ref={hostRef} className="relative flex-1 overflow-hidden" data-testid="preview-host">
+        {session.loading && (
+          <div className="pointer-events-none absolute inset-0 flex items-center justify-center bg-[var(--color-surface)] text-[var(--color-text-tertiary)]">
+            <Loader2 size={18} className="animate-spin" aria-label="加载中" />
+          </div>
+        )}
+      </div>
     </div>
   )
 }
diff --git a/desktop/src/components/common/OpenWithMenu.test.tsx b/desktop/src/components/common/OpenWithMenu.test.tsx
index a2481163..0a8103c4 100644
--- a/desktop/src/components/common/OpenWithMenu.test.tsx
+++ b/desktop/src/components/common/OpenWithMenu.test.tsx
@@ -69,6 +69,13 @@ describe('OpenWithMenu', () => {
     expect(onClose).toHaveBeenCalledTimes(1)
   })
 
+  it('scrolling the viewport calls onClose', () => {
+    const onClose = vi.fn()
+    render(<OpenWithMenu items={makeItems()} anchor={anchor} onClose={onClose} />)
+    fireEvent.scroll(window)
+    expect(onClose).toHaveBeenCalledTimes(1)
+  })
+
   describe('triggerEl exclusion (re-click-trigger toggle support)', () => {
     it('does NOT call onClose when mousedown lands inside triggerEl', () => {
       // Set up a trigger element + a child within it in the document.
diff --git a/desktop/src/components/common/OpenWithMenu.tsx b/desktop/src/components/common/OpenWithMenu.tsx
index ae1f75de..340dd6a8 100644
--- a/desktop/src/components/common/OpenWithMenu.tsx
+++ b/desktop/src/components/common/OpenWithMenu.tsx
@@ -61,9 +61,17 @@ export function OpenWithMenu({ items, anchor, onClose, triggerEl }: Props) {
       onClose()
     }
     const onKey = (e: KeyboardEvent) => { if (e.key === 'Escape') onClose() }
+    const onViewportMove = () => onClose()
     document.addEventListener('mousedown', onDown)
     document.addEventListener('keydown', onKey)
-    return () => { document.removeEventListener('mousedown', onDown); document.removeEventListener('keydown', onKey) }
+    window.addEventListener('scroll', onViewportMove, true)
+    window.addEventListener('resize', onViewportMove)
+    return () => {
+      document.removeEventListener('mousedown', onDown)
+      document.removeEventListener('keydown', onKey)
+      window.removeEventListener('scroll', onViewportMove, true)
+      window.removeEventListener('resize', onViewportMove)
+    }
   }, [onClose, triggerEl])
 
   return createPortal(
diff --git a/desktop/src/components/workspace/WorkspaceFileOpenWith.test.tsx b/desktop/src/components/workspace/WorkspaceFileOpenWith.test.tsx
index 000284bb..0d7300cb 100644
--- a/desktop/src/components/workspace/WorkspaceFileOpenWith.test.tsx
+++ b/desktop/src/components/workspace/WorkspaceFileOpenWith.test.tsx
@@ -7,6 +7,8 @@ import { browserHost } from '../../lib/desktopHost/browserHost'
 const openTarget = vi.hoisted(() => vi.fn())
 const shellOpen = vi.hoisted(() => vi.fn().mockResolvedValue(undefined))
 const hostOpenPath = vi.hoisted(() => vi.fn().mockResolvedValue(undefined))
+const browserOpen = vi.hoisted(() => vi.fn())
+const openPreview = vi.hoisted(() => vi.fn().mockResolvedValue(undefined))
 
 vi.mock('../../stores/openTargetStore', () => ({
   useOpenTargetStore: (sel: (s: unknown) => unknown) =>
@@ -27,6 +29,18 @@ vi.mock('../../i18n', () => ({
     v?.target ? `${k}:${v.target}` : k,
 }))
 
+vi.mock('../../stores/browserPanelStore', () => ({
+  useBrowserPanelStore: {
+    getState: () => ({ open: browserOpen }),
+  },
+}))
+
+vi.mock('../../stores/workspacePanelStore', () => ({
+  useWorkspacePanelStore: {
+    getState: () => ({ openPreview }),
+  },
+}))
+
 import { WorkspaceFileOpenWith } from './WorkspaceFileOpenWith'
 
