feat: add /help command to display all supported commands

- Implemented HelpCommandHandler to handle the /help command.
- Added CommandMetadata struct to store command metadata.
- Registered new command handlers for GetCurrentSession, ListSessions, LoadSession, and SwitchSession.
- Updated existing command handlers to provide metadata for help command.
- Removed deprecated SessionQueryCommandHandler.
- Added new command handlers for listing sessions and loading sessions.

src/command/adapters/channel.rs

@@ -105,6 +105,11 @@ impl InputAdapter for ChannelInputAdapter {
             return Ok(Some(Command::GetCurrentSession));
         }
 
+        // 解析 /help 命令 - 显示所有支持的命令
+        if trimmed == "/help" {
+            return Ok(Some(Command::Help));
+        }
+
         // 不是命令，返回 None
         Ok(None)
     }

src/command/adapters/cli.rs

@@ -106,6 +106,11 @@ impl InputAdapter for CliInputAdapter {
             return Ok(Some(Command::GetCurrentSession));
         }
 
+        // 解析 /help 命令 - 显示所有支持的命令
+        if trimmed == "/help" {
+            return Ok(Some(Command::Help));
+        }
+
         // 不是命令，返回 None
         Ok(None)
     }

src/command/handler.rs

@@ -5,6 +5,15 @@ use crate::command::Command;
 use crate::agent::AgentError;
 use crate::gateway::session::SessionManager;
 use async_trait::async_trait;
+use std::sync::Arc;
+
+/// 命令元数据（用于帮助系统）
+#[derive(Debug, Clone)]
+pub struct CommandMetadata {
+    pub name: &'static str,
+    pub description: &'static str,
+    pub usage: &'static str,
+}
 
 /// 命令处理器 trait
 ///
@@ -15,6 +24,11 @@ pub trait CommandHandler: Send + Sync {
     /// 是否可以处理此命令
     fn can_handle(&self, cmd: &Command) -> bool;
 
+    /// 返回命令元数据（用于 /help 命令）
+    fn metadata(&self) -> Option<CommandMetadata> {
+        None
+    }
+
     /// 执行命令
     ///
     /// # Arguments
@@ -64,6 +78,7 @@ pub trait InChatCommandHandler: Send + Sync {
 /// 负责将命令分发到合适的处理器
 pub struct CommandRouter {
     handlers: Vec<Box<dyn CommandHandler>>,
+    metadata: Arc<std::sync::Mutex<Vec<CommandMetadata>>>,
 }
 
 impl CommandRouter {
@@ -71,6 +86,7 @@ impl CommandRouter {
     pub fn new() -> Self {
         Self {
             handlers: Vec::new(),
+            metadata: Arc::new(std::sync::Mutex::new(Vec::new())),
         }
     }
 
@@ -79,9 +95,17 @@ impl CommandRouter {
     /// # Arguments
     /// * `handler` - 要注册的处理器
     pub fn register(&mut self, handler: Box<dyn CommandHandler>) {
+        if let Some(meta) = handler.metadata() {
+            self.metadata.lock().unwrap().push(meta);
+        }
         self.handlers.push(handler);
     }
 
+    /// 获取已注册命令的元数据列表（用于 Help 命令）
+    pub fn metadata_arc(&self) -> Arc<std::sync::Mutex<Vec<CommandMetadata>>> {
+        self.metadata.clone()
+    }
+
     /// 分发命令到合适的处理器
     ///
     /// # Arguments

src/command/handlers/get_current.rs

@@ -0,0 +1,96 @@
+use crate::command::context::CommandContext;
+use crate::command::handler::{CommandHandler, CommandMetadata};
+use crate::command::response::{CommandError, CommandResponse, MessageKind};
+use crate::command::Command;
+use crate::storage::SessionStore;
+use async_trait::async_trait;
+use std::sync::Arc;
+
+/// 获取当前话题命令处理器
+pub struct GetCurrentSessionCommandHandler {
+    store: Arc<SessionStore>,
+}
+
+impl GetCurrentSessionCommandHandler {
+    pub fn new(store: Arc<SessionStore>) -> Self {
+        Self { store }
+    }
+}
+
+#[async_trait]
+impl CommandHandler for GetCurrentSessionCommandHandler {
+    fn can_handle(&self, cmd: &Command) -> bool {
+        matches!(cmd, Command::GetCurrentSession)
+    }
+
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "current",
+            description: "获取当前话题信息",
+            usage: "/current",
+        })
+    }
+
+    async fn handle(
+        &self,
+        cmd: Command,
+        ctx: CommandContext,
+    ) -> Result<CommandResponse, CommandError> {
+        match cmd {
+            Command::GetCurrentSession => handle_get_current_session(self, ctx).await,
+            _ => unreachable!(),
+        }
+    }
+}
+
+async fn handle_get_current_session(
+    handler: &GetCurrentSessionCommandHandler,
+    ctx: CommandContext,
+) -> Result<CommandResponse, CommandError> {
+    let topic_id = ctx.topic_id.as_deref()
+        .ok_or_else(|| CommandError::new("NO_CURRENT_TOPIC", "No current topic"))?;
+
+    let topic = handler
+        .store
+        .get_topic(topic_id)
+        .map_err(|e| CommandError::new("GET_TOPIC_ERROR", e.to_string()))?
+        .ok_or_else(|| CommandError::new("TOPIC_NOT_FOUND", format!("Topic not found: {}", topic_id)))?;
+
+    let last_active = format_time_ago(topic.last_active_at);
+    let created_at = format_time_ago(topic.created_at);
+
+    let message = format!(
+        "Current Topic:\n\n  Topic ID: {}\n  Title: {}\n  Messages: {}\n  Created: {}\n  Last Active: {}",
+        topic.id,
+        topic.title,
+        topic.message_count,
+        created_at,
+        last_active
+    );
+
+    Ok(CommandResponse::success(ctx.request_id)
+        .with_message(MessageKind::Notification, &message)
+        .with_metadata("topic_id", &topic.id)
+        .with_metadata("title", &topic.title)
+        .with_metadata("message_count", &topic.message_count.to_string()))
+}
+
+fn format_time_ago(timestamp_ms: i64) -> String {
+    let now = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap()
+        .as_millis() as i64;
+
+    let diff_ms = now - timestamp_ms;
+    let diff_secs = diff_ms / 1000;
+
+    if diff_secs < 60 {
+        "just now".to_string()
+    } else if diff_secs < 3600 {
+        format!("{} mins ago", diff_secs / 60)
+    } else if diff_secs < 86400 {
+        format!("{} hours ago", diff_secs / 3600)
+    } else {
+        format!("{} days ago", diff_secs / 86400)
+    }
+}

