diff --git a/src/client/Sidebar.tsx b/src/client/Sidebar.tsx
index e558407..8e07f9e 100644
--- a/src/client/Sidebar.tsx
+++ b/src/client/Sidebar.tsx
@@ -32,12 +32,12 @@ import { useCallback, useEffect, useMemo, useRef, useState, type DragEvent as Re
 import { useSyncExternalStore } from 'react'
 import clsx from 'clsx'
 import { IconCloseFill14, Tooltip } from '@deepseek-ai/dsh-client-ui-primitives'
-import type { Context, SidebarSessionList } from '../context-types.ts'
+import type { Context } from '../context-types.ts'
 import { appendToDraft, insertFileReference } from './conversation-draft.ts'
 import {
   BOTTOM_MIN, PANEL_MIN, agentUuidOf, closeFloatByTab, closeTab, dockFloat, firstLeaf, floatTab,
   isAgentTabId, leafWithTab, migrateBottomTabs,
-  moveFloat, moveTab, moveTabToEdge, openDiffTab, raiseFloat, reconcileAgentTerminals,
+  moveFloat, moveTab, moveTabToEdge, openDiffTab, raiseFloat,
   resizeFloat, resizeSplitIn, setBottomHeight, setTabPin, setWidth, toggleBottomPanel, toggleExpanded, togglePanel,
   type DropZone, type SidebarState, type SidebarStore, type SidebarTab,
 } from './state.ts'
@@ -52,29 +52,14 @@ import { getShellPreset } from './shell-presets.ts'
 import { computeTitleBarStrip } from './titlebar-strip.ts'
 import { TabContent, buildNewTabOptions } from './sidebar/TabContent.tsx'
 import { useCenterColumn } from './sidebar/use-center-column.ts'
+import { useHostFeeds } from './sidebar/use-host-feeds.ts'
 import { TAB_DRAG_TYPE, parseDrag, type TabDragPayload } from './TabBar.tsx'
 import { FreeWindow } from './FreeWindow.tsx'
 import { relativeTo } from './paths.ts'
-import { detectNewDirectSubagent } from './subagent-detect.ts'
-import { detectNewJob } from './subagent-jobs.ts'
 import { t } from './locales.ts'
 import { api } from './api.ts'
 import css from './sidebar.module.css'
 
-/** How many consecutive reconnect failures stop the agent-terminals push loop
- * (mirror of the terminal view's own cap; the loop restarts on session switch). */
-const FAILURE_LIMIT = 3
-
-/**
- * Subagent auto-open debounce (ms). The host delivers a new child's origin
- * and its title in SEPARATE frames: a Side Chat thread's first visible
- * frame still shows a fallback title (no 'Side: ' prefix), so an immediate
- * 0→N decision mistakes it for a genuine subagent and pops the task page.
- * The trigger therefore re-evaluates against the live snapshot once the
- * title frame has had time to land.
- */
-const AUTO_OPEN_DEBOUNCE_MS = 500
-
 /**
  * OS file drags over the sidebar belong to the sidebar, not to the chat:
  * DSH's composer (InputBar) listens for file drags on the DOCUMENT and
@@ -358,235 +343,11 @@ export function Sidebar(props: { ctx: Context; store: SidebarStore }) {
     [state, ctx, sessionId, cwd],
   )
 
-  /**
-   * Agent terminals push: subscribe to the host's live list of agent-owned
-   * terminals for this session (created by the model through the
-   * `terminal_create` tool). The host pushes a JSON array on every
-   * create / close / exit; the sidebar reconciles the list into tabs
-   * (id `agent:<uuid>`, title from the agent). A disconnected socket
-   * retries with a short backoff so a refresh or transient drop reattaches
-   * the same shell without losing the agent's work — capped like the
-   * terminal view's own reconnect loop, so a refused endpoint never spins
-   * forever (the next session switch restarts the loop).
-   * While the terminal tab type is disabled in settings, pushes are
-   * ignored (no auto-added tabs); re-enabling makes the next push converge.