 describe('WorkspaceFileOpenWith', () => {
@@ -82,4 +96,60 @@ describe('WorkspaceFileOpenWith', () => {
     expect(shellOpen).not.toHaveBeenCalled()
     expect(hostOpenPath).not.toHaveBeenCalled()
   })
+
+  it('offers workspace preview and in-app browser for generated html files with session context', () => {
+    const { getAllByRole } = render(
+      <WorkspaceFileOpenWith
+        absolutePath="/w/66estmutl_files/index.html"
+        sessionId="s1"
+        workspacePath="66estmutl_files/index.html"
+      />,
+    )
+
+    const menuItems = getAllByRole('menuitem')
+    const labels = menuItems.map((el) => el.textContent)
+    expect(labels.some((l) => l?.includes('openWith.workspacePreview'))).toBe(true)
+    expect(labels.some((l) => l?.includes('openWith.inAppBrowser'))).toBe(true)
+    expect(labels.some((l) => l?.includes('VS Code'))).toBe(true)
+    expect(labels.some((l) => l?.includes('Finder'))).toBe(true)
+  })
+
+  it('opens the in-app browser preview URL from workspace html files', () => {
+    const { getAllByRole } = render(
+      <WorkspaceFileOpenWith
+        absolutePath="/w/66estmutl_files/index.html"
+        sessionId="s1"
+        workspacePath="66estmutl_files/index.html"
+      />,
+    )
+
+    const menuItems = getAllByRole('menuitem')
+    const inAppItem = menuItems.find((el) => el.textContent?.includes('openWith.inAppBrowser'))
+    if (!inAppItem) throw new Error('In-app browser menu item not found')
+
+    fireEvent.click(inAppItem)
+
+    expect(browserOpen).toHaveBeenCalledWith(
+      's1',
+      'http://127.0.0.1:3456/preview-fs/s1/66estmutl_files/index.html',
+    )
+  })
+
+  it('opens the workspace preview for workspace files with session context', () => {
+    const { getAllByRole } = render(
+      <WorkspaceFileOpenWith
+        absolutePath="/w/report.md"
+        sessionId="s1"
+        workspacePath="report.md"
+      />,
+    )
+
+    const menuItems = getAllByRole('menuitem')
+    const previewItem = menuItems.find((el) => el.textContent?.includes('openWith.workspacePreview'))
+    if (!previewItem) throw new Error('Workspace preview menu item not found')
+
+    fireEvent.click(previewItem)
+
+    expect(openPreview).toHaveBeenCalledWith('s1', 'report.md', 'file')
+  })
 })
diff --git a/desktop/src/components/workspace/WorkspaceFileOpenWith.tsx b/desktop/src/components/workspace/WorkspaceFileOpenWith.tsx
index 8a481d4b..cabcdbb2 100644
--- a/desktop/src/components/workspace/WorkspaceFileOpenWith.tsx
+++ b/desktop/src/components/workspace/WorkspaceFileOpenWith.tsx
@@ -4,6 +4,10 @@ import { useTranslation, type TranslationKey } from '../../i18n'
 import { useOpenTargetStore } from '../../stores/openTargetStore'
 import { buildOpenWithItems, type OpenWithItem, type OpenWithDeps } from '../../lib/openWithItems'
 import { getDesktopHost } from '../../lib/desktopHost'
+import { getServerBaseUrl } from '../../lib/desktopRuntime'
+import { openWithContextForWorkspaceFile } from '../../lib/openWithContextForHref'
+import { useBrowserPanelStore } from '../../stores/browserPanelStore'
+import { useWorkspacePanelStore } from '../../stores/workspacePanelStore'
 import { TargetIcon } from '../common/TargetIcon'
 
 function openExternal(path: string) {
@@ -12,9 +16,13 @@ function openExternal(path: string) {
 
