diff --git a/electron/main/database/core.ts b/electron/main/database/core.ts
index 4dbd198..8a3f1ef 100644
--- a/electron/main/database/core.ts
+++ b/electron/main/database/core.ts
@@ -59,7 +59,8 @@ function createDatabase(sessionId: string): Database.Database {
       group_id TEXT,
       group_avatar TEXT,
       owner_id TEXT,
-      schema_version INTEGER DEFAULT ${CURRENT_SCHEMA_VERSION}
+      schema_version INTEGER DEFAULT ${CURRENT_SCHEMA_VERSION},
+      session_gap_threshold INTEGER
     );
 
     CREATE TABLE IF NOT EXISTS member (
@@ -95,10 +96,27 @@ function createDatabase(sessionId: string): Database.Database {
       FOREIGN KEY(sender_id) REFERENCES member(id)
     );
 
+    CREATE TABLE IF NOT EXISTS chat_session (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      start_ts INTEGER NOT NULL,
+      end_ts INTEGER NOT NULL,
+      message_count INTEGER DEFAULT 0,
+      is_manual INTEGER DEFAULT 0,
+      summary TEXT
+    );
+
+    CREATE TABLE IF NOT EXISTS message_context (
+      message_id INTEGER PRIMARY KEY,
+      session_id INTEGER NOT NULL,
+      topic_id INTEGER
+    );
+
     CREATE INDEX IF NOT EXISTS idx_message_ts ON message(ts);
     CREATE INDEX IF NOT EXISTS idx_message_sender ON message(sender_id);
     CREATE INDEX IF NOT EXISTS idx_message_platform_id ON message(platform_message_id);
     CREATE INDEX IF NOT EXISTS idx_member_name_history_member_id ON member_name_history(member_id);
+    CREATE INDEX IF NOT EXISTS idx_session_time ON chat_session(start_ts, end_ts);
+    CREATE INDEX IF NOT EXISTS idx_context_session ON message_context(session_id);
   `)
 
   return db
@@ -424,7 +442,12 @@ export function checkMigrationNeeded(): {
     }
   }
 
-  return { count: needsMigrationList.length, sessionIds: needsMigrationList, lowestVersion, forceRepairIds: forceRepairList }
+  return {
+    count: needsMigrationList.length,
+    sessionIds: needsMigrationList,
+    lowestVersion,
+    forceRepairIds: forceRepairList,
+  }
 }
 
 /**
diff --git a/electron/main/database/migrations.ts b/electron/main/database/migrations.ts
index 1cba38a..3069f4e 100644
--- a/electron/main/database/migrations.ts
+++ b/electron/main/database/migrations.ts
@@ -34,7 +34,7 @@ export interface MigrationInfo {
 }
 
 /** 当前 schema 版本（最新迁移的版本号） */
-export const CURRENT_SCHEMA_VERSION = 2
+export const CURRENT_SCHEMA_VERSION = 3
 
 /**
  * 迁移脚本列表
@@ -89,6 +89,54 @@ const migrations: Migration[] = [
       }
     },
   },
+  {
+    version: 3,
+    description: '添加会话索引相关表（chat_session、message_context）和 session_gap_threshold 字段',
+    userMessage: '支持会话时间轴浏览和 AI 增强分析功能',
+    up: (db) => {
+      // 创建 chat_session 会话表
+      db.exec(`
+        CREATE TABLE IF NOT EXISTS chat_session (
+          id INTEGER PRIMARY KEY AUTOINCREMENT,
+          start_ts INTEGER NOT NULL,
+          end_ts INTEGER NOT NULL,
+          message_count INTEGER DEFAULT 0,
+          is_manual INTEGER DEFAULT 0,
+          summary TEXT
+        )
+      `)
+
+      // 创建会话时间索引
+      try {
+        db.exec('CREATE INDEX IF NOT EXISTS idx_session_time ON chat_session(start_ts, end_ts)')
+      } catch {
+        // 索引可能已存在
+      }
+
+      // 创建 message_context 消息上下文表（预留 topic_id）
+      db.exec(`
+        CREATE TABLE IF NOT EXISTS message_context (
+          message_id INTEGER PRIMARY KEY,
+          session_id INTEGER NOT NULL,
+          topic_id INTEGER
+        )
+      `)
+
+      // 创建 session_id 索引
+      try {
+        db.exec('CREATE INDEX IF NOT EXISTS idx_context_session ON message_context(session_id)')
+      } catch {
+        // 索引可能已存在
+      }
+
+      // 检查 meta 表是否已有 session_gap_threshold 列
+      const tableInfo = db.prepare('PRAGMA table_info(meta)').all() as Array<{ name: string }>
+      const hasGapThresholdColumn = tableInfo.some((col) => col.name === 'session_gap_threshold')
+      if (!hasGapThresholdColumn) {
+        db.exec('ALTER TABLE meta ADD COLUMN session_gap_threshold INTEGER')
+      }
+    },
+  },
 ]
 
 /**
@@ -149,9 +197,7 @@ export function migrateDatabase(db: Database.Database, forceRepair = false): boo
 
   // 获取需要执行的迁移
   // 如果是强制修复，从 version 0 开始执行所有迁移
-  const pendingMigrations = forceRepair
-    ? migrations
-    : migrations.filter((m) => m.version > currentVersion)
+  const pendingMigrations = forceRepair ? migrations : migrations.filter((m) => m.version > currentVersion)
 
