diff --git a/frontend/src/components/navigation/MobileTabBar.test.tsx b/frontend/src/components/navigation/MobileTabBar.test.tsx
index 79403a57..fd06fb8b 100644
--- a/frontend/src/components/navigation/MobileTabBar.test.tsx
+++ b/frontend/src/components/navigation/MobileTabBar.test.tsx
@@ -77,7 +77,7 @@ describe('MobileTabBar', () => {
     expect(screen.getByText('Schedules')).toBeInTheDocument()
   })
 
-  it('navigates to /assistant when assistant is clicked from repo context', async () => {
+  it('navigates to assistant session list when assistant is clicked from repo context', async () => {
     vi.mocked(useMobile).mockReturnValue(true)
     const queryClient = new QueryClient()
     const user = userEvent.setup()
@@ -96,10 +96,10 @@ describe('MobileTabBar', () => {
     )
 
     await user.click(screen.getByRole('button', { name: 'Assistant' }))
-    expect(screen.getByTestId('location')).toHaveTextContent('/assistant')
+    expect(screen.getByTestId('location')).toHaveTextContent('/assistant?view=sessions')
   })
 
-  it('navigates to assistant route when assistant is clicked without repo id', async () => {
+  it('navigates to assistant session list when assistant is clicked without repo id', async () => {
     vi.mocked(useMobile).mockReturnValue(true)
     const queryClient = new QueryClient()
     const user = userEvent.setup()
@@ -118,7 +118,7 @@ describe('MobileTabBar', () => {
     )
 
     await user.click(screen.getByRole('button', { name: 'Assistant' }))
-    expect(screen.getByTestId('location')).toHaveTextContent('/assistant')
+    expect(screen.getByTestId('location')).toHaveTextContent('/assistant?view=sessions')
   })
 
   it('renders schedule tabs on /repos/:id/schedules path', () => {
diff --git a/frontend/src/components/navigation/MobileTabBar.tsx b/frontend/src/components/navigation/MobileTabBar.tsx
index c20880bc..c4b0b80b 100644
--- a/frontend/src/components/navigation/MobileTabBar.tsx
+++ b/frontend/src/components/navigation/MobileTabBar.tsx
@@ -6,7 +6,7 @@ import { useMobile } from '@/hooks/useMobile'
 import { useMobileTabBar } from '@/hooks/useMobileTabBar'
 import { useUrlParams } from '@/hooks/useUrlParams'
 import { useScheduleUrlState, type ScheduleTab } from '@/hooks/useScheduleUrlState'
-import { getAssistantPath, isAssistantPath } from '@/lib/navigation'
+import { getAssistantPath, getAssistantSessionListPath, isAssistantPath } from '@/lib/navigation'
 
 interface TabDef {
   key: string
@@ -74,7 +74,7 @@ function buildGlobalTabs({ pathname, openSheet, open, close, navigate, isInsideR
 
   const handleAssistantClick = () => {
     close()
-    navigate(getAssistantPath())
+    navigate(getAssistantSessionListPath())
   }
 
   return [
@@ -97,7 +97,7 @@ function buildGlobalTabs({ pathname, openSheet, open, close, navigate, isInsideR
       label: 'Assistant',
       icon: Bot,
       onClick: handleAssistantClick,
-      active: isAssistantPath(pathname) && !openSheet,
+      active: (pathname === getAssistantPath() || isAssistantPath(pathname)) && !openSheet,
     },
     {
       key: 'schedules',
diff --git a/frontend/src/components/navigation/moreDrawerItems.test.ts b/frontend/src/components/navigation/moreDrawerItems.test.ts
index 6ea63961..bfb6283a 100644
--- a/frontend/src/components/navigation/moreDrawerItems.test.ts
+++ b/frontend/src/components/navigation/moreDrawerItems.test.ts
@@ -90,7 +90,7 @@ describe('buildNavModel', () => {
     expect(model.primary[0].key).toBe('new-repo')
     expect(model.primary[0].onSelect).toBe('new-repo')
     expect(model.primary[1].key).toBe('assistant')
-    expect(model.primary[1].to).toBe('/assistant')
+    expect(model.primary[1].to).toBe('/assistant?view=sessions')
   })
 
