diff --git a/src/agent/agent_loop.rs b/src/agent/agent_loop.rs
index 9071db0..ea9bec2 100644
--- a/src/agent/agent_loop.rs
+++ b/src/agent/agent_loop.rs
@@ -383,7 +383,7 @@ impl AgentLoop {
         // Build and inject system prompt if not present
         let has_system = messages.first().is_some_and(|m| m.role == "system");
         if !has_system {
-            let system_prompt = build_system_prompt(&self.workspace_dir, &self.model_name, &self.tools, None, None);
+            let system_prompt = build_system_prompt(&self.workspace_dir, &self.model_name, &self.tools, None, None, false);
             #[cfg(debug_assertions)]
             tracing::debug!("System prompt injected:\n{}", system_prompt);
             messages.insert(0, ChatMessage::system(system_prompt));
diff --git a/src/agent/system_prompt.rs b/src/agent/system_prompt.rs
index bcc6d30..a23611e 100644
--- a/src/agent/system_prompt.rs
+++ b/src/agent/system_prompt.rs
@@ -21,6 +21,8 @@ pub struct PromptContext<'a> {
     pub session_id: Option<&'a str>,
     /// Pre-fetched memory context string to inject.
     pub memory_context: Option<&'a str>,
+    /// Whether this session has compressed history available via timeline_recall.
+    pub has_compressed_history: bool,
 }
 
 /// Trait for system prompt sections.
@@ -46,6 +48,7 @@ impl SystemPromptBuilder {
                 Box::new(WorkspaceSection),
                 Box::new(UserProfileSection),
                 Box::new(MemorySection),
+                Box::new(HistorySection),
                 Box::new(DateTimeSection),
                 Box::new(RuntimeSection),
                 Box::new(CrossChannelSection),
@@ -303,6 +306,23 @@ impl PromptSection for MemorySection {
     }
 }
 
+/// Prompt agent to use timeline_recall if compressed history exists.
+pub struct HistorySection;
+
+impl PromptSection for HistorySection {
+    fn name(&self) -> &str {
+        "history"
+    }
+
+    fn build(&self, ctx: &PromptContext<'_>) -> String {
+        if ctx.has_compressed_history {
+            "## 历史会话\n之前的对话摘要已归档。如需回顾历史上下文，使用 `timeline_recall` 工具搜索。".to_string()
+        } else {
+            String::new()
+        }
+    }
+}
+
 // === Helper Functions ===
 
 /// Get user config directory (~/.picobot/).
@@ -346,6 +366,7 @@ pub fn build_system_prompt(
     tools: &ToolRegistry,
     session_id: Option<&str>,
     memory_context: Option<&str>,
+    has_compressed_history: bool,
 ) -> String {
     let ctx = PromptContext {
         workspace_dir,
@@ -353,6 +374,7 @@ pub fn build_system_prompt(
         tools,
         session_id,
         memory_context,
+        has_compressed_history,
     };
     SystemPromptBuilder::with_defaults().build(&ctx)
 }
@@ -373,6 +395,7 @@ mod tests {
             tools: &tools,
             session_id: None,
             memory_context: None,
+            has_compressed_history: false,
         };
 
         let prompt = SystemPromptBuilder::with_defaults().build(&ctx);
@@ -402,7 +425,7 @@ mod tests {
         let temp_dir = std::env::temp_dir();
         let tools = ToolRegistry::new();
 
-        let prompt = build_system_prompt(&temp_dir, "test-model", &tools, None, None);
+        let prompt = build_system_prompt(&temp_dir, "test-model", &tools, None, None, false);
 
         assert!(!prompt.is_empty());
         assert!(prompt.contains("test-model"));
@@ -419,6 +442,7 @@ mod tests {
             tools: &tools,
             session_id: None,
             memory_context: Some("- user_pref: Prefers Rust"),
+            has_compressed_history: false,
         };
 
         let prompt = SystemPromptBuilder::with_defaults().build(&ctx);
@@ -437,6 +461,7 @@ mod tests {
             tools: &tools,
             session_id: None,
             memory_context: None,
+            has_compressed_history: false,
         };
 
         let prompt = SystemPromptBuilder::with_defaults().build(&ctx);
diff --git a/src/tools/chat_manager.rs b/src/tools/chat_manager.rs
index 2c18604..51cdcfb 100644
--- a/src/tools/chat_manager.rs
+++ b/src/tools/chat_manager.rs
@@ -264,6 +264,7 @@ mod tests {
                 routing_info: None,
                 deleted_at: None,
             last_consolidated_at: None,
+            last_compressed_message_at: None,
             };
             storage.upsert_session(&meta).await.unwrap();
         }
@@ -298,6 +299,7 @@ mod tests {
             routing_info: None,
             deleted_at: None,
             last_consolidated_at: None,
+            last_compressed_message_at: None,
         };
         storage.upsert_session(&meta).await.unwrap();