diff --git a/desktop/src/components/activity/SessionActivityPanel.test.tsx b/desktop/src/components/activity/SessionActivityPanel.test.tsx
index 387b318d..83cb2eed 100644
--- a/desktop/src/components/activity/SessionActivityPanel.test.tsx
+++ b/desktop/src/components/activity/SessionActivityPanel.test.tsx
@@ -101,10 +101,15 @@ function model(overrides: Partial<SessionActivityModel> = {}): SessionActivityMo
 describe('SessionActivityPanel', () => {
   afterEach(cleanup)
 
-  it('renders sections, rows, and empty states', () => {
+  it('renders populated tasks section without empty visible section labels', () => {
     render(
       <SessionActivityPanel
-        model={model()}
+        model={model({
+          sections: {
+            ...model().sections,
+            subagents: { id: 'subagents', title: 'SubAgents', emptyLabel: 'No SubAgents', rows: [] },
+          },
+        })}
         open
         onClose={vi.fn()}
         onOpenSubagent={vi.fn()}
@@ -118,15 +123,14 @@ describe('SessionActivityPanel', () => {
     expect(screen.getByText('Add panel coverage')).toHaveAttribute('title', 'Add panel coverage')
     expect(screen.getByLabelText('Task in progress')).toBeInTheDocument()
     expect(screen.queryByText('In progress')).not.toBeInTheDocument()
-    expect(screen.getByText('Team')).toBeInTheDocument()
-    expect(screen.getByText('No team members')).toBeInTheDocument()
-    expect(screen.getByText('Background Tasks')).toBeInTheDocument()
-    expect(screen.getByText('SubAgents')).toBeInTheDocument()
-    expect(screen.getByText('Kuhn')).toBeInTheDocument()
-    expect(screen.getByText('Running')).toBeInTheDocument()
-    expect(screen.getByText('Sources')).toBeInTheDocument()
-    expect(screen.getByText('No background tasks')).toBeInTheDocument()
-    expect(screen.getByText('No sources')).toBeInTheDocument()
+    expect(screen.queryByText('Team')).not.toBeInTheDocument()
+    expect(screen.queryByText('Background Tasks')).not.toBeInTheDocument()
+    expect(screen.queryByText('SubAgents')).not.toBeInTheDocument()
+    expect(screen.queryByText('Sources')).not.toBeInTheDocument()
+    expect(screen.queryByText('No team members')).not.toBeInTheDocument()
+    expect(screen.queryByText('No background tasks')).not.toBeInTheDocument()
+    expect(screen.queryByText('No SubAgents')).not.toBeInTheDocument()
+    expect(screen.queryByText('No sources')).not.toBeInTheDocument()
   })
 
   it('renders task rows as checklist markers instead of status chips', () => {
@@ -386,11 +390,12 @@ describe('SessionActivityPanel', () => {
     )
 
     expect(screen.getByTestId('session-activity-panel')).toHaveAttribute('data-placement', 'rail')
-    expect(screen.getByTestId('session-activity-panel')).toHaveClass('my-3')
-    expect(screen.getByTestId('session-activity-panel')).toHaveClass('mr-3')
-    expect(screen.getByTestId('session-activity-panel')).toHaveClass('rounded-xl')
+    expect(screen.getByTestId('session-activity-panel')).toHaveClass('my-4')
+    expect(screen.getByTestId('session-activity-panel')).toHaveClass('mr-4')
+    expect(screen.getByTestId('session-activity-panel')).toHaveClass('w-[340px]')
+    expect(screen.getByTestId('session-activity-panel')).toHaveClass('rounded-[24px]')
     expect(screen.getByTestId('session-activity-panel')).toHaveClass('self-start')
-    expect(screen.getByTestId('session-activity-panel')).toHaveClass('max-h-[min(480px,calc(100vh-88px))]')
+    expect(screen.getByTestId('session-activity-panel')).toHaveClass('max-h-[min(480px,calc(100vh-96px))]')
     expect(screen.getByTestId('session-activity-panel')).not.toHaveClass('h-[calc(100%-24px)]')
     fireEvent.pointerDown(screen.getByRole('button', { name: 'Outside' }))
 
@@ -455,10 +460,10 @@ describe('SessionActivityPanel', () => {
     const backgroundSection = document.querySelector('section[aria-label="Background Tasks"]')
     const subagentsSection = document.querySelector('section[aria-label="SubAgents"]')
 
-    expect(tasksSection?.querySelector('.max-h-40.overflow-y-auto')).toBeInTheDocument()
-    expect(teamSection?.querySelector('.max-h-32.overflow-y-auto')).toBeInTheDocument()
-    expect(backgroundSection?.querySelector('.max-h-36.overflow-y-auto')).toBeInTheDocument()
-    expect(subagentsSection?.querySelector('.max-h-36.overflow-y-auto')).toBeInTheDocument()
+    expect(tasksSection?.querySelector('.max-h-44.overflow-y-auto')).toBeInTheDocument()
+    expect(teamSection?.querySelector('.max-h-36.overflow-y-auto')).toBeInTheDocument()
+    expect(backgroundSection?.querySelector('.max-h-40.overflow-y-auto')).toBeInTheDocument()
+    expect(subagentsSection?.querySelector('.max-h-40.overflow-y-auto')).toBeInTheDocument()
   })
 
   it('opens a SubAgent row when the row is openable', () => {
diff --git a/desktop/src/components/activity/SessionActivityPanel.tsx b/desktop/src/components/activity/SessionActivityPanel.tsx
index 48686787..4e761c02 100644
--- a/desktop/src/components/activity/SessionActivityPanel.tsx
+++ b/desktop/src/components/activity/SessionActivityPanel.tsx
@@ -1,6 +1,6 @@
 import { useEffect, useMemo, useRef, useState } from 'react'
-import { Check, LoaderCircle, X } from 'lucide-react'
-import type { ActivityRow, ActivitySectionId, SessionActivityModel } from './sessionActivityModel'
+import { Bot, Check, ChevronRight, Circle, FileText, LoaderCircle, Terminal, Users, X } from 'lucide-react'
+import { getVisibleActivitySections, type ActivityRow, type ActivitySectionId, type SessionActivityModel } from './sessionActivityModel'
 import { useTranslation } from '../../i18n'
 import type { BackgroundAgentTask } from '../../types/chat'
 import type { TeamMember } from '../../types/team'
@@ -14,8 +14,6 @@ export type OpenSubagentPayload = {
 
 type SessionActivityPanelPlacement = 'overlay' | 'rail'
 
-const SECTION_ORDER = ['tasks', 'team', 'backgroundTasks', 'subagents', 'sources'] as const
-
 type TranslationFn = ReturnType<typeof useTranslation>
 
 function fallbackStatusLabel(status: ActivityRow['status']): string {
@@ -64,40 +62,23 @@ function getSectionTitle(sectionId: ActivitySectionId, t: TranslationFn): string
   }
 }
 
