diff --git a/apps/desktop/src/app/agents/index.tsx b/apps/desktop/src/app/agents/index.tsx
index 0281eb1bc77..f58d211293e 100644
--- a/apps/desktop/src/app/agents/index.tsx
+++ b/apps/desktop/src/app/agents/index.tsx
@@ -5,7 +5,8 @@ import { Activity, AlertCircle, Layers3, Loader2, type LucideIcon, RefreshCw, Sp
 import { cn } from '@/lib/utils'
 import { $desktopActionTasks, buildRailTasks, type RailTask, type RailTaskStatus } from '@/store/activity'
 import { $previewServerRestart } from '@/store/preview'
-import { $sessions, $workingSessionIds } from '@/store/session'
+import { $activeSessionId, $sessions, $workingSessionIds } from '@/store/session'
+import { $subagentsBySession, buildSubagentTree, type SubagentNode, type SubagentStatus } from '@/store/subagents'
 
 import { useRouteEnumParam } from '../hooks/use-route-enum-param'
 import { OverlayCard } from '../overlays/overlay-chrome'
@@ -49,10 +50,12 @@ interface AgentsViewProps {
 export function AgentsView({ initialSection = 'tree', onClose }: AgentsViewProps) {
   const [section, setSection] = useRouteEnumParam('section', SECTION_IDS, initialSection)
 
+  const activeSessionId = useStore($activeSessionId)
   const sessions = useStore($sessions)
   const workingSessionIds = useStore($workingSessionIds)
   const previewRestart = useStore($previewServerRestart)
   const desktopActionTasks = useStore($desktopActionTasks)
+  const subagentsBySession = useStore($subagentsBySession)
 
   const activityTasks = useMemo(
     () => buildRailTasks(workingSessionIds, sessions, previewRestart, desktopActionTasks),
@@ -60,6 +63,8 @@ export function AgentsView({ initialSection = 'tree', onClose }: AgentsViewProps
   )
 
   const active = SECTIONS.find(s => s.id === section) ?? SECTIONS[0]!
+  const activeSubagents = activeSessionId ? (subagentsBySession[activeSessionId] ?? []) : []
+  const tree = useMemo(() => buildSubagentTree(activeSubagents), [activeSubagents])
 
   return (
     <OverlayView closeLabel="Close agents" onClose={onClose}>
@@ -82,13 +87,91 @@ export function AgentsView({ initialSection = 'tree', onClose }: AgentsViewProps
             <p className="text-xs text-muted-foreground">{active.description}</p>
           </header>
 
-          {section === 'activity' ? <ActivityList tasks={activityTasks} /> : <SectionStub label={active.label} />}
+          {section === 'tree' ? (
+            <SubagentTree tree={tree} />
+          ) : section === 'activity' ? (
+            <ActivityList tasks={activityTasks} />
+          ) : (
+            <SectionStub label={active.label} />
+          )}
         </OverlayMain>
       </OverlaySplitLayout>
     </OverlayView>
   )
 }
 
