diff --git a/.vscode/launch.json b/.vscode/launch.json
deleted file mode 100644
index 959b4ce..0000000
--- a/.vscode/launch.json
+++ /dev/null
@@ -1,49 +0,0 @@
-{
-    // Use IntelliSense to learn about possible attributes.
-    // Hover to view descriptions of existing attributes.
-    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
-    "version": "0.2.0",
-    "configurations": [
-        {
-            "type": "lldb",
-            "request": "launch",
-            "name": "Debug executable 'puppet'",
-            "cargo": {
-                "args": [
-                    "build",
-                    "--bin=puppet",
-                    "--package=puppet"
-                ],
-                "filter": {
-                    "name": "puppet",
-                    "kind": "bin"
-                }
-            },
-            "args": [
-                "chat",
-                "--conf",
-                "./env/conf.json"
-            ],
-            "cwd": "${workspaceFolder}"
-        },
-        {
-            "type": "lldb",
-            "request": "launch",
-            "name": "Debug unit tests in executable 'puppet'",
-            "cargo": {
-                "args": [
-                    "test",
-                    "--no-run",
-                    "--bin=puppet",
-                    "--package=puppet"
-                ],
-                "filter": {
-                    "name": "puppet",
-                    "kind": "bin"
-                }
-            },
-            "args": [],
-            "cwd": "${workspaceFolder}"
-        }
-    ]
-}
\ No newline at end of file
diff --git a/.vscode/settings.json b/.vscode/settings.json
deleted file mode 100644
index ad7705f..0000000
--- a/.vscode/settings.json
+++ /dev/null
@@ -1,27 +0,0 @@
-{
-    "workbench.colorCustomizations": {
-        "activityBar.activeBackground": "#c8adc3",
-        "activityBar.background": "#c8adc3",
-        "activityBar.foreground": "#15202b",
-        "activityBar.inactiveForeground": "#15202b99",
-        "activityBarBadge.background": "#6b724d",
-        "activityBarBadge.foreground": "#e7e7e7",
-        "commandCenter.border": "#15202b99",
-        "sash.hoverBorder": "#c8adc3",
-        "statusBar.background": "#b48ead",
-        "statusBar.foreground": "#15202b",
-        "statusBarItem.hoverBackground": "#a06f97",
-        "statusBarItem.remoteBackground": "#b48ead",
-        "statusBarItem.remoteForeground": "#15202b",
-        "titleBar.activeBackground": "#b48ead",
-        "titleBar.activeForeground": "#15202b",
-        "titleBar.inactiveBackground": "#b48ead99",
-        "titleBar.inactiveForeground": "#15202b99"
-    },
-    "peacock.color": "#B48EAD",
-    "cSpell.words": [
-        "gcloud",
-        "openai"
-    ],
-    "rust-analyzer.showUnlinkedFileNotification": false
-}
\ No newline at end of file
diff --git a/src/azure/chatgpt.rs b/src/azure/chatgpt.rs
index d414cd9..41779b3 100644
--- a/src/azure/chatgpt.rs
+++ b/src/azure/chatgpt.rs
@@ -29,21 +29,24 @@ use crate::util::exception::Exception;
 use crate::util::http_client;
 use crate::util::json;
 
-pub struct ChatGPT {
+pub struct ChatGPT<L>
+where
+    L: ChatListener,
+{
     url: String,
     api_key: String,
     messages: Rc<Vec<ChatRequestMessage>>,
     tools: Option<Rc<[Tool]>>,
     function_store: FunctionStore,
+    listener: Option<L>,
     pub option: Option<ChatOption>,
-    pub listener: Option<Box<dyn ChatListener>>,
     last_assistant_message: String,
 }
 
 type FunctionCall = HashMap<i64, (String, String, String)>;
 