src/command/handlers/help.rs

@@ -0,0 +1,61 @@
+use crate::command::context::CommandContext;
+use crate::command::handler::{CommandHandler, CommandMetadata};
+use crate::command::response::{CommandError, CommandResponse, MessageKind};
+use crate::command::Command;
+use async_trait::async_trait;
+use std::sync::{Arc, Mutex};
+
+/// Help 命令处理器
+///
+/// 显示所有支持的命令列表
+pub struct HelpCommandHandler {
+    metadata: Arc<Mutex<Vec<CommandMetadata>>>,
+}
+
+impl HelpCommandHandler {
+    /// 创建新的 Help 命令处理器
+    ///
+    /// # Arguments
+    /// * `metadata` - CommandRouter 的元数据列表引用
+    pub fn new(metadata: Arc<Mutex<Vec<CommandMetadata>>>) -> Self {
+        Self { metadata }
+    }
+}
+
+#[async_trait]
+impl CommandHandler for HelpCommandHandler {
+    fn can_handle(&self, cmd: &Command) -> bool {
+        matches!(cmd, Command::Help)
+    }
+
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "help",
+            description: "显示所有支持的命令",
+            usage: "/help",
+        })
+    }
+
+    async fn handle(
+        &self,
+        _cmd: Command,
+        ctx: CommandContext,
+    ) -> Result<CommandResponse, CommandError> {
+        let metadata = self.metadata.lock().unwrap();
+        let help_text = format_help(&metadata);
+
+        Ok(CommandResponse::success(ctx.request_id)
+            .with_message(MessageKind::Text, &help_text))
+    }
+}
+
+/// 格式化帮助文本
+fn format_help(commands: &[CommandMetadata]) -> String {
+    let mut output = String::from("# 支持的命令\n\n");
+
+    for cmd in commands {
+        output.push_str(&format!("**{}** - {}\n", cmd.usage, cmd.description));
+    }
+
+    output
+}