+const STATUS_CLASS: Record<SubagentStatus, string> = {
+  completed: 'text-emerald-500',
+  failed: 'text-destructive',
+  interrupted: 'text-amber-500',
+  queued: 'text-muted-foreground',
+  running: 'text-primary'
+}
+
+function SubagentTree({ tree }: { tree: SubagentNode[] }) {
+  if (tree.length === 0) {
+    return (
+      <OverlayCard className="grid place-items-center gap-3 px-6 py-12 text-center">
+        <Sparkles className="size-6 text-muted-foreground/70" />
+        <div className="grid gap-1">
+          <p className="text-sm font-medium text-foreground">No live subagents</p>
+          <p className="max-w-md text-xs leading-relaxed text-muted-foreground">
+            When a turn delegates work, child agents appear here as a live spawn tree.
+          </p>
+        </div>
+      </OverlayCard>
+    )
+  }
+
+  return (
+    <div className="grid gap-2 overflow-y-auto pr-1">
+      {tree.map(node => (
+        <SubagentRow key={node.id} node={node} />
+      ))}
+    </div>
+  )
+}
+
+function SubagentRow({ node, depth = 0 }: { node: SubagentNode; depth?: number }) {
+  const running = node.status === 'running' || node.status === 'queued'
+
+  return (
+    <OverlayCard className="px-3 py-2" style={{ marginLeft: depth ? `${Math.min(depth, 4) * 1.25}rem` : undefined }}>
+      <div className="flex items-start gap-2">
+        {running ? (
+          <Loader2 className="mt-0.5 size-3.5 shrink-0 animate-spin text-primary" />
+        ) : (
+          <Sparkles className={cn('mt-0.5 size-3.5 shrink-0', STATUS_CLASS[node.status])} />
+        )}
+        <div className="min-w-0 flex-1">
+          <div className="flex min-w-0 items-center gap-2">
+            <div className="truncate text-sm font-medium text-foreground">{node.goal}</div>
+            <span className={cn('shrink-0 text-[0.65rem]', STATUS_CLASS[node.status])}>{node.status}</span>
+          </div>
+          <div className="mt-0.5 flex flex-wrap gap-x-3 gap-y-0.5 text-[0.68rem] text-muted-foreground">
+            {node.model && <span>{node.model}</span>}
+            {typeof node.durationSeconds === 'number' && <span>{node.durationSeconds.toFixed(1)}s</span>}
+            {typeof node.costUsd === 'number' && <span>${node.costUsd.toFixed(4)}</span>}
+            {typeof node.apiCalls === 'number' && <span>{node.apiCalls} calls</span>}
+          </div>
+          {(node.toolName || node.toolPreview || node.summary) && (
+            <div className="mt-1 line-clamp-2 text-xs leading-relaxed text-muted-foreground">
+              {node.summary || [node.toolName, node.toolPreview].filter(Boolean).join(' · ')}
+            </div>
+          )}
+        </div>
+      </div>
+      {node.children.length > 0 && (
+        <div className="mt-2 grid gap-2">
+          {node.children.map(child => (
+            <SubagentRow depth={depth + 1} key={child.id} node={child} />
+          ))}
+        </div>
+      )}
+    </OverlayCard>
+  )
+}
+
 function ActivityList({ tasks }: { tasks: readonly RailTask[] }) {
   if (tasks.length === 0) {
     return (
diff --git a/apps/desktop/src/app/desktop-controller.tsx b/apps/desktop/src/app/desktop-controller.tsx
index f1794d844a6..ebe54edba04 100644
--- a/apps/desktop/src/app/desktop-controller.tsx
+++ b/apps/desktop/src/app/desktop-controller.tsx
@@ -424,6 +424,7 @@ export function DesktopController() {
       {settingsOpen && (
         <Suspense fallback={null}>
           <SettingsView
+            gateway={gatewayRef.current}
             onClose={closeOverlayToPreviousRoute}
             onConfigSaved={() => {
               void refreshHermesConfig()
diff --git a/apps/desktop/src/app/session/hooks/use-message-stream.ts b/apps/desktop/src/app/session/hooks/use-message-stream.ts
index 7bd1b956e37..f30e122b693 100644
--- a/apps/desktop/src/app/session/hooks/use-message-stream.ts
+++ b/apps/desktop/src/app/session/hooks/use-message-stream.ts
@@ -31,6 +31,7 @@ import {
   setCurrentUsage,
   setTurnStartedAt
 } from '@/store/session'
+import { clearSessionSubagents, upsertSubagent } from '@/store/subagents'
 import { recordToolDiff } from '@/store/tool-diffs'
 import type { RpcEvent } from '@/types/hermes'
 
@@ -59,6 +60,14 @@ interface QueuedStreamDeltas {
 }
 
 const STREAM_DELTA_FLUSH_MS = 16
+const SUBAGENT_EVENT_TYPES = new Set([
+  'subagent.spawn_requested',
+  'subagent.start',
+  'subagent.thinking',
+  'subagent.tool',
+  'subagent.progress',
+  'subagent.complete'
+])
 
 // Anonymous progress events that carry todos but no name still belong to the
 // todo stream; named todo events are obviously routed there too.
@@ -506,6 +515,7 @@ export function useMessageStream({
         }
 
         flushQueuedDeltas(sessionId)
+        clearSessionSubagents(sessionId)
 
         if (isActiveEvent) {
           triggerHaptic('streamStart')
@@ -575,6 +585,10 @@ export function useMessageStream({
         if (typeof payload?.inline_diff === 'string' && payload.inline_diff.trim()) {
           recordToolDiff(payload.tool_id || payload.name || '', payload.inline_diff)
         }
+      } else if (SUBAGENT_EVENT_TYPES.has(event.type)) {
+        if (sessionId && payload) {
+          upsertSubagent(sessionId, payload as Record<string, unknown>, event.type === 'subagent.spawn_requested')
+        }
       } else if (event.type === 'clarify.request') {
         if (!isActiveEvent) {
           return
diff --git a/apps/desktop/src/app/settings/constants.ts b/apps/desktop/src/app/settings/constants.ts
index b58e68931d6..605737b043f 100644
--- a/apps/desktop/src/app/settings/constants.ts
+++ b/apps/desktop/src/app/settings/constants.ts
@@ -311,10 +311,11 @@ export const MODE_OPTIONS: ModeOption[] = [
   { id: 'system', label: 'System', description: 'Follow macOS appearance', icon: Monitor }
 ]
 
