fix(session-export): preserve streamed browser downloads

packages/session-query/session-export/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/session-query/session-export/README.md
-README.md: 3df11c1132715dc590d50b53588f8875015f237b
-README.zh.md: 008cf433df1104c9f7e45cd04c0e0f256e3682fb
+README.md: 4abee799c51d50342421ff594e88b03a11e785fa
+README.zh.md: 9b3ab129c132f797bbede8d8676bc8af954c1f90

packages/session-query/session-export/README.md

@@ -11,7 +11,7 @@ Web Session-log download control over the host-streamed ZIP endpoint owned by `d
 | `/export` | Record a human-command lifecycle; the submitting browser receives the local execution acknowledgment and downloads `GET /api/session.export?sessionId=<id>&includeDescendants=true`. |
 | `/export <path>` | Return an error. Browser downloads choose their destination through the browser's ordinary download behavior. |
 
-The command is mounted only by the Web bundle. The local `command/executed` acknowledgment triggers the slash download only after a successful `/export` result in the browser that submitted it; other tabs still render the durable command row without repeating the browser side effect. The Header button calls the same controller directly, so both entry paths share in-flight collapsing, cancellation on plugin disposal, HTTP error handling, browser save behavior, and the same Modal.
+The command is mounted only by the Web bundle. The local `command/executed` acknowledgment triggers the slash download only after a successful `/export` result in the browser that submitted it; other tabs still render the durable command row without repeating the browser side effect. The Header button calls the same controller directly. Both entry paths issue a `HEAD` preflight, then hand the GET URL to the browser download manager without buffering the ZIP in JavaScript; they share in-flight collapsing, cancellation of the preflight on plugin disposal, preparation-error handling, browser save behavior, and the same Modal.
 
 The Host download endpoint flushes a live root Session before `readRaw`, so a slash-triggered ZIP includes the `command/run` and `command/done` pair whose acknowledgment started the download. Cold persisted Sessions require no flush.
 
@@ -46,3 +46,4 @@ None. The log-only command lifecycle and browser download do not change the deri
 
 - The download endpoint requires a persistence backend with a per-Session raw artifact. The shipped JSONL backend supports plaintext and zstd artifacts; SQLite export is not included in this change.
 - This is a browser download, not a Host-path writer. The browser chooses the local destination; no Host path or native folder action is returned.
+- The preflight reports failures found before ZIP streaming starts. A descendant or attachment failure after the browser accepts the GET is reported by the browser download manager, not by the modal.

packages/session-query/session-export/README.zh.md

@@ -11,7 +11,7 @@ Web Session 日志下载控制，使用 `dsh-host-apiproxy` 拥有的 Host 流
 | `/export` | 记录一组用户命令生命周期；提交命令的浏览器收到本地执行确认后，下载 `GET /api/session.export?sessionId=<id>&includeDescendants=true`。 |
 | `/export <path>` | 返回错误。浏览器下载通过浏览器的普通下载行为选择目标位置。 |
 
-该命令只由 Web bundle 挂载。只有 `/export` 返回成功时，本地 `command/executed` 确认才会在提交命令的浏览器中触发斜杠下载；其他标签页仍会渲染持久命令行，但不会重复执行浏览器副作用。Header 按钮直接调用同一个控制器，因此两种入口共用并发折叠、插件释放时取消、HTTP 错误处理、浏览器保存行为和同一个 Modal。
+该命令只由 Web bundle 挂载。只有 `/export` 返回成功时，本地 `command/executed` 确认才会在提交命令的浏览器中触发斜杠下载；其他标签页仍会渲染持久命令行，但不会重复执行浏览器副作用。Header 按钮直接调用同一个控制器。两种入口都会先发出 `HEAD` 预检，再把 GET URL 交给浏览器下载管理器，JavaScript 不会缓冲 ZIP；它们共用并发折叠、插件释放时取消预检、准备阶段错误处理、浏览器保存行为和同一个 Modal。
 
 Host 下载端点会在 `readRaw` 前 flush 活动的根 Session，因此斜杠命令触发的 ZIP 会包含启动下载的 `command/run` 与 `command/done` 事件对。冷持久化 Session 不需要 flush。
 
@@ -46,3 +46,4 @@ Web bundle 将本包与 `dsh-host-apiproxy`、`dsh-commands`、`dsh-client-ui-co
 