-function getSectionEmptyLabel(sectionId: ActivitySectionId, t: TranslationFn): string {
-  switch (sectionId) {
-    case 'tasks':
-      return t('session.activity.empty.tasks')
-    case 'team':
-      return t('session.activity.empty.team')
-    case 'backgroundTasks':
-      return t('session.activity.empty.backgroundTasks')
-    case 'subagents':
-      return t('session.activity.empty.subagents')
-    case 'sources':
-      return t('session.activity.empty.sources')
-    case 'output':
-      return ''
-  }
-}
-
 function getSectionRowsClassName(sectionId: ActivitySectionId, rowCount: number): string {
-  const base = 'space-y-0.5'
+  const base = 'space-y-1'
   if (rowCount === 0) return base
 
   switch (sectionId) {
     case 'tasks':
-      return `${base} max-h-40 overflow-y-auto overscroll-contain pr-1`
+      return `${base} max-h-44 overflow-y-auto overscroll-contain pr-1`
     case 'team':
-      return `${base} max-h-32 overflow-y-auto overscroll-contain pr-1`
+      return `${base} max-h-36 overflow-y-auto overscroll-contain pr-1`
     case 'backgroundTasks':
-      return `${base} max-h-36 overflow-y-auto overscroll-contain pr-1`
+      return `${base} max-h-40 overflow-y-auto overscroll-contain pr-1`
     case 'subagents':
-      return `${base} max-h-36 overflow-y-auto overscroll-contain pr-1`
+      return `${base} max-h-40 overflow-y-auto overscroll-contain pr-1`
     case 'sources':
-      return `${base} max-h-24 overflow-y-auto overscroll-contain pr-1`
+      return `${base} max-h-28 overflow-y-auto overscroll-contain pr-1`
     case 'output':
-      return `${base} max-h-24 overflow-y-auto overscroll-contain pr-1`
+      return `${base} max-h-28 overflow-y-auto overscroll-contain pr-1`
   }
 }
 
@@ -156,9 +137,9 @@ function TaskStatusMarker({ status, t }: { status: ActivityRow['status']; t: Tra
     return (
       <span
         aria-label={t('session.activity.task.completed')}
-        className="inline-flex h-4 w-4 shrink-0 items-center justify-center rounded border border-[var(--color-success)] bg-[var(--color-success)] text-white"
+        className="inline-flex h-5 w-5 shrink-0 items-center justify-center rounded-md border border-[var(--color-success)] bg-[var(--color-success)] text-white shadow-[inset_0_1px_0_rgba(255,255,255,0.24)]"
       >
-        <Check size={12} strokeWidth={3} aria-hidden="true" />
+        <Check size={13} strokeWidth={3} aria-hidden="true" />
       </span>
     )
   }
@@ -167,9 +148,9 @@ function TaskStatusMarker({ status, t }: { status: ActivityRow['status']; t: Tra
     return (
       <span
         aria-label={t('session.activity.task.inProgress')}
-        className="inline-flex h-4 w-4 shrink-0 items-center justify-center rounded border border-[var(--color-accent)] text-[var(--color-accent)]"
+        className="inline-flex h-5 w-5 shrink-0 items-center justify-center rounded-md border border-[var(--color-accent)] bg-[var(--color-surface)] text-[var(--color-accent)]"
       >
-        <LoaderCircle size={12} strokeWidth={2.4} aria-hidden="true" className="animate-spin" />
+        <LoaderCircle size={13} strokeWidth={2.4} aria-hidden="true" className="animate-spin" />
       </span>
     )
   }
@@ -177,11 +158,40 @@ function TaskStatusMarker({ status, t }: { status: ActivityRow['status']; t: Tra
   return (
     <span
       aria-label={t('session.activity.task.pending')}
-      className="inline-flex h-4 w-4 shrink-0 rounded border border-[var(--color-border)] bg-[var(--color-surface)]"
+      className="inline-flex h-5 w-5 shrink-0 rounded-md border border-[var(--color-border)] bg-[var(--color-surface)]"
     />
   )
 }
 
+function getRowIcon(row: ActivityRow) {
+  switch (row.section) {
+    case 'team':
+      return Users
+    case 'backgroundTasks':
+      return Terminal
+    case 'subagents':
+      return Bot
+    case 'sources':
+    case 'output':
+      return FileText
+    case 'tasks':
+      return Circle
+  }
+}
+
+function getStatusTone(status: ActivityRow['status']) {
+  if (status === 'running' || status === 'in_progress') {
+    return 'bg-[var(--color-accent)]'
+  }
+  if (status === 'completed' || status === 'idle') {
+    return 'bg-[var(--color-success)]'
+  }
+  if (status === 'failed' || status === 'error' || status === 'stopped') {
+    return 'bg-[var(--color-error)]'
+  }
+  return 'bg-[var(--color-text-tertiary)]'
+}
+
 function ActivityRowView({
   row,
   sessionId,
@@ -215,17 +225,26 @@ function ActivityRowView({
         : undefined
   const content = (
     <>
-      {isTask ? <TaskStatusMarker status={row.status} t={t} /> : null}
+      {isTask ? (
+        <TaskStatusMarker status={row.status} t={t} />
+      ) : (
+        <span className="inline-flex h-6 w-6 shrink-0 items-center justify-center rounded-lg text-[var(--color-text-tertiary)]">
+          {(() => {
+            const Icon = getRowIcon(row)
+            return <Icon size={17} strokeWidth={2} aria-hidden="true" />
+          })()}
+        </span>
+      )}
       <span className="min-w-0 flex-1 truncate text-left">
         <span
-          className={`block truncate text-xs font-medium ${isTask && row.status === 'completed' ? 'text-[var(--color-text-tertiary)] line-through' : 'text-[var(--color-text-primary)]'}`}
+          className={`block truncate text-[13px] font-semibold leading-5 ${isTask && row.status === 'completed' ? 'text-[var(--color-text-tertiary)] line-through decoration-[var(--color-text-tertiary)]/60' : 'text-[var(--color-text-primary)]'}`}
           title={label}
         >
           {label}
         </span>
         {detail ? (
           <span
-            className="block truncate text-[11px] text-[var(--color-text-tertiary)]"
+            className="block truncate text-[11px] leading-4 text-[var(--color-text-tertiary)]"
             title={detail}
           >
             {detail}
@@ -233,12 +252,18 @@ function ActivityRowView({
         ) : null}
       </span>
       {isTask ? null : (
-        <span className="shrink-0 rounded bg-[var(--color-surface-container)] px-1.5 py-0.5 text-[10px] text-[var(--color-text-tertiary)]">
+        <span className="inline-flex shrink-0 items-center gap-1.5 text-[11px] font-medium text-[var(--color-text-tertiary)]">
+          <span className={`h-1.5 w-1.5 rounded-full ${getStatusTone(row.status)}`} aria-hidden="true" />
           {getActivityStatusLabel(row.status, t)}
         </span>
       )}
+      {!isTask && row.openable ? (
+        <ChevronRight size={14} strokeWidth={2.2} className="shrink-0 text-[var(--color-text-tertiary)]" aria-hidden="true" />
+      ) : null}
     </>
   )
+  const interactiveRowClassName =
+    'flex w-full items-center gap-2.5 rounded-xl px-3 py-2.5 text-left transition-[background-color,transform] duration-150 ease-out hover:bg-[var(--color-surface-hover)] active:translate-y-px focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)]'
 