   it('returns new-session and assistant primary CTAs for repo detail', () => {
@@ -99,7 +99,7 @@ describe('buildNavModel', () => {
     expect(model.primary[0].key).toBe('new-session')
     expect(model.primary[0].onSelect).toBe('new-session')
     expect(model.primary[1].key).toBe('assistant')
-    expect(model.primary[1].to).toBe('/assistant')
+    expect(model.primary[1].to).toBe('/assistant?view=sessions')
   })
 
   it('returns new-session and assistant primary CTAs for session detail', () => {
@@ -109,7 +109,7 @@ describe('buildNavModel', () => {
     expect(model.primary[0].onSelect).toBe('new-session')
     expect(model.primary[0].variant).toBe('primary')
     expect(model.primary[1].key).toBe('assistant')
-    expect(model.primary[1].to).toBe('/assistant')
+    expect(model.primary[1].to).toBe('/assistant?view=sessions')
     expect(model.primary[1].variant).toBe('secondary')
   })
 
@@ -120,7 +120,7 @@ describe('buildNavModel', () => {
     expect(model.primary[0].onSelect).toBe('new-session')
     expect(model.primary[0].variant).toBe('primary')
     expect(model.primary[1].key).toBe('assistant')
-    expect(model.primary[1].to).toBe('/assistant')
+    expect(model.primary[1].to).toBe('/assistant?view=sessions')
     expect(model.primary[1].variant).toBe('secondary')
   })
 
@@ -131,7 +131,7 @@ describe('buildNavModel', () => {
     expect(model.primary[0].onSelect).toBe('new-session')
     expect(model.primary[0].variant).toBe('primary')
     expect(model.primary[1].key).toBe('assistant')
-    expect(model.primary[1].to).toBe('/assistant')
+    expect(model.primary[1].to).toBe('/assistant?view=sessions')
     expect(model.primary[1].variant).toBe('secondary')
   })
 
@@ -141,21 +141,21 @@ describe('buildNavModel', () => {
     expect(model1.primary[0].key).toBe('new-schedule')
     expect(model1.primary[0].onSelect).toBe('new-schedule')
     expect(model1.primary[1].key).toBe('assistant')
-    expect(model1.primary[1].to).toBe('/assistant')
+    expect(model1.primary[1].to).toBe('/assistant?view=sessions')
 
     const model2 = buildNavModel('/repos/5/schedules')
     expect(model2.primary).toHaveLength(2)
     expect(model2.primary[0].key).toBe('new-schedule')
     expect(model2.primary[0].onSelect).toBe('new-schedule')
     expect(model2.primary[1].key).toBe('assistant')
-    expect(model2.primary[1].to).toBe('/assistant')
+    expect(model2.primary[1].to).toBe('/assistant?view=sessions')
   })
 
   it('returns assistant primary for unknown routes', () => {
     const model = buildNavModel('/unknown/path')
     expect(model.primary).toHaveLength(1)
     expect(model.primary[0].key).toBe('assistant')
-    expect(model.primary[0].to).toBe('/assistant')
+    expect(model.primary[0].to).toBe('/assistant?view=sessions')
   })
 
   it('preserves backwards compatibility with buildMoreItems', () => {
diff --git a/frontend/src/components/navigation/moreDrawerItems.ts b/frontend/src/components/navigation/moreDrawerItems.ts
index 23d451cf..8d7c0b3e 100644
--- a/frontend/src/components/navigation/moreDrawerItems.ts
+++ b/frontend/src/components/navigation/moreDrawerItems.ts
@@ -1,6 +1,6 @@
 import type { LucideIcon } from 'lucide-react'
 import { Plug, Sparkles, ShieldOff, CalendarClock, GitCommitHorizontal, Code2, Settings, LogOut, Plus, Bot, Folder, Clock, SquarePlus } from 'lucide-react'
-import { getAssistantPath, isAssistantPath } from '@/lib/navigation'
+import { getAssistantSessionListPath, isAssistantPath } from '@/lib/navigation'
 