-   */
-  useEffect(() => {
-    if (sessionId === undefined) return
-    let socket: WebSocket | null = null
-    let retry: number | undefined
-    let closed = false
-    let failures = 0
-    const connect = (): void => {
-      if (closed) return
-      const url = new URL('/sidebar/ws/agent-terminals', location.origin)
-      url.protocol = url.protocol === 'https:' ? 'wss:' : 'ws:'
-      url.search = new URLSearchParams({ sessionId }).toString()
-      socket = new WebSocket(url.toString())
-      socket.onmessage = (event) => {
-        if (typeof event.data !== 'string') return
-        try {
-          const list = JSON.parse(event.data) as Array<{ uuid: string; title: string; command: string; exited: boolean }>
-          if (!Array.isArray(list)) return
-          store.reduce(s => ctx.get('betterSidebar')?.isTabEnabled('terminal') === false
-            ? s
-            : reconcileAgentTerminals(s, list))
-        } catch {
-          // Malformed push: ignore (the next push will reconcile).
-        }
-      }
-      socket.onclose = () => {
-        if (closed) return
-        failures += 1
-        if (failures >= FAILURE_LIMIT) {
-          console.error('[dsh-better-sidebar] agent-terminals connection failed; stopping reconnect loop', sessionId)
-          return
-        }
-        retry = window.setTimeout(connect, 2000)
-      }
-      socket.onerror = () => { socket?.close() }
-    }
-    connect()
-    return () => {
-      closed = true
-      window.clearTimeout(retry)
-      socket?.close()
-    }
-  }, [sessionId, ctx, store])
-
-  /**
-   * Agent opens push: subscribe to the host's `sidebar_open` requests for
-   * this session (the model actively opens a file / folder / HTTP(S) page).
-   * The host pushes one JSON request per open; the sidebar routes it to the
-   * matching built-in tab: a file opens in the editor (per-path dedupe), a
-   * folder opens a file window whose tree is rooted at the folder
-   * (`meta.dir`), and a URL opens in the browser tab. A disconnected socket
-   * retries with a short backoff (mirror of the agent-terminals loop): the
-   * host queue keeps undelivered requests and replays them on the first
-   * attach, so a refresh or a session switch lands the opens the model
-   * queued while no view was connected.
-   * While the side-card setting is off, pushes are ignored as a defensive
-   * gate — the host already unregisters the tool and drains the queue.
-   */
-  useEffect(() => {
-    if (sessionId === undefined) return
-    let socket: WebSocket | null = null
-    let retry: number | undefined
-    let closed = false
-    let failures = 0
-    const connect = (): void => {
-      if (closed) return
-      const url = new URL('/sidebar/ws/agent-opens', location.origin)
-      url.protocol = url.protocol === 'https:' ? 'wss:' : 'ws:'
-      url.search = new URLSearchParams({ sessionId }).toString()
-      socket = new WebSocket(url.toString())
-      socket.onmessage = (event) => {
-        if (typeof event.data !== 'string') return
-        try {
-          const request = JSON.parse(event.data) as { kind?: unknown; target?: unknown; title?: unknown }
-          if (request === null || typeof request !== 'object') return
-          if (request.kind !== 'file' && request.kind !== 'folder' && request.kind !== 'url') return
-          if (typeof request.target !== 'string' || request.target === '') return
-          if (store.getPrefs().agentOpenTools !== true) return
-          const scope = { sessionId }
-          const title = typeof request.title === 'string' && request.title !== '' ? request.title : undefined
-          if (request.kind === 'url') {
-            ctx.get('betterSidebar')?.openTab({ type: 'browser', url: request.target, title }, scope)
-          } else if (request.kind === 'folder') {
-            ctx.get('betterSidebar')?.openTab({
-              type: 'editor',
-              title,
-              path: request.target,
-              id: `editor:${request.target}`,
-              meta: { dir: true },
-            }, scope)
-          } else {
-            ctx.get('betterSidebar')?.openFile(scope, request.target, title)
-          }
-        } catch {
-          // Malformed push: ignore (the next push carries its own request).
