feat: 添加会话消息发送工具，支持文本和附件的发送，优化消息发送逻辑

src/channels/feishu.rs

@@ -523,7 +523,7 @@ impl FeishuChannel {
 
         let resp = self
             .http_client
-            .post(format!("{}/im/v1/images/upload", FEISHU_API_BASE))
+            .post(format!("{}/im/v1/images", FEISHU_API_BASE))
             .header("Authorization", format!("Bearer {}", token))
             .multipart(form)
             .send()
@@ -543,10 +543,18 @@ impl FeishuChannel {
             image_key: String,
         }
 
-        let result: UploadResp = resp
+        let status = resp.status();
-            .json()
+        let body = resp.text().await.map_err(|e| {
-            .await
+            ChannelError::Other(format!("Read upload image response error: {}", e))
-            .map_err(|e| ChannelError::Other(format!("Parse upload response error: {}", e)))?;
+        })?;
+        let result: UploadResp = serde_json::from_str(&body).map_err(|e| {
+            ChannelError::Other(format!(
+                "Parse upload image response error: {} (status={}, body={})",
+                e,
+                status,
+                truncate_with_ellipsis(&body, 500)
+            ))
+        })?;
 
         if result.code != 0 {
             return Err(ChannelError::Other(format!(
@@ -578,10 +586,10 @@ impl FeishuChannel {
             .to_lowercase();
 
         let file_type = match extension.as_str() {
-            "mp3" | "m4a" | "wav" | "ogg" => "audio",
+            "mp3" | "m4a" | "wav" | "ogg" | "opus" => "opus",
             "mp4" | "mov" | "avi" | "mkv" => "video",
             "pdf" | "doc" | "docx" | "xls" | "xlsx" => "doc",
-            _ => "file",
+            _ => "stream",
         };
 
         let file_data = tokio::fs::read(file_path)
@@ -618,10 +626,18 @@ impl FeishuChannel {
             file_key: String,
         }
 
-        let result: UploadResp = resp
+        let status = resp.status();
-            .json()
+        let body = resp.text().await.map_err(|e| {
-            .await
+            ChannelError::Other(format!("Read upload file response error: {}", e))
-            .map_err(|e| ChannelError::Other(format!("Parse upload response error: {}", e)))?;
+        })?;
+        let result: UploadResp = serde_json::from_str(&body).map_err(|e| {
+            ChannelError::Other(format!(
+                "Parse upload file response error: {} (status={}, body={})",
+                e,
+                status,
+                truncate_with_ellipsis(&body, 500)
+            ))
+        })?;
 
         if result.code != 0 {
             return Err(ChannelError::Other(format!(
@@ -2348,13 +2364,17 @@ impl Channel for FeishuChannel {
             "open_id"
         };
 
+        let remove_reaction = async {
+            self.remove_reaction_from_metadata(&msg.metadata).await;
+        };
+
         // If no media, use smart format detection
         if msg.media.is_empty() {
             let content = msg.content.trim();
 
             // Empty content
             if content.is_empty() {
-                self.remove_reaction_from_metadata(&msg.metadata).await;
+                remove_reaction.await;
                 return Ok(());
             }
 
@@ -2366,7 +2386,7 @@ impl Channel for FeishuChannel {
                     let result = self
                         .send_message_to_feishu(receive_id, receive_id_type, "text", content)
                         .await;
-                    self.remove_reaction_from_metadata(&msg.metadata).await;
+                    remove_reaction.await;
                     return result;
                 }
                 MsgFormat::Post => {
@@ -2375,7 +2395,7 @@ impl Channel for FeishuChannel {
                     let result = self
                         .send_message_to_feishu(receive_id, receive_id_type, "post", &post_body)
                         .await;
-                    self.remove_reaction_from_metadata(&msg.metadata).await;
+                    remove_reaction.await;
                     return result;
                 }
                 MsgFormat::Interactive => {
@@ -2400,134 +2420,68 @@ impl Channel for FeishuChannel {
                                     content,
                                 )
                                 .await;
-                            self.remove_reaction_from_metadata(&msg.metadata).await;
+                            remove_reaction.await;
                             return result;
                         }
                     }
-                    self.remove_reaction_from_metadata(&msg.metadata).await;
+                    remove_reaction.await;
                     return Ok(());
                 }
             }
         }
 