   if (row.section === 'team' && row.member && onOpenMember) {
     return (
@@ -246,7 +271,7 @@ function ActivityRowView({
         type="button"
         aria-label={t('session.activity.openTeamMember', { name: row.label })}
         onClick={() => onOpenMember(row.member!)}
-        className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left transition-colors hover:bg-[var(--color-surface-hover)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)]"
+        className={interactiveRowClassName}
       >
         {content}
       </button>
@@ -259,7 +284,7 @@ function ActivityRowView({
         type="button"
         aria-label={t('session.activity.openRun', { name: row.label })}
         onClick={() => onOpenSubagent({ sessionId, toolUseId: row.toolUseId!, title: row.label })}
-        className="flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left transition-colors hover:bg-[var(--color-surface-hover)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)]"
+        className={interactiveRowClassName}
       >
         {content}
       </button>
@@ -273,7 +298,7 @@ function ActivityRowView({
         aria-label={t('session.activity.openBackgroundTask', { name: row.label })}
         aria-expanded={selected}
         onClick={() => onOpenBackgroundTask(row)}
-        className={`flex w-full items-center gap-2 rounded-md px-2 py-1.5 text-left transition-colors hover:bg-[var(--color-surface-hover)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)] ${selected ? 'bg-[var(--color-surface-container)]' : ''}`}
+        className={`${interactiveRowClassName} ${selected ? 'bg-[var(--color-surface-container)]' : ''}`}
       >
         {content}
       </button>
@@ -281,7 +306,7 @@ function ActivityRowView({
   }
 
   return (
-    <div className="flex items-center gap-2 rounded-md px-2 py-1.5">
+    <div className="flex items-center gap-2.5 rounded-xl px-3 py-2.5">
       {content}
     </div>
   )
@@ -317,14 +342,14 @@ function BackgroundTaskDetail({ row }: { row: ActivityRow }) {
   if (details.length === 0) return null
 
   return (
-    <div className="mx-2 mb-1 rounded-md border border-[var(--color-border)] bg-[var(--color-surface-container-low)] p-2">
-      <div className="mb-1 text-[11px] font-semibold text-[var(--color-text-tertiary)]">
+    <div className="mx-3 mb-1.5 rounded-2xl border border-[var(--color-border)] bg-[var(--color-surface-container-low)] p-3 shadow-[inset_0_1px_0_rgba(255,255,255,0.54)]">
+      <div className="mb-2 text-[11px] font-semibold text-[var(--color-text-tertiary)]">
         {t('session.activity.details.title')}
       </div>
-      <dl className="space-y-1.5">
+      <dl className="space-y-2">
         {details.map((detail) => (
           <div key={detail.label} className="min-w-0">
-            <dt className="text-[10px] font-semibold uppercase tracking-normal text-[var(--color-text-tertiary)]">
+            <dt className="text-[10px] font-semibold text-[var(--color-text-tertiary)]">
               {detail.label}
             </dt>
             <dd className="max-h-28 overflow-auto whitespace-pre-wrap break-words text-[11px] leading-relaxed text-[var(--color-text-secondary)]">
@@ -358,6 +383,7 @@ export function SessionActivityPanel({
   const panelRef = useRef<HTMLDivElement>(null)
   const [selectedBackgroundTaskId, setSelectedBackgroundTaskId] = useState<string | null>(null)
   const finishedBackgroundTaskKeys = useMemo(() => getFinishedBackgroundTaskKeys(model), [model])
+  const visibleSections = useMemo(() => getVisibleActivitySections(model), [model])
 
   useEffect(() => {
     if (!open) return
@@ -401,8 +427,8 @@ export function SessionActivityPanel({
 
   if (!open) return null
   const className = placement === 'rail'
-    ? 'my-3 ml-2 mr-3 flex max-h-[min(480px,calc(100vh-88px))] w-[300px] shrink-0 self-start flex-col overflow-hidden rounded-xl border border-[var(--color-border)] bg-[var(--color-surface)] shadow-[0_18px_48px_-30px_rgba(15,23,42,0.42),0_8px_20px_-18px_rgba(15,23,42,0.28),inset_0_1px_0_rgba(255,255,255,0.72)]'
-    : 'absolute right-3 top-3 z-40 flex max-h-[calc(100%-96px)] w-[min(300px,calc(100%-24px))] flex-col overflow-hidden rounded-lg border border-[var(--color-border)] bg-[var(--color-surface)] shadow-[var(--shadow-dropdown)]'
+    ? 'my-4 ml-3 mr-4 flex max-h-[min(480px,calc(100vh-96px))] w-[340px] shrink-0 self-start flex-col overflow-hidden rounded-[24px] border border-[var(--color-border)] bg-[var(--color-surface)] shadow-[0_26px_80px_-48px_rgba(15,23,42,0.58),0_12px_30px_-22px_rgba(15,23,42,0.34),inset_0_1px_0_rgba(255,255,255,0.82)]'
+    : 'absolute right-4 top-4 z-40 flex max-h-[calc(100%-112px)] w-[min(340px,calc(100%-32px))] flex-col overflow-hidden rounded-[24px] border border-[var(--color-border)] bg-[var(--color-surface)] shadow-[0_26px_80px_-48px_rgba(15,23,42,0.58),0_12px_30px_-22px_rgba(15,23,42,0.34),inset_0_1px_0_rgba(255,255,255,0.82)]'
 
   return (
     <div
@@ -413,33 +439,35 @@ export function SessionActivityPanel({
       data-placement={placement}
       className={className}
     >
-      <div className="flex items-center justify-between border-b border-[var(--color-border)] px-3 py-2">
-        <h2 className="text-xs font-semibold text-[var(--color-text-primary)]">{t('session.activity.title')}</h2>
+      <div className="flex items-center justify-between px-5 pb-2 pt-4">
+        <h2 className="text-[13px] font-semibold text-[var(--color-text-secondary)]">{t('session.activity.title')}</h2>
         <button
           type="button"
           aria-label={t('session.activity.close')}
           onClick={onClose}
-          className="inline-flex h-7 w-7 items-center justify-center rounded-md text-[var(--color-text-tertiary)] transition-colors hover:bg-[var(--color-surface-hover)] hover:text-[var(--color-text-primary)] focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)]"
+          className="inline-flex h-8 w-8 items-center justify-center rounded-xl text-[var(--color-text-tertiary)] transition-[background-color,color,transform] duration-150 ease-out hover:bg-[var(--color-surface-hover)] hover:text-[var(--color-text-primary)] active:translate-y-px focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-[var(--color-border-focus)]"
         >
-          <X size={14} strokeWidth={2.2} aria-hidden="true" />
+          <X size={15} strokeWidth={2.2} aria-hidden="true" />
         </button>
       </div>
 
-      <div className="min-h-0 flex-1 space-y-3 overflow-y-auto p-3">
-        {SECTION_ORDER.map((sectionId) => {
-          const section = model.sections[sectionId]
+      <div className="min-h-0 flex-1 space-y-4 overflow-y-auto px-5 pb-5 pt-1">
+        {visibleSections.map((section, index) => {
           const sectionTitle = getSectionTitle(section.id, t)
-          const sectionEmptyLabel = getSectionEmptyLabel(section.id, t)
 