-        }
-      }
-      socket.onclose = () => {
-        if (closed) return
-        failures += 1
-        if (failures >= FAILURE_LIMIT) {
-          console.error('[dsh-better-sidebar] agent-opens connection failed; stopping reconnect loop', sessionId)
-          return
-        }
-        retry = window.setTimeout(connect, 2000)
-      }
-      socket.onerror = () => { socket?.close() }
-    }
-    connect()
-    return () => {
-      closed = true
-      window.clearTimeout(retry)
-      socket?.close()
-    }
-  }, [sessionId, ctx, store])
-
-  /**
-   * 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
-   * place or raise an existing free window; a new tab lands in the right pane
-   * and is never duplicated. On wide viewports the right panel also expands;
-   * on narrow viewports background activity never forces the full-screen
-   * drawer open over the chat.
-   * Switching to a session that already has subagents never triggers — its
-   * baseline starts at the current count — so a deliberate layout is never
-   * fought.
-   *
-   * The decision is DEBOUNCED (AUTO_OPEN_DEBOUNCE_MS): a Side Chat thread
-   * is also a subagent-origin child, and its 'Side: ' title lands one frame
-   * after its origin — an immediate check would misread that first frame as
-   * a new subagent and pop this page on every thread creation. The timer
-   * re-evaluates the ORIGINAL baseline against the live snapshot; by then
-   * the title filter (isSideThreadSummary) sees the settled label.
-   */
-  const listBaselineRef = useRef<SidebarSessionList | undefined>(undefined)
-  const autoOpenPendingRef = useRef<{ baseline: SidebarSessionList; timer: number } | null>(null)
-  useEffect(() => {
-    const prev = listBaselineRef.current
-    listBaselineRef.current = sessionList
-    if (sessionId === undefined || prev === undefined) return
-    if (autoOpenPendingRef.current !== null) return
-    if (!detectNewDirectSubagent(prev, sessionList, sessionId)) return
-    const baseline = prev
-    const timer = window.setTimeout(() => {
-      autoOpenPendingRef.current = null
-      if (!detectNewDirectSubagent(baseline, ctx.sessions.list.getSnapshot(), sessionId)) return
-      if (!store.getPrefs().autoOpenSubagent) return
-      if (ctx.get('betterSidebar')?.isTabEnabled('subagent') === false) return
-      // Read the viewport when the delayed activation fires: a resize while
-      // the debounce is armed must not let background activity force the
-      // narrow full-screen drawer open over the chat.
-      if (!isNarrowWidth(window.innerWidth)) {
-        store.reduce(s => s.panelOpen ? s : togglePanel(s))
-      }
-      // Choose the right panel as the landing pane for a newly created Tasks
-      // tab. Single-instance dedupe still activates an existing pane tab in
-      // place or raises an existing free window.
-      store.reduce(s => ({ ...s, activePane: firstLeaf(s.splits).id }))
-      ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
-    }, AUTO_OPEN_DEBOUNCE_MS)
-    autoOpenPendingRef.current = { baseline, timer }
-  }, [sessionList, sessionId, store, ctx])
-
-  // A session switch (or unmount) voids any armed auto-open recheck.
-  useEffect(() => () => {
-    const pending = autoOpenPendingRef.current
-    if (pending !== null) window.clearTimeout(pending.timer)
-    autoOpenPendingRef.current = null
-  }, [sessionId])
-
-  /**
-   * 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
-   * only on wide viewports. Unlike the subagent trigger (0 → N only), ANY
-   * new job id triggers: the agent may start several jobs in 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(() => {
-    const prev = jobBaselineRef.current
-    jobBaselineRef.current = sessionList
-    if (sessionId === undefined || prev === undefined) return
-    if (!detectNewJob(prev, sessionList, sessionId)) return
-    if (!store.getPrefs().autoOpenJobs) return
-    if (ctx.get('betterSidebar')?.isTabEnabled('subagent') === false) return
-    if (!isNarrowWidth(window.innerWidth)) {
-      store.reduce(s => s.panelOpen ? s : togglePanel(s))
-    }
-    store.reduce(s => ({ ...s, activePane: firstLeaf(s.splits).id }))
-    ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
-  }, [sessionList, sessionId, store, ctx])
-
-  /**
-   * Topology jump-back: clicking a subagent node on the Subagent page calls
-   * the official `openSubagent`, which switches the sidebar to that child
-   * 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
-   * the panel first if it is collapsed). Only this explicit node 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
-    store.reduce(s => s.panelOpen ? s : togglePanel(s))
-    store.reduce(s => ({ ...s, activePane: firstLeaf(s.splits).id }))
-    ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
-  }, [sessionId, store, ctx])
+  // Host feeds (sidebar/use-host-feeds.ts): the agent-terminals / agent-opens
+  // WebSocket pushes and the subagent / background-job auto-activation
+  // triggers, all keyed on the current session. The jump-back ref is the one
+  // piece the render side consumes (renderTab's onSubagentJump arms it).