-        // Handle multimodal message - send with media
+        if !msg.content.trim().is_empty() {
-        let token = self.get_tenant_access_token().await?;
+            self.send_message_to_feishu(receive_id, receive_id_type, "text", msg.content.trim())
-
+                .await?;
-        // Build content with media references
-        let mut content_parts = Vec::new();
-
-        // Add text content if present (truncate if too long for Feishu)
-        if !msg.content.is_empty() {
-            const MAX_TEXT_LENGTH: usize = 60_000;
-            let truncated_text = if msg.content.len() > MAX_TEXT_LENGTH {
-                format!(
-                    "{}...\n\n[Content truncated due to length limit]",
-                    &msg.content[..MAX_TEXT_LENGTH]
-                )
-            } else {
-                msg.content.clone()
-            };
-            content_parts.push(serde_json::json!({
-                "tag": "text",
-                "text": truncated_text
-            }));
         }
 
-        // Upload and add media
+        let mut sent_media = 0usize;
         for media_item in &msg.media {
             let path = &media_item.path;
-            match media_item.media_type.as_str() {
+            let result = match media_item.media_type.as_str() {
-                "image" => match self.upload_image(path).await {
+                "image" => {
-                    Ok(image_key) => {
+                    let image_key = self.upload_image(path).await?;
-                        content_parts.push(serde_json::json!({
+                    self.send_message_to_feishu(
-                            "tag": "image",
+                        receive_id,
-                            "image_key": image_key
+                        receive_id_type,
-                        }));
+                        "image",
+                        &serde_json::json!({ "image_key": image_key }).to_string(),
+                    )
+                    .await
                 }
-                    Err(e) => {
+                "audio" | "file" | "video" => {
-                        tracing::warn!(error = %e, path = %path, "Failed to upload image");
+                    let file_key = self.upload_file(path).await?;
+                    self.send_message_to_feishu(
+                        receive_id,
+                        receive_id_type,
+                        "file",
+                        &serde_json::json!({ "file_key": file_key }).to_string(),
+                    )
+                    .await
                 }
-                },
-                "audio" | "file" | "video" => match self.upload_file(path).await {
-                    Ok(file_key) => {
-                        content_parts.push(serde_json::json!({
-                            "tag": "file",
-                            "file_key": file_key
-                        }));
-                    }
-                    Err(e) => {
-                        tracing::warn!(error = %e, path = %path, "Failed to upload file");
-                    }
-                },
                 _ => {
                     tracing::warn!(media_type = %media_item.media_type, "Unsupported media type for sending");
+                    continue;
                 }
-            }
-        }
-
-        // If no content parts after processing, just send empty text
-        if content_parts.is_empty() {
-            let result = self
-                .send_message_to_feishu(receive_id, receive_id_type, "text", "")
-                .await;
-            // Remove pending reaction after sending (using metadata propagated from inbound)
-            self.remove_reaction_from_metadata(&msg.metadata).await;
-            return result;
-        }
-
-        // Determine message type
-        let has_image = msg.media.iter().any(|m| m.media_type == "image");
-        let msg_type = if has_image && msg.content.is_empty() {
-            "image"
-        } else {
-            "post"
             };
 
