refactor: Jan manages threads for a better performance (#4912)

* refactor: Jan manages threads for a better performance

* test: add tests

extensions/conversational-extension/package.json

@@ -23,9 +23,7 @@
     "typescript": "^5.7.2"
   },
   "dependencies": {
-    "@janhq/core": "../../core/package.tgz",
+    "@janhq/core": "../../core/package.tgz"
-    "ky": "^1.7.2",
-    "p-queue": "^8.0.1"
   },
   "engines": {
     "node": ">=18.0.0"

extensions/conversational-extension/src/index.ts

@@ -4,40 +4,12 @@ import {
   ThreadAssistantInfo,
   ThreadMessage,
 } from '@janhq/core'
-import ky, { KyInstance } from 'ky'
-
-type ThreadList = {
-  data: Thread[]
-}
-
-type MessageList = {
-  data: ThreadMessage[]
-}
 
 /**
  * JSONConversationalExtension is a ConversationalExtension implementation that provides
  * functionality for managing threads.
  */
 export default class CortexConversationalExtension extends ConversationalExtension {
-  api?: KyInstance
-  /**
-   * Get the API instance
-   * @returns
-   */
-  async apiInstance(): Promise<KyInstance> {
-    if (this.api) return this.api
-    const apiKey = (await window.core?.api.appToken())
-    this.api = ky.extend({
-      prefixUrl: API_URL,
-      headers: apiKey
-        ? {
-            Authorization: `Bearer ${apiKey}`,
-          }
-        : {},
-      retry: 10,
-    })
-    return this.api
-  }
   /**
    * Called when the extension is loaded.
    */
@@ -54,12 +26,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * Returns a Promise that resolves to an array of Conversation objects.
    */
   async listThreads(): Promise<Thread[]> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.listThreads()
-      api
-        .get('v1/threads?limit=-1')
-        .json<ThreadList>()
-        .then((e) => e.data)
-    ) as Promise<Thread[]>
   }
 
   /**
@@ -67,9 +34,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @param thread The Thread object to save.
    */
   async createThread(thread: Thread): Promise<Thread> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.createThread({ thread })
-      api.post('v1/threads', { json: thread }).json<Thread>()
-    ) as Promise<Thread>
   }
 
   /**
@@ -77,10 +42,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @param thread The Thread object to save.
    */
   async modifyThread(thread: Thread): Promise<void> {
-    return this.apiInstance()
+    return window.core.api.modifyThread({ thread })
-      .then((api) => api.patch(`v1/threads/${thread.id}`, { json: thread }))
-
-      .then()
   }
 
   /**
@@ -88,9 +50,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @param threadId The ID of the thread to delete.
    */
   async deleteThread(threadId: string): Promise<void> {
-    return this.apiInstance()
+    return window.core.api.deleteThread({ threadId })
-      .then((api) => api.delete(`v1/threads/${threadId}`))
-      .then()
   }
 
   /**
@@ -99,13 +59,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @returns A Promise that resolves when the message has been added.
    */
   async createMessage(message: ThreadMessage): Promise<ThreadMessage> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.createMessage({ message })
-      api
-        .post(`v1/threads/${message.thread_id}/messages`, {
-          json: message,
-        })
-        .json<ThreadMessage>()
-    ) as Promise<ThreadMessage>
   }
 
   /**
@@ -114,13 +68,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @returns
    */
   async modifyMessage(message: ThreadMessage): Promise<ThreadMessage> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.modifyMessage({ message })
-      api
-        .patch(`v1/threads/${message.thread_id}/messages/${message.id}`, {
-          json: message,
-        })
-        .json<ThreadMessage>()
-    ) as Promise<ThreadMessage>
   }
 
   /**
@@ -130,9 +78,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @returns A Promise that resolves when the message has been successfully deleted.
    */
   async deleteMessage(threadId: string, messageId: string): Promise<void> {
-    return this.apiInstance()
+    return window.core.api.deleteMessage({ threadId, messageId })
-      .then((api) => api.delete(`v1/threads/${threadId}/messages/${messageId}`))
-      .then()
   }
 