   if (pendingMigrations.length === 0) {
     return false
diff --git a/electron/main/ipc/chat.ts b/electron/main/ipc/chat.ts
index 8fd31a9..e4aa0fa 100644
--- a/electron/main/ipc/chat.ts
+++ b/electron/main/ipc/chat.ts
@@ -623,4 +623,80 @@ export function registerChatHandlers(ctx: IpcContext): void {
       return []
     }
   })
+
+  // ==================== 会话索引 ====================
+
+  /**
+   * 生成会话索引
+   */
+  ipcMain.handle('session:generate', async (_, sessionId: string, gapThreshold?: number) => {
+    try {
+      return await worker.generateSessions(sessionId, gapThreshold)
+    } catch (error) {
+      console.error('生成会话索引失败：', error)
+      throw error
+    }
+  })
+
+  /**
+   * 检查是否已生成会话索引
+   */
+  ipcMain.handle('session:hasIndex', async (_, sessionId: string) => {
+    try {
+      return await worker.hasSessionIndex(sessionId)
+    } catch (error) {
+      console.error('检查会话索引失败：', error)
+      return false
+    }
+  })
+
+  /**
+   * 获取会话索引统计信息
+   */
+  ipcMain.handle('session:getStats', async (_, sessionId: string) => {
+    try {
+      return await worker.getSessionStats(sessionId)
+    } catch (error) {
+      console.error('获取会话统计失败：', error)
+      return { sessionCount: 0, hasIndex: false, gapThreshold: 1800 }
+    }
+  })
+
+  /**
+   * 清空会话索引
+   */
+  ipcMain.handle('session:clear', async (_, sessionId: string) => {
+    try {
+      await worker.clearSessions(sessionId)
+      return true
+    } catch (error) {
+      console.error('清空会话索引失败：', error)
+      return false
+    }
+  })
+
+  /**
+   * 更新会话切分阈值
+   */
+  ipcMain.handle('session:updateGapThreshold', async (_, sessionId: string, gapThreshold: number | null) => {
+    try {
+      await worker.updateSessionGapThreshold(sessionId, gapThreshold)
+      return true
+    } catch (error) {
+      console.error('更新阈值失败：', error)
+      return false
+    }
+  })
+
+  /**
+   * 获取会话列表（用于时间线导航）
+   */
+  ipcMain.handle('session:getSessions', async (_, sessionId: string) => {
+    try {
+      return await worker.getSessions(sessionId)
+    } catch (error) {
+      console.error('获取会话列表失败：', error)
+      return []
+    }
+  })
 }
diff --git a/electron/main/worker/dbWorker.ts b/electron/main/worker/dbWorker.ts
index 00269a4..1858709 100644
--- a/electron/main/worker/dbWorker.ts
+++ b/electron/main/worker/dbWorker.ts
@@ -47,6 +47,13 @@ import {
   // SQL 实验室
   executeRawSQL,
   getSchema,
+  // 会话索引
+  generateSessions,
+  clearSessions,
+  hasSessionIndex,
+  getSessionStats,
+  updateSessionGapThreshold,
+  getSessions,
 } from './query'
 import { streamImport, streamParseFileInfo } from './import'
 
@@ -115,6 +122,14 @@ const syncHandlers: Record<string, (payload: any) => any> = {
   // SQL 实验室
   executeRawSQL: (p) => executeRawSQL(p.sessionId, p.sql),
   getSchema: (p) => getSchema(p.sessionId),
+
+  // 会话索引
+  generateSessions: (p) => generateSessions(p.sessionId, p.gapThreshold),
+  clearSessions: (p) => clearSessions(p.sessionId),
+  hasSessionIndex: (p) => hasSessionIndex(p.sessionId),
+  getSessionStats: (p) => getSessionStats(p.sessionId),
+  updateSessionGapThreshold: (p) => updateSessionGapThreshold(p.sessionId, p.gapThreshold),
+  getSessions: (p) => getSessions(p.sessionId),
 }
 
 // 异步消息处理器（流式操作）
diff --git a/electron/main/worker/import/streamImport.ts b/electron/main/worker/import/streamImport.ts
index bbd55c6..c3db48a 100644
--- a/electron/main/worker/import/streamImport.ts
+++ b/electron/main/worker/import/streamImport.ts
@@ -150,7 +150,8 @@ function createDatabaseWithoutIndexes(sessionId: string): Database.Database {
       group_id TEXT,
       group_avatar TEXT,
       owner_id TEXT,
-      schema_version INTEGER DEFAULT 2
+      schema_version INTEGER DEFAULT 3,
+      session_gap_threshold INTEGER
     );
 
     CREATE TABLE IF NOT EXISTS member (
@@ -185,6 +186,21 @@ function createDatabaseWithoutIndexes(sessionId: string): Database.Database {
       platform_message_id TEXT DEFAULT NULL,
       FOREIGN KEY(sender_id) REFERENCES member(id)
     );
+
+    CREATE TABLE IF NOT EXISTS chat_session (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      start_ts INTEGER NOT NULL,
+      end_ts INTEGER NOT NULL,
+      message_count INTEGER DEFAULT 0,
+      is_manual INTEGER DEFAULT 0,
+      summary TEXT
+    );
+
+    CREATE TABLE IF NOT EXISTS message_context (
+      message_id INTEGER PRIMARY KEY,
+      session_id INTEGER NOT NULL,
+      topic_id INTEGER
+    );
   `)
 
   return db
@@ -199,6 +215,8 @@ function createIndexes(db: Database.Database): void {
     CREATE INDEX IF NOT EXISTS idx_message_sender ON message(sender_id);
     CREATE INDEX IF NOT EXISTS idx_message_platform_id ON message(platform_message_id);
     CREATE INDEX IF NOT EXISTS idx_member_name_history_member_id ON member_name_history(member_id);
+    CREATE INDEX IF NOT EXISTS idx_session_time ON chat_session(start_ts, end_ts);
+    CREATE INDEX IF NOT EXISTS idx_context_session ON message_context(session_id);
   `)
 }
 