-        let content = serde_json::json!({
+            match result {
-            "content": content_parts
+                Ok(()) => sent_media += 1,
-        })
+                Err(error) => {
-        .to_string();
+                    tracing::warn!(error = %error, path = %path, media_type = %media_item.media_type, "Failed to send media message to Feishu");
-
+                    return Err(error);
-        let resp = self
+                }
-            .http_client
+            }
-            .post(format!(
-                "{}/im/v1/messages?receive_id_type={}",
-                FEISHU_API_BASE, receive_id_type
-            ))
-            .header("Content-Type", "application/json")
-            .header("Authorization", format!("Bearer {}", token))
-            .json(&serde_json::json!({
-                "receive_id": receive_id,
-                "msg_type": msg_type,
-                "content": content
-            }))
-            .send()
-            .await
-            .map_err(|e| {
-                ChannelError::ConnectionError(format!("Send multimodal message HTTP error: {}", e))
-            })?;
-
-        #[derive(Deserialize)]
-        struct SendResp {
-            code: i32,
-            msg: String,
         }
 
-        let send_resp: SendResp = resp
+        if msg.content.trim().is_empty() && sent_media == 0 {
-            .json()
+            remove_reaction.await;
-            .await
+            return Err(ChannelError::Other(
-            .map_err(|e| ChannelError::Other(format!("Parse send response error: {}", e)))?;
+                "No supported media items were sent to Feishu".to_string(),
-
+            ));
-        if send_resp.code != 0 {
-            return Err(ChannelError::Other(format!(
-                "Send multimodal message failed: code={} msg={}",
-                send_resp.code, send_resp.msg
-            )));
         }
 
-        // Remove pending reaction after successfully sending
+        remove_reaction.await;
-        self.remove_reaction_from_metadata(&msg.metadata).await;
-
         Ok(())
     }
 }

src/gateway/mod.rs

@@ -19,6 +19,7 @@ pub mod session;
 pub mod session_factory;
 pub mod session_history;
 pub mod session_lifecycle;
+pub mod session_message_sender;
 pub mod session_message_service;
 pub mod session_pool;
 pub mod tool_registry_factory;
@@ -39,7 +40,8 @@ use crate::skills::SkillRuntime;
 use agent_task_executor::{AgentTaskExecutor, SchedulerMaintenanceService};
 use outbound_dispatcher::OutboundDispatcher;
 use processor::InboundProcessor;
-use runtime::build_session_manager;
+use runtime::build_session_manager_with_sender;
+use session_message_sender::BusSessionMessageSender;
 use session::SessionManager;
 
 pub struct GatewayState {
@@ -64,8 +66,10 @@ impl GatewayState {
         let show_tool_results = config.gateway.show_tool_results;
 
         let skills = Arc::new(SkillRuntime::from_config(config.skills.clone()));
+        let channel_manager = ChannelManager::new();
+        let bus = channel_manager.bus();
 
-        let session_manager = build_session_manager(
+        let session_manager = build_session_manager_with_sender(
             session_ttl_hours,
             agent_prompt_reinject_every,
             show_tool_results,
@@ -73,9 +77,8 @@ impl GatewayState {
             provider_config,
             provider_configs,
             skills,
+            Arc::new(BusSessionMessageSender::new(bus.clone())),
         )?;
-        let channel_manager = ChannelManager::new();
-        let bus = channel_manager.bus();
 
         Ok(Self {
             config,

src/gateway/runtime.rs

@@ -8,7 +8,7 @@ use crate::storage::{
     ConversationRepository, MemoryRepository, PromptInjectionRepository, SchedulerJobRepository,
     SessionStore, SkillEventRepository,
 };
-use crate::tools::ToolRegistry;
+use crate::tools::{NoopSessionMessageSender, SessionMessageSender, ToolRegistry};
 