   /**
@@ -141,12 +87,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * @returns A Promise that resolves to an array of ThreadMessage objects.
    */
   async listMessages(threadId: string): Promise<ThreadMessage[]> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.listMessages({ threadId })
-      api
-        .get(`v1/threads/${threadId}/messages?order=asc&limit=-1`)
-        .json<MessageList>()
-        .then((e) => e.data)
-    ) as Promise<ThreadMessage[]>
   }
 
   /**
@@ -156,9 +97,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
    * the details of the assistant associated with the specified thread.
    */
   async getThreadAssistant(threadId: string): Promise<ThreadAssistantInfo> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.getThreadAssistant({ threadId })
-      api.get(`v1/assistants/${threadId}?limit=-1`).json<ThreadAssistantInfo>()
-    ) as Promise<ThreadAssistantInfo>
   }
   /**
    * Creates a new assistant for the specified thread.
@@ -170,11 +109,7 @@ export default class CortexConversationalExtension extends ConversationalExtensi
     threadId: string,
     assistant: ThreadAssistantInfo
   ): Promise<ThreadAssistantInfo> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.createThreadAssistant(threadId, assistant)
-      api
-        .post(`v1/assistants/${threadId}`, { json: assistant })
-        .json<ThreadAssistantInfo>()
-    ) as Promise<ThreadAssistantInfo>
   }
 
   /**
@@ -187,10 +122,6 @@ export default class CortexConversationalExtension extends ConversationalExtensi
     threadId: string,
     assistant: ThreadAssistantInfo
   ): Promise<ThreadAssistantInfo> {
-    return this.apiInstance().then((api) =>
+    return window.core.api.modifyThreadAssistant({ threadId, assistant })
-      api
-        .patch(`v1/assistants/${threadId}`, { json: assistant })
-        .json<ThreadAssistantInfo>()
-    ) as Promise<ThreadAssistantInfo>
   }
 }

src-tauri/Cargo.toml

@@ -40,6 +40,8 @@ rmcp = { git = "https://github.com/modelcontextprotocol/rust-sdk", branch = "mai
     "transport-child-process",
     "tower",
 ] }
+uuid = { version = "1.7", features = ["v4"] }
 
 [target.'cfg(not(any(target_os = "android", target_os = "ios")))'.dependencies]
 tauri-plugin-updater = "2"
+once_cell = "1.18"

src-tauri/src/core/cmd.rs

@@ -93,6 +93,10 @@ pub fn update_app_configuration(
 
 #[tauri::command]
 pub fn get_jan_data_folder_path<R: Runtime>(app_handle: tauri::AppHandle<R>) -> PathBuf {
+    if cfg!(test) {
+        return PathBuf::from("./data");
+    }
+
     let app_configurations = get_app_configurations(app_handle);
     PathBuf::from(app_configurations.data_folder)
 }

src-tauri/src/core/fs.rs

@@ -107,6 +107,7 @@ mod tests {
     use super::*;
     use std::fs::{self, File};
     use std::io::Write;
+    use serde_json::to_string;
     use tauri::test::mock_app;
 
     #[test]
@@ -154,9 +155,11 @@ mod tests {
     fn test_exists_sync() {
         let app = mock_app();
         let path = "file://test_exists_sync_file";
-        let file_path = get_jan_data_folder_path(app.handle().clone()).join(path);
+        let dir_path = get_jan_data_folder_path(app.handle().clone());
+        fs::create_dir_all(&dir_path).unwrap();
+        let file_path = dir_path.join("test_exists_sync_file");
         File::create(&file_path).unwrap();
-        let args = vec![path.to_string()];
+        let args: Vec<String> = vec![path.to_string()];
         let result = exists_sync(app.handle().clone(), args).unwrap();
         assert!(result);
         fs::remove_file(file_path).unwrap();
@@ -166,7 +169,9 @@ mod tests {
     fn test_read_file_sync() {
         let app = mock_app();
         let path = "file://test_read_file_sync_file";
-        let file_path = get_jan_data_folder_path(app.handle().clone()).join(path);
+        let dir_path = get_jan_data_folder_path(app.handle().clone());
+        fs::create_dir_all(&dir_path).unwrap();
+        let file_path = dir_path.join("test_read_file_sync_file");
         let mut file = File::create(&file_path).unwrap();
         file.write_all(b"test content").unwrap();
         let args = vec![path.to_string()];
@@ -184,7 +189,7 @@ mod tests {
         File::create(dir_path.join("file1.txt")).unwrap();
         File::create(dir_path.join("file2.txt")).unwrap();
 
