Merge pull request #619 from omdsh-dev/fix/auto-activation-native-landing

fix(shell): land auto-activation in DSH's native right Sidebar

docs/plans/2026-09-09-dsh-0.1.5-alpha.2-adaptation.md

@@ -18,6 +18,8 @@ DSH `dsh-v0.1.5-alpha.1..dsh-v0.1.5-alpha.2` 的宿主契约里有一批会实
 | 6 | 基线升到 0.1.5-alpha.2（peer 下限 / manifest / CI 钉版） | 插件基线 = alpha.2 only；alpha.1 用户留在 v0.19.0-alpha.0 |
 
 > 后续（2026-09-10）：`SidebarRightGuideEntry.description` 在 DSH 0.1.5-rc.1 回归（可选，且宿主只在 guide 列出的条目 ≤ 4 条时渲染），插件已在 **v0.19.0** 恢复该字段——见 [2026-09-10-dsh-0.1.5-rc.1-adaptation.md](./2026-09-10-dsh-0.1.5-rc.1-adaptation.md)。
+>
+> 后续（2026-09-10）：退役自绘右侧面板（#605）时，`use-host-feeds.ts` 的三处自动激活被误改成 `target: 'bottom'`，任务页因此落到插件自己的底部工作台而非 DSH 原生右侧栏。修复见 [2026-09-10-auto-activation-native-landing-fix.md](./2026-09-10-auto-activation-native-landing-fix.md)。
 