-export const SEARCH_PLACEHOLDER: Record<'about' | 'config' | 'gateway' | 'keys' | 'tools', string> = {
+export const SEARCH_PLACEHOLDER: Record<'about' | 'config' | 'gateway' | 'keys' | 'mcp' | 'tools', string> = {
   about: 'About Hermes Desktop',
   config: 'Search settings...',
   gateway: 'Gateway connection...',
   keys: 'Search API keys...',
+  mcp: 'Search MCP servers...',
   tools: 'Search skills and tools...'
 }
diff --git a/apps/desktop/src/app/settings/index.tsx b/apps/desktop/src/app/settings/index.tsx
index 2e40c2ff626..a15f02350d0 100644
--- a/apps/desktop/src/app/settings/index.tsx
+++ b/apps/desktop/src/app/settings/index.tsx
@@ -3,7 +3,7 @@ import { useEffect, useRef, useState } from 'react'
 
 import { getHermesConfigDefaults, getHermesConfigRecord, saveHermesConfig } from '@/hermes'
 import { triggerHaptic } from '@/lib/haptics'
-import { Globe, Info, KeyRound, Package } from '@/lib/icons'
+import { Globe, Info, KeyRound, Package, Wrench } from '@/lib/icons'
 import { notifyError } from '@/store/notifications'
 
 import { useRouteEnumParam } from '../hooks/use-route-enum-param'
@@ -18,6 +18,7 @@ import { ConfigSettings } from './config-settings'
 import { SEARCH_PLACEHOLDER, SECTIONS } from './constants'
 import { GatewaySettings } from './gateway-settings'
 import { KeysSettings } from './keys-settings'
+import { McpSettings } from './mcp-settings'
 import { ToolsSettings } from './tools-settings'
 import type { SettingsPageProps, SettingsQueryKey, SettingsView as SettingsViewId } from './types'
 
@@ -25,11 +26,12 @@ const SETTINGS_VIEWS: readonly SettingsViewId[] = [
   ...SECTIONS.map(s => `config:${s.id}` as SettingsViewId),
   'gateway',
   'keys',
+  'mcp',
   'tools',
   'about'
 ]
 
-export function SettingsView({ onClose, onConfigSaved }: SettingsPageProps) {
+export function SettingsView({ gateway, onClose, onConfigSaved }: SettingsPageProps) {
   const [activeView, setActiveView] = useRouteEnumParam('tab', SETTINGS_VIEWS, 'config:model' as SettingsViewId)
 
   const [queries, setQueries] = useState<Record<SettingsQueryKey, string>>({
@@ -37,6 +39,7 @@ export function SettingsView({ onClose, onConfigSaved }: SettingsPageProps) {
     config: '',
     gateway: '',
     keys: '',
+    mcp: '',
     tools: ''
   })
 