+  const { subagentJumpRef } = useHostFeeds({ ctx, store, sessionList, sessionId })
 
   /**
    /**
diff --git a/src/client/sidebar/use-host-feeds.ts b/src/client/sidebar/use-host-feeds.ts
new file mode 100644
index 0000000..0028690
--- /dev/null
+++ b/src/client/sidebar/use-host-feeds.ts
@@ -0,0 +1,269 @@
+/**
+ * Host-feed subscriptions (extracted from Sidebar.tsx, behavior identical):
+ * the WebSocket pushes (agent terminals, agent opens) and the session-list
+ * driven auto-activation triggers (subagent, background jobs, topology
+ * jump-back). All of it reacts to the host's live feeds for the CURRENT
+ * session; the sidebar shell only consumes the returned jump-back ref.
+ */
+import { useEffect, useRef } from 'react'
+import type { Context, SidebarSessionList } from '../../context-types.ts'
+import { firstLeaf, reconcileAgentTerminals, togglePanel, 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'
+
+/** How many consecutive reconnect failures stop the agent-terminals push loop
+ * (mirror of the terminal view's own cap; the loop restarts on session switch). */
+const FAILURE_LIMIT = 3
+
+/**
+ * Subagent auto-open debounce (ms). The host delivers a new child's origin
+ * and its title in SEPARATE frames: a Side Chat thread's first visible
+ * frame still shows a fallback title (no 'Side: ' prefix), so an immediate
+ * 0→N decision mistakes it for a genuine subagent and pops the task page.
+ * The trigger therefore re-evaluates against the live snapshot once the
+ * title frame has had time to land.
+ */
+const AUTO_OPEN_DEBOUNCE_MS = 500
+
+export function useHostFeeds(feeds: {
+  ctx: Context
+  store: SidebarStore
+  sessionList: SidebarSessionList
+  sessionId: string | undefined
+}): { subagentJumpRef: { current: string | undefined } } {
+  const { ctx, store, sessionList, sessionId } = feeds
+
+  /**
+   * Agent terminals push: subscribe to the host's live list of agent-owned
+   * terminals for this session (created by the model through the
+   * `terminal_create` tool). The host pushes a JSON array on every
+   * create / close / exit; the sidebar reconciles the list into tabs
+   * (id `agent:<uuid>`, title from the agent). A disconnected socket
+   * retries with a short backoff so a refresh or transient drop reattaches
+   * the same shell without losing the agent's work — capped like the
+   * terminal view's own reconnect loop, so a refused endpoint never spins
+   * forever (the next session switch restarts the loop).
+   * While the terminal tab type is disabled in settings, pushes are
+   * ignored (no auto-added tabs); re-enabling makes the next push converge.
+   */
+  useEffect(() => {
+    if (sessionId === undefined) return
+    let socket: WebSocket | null = null
+    let retry: number | undefined
+    let closed = false
+    let failures = 0
+    const connect = (): void => {
+      if (closed) return
+      const url = new URL('/sidebar/ws/agent-terminals', location.origin)
+      url.protocol = url.protocol === 'https:' ? 'wss:' : 'ws:'
+      url.search = new URLSearchParams({ sessionId }).toString()
+      socket = new WebSocket(url.toString())
+      socket.onmessage = (event) => {
+        if (typeof event.data !== 'string') return
+        try {
+          const list = JSON.parse(event.data) as Array<{ uuid: string; title: string; command: string; exited: boolean }>
+          if (!Array.isArray(list)) return
+          store.reduce(s => ctx.get('betterSidebar')?.isTabEnabled('terminal') === false
+            ? s
+            : reconcileAgentTerminals(s, list))
+        } catch {
+          // Malformed push: ignore (the next push will reconcile).