 ## 决策
 

docs/plans/2026-09-10-auto-activation-native-landing-fix.md

@@ -0,0 +1,60 @@
+# 自动激活落点修复：任务页回到 DSH 原生右侧栏
+
+日期：2026-09-10　分支：`fix/auto-activation-native-landing`
+
+## 背景
+
+用户报告：**自动打开的侧边栏是底栏，而不是右侧边栏**。两个自动激活开关（`autoOpenSubagent` / `autoOpenJobs`）与子代理拓扑跳回在 v0.19.0 上把任务页（`subagent` tab）开进了插件自绘的**底部工作台**，底栏随之展开；而产品文案描述的是侧边栏落点——README 特性表「新子代理 / 新任务可自动激活任务页，**宽屏同时展开侧边栏**，窄屏不强制展开全屏抽屉」，`settingsSubagentDesc` / `settingsJobsDesc` 及全部 20 份词典同样措辞，README 的 #314 条目也写着「宽屏展开侧边栏，窄屏只准备 Tab」。
+
+## 根因
+
+`223b254`（v0.19.0-alpha.0「退役插件自绘右侧面板与自由窗口」）改写了 `src/client/sidebar/use-host-feeds.ts` 的三处触发：
+
+| | 改动前（v0.18.x） | 改动后（v0.19.0） |
+|---|---|---|
+| 展开 | `store.reduce(s => s.panelOpen ? s : togglePanel(s))`（宽屏才展开） | 无（由落点决定） |
+| 落点 | `activePane = firstLeaf(s.splits).id` + `openTab({ type:'subagent', title })` —— **无 `target`** | `openTab({ type:'subagent', title, target:'bottom' })` |
+
+`service.ts:683` 的判据是「装了原生面 + 非 `bottom` → 落 DSH 原生右侧栏」，`target: 'bottom'` 直接绕过它走 `land = openTabInBottomPane`（`service.ts:744` → `state.ts:453`，置 `bottomOpen: true`）。也就是说：退役右侧面板时，`splits`（插件自己的右面板）消失，落点被改成了插件自己的**底**面板，而正解是当时同文件其它打开早已默认落上的新宿主——DSH 原生右侧栏。
+
+## 决策
+
+| # | 决策 | 理由 |
+|---|---|---|
+| 1 | 三处触发改回默认落点（`'right'`） | 宿主 `openContent` 内部 `planSetExpanded(state, true)`（`dsh-client-ui-sidebar-right`），打开即在同一步展开原生栏；这才是文案里的「侧边栏」 |
+| 2 | 后台活动（子代理 / 新任务）在窄屏**停放**，不展开 | 宿主 `RightbarSeat` 有 `autoFullscreen = viewportWidth < 768`，该宽度下原生栏以 `position: fixed; inset: 0` 全屏绘制——展开即整屏抢占，正是 #373 修掉的行为。宿主没有「只放 tab、不展开」的公开选项，故开前读 `ctx.sidebarRight.isExpanded()`、开后 `toggleExpanded()` 收回；两次提交落在同一 React 批内，中间态不会渲染 |
+| 3 | 停放仅在目标会话在屏时执行 | `isExpanded` / `toggleExpanded` 作用于**已挂载会话**（`mounted()` = `binding.surfaces[binding.sessionId]`）；目标不在屏时执行会误动用户当前那一栏 |
+| 4 | 拓扑跳回（用户点击）一律展开 | 它是显式手势，不是后台活动；对齐 v0.18.x 跳回无窄屏门禁的语义 |
+| 5 | 底部工作台自有流程保持 `target: 'bottom'` | 底栏 `+` 菜单（`Sidebar.tsx:628`）与首次展开自动终端（`:336`）本就该落底栏；`OpenTabSeed.target` API 不变 |