           return (
-            <section key={section.id} aria-label={sectionTitle}>
-              <div className="mb-1 flex items-center justify-between gap-2 px-1">
-                <div className="flex min-w-0 items-center gap-1.5">
-                  <h3 className="text-[11px] font-semibold uppercase tracking-normal text-[var(--color-text-tertiary)]">
+            <section
+              key={section.id}
+              aria-label={sectionTitle}
+              className={index > 0 ? 'border-t border-[var(--color-border)] pt-4' : undefined}
+            >
+              <div className="mb-2 flex items-center justify-between gap-2 px-1">
+                <div className="flex min-w-0 items-center gap-2">
+                  <h3 className="text-[12px] font-semibold text-[var(--color-text-tertiary)]">
                     {sectionTitle}
                   </h3>
                   {section.rows.length > 0 ? (
-                    <span className="rounded bg-[var(--color-surface-container)] px-1.5 py-0.5 text-[10px] leading-none text-[var(--color-text-tertiary)]">
+                    <span className="rounded-full bg-[var(--color-surface-container)] px-2 py-0.5 text-[10px] leading-none text-[var(--color-text-tertiary)]">
                       {section.rows.length}
                     </span>
                   ) : null}
@@ -454,31 +482,27 @@ export function SessionActivityPanel({
                   </button>
                 ) : null}
               </div>
-              {section.rows.length === 0 ? (
-                <div className="px-2 py-1 text-xs text-[var(--color-text-tertiary)]">{sectionEmptyLabel}</div>
-              ) : (
-                <div className={getSectionRowsClassName(section.id, section.rows.length)}>
-                  {section.rows.map((row) => (
-                    <div key={row.id}>
-                      <ActivityRowView
-                        row={row}
-                        sessionId={model.sessionId}
-                        onOpenSubagent={onOpenSubagent}
-                        onOpenMember={onOpenMember}
-                        onOpenBackgroundTask={(backgroundRow) => {
-                          setSelectedBackgroundTaskId((current) => (
-                            current === backgroundRow.id ? null : backgroundRow.id
-                          ))
-                        }}
-                        selected={section.id === 'backgroundTasks' && selectedBackgroundTaskId === row.id}
-                      />
-                      {section.id === 'backgroundTasks' && selectedBackgroundTaskId === row.id ? (
-                        <BackgroundTaskDetail row={row} />
-                      ) : null}
-                    </div>
-                  ))}
-                </div>
-              )}
+              <div className={getSectionRowsClassName(section.id, section.rows.length)}>
+                {section.rows.map((row) => (
+                  <div key={row.id}>
+                    <ActivityRowView
+                      row={row}
+                      sessionId={model.sessionId}
+                      onOpenSubagent={onOpenSubagent}
+                      onOpenMember={onOpenMember}
+                      onOpenBackgroundTask={(backgroundRow) => {
+                        setSelectedBackgroundTaskId((current) => (
+                          current === backgroundRow.id ? null : backgroundRow.id
+                        ))
+                      }}
+                      selected={section.id === 'backgroundTasks' && selectedBackgroundTaskId === row.id}
+                    />
+                    {section.id === 'backgroundTasks' && selectedBackgroundTaskId === row.id ? (
+                      <BackgroundTaskDetail row={row} />
+                    ) : null}
+                  </div>
+                ))}
+              </div>
             </section>
           )
         })}
diff --git a/desktop/src/components/activity/sessionActivityModel.test.ts b/desktop/src/components/activity/sessionActivityModel.test.ts
index 873450be..87ae406b 100644
--- a/desktop/src/components/activity/sessionActivityModel.test.ts
+++ b/desktop/src/components/activity/sessionActivityModel.test.ts
@@ -1,5 +1,9 @@
 import { describe, expect, it } from 'vitest'
-import { buildSessionActivityModel } from './sessionActivityModel'
+import {
+  buildSessionActivityModel,
+  getVisibleActivitySections,
+  hasVisibleSessionActivity,
+} from './sessionActivityModel'
 import { createBackgroundTaskDismissKey } from '../../lib/backgroundTasks'
 import type { BackgroundAgentTask, AgentTaskNotification, UIMessage } from '../../types/chat'
 import type { CLITask } from '../../types/cliTask'
@@ -77,6 +81,167 @@ const agentMessages: UIMessage[] = [
 ]
 
 describe('buildSessionActivityModel', () => {
+  it('reports no visible activity for an empty model', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [],
+      agentNotifications: [],
+    })
+
+    expect(hasVisibleSessionActivity(model)).toBe(false)
+    expect(getVisibleActivitySections(model)).toEqual([])
+    expect(model.badgeCount).toBe(0)
+  })
+
+  it('keeps completed TodoWrite historical tasks visible without badge attention', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      messages: [{
+        id: 'todo-1',
+        type: 'tool_use',
+        toolName: 'TodoWrite',
+        toolUseId: 'todo-1',
+        input: {
+          todos: [
+            { content: '审查现有实现', status: 'completed' },
+          ],
+        },
+        timestamp: 1000,
+      }],
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [],
+      agentNotifications: [],
+    })
+
+    expect(hasVisibleSessionActivity(model)).toBe(true)
+    expect(getVisibleActivitySections(model).map((section) => section.id)).toEqual(['tasks'])
+    expect(model.badgeCount).toBe(0)
+  })
+
+  it('keeps completed Agent tool_use/tool_result rows visible without badge attention', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      messages: [agentMessages[0]!, agentMessages[1]!],
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [],
+      agentNotifications: [],
+    })
+
+    expect(hasVisibleSessionActivity(model)).toBe(true)
+    expect(getVisibleActivitySections(model).map((section) => section.id)).toEqual(['subagents'])
+    expect(model.badgeCount).toBe(0)
+  })
+
+  it('counts running and failed rows as visible while preserving badge attention semantics', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      tasks: [
+        task({ id: '1', subject: 'Implement', status: 'in_progress' }),
+      ],
+      completedAndDismissed: false,
+      backgroundTasks: [
+        background({ taskId: 'agent-1', toolUseId: 'tool-1', status: 'failed', taskType: 'local_agent' }),
+        background({ taskId: 'bg-2', toolUseId: 'tool-2', status: 'running', taskType: 'local_bash' }),
+      ],
+      agentNotifications: [],
+    })
+
+    expect(hasVisibleSessionActivity(model)).toBe(true)
+    expect(getVisibleActivitySections(model).map((section) => section.id)).toEqual([
+      'tasks',
+      'backgroundTasks',
+      'subagents',
+    ])
+    expect(model.badgeCount).toBe(3)
+  })
+
+  it('counts running team members as badge attention', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [],
+      agentNotifications: [],
+      teamMembers: [
+        { agentId: 'security', role: 'Security reviewer', status: 'running' },
+        { agentId: 'performance', role: 'Performance reviewer', status: 'completed' },
+      ],
+    })
+
+    expect(hasVisibleSessionActivity(model)).toBe(true)
+    expect(getVisibleActivitySections(model).map((section) => section.id)).toEqual(['team'])
+    expect(model.badgeCount).toBe(1)
+  })
+
+  it('counts error team members as badge attention', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [],
+      agentNotifications: [],
+      teamMembers: [
+        { agentId: 'security', role: 'Security reviewer', status: 'error' },
+      ],
+    })
+
+    expect(hasVisibleSessionActivity(model)).toBe(true)
+    expect(getVisibleActivitySections(model).map((section) => section.id)).toEqual(['team'])
+    expect(model.badgeCount).toBe(1)
+  })
+
+  it('does not count output-only rows as visible activity', () => {
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [],
+      agentNotifications: [
+        notification({
+          taskId: 'bg-bash-1',
+          toolUseId: 'bash-tool-1',
+          status: 'completed',
+          summary: 'Task completed',
+          outputFile: '/tmp/bg-test.log',
+        }),
+      ],
+    })
+
+    expect(model.sections.output.rows).toHaveLength(1)
+    expect(hasVisibleSessionActivity(model)).toBe(false)
+    expect(getVisibleActivitySections(model)).toEqual([])
+    expect(model.badgeCount).toBe(0)
+  })
+
+  it('does not keep Activity visible for dismissed finished background tasks', () => {
+    const dismissedTask = background({
+      taskId: 'bg-1',
+      toolUseId: 'tool-1',
+      status: 'completed',
+      taskType: 'local_bash',
+      startedAt: 1000,
+      description: 'Dismissed run',
+    })
+
+    const model = buildSessionActivityModel({
+      sessionId: 'session-1',
+      tasks: [],
+      completedAndDismissed: false,
+      backgroundTasks: [dismissedTask],
+      dismissedBackgroundTaskKeys: new Set([createBackgroundTaskDismissKey(dismissedTask)]),
+      agentNotifications: [],
+    })
+
+    expect(model.sections.backgroundTasks.rows).toHaveLength(0)
+    expect(hasVisibleSessionActivity(model)).toBe(false)
+    expect(getVisibleActivitySections(model)).toEqual([])
+    expect(model.badgeCount).toBe(0)
+  })
+
   it('counts incomplete tasks and running agent rows for the badge', () => {
     const model = buildSessionActivityModel({
       sessionId: 'session-1',
diff --git a/desktop/src/components/activity/sessionActivityModel.ts b/desktop/src/components/activity/sessionActivityModel.ts
index 4dfcfc2a..30772b50 100644
--- a/desktop/src/components/activity/sessionActivityModel.ts
+++ b/desktop/src/components/activity/sessionActivityModel.ts
@@ -56,7 +56,15 @@ export type BuildSessionActivityModelInput = {
   teamMembers?: TeamMember[]
 }
 