@@ -440,7 +458,13 @@ export async function streamImport(filePath: string, requestId: string): Promise
           let t0 = Date.now()
           if (!memberIdMap.has(msg.senderPlatformId)) {
             // 消息中没有头像和角色信息，设为默认值
-            insertMember.run(msg.senderPlatformId, msg.senderAccountName || null, msg.senderGroupNickname || null, null, '[]')
+            insertMember.run(
+              msg.senderPlatformId,
+              msg.senderAccountName || null,
+              msg.senderGroupNickname || null,
+              null,
+              '[]'
+            )
             const row = getMemberId.get(msg.senderPlatformId) as { id: number } | undefined
             if (row) {
               memberIdMap.set(msg.senderPlatformId, row.id)
diff --git a/electron/main/worker/query/index.ts b/electron/main/worker/query/index.ts
index aa13362..6c6582b 100644
--- a/electron/main/worker/query/index.ts
+++ b/electron/main/worker/query/index.ts
@@ -53,3 +53,15 @@ export type { MessageResult, PaginatedMessages, MessagesWithTotal } from './mess
 // SQL 实验室
 export { executeRawSQL, getSchema } from './sql'
 export type { SQLResult, TableSchema } from './sql'
+
+// 会话索引
+export {
+  generateSessions,
+  clearSessions,
+  hasSessionIndex,
+  getSessionStats,
+  updateSessionGapThreshold,
+  getSessions,
+  DEFAULT_SESSION_GAP_THRESHOLD,
+} from './session'
+export type { ChatSessionItem } from './session'
diff --git a/electron/main/worker/query/session.ts b/electron/main/worker/query/session.ts
new file mode 100644
index 0000000..7a0b6f0
--- /dev/null
+++ b/electron/main/worker/query/session.ts
@@ -0,0 +1,342 @@
+/**
+ * 会话索引模块
+ * 提供基于时间间隔的会话切分算法
+ */
+
+import Database from 'better-sqlite3'
+import { getDbPath, closeDatabase } from '../core'
+
+/** 默认会话切分阈值：30分钟（秒） */
+export const DEFAULT_SESSION_GAP_THRESHOLD = 1800
+
+/**
+ * 打开数据库（可写模式，不使用缓存）
+ * 会话索引需要写入数据
+ */
+function openWritableDatabase(sessionId: string): Database.Database | null {
+  const dbPath = getDbPath(sessionId)
+  try {
+    const db = new Database(dbPath)
+    db.pragma('journal_mode = WAL')
+    return db
+  } catch {
+    return null
+  }
+}
+
+/**
+ * 打开数据库（只读模式，不使用缓存）
+ */
+function openReadonlyDatabase(sessionId: string): Database.Database | null {
+  const dbPath = getDbPath(sessionId)
+  try {
+    const db = new Database(dbPath, { readonly: true })
+    db.pragma('journal_mode = WAL')
+    return db
+  } catch {
+    return null
+  }
+}
+
+/**
+ * 生成会话索引
+ * 使用 Gap-based 算法，根据消息时间间隔自动切分会话
+ *
+ * @param sessionId 数据库会话ID
+ * @param gapThreshold 时间间隔阈值（秒），默认 1800（30分钟）
+ * @param onProgress 进度回调
+ * @returns 生成的会话数量
+ */
+export function generateSessions(
+  sessionId: string,
+  gapThreshold: number = DEFAULT_SESSION_GAP_THRESHOLD,
+  onProgress?: (current: number, total: number) => void
+): number {
+  // 先关闭缓存的只读连接
+  closeDatabase(sessionId)
+
+  const db = openWritableDatabase(sessionId)
+  if (!db) {
+    throw new Error(`无法打开数据库: ${sessionId}`)
+  }
+
+  try {
+    // 获取消息总数
+    const countResult = db.prepare('SELECT COUNT(*) as count FROM message').get() as { count: number }
+    const totalMessages = countResult.count
+
+    if (totalMessages === 0) {
+      return 0
+    }
+
+    // 清空已有的会话数据
+    clearSessionsInternal(db)
+
+    // 使用窗口函数计算会话边界
+    // 步骤1：为每条消息计算与前一条的时间差，标记新会话起点
+    const sessionMarkSQL = `
+      WITH message_ordered AS (
+        SELECT
+          id,
+          ts,
+          LAG(ts) OVER (ORDER BY ts, id) AS prev_ts
+        FROM message
+      ),
+      session_marks AS (
+        SELECT
+          id,
+          ts,
+          CASE
+            WHEN prev_ts IS NULL OR (ts - prev_ts) > ? THEN 1
+            ELSE 0
+          END AS is_new_session
+        FROM message_ordered
+      ),
+      session_ids AS (
+        SELECT
+          id,
+          ts,
+          SUM(is_new_session) OVER (ORDER BY ts, id) AS session_num
+        FROM session_marks
+      )
+      SELECT id, ts, session_num FROM session_ids
+    `
+
+    const messages = db.prepare(sessionMarkSQL).all(gapThreshold) as Array<{
+      id: number
+      ts: number
+      session_num: number
+    }>
+
+    if (messages.length === 0) {
+      return 0
+    }
+
+    // 步骤2：计算每个会话的统计信息
+    const sessionMap = new Map<number, { startTs: number; endTs: number; messageIds: number[] }>()
+
+    for (const msg of messages) {
+      const session = sessionMap.get(msg.session_num)
+      if (!session) {
+        sessionMap.set(msg.session_num, {
+          startTs: msg.ts,
+          endTs: msg.ts,
+          messageIds: [msg.id],
+        })
+      } else {
+        session.endTs = msg.ts
+        session.messageIds.push(msg.id)
+      }
+    }
+
+    // 步骤3：批量写入 chat_session 和 message_context 表
+    const insertSession = db.prepare(`
+      INSERT INTO chat_session (start_ts, end_ts, message_count, is_manual, summary)
+      VALUES (?, ?, ?, 0, NULL)
+    `)
+
+    const insertContext = db.prepare(`
+      INSERT INTO message_context (message_id, session_id, topic_id)
+      VALUES (?, ?, NULL)
+    `)
+
+    // 开始事务
+    const transaction = db.transaction(() => {
+      let processedCount = 0
+      const totalSessions = sessionMap.size
+
+      for (const [, sessionData] of sessionMap) {
+        // 插入会话记录
+        const result = insertSession.run(sessionData.startTs, sessionData.endTs, sessionData.messageIds.length)
+        const newSessionId = result.lastInsertRowid as number
+
+        // 批量插入消息上下文
+        for (const messageId of sessionData.messageIds) {
+          insertContext.run(messageId, newSessionId)
+        }
+
+        processedCount++
+        if (onProgress && processedCount % 100 === 0) {
+          onProgress(processedCount, totalSessions)
+        }
+      }
+
+      return totalSessions
+    })
+
+    const sessionCount = transaction()
+
+    // 最终进度回调
+    if (onProgress) {
+      onProgress(sessionCount, sessionCount)