 export interface MoreDrawerItem {
   key: string
@@ -30,7 +30,7 @@ function getAssistantNavItem(_pathname: string, variant: NavPrimaryCta['variant'
     key: 'assistant',
     label: 'Assistant',
     icon: Bot,
-    to: getAssistantPath(),
+    to: getAssistantSessionListPath(),
     variant,
   }
 }
diff --git a/frontend/src/hooks/__tests__/useLoadSkill.test.tsx b/frontend/src/hooks/__tests__/useLoadSkill.test.tsx
index 51f53c1f..2b11f1bd 100644
--- a/frontend/src/hooks/__tests__/useLoadSkill.test.tsx
+++ b/frontend/src/hooks/__tests__/useLoadSkill.test.tsx
@@ -5,6 +5,7 @@ import { useLoadSkill } from '../useOpenCode'
 import type { MessageWithParts } from '../../api/types'
 
 import { showToast } from '../../lib/toast'
+import { useSessionStatus } from '../../stores/sessionStatusStore'
 
 const mocks = vi.hoisted(() => ({
   sendCommand: vi.fn(),
@@ -38,6 +39,7 @@ const createWrapper = () => {
 describe('useLoadSkill', () => {
   beforeEach(() => {
     vi.clearAllMocks()
+    useSessionStatus.getState().replaceStatuses({})
   })
 
   it('calls sendCommand with correct parameters when mutate is called', async () => {
@@ -161,13 +163,29 @@ describe('useLoadSkill', () => {
     })
   })
 
-  it('sets session status to busy on mutate and idle on error', async () => {
+  it('sets session status to busy on mutate', async () => {
+    mocks.sendCommand.mockReturnValue(new Promise(() => {}))
+
+    const { result } = renderHook(
+      () => useLoadSkill('http://localhost:5551', 'test-session-id', '/test/dir'),
+      { wrapper: createWrapper() },
+    )
+
+    result.current.mutate({ skillName: 'my-skill' })
+
+    await waitFor(() => {
+      expect(useSessionStatus.getState().getStatus('test-session-id').type).toBe('busy')
+    })
+  })
+
+  it('rolls back to idle on mutation error', async () => {
     const queryClient = new QueryClient({
       defaultOptions: {
         queries: { retry: false },
         mutations: { retry: false },
       },
     })
+
     const testError = new Error('Command failed')
     mocks.sendCommand.mockRejectedValue(testError)
 
@@ -182,6 +200,33 @@ describe('useLoadSkill', () => {
       expect(result.current.isError).toBe(true)
     })
 
+    expect(useSessionStatus.getState().getStatus('test-session-id').type).toBe('idle')
+  })
+
+  it('does not set session status when sessionID is undefined', async () => {
+    const queryClient = new QueryClient({
+      defaultOptions: {
+        queries: { retry: false },
+        mutations: { retry: false },
+      },
+    })
+
+    mocks.sendCommand.mockReturnValue(new Promise(() => {}))
+
+    const { result } = renderHook(
+      () => useLoadSkill('http://localhost:5551', undefined, '/test/dir'),
+      { wrapper: ({ children }) => <QueryClientProvider client={queryClient}>{children}</QueryClientProvider> },
+    )
+
+    result.current.mutate({ skillName: 'my-skill' })
+
+    await waitFor(() => {
+      expect(result.current.isError).toBe(true)
+    })
+
+    expect(result.current.error).toBeInstanceOf(Error)
+    expect((result.current.error as Error).message).toBe('No active session')
+    expect(useSessionStatus.getState().getStatus('test-session-id').type).toBe('idle')
   })
 
   it('removes optimistic message from cache on error', async () => {
diff --git a/frontend/src/hooks/useOpenCode.ts b/frontend/src/hooks/useOpenCode.ts
index e0122c32..382a4d31 100644
--- a/frontend/src/hooks/useOpenCode.ts
+++ b/frontend/src/hooks/useOpenCode.ts
@@ -12,6 +12,8 @@ import type { paths, components } from "../api/opencode-types";
 import { parseNetworkError } from "../lib/opencode-errors";
 import { showToast } from "../lib/toast";
 import { useSendErrorStore } from "../stores/sendErrorStore";
+import { beginOptimisticBusy, rollbackOptimisticBusy } from "../stores/sessionStatusStore";
+import type { SessionStatusType } from "../stores/sessionStatusStore";
 import { invalidateSessionListCaches, messagesQueryKey } from "../lib/queryInvalidation";
 
 type AssistantMessage = components["schemas"]["AssistantMessage"];
@@ -22,6 +24,8 @@ type SendPromptRequest = NonNullable<
 
 type SendCommandResponse = paths["/session/{sessionID}/command"]["post"]["responses"]["200"]["content"]["application/json"];
 