-impl ChatGPT {
-    pub fn new(endpoint: String, model: String, api_key: String, function_store: FunctionStore) -> Self {
+impl<L: ChatListener> ChatGPT<L> {
+    pub fn new(endpoint: String, model: String, api_key: String, function_store: FunctionStore, listener: Option<L>) -> Self {
         let url = format!("{endpoint}/openai/deployments/{model}/chat/completions?api-version=2024-06-01");
         let tools: Option<Rc<[Tool]>> = function_store.declarations.is_empty().not().then_some(
             function_store
@@ -61,8 +64,8 @@ impl ChatGPT {
             messages: Rc::new(vec![]),
             tools,
             function_store,
+            listener,
             last_assistant_message: String::new(),
-            listener: None,
             option: None,
         }
     }
@@ -141,7 +144,7 @@ impl ChatGPT {
                     assistant_message.push_str(&value);
 
                     if let Some(listener) = self.listener.as_ref() {
-                        listener.on_event(ChatEvent::Delta(value));
+                        listener.on_event(ChatEvent::Delta(value)).await?;
                     }
                 }
             }
@@ -163,7 +166,7 @@ impl ChatGPT {
             Ok(Some(function_calls))
         } else {
             if let Some(listener) = self.listener.as_ref() {
-                listener.on_event(ChatEvent::End(usage));
+                listener.on_event(ChatEvent::End(usage)).await?;
             }
             Ok(None)
         }
diff --git a/src/command/chat.rs b/src/command/chat.rs
index 81f7508..f988fef 100644
--- a/src/command/chat.rs
+++ b/src/command/chat.rs
@@ -1,4 +1,3 @@
-use std::io::Write;
 use std::mem;
 use std::path::PathBuf;
 
@@ -6,11 +5,10 @@ use clap::Args;
 use tokio::io::stdin;
 use tokio::io::AsyncBufReadExt;
 use tokio::io::BufReader;
-use tracing::info;
 
 use crate::llm;
-use crate::llm::ChatEvent;
-use crate::llm::ChatListener;
+use crate::llm::ConsolePrinter;
+use crate::util::console;
 use crate::util::exception::Exception;
 
 #[derive(Args)]
@@ -22,38 +20,19 @@ pub struct Chat {
     name: String,
 }
 
-struct ConsoleHandler;
-
-impl ChatListener for ConsoleHandler {
-    fn on_event(&self, event: ChatEvent) {
-        match event {
-            ChatEvent::Delta(data) => {
-                print_flush(&data).unwrap();
-            }
-            ChatEvent::End(usage) => {
-                println!();
-                info!(
-                    "usage, request_tokens={}, response_tokens={}",
-                    usage.request_tokens, usage.response_tokens
-                );
-            }
-        }
-    }
-}
-
 impl Chat {
     pub async fn execute(&self) -> Result<(), Exception> {
         let config = llm::load(&self.conf).await?;
-        let mut model = config.create(&self.name)?;
-        model.listener(Box::new(ConsoleHandler));
+        let mut model = config.create(&self.name, Some(ConsolePrinter))?;
 
         let reader = BufReader::new(stdin());
         let mut lines = reader.lines();
-
         let mut files: Vec<PathBuf> = vec![];
         loop {
-            print_flush("> ")?;
-            let Some(line) = lines.next_line().await? else { break };
+            console::print("> ").await?;
+            let Some(line) = lines.next_line().await? else {
+                break;
+            };
             if line.starts_with("/quit") {
                 break;
             }
@@ -71,9 +50,3 @@ impl Chat {
         Ok(())
     }
 }
-
-fn print_flush(message: &str) -> Result<(), Exception> {
-    print!("{message}");
-    std::io::stdout().flush()?;
-    Ok(())
-}
diff --git a/src/command/complete.rs b/src/command/complete.rs
index 668d015..bea5f56 100644
--- a/src/command/complete.rs
+++ b/src/command/complete.rs
@@ -1,4 +1,3 @@
-use std::io::Write;
 use std::mem;
 use std::path::PathBuf;
 use std::str::FromStr;
@@ -12,9 +11,9 @@ use tokio::io::BufReader;
 use tracing::info;
 
 use crate::llm;
-use crate::llm::ChatEvent;
 use crate::llm::ChatListener;
 use crate::llm::ChatOption;
+use crate::llm::ConsolePrinter;
 use crate::util::exception::Exception;
 
