feat(web): export the session log from the trajectory toolbar

The 导出 button fetches GET /api/session.export and saves the ZIP (root
artifact plus subagent descendants). The plugin exposes exportLog through
the view's inject face, resolves the tab label through the locale service,
and disables the button while in flight; fixture mode answers 404 so the
error bar explains the gap.

packages/client/ui-trajectory/tests/views.spec.tsx

@@ -27,6 +27,7 @@ import {
 } from '@deepseek-ai/dsh-client-ui-conversation/src/client/skeleton/ConversationSession.tsx'
 import { createChatStore } from '@deepseek-ai/dsh-client-ui-conversation/src/client/stores.ts'
 import { zh as conversationZh } from '@deepseek-ai/dsh-client-ui-conversation/src/client/locales.ts'
+import { apply as localeApply, inject as localeInject } from '@deepseek-ai/dsh-client-locale/client'
 import { apply, inject } from '@deepseek-ai/dsh-client-ui-trajectory/client'
 import { apply as nodeApply } from '@deepseek-ai/dsh-client-ui-trajectory'
 import type { TrajectoryTurnModel } from '../src/client/layout.ts'
@@ -111,6 +112,12 @@ function standaloneDuration(): Pick<
   }
 }
 
+function standaloneExport(
+  onExport: () => Promise<void> = vi.fn(() => Promise.resolve()),
+): Pick<ComponentProps<typeof TrajectoryView>, 'exportLog'> {
+  return { exportLog: onExport }
+}
+
 function fakeSession(nodes: ConversationSnapshot['nodes']) {
   const store = createSnapshotStore({
     nodes, pending: [], partial: null,
@@ -168,6 +175,8 @@ async function bench(snapshot = historySnapshot(NODES)) {
   slots.register(
     { name: 'conversation.view', id: 'chat', order: 0, label: 'Chat' } as never, chatBody as never)
   ctx.provide('sessionHistory', { source: () => history })
+  // The locale plugin backs the locale-aware view tab label ('locale' in inject).
+  ctx.plugin({ inject: [...localeInject], apply: localeApply })
   const fiber = ctx.plugin({ inject: [...inject], apply })
   await fiber.await()
   return { ctx, slots, fiber, loadHistoryTail, loadOlderHistory }
@@ -218,6 +227,7 @@ function mount(slots: SlotsService, nodes: ConversationSnapshot['nodes'] = NODES
           loadHistoryTail: trajectory.loadHistoryTail,
           loadOlderHistory: trajectory.loadOlderHistory,
           setActualDuration: trajectory.setActualDuration,
+          exportLog: trajectory.exportLog,
           useHistory: bindSnapshotSelector(trajectory.hooks.history),
           useDuration: bindSnapshotSelector(trajectory.hooks.duration),
         }
@@ -331,6 +341,17 @@ describe('tab switching in ConversationRoot', () => {
     expect(signal?.aborted).toBe(true)
   })
 
+  it('labels the trajectory tab in the active locale', async () => {
+    const b = await bench()
+    const labelOf = () => tabsOf(b.slots).find(tab => tab.id === 'trajectory')?.label
+    expect(labelOf()).toBe('Trajectory')
+    const locale = b.ctx.get('locale') as { setLocale(id: string): void }
+    locale.setLocale('zh')
+    expect(labelOf()).toBe('轨迹')
+    locale.setLocale('en')
+    expect(labelOf()).toBe('Trajectory')
+  })
+
   it('opens a local record inspector and switches payload tabs without opening chat details', async () => {
     const b = await bench()
     mount(b.slots)
@@ -1066,6 +1087,7 @@ describe('timeline projection', () => {
         ...standaloneProps([]),
         ...standaloneHistory(historySnapshot([])),
         ...standaloneDuration(),
+        ...standaloneExport(),
       },
     ))
     expect(screen.getByRole('toolbar', { name: 'Trajectory toolbar' })).toBeTruthy()
@@ -1073,6 +1095,55 @@ describe('timeline projection', () => {
   })
 })
 