+type OptimisticBusyContext = { previousBusyStatus: SessionStatusType };
+
 const parseModelString = (model: string) => {
   const [providerID, ...rest] = model.split("/");
   const modelID = rest.join("/");
@@ -477,8 +481,13 @@ export const useSendPrompt = (opcodeUrl: string | null | undefined, directory?:
 
       return { optimisticUserID, response, queued: false };
     },
-    onError: (error, variables) => {
+    onMutate: ({ sessionID }): OptimisticBusyContext => ({
+      previousBusyStatus: beginOptimisticBusy(sessionID),
+    }),
+    onError: (error, variables, context: OptimisticBusyContext | undefined) => {
       const { sessionID } = variables;
+      rollbackOptimisticBusy(sessionID, context?.previousBusyStatus ?? { type: 'idle' });
+
       const queryKey = messagesQueryKey(opcodeUrl, sessionID, directory);
 
       queryClient.setQueryData<MessageWithParts[]>(
@@ -726,8 +735,12 @@ export const useSendShell = (opcodeUrl: string | null | undefined, directory?: s
 
       return { optimisticUserID, response };
     },
-    onError: (_, variables) => {
+    onMutate: ({ sessionID }): OptimisticBusyContext => ({
+      previousBusyStatus: beginOptimisticBusy(sessionID),
+    }),
+    onError: (_error, variables, context: OptimisticBusyContext | undefined) => {
       const { sessionID } = variables;
+      rollbackOptimisticBusy(sessionID, context?.previousBusyStatus ?? { type: 'idle' });
       queryClient.setQueryData<MessageWithParts[]>(
         messagesQueryKey(opcodeUrl, sessionID, directory),
         (old) => {
@@ -788,7 +801,8 @@ export const useLoadSkill = (
   return useMutation<
     { optimisticUserID: string; response: SendCommandResponse },
     Error,
-    { skillName: string }
+    { skillName: string },
+    OptimisticBusyContext | undefined
   >({
     mutationFn: async ({ skillName }: { skillName: string }) => {
       if (!client) throw new Error("No OpenCode client available");
@@ -817,7 +831,14 @@ export const useLoadSkill = (
       const response = await client.sendCommand(sessionID, { command: skillName, arguments: "" });
       return { optimisticUserID, response };
     },
-    onError: (error) => {
+    onMutate: () => {
+      if (!sessionID) return undefined;
+      return { previousBusyStatus: beginOptimisticBusy(sessionID) };
+    },
+    onError: (error, _variables, context: OptimisticBusyContext | undefined) => {
+      if (sessionID && context?.previousBusyStatus) {
+        rollbackOptimisticBusy(sessionID, context.previousBusyStatus);
+      }
       if (sessionID) {
         const queryKey = messagesQueryKey(opcodeUrl, sessionID, directory);
         queryClient.setQueryData<MessageWithParts[]>(
diff --git a/frontend/src/hooks/useSendPrompt.test.ts b/frontend/src/hooks/useSendPrompt.test.ts
index 4c36a341..8423a318 100644
--- a/frontend/src/hooks/useSendPrompt.test.ts
+++ b/frontend/src/hooks/useSendPrompt.test.ts
@@ -1,9 +1,10 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest'
-import { renderHook } from '@testing-library/react'
+import { renderHook, waitFor } from '@testing-library/react'
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
 import { createElement } from 'react'
 import { useSendPrompt } from './useOpenCode'
 import { FetchError } from '../api/fetchWrapper'
+import { useSessionStatus } from '../stores/sessionStatusStore'
 
 const mockSendPrompt = vi.fn()
 const mockSendPromptAsync = vi.fn()
@@ -19,10 +20,6 @@ vi.mock('../api/opencode', async () => {
   }
 })
 