@@ -147,6 +150,12 @@ export function SettingsView({ onClose, onConfigSaved }: SettingsPageProps) {
             label="Skills & Tools"
             onClick={() => setActiveView('tools')}
           />
+          <OverlayNavItem
+            active={activeView === 'mcp'}
+            icon={Wrench}
+            label="MCP"
+            onClick={() => setActiveView('mcp')}
+          />
           <div className="my-2 h-px bg-border/30" />
           <OverlayNavItem
             active={activeView === 'about'}
@@ -196,6 +205,8 @@ export function SettingsView({ onClose, onConfigSaved }: SettingsPageProps) {
             />
           ) : activeView === 'keys' ? (
             <KeysSettings query={queries.keys} />
+          ) : activeView === 'mcp' ? (
+            <McpSettings gateway={gateway} onConfigSaved={onConfigSaved} query={queries.mcp} />
           ) : (
             <ToolsSettings query={queries.tools} />
           )}
diff --git a/apps/desktop/src/app/settings/mcp-settings.tsx b/apps/desktop/src/app/settings/mcp-settings.tsx
new file mode 100644
index 00000000000..428b76bbd64
--- /dev/null
+++ b/apps/desktop/src/app/settings/mcp-settings.tsx
@@ -0,0 +1,259 @@
+import { useEffect, useMemo, useState } from 'react'
+
+import { OverlayActionButton, OverlayCard } from '@/app/overlays/overlay-chrome'
+import { Input } from '@/components/ui/input'
+import { Textarea } from '@/components/ui/textarea'
+import { getHermesConfigRecord, saveHermesConfig, type HermesGateway } from '@/hermes'
+import { Package, Wrench } from '@/lib/icons'
+import { notify, notifyError } from '@/store/notifications'
+import { $activeSessionId } from '@/store/session'
+import { useStore } from '@nanostores/react'
+import type { HermesConfigRecord } from '@/types/hermes'
+
+import { includesQuery } from './helpers'
+import { EmptyState, LoadingState, Pill, SectionHeading, SettingsContent } from './primitives'
+import type { SearchProps } from './types'
+
+interface McpSettingsProps extends SearchProps {
+  gateway?: HermesGateway | null
+  onConfigSaved?: () => void
+}
+
+type McpServers = Record<string, Record<string, unknown>>
+
+const EMPTY_SERVER = {
+  command: '',
+  args: [],
+  env: {}
+}
+
+function getServers(config: HermesConfigRecord | null): McpServers {
+  const raw = config?.mcp_servers
+
+  return raw && typeof raw === 'object' && !Array.isArray(raw) ? (raw as McpServers) : {}
+}
+
+const transportLabel = (server: Record<string, unknown>) =>
+  typeof server.transport === 'string'
+    ? server.transport
+    : typeof server.url === 'string'
+      ? 'http'
+      : typeof server.command === 'string'
+        ? 'stdio'
+        : 'custom'
+
+function serverMatches(name: string, server: Record<string, unknown>, query: string) {
+  if (!query) {
+    return true
+  }
+
+  return includesQuery(name, query) || includesQuery(JSON.stringify(server), query)
+}
+
+export function McpSettings({ gateway, onConfigSaved, query }: McpSettingsProps) {
+  const activeSessionId = useStore($activeSessionId)
+  const [config, setConfig] = useState<HermesConfigRecord | null>(null)
+  const [selected, setSelected] = useState<string | null>(null)
+  const [name, setName] = useState('')
+  const [body, setBody] = useState('')
+  const [saving, setSaving] = useState(false)
+  const [reloading, setReloading] = useState(false)
+
+  useEffect(() => {
+    let cancelled = false
+
+    getHermesConfigRecord()
+      .then(next => {
+        if (cancelled) return
+        setConfig(next)
+        const first = Object.keys(getServers(next)).sort()[0] ?? null
+        setSelected(first)
+      })
+      .catch(err => notifyError(err, 'MCP config failed to load'))
+
+    return () => void (cancelled = true)
+  }, [])
+
+  const servers = useMemo(() => getServers(config), [config])
+  const names = useMemo(() => Object.keys(servers).sort(), [servers])
+  const filtered = useMemo(
+    () => names.filter(serverName => serverMatches(serverName, servers[serverName], query.trim().toLowerCase())),
+    [names, query, servers]
+  )
+
+  useEffect(() => {
+    const server = selected ? servers[selected] : null
+
+    setName(selected ?? '')
+    setBody(JSON.stringify(server ?? EMPTY_SERVER, null, 2))
+  }, [selected, servers])
+
+  if (!config) {
+    return <LoadingState label="Loading MCP servers..." />
+  }
+
+  const saveServer = async () => {
+    const nextName = name.trim()
+
+    if (!nextName) {
+      notify({ kind: 'error', title: 'Name required', message: 'Give this MCP server a config key.' })
+      return
+    }
+
+    let parsed: Record<string, unknown>
+
+    try {
+      const raw = JSON.parse(body)
+
+      if (!raw || typeof raw !== 'object' || Array.isArray(raw)) {
+        throw new Error('Server config must be a JSON object')
+      }
+
+      parsed = raw as Record<string, unknown>
+    } catch (err) {
+      notifyError(err, 'Invalid MCP JSON')
+      return
+    }
+
+    setSaving(true)
+
+    try {
+      const nextServers = { ...servers }
+
+      if (selected && selected !== nextName) {
+        delete nextServers[selected]
+      }
+
+      nextServers[nextName] = parsed
+
+      const nextConfig = { ...config, mcp_servers: nextServers }