 #[derive(Args)]
@@ -29,26 +28,6 @@ pub struct Complete {
     name: String,
 }
 
-struct Listener;
-
-impl ChatListener for Listener {
-    fn on_event(&self, event: ChatEvent) {
-        match event {
-            ChatEvent::Delta(data) => {
-                print!("{data}");
-                let _ = std::io::stdout().flush();
-            }
-            ChatEvent::End(usage) => {
-                println!();
-                info!(
-                    "usage, request_tokens={}, response_tokens={}",
-                    usage.request_tokens, usage.response_tokens
-                );
-            }
-        }
-    }
-}
-
 enum ParserState {
     System,
     User,
@@ -58,8 +37,7 @@ enum ParserState {
 impl Complete {
     pub async fn execute(&self) -> Result<(), Exception> {
         let config = llm::load(&self.conf).await?;
-        let mut model = config.create(&self.name)?;
-        model.listener(Box::new(Listener));
+        let mut model = config.create(&self.name, Some(ConsolePrinter))?;
 
         let prompt = fs::OpenOptions::new().read(true).open(&self.prompt).await?;
         let reader = BufReader::new(prompt);
@@ -68,9 +46,7 @@ impl Complete {
         let mut files: Vec<PathBuf> = vec![];
         let mut message = String::new();
         let mut state = ParserState::User;
-        loop {
-            let Some(line) = lines.next_line().await? else { break };
-
+        while let Some(line) = lines.next_line().await? {
             if line.is_empty() {
                 continue;
             }
@@ -122,7 +98,10 @@ impl Complete {
     }
 }
 
-async fn add_message(model: &mut llm::Model, state: &ParserState, message: String, files: Vec<PathBuf>) -> Result<(), Exception> {
+async fn add_message<L>(model: &mut llm::Model<L>, state: &ParserState, message: String, files: Vec<PathBuf>) -> Result<(), Exception>
+where
+    L: ChatListener,
+{
     match state {
         ParserState::System => {
             info!("system message: {}", message);
diff --git a/src/gcloud/gemini.rs b/src/gcloud/gemini.rs
index 4656343..a00b973 100644
--- a/src/gcloud/gemini.rs
+++ b/src/gcloud/gemini.rs
@@ -32,20 +32,23 @@ use crate::util::exception::Exception;
 use crate::util::http_client;
 use crate::util::json;
 
-pub struct Gemini {
+pub struct Gemini<L>
+where
+    L: ChatListener,
+{
     url: String,
     messages: Rc<Vec<Content>>,
     system_instruction: Option<Rc<Content>>,
     tools: Option<Rc<[Tool]>>,
     function_store: FunctionStore,
+    listener: Option<L>,
     pub option: Option<ChatOption>,
-    pub listener: Option<Box<dyn ChatListener>>,
     last_model_message: String,
     usage: Usage,
 }
 
-impl Gemini {
-    pub fn new(endpoint: String, project: String, location: String, model: String, function_store: FunctionStore) -> Self {
+impl<L: ChatListener> Gemini<L> {
+    pub fn new(endpoint: String, project: String, location: String, model: String, function_store: FunctionStore, listener: Option<L>) -> Self {
         let url = format!("{endpoint}/v1/projects/{project}/locations/{location}/publishers/google/models/{model}:streamGenerateContent");
         Gemini {
             url,
@@ -55,8 +58,8 @@ impl Gemini {
                 function_declarations: function_store.declarations.to_vec(),
             }])),
             function_store,
+            listener,
             option: None,
-            listener: None,
             last_model_message: String::with_capacity(1024),
             usage: Usage::default(),
         }
@@ -129,7 +132,7 @@ impl Gemini {
                 } else if let Some(text) = part.text {
                     model_message.push_str(&text);
                     if let Some(listener) = self.listener.as_ref() {
-                        listener.on_event(ChatEvent::Delta(text));
+                        listener.on_event(ChatEvent::Delta(text)).await?;
                     }
                 }
             }
@@ -147,7 +150,7 @@ impl Gemini {
 
         let usage = mem::take(&mut self.usage);
         if let Some(listener) = self.listener.as_ref() {
-            listener.on_event(ChatEvent::End(usage));
+            listener.on_event(ChatEvent::End(usage)).await?;
         }
 
         Ok(None)
diff --git a/src/llm.rs b/src/llm.rs
index 84a6040..d45f892 100644
--- a/src/llm.rs
+++ b/src/llm.rs
@@ -7,6 +7,7 @@ use tracing::info;
 use crate::azure::chatgpt::ChatGPT;
 use crate::gcloud::gemini::Gemini;
 use crate::llm::config::Config;
+use crate::util::console;
 use crate::util::exception::Exception;
 use crate::util::json;
 