src/command/handlers/list_sessions.rs

@@ -0,0 +1,136 @@
+use crate::command::context::CommandContext;
+use crate::command::handler::{CommandHandler, CommandMetadata};
+use crate::command::response::{CommandError, CommandResponse, MessageKind};
+use crate::command::Command;
+use crate::storage::SessionStore;
+use async_trait::async_trait;
+use std::sync::Arc;
+
+/// 列出话题命令处理器
+pub struct ListSessionsCommandHandler {
+    store: Arc<SessionStore>,
+}
+
+impl ListSessionsCommandHandler {
+    pub fn new(store: Arc<SessionStore>) -> Self {
+        Self { store }
+    }
+}
+
+#[async_trait]
+impl CommandHandler for ListSessionsCommandHandler {
+    fn can_handle(&self, cmd: &Command) -> bool {
+        matches!(cmd, Command::ListSessions { .. })
+    }
+
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "list",
+            description: "列出所有话题",
+            usage: "/list [all]",
+        })
+    }
+
+    async fn handle(
+        &self,
+        cmd: Command,
+        ctx: CommandContext,
+    ) -> Result<CommandResponse, CommandError> {
+        match cmd {
+            Command::ListSessions { include_archived } => {
+                handle_list_sessions(self, include_archived, ctx).await
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+
+async fn handle_list_sessions(
+    handler: &ListSessionsCommandHandler,
+    _include_archived: bool,
+    ctx: CommandContext,
+) -> Result<CommandResponse, CommandError> {
+    let session_id = ctx.session_id.as_deref()
+        .ok_or_else(|| CommandError::new("NO_SESSION", "No active session"))?;
+
+    let topics = handler
+        .store
+        .list_topics(session_id)
+        .map_err(|e| CommandError::new("LIST_TOPICS_ERROR", e.to_string()))?;
+
+    let current_topic_id = ctx.topic_id.as_deref().unwrap_or("");
+
+    let message = if topics.is_empty() {
+        "No topics found. Use /new <title> to create a topic.".to_string()
+    } else {
+        let mut lines = vec![format!("Found {} topic(s):", topics.len())];
+        lines.push(String::new());
+        lines.push("┌────┬─────────────────┬──────────────────────┬──────────┬─────────────────┐".to_string());
+        lines.push("│ No │ Topic ID        │ Title                │ Messages │ Last Active     │".to_string());
+        lines.push("├────┼─────────────────┼──────────────────────┼──────────┼─────────────────┤".to_string());
+
+        for (idx, topic) in topics.iter().enumerate() {
+            let row_num = idx + 1;
+            let is_current = topic.id == current_topic_id;
+            let num_marker = if is_current { " * ".to_string() } else { format!(" {:<2}", row_num) };
+
+            let topic_id_display = if topic.id.len() > 15 {
+                format!("{}...", &topic.id[..12])
+            } else {
+                topic.id.clone()
+            };
+            let title_display = if topic.title.len() > 20 {
+                format!("{}...", &topic.title[..17])
+            } else {
+                topic.title.clone()
+            };
+
+            let last_active = format_time_ago(topic.last_active_at);
+
+            lines.push(format!(
+                "│{}│ {:<15} │ {:<20} │ {:<8} │ {:<15} │",
+                num_marker,
+                topic_id_display,
+                title_display,
+                topic.message_count,
+                last_active
+            ));
+        }
+
+        lines.push("└────┴─────────────────┴──────────────────────┴──────────┴─────────────────┘".to_string());
+        lines.push(String::new());
+        lines.push("* = current topic".to_string());
+        lines.push("Use /use <number> or /use <topic_id> to switch".to_string());
+
+        lines.join("\n")
+    };
+
+    let topics_json = serde_json::to_string(&topics)
+        .map_err(|e| CommandError::new("SERIALIZE_ERROR", e.to_string()))?;
+
+    Ok(CommandResponse::success(ctx.request_id)
+        .with_message(MessageKind::Notification, &message)
+        .with_metadata("topics", &topics_json)
+        .with_metadata("count", &topics.len().to_string())
+        .with_metadata("current_topic_id", current_topic_id))
+}
+
+fn format_time_ago(timestamp_ms: i64) -> String {
+    let now = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap()
+        .as_millis() as i64;
+
+    let diff_ms = now - timestamp_ms;
+    let diff_secs = diff_ms / 1000;
+
+    if diff_secs < 60 {
+        "just now".to_string()
+    } else if diff_secs < 3600 {
+        format!("{} mins ago", diff_secs / 60)
+    } else if diff_secs < 86400 {
+        format!("{} hours ago", diff_secs / 3600)
+    } else {
+        format!("{} days ago", diff_secs / 86400)
+    }
+}

src/command/handlers/load_session.rs

@@ -0,0 +1,64 @@
+use crate::command::context::CommandContext;
+use crate::command::handler::{CommandHandler, CommandMetadata};
+use crate::command::response::{CommandError, CommandResponse, MessageKind};
+use crate::command::Command;
+use crate::storage::SessionStore;
+use async_trait::async_trait;
+use std::sync::Arc;
+
+/// 加载话题命令处理器
+pub struct LoadSessionCommandHandler {
+    store: Arc<SessionStore>,
+}
+
+impl LoadSessionCommandHandler {
+    pub fn new(store: Arc<SessionStore>) -> Self {
+        Self { store }
+    }
+}
+
+#[async_trait]
+impl CommandHandler for LoadSessionCommandHandler {
+    fn can_handle(&self, cmd: &Command) -> bool {
+        matches!(cmd, Command::LoadSession { .. })
+    }
+
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "load",
+            description: "加载指定话题",
+            usage: "/load <session_id>",
+        })
+    }
+
+    async fn handle(
+        &self,
+        cmd: Command,
+        ctx: CommandContext,
+    ) -> Result<CommandResponse, CommandError> {
+        match cmd {
+            Command::LoadSession { session_id } => {
+                handle_load_session(self, session_id, ctx).await
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+
+async fn handle_load_session(
+    handler: &LoadSessionCommandHandler,
+    topic_id: String,
+    ctx: CommandContext,
+) -> Result<CommandResponse, CommandError> {
+    let topic = handler
+        .store
+        .get_topic(&topic_id)
+        .map_err(|e| CommandError::new("LOAD_TOPIC_ERROR", e.to_string()))?
+        .ok_or_else(|| CommandError::new("TOPIC_NOT_FOUND", format!("Topic not found: {}", topic_id)))?;
+
+    Ok(CommandResponse::success(ctx.request_id)
+        .with_message(MessageKind::Notification, &topic.title)
+        .with_metadata("topic_id", &topic.id)
+        .with_metadata("title", &topic.title)
+        .with_metadata("message_count", &topic.message_count.to_string()))
+}

src/command/handlers/mod.rs

@@ -1,7 +1,11 @@
+pub mod get_current;
+pub mod help;
+pub mod list_sessions;
+pub mod load_session;
 pub mod save_session;
 pub mod save_topic;
 pub mod session;
-pub mod session_query;
+pub mod switch_session;
 