+      await saveHermesConfig(nextConfig)
+      setConfig(nextConfig)
+      setSelected(nextName)
+      onConfigSaved?.()
+      notify({ kind: 'success', title: 'MCP server saved', message: `${nextName} applies after MCP reload.` })
+    } catch (err) {
+      notifyError(err, 'Save failed')
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  const removeServer = async (serverName: string) => {
+    setSaving(true)
+
+    try {
+      const nextServers = { ...servers }
+      delete nextServers[serverName]
+
+      const nextConfig = { ...config, mcp_servers: nextServers }
+      await saveHermesConfig(nextConfig)
+      setConfig(nextConfig)
+      setSelected(Object.keys(nextServers).sort()[0] ?? null)
+      onConfigSaved?.()
+    } catch (err) {
+      notifyError(err, 'Remove failed')
+    } finally {
+      setSaving(false)
+    }
+  }
+
+  const reloadMcp = async () => {
+    if (!gateway) {
+      notify({ kind: 'warning', title: 'Gateway unavailable', message: 'Reconnect the gateway before reloading MCP.' })
+      return
+    }
+
+    setReloading(true)
+
+    try {
+      await gateway.request('reload.mcp', {
+        confirm: true,
+        session_id: activeSessionId ?? undefined
+      })
+      notify({ kind: 'success', title: 'MCP tools reloaded', message: 'New tool schemas apply to fresh turns.' })
+    } catch (err) {
+      notifyError(err, 'MCP reload failed')
+    } finally {
+      setReloading(false)
+    }
+  }
+
+  return (
+    <SettingsContent>
+      <div className="mb-4 flex items-center justify-between gap-3">
+        <SectionHeading icon={Package} meta={`${names.length} configured`} title="MCP servers" />
+        <div className="flex items-center gap-2">
+          <OverlayActionButton onClick={() => setSelected(null)}>New server</OverlayActionButton>
+          <OverlayActionButton disabled={reloading} onClick={() => void reloadMcp()}>
+            {reloading ? 'Reloading...' : 'Reload MCP'}
+          </OverlayActionButton>
+        </div>
+      </div>
+
+      <div className="grid min-h-0 gap-4 lg:grid-cols-[17rem_minmax(0,1fr)]">
+        <OverlayCard className="min-h-64 overflow-hidden p-2">
+          {filtered.length === 0 ? (
+            <EmptyState description="Add a stdio or HTTP server to expose MCP tools." title="No MCP servers" />
+          ) : (
+            <div className="grid gap-1">
+              {filtered.map(serverName => {
+                const server = servers[serverName]
+                const active = selected === serverName
+
+                return (
+                  <button
+                    className={`rounded-md px-2 py-2 text-left transition-colors hover:bg-(--chrome-action-hover) ${
+                      active ? 'bg-accent/45 text-foreground' : 'text-muted-foreground'
+                    }`}
+                    key={serverName}
+                    onClick={() => setSelected(serverName)}
+                    type="button"
+                  >
+                    <div className="truncate text-sm font-medium">{serverName}</div>
+                    <div className="mt-1 flex items-center gap-1.5">
+                      <Pill>{transportLabel(server)}</Pill>
+                      {server.disabled === true && <Pill>disabled</Pill>}
+                    </div>
+                  </button>
+                )
+              })}
+            </div>
+          )}
+        </OverlayCard>
+
+        <OverlayCard className="grid gap-3 p-4">
+          <div className="flex items-center gap-2 text-sm font-medium">
+            <Wrench className="size-4 text-muted-foreground" />
+            {selected ? 'Edit server' : 'New server'}
+          </div>
+          <label className="grid gap-1.5">
+            <span className="text-xs text-muted-foreground">Name</span>
+            <Input onChange={event => setName(event.currentTarget.value)} placeholder="filesystem" value={name} />
+          </label>
+          <label className="grid gap-1.5">
+            <span className="text-xs text-muted-foreground">Server JSON</span>
+            <Textarea
+              className="min-h-80 font-mono text-xs"
+              onChange={event => setBody(event.currentTarget.value)}
+              spellCheck={false}
+              value={body}
+            />
+          </label>
+          <div className="flex items-center justify-between">
+            {selected ? (
+              <OverlayActionButton disabled={saving} onClick={() => void removeServer(selected)} tone="danger">
+                Remove
+              </OverlayActionButton>
+            ) : (
+              <span />
+            )}
+            <OverlayActionButton disabled={saving} onClick={() => void saveServer()}>
+              {saving ? 'Saving...' : 'Save server'}
+            </OverlayActionButton>
+          </div>
+        </OverlayCard>
+      </div>
+    </SettingsContent>
+  )
+}
diff --git a/apps/desktop/src/app/settings/types.ts b/apps/desktop/src/app/settings/types.ts
index 7ab8563fd2b..adf97501ddf 100644
--- a/apps/desktop/src/app/settings/types.ts
+++ b/apps/desktop/src/app/settings/types.ts
@@ -1,13 +1,15 @@
 import type { Dispatch, SetStateAction } from 'react'
 
