diff --git a/src/config/mod.rs b/src/config/mod.rs
index d2ecf7e..f08a129 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -299,8 +299,8 @@ pub struct GatewayConfig {
     pub port: u16,
     #[serde(default)]
     pub show_tool_results: bool,
-    #[serde(default, rename = "session_ttl_hours")]
-    pub session_ttl_hours: Option<u64>,
+    #[serde(default, rename = "chat_history_ttl_hours")]
+    pub chat_history_ttl_hours: Option<u64>,
     #[serde(
         default = "default_agent_prompt_reinject_every",
         rename = "agent_prompt_reinject_every"
@@ -589,7 +589,7 @@ impl Default for GatewayConfig {
             host: default_gateway_host(),
             port: default_gateway_port(),
             show_tool_results: false,
-            session_ttl_hours: None,
+            chat_history_ttl_hours: Some(4),
             agent_prompt_reinject_every: default_agent_prompt_reinject_every(),
         }
     }
diff --git a/src/gateway/command.rs b/src/gateway/command.rs
index 49e226b..9fad8e9 100644
--- a/src/gateway/command.rs
+++ b/src/gateway/command.rs
@@ -89,6 +89,7 @@ mod tests {
             skills,
             store.clone(),
             100,
+            Some(4),
         )
         .await
         .unwrap();
@@ -116,12 +117,12 @@ mod tests {
                 .load_all_messages(&session.persistent_session_id("chat-1"))
                 .unwrap()
                 .len(),
-            2,
+            3,
         );
 
         session.ensure_chat_loaded("chat-1").unwrap();
         let history = session.get_history("chat-1").unwrap();
-        assert_eq!(history.len(), 1);
+        assert_eq!(history.len(), 2);
         assert_eq!(history[0].role, "system");
     }
 
@@ -139,6 +140,7 @@ mod tests {
             skills,
             store,
             100,
+            Some(4),
         )
         .await
         .unwrap();
@@ -155,7 +157,7 @@ mod tests {
             .unwrap();
 
         let history = session.get_history("chat-1").unwrap();
-        assert_eq!(history.len(), 1);
+        assert_eq!(history.len(), 2);
         assert_eq!(history[0].role, "system");
     }
 }
diff --git a/src/gateway/mod.rs b/src/gateway/mod.rs
index 951251f..aace5cb 100644
--- a/src/gateway/mod.rs
+++ b/src/gateway/mod.rs
@@ -60,8 +60,8 @@ impl GatewayState {
             provider_configs.insert(agent_name.clone(), config.get_provider_config(agent_name)?);
         }
 
-        // Session TTL from config (default 4 hours)
-        let session_ttl_hours = config.gateway.session_ttl_hours.unwrap_or(4);
+        // Chat history TTL from config (default 4 hours)
+        let chat_history_ttl_hours = config.gateway.chat_history_ttl_hours;
         let agent_prompt_reinject_every = config.gateway.agent_prompt_reinject_every;
         let show_tool_results = config.gateway.show_tool_results;
 
@@ -70,7 +70,6 @@ impl GatewayState {
         let bus = channel_manager.bus();
 
         let session_manager = build_session_manager_with_sender(
-            session_ttl_hours,
             agent_prompt_reinject_every,
             show_tool_results,
             config.time.timezone.clone(),
@@ -79,6 +78,7 @@ impl GatewayState {
             skills,
             Arc::new(BusSessionMessageSender::new(bus.clone())),
             std::collections::HashSet::new(),
+            chat_history_ttl_hours,
         )?;
 