-vi.mock('@/stores/sessionStatusStore', () => ({
-  useSessionStatus: vi.fn(() => vi.fn()),
-}))
-
 vi.mock('../lib/toast', () => ({
   showToast: { error: vi.fn() },
 }))
@@ -62,6 +59,7 @@ describe('useSendPrompt', () => {
 
   beforeEach(() => {
     vi.clearAllMocks()
+    useSessionStatus.getState().replaceStatuses({})
     queryClient = createTestQueryClient()
     mockSendPrompt.mockResolvedValue({
       info: { id: 'test-response' },
@@ -194,4 +192,25 @@ describe('useSendPrompt', () => {
 
     expect(mockClearError).toHaveBeenCalledWith('session-2')
   })
+
+  it('sets session status to busy immediately on send', async () => {
+    mockSendPrompt.mockReturnValue(new Promise(() => {}))
+
+    const { result } = renderHookWithProviders()
+    result.current.mutate({ sessionID: 'busy-session', prompt: 'Hi' })
+
+    await waitFor(() => {
+      expect(useSessionStatus.getState().getStatus('busy-session').type).toBe('busy')
+    })
+  })
+
+  it('rolls back to idle when send fails', async () => {
+    mockSendPrompt.mockRejectedValue(new Error('boom'))
+
+    const { result } = renderHookWithProviders()
+    result.current.mutate({ sessionID: 'busy-session', prompt: 'Hi' })
+
+    await waitFor(() => expect(result.current.isError).toBe(true))
+    expect(useSessionStatus.getState().getStatus('busy-session').type).toBe('idle')
+  })
 })
diff --git a/frontend/src/hooks/useSendShell.test.ts b/frontend/src/hooks/useSendShell.test.ts
new file mode 100644
index 00000000..e62ec90a
--- /dev/null
+++ b/frontend/src/hooks/useSendShell.test.ts
@@ -0,0 +1,71 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+import { renderHook, waitFor } from '@testing-library/react'
+import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
+import { createElement } from 'react'
+import { useSendShell } from './useOpenCode'
+import { useSessionStatus } from '../stores/sessionStatusStore'
+
+const mockSendShell = vi.fn()
+
+vi.mock('../api/opencode', async () => {
+  const actual = await vi.importActual('../api/opencode')
+  return {
+    ...actual,
+    OpenCodeClient: vi.fn().mockImplementation(() => ({
+      sendShell: mockSendShell,
+    })),
+  }
+})
+
+vi.mock('../lib/toast', () => ({
+  showToast: { error: vi.fn() },
+}))
+
+const createTestQueryClient = () =>
+  new QueryClient({
+    defaultOptions: {
+      queries: {
+        retry: false,
+      },
+    },
+  })
+
+describe('useSendShell', () => {
+  let queryClient: QueryClient
+
+  beforeEach(() => {
+    vi.clearAllMocks()
+    useSessionStatus.getState().replaceStatuses({})
+    queryClient = createTestQueryClient()
+  })
+
+  const renderHookWithProviders = () =>
+    renderHook(
+      () => useSendShell('http://localhost:5551', '/test'),
+      {
+        wrapper: ({ children }) =>
+          createElement(QueryClientProvider, { client: queryClient }, children),
+      }
+    )
+
+  it('sets session status to busy on shell send', async () => {
+    mockSendShell.mockReturnValue(new Promise(() => {}))
+
+    const { result } = renderHookWithProviders()
+    result.current.mutate({ sessionID: 'shell-session', command: 'ls', agent: 'general' })
+
+    await waitFor(() => {
+      expect(useSessionStatus.getState().getStatus('shell-session').type).toBe('busy')
+    })
+  })
+
+  it('rolls back to idle when shell send fails', async () => {
+    mockSendShell.mockRejectedValue(new Error('boom'))
+
+    const { result } = renderHookWithProviders()
+    result.current.mutate({ sessionID: 'shell-session', command: 'ls', agent: 'general' })