+    }
+
+    return sessionCount
+  } finally {
+    db.close()
+  }
+}
+
+/**
+ * 清空会话索引数据
+ * @param sessionId 数据库会话ID
+ */
+export function clearSessions(sessionId: string): void {
+  // 先关闭缓存的只读连接
+  closeDatabase(sessionId)
+
+  const db = openWritableDatabase(sessionId)
+  if (!db) {
+    throw new Error(`无法打开数据库: ${sessionId}`)
+  }
+
+  try {
+    clearSessionsInternal(db)
+  } finally {
+    db.close()
+  }
+}
+
+/**
+ * 内部清空会话数据函数
+ */
+function clearSessionsInternal(db: Database.Database): void {
+  db.exec('DELETE FROM message_context')
+  db.exec('DELETE FROM chat_session')
+}
+
+/**
+ * 检查是否已生成会话索引
+ * @param sessionId 数据库会话ID
+ * @returns 是否有会话索引
+ */
+export function hasSessionIndex(sessionId: string): boolean {
+  const db = openReadonlyDatabase(sessionId)
+  if (!db) {
+    return false
+  }
+
+  try {
+    // 检查 chat_session 表是否存在且有数据
+    const result = db.prepare('SELECT COUNT(*) as count FROM chat_session').get() as { count: number }
+    return result.count > 0
+  } catch {
+    // 表可能不存在
+    return false
+  } finally {
+    db.close()
+  }
+}
+
+/**
+ * 获取会话索引统计信息
+ * @param sessionId 数据库会话ID
+ */
+export function getSessionStats(sessionId: string): {
+  sessionCount: number
+  hasIndex: boolean
+  gapThreshold: number
+} {
+  const db = openReadonlyDatabase(sessionId)
+  if (!db) {
+    return { sessionCount: 0, hasIndex: false, gapThreshold: DEFAULT_SESSION_GAP_THRESHOLD }
+  }
+
+  try {
+    // 获取会话数量
+    let sessionCount = 0
+    try {
+      const countResult = db.prepare('SELECT COUNT(*) as count FROM chat_session').get() as { count: number }
+      sessionCount = countResult.count
+    } catch {
+      // 表可能不存在
+    }
+
+    // 获取配置的阈值
+    let gapThreshold = DEFAULT_SESSION_GAP_THRESHOLD
+    try {
+      const metaResult = db.prepare('SELECT session_gap_threshold FROM meta LIMIT 1').get() as
+        | {
+            session_gap_threshold: number | null
+          }
+        | undefined
+      if (metaResult?.session_gap_threshold) {
+        gapThreshold = metaResult.session_gap_threshold
+      }
+    } catch {
+      // 字段可能不存在
+    }
+
+    return {
+      sessionCount,
+      hasIndex: sessionCount > 0,
+      gapThreshold,
+    }
+  } finally {
+    db.close()
+  }
+}
+
+/**
+ * 更新单个聊天的会话切分阈值
+ * @param sessionId 数据库会话ID
+ * @param gapThreshold 阈值（秒），null 表示使用全局配置
+ */
+export function updateSessionGapThreshold(sessionId: string, gapThreshold: number | null): void {
+  // 先关闭缓存的只读连接
+  closeDatabase(sessionId)
+
+  const db = openWritableDatabase(sessionId)
+  if (!db) {
+    throw new Error(`无法打开数据库: ${sessionId}`)
+  }
+
+  try {
+    db.prepare('UPDATE meta SET session_gap_threshold = ?').run(gapThreshold)
+  } finally {
+    db.close()
+  }
+}
+
+/**
+ * 会话列表项类型
+ */
+export interface ChatSessionItem {
+  id: number
+  startTs: number
+  endTs: number
+  messageCount: number
+  firstMessageId: number
+}
+
+/**
+ * 获取会话列表（用于时间线导航）
+ * @param sessionId 数据库会话ID
+ * @returns 会话列表，按时间排序
+ */
+export function getSessions(sessionId: string): ChatSessionItem[] {
+  const db = openReadonlyDatabase(sessionId)
+  if (!db) {
+    return []
+  }
+
+  try {
+    // 查询会话列表，同时获取每个会话的首条消息 ID
+    const sql = `
+      SELECT
+        cs.id,
+        cs.start_ts as startTs,
+        cs.end_ts as endTs,
+        cs.message_count as messageCount,
+        (SELECT mc.message_id FROM message_context mc WHERE mc.session_id = cs.id ORDER BY mc.message_id LIMIT 1) as firstMessageId
+      FROM chat_session cs
+      ORDER BY cs.start_ts ASC
+    `
+    const sessions = db.prepare(sql).all() as ChatSessionItem[]
+    return sessions
+  } catch {
+    return []
+  } finally {
+    db.close()
+  }
+}
diff --git a/electron/main/worker/workerManager.ts b/electron/main/worker/workerManager.ts
index 502cd09..b9c26d8 100644
--- a/electron/main/worker/workerManager.ts
+++ b/electron/main/worker/workerManager.ts
@@ -494,3 +494,66 @@ export async function executeRawSQL(sessionId: string, sql: string): Promise<SQL
 export async function getSchema(sessionId: string): Promise<TableSchema[]> {
   return sendToWorker('getSchema', { sessionId })
 }
+
+// ==================== 会话索引 API ====================
+
+export interface SessionStats {
+  sessionCount: number
+  hasIndex: boolean
+  gapThreshold: number
+}
+
+/**
+ * 生成会话索引
+ * @param sessionId 数据库会话ID
+ * @param gapThreshold 时间间隔阈值（秒）
+ */
+export async function generateSessions(sessionId: string, gapThreshold?: number): Promise<number> {
+  return sendToWorker('generateSessions', { sessionId, gapThreshold })
+}
+
+/**
+ * 清空会话索引
+ */
+export async function clearSessions(sessionId: string): Promise<void> {
+  return sendToWorker('clearSessions', { sessionId })
+}
+
+/**
+ * 检查是否已生成会话索引
+ */
+export async function hasSessionIndex(sessionId: string): Promise<boolean> {
+  return sendToWorker('hasSessionIndex', { sessionId })
+}
+
+/**
+ * 获取会话索引统计信息
+ */
+export async function getSessionStats(sessionId: string): Promise<SessionStats> {
+  return sendToWorker('getSessionStats', { sessionId })
+}
+
+/**
+ * 更新单个聊天的会话切分阈值
+ */
+export async function updateSessionGapThreshold(sessionId: string, gapThreshold: number | null): Promise<void> {
+  return sendToWorker('updateSessionGapThreshold', { sessionId, gapThreshold })
+}
+
+/**
+ * 会话列表项类型
+ */
+export interface ChatSessionItem {
+  id: number
+  startTs: number
+  endTs: number
+  messageCount: number
+  firstMessageId: number
+}
+
+/**
+ * 获取会话列表（用于时间线导航）
+ */
+export async function getSessions(sessionId: string): Promise<ChatSessionItem[]> {
+  return sendToWorker('getSessions', { sessionId })
+}
diff --git a/electron/preload/index.d.ts b/electron/preload/index.d.ts
index abd6232..437a6f1 100644
--- a/electron/preload/index.d.ts
+++ b/electron/preload/index.d.ts
@@ -440,6 +440,30 @@ interface NetworkApi {
   testProxyConnection: (proxyUrl: string) => Promise<{ success: boolean; error?: string }>
 }
 