+import type { HermesGateway } from '@/hermes'
 import type { LucideIcon } from '@/lib/icons'
 import type { EnvVarInfo } from '@/types/hermes'
 
-export type SettingsView = 'about' | 'gateway' | 'keys' | 'tools' | `config:${string}`
-export type SettingsQueryKey = 'about' | 'config' | 'gateway' | 'keys' | 'tools'
+export type SettingsView = 'about' | 'gateway' | 'keys' | 'mcp' | 'tools' | `config:${string}`
+export type SettingsQueryKey = 'about' | 'config' | 'gateway' | 'keys' | 'mcp' | 'tools'
 export type EnvPatch = Partial<Pick<EnvVarInfo, 'is_set' | 'redacted_value'>>
 
 export interface SettingsPageProps {
+  gateway?: HermesGateway | null
   onClose: () => void
   onConfigSaved?: () => void
 }
diff --git a/apps/desktop/src/app/shell/hooks/use-statusbar-items.tsx b/apps/desktop/src/app/shell/hooks/use-statusbar-items.tsx
index e598a4dbc49..96ba080ff71 100644
--- a/apps/desktop/src/app/shell/hooks/use-statusbar-items.tsx
+++ b/apps/desktop/src/app/shell/hooks/use-statusbar-items.tsx
@@ -22,6 +22,7 @@ import {
   $workingSessionIds,
   setModelPickerOpen
 } from '@/store/session'
+import { $subagentsBySession, activeSubagentCount } from '@/store/subagents'
 import { $desktopVersion, $updateApply, $updateStatus, setUpdateOverlayOpen } from '@/store/updates'
 import type { StatusResponse } from '@/types/hermes'
 
@@ -63,6 +64,7 @@ export function useStatusbarItems({
   const sessionStartedAt = useStore($sessionStartedAt)
   const turnStartedAt = useStore($turnStartedAt)
   const workingSessionIds = useStore($workingSessionIds)
+  const subagentsBySession = useStore($subagentsBySession)
   const updateStatus = useStore($updateStatus)
   const updateApply = useStore($updateApply)
   const desktopVersion = useStore($desktopVersion)
@@ -106,15 +108,20 @@ export function useStatusbarItems({
     [gatewayLogLines, handleRestartGateway, openCommandCenterSection, restartingGateway, statusSnapshot]
   )
 
-  const { bgFailed, bgRunning } = useMemo(() => {
+  const { bgFailed, bgRunning, subagentsRunning } = useMemo(() => {
     const actions = Object.values(desktopActionTasks)
     const running = actions.filter(t => t.status.running).length
     const failed = actions.filter(t => !t.status.running && (t.status.exit_code ?? 0) !== 0).length
     const previewRunning = previewServerRestartStatus === 'running' ? 1 : 0
     const previewFailed = previewServerRestartStatus === 'error' ? 1 : 0
+    const subagentsRunning = Object.values(subagentsBySession).reduce((sum, items) => sum + activeSubagentCount(items), 0)
 
-    return { bgFailed: failed + previewFailed, bgRunning: workingSessionIds.length + running + previewRunning }
-  }, [desktopActionTasks, previewServerRestartStatus, workingSessionIds])
+    return {
+      bgFailed: failed + previewFailed,
+      bgRunning: workingSessionIds.length + running + previewRunning,
+      subagentsRunning
+    }
+  }, [desktopActionTasks, previewServerRestartStatus, subagentsBySession, workingSessionIds])
 
   const gatewayUp = Boolean(statusSnapshot?.gateway_running)
 
