diff --git a/src/renderer/src/stores/ui/session.ts b/src/renderer/src/stores/ui/session.ts
index 0d98c17e9..c37e95743 100644
--- a/src/renderer/src/stores/ui/session.ts
+++ b/src/renderer/src/stores/ui/session.ts
@@ -45,6 +45,9 @@ export interface SessionGroup {
 
 export type GroupMode = 'time' | 'project'
 
+const SIDEBAR_GROUP_MODE_KEY = 'sidebar_group_mode'
+const DEFAULT_GROUP_MODE: GroupMode = 'project'
+
 // --- Helper Functions ---
 
 function mapSessionStatus(status: string): UISessionStatus {
@@ -133,7 +136,7 @@ function groupByProject(sessions: UISession[]): SessionGroup[] {
     projectMap.get(dir)!.push(session)
   }
   return Array.from(projectMap.entries()).map(([dir, sessions]) => ({
-    label: dir === '__no_project__' ? 'common.project.none' : (dir.split('/').pop() ?? dir),
+    label: dir === '__no_project__' ? 'common.project.none' : (dir.split(/[\\/]/).pop() ?? dir),
     labelKey: dir === '__no_project__' ? 'common.project.none' : undefined,
     sessions
   }))
@@ -159,15 +162,20 @@ function getContentType(format: 'markdown' | 'html' | 'txt' | 'nowledge-mem'): s
 export const useSessionStore = defineStore('session', () => {
   const agentSessionPresenter = usePresenter('agentSessionPresenter')
   const tabPresenter = usePresenter('tabPresenter')
+  const configPresenter = usePresenter('configPresenter', { safeCall: false })
   const pageRouter = usePageRouterStore()
   const messageStore = useMessageStore()
   const myWebContentsId = getCurrentWebContentsId()
   let rendererReadyNotified = false
+  let groupModeLoadPromise: Promise<void> | null = null
+  let groupModeWritePromise: Promise<void> = Promise.resolve()
+  let hasLoadedGroupMode = false
+  let groupModeUpdateVersion = 0
 
   // --- State ---
   const sessions = ref<UISession[]>([])
   const activeSessionId = ref<string | null>(null)
-  const groupMode = ref<GroupMode>('time')
+  const groupMode = ref<GroupMode>(DEFAULT_GROUP_MODE)
   const loading = ref(false)
   const error = ref<string | null>(null)
 
@@ -179,6 +187,41 @@ export const useSessionStore = defineStore('session', () => {
 
   notifyRendererReady()
 
+  const normalizeGroupMode = (value: unknown): GroupMode =>
+    value === 'time' || value === 'project' ? value : DEFAULT_GROUP_MODE
+
+  const loadGroupModePreference = async (): Promise<void> => {
+    const loadVersion = groupModeUpdateVersion
+
+    try {
+      const savedGroupMode = await configPresenter.getSetting<GroupMode>(SIDEBAR_GROUP_MODE_KEY)
+      if (groupModeUpdateVersion === loadVersion) {
+        groupMode.value = normalizeGroupMode(savedGroupMode)
+      }
+    } catch (error) {
+      if (groupModeUpdateVersion === loadVersion) {
+        groupMode.value = DEFAULT_GROUP_MODE
+      }
+      console.warn('[sessionStore] Failed to load sidebar group mode:', error)
+    } finally {
+      hasLoadedGroupMode = true
+    }
+  }
+
+  const ensureGroupModeLoaded = async (): Promise<void> => {
+    if (hasLoadedGroupMode) {
+      return
+    }
+
+    if (!groupModeLoadPromise) {
+      groupModeLoadPromise = loadGroupModePreference().finally(() => {
+        groupModeLoadPromise = null
+      })
+    }
+
+    await groupModeLoadPromise
+  }
+
   // --- Getters ---
   const activeSession: ComputedRef<UISession | undefined> = computed(() =>
     sessions.value.find((s) => s.id === activeSessionId.value)
@@ -194,6 +237,7 @@ export const useSessionStore = defineStore('session', () => {
     loading.value = true
     error.value = null
     try {
+      await ensureGroupModeLoaded()
       const webContentsId = getCurrentWebContentsId()
       const previousActiveSessionId = activeSessionId.value
       const [result, activeSession] = await Promise.all([
@@ -382,8 +426,26 @@ export const useSessionStore = defineStore('session', () => {
     }
   }
 