 - 下载端点要求持久化后端具有逐 Session 原始工件。随附 JSONL 后端支持明文和 zstd 工件；本次改动不包含 SQLite 导出。
 - 这是浏览器下载，不是 Host 路径写入。目标位置由浏览器选择，不会返回 Host 路径或原生文件夹操作。
+- 预检只报告 ZIP 开始流式传输前发现的失败。浏览器接受 GET 后发生的子 Session 或附件读取失败由浏览器下载管理器报告，不通过弹窗报告。

packages/session-query/session-export/src/client/Dialog.tsx

@@ -12,7 +12,7 @@ export interface SessionExportDialogInjected {
 }
 
 export type SessionExportDialogProps =
-  PropsRuntime<'conversation.session.header.actions'>
+  PropsRuntime<'conversation.session.header.utilities'>
   & PropsLocale<typeof NS>
   & InjectFace<SessionExportDialogInjected>
 

packages/session-query/session-export/src/client/HeaderAction.module.css

@@ -1,4 +1,3 @@
-/* The 111 px design width is a floor so translated labels do not clip. */
 .sessionLogButton {
   display: inline-flex;
   align-items: center;

packages/session-query/session-export/src/client/controller.ts

@@ -18,7 +18,7 @@ export interface SessionExportDownloadState {
 }
 
 type Fetch = (input: string | URL, init?: RequestInit) => Promise<Response>
-type Save = (blob: Blob, filename: string) => void
+type Save = (url: string, filename: string) => void
 
 const INITIAL: SessionExportDownloadState = { bySession: {} }
 
@@ -32,17 +32,15 @@ export function sessionLogZipFilename(sessionId: SessionId): string {
 }
 
 /**
- * Trigger a browser save without copying the response blob.
- * @param blob - complete ZIP response body.
+ * Hand a Host download URL to the browser download manager.
+ * @param url - same-origin Host download URL.
  * @param filename - browser download filename.
  */
-export function downloadBlob(blob: Blob, filename: string): void {
-  const url = URL.createObjectURL(blob)
+export function downloadUrl(url: string, filename: string): void {
   const anchor = document.createElement('a')
   anchor.href = url
   anchor.download = filename
   anchor.click()
-  setTimeout(() => { URL.revokeObjectURL(url) }, 0)
 }
 
 /** Resolve the browser's Host base with the connection carrier's null-origin fallback. */
@@ -69,7 +67,7 @@ export class SessionExportDownloadController {
    */
   constructor(
     private readonly fetcher: Fetch = (input, init) => fetch(input, init),
-    private readonly save: Save = downloadBlob,
+    private readonly save: Save = downloadUrl,
   ) {}
 
   /**
@@ -89,15 +87,6 @@ export class SessionExportDownloadController {
     return done
   }
 
-  /**
-   * Present a command failure without issuing an HTTP request.
-   * @param sessionId - Session whose modal reports the failure.
-   * @param error - stable command failure text.
-   */
-  fail(sessionId: SessionId, error: string): void {
-    this.publish(sessionId, { open: true, status: 'error', error })
-  }
-
   /**
    * Close one Session's dialog without cancelling an in-flight browser download.
    * @param sessionId - Session whose modal closes.
@@ -125,12 +114,12 @@ export class SessionExportDownloadController {
       const url = new URL('/api/session.export', hostBase())
       url.searchParams.set('sessionId', sessionId)
       url.searchParams.set('includeDescendants', 'true')
-      const response = await this.fetcher(url, { signal })
+      const response = await this.fetcher(url, { method: 'HEAD', signal })
       if (!response.ok) {
         const detail = await response.text().catch(() => '')
         throw new Error(`Export failed: HTTP ${response.status}${detail === '' ? '' : ` ${detail}`}`)
       }
-      this.save(await response.blob(), sessionLogZipFilename(sessionId))
+      this.save(url.toString(), sessionLogZipFilename(sessionId))
       const open = this.store.getSnapshot().bySession[String(sessionId)]?.open ?? true
       this.publish(sessionId, { open, status: 'success', error: null })
     } catch (error: unknown) {

packages/session-query/session-export/tests/client-apply.client.spec.tsx

@@ -43,12 +43,10 @@ describe('session-export browser plugin', () => {
     expect(entry?.component).toBe(SessionExportHeader)
     expect(entry?.options).toMatchObject({ id: 'session-export' })
     const injected = (entry?.inject as unknown as () => import('../src/client/Dialog.tsx').SessionExportDialogInjected)()
-    b.ctx.sessionExport.fail(SID, 'failed')
+    await injected.request(SID)
     expect(b.ctx.sessionExport.store.getSnapshot().bySession[SID]?.status).toBe('error')
     injected.dismiss(SID)
     expect(b.ctx.sessionExport.store.getSnapshot().bySession[SID]?.open).toBe(false)
-    await injected.request(SID)
-    expect(b.ctx.sessionExport.store.getSnapshot().bySession[SID]?.status).toBe('error')
 