-const BADGE_STATUSES = new Set<ActivityStatus>(['pending', 'in_progress', 'running', 'failed'])
+export const VISIBLE_ACTIVITY_SECTION_ORDER = [
+  'tasks',
+  'team',
+  'backgroundTasks',
+  'subagents',
+  'sources',
+] as const satisfies readonly ActivitySectionId[]
+
+const BADGE_STATUSES = new Set<ActivityStatus>(['pending', 'in_progress', 'running', 'failed', 'error'])
 
 const SECTION_META: Record<ActivitySectionId, Pick<ActivitySection, 'title' | 'emptyLabel'>> = {
   output: { title: 'Output', emptyLabel: 'No output' },
@@ -87,6 +95,16 @@ function createSection(id: ActivitySectionId): ActivitySection {
   }
 }
 
+export function getVisibleActivitySections(model: SessionActivityModel): ActivitySection[] {
+  return VISIBLE_ACTIVITY_SECTION_ORDER
+    .map((sectionId) => model.sections[sectionId])
+    .filter((section) => section.rows.length > 0)
+}
+
+export function hasVisibleSessionActivity(model: SessionActivityModel): boolean {
+  return getVisibleActivitySections(model).length > 0
+}
+
 function isBadgeStatus(status: ActivityStatus): boolean {
   return BADGE_STATUSES.has(status)
 }
@@ -620,6 +638,11 @@ export function buildSessionActivityModel(input: BuildSessionActivityModelInput)
   for (const member of input.teamMembers ?? []) {
     sections.team.rows.push(buildTeamRow(member))
   }
+  for (const row of sections.team.rows) {
+    if (isBadgeStatus(row.status)) {
+      badgeCount += 1
+    }
+  }
 
   const subagentRowsByKey = new Map<string, ActivityRow>()
   const subagentKeyByTaskId = new Map<string, string>()
diff --git a/desktop/src/components/layout/TabBar.test.tsx b/desktop/src/components/layout/TabBar.test.tsx
index 395c7a3c..6bf1d156 100644
--- a/desktop/src/components/layout/TabBar.test.tsx
+++ b/desktop/src/components/layout/TabBar.test.tsx
@@ -2,9 +2,11 @@ import { act, cleanup, fireEvent, render, screen, waitFor } from '@testing-libra
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import '@testing-library/jest-dom'
 import type { PerSessionState } from '../../stores/chatStore'
-import type { ChatState } from '../../types/chat'
+import type { ChatState, UIMessage } from '../../types/chat'
 import { browserHost } from '../../lib/desktopHost/browserHost'
 
+type ToolUseMessage = Extract<UIMessage, { type: 'tool_use' }>
+
 const startDraggingMock = vi.hoisted(() => vi.fn(() => Promise.resolve()))
 const getCurrentWindowMock = vi.hoisted(() => vi.fn(() => ({
   startDragging: startDraggingMock,
@@ -47,6 +49,20 @@ function makeChatSession(chatState: ChatState): PerSessionState {
   }
 }
 
+const completedTodoWriteMessage = (overrides: Partial<ToolUseMessage> = {}): UIMessage => ({
+  id: 'todo-1',
+  type: 'tool_use',
+  toolName: 'TodoWrite',
+  toolUseId: 'todo-1',
+  input: {
+    todos: [
+      { content: 'Review existing implementation', status: 'completed' },
+    ],
+  },
+  timestamp: 1000,
+  ...overrides,
+})
+
 vi.mock('@tauri-apps/api/window', () => ({
   getCurrentWindow: getCurrentWindowMock,
 }))
@@ -182,6 +198,7 @@ describe('TabBar', () => {
     const { useBrowserPanelStore } = await import('../../stores/browserPanelStore')
     const { useActivityPanelStore } = await import('../../stores/activityPanelStore')
     const { useCLITaskStore } = await import('../../stores/cliTaskStore')
+    const { useTeamStore } = await import('../../stores/teamStore')
 
     useTabStore.setState({ tabs: [], activeTabId: null })
     useChatStore.setState({
@@ -200,17 +217,122 @@ describe('TabBar', () => {
     useBrowserPanelStore.setState(useBrowserPanelStore.getInitialState(), true)
     useActivityPanelStore.setState(useActivityPanelStore.getInitialState(), true)
     useCLITaskStore.setState(useCLITaskStore.getInitialState(), true)
+    useTeamStore.setState({
+      teams: [],
+      activeTeam: null,
+      memberColors: new Map(),
+      error: null,
+    })
 
     Reflect.deleteProperty(window, 'desktopHost')
     Reflect.deleteProperty(window, '__TAURI__')
   })
 