-  function toggleGroupMode(): void {
-    groupMode.value = groupMode.value === 'time' ? 'project' : 'time'
+  async function toggleGroupMode(): Promise<void> {
+    const previousMode = groupMode.value
+    groupMode.value = previousMode === 'time' ? 'project' : 'time'
+    const localVersion = ++groupModeUpdateVersion
+
+    groupModeWritePromise = groupModeWritePromise.then(async () => {
+      try {
+        await configPresenter.setSetting(SIDEBAR_GROUP_MODE_KEY, groupMode.value)
+        if (localVersion !== groupModeUpdateVersion) {
+          return
+        }
+      } catch (error) {
+        if (localVersion === groupModeUpdateVersion) {
+          groupMode.value = previousMode
+        }
+        console.warn('[sessionStore] Failed to persist sidebar group mode:', error)
+      }
+    })
+
+    await groupModeWritePromise
   }
 
   function getPinnedSessions(agentId: string | null): UISession[] {
@@ -438,6 +500,7 @@ export const useSessionStore = defineStore('session', () => {
     }
   })
   registerStoreCleanup(cleanupIpcBindings)
+  void ensureGroupModeLoaded()
 
   return {
     sessions,
diff --git a/test/renderer/stores/sessionStore.test.ts b/test/renderer/stores/sessionStore.test.ts
index 9ca6c5c89..cd1d9469a 100644
--- a/test/renderer/stores/sessionStore.test.ts
+++ b/test/renderer/stores/sessionStore.test.ts
@@ -1,6 +1,14 @@
 import { describe, expect, it, vi } from 'vitest'
 
-const setupStore = async () => {
+type SetupStoreOptions = {
+  initialSettings?: Record<string, unknown>
+  failGetSetting?: boolean
+  failSetSetting?: boolean
+}
+
+const SIDEBAR_GROUP_MODE_KEY = 'sidebar_group_mode'
+
+const setupStore = async (options: SetupStoreOptions = {}) => {
   vi.resetModules()
 
   const agentSessionPresenter = {
@@ -25,6 +33,21 @@ const setupStore = async () => {
     goToNewThread: vi.fn(),
     currentRoute: 'chat'
   }
+  const settings = { ...(options.initialSettings ?? {}) }
+  const configPresenter = {
+    getSetting: vi.fn(async <T>(key: string) => {
+      if (options.failGetSetting) {
+        throw new Error('failed to read setting')
+      }
+      return settings[key] as T | undefined
+    }),
+    setSetting: vi.fn(async <T>(key: string, value: T) => {
+      if (options.failSetSetting) {
+        throw new Error('failed to write setting')
+      }
+      settings[key] = value
+    })
+  }
   const listeners = new Map<string, Array<(...args: any[]) => void>>()
 
   vi.doMock('pinia', () => ({
@@ -32,7 +55,11 @@ const setupStore = async () => {
   }))
 
   vi.doMock('@/composables/usePresenter', () => ({
-    usePresenter: (name: string) => (name === 'tabPresenter' ? tabPresenter : agentSessionPresenter)
+    usePresenter: (name: string) => {
+      if (name === 'tabPresenter') return tabPresenter
+      if (name === 'configPresenter') return configPresenter
+      return agentSessionPresenter
+    }
   }))
 
   vi.doMock('@/stores/ui/pageRouter', () => ({
@@ -67,12 +94,26 @@ const setupStore = async () => {
       handler(undefined, payload)
     }
   }
-  return { store, clearStreamingState, agentSessionPresenter, pageRouter, emitIpc, SESSION_EVENTS }
+  return {
+    store,
+    settings,
+    configPresenter,
+    clearStreamingState,
+    agentSessionPresenter,
+    pageRouter,
+    emitIpc,
+    SESSION_EVENTS
+  }
 }
 
 describe('sessionStore.getFilteredGroups', () => {
   it('hides draft sessions from grouped sidebar lists', async () => {
-    const { store } = await setupStore()
+    const { store } = await setupStore({
+      initialSettings: {
+        [SIDEBAR_GROUP_MODE_KEY]: 'time'
+      }
+    })
+    await store.fetchSessions()
     const now = Date.now()
 
