diff --git a/Cargo.lock b/Cargo.lock
index 759fa9d..8888f95 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -28,6 +28,17 @@ version = "1.0.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 
+[[package]]
+name = "async-trait"
+version = "0.1.89"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9035ad2d096bed7955a320ee7e2230574d28fd3c3a0f186cbea1ff3c7eed5dbb"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "atomic-waker"
 version = "1.1.2"
@@ -1898,6 +1909,7 @@ version = "0.1.0"
 dependencies = [
  "aes",
  "anyhow",
+ "async-trait",
  "base64",
  "block-padding",
  "chrono",
diff --git a/Cargo.toml b/Cargo.toml
index 0caf7a8..a553c4f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -17,6 +17,7 @@ cipher = { version = "0.4", features = ["alloc"] }
 qrcode = "0.14"
 mime_guess = "2"
 tempfile = "3"
+async-trait = "0.1"
 snafu = "0.9"
 rand = "0.9"
 hex = "0.4"
diff --git a/examples/echo_bot.rs b/examples/echo_bot.rs
index cef680b..8024c3b 100644
--- a/examples/echo_bot.rs
+++ b/examples/echo_bot.rs
@@ -1,19 +1,16 @@
-use std::{future::Future, pin::Pin, sync::Arc};
+use std::sync::Arc;
 
+use async_trait::async_trait;
 use wechat_agent_rs::{Agent, ChatRequest, ChatResponse, LoginOptions, StartOptions, login, start};
 
 struct EchoAgent;
 
+#[async_trait]
 impl Agent for EchoAgent {
-    fn chat(
-        &self,
-        request: ChatRequest,
-    ) -> Pin<Box<dyn Future<Output = wechat_agent_rs::Result<ChatResponse>> + Send + '_>> {
-        Box::pin(async move {
-            Ok(ChatResponse {
-                text:  Some(format!("You said: {}", request.text)),
-                media: None,
-            })
+    async fn chat(&self, request: ChatRequest) -> wechat_agent_rs::Result<ChatResponse> {
+        Ok(ChatResponse {
+            text:  Some(format!("You said: {}", request.text)),
+            media: None,
         })
     }
 }
diff --git a/examples/openai_bot.rs b/examples/openai_bot.rs
index 0fc63d9..849e6ee 100644
--- a/examples/openai_bot.rs
+++ b/examples/openai_bot.rs
@@ -3,6 +3,7 @@ use std::{
     sync::{Arc, Mutex},
 };
 
+use async_trait::async_trait;
 use base64::Engine;
 use reqwest::Client;
 use serde_json::{Value, json};
@@ -37,88 +38,82 @@ impl OpenAIAgent {
     }
 }
 