@@ -189,11 +196,18 @@ export function useStatusbarItems({
           agentsOpen && 'bg-accent/55 text-foreground',
           bgFailed > 0 && 'text-destructive hover:text-destructive'
         ),
-        detail: bgFailed > 0 ? `${bgFailed} failed` : bgRunning > 0 ? `${bgRunning} running` : undefined,
+        detail:
+          subagentsRunning > 0
+            ? `${subagentsRunning} subagent${subagentsRunning === 1 ? '' : 's'}`
+            : bgFailed > 0
+              ? `${bgFailed} failed`
+              : bgRunning > 0
+                ? `${bgRunning} running`
+                : undefined,
         icon:
           bgFailed > 0 ? (
             <AlertCircle className="size-3" />
-          ) : bgRunning > 0 ? (
+          ) : bgRunning > 0 || subagentsRunning > 0 ? (
             <Loader2 className="size-3 animate-spin" />
           ) : (
             <Sparkles className="size-3" />
@@ -214,6 +228,7 @@ export function useStatusbarItems({
       gatewayUp,
       openAgents,
       statusSnapshot?.gateway_state,
+      subagentsRunning,
       toggleCommandCenter
     ]
   )
diff --git a/apps/desktop/src/store/subagents.test.ts b/apps/desktop/src/store/subagents.test.ts
new file mode 100644
index 00000000000..57e3390147c
--- /dev/null
+++ b/apps/desktop/src/store/subagents.test.ts
@@ -0,0 +1,63 @@
+import { beforeEach, describe, expect, it } from 'vitest'
+
+import { $subagentsBySession, activeSubagentCount, buildSubagentTree, clearSessionSubagents, upsertSubagent } from './subagents'
+
+describe('subagent store', () => {
+  beforeEach(() => {
+    $subagentsBySession.set({})
+  })
+
+  it('upserts subagent progress and keeps terminal status stable', () => {
+    upsertSubagent('s1', {
+      goal: 'scan files',
+      status: 'running',
+      subagent_id: 'a1',
+      task_index: 0
+    })
+    upsertSubagent('s1', {
+      goal: 'scan files',
+      status: 'completed',
+      subagent_id: 'a1',
+      summary: 'done',
+      task_index: 0
+    })
+    upsertSubagent('s1', {
+      goal: 'scan files',
+      status: 'running',
+      subagent_id: 'a1',
+      task_index: 0,
+      text: 'late'
+    })
+
+    const item = $subagentsBySession.get().s1?.[0]
+    expect(item?.status).toBe('completed')
+    expect(item?.summary).toBe('done')
+  })
+
+  it('builds parent/child trees', () => {
+    upsertSubagent('s1', { goal: 'parent', status: 'running', subagent_id: 'p', task_index: 0 })
+    upsertSubagent('s1', {
+      goal: 'child',
+      parent_id: 'p',
+      status: 'queued',
+      subagent_id: 'c',
+      task_index: 1
+    })
+
+    const tree = buildSubagentTree($subagentsBySession.get().s1 ?? [])
+
+    expect(tree).toHaveLength(1)
+    expect(tree[0]?.children[0]?.goal).toBe('child')
+    expect(activeSubagentCount($subagentsBySession.get().s1 ?? [])).toBe(2)
+  })
+
+  it('clears one session without touching another', () => {
+    upsertSubagent('s1', { goal: 'one', status: 'running', subagent_id: 'a1', task_index: 0 })
+    upsertSubagent('s2', { goal: 'two', status: 'running', subagent_id: 'a2', task_index: 0 })
+
+    clearSessionSubagents('s1')
+
+    expect($subagentsBySession.get().s1).toBeUndefined()
+    expect($subagentsBySession.get().s2).toHaveLength(1)
+  })
+})
diff --git a/apps/desktop/src/store/subagents.ts b/apps/desktop/src/store/subagents.ts
new file mode 100644
index 00000000000..a9b6a6d6788
--- /dev/null
+++ b/apps/desktop/src/store/subagents.ts
@@ -0,0 +1,159 @@
+import { atom } from 'nanostores'
+
+export type SubagentStatus = 'completed' | 'failed' | 'interrupted' | 'queued' | 'running'
+
+export interface SubagentProgress {
+  id: string
+  apiCalls?: number
+  costUsd?: number
+  depth: number
+  durationSeconds?: number
+  filesRead: string[]
+  filesWritten: string[]
+  goal: string
+  inputTokens?: number
+  model?: string
+  outputTail: { isError?: boolean; preview?: string; tool?: string }[]
+  outputTokens?: number
+  parentId: null | string
+  reasoningTokens?: number
+  sessionId: string
+  status: SubagentStatus
+  summary?: string
+  taskCount: number
+  taskIndex: number
+  toolName?: string
+  toolPreview?: string
+  toolsets: string[]
+  updatedAt: number
+}
+
+export interface SubagentNode extends SubagentProgress {
+  children: SubagentNode[]
+}
+
+export type SubagentPayload = Record<string, unknown>
+
+export const $subagentsBySession = atom<Record<string, SubagentProgress[]>>({})
+
+const TERMINAL = new Set<SubagentStatus>(['completed', 'failed', 'interrupted'])
+
+const asString = (value: unknown) => (typeof value === 'string' ? value : '')
+const asNumber = (value: unknown) => (typeof value === 'number' && Number.isFinite(value) ? value : undefined)