 use super::agent_factory::AgentFactory;
 use super::cli_session::CliSessionService;
@@ -30,6 +30,28 @@ pub(crate) fn build_session_manager(
     provider_config: LLMProviderConfig,
     provider_configs: HashMap<String, LLMProviderConfig>,
     skills: Arc<SkillRuntime>,
+) -> Result<SessionManager, AgentError> {
+    build_session_manager_with_sender(
+        session_ttl_hours,
+        agent_prompt_reinject_every,
+        show_tool_results,
+        default_timezone,
+        provider_config,
+        provider_configs,
+        skills,
+        Arc::new(NoopSessionMessageSender),
+    )
+}
+
+pub(crate) fn build_session_manager_with_sender(
+    session_ttl_hours: u64,
+    agent_prompt_reinject_every: u64,
+    show_tool_results: bool,
+    default_timezone: String,
+    provider_config: LLMProviderConfig,
+    provider_configs: HashMap<String, LLMProviderConfig>,
+    skills: Arc<SkillRuntime>,
+    session_message_sender: Arc<dyn SessionMessageSender>,
 ) -> Result<SessionManager, AgentError> {
     let store = Arc::new(
         SessionStore::new()
@@ -53,6 +75,7 @@ pub(crate) fn build_session_manager(
             memories,
             scheduler_jobs,
             skill_events.clone(),
+            session_message_sender,
             known_agents,
             default_timezone,
         )

src/gateway/session.rs

@@ -496,6 +496,7 @@ mod tests {
     use crate::bus::MessageBus;
     use crate::gateway::tool_registry_factory::ToolRegistryFactory;
     use crate::storage::MemoryRecord;
+    use crate::tools::NoopSessionMessageSender;
     use axum::http::StatusCode;
     use axum::{Json, Router, routing::post};
     use serde_json::{Value, json};
@@ -537,6 +538,7 @@ mod tests {
                 store.clone(),
                 store.clone(),
                 store.clone(),
+                Arc::new(NoopSessionMessageSender),
                 HashSet::new(),
                 "Asia/Shanghai".to_string(),
             )
@@ -581,6 +583,7 @@ mod tests {
                 store.clone(),
                 store.clone(),
                 store.clone(),
+                Arc::new(NoopSessionMessageSender),
                 HashSet::new(),
                 "Asia/Shanghai".to_string(),
             )
@@ -1483,6 +1486,7 @@ mod tests {
                 store.clone(),
                 store.clone(),
                 store.clone(),
+                Arc::new(NoopSessionMessageSender),
                 HashSet::new(),
                 "Asia/Shanghai".to_string(),
             )
@@ -1520,6 +1524,7 @@ mod tests {
                 store.clone(),
                 store.clone(),
                 store.clone(),
+                Arc::new(NoopSessionMessageSender),
                 HashSet::new(),
                 "Asia/Shanghai".to_string(),
             )
@@ -1585,6 +1590,7 @@ mod tests {
                 store.clone(),
                 store.clone(),
                 store.clone(),
+                Arc::new(NoopSessionMessageSender),
                 HashSet::new(),
                 "Asia/Shanghai".to_string(),
             )
@@ -1632,6 +1638,7 @@ mod tests {
             store.clone(),
             store.clone(),
             store,
+            Arc::new(NoopSessionMessageSender),
             HashSet::new(),
             "Asia/Shanghai".to_string(),
         )