-  it('shows the activity button for active session tabs', async () => {
+  it('hides the activity button for no-activity chat session tabs', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useSessionStore } = await import('../../stores/sessionStore')
+    const sessionId = 'session-1'
+
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useSessionStore.setState({
+      sessions: [{ id: sessionId, title: 'Chat', workDir: '/tmp/project', workDirExists: true }],
+    } as Partial<ReturnType<typeof useSessionStore.getState>>)
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: makeChatSession('idle'),
+      },
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    expect(screen.queryByRole('button', { name: /activity/i })).not.toBeInTheDocument()
+  })
+
+  it('hides the activity button for output-only activity rows', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useSessionStore } = await import('../../stores/sessionStore')
+    const sessionId = 'session-1'
+    const chatSession = makeChatSession('idle')
+    chatSession.agentTaskNotifications = {
+      'bash-tool-1': {
+        taskId: 'bg-bash-1',
+        toolUseId: 'bash-tool-1',
+        status: 'completed',
+        summary: 'Task completed',
+        outputFile: '/tmp/bg-test.log',
+      },
+    }
+
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useSessionStore.setState({
+      sessions: [{ id: sessionId, title: 'Chat', workDir: '/tmp/project', workDirExists: true }],
+    } as Partial<ReturnType<typeof useSessionStore.getState>>)
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: chatSession,
+      },
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    expect(screen.queryByRole('button', { name: /activity/i })).not.toBeInTheDocument()
+    expect(screen.queryByTestId('session-activity-badge')).not.toBeInTheDocument()
+  })
+
+  it('shows the activity button for completed TodoWrite history without a badge', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useSessionStore } = await import('../../stores/sessionStore')
+    const sessionId = 'session-1'
+    const chatSession = makeChatSession('idle')
+    chatSession.messages = [completedTodoWriteMessage()]
+
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useSessionStore.setState({
+      sessions: [{ id: sessionId, title: 'Chat', workDir: '/tmp/project', workDirExists: true }],
+    } as Partial<ReturnType<typeof useSessionStore.getState>>)
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: chatSession,
+      },
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    expect(screen.getByRole('button', { name: /activity/i })).toBeInTheDocument()
+    expect(screen.queryByTestId('session-activity-badge')).not.toBeInTheDocument()
+  })
+
+  it('shows the activity button with a badge for running or failed activity', async () => {
     const { TabBar } = await import('./TabBar')
     const { useTabStore } = await import('../../stores/tabStore')
     const { useChatStore } = await import('../../stores/chatStore')
     const { useSessionStore } = await import('../../stores/sessionStore')
     const { useActivityPanelStore } = await import('../../stores/activityPanelStore')
+    const sessionId = 'session-1'
     const chatSession = makeChatSession('idle')
     chatSession.backgroundAgentTasks = {
       'agent-1': {
@@ -222,18 +344,27 @@ describe('TabBar', () => {
         startedAt: 1,
         updatedAt: 2,
       },
+      'agent-2': {
+        taskId: 'agent-2',
+        toolUseId: 'tool-2',
+        status: 'failed',
+        taskType: 'local_agent',
+        description: 'Report',
+        startedAt: 3,
+        updatedAt: 4,
+      },
     }
 
     useTabStore.setState({
-      tabs: [{ sessionId: 'session-1', title: 'Chat', type: 'session', status: 'idle' }],
-      activeTabId: 'session-1',
+      tabs: [{ sessionId, title: 'Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
     })
     useSessionStore.setState({
-      sessions: [{ id: 'session-1', title: 'Chat', workDir: '/tmp/project', workDirExists: true }],
+      sessions: [{ id: sessionId, title: 'Chat', workDir: '/tmp/project', workDirExists: true }],
     } as Partial<ReturnType<typeof useSessionStore.getState>>)
     useChatStore.setState({
       sessions: {
-        'session-1': chatSession,
+        [sessionId]: chatSession,
       },
       disconnectSession: vi.fn(),
     } as Partial<ReturnType<typeof useChatStore.getState>>)
@@ -244,8 +375,8 @@ describe('TabBar', () => {
 
     const button = screen.getByRole('button', { name: /activity/i })
     expect(button).toBeInTheDocument()
-    expect(screen.getByTestId('session-activity-badge')).toHaveTextContent('1')
-    expect(useActivityPanelStore.getState().isOpen('session-1')).toBe(false)
+    expect(screen.getByTestId('session-activity-badge')).toHaveTextContent('2')
+    expect(useActivityPanelStore.getState().isOpen(sessionId)).toBe(false)
     expect(button).toHaveAttribute('aria-expanded', 'false')
     expect(button).toHaveAttribute('aria-pressed', 'false')
 
@@ -254,7 +385,133 @@ describe('TabBar', () => {
     expect(button).toHaveAttribute('data-active', 'true')
     expect(button).toHaveAttribute('aria-expanded', 'true')
     expect(button).toHaveAttribute('aria-pressed', 'true')
-    expect(useActivityPanelStore.getState().isOpen('session-1')).toBe(true)
+    expect(useActivityPanelStore.getState().isOpen(sessionId)).toBe(true)
+  })
+
+  it('shows the activity button for team members associated with the active session', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useSessionStore } = await import('../../stores/sessionStore')
+    const { useTeamStore } = await import('../../stores/teamStore')
+    const sessionId = 'session-team'
+
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Team Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useSessionStore.setState({
+      sessions: [{ id: sessionId, title: 'Team Chat', workDir: '/tmp/project', workDirExists: true }],
+    } as Partial<ReturnType<typeof useSessionStore.getState>>)
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: makeChatSession('idle'),
+      },
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+    useTeamStore.setState({
+      activeTeam: {
+        name: 'review-team',
+        leadAgentId: 'lead',
+        leadSessionId: sessionId,
+        members: [
+          { agentId: 'lead', role: 'Lead', status: 'running' },
+          { agentId: 'security', role: 'Security reviewer', status: 'running' },
+        ],
+      },
+    } as Partial<ReturnType<typeof useTeamStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    expect(screen.getByRole('button', { name: /activity/i })).toBeInTheDocument()
+    expect(screen.getByTestId('session-activity-badge')).toHaveTextContent('1')
+  })
+
+  it('hides team-only activity when the active team belongs to another session', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useSessionStore } = await import('../../stores/sessionStore')
+    const { useTeamStore } = await import('../../stores/teamStore')
+    const sessionId = 'session-team'
+
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Team Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useSessionStore.setState({
+      sessions: [{ id: sessionId, title: 'Team Chat', workDir: '/tmp/project', workDirExists: true }],
+    } as Partial<ReturnType<typeof useSessionStore.getState>>)
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: makeChatSession('idle'),
+      },
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+    useTeamStore.setState({
+      activeTeam: {
+        name: 'other-review-team',
+        leadAgentId: 'lead',
+        leadSessionId: 'other-session',
+        members: [
+          { agentId: 'security', role: 'Security reviewer', status: 'running' },
+        ],
+      },
+    } as Partial<ReturnType<typeof useTeamStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    expect(screen.queryByRole('button', { name: /activity/i })).not.toBeInTheDocument()
+    expect(screen.queryByTestId('session-activity-badge')).not.toBeInTheDocument()
+  })
+
+  it('shows the activity button when team activity arrives after initial render', async () => {
+    const { TabBar } = await import('./TabBar')
+    const { useTabStore } = await import('../../stores/tabStore')
+    const { useChatStore } = await import('../../stores/chatStore')
+    const { useSessionStore } = await import('../../stores/sessionStore')
+    const { useTeamStore } = await import('../../stores/teamStore')
+    const sessionId = 'session-team'
+
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Team Chat', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useSessionStore.setState({
+      sessions: [{ id: sessionId, title: 'Team Chat', workDir: '/tmp/project', workDirExists: true }],
+    } as Partial<ReturnType<typeof useSessionStore.getState>>)
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: makeChatSession('idle'),
+      },
+      disconnectSession: vi.fn(),
+    } as Partial<ReturnType<typeof useChatStore.getState>>)
+
+    await act(async () => {
+      render(<TabBar />)
+    })
+
+    expect(screen.queryByRole('button', { name: /activity/i })).not.toBeInTheDocument()
+
+    await act(async () => {
+      useTeamStore.setState({
+        activeTeam: {
+          name: 'review-team',
+          leadAgentId: 'lead',
+          leadSessionId: sessionId,
+          members: [
+            { agentId: 'security', role: 'Security reviewer', status: 'error' },
+          ],
+        },
+      } as Partial<ReturnType<typeof useTeamStore.getState>>)
+    })
+
+    expect(screen.getByRole('button', { name: /activity/i })).toBeInTheDocument()
+    expect(screen.getByTestId('session-activity-badge')).toHaveTextContent('1')
   })
 
   it('does not show the activity button for settings tabs', async () => {
@@ -420,7 +677,7 @@ describe('TabBar', () => {
       render(<TabBar />)
     })
 