+
+阈值一致性：插件既有 `NARROW_MAX_WIDTH = 768`（`width < 768`，`src/client/breakpoints.ts`）与宿主 `viewportWidth < 768` 的全屏规则逐字对齐，不引入第二个断点。
+
+窄屏语义与 v0.18.x 等价：**tab 已就位、抽屉不展开**（用户点开会话头右侧的展开控件即可看到任务页）。
+
+## 改动清单（子系统级）
+
+| 子系统 | 文件 | 变更 |
+|---|---|---|
+| 触发 | `src/client/sidebar/use-host-feeds.ts` | 新增模块内 `activateTasksPage(ctx, sessionId, { background })`（落点 + 停放判定集中在此）；三处调用改为它（子代理 / 后台任务 `background: true`，跳回 `false`）；重新引入 `isNarrowWidth`；三段 docblock 与文件头同步 |
+| 测试 | `tests/sidebar-auto-activation.spec.tsx` | 断言原生面收到 `openTab { kind:'subagent', revealIfOpened:true }`、底部工作台保持原状（未展开、未新增 tab）、窄屏停放次数（1 / 0）、宽屏与已展开栏不停放、去抖触发时读视口、跳回不停放 |
+
+无 API / 持久化 / i18n / README 行为文案改动：文案本就在描述修复后的行为。
+
+## 验证
+
+- **回归守护（确定性）**：新 spec 10 passed；把 `src/client/sidebar/use-host-feeds.ts` 回退到 `HEAD` 后同 10 条**全红**（10 failed），证明它测的正是这次修复。
+- **门槛**：`pnpm typecheck` / `pnpm lint` / `pnpm check:consumer-types` 干净；`pnpm test` = **124 files / 1299 passed / 9 skipped**（较基线 +3 条，即本 spec 的净增）。
+- **打包挂载**：`pnpm build && pnpm pack && pnpm test:mount` = **7 passed**（真实 DSH 0.1.5-rc.1，scratch profile，不触碰用户 `~/.dsh`）。
+- **环境事实（踩过一次）**：本机 PATH 上的 `dsh` 是 **0.1.2-rc.1**，用它跑挂载车道会在 `dsh plugin add` 后报 `dsh-better-sidebar 未出现在 dsh.profile.bundles 中——挂载未注册`（该版本不会把 `file:` tarball 注册进 profile bundles，且插件 peer 要求 `^0.1.5-rc.1`）。CI 装的是钉版 0.1.5-rc.1；本地需用同版本的 shim / `DSH_CMD` 才能复现车道结果。
+- **真机**：见 PR 描述（3080 实例，web profile 换装新 tarball 后人工触发子代理 / 后台任务确认）。
+
+## 未覆盖（诚实记录）
+
+- 挂载车道是 keyless 的（无模型），无法真派生子代理或后台任务，因此**该行为只有单测是确定性证据**；宿主 `session/create` 的请求体不接受 `origin` / `parentId`，也无法用 RPC 造出 `origin: 'subagent'` 的子会话，所以真机断言只能依赖人工触发或非确定性的 prompt。
+- 宿主若在窄屏自行折叠（`shown && !fullscreen && !canShow` 的 room rule），停放不会与之冲突（两者都指向「不展开」）。
+
+## 不做
+
+- 不新增设置项、不改变 `OpenTabSeed.target` 的语义、不把任务页改到别处承载。
+- 不动底栏 `+` 菜单 / 首次展开自动终端（它们是底部工作台自己的流程）。
+- 不改 DSH 源码（仓库硬约束 §1）。