src/gateway/session_message_sender.rs

@@ -0,0 +1,123 @@
+use std::collections::HashMap;
+use std::sync::Arc;
+
+use async_trait::async_trait;
+
+use crate::bus::{MessageBus, OutboundMessage};
+use crate::tools::{SessionMessageSender, SessionSendOutcome, SessionSendRequest, ToolContext};
+
+pub(crate) struct BusSessionMessageSender {
+    bus: Arc<MessageBus>,
+}
+
+impl BusSessionMessageSender {
+    pub(crate) fn new(bus: Arc<MessageBus>) -> Self {
+        Self { bus }
+    }
+}
+
+#[async_trait]
+impl SessionMessageSender for BusSessionMessageSender {
+    async fn send_to_current_session(
+        &self,
+        context: &ToolContext,
+        request: SessionSendRequest,
+    ) -> anyhow::Result<SessionSendOutcome> {
+        let channel_name = context
+            .channel_name
+            .as_deref()
+            .ok_or_else(|| anyhow::anyhow!("missing channel_name in tool context"))?;
+        let chat_id = context
+            .chat_id
+            .as_deref()
+            .ok_or_else(|| anyhow::anyhow!("missing chat_id in tool context"))?;
+
+        let metadata = HashMap::new();
+        let mut published_messages = 0;
+        let text_sent = request
+            .text
+            .as_deref()
+            .map(str::trim)
+            .filter(|text| !text.is_empty())
+            .is_some();
+
+        if let Some(text) = request.text.filter(|value| !value.trim().is_empty()) {
+            self.bus
+                .publish_outbound(OutboundMessage::assistant(
+                    channel_name.to_string(),
+                    chat_id.to_string(),
+                    text,
+                    None,
+                    metadata.clone(),
+                ))
+                .await?;
+            published_messages += 1;
+        }
+
+        let attachment_count = request.attachments.len();
+        for attachment in request.attachments {
+            let mut outbound = OutboundMessage::assistant(
+                channel_name.to_string(),
+                chat_id.to_string(),
+                String::new(),
+                None,
+                metadata.clone(),
+            );
+            outbound.media = vec![attachment];
+            self.bus.publish_outbound(outbound).await?;
+            published_messages += 1;
+        }
+
+        Ok(SessionSendOutcome {
+            published_messages,
+            text_sent,
+            attachment_count,
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::bus::MediaItem;
+
+    #[tokio::test]
+    async fn bus_sender_publishes_text_then_attachment() {
+        let bus = MessageBus::new(8);
+        let sender = BusSessionMessageSender::new(bus.clone());
+        let context = ToolContext {
+            channel_name: Some("feishu".to_string()),
+            chat_id: Some("chat-1".to_string()),
+            ..ToolContext::default()
+        };
+
+        let outcome = sender
+            .send_to_current_session(
+                &context,
+                SessionSendRequest {
+                    text: Some("hello".to_string()),
+                    attachments: vec![MediaItem::new("/tmp/demo.png", "image")],
+                },
+            )
+            .await
+            .unwrap();
+
+        assert_eq!(
+            outcome,
+            SessionSendOutcome {
+                published_messages: 2,
+                text_sent: true,
+                attachment_count: 1,
+            }
+        );
+
+        let first = bus.consume_outbound().await;
+        assert_eq!(first.content, "hello");
+        assert!(first.media.is_empty());
+
+        let second = bus.consume_outbound().await;
+        assert_eq!(second.content, "");
+        assert_eq!(second.media.len(), 1);
+        assert_eq!(second.media[0].media_type, "image");
+    }
+}

src/gateway/tool_registry_factory.rs

@@ -5,8 +5,9 @@ use crate::skills::SkillRuntime;
 use crate::storage::{MemoryRepository, SchedulerJobRepository, SkillEventRepository};
 use crate::tools::{
     BashTool, CalculatorTool, FileEditTool, FileReadTool, FileWriteTool, HttpRequestTool,
-    MemoryManageTool, MemorySearchTool, SchedulerManageTool, SkillActivateTool, SkillListTool,
+    MemoryManageTool, MemorySearchTool, SchedulerManageTool, SessionMessageSender,
-    SkillManageTool, TimeTool, ToolRegistry, WebFetchTool,
+    SessionSendTool, SkillActivateTool, SkillListTool, SkillManageTool, TimeTool, ToolRegistry,
+    WebFetchTool,
 };
 