         Ok(Self {
diff --git a/src/gateway/runtime.rs b/src/gateway/runtime.rs
index 6bae7c4..3652ba3 100644
--- a/src/gateway/runtime.rs
+++ b/src/gateway/runtime.rs
@@ -23,7 +23,6 @@ use super::session_lifecycle::SessionLifecycleService;
 use super::session_message_service::SessionMessageService;
 
 pub(crate) fn build_session_manager(
-    session_ttl_hours: u64,
     agent_prompt_reinject_every: u64,
     show_tool_results: bool,
     default_timezone: String,
@@ -31,9 +30,9 @@ pub(crate) fn build_session_manager(
     provider_configs: HashMap<String, LLMProviderConfig>,
     skills: Arc<SkillRuntime>,
     disabled_tools: HashSet<String>,
+    chat_history_ttl_hours: Option<u64>,
 ) -> Result<SessionManager, AgentError> {
     build_session_manager_with_sender(
-        session_ttl_hours,
         agent_prompt_reinject_every,
         show_tool_results,
         default_timezone,
@@ -42,11 +41,11 @@ pub(crate) fn build_session_manager(
         skills,
         Arc::new(NoopSessionMessageSender),
         disabled_tools,
+        chat_history_ttl_hours,
     )
 }
 
 pub(crate) fn build_session_manager_with_sender(
-    session_ttl_hours: u64,
     agent_prompt_reinject_every: u64,
     show_tool_results: bool,
     default_timezone: String,
@@ -55,6 +54,7 @@ pub(crate) fn build_session_manager_with_sender(
     skills: Arc<SkillRuntime>,
     session_message_sender: Arc<dyn SessionMessageSender>,
     disabled_tools: HashSet<String>,
+    chat_history_ttl_hours: Option<u64>,
 ) -> Result<SessionManager, AgentError> {
     let store = Arc::new(
         SessionStore::new()
@@ -97,8 +97,9 @@ pub(crate) fn build_session_manager_with_sender(
         prompt_injector,
         conversations,
         skill_events,
+        chat_history_ttl_hours,
     );
-    let lifecycle = SessionLifecycleService::new(session_ttl_hours, session_factory);
+    let lifecycle = SessionLifecycleService::new(session_factory);
     let cli_sessions = CliSessionService::new(store.clone());
     let messages = SessionMessageService::new(lifecycle.clone(), show_tool_results);
     let scheduled_tasks = ScheduledAgentTaskService::new(
diff --git a/src/gateway/session.rs b/src/gateway/session.rs
index 7b78178..ac3bb0e 100644
--- a/src/gateway/session.rs
+++ b/src/gateway/session.rs
@@ -100,6 +100,7 @@ impl Session {
         skills: Arc<SkillRuntime>,
         store: Arc<SessionStore>,
         agent_prompt_reinject_every: u64,
+        chat_history_ttl_hours: Option<u64>,
     ) -> Result<Self, AgentError> {
         let agent_factory = AgentFactory::new(tools, skills.clone());
         let conversations: Arc<dyn ConversationRepository> = store.clone();
@@ -114,6 +115,7 @@ impl Session {
             prompt_injector,
             conversations,
             skill_events,
+            chat_history_ttl_hours,
         )
         .await
     }
@@ -127,6 +129,7 @@ impl Session {
         prompt_injector: PromptInjector,
         conversations: Arc<dyn ConversationRepository>,
         skill_events: Arc<dyn SkillEventRepository>,
+        chat_history_ttl_hours: Option<u64>,
     ) -> Result<Self, AgentError> {
         Ok(Self {
             id: Uuid::new_v4(),
@@ -142,6 +145,7 @@ impl Session {
                 conversations,
                 skill_events,
                 provider_config,
+                chat_history_ttl_hours,
             ),
         })
     }
@@ -372,7 +376,6 @@ impl SessionManager {
     }
 
     pub fn new(
-        session_ttl_hours: u64,
         agent_prompt_reinject_every: u64,
         show_tool_results: bool,
         default_timezone: String,
@@ -380,9 +383,9 @@ impl SessionManager {
         provider_configs: HashMap<String, LLMProviderConfig>,
         skills: Arc<SkillRuntime>,
         disabled_tools: std::collections::HashSet<String>,
+        chat_history_ttl_hours: Option<u64>,
     ) -> Result<Self, AgentError> {
         super::runtime::build_session_manager(
-            session_ttl_hours,
             agent_prompt_reinject_every,
             show_tool_results,
             default_timezone,
@@ -390,6 +393,7 @@ impl SessionManager {
             provider_configs,
             skills,
             disabled_tools,
+            chat_history_ttl_hours,
         )
     }
 