src/client/sidebar/use-host-feeds.ts

@@ -8,6 +8,7 @@
 import { useEffect, useRef } from 'react'
 import type { Context, SidebarSessionList } from '../../context-types.ts'
 import { reconcileAgentTerminals, type SidebarStore } from '../state.ts'
+import { isNarrowWidth } from '../breakpoints.ts'
 import { detectNewDirectSubagent } from '../subagent-detect.ts'
 import { detectNewJob } from '../subagent-jobs.ts'
 import { t } from '../locales.ts'
@@ -26,6 +27,55 @@ const FAILURE_LIMIT = 3
  */
 const AUTO_OPEN_DEBOUNCE_MS = 500
 
+/**
+ * The native column's public face, as this module reaches it. Both actions
+ * act on the session whose surface is MOUNTED (the controller reads its
+ * binding), which is why the park below is gated on the target session being
+ * the on-screen one.
+ */
+interface NativeColumnFace {
+  isExpanded?: () => boolean
+  toggleExpanded?: () => void
+}
+
+/**
+ * Activate the Tasks page (the `subagent` tab type) in DSH's native right
+ * Sidebar — the landing the two auto-open switches promise: the right column
+ * IS the sidebar the user means, while the plugin's own bottom workbench only
+ * serves its own flows (its `+` menu and the first-expansion terminal). Every
+ * other open in this plugin already lands there, so a `target: 'bottom'` here
+ * puts the Tasks page in the bottom bar instead.
+ *
+ * A background activation must not take over a narrow viewport: below 768px
+ * the host draws that column FULLSCREEN, so the tab is placed and the column
+ * is put back to collapsed — parked, waiting behind the expand control,
+ * instead of covering the chat. The host expands on every open
+ * (`openContent` plans `setExpanded(true)`) and offers no option to suppress
+ * it, hence the read-then-restore pair: both commits land in one React batch,
+ * so the column never renders the intermediate state. The viewport is read
+ * when the activation FIRES (the debounced subagent trigger included), so a
+ * resize while arming is honoured.
+ *
+ * @param ctx - the client context (`ctx.sidebarRight` + `ctx.betterSidebar`).
+ * @param sessionId - the session the feed reports the activity for.
+ * @param options.background - `true` for background activity (parks on narrow
+ *   viewports); `false` for the explicit topology jump-back, which is a user
+ *   gesture and always leaves the column as the host expanded it.
+ */
+function activateTasksPage(ctx: Context, sessionId: string, options: { background: boolean }): void {
+  const column = ctx.get('sidebarRight') as unknown as NativeColumnFace | undefined
+  const park = options.background
+    // The face acts on the MOUNTED session: parking is only meaningful (and
+    // only safe) when the activation targets the one on screen.
+    && ctx.sessions.list.getSnapshot().current === sessionId
+    && isNarrowWidth(window.innerWidth)
+    // Only a column the user had COLLAPSED is put back: an expanded one is in
+    // use, and closing it under the user would be worse than the takeover.
+    && column?.isExpanded?.() === false
+  ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
+  if (park) column?.toggleExpanded?.()
+}
+
 export function useHostFeeds(feeds: {
   ctx: Context
   store: SidebarStore
@@ -166,11 +216,11 @@ export function useHostFeeds(feeds: {
    * Subagent auto-activation: the moment the current conversation spawns its
    * FIRST direct subagent (a 0 → N transition on the list feed), the "auto
    * open" pref is on, and the Tasks tab type is enabled in settings, activate
-   * the Tasks page. Single-instance semantics focus an existing pane tab in
+   * the Tasks page in DSH's native right Sidebar. Single-instance semantics
-   * place or raise an existing free window; a new tab lands in the right pane
+   * focus an existing tab in place; a new tab lands in that column and is
-   * and is never duplicated. On wide viewports the right panel also expands;
+   * never duplicated. Landing it EXPANDS the column on wide viewports, while
-   * on narrow viewports background activity never forces the full-screen
+   * a narrow viewport (where the host draws that column fullscreen) parks the
-   * drawer open over the chat.
+   * tab instead of taking the screen over — see {@link activateTasksPage}.
    * Switching to a session that already has subagents never triggers — its
    * baseline starts at the current count — so a deliberate layout is never
    * fought.
@@ -196,7 +246,7 @@ export function useHostFeeds(feeds: {
       if (!detectNewDirectSubagent(baseline, ctx.sessions.list.getSnapshot(), sessionId)) return
       if (!store.getPrefs().autoOpenSubagent) return
       if (ctx.get('betterSidebar')?.isTabEnabled('subagent') === false) return
-      ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent'), target: 'bottom' })
+      activateTasksPage(ctx, sessionId, { background: true })
     }, AUTO_OPEN_DEBOUNCE_MS)
     autoOpenPendingRef.current = { baseline, timer }
   }, [sessionList, sessionId, store, ctx])
@@ -212,11 +262,12 @@ export function useHostFeeds(feeds: {
    * Job auto-activation: the moment a NEW background job appears for the
    * current conversation (a job id the previous snapshot lacked), the
    * auto-open pref is on, and the Tasks tab type is enabled, activate the Tasks
-   * page that contains the background-jobs section. The right panel expands
+   * page that contains the background-jobs section — in DSH's native right
-   * only on wide viewports. Unlike the subagent trigger (0 → N only), ANY
+   * Sidebar, expanded on wide viewports and parked on narrow ones exactly like
-   * new job id triggers: the agent may start several jobs in one session, and
+   * the subagent trigger ({@link activateTasksPage}). Unlike that trigger
-   * each should surface. A fresh page load never triggers — its baseline starts
+   * (0 → N only), ANY new job id triggers: the agent may start several jobs in
-   * at the current snapshot.
+   * one session, and each should surface. A fresh page load never triggers —
+   * its baseline starts at the current snapshot.
    */
   const jobBaselineRef = useRef<SidebarSessionList | undefined>(undefined)
   useEffect(() => {
@@ -226,7 +277,7 @@ export function useHostFeeds(feeds: {
     if (!detectNewJob(prev, sessionList, sessionId)) return
     if (!store.getPrefs().autoOpenJobs) return
     if (ctx.get('betterSidebar')?.isTabEnabled('subagent') === false) return
-    ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent'), target: 'bottom' })
+    activateTasksPage(ctx, sessionId, { background: true })
   }, [sessionList, sessionId, store, ctx])
 