+describe('session log export', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals()
+    Reflect.deleteProperty(URL, 'createObjectURL')
+    Reflect.deleteProperty(HTMLAnchorElement.prototype, 'click')
+  })
+
+  it('downloads the host-streamed ZIP with descendants on click', async () => {
+    // exportLog always fetches a URL instance, so the mock's shape stays narrow.
+    const fetchMock = vi.fn(async (input: URL) => {
+      expect(input.pathname).toBe('/api/session.export')
+      expect(input.searchParams.get('sessionId')).toBe(SID)
+      expect(input.searchParams.get('includeDescendants')).toBe('true')
+      return new Response('zip-bytes')
+    })
+    vi.stubGlobal('fetch', fetchMock)
+    const createObjectURL = vi.fn(() => 'blob:export')
+    URL.createObjectURL = createObjectURL
+    const clickAnchor = vi.fn()
+    HTMLAnchorElement.prototype.click = clickAnchor
+    const b = await bench(historySnapshot(NODES))
+    mount(b.slots)
+    fireEvent.click(screen.getByRole('tab', { name: 'Trajectory' }))
+    fireEvent.click(screen.getByRole('button', { name: '导出会话日志' }))
+    await vi.waitFor(() => {
+      expect(fetchMock).toHaveBeenCalledOnce()
+    })
+    // The blob download lands a few microtasks after the fetch settles.
+    // The blob download lands a few microtasks after the fetch settles.
+    await vi.waitFor(() => {
+      expect(createObjectURL).toHaveBeenCalled()
+    })
+    expect(clickAnchor).toHaveBeenCalled()
+  })
+
+  it('surfaces the download failure in the visible alert bar', async () => {
+    vi.stubGlobal('fetch', vi.fn(async () => new Response('boom', { status: 404 })))
+    const b = await bench(historySnapshot(NODES))
+    mount(b.slots)
+    fireEvent.click(screen.getByRole('tab', { name: 'Trajectory' }))
+    fireEvent.click(screen.getByRole('button', { name: '导出会话日志' }))
+    await vi.waitFor(() => {
+      const alert = screen.queryByRole('alert')
+      expect(alert).not.toBeNull()
+      expect(alert!.textContent).toContain('HTTP 404')
+    })
+  })
+})
+
 describe('TrajectoryView branches', () => {
   it('persists the duration preference through the runtime snapshot-store seam', () => {
     const firstDuration = createTrajectoryDurationStore()
@@ -1083,6 +1154,7 @@ describe('TrajectoryView branches', () => {
     const first = render(
       <TrajectoryView
         {...commonProps}
+        {...standaloneExport()}
         useDuration={bindSnapshotSelector(firstDuration)}
         setActualDuration={(value) => { firstDuration.set(value) }}
       />,
@@ -1098,6 +1170,7 @@ describe('TrajectoryView branches', () => {
     render(
       <TrajectoryView
         {...commonProps}
+        {...standaloneExport()}
         useDuration={bindSnapshotSelector(restoredDuration)}
         setActualDuration={(value) => { restoredDuration.set(value) }}
       />,
@@ -1162,6 +1235,7 @@ describe('TrajectoryView branches', () => {
       <TrajectoryView
         {...standaloneProps([])}
         {...standaloneDuration()}
+        {...standaloneExport()}
         useHistory={bindSnapshotSelector(store)}
         loadHistoryTail={vi.fn(() => Promise.resolve())}
         loadOlderHistory={vi.fn(() => Promise.resolve(false))}
@@ -1196,6 +1270,7 @@ describe('TrajectoryView branches', () => {
       <TrajectoryView
         {...standaloneProps([])}
         {...standaloneDuration()}
+        {...standaloneExport()}
         useHistory={bindSnapshotSelector(store)}
         loadHistoryTail={vi.fn(() => Promise.resolve())}
         loadOlderHistory={vi.fn(() => Promise.resolve(false))}
@@ -1225,6 +1300,7 @@ describe('TrajectoryView branches', () => {
       <TrajectoryView
         {...standaloneProps([])}
         {...standaloneDuration()}
+        {...standaloneExport()}
         useHistory={bindSnapshotSelector(store)}
         loadHistoryTail={vi.fn(() => Promise.resolve())}
         loadOlderHistory={vi.fn(() => Promise.resolve(false))}
@@ -1274,6 +1350,7 @@ describe('TrajectoryView branches', () => {
       <TrajectoryView
         {...standaloneProps([])}
         {...standaloneDuration()}
+        {...standaloneExport()}
         useHistory={bindSnapshotSelector(store)}
         loadHistoryTail={vi.fn(() => Promise.resolve())}
         loadOlderHistory={vi.fn(() => Promise.resolve(false))}