diff --git a/src/gateway/agent_prompt_provider.rs b/src/gateway/agent_prompt_provider.rs
index 6f8e857..080c21d 100644
--- a/src/gateway/agent_prompt_provider.rs
+++ b/src/gateway/agent_prompt_provider.rs
@@ -34,37 +34,10 @@ impl AgentPromptProvider {
 
     /// 判断是否应该注入提示词
     ///
-    /// 规则：
-    /// - 首次对话（user_message_count == 0）始终注入
-    /// - 如果设置了 reinject_every > 0，且满足间隔条件，则重新注入
-    fn should_inject(&self, context: &SystemPromptContext) -> bool {
-        // 首次对话始终注入
-        if context.user_message_count == 0 {
-            return true;
-        }
-
-        // 检查是否需要重新注入
-        if self.reinject_every == 0 {
-            return false;
-        }
-
-        // 获取会话注入计数
-        let session_id = match &context.session_id {
-            Some(id) => id,
-            None => return false,
-        };
-
-        let reinjection_count = self
-            .repository
-            .get_session(session_id)
-            .ok()
-            .flatten()
-            .map(|session| session.agent_prompt_reinjection_count as usize)
-            .unwrap_or(0);
-
-        let expected_reinjections = context.user_message_count / self.reinject_every;
-
-        expected_reinjections > reinjection_count
+    /// 规则：每次处理用户消息都动态注入系统提示词
+    fn should_inject(&self, _context: &SystemPromptContext) -> bool {
+        // 每次消息都注入系统提示词
+        true
     }
 
     /// 记录注入事件
diff --git a/src/gateway/execution.rs b/src/gateway/execution.rs
index f525480..d1624ae 100644
--- a/src/gateway/execution.rs
+++ b/src/gateway/execution.rs
@@ -163,11 +163,16 @@ impl AgentExecutionService {
             }
             let enriched_content =
                 enrich_user_content_with_media_refs(request.content, &media_refs)?;
+
+            // 先计算 user_message_count（在添加新消息之前）
+            let history_before = session_guard.get_or_create_history(request.chat_id).clone();
+            let user_message_count = history_before.iter().filter(|m| m.role == "user").count();
+
             let user_message = session_guard.create_user_message(&enriched_content, media_refs);
             session_guard.append_persisted_message(request.chat_id, user_message.clone())?;
 
+            // 再获取包含新消息的完整历史记录
             let history = session_guard.get_or_create_history(request.chat_id).clone();
-            let user_message_count = history.iter().filter(|m| m.role == "user").count();
             session_guard.record_skill_offer(request.chat_id)?;
 
             let mut agent = session_guard.create_agent(
@@ -233,11 +238,15 @@ impl AgentExecutionService {
                 ),
             )?;
 
+            // 先计算 user_message_count（在添加新消息之前）
+            let history_before = session_guard.get_or_create_history(request.chat_id).clone();
+            let user_message_count = history_before.iter().filter(|m| m.role == "user").count();
+
             let user_message = session_guard.create_user_message(request.prompt, Vec::new());
             session_guard.append_persisted_message(request.chat_id, user_message.clone())?;
 
+            // 再获取包含新消息的完整历史记录
             let history = session_guard.get_or_create_history(request.chat_id).clone();
-            let user_message_count = history.iter().filter(|m| m.role == "user").count();
             session_guard.record_skill_offer(request.chat_id)?;
 
             let agent = session_guard.create_agent_with_provider_config(