@@ -553,6 +557,7 @@ mod tests {
             skills,
             store,
             100,
+            Some(4),
         )
         .await
         .unwrap();
@@ -599,6 +604,7 @@ mod tests {
             skills,
             store.clone(),
             100,
+            Some(4),
         )
         .await
         .unwrap();
@@ -785,7 +791,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -793,6 +798,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -831,7 +837,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -842,6 +847,7 @@ mod tests {
             ]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -899,7 +905,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -907,6 +912,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -981,7 +987,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -989,6 +994,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -1068,7 +1074,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -1076,6 +1081,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -1145,7 +1151,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -1153,6 +1158,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -1209,7 +1215,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -1217,6 +1222,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -1283,7 +1289,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -1291,6 +1296,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -1341,7 +1347,6 @@ mod tests {
         };
 
         let session_manager = SessionManager::new(
-            4,
             100,
             false,
             "Asia/Shanghai".to_string(),
@@ -1349,6 +1354,7 @@ mod tests {
             HashMap::from([("default".to_string(), provider_config)]),
             Arc::new(SkillRuntime::default()),
             HashSet::new(),
+            Some(4),
         )
         .unwrap();
 
@@ -1536,6 +1542,7 @@ mod tests {
             skills,
             store.clone(),
             100,
+            Some(4),
         )
         .await
         .unwrap();
@@ -1544,7 +1551,7 @@ mod tests {
         session.ensure_chat_loaded("chat-1").unwrap();
 
         let history = session.get_history("chat-1").unwrap();
-        assert_eq!(history.len(), 1);
+        assert_eq!(history.len(), 2);
         assert_eq!(history[0].role, "system");
         assert!(history[0].content.contains("PicoBot 代理配置"));
     }
@@ -1575,6 +1582,7 @@ mod tests {
             skills,
             store.clone(),
             100,
+            Some(4),
         )
         .await
         .unwrap();
@@ -1597,7 +1605,7 @@ mod tests {
             .iter()
             .filter(|message| message.role == "system")
             .count();
-        assert_eq!(system_messages, 2);
+        assert_eq!(system_messages, 3);
 
         let stored = store
             .get_session(&session.persistent_session_id("chat-1"))
@@ -1613,7 +1621,7 @@ mod tests {
             .iter()
             .filter(|message| message.role == "system")
             .count();
-        assert_eq!(system_messages, 2);
+        assert_eq!(system_messages, 3);
     }
 
     #[tokio::test]
@@ -1642,6 +1650,7 @@ mod tests {
             skills,
             store.clone(),
             0,
+            Some(4),
         )
         .await
         .unwrap();
@@ -1664,7 +1673,7 @@ mod tests {
             .iter()
             .filter(|message| message.role == "system")
             .count();
-        assert_eq!(system_messages, 1);
+        assert_eq!(system_messages, 2);
     }
 
     #[test]
diff --git a/src/gateway/session_factory.rs b/src/gateway/session_factory.rs
index 8484c4f..741e98d 100644
--- a/src/gateway/session_factory.rs
+++ b/src/gateway/session_factory.rs
@@ -20,6 +20,7 @@ pub(crate) struct SessionFactory {
     prompt_injector: PromptInjector,
     conversations: Arc<dyn ConversationRepository>,
     skill_events: Arc<dyn SkillEventRepository>,
+    chat_history_ttl_hours: Option<u64>,
 }
 
 impl SessionFactory {
@@ -30,6 +31,7 @@ impl SessionFactory {
         prompt_injector: PromptInjector,
         conversations: Arc<dyn ConversationRepository>,
         skill_events: Arc<dyn SkillEventRepository>,
+        chat_history_ttl_hours: Option<u64>,
     ) -> Self {
         Self {
             provider_config,
@@ -38,6 +40,7 @@ impl SessionFactory {
             prompt_injector,
             conversations,
             skill_events,
+            chat_history_ttl_hours,
         }
     }
 