 // 导出公共函数供其他模块复用
 pub use save_session::{

src/command/handlers/save_session.rs

@@ -1,7 +1,7 @@
 use crate::agent::{SystemPrompt, SystemPromptContext, SystemPromptProvider};
 use crate::bus::InboundMessage;
 use crate::command::context::CommandContext;
-use crate::command::handler::{CommandHandler, InChatCommandHandler};
+use crate::command::handler::{CommandHandler, CommandMetadata, InChatCommandHandler};
 use crate::command::response::{CommandError, CommandResponse, MessageKind};
 use crate::command::Command;
 use crate::storage::{SessionRecord, SessionStore};
@@ -107,6 +107,14 @@ impl CommandHandler for SaveSessionCommandHandler {
         matches!(cmd, Command::SaveSession { .. })
     }
 
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "save-session",
+            description: "保存当前会话到 Markdown 文件",
+            usage: "/save-session [all] [filepath]",
+        })
+    }
+
     async fn handle(
         &self,
         cmd: Command,

src/command/handlers/save_topic.rs

@@ -1,6 +1,6 @@
 use crate::agent::{SystemPrompt, SystemPromptContext, SystemPromptProvider};
 use crate::command::context::CommandContext;
-use crate::command::handler::CommandHandler;
+use crate::command::handler::{CommandHandler, CommandMetadata};
 use crate::command::handlers::{
     escape_yaml_string, format_timestamp, generate_messages_markdown,
     generate_system_prompt_markdown,
@@ -176,6 +176,14 @@ impl CommandHandler for SaveTopicCommandHandler {
         matches!(cmd, Command::SaveTopic { .. })
     }
 
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "save",
+            description: "保存当前话题到 Markdown 文件",
+            usage: "/save [filepath]",
+        })
+    }
+
     async fn handle(
         &self,
         cmd: Command,

src/command/handlers/session.rs

@@ -1,5 +1,5 @@
 use crate::command::context::CommandContext;
-use crate::command::handler::CommandHandler;
+use crate::command::handler::{CommandHandler, CommandMetadata};
 use crate::command::response::{CommandError, CommandResponse, MessageKind};
 use crate::command::Command;
 use crate::gateway::session::SessionManager;
@@ -40,6 +40,14 @@ impl CommandHandler for SessionCommandHandler {
         matches!(cmd, Command::CreateSession { .. })
     }
 
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "new",
+            description: "创建新话题",
+            usage: "/new [title]",
+        })
+    }
+
     async fn handle(
         &self,
         cmd: Command,