+// Session Index API 类型 - 会话索引功能
+interface SessionStats {
+  sessionCount: number
+  hasIndex: boolean
+  gapThreshold: number
+}
+
+interface ChatSessionItem {
+  id: number
+  startTs: number
+  endTs: number
+  messageCount: number
+  firstMessageId: number
+}
+
+interface SessionApi {
+  generate: (sessionId: string, gapThreshold?: number) => Promise<number>
+  hasIndex: (sessionId: string) => Promise<boolean>
+  getStats: (sessionId: string) => Promise<SessionStats>
+  clear: (sessionId: string) => Promise<boolean>
+  updateGapThreshold: (sessionId: string, gapThreshold: number | null) => Promise<boolean>
+  getSessions: (sessionId: string) => Promise<ChatSessionItem[]>
+}
+
 declare global {
   interface Window {
     electron: ElectronAPI
@@ -451,6 +475,7 @@ declare global {
     agentApi: AgentApi
     cacheApi: CacheApi
     networkApi: NetworkApi
+    sessionApi: SessionApi
   }
 }
 
diff --git a/electron/preload/index.ts b/electron/preload/index.ts
index 35f63ed..7c8e197 100644
--- a/electron/preload/index.ts
+++ b/electron/preload/index.ts
@@ -1051,6 +1051,68 @@ const cacheApi = {
   },
 }
 