+        }
+      }
+      socket.onclose = () => {
+        if (closed) return
+        failures += 1
+        if (failures >= FAILURE_LIMIT) {
+          console.error('[dsh-better-sidebar] agent-terminals connection failed; stopping reconnect loop', sessionId)
+          return
+        }
+        retry = window.setTimeout(connect, 2000)
+      }
+      socket.onerror = () => { socket?.close() }
+    }
+    connect()
+    return () => {
+      closed = true
+      window.clearTimeout(retry)
+      socket?.close()
+    }
+  }, [sessionId, ctx, store])
+
+  /**
+   * Agent opens push: subscribe to the host's `sidebar_open` requests for
+   * this session (the model actively opens a file / folder / HTTP(S) page).
+   * The host pushes one JSON request per open; the sidebar routes it to the
+   * matching built-in tab: a file opens in the editor (per-path dedupe), a
+   * folder opens a file window whose tree is rooted at the folder
+   * (`meta.dir`), and a URL opens in the browser tab. A disconnected socket
+   * retries with a short backoff (mirror of the agent-terminals loop): the
+   * host queue keeps undelivered requests and replays them on the first
+   * attach, so a refresh or a session switch lands the opens the model
+   * queued while no view was connected.
+   * While the side-card setting is off, pushes are ignored as a defensive
+   * gate — the host already unregisters the tool and drains the queue.
+   */
+  useEffect(() => {
+    if (sessionId === undefined) return
+    let socket: WebSocket | null = null
+    let retry: number | undefined
+    let closed = false
+    let failures = 0
+    const connect = (): void => {
+      if (closed) return
+      const url = new URL('/sidebar/ws/agent-opens', location.origin)
+      url.protocol = url.protocol === 'https:' ? 'wss:' : 'ws:'
+      url.search = new URLSearchParams({ sessionId }).toString()
+      socket = new WebSocket(url.toString())
+      socket.onmessage = (event) => {
+        if (typeof event.data !== 'string') return
+        try {
+          const request = JSON.parse(event.data) as { kind?: unknown; target?: unknown; title?: unknown }
+          if (request === null || typeof request !== 'object') return
+          if (request.kind !== 'file' && request.kind !== 'folder' && request.kind !== 'url') return
+          if (typeof request.target !== 'string' || request.target === '') return
+          if (store.getPrefs().agentOpenTools !== true) return
+          const scope = { sessionId }
+          const title = typeof request.title === 'string' && request.title !== '' ? request.title : undefined
+          if (request.kind === 'url') {
+            ctx.get('betterSidebar')?.openTab({ type: 'browser', url: request.target, title }, scope)
+          } else if (request.kind === 'folder') {
+            ctx.get('betterSidebar')?.openTab({
+              type: 'editor',
+              title,
+              path: request.target,
+              id: `editor:${request.target}`,
+              meta: { dir: true },
+            }, scope)
+          } else {
+            ctx.get('betterSidebar')?.openFile(scope, request.target, title)
+          }
+        } catch {
+          // Malformed push: ignore (the next push carries its own request).
+        }
+      }
+      socket.onclose = () => {
+        if (closed) return
+        failures += 1
+        if (failures >= FAILURE_LIMIT) {
+          console.error('[dsh-better-sidebar] agent-opens connection failed; stopping reconnect loop', sessionId)
+          return
+        }
+        retry = window.setTimeout(connect, 2000)
+      }
+      socket.onerror = () => { socket?.close() }
+    }
+    connect()
+    return () => {
+      closed = true
+      window.clearTimeout(retry)
+      socket?.close()
+    }
+  }, [sessionId, ctx, store])
+
+  /**
+   * 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
+   * place or raise an existing free window; a new tab lands in the right pane
+   * and is never duplicated. On wide viewports the right panel also expands;
+   * on narrow viewports background activity never forces the full-screen
+   * drawer open over the chat.