     await b.fiber.dispose()
     expect(b.slots.entries('conversation.session.header.utilities')).toHaveLength(0)

packages/session-query/session-export/tests/controller.client.spec.ts

@@ -2,7 +2,7 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import type { SessionId } from '@deepseek-ai/dsh-client-runtime/client'
 import {
-  downloadBlob, SessionExportDownloadController, sessionLogZipFilename,
+  downloadUrl, SessionExportDownloadController, sessionLogZipFilename,
 } from '../src/client/controller.ts'
 
 const SID = 'session-export-controller' as SessionId
@@ -25,9 +25,12 @@ describe('SessionExportDownloadController', () => {
     expect(url.pathname).toBe('/api/session.export')
     expect(url.searchParams.get('sessionId')).toBe(SID)
     expect(url.searchParams.get('includeDescendants')).toBe('true')
+    expect(init.method).toBe('HEAD')
     expect(init.signal).toBeInstanceOf(AbortSignal)
-    expect(save).toHaveBeenCalledWith(expect.any(Object), 'dsh-session-session-export-controller.zip')
-    expect((save.mock.calls[0]?.[0] as Blob).size).toBe(3)
+    expect(save).toHaveBeenCalledWith(
+      url.toString(),
+      'dsh-session-session-export-controller.zip',
+    )
     expect(controller.store.getSnapshot().bySession[SID]).toEqual({
       open: true, status: 'success', error: null,
     })
@@ -50,7 +53,7 @@ describe('SessionExportDownloadController', () => {
     controller.dismiss(SID)
   })
 
-  it('publishes HTTP, transport, and command failures without leaking rejections', async () => {
+  it('publishes HTTP and transport failures without leaking rejections', async () => {
     const http = new SessionExportDownloadController(
       async () => new Response('backend unavailable', { status: 500 }), vi.fn(),
     )
@@ -65,8 +68,6 @@ describe('SessionExportDownloadController', () => {
     await transport.download(SID)
     expect(transport.store.getSnapshot().bySession[SID]?.error).toBe('offline')
 
-    transport.fail(SID, 'command failed')
-    expect(transport.store.getSnapshot().bySession[SID]?.error).toBe('command failed')
     transport.dismiss('absent' as SessionId)
 
     const emptyDetail = new SessionExportDownloadController(
@@ -102,14 +103,14 @@ describe('SessionExportDownloadController', () => {
     vi.stubGlobal('location', { origin: 'null' })
     const fetcher = vi.fn(async (_input: string | URL, _init?: RequestInit) => new Response('zip'))
     vi.stubGlobal('fetch', fetcher)
-    vi.spyOn(URL, 'createObjectURL').mockReturnValue('blob:default')
-    vi.spyOn(URL, 'revokeObjectURL').mockImplementation(() => {})
-    vi.spyOn(HTMLAnchorElement.prototype, 'click').mockImplementation(() => {})
+    const click = vi.spyOn(HTMLAnchorElement.prototype, 'click').mockImplementation(() => {})
     const controller = new SessionExportDownloadController()
 
     await controller.download(SID)
 
     expect((fetcher.mock.calls[0]?.[0] as URL).origin).toBe('http://dsh.internal')
+    expect(fetcher.mock.calls[0]?.[1]).toMatchObject({ method: 'HEAD' })
+    expect(click).toHaveBeenCalledOnce()
   })
 
   it('defaults dialog openness when state is externally cleared before settlement', async () => {
@@ -132,19 +133,14 @@ describe('SessionExportDownloadController', () => {
 })
 
 describe('browser download helpers', () => {
-  it('sanitizes the archive filename and revokes the object URL after the click', () => {
-    vi.useFakeTimers()
-    const create = vi.spyOn(URL, 'createObjectURL').mockReturnValue('blob:session')
-    const revoke = vi.spyOn(URL, 'revokeObjectURL').mockImplementation(() => {})
+  it('sanitizes the archive filename and hands the URL to a download anchor', () => {
     const click = vi.spyOn(HTMLAnchorElement.prototype, 'click').mockImplementation(() => {})
 
     expect(sessionLogZipFilename('a/b' as SessionId)).toBe('dsh-session-a_b.zip')
-    downloadBlob(new Blob(['zip']), 'archive.zip')
-    expect(create).toHaveBeenCalledOnce()
+    downloadUrl('http://host/api/session.export?sessionId=a', 'archive.zip')
     expect(click).toHaveBeenCalledOnce()
-    expect(revoke).not.toHaveBeenCalled()
-    vi.runAllTimers()
-    expect(revoke).toHaveBeenCalledWith('blob:session')
-    vi.useRealTimers()
+    const anchor = click.mock.instances[0] as HTMLAnchorElement
+    expect(anchor.href).toBe('http://host/api/session.export?sessionId=a')
+    expect(anchor.download).toBe('archive.zip')
   })
 })