+// Session Index API - 会话索引功能
+interface SessionStats {
+  sessionCount: number
+  hasIndex: boolean
+  gapThreshold: number
+}
+
+interface ChatSessionItem {
+  id: number
+  startTs: number
+  endTs: number
+  messageCount: number
+  firstMessageId: number
+}
+
+const sessionApi = {
+  /**
+   * 生成会话索引
+   * @param sessionId 数据库会话ID
+   * @param gapThreshold 时间间隔阈值（秒）
+   * @returns 生成的会话数量
+   */
+  generate: (sessionId: string, gapThreshold?: number): Promise<number> => {
+    return ipcRenderer.invoke('session:generate', sessionId, gapThreshold)
+  },
+
+  /**
+   * 检查是否已生成会话索引
+   */
+  hasIndex: (sessionId: string): Promise<boolean> => {
+    return ipcRenderer.invoke('session:hasIndex', sessionId)
+  },
+
+  /**
+   * 获取会话索引统计信息
+   */
+  getStats: (sessionId: string): Promise<SessionStats> => {
+    return ipcRenderer.invoke('session:getStats', sessionId)
+  },
+
+  /**
+   * 清空会话索引
+   */
+  clear: (sessionId: string): Promise<boolean> => {
+    return ipcRenderer.invoke('session:clear', sessionId)
+  },
+
+  /**
+   * 更新会话切分阈值
+   */
+  updateGapThreshold: (sessionId: string, gapThreshold: number | null): Promise<boolean> => {
+    return ipcRenderer.invoke('session:updateGapThreshold', sessionId, gapThreshold)
+  },
+
+  /**
+   * 获取会话列表（用于时间线导航）
+   */
+  getSessions: (sessionId: string): Promise<ChatSessionItem[]> => {
+    return ipcRenderer.invoke('session:getSessions', sessionId)
+  },
+}
+
 // 扩展 api，添加 dialog、clipboard 和应用功能
 const extendedApi = {
   ...api,
@@ -1122,6 +1184,7 @@ if (process.contextIsolated) {
     contextBridge.exposeInMainWorld('agentApi', agentApi)
     contextBridge.exposeInMainWorld('cacheApi', cacheApi)
     contextBridge.exposeInMainWorld('networkApi', networkApi)
+    contextBridge.exposeInMainWorld('sessionApi', sessionApi)
   } catch (error) {
     console.error(error)
   }
@@ -1144,4 +1207,6 @@ if (process.contextIsolated) {
   window.cacheApi = cacheApi
   // @ts-ignore (define in dts)
   window.networkApi = networkApi
+  // @ts-ignore (define in dts)
+  window.sessionApi = sessionApi
 }
diff --git a/src/components/analysis/SessionIndexModal.vue b/src/components/analysis/SessionIndexModal.vue
new file mode 100644
index 0000000..dea472a
--- /dev/null
+++ b/src/components/analysis/SessionIndexModal.vue
@@ -0,0 +1,298 @@
+<script setup lang="ts">
+/**
+ * 会话索引生成弹窗组件
+ * 自动检测索引状态，未生成时通过 v-model 自动弹出
+ * 使用 v-model 控制显示状态
+ */
+import { ref, watch, computed, onMounted } from 'vue'
+import { useI18n } from 'vue-i18n'
+
+const props = defineProps<{
+  sessionId: string
+  /** 弹窗打开状态（v-model） */
+  modelValue?: boolean
+}>()
+
+const emit = defineEmits<{
+  /** 更新 v-model */
+  (e: 'update:modelValue', value: boolean): void
+  /** 生成完成 */
+  (e: 'generated', sessionCount: number): void
+}>()
+
+const { t } = useI18n()
+
+// 状态
+const hasIndex = ref(false)
+const sessionCount = ref(0)
+const isGenerating = ref(false)
+const isLoading = ref(true)
+// 是否是强制模式（未生成索引时自动弹出的情况）
+const forceMode = ref(false)
+
+// 是否打开（双向绑定）
+const isOpen = computed({
+  get: () => props.modelValue ?? false,
+  set: (value) => emit('update:modelValue', value),
+})
+
+// 是否可以关闭弹窗
+const canClose = computed(() => {
+  // 强制模式下不允许关闭
+  return !forceMode.value
+})
+
+// 检查会话索引状态并自动弹出
+async function checkAndAutoOpen() {
+  if (!props.sessionId) return
+
+  isLoading.value = true
+  try {
+    const stats = await window.sessionApi.getStats(props.sessionId)
+    hasIndex.value = stats.hasIndex
+    sessionCount.value = stats.sessionCount
+
+    // 如果未生成索引，自动弹出（强制模式）
+    if (!hasIndex.value) {
+      forceMode.value = true
+      isOpen.value = true
+    }
+  } catch (error) {
+    console.error('检查会话索引失败:', error)
+  } finally {
+    isLoading.value = false
+  }
+}
+
+// 刷新状态（不自动弹出，用于手动打开时）
+async function refreshStatus() {
+  if (!props.sessionId) return
+
+  isLoading.value = true
+  try {
+    const stats = await window.sessionApi.getStats(props.sessionId)
+    hasIndex.value = stats.hasIndex
+    sessionCount.value = stats.sessionCount
+  } catch (error) {
+    console.error('检查会话索引失败:', error)
+  } finally {
+    isLoading.value = false
+  }
+}
+
+// 生成会话索引
+async function generateSessionIndex() {
+  if (!props.sessionId) return
+
+  isGenerating.value = true
+  try {
+    // 从 localStorage 获取全局阈值配置
+    const savedThreshold = localStorage.getItem('sessionGapThreshold')
+    const gapThreshold = savedThreshold ? parseInt(savedThreshold, 10) : 1800 // 默认30分钟
+
+    const count = await window.sessionApi.generate(props.sessionId, gapThreshold)
+    hasIndex.value = true
+    sessionCount.value = count
+    emit('generated', count)
+
+    // 生成完成后自动关闭
+    forceMode.value = false
+    isOpen.value = false
+  } catch (error) {
+    console.error('生成会话索引失败:', error)
+  } finally {
+    isGenerating.value = false
+  }
+}
+
+// 关闭弹窗
+function close() {
+  if (!canClose.value) return
+  isOpen.value = false
+}
+
+// 处理弹窗状态变化
+function handleOpenChange(value: boolean) {
+  if (!value && !canClose.value) {
+    // 强制模式下不允许关闭
+    return
+  }
+
+  isOpen.value = value
+
+  // 手动打开时（非强制模式），刷新状态
+  if (value && !forceMode.value) {
+    refreshStatus()
+  }
+}
+
+// sessionId 变化时重新检查并自动弹出
+watch(
+  () => props.sessionId,
+  () => {
+    checkAndAutoOpen()
+  }
+)
+
+// 组件挂载时检查
+onMounted(() => {
+  checkAndAutoOpen()
+})
+</script>
+
+<template>
+  <UModal :open="isOpen" @update:open="handleOpenChange" :dismissible="canClose">
+    <template #content>
+      <div class="p-6">
+        <!-- 头部 -->
+        <div class="mb-4 flex items-center justify-between">
+          <div class="flex items-center gap-2">
+            <div class="flex h-10 w-10 items-center justify-center rounded-full bg-blue-100 dark:bg-blue-900/30">
+              <UIcon name="i-heroicons-clock" class="h-5 w-5 text-blue-600 dark:text-blue-400" />
+            </div>
+            <div>
+              <h3 class="text-lg font-semibold text-gray-900 dark:text-white">
+                {{ t('sessionIndex.title') }}
+              </h3>
+              <p class="text-sm text-gray-500 dark:text-gray-400">
+                {{ t('sessionIndex.subtitle') }}
+              </p>
+            </div>
+          </div>
+          <UButton
+            v-if="canClose"
+            icon="i-heroicons-x-mark"