+#[async_trait]
 impl Agent for OpenAIAgent {
-    fn chat(
-        &self,
-        request: ChatRequest,
-    ) -> std::pin::Pin<
-        Box<dyn std::future::Future<Output = wechat_agent_rs::Result<ChatResponse>> + Send + '_>,
-    > {
-        Box::pin(async move {
-            let user_content = if let Some(ref media) = request.media {
-                match media.media_type {
-                    wechat_agent_rs::MediaType::Image => {
-                        let data = std::fs::read(&media.file_path).context(IoSnafu)?;
-                        let b64 = base64::engine::general_purpose::STANDARD.encode(&data);
-                        json!([
-                            {"type": "text", "text": request.text},
-                            {"type": "image_url", "image_url": {"url": format!("data:{};base64,{b64}", media.mime_type)}}
-                        ])
-                    }
-                    _ => {
-                        json!(format!(
-                            "{}\n[Attachment: {} ({})]",
-                            request.text,
-                            media.file_name.as_deref().unwrap_or("file"),
-                            media.mime_type
-                        ))
-                    }
+    async fn chat(&self, request: ChatRequest) -> wechat_agent_rs::Result<ChatResponse> {
+        let user_content = if let Some(ref media) = request.media {
+            match media.media_type {
+                wechat_agent_rs::MediaType::Image => {
+                    let data = std::fs::read(&media.file_path).context(IoSnafu)?;
+                    let b64 = base64::engine::general_purpose::STANDARD.encode(&data);
+                    json!([
+                        {"type": "text", "text": request.text},
+                        {"type": "image_url", "image_url": {"url": format!("data:{};base64,{b64}", media.mime_type)}}
+                    ])
                 }
-            } else {
-                json!(request.text)
-            };
-
-            // Build messages while holding the lock, then drop it before await
-            let messages = {
-                let mut histories = self.histories.lock().unwrap();
-                let history = histories
-                    .entry(request.conversation_id.clone())
-                    .or_default();
-
-                history.push(json!({"role": "user", "content": user_content}));
-
-                if history.len() > 50 {
-                    history.drain(0..history.len() - 50);
+                _ => {
+                    json!(format!(
+                        "{}\n[Attachment: {} ({})]",
+                        request.text,
+                        media.file_name.as_deref().unwrap_or("file"),
+                        media.mime_type
+                    ))
                 }
-
-                let mut messages = vec![json!({"role": "system", "content": self.system_prompt})];
-                messages.extend(history.iter().cloned());
-                drop(histories);
-                messages
-            };
-
-            let resp = self
-                .client
-                .post(format!("{}/chat/completions", self.base_url))
-                .header("Authorization", format!("Bearer {}", self.api_key))
-                .json(&json!({
-                    "model": self.model,
-                    "messages": messages,
-                }))
-                .send()
-                .await
-                .context(HttpSnafu)?
-                .json::<Value>()
-                .await
-                .context(HttpSnafu)?;
-
-            let reply = resp["choices"][0]["message"]["content"]
-                .as_str()
-                .unwrap_or("(no response)")
-                .to_string();
-
-            // Re-acquire lock to store assistant reply
-            self.histories
-                .lock()
-                .unwrap()
-                .entry(request.conversation_id)
-                .or_default()
-                .push(json!({"role": "assistant", "content": &reply}));
-
-            Ok(ChatResponse {
-                text:  Some(reply),
-                media: None,
-            })
+            }
+        } else {
+            json!(request.text)
+        };
+
+        // Build messages while holding the lock, then drop it before await
+        let messages = {
+            let mut histories = self.histories.lock().unwrap();
+            let history = histories
+                .entry(request.conversation_id.clone())
+                .or_default();
+
+            history.push(json!({"role": "user", "content": user_content}));
+
+            if history.len() > 50 {
+                history.drain(0..history.len() - 50);
+            }
+
+            let mut messages = vec![json!({"role": "system", "content": self.system_prompt})];
+            messages.extend(history.iter().cloned());
+            drop(histories);
+            messages
+        };
+
+        let resp = self
+            .client
+            .post(format!("{}/chat/completions", self.base_url))
+            .header("Authorization", format!("Bearer {}", self.api_key))
+            .json(&json!({
+                "model": self.model,
+                "messages": messages,
+            }))
+            .send()
+            .await
+            .context(HttpSnafu)?
+            .json::<Value>()
+            .await
+            .context(HttpSnafu)?;
+
+        let reply = resp["choices"][0]["message"]["content"]
+            .as_str()
+            .unwrap_or("(no response)")
+            .to_string();
+
+        // Re-acquire lock to store assistant reply
+        self.histories
+            .lock()
+            .unwrap()
+            .entry(request.conversation_id)
+            .or_default()
+            .push(json!({"role": "assistant", "content": &reply}));
+
+        Ok(ChatResponse {
+            text:  Some(reply),
+            media: None,
         })
     }
 }
diff --git a/src/models.rs b/src/models.rs
index 11765cb..09ef8ef 100644
--- a/src/models.rs
+++ b/src/models.rs
@@ -1,17 +1,14 @@
-use std::{future::Future, pin::Pin};
-
+use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 
 /// Trait that application code implements to handle incoming chat messages.
 ///
 /// The SDK calls [`Agent::chat`] for every incoming message and sends the
 /// returned [`ChatResponse`] back to the `WeChat` user.
+#[async_trait]
 pub trait Agent: Send + Sync {
     /// Processes an incoming chat request and returns a response.
-    fn chat(
-        &self,
-        request: ChatRequest,
-    ) -> Pin<Box<dyn Future<Output = crate::Result<ChatResponse>> + Send + '_>>;
+    async fn chat(&self, request: ChatRequest) -> crate::Result<ChatResponse>;
 }
 
 /// An incoming chat message delivered to the agent.