@@ -14,7 +15,7 @@ pub mod config;
 pub mod function;
 
 pub trait ChatListener {
-    fn on_event(&self, event: ChatEvent);
+    async fn on_event(&self, event: ChatEvent) -> Result<(), Exception>;
 }
 
 pub enum ChatEvent {
@@ -33,12 +34,15 @@ pub struct Usage {
     pub response_tokens: i32,
 }
 
-pub enum Model {
-    ChatGPT(ChatGPT),
-    Gemini(Gemini),
+pub enum Model<L>
+where
+    L: ChatListener,
+{
+    ChatGPT(ChatGPT<L>),
+    Gemini(Gemini<L>),
 }
 
-impl Model {
+impl<L: ChatListener> Model<L> {
     pub async fn chat(&mut self) -> Result<String, Exception> {
         match self {
             Model::ChatGPT(model) => model.chat().await,
@@ -46,13 +50,6 @@ impl Model {
         }
     }
 
-    pub fn listener(&mut self, listener: Box<dyn ChatListener>) {
-        match self {
-            Model::ChatGPT(model) => model.listener = Some(listener),
-            Model::Gemini(model) => model.listener = Some(listener),
-        }
-    }
-
     pub fn system_message(&mut self, message: String) {
         match self {
             Model::ChatGPT(model) => model.system_message(message),
@@ -88,3 +85,24 @@ pub async fn load(path: &Path) -> Result<Config, Exception> {
     let config: Config = json::from_json(&content)?;
     Ok(config)
 }
+
+pub struct ConsolePrinter;
+
+impl ChatListener for ConsolePrinter {
+    async fn on_event(&self, event: ChatEvent) -> Result<(), Exception> {
+        match event {
+            ChatEvent::Delta(data) => {
+                console::print(&data).await?;
+                Ok(())
+            }
+            ChatEvent::End(usage) => {
+                console::print("\n").await?;
+                info!(
+                    "usage, request_tokens={}, response_tokens={}",
+                    usage.request_tokens, usage.response_tokens
+                );
+                Ok(())
+            }
+        }
+    }
+}
diff --git a/src/llm/config.rs b/src/llm/config.rs
index f91e2d7..b72611d 100644
--- a/src/llm/config.rs
+++ b/src/llm/config.rs
@@ -4,6 +4,7 @@ use rand::Rng;
 use serde::Deserialize;
 use serde_json::json;
 
+use super::ChatListener;
 use crate::azure::chatgpt::ChatGPT;
 use crate::gcloud::gemini::Gemini;
 use crate::llm::function::Function;
@@ -27,7 +28,10 @@ pub struct ModelConfig {
 }
 
 impl Config {
-    pub fn create(&self, name: &str) -> Result<Model, Exception> {
+    pub fn create<L>(&self, name: &str, listener: Option<L>) -> Result<Model<L>, Exception>
+    where
+        L: ChatListener,
+    {
         let config = self
             .models
             .get(name)
@@ -41,6 +45,7 @@ impl Config {
                 config.params.get("model").unwrap().to_string(),
                 config.params.get("api_key").unwrap().to_string(),
                 function_store,
+                listener,
             )),
             Provider::GCloud => Model::Gemini(Gemini::new(
                 config.endpoint.to_string(),
@@ -48,6 +53,7 @@ impl Config {
                 config.params.get("location").unwrap().to_string(),
                 config.params.get("model").unwrap().to_string(),
                 function_store,
+                listener,
             )),
         };
 
diff --git a/src/util.rs b/src/util.rs
index 3b0844d..f99495f 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -1,3 +1,4 @@
+pub mod console;
 pub mod exception;
 pub mod http_client;
 pub mod json;
diff --git a/src/util/console.rs b/src/util/console.rs
new file mode 100644
index 0000000..4efb461
--- /dev/null
+++ b/src/util/console.rs
@@ -0,0 +1,11 @@
+use tokio::io::stdout;
+use tokio::io::AsyncWriteExt;
+
+use super::exception::Exception;
+
+pub async fn print(text: &str) -> Result<(), Exception> {
+    let out = &mut stdout();
+    out.write_all(text.as_bytes()).await?;
+    out.flush().await?;
+    Ok(())
+}