+            color="neutral"
+            variant="ghost"
+            size="sm"
+            @click="close"
+          />
+        </div>
+
+        <!-- 加载中 -->
+        <div v-if="isLoading" class="flex items-center justify-center py-8">
+          <UIcon name="i-heroicons-arrow-path" class="h-6 w-6 animate-spin text-gray-400" />
+        </div>
+
+        <!-- 内容 -->
+        <template v-else>
+          <!-- 未生成索引 -->
+          <div v-if="!hasIndex" class="space-y-4">
+            <div class="rounded-lg border border-amber-200 bg-amber-50 p-4 dark:border-amber-800/50 dark:bg-amber-900/20">
+              <div class="flex gap-3">
+                <UIcon name="i-heroicons-exclamation-triangle" class="h-5 w-5 shrink-0 text-amber-500" />
+                <div>
+                  <p class="text-sm font-medium text-amber-800 dark:text-amber-200">
+                    {{ t('sessionIndex.notGenerated') }}
+                  </p>
+                  <p class="mt-1 text-sm text-amber-700 dark:text-amber-300">
+                    {{ t('sessionIndex.notGeneratedHint') }}
+                  </p>
+                </div>
+              </div>
+            </div>
+
+            <div class="rounded-lg bg-gray-50 p-4 dark:bg-gray-800/50">
+              <h4 class="mb-2 text-sm font-medium text-gray-700 dark:text-gray-300">
+                {{ t('sessionIndex.whatIsIt') }}
+              </h4>
+              <ul class="space-y-1 text-sm text-gray-600 dark:text-gray-400">
+                <li class="flex items-start gap-2">
+                  <UIcon name="i-heroicons-check" class="mt-0.5 h-4 w-4 shrink-0 text-green-500" />
+                  {{ t('sessionIndex.benefit1') }}
+                </li>
+                <li class="flex items-start gap-2">
+                  <UIcon name="i-heroicons-check" class="mt-0.5 h-4 w-4 shrink-0 text-green-500" />
+                  {{ t('sessionIndex.benefit2') }}
+                </li>
+                <li class="flex items-start gap-2">
+                  <UIcon name="i-heroicons-check" class="mt-0.5 h-4 w-4 shrink-0 text-green-500" />
+                  {{ t('sessionIndex.benefit3') }}
+                </li>
+              </ul>
+            </div>
+          </div>
+
+          <!-- 已生成索引 -->
+          <div v-else class="space-y-4">
+            <div class="rounded-lg border border-green-200 bg-green-50 p-4 dark:border-green-800/50 dark:bg-green-900/20">
+              <div class="flex gap-3">
+                <UIcon name="i-heroicons-check-circle" class="h-5 w-5 shrink-0 text-green-500" />
+                <div>
+                  <p class="text-sm font-medium text-green-800 dark:text-green-200">
+                    {{ t('sessionIndex.generated') }}
+                  </p>
+                  <p class="mt-1 text-sm text-green-700 dark:text-green-300">
+                    {{ t('sessionIndex.sessionCount', { count: sessionCount }) }}
+                  </p>
+                </div>
+              </div>
+            </div>
+
+            <p class="text-sm text-gray-500 dark:text-gray-400">
+              {{ t('sessionIndex.regenerateHint') }}
+            </p>
+          </div>
+        </template>
+
+        <!-- 操作按钮 -->
+        <div class="mt-6 flex justify-end gap-2">
+          <UButton v-if="canClose" variant="ghost" @click="close">
+            {{ t('sessionIndex.cancel') }}
+          </UButton>
+          <UButton
+            color="primary"
+            :loading="isGenerating"
+            @click="generateSessionIndex"
+          >
+            <UIcon v-if="!isGenerating" :name="hasIndex ? 'i-heroicons-arrow-path' : 'i-heroicons-sparkles'" class="mr-1 h-4 w-4" />
+            {{ isGenerating ? t('sessionIndex.generating') : (hasIndex ? t('sessionIndex.regenerate') : t('sessionIndex.generate')) }}
+          </UButton>
+        </div>
+      </div>
+    </template>
+  </UModal>
+</template>
+
+<i18n>
+{
+  "zh-CN": {
+    "sessionIndex": {
+      "title": "会话索引",
+      "subtitle": "用于聊天记录的时间线导航",
+      "notGenerated": "尚未生成会话索引",
+      "notGeneratedHint": "生成会话索引后，您可以在聊天记录查看器中使用时间线快速导航到不同的会话。",
+      "whatIsIt": "会话索引的作用：",
+      "benefit1": "根据消息时间间隔自动识别会话边界",
+      "benefit2": "在聊天记录查看器中提供时间线导航",
+      "benefit3": "为 AI 分析提供对话上下文理解能力",
+      "generated": "会话索引已生成",
+      "sessionCount": "共识别出 {count} 个会话",
+      "regenerateHint": "如果您调整了会话间隔阈值，可以重新生成索引。",
+      "generate": "生成索引",
+      "regenerate": "重新生成",
+      "generating": "生成中...",
+      "cancel": "取消"
+    }
+  },
+  "en-US": {
+    "sessionIndex": {
+      "title": "Session Index",
+      "subtitle": "For timeline navigation in chat records",
+      "notGenerated": "Session index not generated",
+      "notGeneratedHint": "After generating session index, you can use timeline navigation in the chat record viewer to quickly jump to different sessions.",
+      "whatIsIt": "What session index does:",
+      "benefit1": "Identify conversation boundaries based on message time gaps",
+      "benefit2": "Provide timeline navigation in chat record viewer",
+      "benefit3": "Enable AI analysis to understand conversation context",
+      "generated": "Session index generated",
+      "sessionCount": "{count} sessions identified",
+      "regenerateHint": "You can regenerate the index if you've adjusted the session gap threshold.",
+      "generate": "Generate Index",
+      "regenerate": "Regenerate",
+      "generating": "Generating...",
+      "cancel": "Cancel"
+    }
+  }
+}
+</i18n>
diff --git a/src/pages/group-chat/index.vue b/src/pages/group-chat/index.vue
index a884e0e..9082842 100644
--- a/src/pages/group-chat/index.vue
+++ b/src/pages/group-chat/index.vue
@@ -14,6 +14,7 @@ import RankingTab from './components/RankingTab.vue'
 import QuotesTab from './components/QuotesTab.vue'
 import MemberTab from './components/MemberTab.vue'
 import PageHeader from '@/components/layout/PageHeader.vue'
+import SessionIndexModal from '@/components/analysis/SessionIndexModal.vue'
 import { useSessionStore } from '@/stores/session'
 import { useLayoutStore } from '@/stores/layout'
 import { isFeatureSupported, type LocaleType } from '@/i18n'
@@ -26,6 +27,9 @@ const sessionStore = useSessionStore()
 const layoutStore = useLayoutStore()
 const { currentSessionId } = storeToRefs(sessionStore)
 