+   * Switching to a session that already has subagents never triggers — its
+   * baseline starts at the current count — so a deliberate layout is never
+   * fought.
+   *
+   * The decision is DEBOUNCED (AUTO_OPEN_DEBOUNCE_MS): a Side Chat thread
+   * is also a subagent-origin child, and its 'Side: ' title lands one frame
+   * after its origin — an immediate check would misread that first frame as
+   * a new subagent and pop this page on every thread creation. The timer
+   * re-evaluates the ORIGINAL baseline against the live snapshot; by then
+   * the title filter (isSideThreadSummary) sees the settled label.
+   */
+  const listBaselineRef = useRef<SidebarSessionList | undefined>(undefined)
+  const autoOpenPendingRef = useRef<{ baseline: SidebarSessionList; timer: number } | null>(null)
+  useEffect(() => {
+    const prev = listBaselineRef.current
+    listBaselineRef.current = sessionList
+    if (sessionId === undefined || prev === undefined) return
+    if (autoOpenPendingRef.current !== null) return
+    if (!detectNewDirectSubagent(prev, sessionList, sessionId)) return
+    const baseline = prev
+    const timer = window.setTimeout(() => {
+      autoOpenPendingRef.current = null
+      if (!detectNewDirectSubagent(baseline, ctx.sessions.list.getSnapshot(), sessionId)) return
+      if (!store.getPrefs().autoOpenSubagent) return
+      if (ctx.get('betterSidebar')?.isTabEnabled('subagent') === false) return
+      // Read the viewport when the delayed activation fires: a resize while
+      // the debounce is armed must not let background activity force the
+      // narrow full-screen drawer open over the chat.
+      if (!isNarrowWidth(window.innerWidth)) {
+        store.reduce(s => s.panelOpen ? s : togglePanel(s))
+      }
+      // Choose the right panel as the landing pane for a newly created Tasks
+      // tab. Single-instance dedupe still activates an existing pane tab in
+      // place or raises an existing free window.
+      store.reduce(s => ({ ...s, activePane: firstLeaf(s.splits).id }))
+      ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
+    }, AUTO_OPEN_DEBOUNCE_MS)
+    autoOpenPendingRef.current = { baseline, timer }
+  }, [sessionList, sessionId, store, ctx])
+
+  // A session switch (or unmount) voids any armed auto-open recheck.
+  useEffect(() => () => {
+    const pending = autoOpenPendingRef.current
+    if (pending !== null) window.clearTimeout(pending.timer)
+    autoOpenPendingRef.current = null
+  }, [sessionId])
+
+  /**
+   * 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
+   * only on wide viewports. Unlike the subagent trigger (0 → N only), ANY
+   * new job id triggers: the agent may start several jobs in 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(() => {
+    const prev = jobBaselineRef.current
+    jobBaselineRef.current = sessionList
+    if (sessionId === undefined || prev === undefined) return
+    if (!detectNewJob(prev, sessionList, sessionId)) return
+    if (!store.getPrefs().autoOpenJobs) return
+    if (ctx.get('betterSidebar')?.isTabEnabled('subagent') === false) return
+    if (!isNarrowWidth(window.innerWidth)) {
+      store.reduce(s => s.panelOpen ? s : togglePanel(s))
+    }
+    store.reduce(s => ({ ...s, activePane: firstLeaf(s.splits).id }))
+    ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
+  }, [sessionList, sessionId, store, ctx])
+
+  /**
+   * Topology jump-back: clicking a subagent node on the Subagent page calls
+   * the official `openSubagent`, which switches the sidebar to that child
+   * 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
+   * the panel first if it is collapsed). Only this explicit node 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
+    store.reduce(s => s.panelOpen ? s : togglePanel(s))
+    store.reduce(s => ({ ...s, activePane: firstLeaf(s.splits).id }))
+    ctx.get('betterSidebar')?.openTab({ type: 'subagent', title: t('subagent') })
+  }, [sessionId, store, ctx])
+
+  return { subagentJumpRef }
+}