src/command/handlers/session_query.rs

@@ -1,368 +0,0 @@
-use crate::command::context::CommandContext;
-use crate::command::handler::CommandHandler;
-use crate::command::response::{CommandError, CommandResponse, MessageKind};
-use crate::command::Command;
-use crate::gateway::session::SessionManager;
-use crate::storage::SessionStore;
-use async_trait::async_trait;
-use std::sync::Arc;
-
-/// 会话查询命令处理器
-///
-/// 处理 ListSessions、LoadSession 和 SwitchSession 命令（现在操作 Topic）
-pub struct SessionQueryCommandHandler {
-    store: Arc<SessionStore>,
-    session_manager: Option<SessionManager>,
-}
-
-impl SessionQueryCommandHandler {
-    /// 创建新的会话查询命令处理器
-    pub fn new(store: Arc<SessionStore>) -> Self {
-        Self {
-            store,
-            session_manager: None,
-        }
-    }
-
-    /// 设置 SessionManager（用于 SwitchSession 命令）
-    pub fn with_session_manager(mut self, session_manager: SessionManager) -> Self {
-        self.session_manager = Some(session_manager);
-        self
-    }
-}
-
-#[async_trait]
-impl CommandHandler for SessionQueryCommandHandler {
-    fn can_handle(&self, cmd: &Command) -> bool {
-        matches!(cmd, Command::ListSessions { .. } | Command::LoadSession { .. } | Command::SwitchSession { .. } | Command::GetCurrentSession)
-    }
-
-    async fn handle(
-        &self,
-        cmd: Command,
-        ctx: CommandContext,
-    ) -> Result<CommandResponse, CommandError> {
-        match cmd {
-            Command::ListSessions { include_archived } => {
-                handle_list_sessions(self, include_archived, ctx).await
-            }
-            Command::LoadSession { session_id } => {
-                handle_load_session(self, session_id, ctx).await
-            }
-            Command::SwitchSession { session_id } => {
-                handle_switch_session(self, session_id, ctx).await
-            }
-            Command::GetCurrentSession => {
-                handle_get_current_session(self, ctx).await
-            }
-            _ => unreachable!(),
-        }
-    }
-}
-
-/// 处理列出话题命令
-async fn handle_list_sessions(
-    handler: &SessionQueryCommandHandler,
-    _include_archived: bool,
-    ctx: CommandContext,
-) -> Result<CommandResponse, CommandError> {
-    // 获取当前 session_id
-    let session_id = ctx.session_id.as_deref()
-        .ok_or_else(|| CommandError::new("NO_SESSION", "No active session"))?;
-
-    // 查询该 session 的所有 topic
-    let topics = handler
-        .store
-        .list_topics(session_id)
-        .map_err(|e| CommandError::new("LIST_TOPICS_ERROR", e.to_string()))?;
-
-    // 获取当前 topic ID
-    let current_topic_id = ctx.topic_id.as_deref().unwrap_or("");
-
-    // 构建表格格式的话题列表消息
-    let message = if topics.is_empty() {
-        "No topics found. Use /new <title> to create a topic.".to_string()
-    } else {
-        let mut lines = vec![format!("Found {} topic(s):", topics.len())];
-        lines.push(String::new());
-
-        // 表格头部
-        lines.push("┌────┬─────────────────┬──────────────────────┬──────────┬─────────────────┐".to_string());
-        lines.push("│ No │ Topic ID        │ Title                │ Messages │ Last Active     │".to_string());
-        lines.push("├────┼─────────────────┼──────────────────────┼──────────┼─────────────────┤".to_string());
-
-        // 表格内容
-        for (idx, topic) in topics.iter().enumerate() {
-            let row_num = idx + 1;
-            let is_current = topic.id == current_topic_id;
-            let num_marker = if is_current { " * ".to_string() } else { format!(" {:<2}", row_num) };
-
-            // 截断过长的字段
-            let topic_id_display = if topic.id.len() > 15 {
-                format!("{}...", &topic.id[..12])
-            } else {
-                topic.id.clone()
-            };
-            let title_display = if topic.title.len() > 20 {
-                format!("{}...", &topic.title[..17])
-            } else {
-                topic.title.clone()
-            };
-
-            let last_active = format_time_ago(topic.last_active_at);
-
-            lines.push(format!(
-                "│{}│ {:<15} │ {:<20} │ {:<8} │ {:<15} │",
-                num_marker,
-                topic_id_display,
-                title_display,
-                topic.message_count,
-                last_active
-            ));
-        }
-
-        // 表格底部
-        lines.push("└────┴─────────────────┴──────────────────────┴──────────┴─────────────────┘".to_string());
-        lines.push(String::new());
-        lines.push("* = current topic".to_string());
-        lines.push("Use /use <number> or /use <topic_id> to switch".to_string());
-
-        lines.join("\n")
-    };
-
-    let topics_json = serde_json::to_string(&topics)
-        .map_err(|e| CommandError::new("SERIALIZE_ERROR", e.to_string()))?;
-
-    Ok(CommandResponse::success(ctx.request_id)
-        .with_message(MessageKind::Notification, &message)
-        .with_metadata("topics", &topics_json)
-        .with_metadata("count", &topics.len().to_string())
-        .with_metadata("current_topic_id", current_topic_id))
-}
-
-/// 处理加载话题命令
-async fn handle_load_session(
-    handler: &SessionQueryCommandHandler,
-    topic_id: String,
-    ctx: CommandContext,
-) -> Result<CommandResponse, CommandError> {
-    let topic = handler
-        .store
-        .get_topic(&topic_id)
-        .map_err(|e| CommandError::new("LOAD_TOPIC_ERROR", e.to_string()))?
-        .ok_or_else(|| CommandError::new("TOPIC_NOT_FOUND", format!("Topic not found: {}", topic_id)))?;
-
-    Ok(CommandResponse::success(ctx.request_id)
-        .with_message(MessageKind::Notification, &topic.title)
-        .with_metadata("topic_id", &topic.id)
-        .with_metadata("title", &topic.title)
-        .with_metadata("message_count", &topic.message_count.to_string()))
-}
-
-/// 格式化时间为相对时间（如 "2 mins ago"）
-fn format_time_ago(timestamp_ms: i64) -> String {
-    let now = std::time::SystemTime::now()
-        .duration_since(std::time::UNIX_EPOCH)
-        .unwrap()
-        .as_millis() as i64;
-
-    let diff_ms = now - timestamp_ms;
-    let diff_secs = diff_ms / 1000;
-
-    if diff_secs < 60 {
-        "just now".to_string()
-    } else if diff_secs < 3600 {
-        format!("{} mins ago", diff_secs / 60)
-    } else if diff_secs < 86400 {
-        format!("{} hours ago", diff_secs / 3600)
-    } else {
-        format!("{} days ago", diff_secs / 86400)
-    }
-}
-
-/// 处理获取当前话题命令
