diff --git a/desktop/src/components/chat/CurrentTurnChangeCard.test.tsx b/desktop/src/components/chat/CurrentTurnChangeCard.test.tsx
new file mode 100644
index 00000000..3792e2e4
--- /dev/null
+++ b/desktop/src/components/chat/CurrentTurnChangeCard.test.tsx
@@ -0,0 +1,211 @@
+import '@testing-library/jest-dom'
+import { describe, expect, it, vi, beforeEach } from 'vitest'
+import { render, screen, fireEvent } from '@testing-library/react'
+import { act } from 'react'
+
+// ──────────────────────────────────────────────────────────────────────────────
+// Hoisted mocks (vi.hoisted runs before module evaluation)
+// ──────────────────────────────────────────────────────────────────────────────
+const { openPreviewSpy, browserOpenSpy, openTargetSpy, ensureTargetsMock } = vi.hoisted(() => {
+  const openPreviewSpy = vi.fn().mockResolvedValue(undefined)
+  const browserOpenSpy = vi.fn()
+  const openTargetSpy = vi.fn().mockResolvedValue(undefined)
+  const ensureTargetsMock = vi.fn().mockResolvedValue(undefined)
+  return { openPreviewSpy, browserOpenSpy, openTargetSpy, ensureTargetsMock }
+})
+
+// Mock sessionsApi so diff calls don't run
+vi.mock('../../api/sessions', () => ({
+  sessionsApi: {
+    getTurnCheckpointDiff: vi.fn().mockResolvedValue({ state: 'ok', diff: '--- a\n+++ b\n@@ -0,0 +1 @@\n+hello' }),
+  },
+}))
+
+// Mock openTargetStore
+vi.mock('../../stores/openTargetStore', () => ({
+  useOpenTargetStore: Object.assign(
+    // Selector hook form: useOpenTargetStore((s) => s.xxx)
+    (selector: (s: { targets: unknown[]; ensureTargets: () => Promise<void>; openTarget: () => Promise<void> }) => unknown) =>
+      selector({
+        targets: [{ id: 'code', kind: 'ide', label: 'VS Code', icon: '', platform: 'darwin' }],
+        ensureTargets: ensureTargetsMock,
+        openTarget: openTargetSpy,
+      }),
+    {
+      // Static .getState() access
+      getState: vi.fn(() => ({
+        targets: [{ id: 'code', kind: 'ide', label: 'VS Code', icon: '', platform: 'darwin' }],
+        ensureTargets: ensureTargetsMock,
+        openTarget: openTargetSpy,
+      })),
+    },
+  ),
+}))
+
+// Mock browserPanelStore
+vi.mock('../../stores/browserPanelStore', () => ({
+  useBrowserPanelStore: Object.assign(
+    (selector: (s: { open: () => void }) => unknown) =>
+      selector({ open: browserOpenSpy }),
+    {
+      getState: vi.fn(() => ({ open: browserOpenSpy })),
+    },
+  ),
+}))
+
+// Mock workspacePanelStore
+vi.mock('../../stores/workspacePanelStore', () => ({
+  useWorkspacePanelStore: Object.assign(
+    (selector: (s: { openPreview: () => Promise<void> }) => unknown) =>
+      selector({ openPreview: openPreviewSpy }),
+    {
+      getState: vi.fn(() => ({ openPreview: openPreviewSpy })),
+    },
+  ),
+}))
+
+// Mock @tauri-apps/plugin-shell
+vi.mock('@tauri-apps/plugin-shell', () => ({
+  open: vi.fn().mockResolvedValue(undefined),
+}))
+
+// Mock desktopRuntime.getServerBaseUrl
+vi.mock('../../lib/desktopRuntime', () => ({
+  getServerBaseUrl: vi.fn(() => 'http://127.0.0.1:4321'),
+}))
+
+// Mock useTranslation: returns identity-ish t function
+vi.mock('../../i18n', () => ({
+  useTranslation: () => (key: string, params?: Record<string, string | number>) => {
+    if (params) {
+      return Object.entries(params).reduce<string>(
+        (acc, [k, v]) => acc.replace(`{${k}}`, String(v)),
+        key,
+      )
+    }
+    return key
+  },
+}))
+
+// ──────────────────────────────────────────────────────────────────────────────
+// Import after mocks
+// ──────────────────────────────────────────────────────────────────────────────
+import { CurrentTurnChangeCard } from './CurrentTurnChangeCard'
+import type { SessionTurnCheckpoint } from '../../api/sessions'
+
+// ──────────────────────────────────────────────────────────────────────────────
+// Helpers
+// ──────────────────────────────────────────────────────────────────────────────
+function makeCheckpoint(filesChanged: string[]): SessionTurnCheckpoint {
+  return {
+    code: {
+      available: true,
+      filesChanged,
+      insertions: 10,
+      deletions: 0,
+    },
+    target: {
+      targetUserMessageId: 'msg-1',
+      userMessageIndex: 0,
+      userMessageCount: 1,
+    },
+    conversation: {
+      messagesRemoved: 0,
+    },
+  }
+}
+
+function renderCard(filesChanged: string[]) {