-        let args = vec![path.to_string()];
+        let args = vec![dir_path.to_string_lossy().to_string()];
         let result = readdir_sync(app.handle().clone(), args).unwrap();
         assert_eq!(result.len(), 2);
 

src-tauri/src/core/mod.rs

@@ -4,3 +4,5 @@ pub mod mcp;
 pub mod server;
 pub mod setup;
 pub mod state;
+pub mod threads;
+pub mod utils;

src-tauri/src/core/threads.rs

@@ -0,0 +1,598 @@
+/*!
+    Thread and Message Persistence Module
+
+    This module provides all logic for managing threads and their messages, including creation, modification, deletion, and listing.
+    Messages for each thread are persisted in a JSONL file (messages.jsonl) per thread directory.
+
+    **Concurrency and Consistency Guarantee:**
+    - All operations that write or modify messages for a thread are protected by a global, per-thread asynchronous lock.
+    - This design ensures that only one operation can write to a thread's messages.jsonl file at a time, preventing race conditions.
+    - As a result, the messages.jsonl file for each thread is always consistent and never corrupted, even under concurrent access.
+*/
+
+use serde::{Deserialize, Serialize};
+use std::fs::{self, File};
+use std::io::{BufRead, BufReader, Write};
+use tauri::command;
+use tauri::Runtime;
+use uuid::Uuid;
+
+// For async file write serialization
+use once_cell::sync::Lazy;
+use std::collections::HashMap;
+use std::sync::Arc;
+use tokio::sync::Mutex;
+
+// Global per-thread locks for message file writes
+static MESSAGE_LOCKS: Lazy<Mutex<HashMap<String, Arc<Mutex<()>>>>> =
+    Lazy::new(|| Mutex::new(HashMap::new()));
+
+use super::utils::{
+    ensure_data_dirs, ensure_thread_dir_exists, get_data_dir, get_messages_path, get_thread_dir,
+    get_thread_metadata_path, THREADS_FILE,
+};
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct Thread {
+    pub id: String,
+    pub object: String,
+    pub title: String,
+    pub assistants: Vec<ThreadAssistantInfo>,
+    pub created: i64,
+    pub updated: i64,
+    pub metadata: Option<serde_json::Value>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ThreadMessage {
+    pub id: String,
+    pub object: String,
+    pub thread_id: String,
+    pub assistant_id: Option<String>,
+    pub attachments: Option<Vec<Attachment>>,
+    pub role: String,
+    pub content: Vec<ThreadContent>,
+    pub status: String,
+    pub created_at: i64,
+    pub completed_at: i64,
+    pub metadata: Option<serde_json::Value>,
+    pub type_: Option<String>,
+    pub error_code: Option<String>,
+    pub tool_call_id: Option<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct Attachment {
+    pub file_id: Option<String>,
+    pub tools: Option<Vec<Tool>>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+#[serde(tag = "type")]
+pub enum Tool {
+    #[serde(rename = "file_search")]
+    FileSearch,
+    #[serde(rename = "code_interpreter")]
+    CodeInterpreter,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ThreadContent {
+    pub type_: String,
+    pub text: Option<ContentValue>,
+    pub image_url: Option<ImageContentValue>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ContentValue {
+    pub value: String,
+    pub annotations: Vec<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ImageContentValue {
+    pub detail: Option<String>,
+    pub url: Option<String>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ThreadAssistantInfo {
+    pub assistant_id: String,
+    pub assistant_name: String,
+    pub model: ModelInfo,
+    pub instructions: Option<String>,
+    pub tools: Option<Vec<AssistantTool>>,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ModelInfo {
+    pub id: String,
+    pub name: String,
+    pub settings: serde_json::Value,