 export function WorkspaceFileOpenWith({
   absolutePath,
+  sessionId,
+  workspacePath,
   onAfterSelect,
 }: {
   absolutePath: string
+  sessionId?: string
+  workspacePath?: string
   onAfterSelect?: () => void
 }) {
   const t = useTranslation()
@@ -30,8 +38,14 @@ export function WorkspaceFileOpenWith({
   // but OpenWithDeps.t expects (key: string, vars?: Record<string, string>) => string.
   // All keys buildOpenWithItems calls are valid TranslationKeys, so the cast is safe.
   const deps: OpenWithDeps = {
-    openInAppBrowser: () => {},
-    openWorkspacePreview: () => {},
+    openInAppBrowser: (url) => {
+      if (!sessionId) return
+      useBrowserPanelStore.getState().open(sessionId, url)
+    },
+    openWorkspacePreview: (relPath) => {
+      if (!sessionId) return
+      void useWorkspacePanelStore.getState().openPreview(sessionId, relPath, 'file')
+    },
     openSystem: (p) => openExternal(p),
     openTarget: (id, p) => {
       void openTarget(id, p)
@@ -39,7 +53,12 @@ export function WorkspaceFileOpenWith({
     t: (key, vars) => t(key as TranslationKey, vars),
   }
   const items: OpenWithItem[] = buildOpenWithItems(
-    { kind: 'file', absolutePath, previewable: false },
+    sessionId && workspacePath
+      ? openWithContextForWorkspaceFile(workspacePath, absolutePath, {
+        sessionId,
+        serverBaseUrl: getServerBaseUrl(),
+      })
+      : { kind: 'file', absolutePath, previewable: false },
     targets,
     deps,
   )
diff --git a/desktop/src/components/workspace/WorkspacePanel.tsx b/desktop/src/components/workspace/WorkspacePanel.tsx
index 7939528f..5e42bb08 100644
--- a/desktop/src/components/workspace/WorkspacePanel.tsx
+++ b/desktop/src/components/workspace/WorkspacePanel.tsx
@@ -1516,6 +1516,8 @@ export function WorkspacePanel({ sessionId, embedded = false }: WorkspacePanelPr
           </button>
           <WorkspaceFileOpenWith
             absolutePath={resolveWorkspaceAttachmentPath(status?.workDir, fileContextMenu.path)}
+            sessionId={sessionId}
+            workspacePath={fileContextMenu.isDirectory ? undefined : fileContextMenu.path}
             onAfterSelect={() => setFileContextMenu(null)}
           />
         </div>
diff --git a/desktop/src/lib/handlePreviewLink.test.ts b/desktop/src/lib/handlePreviewLink.test.ts
index 78d55496..46c25f2a 100644
--- a/desktop/src/lib/handlePreviewLink.test.ts
+++ b/desktop/src/lib/handlePreviewLink.test.ts
@@ -64,6 +64,17 @@ describe('handlePreviewLink', () => {
     expect(deps.openFilePreview).not.toHaveBeenCalled()
   })
 
+  it('routes generated *_files index.html to openBrowser with the preview-fs url', () => {
+    const deps = makeDeps()
+    const handled = handlePreviewLink('66estmutl_files/index.html', deps)
+    expect(handled).toBe(true)
+    expect(deps.openBrowser).toHaveBeenCalledWith(
+      's1',
+      'http://127.0.0.1:8787/preview-fs/s1/66estmutl_files/index.html',
+    )
+    expect(deps.openFilePreview).not.toHaveBeenCalled()
+  })
+
   it('routes a frontend project index.html to workspace preview instead of static browser preview', () => {
     const deps = makeDeps()
     const handled = handlePreviewLink('todo-app/index.html', deps)
diff --git a/desktop/src/lib/htmlPreviewPolicy.ts b/desktop/src/lib/htmlPreviewPolicy.ts
index fa81dd1e..773b5741 100644
--- a/desktop/src/lib/htmlPreviewPolicy.ts
+++ b/desktop/src/lib/htmlPreviewPolicy.ts
@@ -1,5 +1,6 @@
 const HTML_EXT = /\.(html?|xhtml)$/i
 const INDEX_HTML_RE = /(^|\/)index\.html?$/i
+const GENERATED_STATIC_FILES_DIR_RE = /(^|\/)[^/]+_files\/index\.html?$/i
 
 const STATIC_OUTPUT_DIRS = new Set([
   'build',
@@ -28,6 +29,7 @@ export function shouldOfferStaticHtmlPreview(filePath: string): boolean {
   const normalized = normalizePathForPolicy(filePath)
   if (!HTML_EXT.test(normalized)) return false
   if (!INDEX_HTML_RE.test(normalized)) return true
+  if (GENERATED_STATIC_FILES_DIR_RE.test(normalized)) return true
 
   return normalized
     .split('/')
diff --git a/desktop/src/lib/openWithContextForHref.test.ts b/desktop/src/lib/openWithContextForHref.test.ts
index 436e01ca..b294c0f6 100644
--- a/desktop/src/lib/openWithContextForHref.test.ts
+++ b/desktop/src/lib/openWithContextForHref.test.ts
@@ -68,6 +68,17 @@ describe('openWithContextForWorkspaceFile', () => {
     })
   })
 
+  it('generated *_files index.html rel path → has inAppBrowserUrl equal to previewFsUrl', () => {
+    const result = openWithContextForWorkspaceFile('66estmutl_files/index.html', '/w/proj/66estmutl_files/index.html', { sessionId: SESSION, serverBaseUrl: BASE })
+    expect(result).toEqual({
+      kind: 'file',
+      absolutePath: '/w/proj/66estmutl_files/index.html',
+      relPath: '66estmutl_files/index.html',
+      previewable: true,
+      inAppBrowserUrl: previewFsUrl(BASE, SESSION, '66estmutl_files/index.html'),
+    })
+  })
+
   it('built dist index.html rel path → has inAppBrowserUrl equal to previewFsUrl', () => {
     const result = openWithContextForWorkspaceFile('todo-app/dist/index.html', '/w/proj/todo-app/dist/index.html', { sessionId: SESSION, serverBaseUrl: BASE })
     expect(result).toEqual({