-    expect(screen.getByRole('button', { name: /activity/i })).toBeInTheDocument()
+    expect(screen.queryByRole('button', { name: /activity/i })).not.toBeInTheDocument()
     expect(screen.queryByTestId('session-activity-badge')).not.toBeInTheDocument()
   })
 
diff --git a/desktop/src/components/layout/TabBar.tsx b/desktop/src/components/layout/TabBar.tsx
index 3c55e3ab..e77ecc33 100644
--- a/desktop/src/components/layout/TabBar.tsx
+++ b/desktop/src/components/layout/TabBar.tsx
@@ -18,6 +18,7 @@ import { isPlaceholderSessionTitle } from '../../lib/sessionTitle'
 import { useWorkspacePanelStore } from '../../stores/workspacePanelStore'
 import { useTerminalPanelStore } from '../../stores/terminalPanelStore'
 import { useCLITaskStore } from '../../stores/cliTaskStore'
+import { useTeamStore } from '../../stores/teamStore'
 import { useTranslation } from '../../i18n'
 import { getDesktopHost } from '../../lib/desktopHost'
 import { hasRunningBackgroundTasks } from '../../lib/backgroundTasks'
@@ -25,7 +26,7 @@ import { WindowControls, showWindowControls } from './WindowControls'
 import { OpenProjectMenu } from './OpenProjectMenu'
 import { Folder, FolderOpen, SquareTerminal } from 'lucide-react'
 import { ActionDialog } from '../shared/ActionDialog'
-import { buildSessionActivityModel } from '../activity/sessionActivityModel'
+import { buildSessionActivityModel, hasVisibleSessionActivity } from '../activity/sessionActivityModel'
 import { SessionActivityButton } from '../activity/SessionActivityButton'
 import { useActivityPanelStore } from '../../stores/activityPanelStore'
 
@@ -110,12 +111,23 @@ export function TabBar() {
     () => new Set(dismissedBackgroundTaskKeyList),
     [dismissedBackgroundTaskKeyList],
   )
-  const activityBadgeCount = useChatStore((state) => {
-    if (!activeTabId || !isActiveSessionTab) return 0
+  const activityTeamMembers = useTeamStore(useShallow((state) => {
+    const activeTeam = state.activeTeam
+    if (!activeTabId || !activeTeam || activeTeam.leadSessionId !== activeTabId) {
+      return []
+    }
+    return activeTeam.members.filter((member) =>
+      !activeTeam.leadAgentId || member.agentId !== activeTeam.leadAgentId
+    )
+  }))
+  const activityState = useChatStore(useShallow((state) => {
+    if (!activeTabId || !isActiveSessionTab) {
+      return { badgeCount: 0, hasVisibleActivity: false }
+    }
     const sessionState = state.sessions[activeTabId]
     const includeCliTasks = cliTasksSessionId === activeTabId
 
-    return buildSessionActivityModel({
+    const model = buildSessionActivityModel({
       sessionId: activeTabId,
       messages: sessionState?.messages ?? [],
       tasks: includeCliTasks ? cliTasks : [],
@@ -123,8 +135,15 @@ export function TabBar() {
       backgroundTasks: Object.values(sessionState?.backgroundAgentTasks ?? {}),
       dismissedBackgroundTaskKeys,
       agentNotifications: Object.values(sessionState?.agentTaskNotifications ?? {}),
-    }).badgeCount
-  })
+      teamMembers: activityTeamMembers,
+    })
+    return {
+      badgeCount: model.badgeCount,
+      hasVisibleActivity: hasVisibleSessionActivity(model),
+    }
+  }))
+  const showActivityButton = activeTabId && activityState.hasVisibleActivity
+  const activityBadgeCount = activityState.badgeCount
 
   const moveTab = useTabStore((s) => s.moveTab)
   const scrollRef = useRef<HTMLDivElement>(null)
@@ -415,7 +434,7 @@ export function TabBar() {
       </div>
 
       <div className="flex shrink-0 items-center gap-1 border-l border-[var(--color-border)]/70 px-2">
-        {isActiveSessionTab && activeTabId && (
+        {showActivityButton && activeTabId && (
           <SessionActivityButton sessionId={activeTabId} badgeCount={activityBadgeCount} />
         )}
         {isDesktopRuntime && isActiveSessionTab && (
diff --git a/desktop/src/pages/ActiveSession.test.tsx b/desktop/src/pages/ActiveSession.test.tsx
index 6a6df80a..2d1ab8f4 100644
--- a/desktop/src/pages/ActiveSession.test.tsx
+++ b/desktop/src/pages/ActiveSession.test.tsx
@@ -1,5 +1,5 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { cleanup, createEvent, fireEvent, render, screen, within } from '@testing-library/react'
+import { cleanup, createEvent, fireEvent, render, screen, waitFor, within } from '@testing-library/react'
 import '@testing-library/jest-dom'
 import { act } from 'react'
 
@@ -579,6 +579,203 @@ describe('ActiveSession task polling', () => {
     expect(screen.queryByTestId('background-tasks-button')).not.toBeInTheDocument()
   })
 