     store.sessions.value = [
@@ -152,6 +193,123 @@ describe('sessionStore.getFilteredGroups', () => {
     expect(groupIds).toEqual(['normal-1'])
     expect(pinnedIds).toEqual(['pinned-1'])
   })
+
+  it('uses the last path segment for Windows project labels', async () => {
+    const { store } = await setupStore()
+    const now = Date.now()
+
+    await store.fetchSessions()
+    store.sessions.value = [
+      {
+        id: 'windows-1',
+        title: 'Windows Chat',
+        agentId: 'deepchat',
+        status: 'none',
+        projectDir: 'C:\\Users\\DeepChat\\workspace',
+        providerId: 'openai',
+        modelId: 'gpt-4',
+        isPinned: false,
+        isDraft: false,
+        createdAt: now,
+        updatedAt: now
+      }
+    ]
+
+    const groups = store.getFilteredGroups(null)
+
+    expect(groups).toHaveLength(1)
+    expect(groups[0]?.label).toBe('workspace')
+  })
+})
+
+describe('sessionStore group mode preferences', () => {
+  it('falls back to project when no saved preference exists', async () => {
+    const { store } = await setupStore()
+
+    await store.fetchSessions()
+
+    expect(store.groupMode.value).toBe('project')
+  })
+
+  it('restores the saved group mode preference', async () => {
+    const { store } = await setupStore({
+      initialSettings: {
+        [SIDEBAR_GROUP_MODE_KEY]: 'time'
+      }
+    })
+
+    await store.fetchSessions()
+
+    expect(store.groupMode.value).toBe('time')
+  })
+
+  it('falls back to project when the saved preference is invalid', async () => {
+    const { store } = await setupStore({
+      initialSettings: {
+        [SIDEBAR_GROUP_MODE_KEY]: 'invalid-mode'
+      }
+    })
+
+    await store.fetchSessions()
+
+    expect(store.groupMode.value).toBe('project')
+  })
+
+  it('persists toggled group mode changes', async () => {
+    const { store, settings, configPresenter } = await setupStore()
+
+    await store.fetchSessions()
+    await store.toggleGroupMode()
+
+    expect(store.groupMode.value).toBe('time')
+    expect(configPresenter.setSetting).toHaveBeenCalledWith(SIDEBAR_GROUP_MODE_KEY, 'time')
+    expect(settings[SIDEBAR_GROUP_MODE_KEY]).toBe('time')
+  })
+
+  it('rolls back the group mode when persistence fails', async () => {
+    const { store, configPresenter } = await setupStore({
+      failSetSetting: true
+    })
+
+    await store.fetchSessions()
+    await store.toggleGroupMode()
+
+    expect(store.groupMode.value).toBe('project')
+    expect(configPresenter.setSetting).toHaveBeenCalledWith(SIDEBAR_GROUP_MODE_KEY, 'time')
+  })
+
+  it('serializes concurrent group mode writes and persists the last toggle', async () => {
+    const { store, settings, configPresenter } = await setupStore()
+    const pendingResolvers: Array<() => void> = []
+
+    await store.fetchSessions()
+    configPresenter.setSetting.mockImplementation(async <T>(key: string, value: T) => {
+      await new Promise<void>((resolve) => {
+        pendingResolvers.push(() => {
+          settings[key] = value
+          resolve()
+        })
+      })
+    })
+
+    const firstToggle = store.toggleGroupMode()
+    const secondToggle = store.toggleGroupMode()
+
+    await Promise.resolve()
+
+    expect(store.groupMode.value).toBe('project')
+    expect(configPresenter.setSetting).toHaveBeenCalledTimes(1)
+
+    pendingResolvers.shift()?.()
+    await new Promise((resolve) => setTimeout(resolve, 0))
+
+    expect(configPresenter.setSetting).toHaveBeenCalledTimes(2)
+
+    pendingResolvers.shift()?.()
+    await Promise.all([firstToggle, secondToggle])
+
+    expect(settings[SIDEBAR_GROUP_MODE_KEY]).toBe('project')
+  })
 })
 
 describe('sessionStore streaming cleanup', () => {