+// 会话索引弹窗状态
+const showSessionIndexModal = ref(false)
+
 // 打开聊天记录查看器
 function openChatRecordViewer() {
   layoutStore.openChatRecordDrawer({})
@@ -278,6 +282,15 @@ onMounted(() => {
               @click="openChatRecordViewer"
             />
           </UTooltip>
+          <UTooltip :text="t('analysis.tooltip.sessionIndex')">
+            <UButton
+              icon="i-heroicons-clock"
+              color="neutral"
+              variant="ghost"
+              size="sm"
+              @click="showSessionIndexModal = true"
+            />
+          </UTooltip>
           <CaptureButton />
         </template>
         <!-- Tabs -->
@@ -375,6 +388,9 @@ onMounted(() => {
     <div v-else class="flex h-full items-center justify-center">
       <p class="text-gray-500">{{ t('analysis.groupChat.loadError') }}</p>
     </div>
+
+    <!-- 会话索引弹窗（内部自动检测并弹出） -->
+    <SessionIndexModal v-if="currentSessionId" v-model="showSessionIndexModal" :session-id="currentSessionId" />
   </div>
 </template>
 
diff --git a/src/pages/private-chat/index.vue b/src/pages/private-chat/index.vue
index 64208f4..9c0da3c 100644
--- a/src/pages/private-chat/index.vue
+++ b/src/pages/private-chat/index.vue
@@ -13,6 +13,7 @@ import OverviewTab from './components/OverviewTab.vue'
 import QuotesTab from './components/QuotesTab.vue'
 import MemberTab from './components/MemberTab.vue'
 import PageHeader from '@/components/layout/PageHeader.vue'
+import SessionIndexModal from '@/components/analysis/SessionIndexModal.vue'
 import { useSessionStore } from '@/stores/session'
 import { useLayoutStore } from '@/stores/layout'
 
@@ -24,6 +25,9 @@ const sessionStore = useSessionStore()
 const layoutStore = useLayoutStore()
 const { currentSessionId } = storeToRefs(sessionStore)
 
+// 会话索引弹窗状态
+const showSessionIndexModal = ref(false)
+
 // 打开聊天记录查看器
 function openChatRecordViewer() {
   layoutStore.openChatRecordDrawer({})
@@ -250,6 +254,15 @@ onMounted(() => {
               @click="openChatRecordViewer"
             />
           </UTooltip>
+          <UTooltip :text="t('analysis.tooltip.sessionIndex')">
+            <UButton
+              icon="i-heroicons-clock"
+              color="neutral"
+              variant="ghost"
+              size="sm"
+              @click="showSessionIndexModal = true"
+            />
+          </UTooltip>
           <CaptureButton />
         </template>
         <!-- Tabs -->
@@ -330,6 +343,9 @@ onMounted(() => {
     <div v-else class="flex h-full items-center justify-center">
       <p class="text-gray-500">{{ t('analysis.privateChat.loadError') }}</p>
     </div>
+
+    <!-- 会话索引弹窗（内部自动检测并弹出） -->
+    <SessionIndexModal v-if="currentSessionId" v-model="showSessionIndexModal" :session-id="currentSessionId" />
   </div>
 </template>
 
diff --git a/src/stores/session.ts b/src/stores/session.ts
index 5948c11..4cadf5f 100644
--- a/src/stores/session.ts
+++ b/src/stores/session.ts
@@ -203,6 +203,17 @@ export const useSessionStore = defineStore(
         if (importResult.success && importResult.sessionId) {
           await loadSessions()
           currentSessionId.value = importResult.sessionId
+
+          // 自动生成会话索引
+          try {
+            const savedThreshold = localStorage.getItem('sessionGapThreshold')
+            const gapThreshold = savedThreshold ? parseInt(savedThreshold, 10) : 1800 // 默认30分钟
+            await window.sessionApi.generate(importResult.sessionId, gapThreshold)
+          } catch (error) {
+            console.error('自动生成会话索引失败:', error)
+            // 不阻断导入流程，用户可以手动生成
+          }
+
           return { success: true }
         } else {
           // 传递诊断信息（如果有）
diff --git a/src/types/base.ts b/src/types/base.ts
index 3cf4e59..d4b177f 100644
--- a/src/types/base.ts
+++ b/src/types/base.ts
@@ -142,6 +142,7 @@ export interface DbMeta {
   group_id: string | null // 群ID（群聊类型有值，私聊为空）
   group_avatar: string | null // 群头像（base64 Data URL）
   owner_id: string | null // 所有者/导出者的 platformId
+  session_gap_threshold: number | null // 会话切分阈值（秒），null 表示使用全局配置
 }
 
 /**
@@ -254,3 +255,46 @@ export interface ImportResult {
   sessionId?: string // 成功时返回会话ID
   error?: string // 失败时返回错误信息
 }
+
+// ==================== 会话索引类型 ====================
+
+/**
+ * 会话（时间切分的对话段落）
+ */
+export interface ChatSession {
+  id: number // 自增ID
+  startTs: number // 会话开始时间戳（秒）
+  endTs: number // 会话结束时间戳（秒）
+  messageCount: number // 该会话包含的消息数
+  isManual: boolean // 是否用户手动合并/修改过
+  summary: string | null // AI 生成的会话简报（预留）
+}
+
+/**
+ * 消息上下文索引
+ */
+export interface MessageContext {
+  messageId: number // 关联 message.id
+  sessionId: number // 关联 chat_session.id
+  topicId: number | null // 关联 chat_topic.id（预留）
+}
+
+/**
+ * 会话索引配置
+ */
+export interface SessionConfig {
+  /** 默认切分阈值（秒） */
+  defaultGapThreshold: number
+}
+
+/**
+ * 会话统计信息
+ */
+export interface SessionStats {
+  /** 会话总数 */
+  sessionCount: number
+  /** 是否已生成会话索引 */
+  hasIndex: boolean
+  /** 当前使用的阈值（秒） */
+  gapThreshold: number
+}