   /**
@@ -235,17 +286,18 @@ export function useHostFeeds(feeds: {
    * session's OWN layout (a fresh child session defaults to the explorer).
    * The README contract says the Subagent page must stay open with the jumped
    * node highlighted — so once the current session becomes the recorded jump
-   * target, re-open the Subagent page on top of the child's layout (expanding
+   * target, re-open the Tasks page on top of the child's layout, in DSH's
-   * the panel first if it is collapsed). Only this explicit node click arms
+   * native right Sidebar. This one is an explicit user gesture, so it always
-   * the flag, so switching to a subagent session by any other means keeps
+   * takes the host's expansion (no narrow-viewport parking). Only this node
-   * that session's own layout untouched.
+   * click arms the flag, so switching to a subagent session by any other means
+   * keeps that session's own layout untouched.
    */
   const subagentJumpRef = useRef<string | undefined>(undefined)
   useEffect(() => {
     const pending = subagentJumpRef.current
     if (pending === undefined || sessionId !== pending) return
     subagentJumpRef.current = undefined
-    ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent'), target: 'bottom' })
+    activateTasksPage(ctx, sessionId, { background: false })
   }, [sessionId, store, ctx])
 
   return { subagentJumpRef }

tests/sidebar-auto-activation.spec.tsx

@@ -1,13 +1,21 @@
 /**
- * Real-Sidebar regressions for issue #162: background activity (a new
+ * Auto-activation regressions for issue #162: background activity (a new
- * subagent, a new background job) activates the Tasks page in the bottom
+ * subagent, a new background job) activates the Tasks page in DSH's NATIVE
- * workbench. The right column belongs to DSH's native Sidebar, so there is no
+ * right Sidebar — the column the two auto-open switches and the README promise
- * full-screen drawer to guard against any more — the activation lands in the
+ * ("wide viewports also expand the sidebar, while narrow full-screen drawers
- * docked workbench on every viewport width.
+ * are not forced open"). The plugin's own bottom workbench is NOT that
+ * surface: it serves only its own flows (its + menu, the first-expansion
+ * auto-terminal), so a background activation must leave it exactly as it was.
+ *
+ * The narrow half of that promise is a PARK: the host draws the native column
+ * fullscreen below 768px and expands it on every open, so the activation places
+ * the tab and puts the column back to collapsed (src/client/sidebar/
+ * use-host-feeds.ts `activateTasksPage`). The topology jump-back is an explicit
+ * user gesture and always takes the host's expansion.
  */
 // @vitest-environment jsdom
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import { createElement } from 'react'
+import { createElement, useEffect, useRef, type ReactNode } from 'react'
 import { createRoot, type Root } from 'react-dom/client'
 import { act } from 'react-dom/test-utils'
 
@@ -15,8 +23,13 @@ import { setupReactAct } from './test-utils.ts'
 setupReactAct()
 
 import { Sidebar } from '../src/client/Sidebar.tsx'
-import { allLeaves, createSidebarStore, firstLeaf, type SidebarStore } from '../src/client/state.ts'
+import { allLeaves, createSidebarStore, type SidebarStore } from '../src/client/state.ts'
-import { createBetterSidebarService, type BetterSidebarService } from '../src/client/service.ts'
+import {
+  createBetterSidebarService,
+  type BetterSidebarService,
+  type SidebarSurface,
+  type TabComponentProps,
+} from '../src/client/service.ts'
 import type { Context, SidebarSessionList } from '../src/context-types.ts'
 
 class FakeWebSocket {
@@ -45,10 +58,79 @@ function makeSessionFeed(initial: SidebarSessionList) {
 
 type SessionFeed = ReturnType<typeof makeSessionFeed>
 
+/** One recorded native-surface open. */
+interface NativeOpen {
+  sessionId: string
+  kind: string
+  params: unknown
+  revealIfOpened: boolean
+}
+
+/** The native right Sidebar, replaced by a recording stand-in: the shell's
+ *  opens must reach THIS surface, not the plugin's own layout. */
+interface NativeSurfaceSpy {
+  surface: SidebarSurface
+  opens: NativeOpen[]
+}
+
+function makeNativeSurfaceSpy(): NativeSurfaceSpy {
+  const opens: NativeOpen[] = []
+  return {
+    opens,
+    surface: {
+      openTab: input => { opens.push({ ...input }) },
+      openResource: () => {},
+      fileAddress: (sessionId, cwd, path) => `addr://${sessionId}${cwd ?? ''}${path}`,
+      close: () => undefined,
+      update: () => false,
+      activate: () => false,
+      has: () => false,
+    },
+  }
+}
+
+/** `ctx.sidebarRight`, replaced by a stand-in column: `isExpanded` reports the
+ *  current state, `toggleExpanded` flips it and counts the calls. */
+interface NativeColumnSpy {
+  face: { isExpanded: () => boolean; toggleExpanded: () => void }
+  toggles: number
+}
+
+function makeNativeColumnSpy(expanded: boolean): NativeColumnSpy {
+  const spy = {
+    toggles: 0,
+    expanded,
+    face: {} as { isExpanded: () => boolean; toggleExpanded: () => void },
+  }
+  spy.face = {
+    isExpanded: () => spy.expanded,
+    toggleExpanded: () => {
+      spy.toggles += 1
+      spy.expanded = !spy.expanded
+    },
+  }
+  return spy
+}
+
+/** Stands in for the Tasks page: its node click is the jump gesture that arms
+ *  the shell's jump-back (fired once, like a real click). */
+function JumpHarness({ onSubagentJump }: TabComponentProps): ReactNode {
+  const fired = useRef(false)
+  useEffect(() => {
+    if (fired.current) return
+    fired.current = true
+    onSubagentJump?.('child')
+  }, [onSubagentJump])
+  return null
+}
+
 interface MountedSidebar {
   store: SidebarStore
   service: BetterSidebarService
   feed: SessionFeed
+  surface: NativeSurfaceSpy
+  column: NativeColumnSpy
+  sessionId: string
   unmount: () => void
 }
 