+
+    await waitFor(() => expect(result.current.isError).toBe(true))
+    expect(useSessionStatus.getState().getStatus('shell-session').type).toBe('idle')
+  })
+})
diff --git a/frontend/src/pages/RepoDetail.tsx b/frontend/src/pages/RepoDetail.tsx
index a9de77b0..dd53cc22 100644
--- a/frontend/src/pages/RepoDetail.tsx
+++ b/frontend/src/pages/RepoDetail.tsx
@@ -108,7 +108,11 @@ export function RepoDetail() {
   const sessionUrl = useCallback(
     (sessionId: string) => {
       const base = `/repos/${repoId}/sessions/${sessionId}`;
-      return activeTab === 'workspaces' ? `${base}?repoTab=workspaces` : base;
+      const params = new URLSearchParams();
+      if (repoId === 0) params.set('assistant', '1');
+      if (activeTab === 'workspaces') params.set('repoTab', 'workspaces');
+      const search = params.toString();
+      return search ? `${base}?${search}` : base;
     },
     [repoId, activeTab],
   );
diff --git a/frontend/src/stores/sessionStatusStore.test.ts b/frontend/src/stores/sessionStatusStore.test.ts
new file mode 100644
index 00000000..f1b4042e
--- /dev/null
+++ b/frontend/src/stores/sessionStatusStore.test.ts
@@ -0,0 +1,34 @@
+import { describe, it, expect, beforeEach } from 'vitest'
+import { useSessionStatus, beginOptimisticBusy, rollbackOptimisticBusy } from './sessionStatusStore'
+
+describe('optimistic busy helpers', () => {
+  beforeEach(() => {
+    useSessionStatus.getState().replaceStatuses({})
+  })
+
+  it('beginOptimisticBusy on idle session sets busy and returns idle', () => {
+    const previous = beginOptimisticBusy('session-1')
+    expect(previous).toEqual({ type: 'idle' })
+    expect(useSessionStatus.getState().getStatus('session-1')).toEqual({ type: 'busy' })
+  })
+
+  it('rollbackOptimisticBusy returns session to idle', () => {
+    beginOptimisticBusy('session-1')
+    rollbackOptimisticBusy('session-1', { type: 'idle' })
+    expect(useSessionStatus.getState().getStatus('session-1')).toEqual({ type: 'idle' })
+  })
+
+  it('beginOptimisticBusy on already-busy session returns busy and keeps busy', () => {
+    useSessionStatus.getState().setStatus('session-1', { type: 'busy' })
+    const previous = beginOptimisticBusy('session-1')
+    expect(previous).toEqual({ type: 'busy' })
+    expect(useSessionStatus.getState().getStatus('session-1')).toEqual({ type: 'busy' })
+    rollbackOptimisticBusy('session-1', { type: 'busy' })
+    expect(useSessionStatus.getState().getStatus('session-1')).toEqual({ type: 'busy' })
+  })
+
+  it('busy state is scoped per sessionID', () => {
+    beginOptimisticBusy('a')
+    expect(useSessionStatus.getState().getStatus('b')).toEqual({ type: 'idle' })
+  })
+})
diff --git a/frontend/src/stores/sessionStatusStore.ts b/frontend/src/stores/sessionStatusStore.ts
index 823ba340..a7f4ef14 100644
--- a/frontend/src/stores/sessionStatusStore.ts
+++ b/frontend/src/stores/sessionStatusStore.ts
@@ -104,3 +104,17 @@ export const useSessionStatusForSession = (sessionID: string | undefined): Sessi
     sessionID ? (state.statuses.get(sessionID) ?? DEFAULT_STATUS) : DEFAULT_STATUS
   )
 }
+
+export function beginOptimisticBusy(sessionID: string): SessionStatusType {
+  const { getStatus, setStatus } = useSessionStatus.getState()
+  const previous = getStatus(sessionID)
+  setStatus(sessionID, { type: 'busy' })
+  return previous
+}
+
+export function rollbackOptimisticBusy(
+  sessionID: string,
+  previous: SessionStatusType,
+): void {
+  useSessionStatus.getState().setStatus(sessionID, previous)
+}