+  const checkpoint = makeCheckpoint(filesChanged)
+  return render(
+    <CurrentTurnChangeCard
+      sessionId="s1"
+      targetUserMessageId="msg-1"
+      checkpoint={checkpoint}
+      workDir="/w/proj"
+      error={null}
+      isUndoing={false}
+      isLatest={true}
+      onUndo={vi.fn()}
+    />,
+  )
+}
+
+// ──────────────────────────────────────────────────────────────────────────────
+// Tests
+// ──────────────────────────────────────────────────────────────────────────────
+describe('CurrentTurnChangeCard – open-with buttons', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    ensureTargetsMock.mockResolvedValue(undefined)
+    openPreviewSpy.mockResolvedValue(undefined)
+  })
+
+  it('renders one "open-with" button per file', () => {
+    renderCard(['/w/proj/README.md', '/w/proj/index.html'])
+    // aria-label is the i18n key itself (identity mock)
+    const buttons = screen.getAllByRole('button', { name: 'openWith.title' })
+    expect(buttons).toHaveLength(2)
+  })
+
+  it('clicking README.md open-with opens menu with workspace preview item', async () => {
+    renderCard(['/w/proj/README.md'])
+    const [openWithBtn] = screen.getAllByRole('button', { name: 'openWith.title' })
+
+    await act(async () => {
+      fireEvent.click(openWithBtn!)
+    })
+
+    // The menu should show a workspace preview item (i18n key)
+    expect(await screen.findByText('openWith.workspacePreview')).toBeInTheDocument()
+  })
+
+  it('clicking workspace preview item in README.md menu calls openPreview', async () => {
+    renderCard(['/w/proj/README.md'])
+    const [openWithBtn] = screen.getAllByRole('button', { name: 'openWith.title' })
+
+    await act(async () => {
+      fireEvent.click(openWithBtn!)
+    })
+
+    const previewItem = await screen.findByText('openWith.workspacePreview')
+    await act(async () => {
+      fireEvent.click(previewItem)
+    })
+
+    expect(openPreviewSpy).toHaveBeenCalledWith('s1', 'README.md', 'file')
+  })
+
+  it('clicking index.html open-with opens menu with in-app browser item', async () => {
+    renderCard(['/w/proj/index.html'])
+    const [openWithBtn] = screen.getAllByRole('button', { name: 'openWith.title' })
+
+    await act(async () => {
+      fireEvent.click(openWithBtn!)
+    })
+
+    expect(await screen.findByText('openWith.inAppBrowser')).toBeInTheDocument()
+  })
+
+  it('ensureTargets is called when open-with button is clicked', async () => {
+    renderCard(['/w/proj/README.md'])
+    const [openWithBtn] = screen.getAllByRole('button', { name: 'openWith.title' })
+
+    await act(async () => {
+      fireEvent.click(openWithBtn!)
+    })
+
+    expect(ensureTargetsMock).toHaveBeenCalledTimes(1)
+  })
+
+  it('diff-toggle button still works (not nested button regression)', async () => {
+    renderCard(['/w/proj/README.md'])
+    // The diff toggle has aria-label from the i18n key + path
+    const diffBtn = screen.getByRole('button', { name: /turnChangesShowDiffAria/ })
+    expect(diffBtn).toBeInTheDocument()
+    // Clicking should not throw
+    await act(async () => {
+      fireEvent.click(diffBtn)
+    })
+  })
+})
diff --git a/desktop/src/components/chat/CurrentTurnChangeCard.tsx b/desktop/src/components/chat/CurrentTurnChangeCard.tsx
index dd4457cc..8405fed6 100644
--- a/desktop/src/components/chat/CurrentTurnChangeCard.tsx
+++ b/desktop/src/components/chat/CurrentTurnChangeCard.tsx
@@ -1,7 +1,15 @@
 import { useCallback, useMemo, useState } from 'react'
+import type { MouseEvent as ReactMouseEvent } from 'react'
 import { sessionsApi, type SessionTurnCheckpoint } from '../../api/sessions'
-import { useTranslation } from '../../i18n'
+import { useTranslation, type TranslationKey } from '../../i18n'
 import { WorkspaceDiffSurface } from '../workspace/WorkspaceCodeSurface'
+import { OpenWithMenu } from '../common/OpenWithMenu'
+import { buildOpenWithItems, type OpenWithItem } from '../../lib/openWithItems'
+import { openWithContextForWorkspaceFile } from '../../lib/openWithContextForHref'
+import { getServerBaseUrl } from '../../lib/desktopRuntime'
+import { useOpenTargetStore } from '../../stores/openTargetStore'
+import { useBrowserPanelStore } from '../../stores/browserPanelStore'
+import { useWorkspacePanelStore } from '../../stores/workspacePanelStore'
 