-async fn handle_get_current_session(
-    handler: &SessionQueryCommandHandler,
-    ctx: CommandContext,
-) -> Result<CommandResponse, CommandError> {
-    let topic_id = ctx.topic_id.as_deref()
-        .ok_or_else(|| CommandError::new("NO_CURRENT_TOPIC", "No current topic"))?;
-
-    let topic = handler
-        .store
-        .get_topic(topic_id)
-        .map_err(|e| CommandError::new("GET_TOPIC_ERROR", e.to_string()))?
-        .ok_or_else(|| CommandError::new("TOPIC_NOT_FOUND", format!("Topic not found: {}", topic_id)))?;
-
-    let last_active = format_time_ago(topic.last_active_at);
-    let created_at = format_time_ago(topic.created_at);
-
-    let message = format!(
-        "Current Topic:\n\n  Topic ID: {}\n  Title: {}\n  Messages: {}\n  Created: {}\n  Last Active: {}",
-        topic.id,
-        topic.title,
-        topic.message_count,
-        created_at,
-        last_active
-    );
-
-    Ok(CommandResponse::success(ctx.request_id)
-        .with_message(MessageKind::Notification, &message)
-        .with_metadata("topic_id", &topic.id)
-        .with_metadata("title", &topic.title)
-        .with_metadata("message_count", &topic.message_count.to_string()))
-}
-
-/// 处理切换话题命令
-async fn handle_switch_session(
-    handler: &SessionQueryCommandHandler,
-    topic_id: String,
-    ctx: CommandContext,
-) -> Result<CommandResponse, CommandError> {
-    // 获取当前 session_id 和 chat_id
-    let session_id = ctx.session_id.as_deref()
-        .ok_or_else(|| CommandError::new("NO_SESSION", "No active session"))?;
-    let chat_id = ctx.chat_id.as_deref()
-        .ok_or_else(|| CommandError::new("NO_CHAT_ID", "No chat_id in context"))?;
-
-    // 尝试解析为序号
-    let target_topic_id = if let Ok(index) = topic_id.parse::<usize>() {
-        let topics = handler
-            .store
-            .list_topics(session_id)
-            .map_err(|e| CommandError::new("LIST_TOPICS_ERROR", e.to_string()))?;
-
-        let index = index.saturating_sub(1);
-        if index >= topics.len() {
-            return Err(CommandError::new(
-                "INVALID_TOPIC_INDEX",
-                format!("Topic index {} is out of range (1-{})", index + 1, topics.len())
-            ));
-        }
-        topics[index].id.clone()
-    } else {
-        topic_id
-    };
-
-    // 验证目标话题存在
-    let topic = handler
-        .store
-        .get_topic(&target_topic_id)
-        .map_err(|e| CommandError::new("SWITCH_TOPIC_ERROR", e.to_string()))?
-        .ok_or_else(|| CommandError::new("TOPIC_NOT_FOUND", format!("Topic not found: {}", target_topic_id)))?;
-
-    // 如果有 SessionManager，实际切换话题历史
-    if let Some(ref session_manager) = handler.session_manager {
-        if let Some(session) = session_manager.get(&ctx.channel_name).await {
-            let mut session_guard = session.lock().await;
-            session_guard.switch_topic(chat_id, &target_topic_id)
-                .map_err(|e| CommandError::new("SWITCH_TOPIC_ERROR", e.to_string()))?;
-        }
-    }
-
-    // 返回切换成功响应
-    let message = format!(
-        "✓ Switched to topic: {} ({} messages)",
-        topic.title, topic.message_count
-    );
-
-    Ok(CommandResponse::success(ctx.request_id)
-        .with_message(MessageKind::Notification, &message)
-        .with_metadata("topic_id", &topic.id)
-        .with_metadata("title", &topic.title)
-        .with_metadata("message_count", &topic.message_count.to_string()))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use crate::storage::SessionStore;
-    use std::sync::Arc;
-
-    fn create_test_handler() -> SessionQueryCommandHandler {
-        let store = Arc::new(SessionStore::in_memory().unwrap());
-        SessionQueryCommandHandler::new(store)
-    }
-
-    #[tokio::test]
-    async fn test_list_sessions_empty() {
-        let handler = create_test_handler();
-        // 需要先创建一个 session 和 topic
-        let store = handler.store.clone();
-        let session = store.create_session("cli", Some("test")).unwrap();
-
-        let ctx = CommandContext::new("test", "cli")
-            .with_session_id(&session.id);
-        let cmd = Command::ListSessions {
-            include_archived: false,
-        };
-
-        let result = handler.handle(cmd, ctx).await;
-
-        assert!(result.is_ok());
-        let resp = result.unwrap();
-        assert!(resp.success);
-        assert!(resp.messages[0].content.contains("No topics"));
-    }
-
-    #[tokio::test]
-    async fn test_list_sessions_with_items() {
-        let handler = create_test_handler();
-        let store = handler.store.clone();
-        let session = store.create_session("cli", Some("test")).unwrap();
-
-        // 创建一个 topic
-        store.create_topic(&session.id, "Test Topic", None).unwrap();
-
-        let ctx = CommandContext::new("test", "cli")
-            .with_session_id(&session.id);
-        let cmd = Command::ListSessions {
-            include_archived: false,
-        };
-
-        let result = handler.handle(cmd, ctx).await;
-
-        assert!(result.is_ok());
-        let resp = result.unwrap();
-        assert!(resp.success);
-        assert!(resp.metadata.contains_key("topics"));
-    }
-
-    #[tokio::test]
-    async fn test_load_session_not_found() {
-        let handler = create_test_handler();
-        let store = handler.store.clone();
-        let session = store.create_session("cli", Some("test")).unwrap();
-
-        let ctx = CommandContext::new("test", "test")
-            .with_session_id(&session.id);
-        let cmd = Command::LoadSession {
-            session_id: "nonexistent".to_string(),
-        };
-
-        let result = handler.handle(cmd, ctx).await;
-
-        assert!(result.is_err());
-    }
-
-    #[tokio::test]
-    async fn test_load_session_success() {
-        let handler = create_test_handler();
-        let store = handler.store.clone();
-        let session = store.create_session("cli", Some("test")).unwrap();
-        let topic = store.create_topic(&session.id, "Test Topic", None).unwrap();
-
-        let ctx = CommandContext::new("test", "test")
-            .with_session_id(&session.id);
-        let cmd = Command::LoadSession {
-            session_id: topic.id.clone(),
-        };
-
-        let result = handler.handle(cmd, ctx).await;
-
-        assert!(result.is_ok());
-        let resp = result.unwrap();
-        assert!(resp.success);
-        assert_eq!(resp.metadata.get("topic_id").unwrap(), &topic.id);
-    }
-}