+  it('does not render the activity panel when the store is open without visible activity', async () => {
+    const sessionId = 'activity-open-empty-session'
+
+    useActivityPanelStore.getState().open(sessionId)
+    useSessionStore.setState({
+      sessions: [{
+        id: sessionId,
+        title: 'Empty Activity Session',
+        createdAt: '2026-05-07T00:00:00.000Z',
+        modifiedAt: '2026-05-07T00:00:00.000Z',
+        messageCount: 1,
+        projectPath: '/workspace/project',
+        workDir: '/workspace/project',
+        workDirExists: true,
+      }],
+      activeSessionId: sessionId,
+      isLoading: false,
+      error: null,
+    })
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Empty Activity Session', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: {
+          messages: [{ id: 'msg-1', type: 'assistant_text', content: 'hello', timestamp: 1 }],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          streamingResponseChars: 0,
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          backgroundAgentTasks: {},
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    render(<ActiveSession />)
+
+    expect(screen.queryByTestId('session-activity-panel')).not.toBeInTheDocument()
+    await waitFor(() => {
+      expect(useActivityPanelStore.getState().isOpen(sessionId)).toBe(false)
+    })
+  })
+
+  it('renders completed historical TodoWrite activity in the rail', () => {
+    const sessionId = 'activity-todowrite-history-session'
+
+    useActivityPanelStore.getState().open(sessionId)
+    useSessionStore.setState({
+      sessions: [{
+        id: sessionId,
+        title: 'TodoWrite History Session',
+        createdAt: '2026-05-07T00:00:00.000Z',
+        modifiedAt: '2026-05-07T00:00:00.000Z',
+        messageCount: 1,
+        projectPath: '/workspace/project',
+        workDir: '/workspace/project',
+        workDirExists: true,
+      }],
+      activeSessionId: sessionId,
+      isLoading: false,
+      error: null,
+    })
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'TodoWrite History Session', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: {
+          messages: [{
+            id: 'todo-1',
+            type: 'tool_use',
+            toolName: 'TodoWrite',
+            toolUseId: 'todo-1',
+            input: {
+              todos: [
+                { content: 'Review historical implementation', status: 'completed' },
+              ],
+            },
+            timestamp: 1,
+          }],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          streamingResponseChars: 0,
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          backgroundAgentTasks: {},
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    render(<ActiveSession />)
+
+    const panel = screen.getByTestId('session-activity-panel')
+    expect(panel).toHaveAttribute('data-placement', 'rail')
+    expect(within(panel).getByText('Review historical implementation')).toBeInTheDocument()
+  })
+
+  it('ignores unrelated active team rows when deciding Activity visibility', async () => {
+    const sessionId = 'activity-unrelated-team-session'
+
+    useActivityPanelStore.getState().open(sessionId)
+    useTeamStore.setState({
+      teams: [],
+      activeTeam: {
+        name: 'other-team',
+        leadAgentId: 'team-lead@other-team',
+        leadSessionId: 'other-session',
+        members: [
+          {
+            agentId: 'security-reviewer@other-team',
+            role: 'security-reviewer',
+            status: 'running',
+            currentTask: 'Auditing another session',
+          },
+        ],
+      },
+      memberColors: new Map(),
+      error: null,
+    })
+    useSessionStore.setState({
+      sessions: [{
+        id: sessionId,
+        title: 'Unrelated Team Session',
+        createdAt: '2026-05-07T00:00:00.000Z',
+        modifiedAt: '2026-05-07T00:00:00.000Z',
+        messageCount: 1,
+        projectPath: '/workspace/project',
+        workDir: '/workspace/project',
+        workDirExists: true,
+      }],
+      activeSessionId: sessionId,
+      isLoading: false,
+      error: null,
+    })
+    useTabStore.setState({
+      tabs: [{ sessionId, title: 'Unrelated Team Session', type: 'session', status: 'idle' }],
+      activeTabId: sessionId,
+    })
+    useChatStore.setState({
+      sessions: {
+        [sessionId]: {
+          messages: [{ id: 'msg-1', type: 'assistant_text', content: 'hello', timestamp: 1 }],
+          chatState: 'idle',
+          connectionState: 'connected',
+          streamingText: '',
+          streamingToolInput: '',
+          activeToolUseId: null,
+          activeToolName: null,
+          activeThinkingId: null,
+          pendingPermission: null,
+          pendingComputerUsePermission: null,
+          tokenUsage: { input_tokens: 0, output_tokens: 0 },
+          streamingResponseChars: 0,
+          elapsedSeconds: 0,
+          statusVerb: '',
+          slashCommands: [],
+          backgroundAgentTasks: {},
+          agentTaskNotifications: {},
+          elapsedTimer: null,
+        },
+      },
+    })
+
+    render(<ActiveSession />)
+
+    expect(screen.queryByText('security-reviewer')).not.toBeInTheDocument()
+    expect(screen.queryByTestId('session-activity-panel')).not.toBeInTheDocument()
+    await waitFor(() => {
+      expect(useActivityPanelStore.getState().isOpen(sessionId)).toBe(false)
+    })
+  })
+
   it('opens a SubAgent detail tab from the activity panel', () => {
     const sessionId = 'activity-subagent-open-session'
 
@@ -755,7 +952,7 @@ describe('ActiveSession task polling', () => {
     ]))
   })
 
-  it('clears finished background tasks in the activity panel without hiding later runs', () => {
+  it('clears the last visible background task by closing Activity while preserving later runs', () => {
     const sessionId = 'activity-background-clear-session'
     const otherSessionId = 'activity-background-other-session'
 
@@ -856,6 +1053,8 @@ describe('ActiveSession task polling', () => {
     fireEvent.click(screen.getByRole('button', { name: /clear finished/i }))
 
     expect(screen.queryByText('Finished smoke run')).not.toBeInTheDocument()
+    expect(screen.queryByTestId('session-activity-panel')).not.toBeInTheDocument()
+    expect(useActivityPanelStore.getState().isOpen(sessionId)).toBe(false)
 
     act(() => {
       useTabStore.getState().setActiveTab(otherSessionId)
@@ -888,6 +1087,12 @@ describe('ActiveSession task polling', () => {
       }))
     })
 
+    expect(screen.queryByText('Finished smoke rerun')).not.toBeInTheDocument()
+
+    act(() => {
+      useActivityPanelStore.getState().open(sessionId)
+    })
+
     expect(screen.getByText('Finished smoke rerun')).toBeInTheDocument()
   })
 
diff --git a/desktop/src/pages/ActiveSession.tsx b/desktop/src/pages/ActiveSession.tsx
index d6c32b2e..593461a9 100644
--- a/desktop/src/pages/ActiveSession.tsx
+++ b/desktop/src/pages/ActiveSession.tsx
@@ -27,7 +27,7 @@ import { ChatInput } from '../components/chat/ChatInput'
 import { ComputerUsePermissionModal } from '../components/chat/ComputerUsePermissionModal'
 import { WorkbenchPanel } from '../components/workbench/WorkbenchPanel'
 import { SessionActivityPanel } from '../components/activity/SessionActivityPanel'
-import { buildSessionActivityModel } from '../components/activity/sessionActivityModel'
+import { buildSessionActivityModel, hasVisibleSessionActivity } from '../components/activity/sessionActivityModel'
 import { TerminalSettings } from './TerminalSettings'
 import type { SessionListItem } from '../types/session'
 import type { ActiveGoalState, TokenUsage } from '../types/chat'
@@ -402,11 +402,11 @@ export function ActiveSession() {
     hasRunningBackgroundTasks
   const totalTokens = getTokenUsageTotal(tokenUsage)
   const activityTeamMembers = useMemo(() => {
-    if (!activeTeam) return []
+    if (!activeTeam || activeTeam.leadSessionId !== activeTabId) return []
     return activeTeam.members.filter((member) =>
       !activeTeam.leadAgentId || member.agentId !== activeTeam.leadAgentId
     )
-  }, [activeTeam])
+  }, [activeTabId, activeTeam])
 
   useEffect(() => {
     if (!activeTabId) return
@@ -441,6 +441,13 @@ export function ActiveSession() {
     messages,
     trackedTaskSessionId,
   ])
+  const hasVisibleActivity = activityModel ? hasVisibleSessionActivity(activityModel) : false
+
+  useEffect(() => {
+    if (!activeTabId || !isActivityPanelOpen || hasVisibleActivity) return
+    closeActivityPanel(activeTabId)
+  }, [activeTabId, closeActivityPanel, hasVisibleActivity, isActivityPanelOpen])
+
   const handleOpenSubagentRun = useCallback((payload: { sessionId: string; toolUseId: string; title: string }) => {
     useTabStore.getState().openSubagentTab(payload.sessionId, payload.toolUseId, payload.title)
   }, [])
@@ -638,7 +645,7 @@ export function ActiveSession() {
             </>
           )}
 
-          {activityModel && isMobileLayout && !isMemberSession && isSessionTabState(activeTabId, activeTabType) ? (
+          {activityModel && hasVisibleActivity && isMobileLayout && !isMemberSession && isSessionTabState(activeTabId, activeTabType) ? (
             <SessionActivityPanel
               model={activityModel}
               open={isActivityPanelOpen}
@@ -683,7 +690,7 @@ export function ActiveSession() {
           ) : null}
         </div>
 
-        {activityModel && !isMobileLayout && !isMemberSession && isSessionTabState(activeTabId, activeTabType) ? (
+        {activityModel && hasVisibleActivity && !isMobileLayout && !isMemberSession && isSessionTabState(activeTabId, activeTabType) ? (
           <SessionActivityPanel
             model={activityModel}
             open={isActivityPanelOpen}