 pub(crate) struct ToolRegistryFactory {
@@ -14,6 +15,7 @@ pub(crate) struct ToolRegistryFactory {
     memories: Arc<dyn MemoryRepository>,
     scheduler_jobs: Arc<dyn SchedulerJobRepository>,
     skill_events: Arc<dyn SkillEventRepository>,
+    session_message_sender: Arc<dyn SessionMessageSender>,
     known_agents: HashSet<String>,
     default_timezone: String,
 }
@@ -24,6 +26,7 @@ impl ToolRegistryFactory {
         memories: Arc<dyn MemoryRepository>,
         scheduler_jobs: Arc<dyn SchedulerJobRepository>,
         skill_events: Arc<dyn SkillEventRepository>,
+        session_message_sender: Arc<dyn SessionMessageSender>,
         known_agents: HashSet<String>,
         default_timezone: String,
     ) -> Self {
@@ -32,6 +35,7 @@ impl ToolRegistryFactory {
             memories,
             scheduler_jobs,
             skill_events,
+            session_message_sender,
             known_agents,
             default_timezone,
         }
@@ -46,6 +50,7 @@ impl ToolRegistryFactory {
         registry.register(FileEditTool::new());
         registry.register(MemorySearchTool::new(self.memories.clone()));
         registry.register(MemoryManageTool::new(self.memories.clone()));
+        registry.register(SessionSendTool::new(self.session_message_sender.clone()));
         registry.register(SchedulerManageTool::new(
             self.scheduler_jobs.clone(),
             self.known_agents.clone(),

src/tools/mod.rs

@@ -8,6 +8,7 @@ pub mod memory_manage;
 pub mod memory_search;
 pub mod registry;
 pub mod scheduler_manage;
+pub mod session_send;
 pub mod schema;
 pub mod skill_activate;
 pub mod skill_manage;
@@ -25,6 +26,10 @@ pub use memory_manage::MemoryManageTool;
 pub use memory_search::MemorySearchTool;
 pub use registry::ToolRegistry;
 pub use scheduler_manage::SchedulerManageTool;
+pub use session_send::{
+	NoopSessionMessageSender, SessionMessageSender, SessionSendOutcome, SessionSendRequest,
+	SessionSendTool,
+};
 pub use schema::{CleaningStrategy, SchemaCleanr};
 pub use skill_activate::SkillActivateTool;
 pub use skill_manage::{SkillListTool, SkillManageTool};