@@ -55,6 +58,7 @@ impl SessionFactory {
             self.prompt_injector.clone(),
             self.conversations.clone(),
             self.skill_events.clone(),
+            self.chat_history_ttl_hours,
         )
         .await
     }
diff --git a/src/gateway/session_history.rs b/src/gateway/session_history.rs
index a19923f..90247c8 100644
--- a/src/gateway/session_history.rs
+++ b/src/gateway/session_history.rs
@@ -19,6 +19,13 @@ fn preview_text(content: &str, max_chars: usize) -> String {
     preview.replace('\n', "\\n")
 }
 
+fn current_timestamp() -> i64 {
+    std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs() as i64
+}
+
 pub(crate) struct SessionHistory {
     channel_name: String,
     chat_histories: HashMap<String, Vec<ChatMessage>>,
@@ -27,6 +34,7 @@ pub(crate) struct SessionHistory {
     conversations: Arc<dyn ConversationRepository>,
     skill_events: Arc<dyn SkillEventRepository>,
     provider_config: LLMProviderConfig,
+    chat_history_ttl_hours: Option<u64>,
 }
 
 impl SessionHistory {
@@ -36,6 +44,7 @@ impl SessionHistory {
         conversations: Arc<dyn ConversationRepository>,
         skill_events: Arc<dyn SkillEventRepository>,
         provider_config: LLMProviderConfig,
+        chat_history_ttl_hours: Option<u64>,
     ) -> Self {
         Self {
             channel_name: channel_name.into(),
@@ -45,6 +54,7 @@ impl SessionHistory {
             conversations,
             skill_events,
             provider_config,
+            chat_history_ttl_hours,
         }
     }
 
@@ -62,6 +72,29 @@ impl SessionHistory {
     }
 
     pub(crate) fn ensure_chat_loaded(&mut self, chat_id: &str) -> Result<(), AgentError> {
+        // 获取 session 记录（用于检查最后活跃时间）
+        let session_record = self.ensure_persistent_session(chat_id)?;
+
+        // 检查是否超时
+        if let Some(ttl_hours) = self.chat_history_ttl_hours {
+            if ttl_hours > 0 {
+                let now = current_timestamp();
+                let elapsed_hours = (now - session_record.last_active_at) / 3600;
+                if elapsed_hours >= ttl_hours as i64 {
+                    tracing::info!(
+                        channel = %self.channel_name,
+                        chat_id = %chat_id,
+                        elapsed_hours = elapsed_hours,
+                        ttl_hours = ttl_hours,
+                        "Chat history expired, resetting context"
+                    );
+                    // 重置会话上下文（清空内存历史，但保留数据库记录）
+                    self.reset_chat_context(chat_id)?;
+                }
+            }
+        }
+
+        // 原有逻辑
         if self.chat_histories.contains_key(chat_id) {
             return self.ensure_initial_agent_prompt(chat_id);
         }
diff --git a/src/gateway/session_lifecycle.rs b/src/gateway/session_lifecycle.rs
index e81af98..e433269 100644
--- a/src/gateway/session_lifecycle.rs
+++ b/src/gateway/session_lifecycle.rs
@@ -14,9 +14,9 @@ pub(crate) struct SessionLifecycleService {
 }
 
 impl SessionLifecycleService {
-    pub(crate) fn new(session_ttl_hours: u64, session_factory: SessionFactory) -> Self {
+    pub(crate) fn new(session_factory: SessionFactory) -> Self {
         Self {
-            session_pool: SessionPool::new(session_ttl_hours, session_factory),
+            session_pool: SessionPool::new(session_factory),
         }
     }
 
diff --git a/src/gateway/session_pool.rs b/src/gateway/session_pool.rs
index 887ea95..9aa156c 100644
--- a/src/gateway/session_pool.rs
+++ b/src/gateway/session_pool.rs
@@ -1,6 +1,6 @@
 use std::collections::HashMap;
 use std::sync::Arc;
-use std::time::{Duration, Instant};
+use std::time::Instant;
 
 use tokio::sync::{Mutex, mpsc};
 