+const asStatus = (value: unknown): SubagentStatus =>
+  value === 'completed' || value === 'failed' || value === 'interrupted' || value === 'queued' ? value : 'running'
+
+const asStringList = (value: unknown) => (Array.isArray(value) ? value.map(asString).filter(Boolean) : [])
+
+const asOutputTail = (value: unknown): SubagentProgress['outputTail'] =>
+  Array.isArray(value)
+    ? value
+        .map(item => (item && typeof item === 'object' ? (item as Record<string, unknown>) : null))
+        .filter((item): item is Record<string, unknown> => Boolean(item))
+        .map(item => ({
+          isError: item.is_error === true,
+          preview: asString(item.preview) || undefined,
+          tool: asString(item.tool) || undefined
+        }))
+    : []
+
+function idFor(payload: SubagentPayload) {
+  return (
+    asString(payload.subagent_id) ||
+    `${asString(payload.parent_id) || 'root'}:${asNumber(payload.task_index) ?? 0}:${asString(payload.goal)}`
+  )
+}
+
+function toProgress(sessionId: string, payload: SubagentPayload, previous?: SubagentProgress): SubagentProgress {
+  return {
+    apiCalls: asNumber(payload.api_calls) ?? previous?.apiCalls,
+    costUsd: asNumber(payload.cost_usd) ?? previous?.costUsd,
+    depth: asNumber(payload.depth) ?? previous?.depth ?? 0,
+    durationSeconds: asNumber(payload.duration_seconds) ?? previous?.durationSeconds,
+    filesRead: asStringList(payload.files_read).length ? asStringList(payload.files_read) : (previous?.filesRead ?? []),
+    filesWritten: asStringList(payload.files_written).length
+      ? asStringList(payload.files_written)
+      : (previous?.filesWritten ?? []),
+    goal: asString(payload.goal) || previous?.goal || 'Subagent',
+    id: previous?.id || idFor(payload),
+    inputTokens: asNumber(payload.input_tokens) ?? previous?.inputTokens,
+    model: asString(payload.model) || previous?.model,
+    outputTail: asOutputTail(payload.output_tail).length ? asOutputTail(payload.output_tail) : (previous?.outputTail ?? []),
+    outputTokens: asNumber(payload.output_tokens) ?? previous?.outputTokens,
+    parentId: asString(payload.parent_id) || previous?.parentId || null,
+    reasoningTokens: asNumber(payload.reasoning_tokens) ?? previous?.reasoningTokens,
+    sessionId,
+    status: asStatus(payload.status),
+    summary: asString(payload.summary) || previous?.summary,
+    taskCount: asNumber(payload.task_count) ?? previous?.taskCount ?? 1,
+    taskIndex: asNumber(payload.task_index) ?? previous?.taskIndex ?? 0,
+    toolName: asString(payload.tool_name) || previous?.toolName,
+    toolPreview: asString(payload.tool_preview) || asString(payload.text) || previous?.toolPreview,
+    toolsets: asStringList(payload.toolsets).length ? asStringList(payload.toolsets) : (previous?.toolsets ?? []),
+    updatedAt: Date.now()
+  }
+}
+
+export function clearSessionSubagents(sessionId: string) {
+  const current = $subagentsBySession.get()
+
+  if (!(sessionId in current)) {
+    return
+  }
+
+  const next = { ...current }
+  delete next[sessionId]
+  $subagentsBySession.set(next)
+}
+
+export function upsertSubagent(sessionId: string, payload: SubagentPayload, createIfMissing = true) {
+  const current = $subagentsBySession.get()
+  const list = current[sessionId] ?? []
+  const id = idFor(payload)
+  const index = list.findIndex(item => item.id === id)
+
+  if (index < 0 && !createIfMissing) {
+    return
+  }
+
+  const previous = index >= 0 ? list[index] : undefined
+
+  if (previous && TERMINAL.has(previous.status)) {
+    return
+  }
+
+  const nextItem = toProgress(sessionId, payload, previous)
+  const nextList = index >= 0 ? list.map(item => (item.id === id ? nextItem : item)) : [...list, nextItem]
+
+  $subagentsBySession.set({ ...current, [sessionId]: nextList })
+}
+
+export function buildSubagentTree(items: readonly SubagentProgress[]): SubagentNode[] {
+  const nodes = new Map<string, SubagentNode>()
+
+  for (const item of items) {
+    nodes.set(item.id, { ...item, children: [] })
+  }
+
+  const roots: SubagentNode[] = []
+
+  for (const node of nodes.values()) {
+    const parent = node.parentId ? nodes.get(node.parentId) : null
+
+    if (parent) {
+      parent.children.push(node)
+    } else {
+      roots.push(node)
+    }
+  }
+
+  const sort = (a: SubagentNode, b: SubagentNode) => a.taskIndex - b.taskIndex || a.goal.localeCompare(b.goal)
+  const walk = (node: SubagentNode) => node.children.sort(sort).forEach(walk)
+
+  roots.sort(sort).forEach(walk)
+
+  return roots
+}
+
+export const activeSubagentCount = (items: readonly SubagentProgress[]) =>
+  items.filter(item => item.status === 'queued' || item.status === 'running').length