src/tools/session_send.rs

@@ -0,0 +1,320 @@
+use std::path::Path;
+use std::sync::Arc;
+
+use anyhow::anyhow;
+use async_trait::async_trait;
+use serde_json::json;
+
+use crate::bus::MediaItem;
+
+use super::traits::{Tool, ToolContext, ToolResult};
+
+#[derive(Debug, Clone)]
+pub struct SessionSendRequest {
+    pub text: Option<String>,
+    pub attachments: Vec<MediaItem>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct SessionSendOutcome {
+    pub published_messages: usize,
+    pub text_sent: bool,
+    pub attachment_count: usize,
+}
+
+#[async_trait]
+pub trait SessionMessageSender: Send + Sync + 'static {
+    async fn send_to_current_session(
+        &self,
+        context: &ToolContext,
+        request: SessionSendRequest,
+    ) -> anyhow::Result<SessionSendOutcome>;
+}
+
+pub struct NoopSessionMessageSender;
+
+#[async_trait]
+impl SessionMessageSender for NoopSessionMessageSender {
+    async fn send_to_current_session(
+        &self,
+        _context: &ToolContext,
+        _request: SessionSendRequest,
+    ) -> anyhow::Result<SessionSendOutcome> {
+        Err(anyhow!(
+            "session send tool is not configured with an outbound sender"
+        ))
+    }
+}
+
+pub struct SessionSendTool {
+    sender: Arc<dyn SessionMessageSender>,
+}
+
+impl SessionSendTool {
+    pub fn new(sender: Arc<dyn SessionMessageSender>) -> Self {
+        Self { sender }
+    }
+}
+
+#[async_trait]
+impl Tool for SessionSendTool {
+    fn name(&self) -> &str {
+        "send_session_message"
+    }
+
+    fn description(&self) -> &str {
+        "Send a message to the current conversation through the normal channel reply path. You can send a text-only message, one or more local file attachments, or a text message followed by attachments. Use this when you need to proactively deliver content back to the current user."
+    }
+
+    fn parameters_schema(&self) -> serde_json::Value {
+        json!({
+            "type": "object",
+            "properties": {
+                "text": {
+                    "type": "string",
+                    "description": "Optional text to send to the current conversation. This tool can send a text-only message even when no attachments are provided."
+                },
+                "attachments": {
+                    "type": "array",
+                    "description": "Optional list of local file paths to send to the current conversation.",
+                    "items": {
+                        "type": "string",
+                        "description": "Absolute or workspace-relative local file path"
+                    }
+                }
+            },
+            "anyOf": [
+                { "required": ["text"] },
+                { "required": ["attachments"] }
+            ]
+        })
+    }
+
+    async fn execute(&self, _args: serde_json::Value) -> anyhow::Result<ToolResult> {
+        Ok(error_result(
+            "send_session_message requires tool context for the current conversation",
+        ))
+    }
+
+    async fn execute_with_context(
+        &self,
+        context: &ToolContext,
+        args: serde_json::Value,
+    ) -> anyhow::Result<ToolResult> {
+        if let Err(err) = validate_context(context) {
+            return Ok(error_result(&err.to_string()));
+        }
+
+        let text = args
+            .get("text")
+            .and_then(|value| value.as_str())
+            .map(str::trim)
+            .filter(|value| !value.is_empty())
+            .map(ToOwned::to_owned);
+
+        let attachments = match args.get("attachments") {
+            Some(value) => match parse_attachments(value) {
+                Ok(attachments) => attachments,
+                Err(err) => return Ok(error_result(&err.to_string())),
+            },
+            None => Vec::new(),
+        };
+
+        if text.is_none() && attachments.is_empty() {
+            return Ok(error_result(
+                "send_session_message requires non-empty text, attachments, or both",
+            ));
+        }
+
+        let outcome = match self
+            .sender
+            .send_to_current_session(
+                context,
+                SessionSendRequest {
+                    text,
+                    attachments,
+                },
+            )
+            .await
+        {
+            Ok(outcome) => outcome,
+            Err(err) => return Ok(error_result(&err.to_string())),
+        };
+
+        Ok(ToolResult {
+            success: true,
+            output: format_success(outcome),
+            error: None,
+        })
+    }
+}
+
+fn validate_context(context: &ToolContext) -> anyhow::Result<()> {
+    if context.channel_name.as_deref().unwrap_or_default().is_empty() {
+        return Err(anyhow!(
+            "send_session_message requires channel_name in tool context"
+        ));
+    }
+    if context.chat_id.as_deref().unwrap_or_default().is_empty() {
+        return Err(anyhow!(
+            "send_session_message requires chat_id in tool context"
+        ));