 type DiffPreviewState = {
   loading: boolean
@@ -38,6 +46,7 @@ export function CurrentTurnChangeCard({
   const t = useTranslation()
   const [expandedPath, setExpandedPath] = useState<string | null>(null)
   const [diffByPath, setDiffByPath] = useState<Record<string, DiffPreviewState>>({})
+  const [openWith, setOpenWith] = useState<{ items: OpenWithItem[]; anchor: DOMRect } | null>(null)
 
   const files = useMemo<ChangedFileEntry[]>(
     () => checkpoint.code.filesChanged.map((filePath) => ({
@@ -91,6 +100,27 @@ export function CurrentTurnChangeCard({
       })
   }, [diffByPath, expandedPath, sessionId, t, targetUserMessageId])
 
+  const handleOpenWith = useCallback((event: ReactMouseEvent<HTMLButtonElement>, fileEntry: ChangedFileEntry) => {
+    event.stopPropagation()
+    const rect = event.currentTarget.getBoundingClientRect()
+    void (async () => {
+      await useOpenTargetStore.getState().ensureTargets()
+      const targets = useOpenTargetStore.getState().targets
+      const ctx = openWithContextForWorkspaceFile(fileEntry.displayPath, fileEntry.apiPath, {
+        sessionId,
+        serverBaseUrl: getServerBaseUrl(),
+      })
+      const items = buildOpenWithItems(ctx, targets, {
+        openInAppBrowser: (url) => useBrowserPanelStore.getState().open(sessionId, url),
+        openSystem: (p) => { void import('@tauri-apps/plugin-shell').then((m) => m.open(p)).catch(() => {}) },
+        openWorkspacePreview: (rel) => { void useWorkspacePanelStore.getState().openPreview(sessionId, rel, 'file') },
+        openTarget: (id, abs) => { void useOpenTargetStore.getState().openTarget(id, abs) },
+        t: (k, v) => t(k as TranslationKey, v),
+      })
+      setOpenWith({ items, anchor: rect })
+    })()
+  }, [sessionId, t])
+
   const cardLabel = isLatest
     ? t('chat.turnChangesLatestCardLabel')
     : t('chat.turnChangesHistoricalCardLabel')
@@ -145,22 +175,32 @@ export function CurrentTurnChangeCard({
           const diffState = diffByPath[fileEntry.apiPath]
           return (
             <div key={fileEntry.apiPath}>
-              <button
-                type="button"
-                onClick={() => toggleDiff(fileEntry)}
-                aria-label={t(
-                  isExpanded ? 'chat.turnChangesHideDiffAria' : 'chat.turnChangesShowDiffAria',
-                  { path: fileEntry.displayPath },
-                )}
-                className="flex min-h-11 w-full items-center gap-3 px-4 text-left text-sm text-[var(--color-text-primary)] transition-colors hover:bg-[var(--color-surface-hover)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-[var(--color-brand)]/35"
-              >
-                <span className="material-symbols-outlined shrink-0 text-[17px] text-[var(--color-text-tertiary)]">
-                  {isExpanded ? 'keyboard_arrow_down' : 'chevron_right'}
-                </span>
-                <span className="min-w-0 flex-1 truncate font-mono text-[13px]">
-                  {fileEntry.displayPath}
-                </span>
-              </button>
+              <div className="flex items-center">
+                <button
+                  type="button"
+                  onClick={() => toggleDiff(fileEntry)}
+                  aria-label={t(