@@ -59,7 +141,11 @@ function setViewport(width: number): void {
   Object.defineProperty(window, 'innerWidth', { configurable: true, value: width })
 }
 
-function mountSidebar(width: number, bottomOpen = false): MountedSidebar {
+function mountSidebar(
+  width: number,
+  bottomOpen = false,
+  options: { columnExpanded?: boolean } = {},
+): MountedSidebar {
   setViewport(width)
   vi.stubGlobal('WebSocket', FakeWebSocket)
   const sessionId = `auto-activation-${++sessionSeq}`
@@ -76,13 +162,18 @@ function mountSidebar(width: number, bottomOpen = false): MountedSidebar {
   store.setSession(sessionId)
   store.reduce(state => ({ ...state, bottomOpen }))
   const service = createBetterSidebarService(store)
-  service.registerTab({ id: 'subagent', title: 'Subagent', component: () => null })
+  const surface = makeNativeSurfaceSpy()
+  service.setSurface(surface.surface)
+  service.registerTab({ id: 'subagent', title: 'Subagent', component: JumpHarness })
+  const column = makeNativeColumnSpy(options.columnExpanded ?? false)
   const localeSnapshot = { active: 'en' }
   const ctx = {
     locale: { subscribe: () => () => {}, getSnapshot: () => localeSnapshot },
     sessions: { list: feed },
     betterSidebar: service,
-    get: (name: string) => name === 'betterSidebar' ? service : undefined,
+    get: (name: string) => name === 'betterSidebar'
+      ? service
+      : name === 'sidebarRight' ? column.face : undefined,
   } as unknown as Context
   const container = document.createElement('div')
   document.body.append(container)
@@ -92,6 +183,9 @@ function mountSidebar(width: number, bottomOpen = false): MountedSidebar {
     store,
     service,
     feed,
+    surface,
+    column,
+    sessionId,
     unmount: () => {
       act(() => { root.unmount() })
       container.remove()
@@ -101,6 +195,18 @@ function mountSidebar(width: number, bottomOpen = false): MountedSidebar {
   return result
 }
 
+type ActivitySource = 'subagent' | 'job'
+
+/** Deliver one piece of background activity through the host's own feeds. */
+function publishActivity(sidebar: MountedSidebar, source: ActivitySource): void {
+  if (source === 'job') {
+    publishJob(sidebar)
+    return
+  }
+  publishSubagent(sidebar)
+  flushSubagentDebounce()
+}
+
 function publishSubagent(sidebar: MountedSidebar): void {
   const before = sidebar.feed.getSnapshot()
   const sessionId = before.current!
@@ -145,14 +251,44 @@ function publishJob(sidebar: MountedSidebar): void {
   })
 }
 
-function expectSubagentFocused(sidebar: MountedSidebar): void {
+/** Switch the conversation to the child session the Tasks page jumped to. */
+function switchToChild(sidebar: MountedSidebar): void {
+  const before = sidebar.feed.getSnapshot()
+  const parent = before.current!
+  act(() => {
+    sidebar.feed.set({
+      ...before,
+      current: 'child',
+      byId: {
+        ...before.byId,
+        child: {
+          id: 'child',
+          displayTitle: 'Worker',
+          origin: 'subagent',
+          parentId: parent,
+          running: true,
+        },
+      },
+    })
+  })
+}
+
+/** The Tasks page landed in the native right Sidebar (the default open). */
+function expectNativeTasksOpen(sidebar: MountedSidebar, sessionId: string): void {
+  expect(sidebar.surface.opens).toEqual([{
+    sessionId,
+    kind: 'subagent',
+    params: expect.objectContaining({ title: expect.any(String) }),
+    revealIfOpened: true,
+  }])
+}
+
+/** The plugin's own bottom workbench kept its own state and gained no tab. */
+function expectWorkbenchUntouched(sidebar: MountedSidebar, open = false): void {
   const state = sidebar.store.getSnapshot().state!
-  const pane = firstLeaf(state.bottomSplits)
+  expect(state.bottomOpen).toBe(open)
-  expect(state.bottomOpen).toBe(true)
-  expect(state.activePane).toBe(pane.id)
   expect(allLeaves(state.bottomSplits).flatMap(leaf => leaf.tabs)
-    .filter(tab => tab.type === 'subagent')).toHaveLength(1)
+    .filter(tab => tab.type === 'subagent')).toHaveLength(0)
-  expect(pane.tabs.find(tab => tab.id === pane.active)?.type).toBe('subagent')
 }
 