packages/session-query/session-export/tests/dialog.client.spec.tsx

@@ -33,7 +33,11 @@ afterEach(cleanup)
 describe('SessionExportDialog', () => {
   it('shows a controller failure and closes it without reading Session history', async () => {
     const b = bench()
-    act(() => { b.controller.fail(SID, 'toolbar failed') })
+    act(() => {
+      b.controller.store.set({
+        bySession: { [SID]: { open: true, status: 'error', error: 'toolbar failed' } },
+      })
+    })
     const dialog = await b.view.findByRole('dialog', { name: 'Session export failed' })
     expect(dialog.textContent).toContain('toolbar failed')
     const close = b.view.getAllByRole('button', { name: 'Close' })[0]
@@ -57,7 +61,11 @@ describe('SessionExportDialog', () => {
 
   it('uses fallback copy when a failure has no detail', async () => {
     const b = bench()
-    act(() => { b.controller.fail(SID, '') })
+    act(() => {
+      b.controller.store.set({
+        bySession: { [SID]: { open: true, status: 'error', error: '' } },
+      })
+    })
     const dialog = await b.view.findByRole('dialog', { name: 'Session export failed' })
     expect(dialog.textContent).toContain('Could not start the Session export.')
     const close = b.view.getAllByRole('button', { name: 'Close' }).at(-1)

packages/session-query/session-export/tests/loader-composition.client.spec.ts

@@ -54,7 +54,8 @@ describe('session-export real Loader composition', () => {
     })
     await context.loader.await()
 
-    const session = context.sessions.create(SessionId('loader-session-export'), { meta: { createdAt: 1 } })
+    const session = (context.get('sessions') as unknown as SessionStore)
+      .create(SessionId('loader-session-export'), { meta: { createdAt: 1 } })
     const agent = { session, status: 'idle', options: {} } as unknown as Agent
     expect(context.commands.list(agent)).toContainEqual({
       name: 'export', description: 'Download this Session log as a ZIP archive',

packages/session-query/session-export/tsconfig.client.json

@@ -1,22 +0,0 @@
-{
-  "extends": "../../../tsconfig.base.client.json",
-  "compilerOptions": {
-    "rootDir": "src",
-    "outDir": "lib/types",
-    "tsBuildInfoFile": "lib/tsconfig.client.tsbuildinfo"
-  },
-  "include": [
-    "src/client",
-    "src/css-modules.d.ts"
-  ],
-  "references": [
-    { "path": "../../../vendor/cordis" },
-    { "path": "../../interaction/commands" },
-    { "path": "../../client/locale" },
-    { "path": "../../client/runtime" },
-    { "path": "../../client/ui-command" },
-    { "path": "../../client/ui-conversation" },
-    { "path": "../../client/ui-primitives" },
-    { "path": "../../client/ui-slots" }
-  ]
-}

packages/session-query/session-export/tsconfig.host.json

@@ -1,17 +0,0 @@
-{
-  "extends": "../../../tsconfig.base.json",
-  "compilerOptions": {
-    "rootDir": "src",
-    "outDir": "lib/types",
-    "tsBuildInfoFile": "lib/tsconfig.host.tsbuildinfo"
-  },
-  "files": [
-    "src/index.ts",
-    "src/invariant.ts"
-  ],
-  "references": [
-    { "path": "../../../vendor/cordis" },
-    { "path": "../../interaction/commands" },
-    { "path": "../../support/invariants" }
-  ]
-}

packages/session-query/session-export/tsconfig.json

@@ -1,7 +1,21 @@
 {
-  "files": [],
+  "extends": "../../../tsconfig.base.client.json",
+  "compilerOptions": {
+    "rootDir": "src",
+    "outDir": "lib/types"
+  },
+  "include": [
+    "src"
+  ],
   "references": [
-    { "path": "./tsconfig.host.json" },
-    { "path": "./tsconfig.client.json" }
+    { "path": "../../../vendor/cordis" },
+    { "path": "../../interaction/commands" },
+    { "path": "../../client/locale" },
+    { "path": "../../client/runtime" },
+    { "path": "../../client/ui-command" },
+    { "path": "../../client/ui-conversation" },
+    { "path": "../../client/ui-primitives" },
+    { "path": "../../client/ui-slots" },
+    { "path": "../../support/invariants" }
   ]
 }