src/command/handlers/switch_session.rs

@@ -0,0 +1,130 @@
+use crate::command::context::CommandContext;
+use crate::command::handler::{CommandHandler, CommandMetadata};
+use crate::command::response::{CommandError, CommandResponse, MessageKind};
+use crate::command::Command;
+use crate::gateway::session::SessionManager;
+use crate::storage::SessionStore;
+use async_trait::async_trait;
+use std::sync::Arc;
+
+/// 切换话题命令处理器
+pub struct SwitchSessionCommandHandler {
+    store: Arc<SessionStore>,
+    session_manager: Option<SessionManager>,
+}
+
+impl SwitchSessionCommandHandler {
+    pub fn new(store: Arc<SessionStore>) -> Self {
+        Self { store, session_manager: None }
+    }
+
+    pub fn with_session_manager(mut self, session_manager: SessionManager) -> Self {
+        self.session_manager = Some(session_manager);
+        self
+    }
+}
+
+#[async_trait]
+impl CommandHandler for SwitchSessionCommandHandler {
+    fn can_handle(&self, cmd: &Command) -> bool {
+        matches!(cmd, Command::SwitchSession { .. })
+    }
+
+    fn metadata(&self) -> Option<CommandMetadata> {
+        Some(CommandMetadata {
+            name: "use",
+            description: "切换到指定话题",
+            usage: "/use <session_id>",
+        })
+    }
+
+    async fn handle(
+        &self,
+        cmd: Command,
+        ctx: CommandContext,
+    ) -> Result<CommandResponse, CommandError> {
+        match cmd {
+            Command::SwitchSession { session_id } => {
+                handle_switch_session(self, session_id, ctx).await
+            }
+            _ => unreachable!(),
+        }
+    }
+}
+
+async fn handle_switch_session(
+    handler: &SwitchSessionCommandHandler,
+    topic_id: String,
+    ctx: CommandContext,
+) -> Result<CommandResponse, CommandError> {
+    let session_id = ctx.session_id.as_deref()
+        .ok_or_else(|| CommandError::new("NO_SESSION", "No active session"))?;
+    let chat_id = ctx.chat_id.as_deref()
+        .ok_or_else(|| CommandError::new("NO_CHAT_ID", "No chat_id in context"))?;
+
+    // 尝试解析为序号
+    let target_topic_id = if let Ok(index) = topic_id.parse::<usize>() {
+        let topics = handler
+            .store
+            .list_topics(session_id)
+            .map_err(|e| CommandError::new("LIST_TOPICS_ERROR", e.to_string()))?;
+
+        let index = index.saturating_sub(1);
+        if index >= topics.len() {
+            return Err(CommandError::new(
+                "INVALID_TOPIC_INDEX",
+                format!("Topic index {} is out of range (1-{})", index + 1, topics.len())
+            ));
+        }
+        topics[index].id.clone()
+    } else {
+        topic_id
+    };
+
+    // 验证目标话题存在
+    let topic = handler
+        .store
+        .get_topic(&target_topic_id)
+        .map_err(|e| CommandError::new("SWITCH_TOPIC_ERROR", e.to_string()))?
+        .ok_or_else(|| CommandError::new("TOPIC_NOT_FOUND", format!("Topic not found: {}", target_topic_id)))?;
+
+    // 如果有 SessionManager，实际切换话题历史
+    if let Some(ref session_manager) = handler.session_manager {
+        if let Some(session) = session_manager.get(&ctx.channel_name).await {
+            let mut session_guard = session.lock().await;
+            session_guard.switch_topic(chat_id, &target_topic_id)
+                .map_err(|e| CommandError::new("SWITCH_TOPIC_ERROR", e.to_string()))?;
+        }
+    }
+
+    let message = format!(
+        "✓ Switched to topic: {} ({} messages)",
+        topic.title, topic.message_count
+    );
+
+    Ok(CommandResponse::success(ctx.request_id)
+        .with_message(MessageKind::Notification, &message)
+        .with_metadata("topic_id", &topic.id)
+        .with_metadata("title", &topic.title)
+        .with_metadata("message_count", &topic.message_count.to_string()))
+}
+
+fn format_time_ago(timestamp_ms: i64) -> String {
+    let now = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap()
+        .as_millis() as i64;
+
+    let diff_ms = now - timestamp_ms;
+    let diff_secs = diff_ms / 1000;
+
+    if diff_secs < 60 {
+        "just now".to_string()
+    } else if diff_secs < 3600 {
+        format!("{} mins ago", diff_secs / 60)
+    } else if diff_secs < 86400 {
+        format!("{} hours ago", diff_secs / 3600)
+    } else {
+        format!("{} days ago", diff_secs / 86400)
+    }
+}

src/command/mod.rs

@@ -28,6 +28,8 @@ pub enum Command {
     SwitchSession { session_id: String },
     /// 获取当前话题信息
     GetCurrentSession,
+    /// 显示所有支持的命令
+    Help,
 }
 
 impl Command {
@@ -41,6 +43,7 @@ impl Command {
             Command::LoadSession { .. } => "load_session",
             Command::SwitchSession { .. } => "switch_session",
             Command::GetCurrentSession => "get_current_session",
+            Command::Help => "help",
         }
     }
 }