 beforeEach(() => {
@@ -176,33 +312,57 @@ describe('Sidebar background-activity auto-activation (#162)', () => {
     { source: 'job', width: 390 },
     { source: 'subagent', width: 1024 },
     { source: 'job', width: 1024 },
-  ] as const)('$source activation at $width px focuses the Tasks page in the workbench', ({ source, width }) => {
+  ] as const)('$source activation at $width px activates the Tasks page in the native Sidebar', ({ source, width }) => {
     const sidebar = mountSidebar(width)
-    if (source === 'subagent') {
+    publishActivity(sidebar, source)
-      publishSubagent(sidebar)
+    expectNativeTasksOpen(sidebar, sidebar.sessionId)
-      flushSubagentDebounce()
+    expectWorkbenchUntouched(sidebar)
-    } else {
+    // Parking is the narrow-viewport half of the same promise.
-      publishJob(sidebar)
+    expect(sidebar.column.toggles).toBe(width < 768 ? 1 : 0)
-    }
-    expectSubagentFocused(sidebar)
   })
 
-  it.each(['subagent', 'job'] as const)('%s activation keeps an already-open workbench open', (source) => {
+  it.each(['subagent', 'job'] as const)('%s activation leaves a narrow fullscreen column to the park', (source) => {
-    const sidebar = mountSidebar(390, true)
+    const sidebar = mountSidebar(390)
-    if (source === 'subagent') {
+    publishActivity(sidebar, source)
-      publishSubagent(sidebar)
+    expect(sidebar.column.toggles).toBe(1)
-      flushSubagentDebounce()
-    } else {
-      publishJob(sidebar)
-    }
-    expectSubagentFocused(sidebar)
   })
 
-  it('a resize between arming and firing the debounce does not change the landing', () => {
+  it('a narrow column the user already expanded is not closed under them', () => {
+    const sidebar = mountSidebar(390, false, { columnExpanded: true })
+    publishActivity(sidebar, 'subagent')
+    expectNativeTasksOpen(sidebar, sidebar.sessionId)
+    expect(sidebar.column.toggles).toBe(0)
+  })
+
+  it('reads the viewport when the debounced activation fires, not when it arms', () => {
     const sidebar = mountSidebar(1024)
     publishSubagent(sidebar)
     setViewport(390)
     flushSubagentDebounce()
-    expectSubagentFocused(sidebar)
+    expectNativeTasksOpen(sidebar, sidebar.sessionId)
+    expect(sidebar.column.toggles).toBe(1)
+  })
+
+  it('leaves an already-open bottom workbench open and untouched', () => {
+    const sidebar = mountSidebar(1024, true)
+    publishActivity(sidebar, 'subagent')
+    expectNativeTasksOpen(sidebar, sidebar.sessionId)
+    expectWorkbenchUntouched(sidebar, true)
+  })
+
+  it('the topology jump-back opens the Tasks page for the child session and never parks it', () => {
+    const sidebar = mountSidebar(390)
+    // The Tasks page the user opened in the workbench (its own + menu) is what
+    // arms the jump: its node click records the child session.
+    act(() => {
+      sidebar.service.openTab(
+        { type: 'subagent', title: 'Tasks', target: 'bottom' },
+        { sessionId: sidebar.sessionId },
+      )
+    })
+    expect(sidebar.store.getSnapshot().state!.bottomOpen).toBe(true)
+    switchToChild(sidebar)
+    expectNativeTasksOpen(sidebar, 'child')
+    expect(sidebar.column.toggles).toBe(0)
   })
 })