+    }
+    Ok(())
+}
+
+fn parse_attachments(value: &serde_json::Value) -> anyhow::Result<Vec<MediaItem>> {
+    let attachment_paths = value
+        .as_array()
+        .ok_or_else(|| anyhow!("attachments must be an array of local file paths"))?;
+
+    let mut attachments = Vec::with_capacity(attachment_paths.len());
+    for path_value in attachment_paths {
+        let raw_path = path_value
+            .as_str()
+            .ok_or_else(|| anyhow!("attachments entries must be strings"))?
+            .trim();
+        if raw_path.is_empty() {
+            return Err(anyhow!("attachment paths must not be empty"));
+        }
+
+        let metadata = std::fs::metadata(raw_path)
+            .map_err(|err| anyhow!("failed to access attachment '{}': {}", raw_path, err))?;
+        if !metadata.is_file() {
+            return Err(anyhow!("attachment path is not a file: {}", raw_path));
+        }
+        if metadata.len() == 0 {
+            return Err(anyhow!("attachment file is empty: {}", raw_path));
+        }
+
+        let media_type = infer_media_type(raw_path);
+        let mut item = MediaItem::new(raw_path.to_string(), media_type);
+        item.mime_type = mime_guess::from_path(raw_path)
+            .first_raw()
+            .map(ToOwned::to_owned);
+        attachments.push(item);
+    }
+
+    Ok(attachments)
+}
+
+fn infer_media_type(path: &str) -> &'static str {
+    let mime = mime_guess::from_path(path).first_or_octet_stream();
+    if mime.essence_str().starts_with("image/") {
+        return "image";
+    }
+
+    match Path::new(path)
+        .extension()
+        .and_then(|ext| ext.to_str())
+        .map(|ext| ext.to_ascii_lowercase())
+        .as_deref()
+    {
+        Some("mp3") | Some("wav") | Some("ogg") | Some("m4a") | Some("opus") => "audio",
+        Some("mp4") | Some("mov") | Some("avi") | Some("mkv") => "video",
+        _ => "file",
+    }
+}
+
+fn format_success(outcome: SessionSendOutcome) -> String {
+    match (outcome.text_sent, outcome.attachment_count) {
+        (true, 0) => "Sent 1 text message to the current conversation.".to_string(),
+        (false, count) => format!("Sent {} attachment(s) to the current conversation.", count),
+        (true, count) => format!(
+            "Sent 1 text message and {} attachment(s) to the current conversation.",
+            count
+        ),
+    }
+}
+
+fn error_result(message: &str) -> ToolResult {
+    ToolResult {
+        success: false,
+        output: String::new(),
+        error: Some(message.to_string()),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::NamedTempFile;
+
+    struct MockSender {
+        outcome: SessionSendOutcome,
+    }
+
+    #[async_trait]
+    impl SessionMessageSender for MockSender {
+        async fn send_to_current_session(
+            &self,
+            _context: &ToolContext,
+            _request: SessionSendRequest,
+        ) -> anyhow::Result<SessionSendOutcome> {
+            Ok(self.outcome)
+        }
+    }
+
+    fn context() -> ToolContext {
+        ToolContext {
+            channel_name: Some("feishu".to_string()),
+            chat_id: Some("chat-1".to_string()),
+            ..ToolContext::default()
+        }
+    }
+
+    #[tokio::test]
+    async fn send_session_message_supports_text_only() {
+        let tool = SessionSendTool::new(Arc::new(MockSender {
+            outcome: SessionSendOutcome {
+                published_messages: 1,
+                text_sent: true,
+                attachment_count: 0,
+            },
+        }));
+
+        let result = tool
+            .execute_with_context(&context(), json!({ "text": "hello" }))
+            .await
+            .unwrap();
+
+        assert!(result.success);
+        assert_eq!(result.output, "Sent 1 text message to the current conversation.");
+    }
+
+    #[tokio::test]
+    async fn send_session_message_rejects_empty_request() {
+        let tool = SessionSendTool::new(Arc::new(MockSender {
+            outcome: SessionSendOutcome {
+                published_messages: 0,
+                text_sent: false,
+                attachment_count: 0,
+            },
+        }));
+
+        let result = tool
+            .execute_with_context(&context(), json!({}))
+            .await
+            .unwrap();
+
+        assert!(!result.success);
+        assert_eq!(
+            result.error.as_deref(),
+            Some("send_session_message requires non-empty text, attachments, or both")
+        );
+    }
+
+    #[test]
+    fn parse_attachments_infers_image_media_type() {
+        let file = NamedTempFile::new().unwrap();
+        std::fs::write(file.path(), b"demo").unwrap();
+        let image_path = file.path().with_extension("png");
+        std::fs::rename(file.path(), &image_path).unwrap();
+
+        let attachments = parse_attachments(&json!([image_path.to_string_lossy().to_string()]))
+            .unwrap();
+
+        assert_eq!(attachments.len(), 1);
+        assert_eq!(attachments[0].media_type, "image");
+    }
+}