src/gateway/processor.rs

@@ -7,10 +7,14 @@ use crate::bus::{InboundMessage, MessageBus, OutboundMessage};
 use crate::command::adapter::InputAdapter;
 use crate::command::adapters::channel::ChannelInputAdapter;
 use crate::command::handler::CommandRouter;
+use crate::command::handlers::get_current::GetCurrentSessionCommandHandler;
+use crate::command::handlers::help::HelpCommandHandler;
+use crate::command::handlers::list_sessions::ListSessionsCommandHandler;
+use crate::command::handlers::load_session::LoadSessionCommandHandler;
 use crate::command::handlers::save_session::SaveSessionCommandHandler;
 use crate::command::handlers::save_topic::SaveTopicCommandHandler;
 use crate::command::handlers::session::SessionCommandHandler;
-use crate::command::handlers::session_query::SessionQueryCommandHandler;
+use crate::command::handlers::switch_session::SwitchSessionCommandHandler;
 use crate::config::LLMProviderConfig;
 use crate::gateway::agent_prompt_provider::AgentPromptProvider;
 use crate::skills::SkillPromptProvider;
@@ -43,13 +47,21 @@ impl InboundProcessor {
             .with_session_manager(session_manager.clone());
         command_router.register(Box::new(session_handler));
 
-        // 注册 session_query 处理器
-        let session_query_handler = SessionQueryCommandHandler::new(store)
+        // 注册 list_sessions 处理器
+        command_router.register(Box::new(ListSessionsCommandHandler::new(store.clone())));
+
+        // 注册 switch_session 处理器
+        let switch_handler = SwitchSessionCommandHandler::new(store.clone())
             .with_session_manager(session_manager.clone());
-        command_router.register(Box::new(session_query_handler));
+        command_router.register(Box::new(switch_handler));
+
+        // 注册 get_current 处理器
+        command_router.register(Box::new(GetCurrentSessionCommandHandler::new(store.clone())));
+
+        // 注册 load_session 处理器
+        command_router.register(Box::new(LoadSessionCommandHandler::new(store.clone())));
 
         // 注册 save_session 处理器
-        let store = session_manager.store();
         let skills = session_manager.skills();
         let prompt_repository = session_manager.store().clone();
         let system_prompt_provider: Arc<dyn crate::agent::SystemPromptProvider> = Arc::new(CompositeSystemPromptProvider::new(vec![
@@ -67,10 +79,14 @@ impl InboundProcessor {
 
         // 注册 save_topic 处理器
         command_router.register(Box::new(SaveTopicCommandHandler::new(
-            store,
+            store.clone(),
             system_prompt_provider,
         )));
 
+        // 注册 help 处理器（最后注册，获取所有已注册命令的元数据）
+        let metadata = command_router.metadata_arc();
+        command_router.register(Box::new(HelpCommandHandler::new(metadata)));
+
         Self {
             bus,
             session_manager,

src/gateway/ws.rs

@@ -5,9 +5,13 @@ use crate::command::adapter::{InputAdapter, OutputAdapter};
 use crate::command::adapters::websocket::{WebSocketInputAdapter, WebSocketOutputAdapter};
 use crate::command::context::CommandContext;
 use crate::command::handler::CommandRouter;
+use crate::command::handlers::get_current::GetCurrentSessionCommandHandler;
+use crate::command::handlers::help::HelpCommandHandler;
+use crate::command::handlers::list_sessions::ListSessionsCommandHandler;
+use crate::command::handlers::load_session::LoadSessionCommandHandler;
 use crate::command::handlers::save_session::SaveSessionCommandHandler;
 use crate::command::handlers::session::SessionCommandHandler;
-use crate::command::handlers::session_query::SessionQueryCommandHandler;
+use crate::command::handlers::switch_session::SwitchSessionCommandHandler;
 use crate::gateway::agent_prompt_provider::AgentPromptProvider;
 use crate::protocol::{WsInbound, WsOutbound, parse_inbound, serialize_outbound};
 use crate::skills::SkillPromptProvider;
@@ -224,18 +228,27 @@ async fn handle_inbound(
             ]));
 
             let mut router = CommandRouter::new();
-            // 注册 Session 处理器，添加 SessionManager
+            // 注册 Session 处理器
             let session_handler = SessionCommandHandler::new(store.clone())
                 .with_session_manager(state.session_manager.clone());
             router.register(Box::new(session_handler));
-            // 注册 SessionQuery 处理器
-            let session_query_handler = SessionQueryCommandHandler::new(store.clone())
+            // 注册 list_sessions 处理器
+            router.register(Box::new(ListSessionsCommandHandler::new(store.clone())));
+            // 注册 switch_session 处理器
+            let switch_handler = SwitchSessionCommandHandler::new(store.clone())
                 .with_session_manager(state.session_manager.clone());
-            router.register(Box::new(session_query_handler));
+            router.register(Box::new(switch_handler));
+            // 注册 get_current 处理器
+            router.register(Box::new(GetCurrentSessionCommandHandler::new(store.clone())));
+            // 注册 load_session 处理器
+            router.register(Box::new(LoadSessionCommandHandler::new(store.clone())));
             router.register(Box::new(SaveSessionCommandHandler::new(
-                store,
-                system_prompt_provider,
+                store.clone(),
+                system_prompt_provider.clone(),
             )));
+            // 注册 help 处理器
+            let metadata = router.metadata_arc();
+            router.register(Box::new(HelpCommandHandler::new(metadata)));
 
             // 构建命令上下文
             tracing::debug!(