@@ -19,16 +19,14 @@ pub(crate) struct SessionPool {
 struct SessionPoolInner {
     sessions: HashMap<String, Arc<Mutex<Session>>>,
     session_timestamps: HashMap<String, Instant>,
-    session_ttl: Duration,
 }
 
 impl SessionPool {
-    pub(crate) fn new(session_ttl_hours: u64, session_factory: SessionFactory) -> Self {
+    pub(crate) fn new(session_factory: SessionFactory) -> Self {
         Self {
             inner: Arc::new(Mutex::new(SessionPoolInner {
                 sessions: HashMap::new(),
                 session_timestamps: HashMap::new(),
-                session_ttl: Duration::from_secs(session_ttl_hours * 3600),
             })),
             session_factory,
         }
@@ -37,38 +35,25 @@ impl SessionPool {
     pub(crate) async fn ensure_session(&self, channel_name: &str) -> Result<(), AgentError> {
         let mut inner = self.inner.lock().await;
 
-        let should_recreate = if let Some(last_active) = inner.session_timestamps.get(channel_name)
-        {
-            let elapsed = last_active.elapsed();
-            if elapsed > inner.session_ttl {
-                tracing::info!(channel = %channel_name, elapsed_hours = elapsed.as_secs() / 3600, "Session expired, recreating");
-                true
-            } else {
-                false
-            }
-        } else {
-            #[cfg(debug_assertions)]
-            tracing::debug!(channel = %channel_name, "Creating new session");
-            true
-        };
-
-        if should_recreate {
-            inner.sessions.remove(channel_name);
-
-            let (user_tx, _rx) = mpsc::channel::<WsOutbound>(100);
-            let session = self
-                .session_factory
-                .create(channel_name.to_string(), user_tx)
-                .await?;
-
-            inner
-                .sessions
-                .insert(channel_name.to_string(), Arc::new(Mutex::new(session)));
-            inner
-                .session_timestamps
-                .insert(channel_name.to_string(), Instant::now());
+        // 简化：只检查 session 是否存在，不做超时判断
+        if inner.sessions.contains_key(channel_name) {
+            return Ok(());
         }
 
+        // Session 不存在则创建
+        let (user_tx, _rx) = mpsc::channel::<WsOutbound>(100);
+        let session = self
+            .session_factory
+            .create(channel_name.to_string(), user_tx)
+            .await?;
+
+        inner
+            .sessions
+            .insert(channel_name.to_string(), Arc::new(Mutex::new(session)));
+        inner
+            .session_timestamps
+            .insert(channel_name.to_string(), Instant::now());
+
         Ok(())
     }
 
@@ -85,25 +70,7 @@ impl SessionPool {
     }
 
     pub(crate) async fn cleanup_expired_sessions(&self) -> usize {
-        let mut inner = self.inner.lock().await;
-        let now = Instant::now();
-        let expired_channels: Vec<String> = inner
-            .session_timestamps
-            .iter()
-            .filter_map(|(channel_name, last_active)| {
-                if now.duration_since(*last_active) > inner.session_ttl {
-                    Some(channel_name.clone())
-                } else {
-                    None
-                }
-            })
-            .collect();
-
-        for channel_name in &expired_channels {
-            inner.sessions.remove(channel_name);
-            inner.session_timestamps.remove(channel_name);
-        }
-
-        expired_channels.len()
+        // Session 级别不再自动清理，返回 0
+        0
     }
 }