+                    isExpanded ? 'chat.turnChangesHideDiffAria' : 'chat.turnChangesShowDiffAria',
+                    { path: fileEntry.displayPath },
+                  )}
+                  className="flex min-h-11 flex-1 items-center gap-3 px-4 text-left text-sm text-[var(--color-text-primary)] transition-colors hover:bg-[var(--color-surface-hover)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-[var(--color-brand)]/35"
+                >
+                  <span className="material-symbols-outlined shrink-0 text-[17px] text-[var(--color-text-tertiary)]">
+                    {isExpanded ? 'keyboard_arrow_down' : 'chevron_right'}
+                  </span>
+                  <span className="min-w-0 flex-1 truncate font-mono text-[13px]">
+                    {fileEntry.displayPath}
+                  </span>
+                </button>
+                <button
+                  type="button"
+                  aria-label={t('openWith.title')}
+                  onClick={(event) => handleOpenWith(event, fileEntry)}
+                  className="mr-2 inline-flex h-8 w-8 shrink-0 items-center justify-center rounded-[var(--radius-md)] text-[var(--color-text-tertiary)] hover:bg-[var(--color-surface-hover)] hover:text-[var(--color-text-primary)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-brand)]/35"
+                >
+                  <span className="material-symbols-outlined text-[18px]">open_in_new</span>
+                </button>
+              </div>
 
               {isExpanded && (
                 <div className="border-t border-[var(--color-border)] bg-[var(--color-surface-container-lowest)] px-4 py-3">
@@ -195,6 +235,8 @@ export function CurrentTurnChangeCard({
           {error}
         </div>
       )}
+
+      {openWith && <OpenWithMenu items={openWith.items} anchor={openWith.anchor} onClose={() => setOpenWith(null)} />}
     </section>
   )
 }
diff --git a/desktop/src/i18n/locales/en.ts b/desktop/src/i18n/locales/en.ts
index b61c9928..7bd485a3 100644
--- a/desktop/src/i18n/locales/en.ts
+++ b/desktop/src/i18n/locales/en.ts
@@ -92,6 +92,7 @@ export const en = {
   'openProject.openFailed': 'Could not open project',
 
   // ─── Open With ─────────────────────────────────────
+  'openWith.title': 'Open with',
   'openWith.inAppBrowser': 'In-app browser',
   'openWith.systemBrowser': 'System browser',
   'openWith.systemDefault': 'Open with system default',
diff --git a/desktop/src/i18n/locales/zh.ts b/desktop/src/i18n/locales/zh.ts
index f361d783..f89addbb 100644
--- a/desktop/src/i18n/locales/zh.ts
+++ b/desktop/src/i18n/locales/zh.ts
@@ -94,6 +94,7 @@ export const zh: Record<TranslationKey, string> = {
   'openProject.openFailed': '无法打开项目',
 
   // ─── Open With ─────────────────────────────────────
+  'openWith.title': '打开方式',
   'openWith.inAppBrowser': '应用内浏览器',
   'openWith.systemBrowser': '系统浏览器',
   'openWith.systemDefault': '系统默认打开',
diff --git a/desktop/src/lib/openWithContextForHref.test.ts b/desktop/src/lib/openWithContextForHref.test.ts
index 85c579c0..7b0ccd7b 100644
--- a/desktop/src/lib/openWithContextForHref.test.ts
+++ b/desktop/src/lib/openWithContextForHref.test.ts
@@ -5,7 +5,7 @@ vi.mock('./desktopRuntime', () => ({
   isLoopbackHostname: (h: string) => h === 'localhost' || h === '127.0.0.1' || h === '::1',
 }))
 
-import { openWithContextForHref } from './openWithContextForHref'
+import { openWithContextForHref, openWithContextForWorkspaceFile } from './openWithContextForHref'
 import { previewFsUrl } from './handlePreviewLink'
 
 const BASE = 'http://127.0.0.1:4321'
@@ -51,3 +51,39 @@ describe('openWithContextForHref', () => {
     expect(result).toEqual({ kind: 'file', absolutePath: '/proj/src/index.ts', relPath: 'src/index.ts', previewable: true })
   })
 })
+
+describe('openWithContextForWorkspaceFile', () => {
+  it('.md rel path → { kind:"file", absolutePath, relPath, previewable:true } with no inAppBrowserUrl', () => {
+    const result = openWithContextForWorkspaceFile('README.md', '/w/proj/README.md', { sessionId: SESSION, serverBaseUrl: BASE })
+    expect(result).toEqual({ kind: 'file', absolutePath: '/w/proj/README.md', relPath: 'README.md', previewable: true })
+  })
+
+  it('index.html rel path → also has inAppBrowserUrl equal to previewFsUrl', () => {
+    const result = openWithContextForWorkspaceFile('index.html', '/w/proj/index.html', { sessionId: SESSION, serverBaseUrl: BASE })
+    expect(result).toEqual({
+      kind: 'file',
+      absolutePath: '/w/proj/index.html',
+      relPath: 'index.html',
+      previewable: true,
+      inAppBrowserUrl: previewFsUrl(BASE, SESSION, 'index.html'),
+    })
+  })
+
+  it('.htm extension → also has inAppBrowserUrl', () => {
+    const result = openWithContextForWorkspaceFile('page.htm', '/w/proj/page.htm', { sessionId: SESSION, serverBaseUrl: BASE })
+    expect(result.kind).toBe('file')
+    if (result.kind === 'file') {
+      expect(result.inAppBrowserUrl).toBeDefined()
+      expect(result.inAppBrowserUrl).toBe(previewFsUrl(BASE, SESSION, 'page.htm'))
+    }
+  })
+
+  it('.ts rel path → no inAppBrowserUrl', () => {
+    const result = openWithContextForWorkspaceFile('src/app.ts', '/w/proj/src/app.ts', { sessionId: SESSION, serverBaseUrl: BASE })
+    expect(result.kind).toBe('file')
+    if (result.kind === 'file') {
+      expect(result.inAppBrowserUrl).toBeUndefined()
+      expect(result.previewable).toBe(true)
+    }
+  })
+})
diff --git a/desktop/src/lib/openWithContextForHref.ts b/desktop/src/lib/openWithContextForHref.ts
index b982afe6..f5431623 100644
--- a/desktop/src/lib/openWithContextForHref.ts
+++ b/desktop/src/lib/openWithContextForHref.ts
@@ -2,6 +2,23 @@ import { classifyPreviewLink } from './previewLinkRouter'
 import { previewFsUrl } from './handlePreviewLink'
 import type { OpenWithContext } from './openWithItems'
 
+const HTML_EXT = /\.(html?|xhtml)$/i
+
+/** Build an open-with context for a workspace file (we have both its relative + absolute path). */
+export function openWithContextForWorkspaceFile(
+  relPath: string,
+  absolutePath: string,
+  opts: { sessionId: string; serverBaseUrl: string },
+): OpenWithContext {
+  return {
+    kind: 'file',
+    absolutePath,
+    relPath,
+    previewable: true,
+    inAppBrowserUrl: HTML_EXT.test(relPath) ? previewFsUrl(opts.serverBaseUrl, opts.sessionId, relPath) : undefined,
+  }
+}
+
 function resolveAbsolute(workDir: string | undefined, p: string): string {
   if (!workDir || p.startsWith('/') || /^[a-zA-Z]:[\\/]/.test(p)) return p
   return `${workDir.replace(/[\\/]+$/, '')}/${p.replace(/^[/\\]+/, '')}`