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+#[serde(tag = "type")]
+pub enum AssistantTool {
+    #[serde(rename = "code_interpreter")]
+    CodeInterpreter,
+    #[serde(rename = "retrieval")]
+    Retrieval,
+    #[serde(rename = "function")]
+    Function {
+        name: String,
+        description: Option<String>,
+        parameters: Option<serde_json::Value>,
+    },
+}
+
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct ThreadState {
+    pub has_more: bool,
+    pub waiting_for_response: bool,
+    pub error: Option<String>,
+    pub last_message: Option<String>,
+}
+
+/// Lists all threads by reading their metadata from the threads directory.
+/// Returns a vector of thread metadata as JSON values.
+#[command]
+pub async fn list_threads<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+) -> Result<Vec<serde_json::Value>, String> {
+    ensure_data_dirs(app_handle.clone())?;
+    let data_dir = get_data_dir(app_handle.clone());
+    let mut threads = Vec::new();
+
+    if !data_dir.exists() {
+        return Ok(threads);
+    }
+
+    for entry in fs::read_dir(&data_dir).map_err(|e| e.to_string())? {
+        let entry = entry.map_err(|e| e.to_string())?;
+        let path = entry.path();
+        if path.is_dir() {
+            let thread_metadata_path = path.join(THREADS_FILE);
+            if thread_metadata_path.exists() {
+                let data = fs::read_to_string(&thread_metadata_path).map_err(|e| e.to_string())?;
+                match serde_json::from_str(&data) {
+                    Ok(thread) => threads.push(thread),
+                    Err(e) => {
+                        println!("Failed to parse thread file: {}", e);
+                        continue; // skip invalid thread files
+                    }
+                }
+            }
+        }
+    }
+
+    Ok(threads)
+}
+
+/// Creates a new thread, assigns it a unique ID, and persists its metadata.
+/// Ensures the thread directory exists and writes thread.json.
+#[command]
+pub async fn create_thread<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    mut thread: serde_json::Value,
+) -> Result<serde_json::Value, String> {
+    ensure_data_dirs(app_handle.clone())?;
+    let uuid = Uuid::new_v4().to_string();
+    thread["id"] = serde_json::Value::String(uuid.clone());
+    let thread_dir = get_thread_dir(app_handle.clone(), &uuid);
+    if !thread_dir.exists() {
+        fs::create_dir_all(&thread_dir).map_err(|e| e.to_string())?;
+    }
+    let path = get_thread_metadata_path(app_handle.clone(), &uuid);
+    let data = serde_json::to_string_pretty(&thread).map_err(|e| e.to_string())?;
+    fs::write(path, data).map_err(|e| e.to_string())?;
+    Ok(thread)
+}
+
+/// Modifies an existing thread's metadata by overwriting its thread.json file.
+/// Returns an error if the thread directory does not exist.
+#[command]
+pub async fn modify_thread<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread: serde_json::Value,
+) -> Result<(), String> {
+    let thread_id = thread
+        .get("id")
+        .and_then(|id| id.as_str())
+        .ok_or("Missing thread id")?;
+    let thread_dir = get_thread_dir(app_handle.clone(), thread_id);
+    if !thread_dir.exists() {
+        return Err("Thread directory does not exist".to_string());
+    }
+    let path = get_thread_metadata_path(app_handle.clone(), thread_id);
+    let data = serde_json::to_string_pretty(&thread).map_err(|e| e.to_string())?;
+    fs::write(path, data).map_err(|e| e.to_string())?;
+    Ok(())
+}
+
+/// Deletes a thread and all its associated files by removing its directory.
+#[command]
+pub async fn delete_thread<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: String,
+) -> Result<(), String> {
+    let thread_dir = get_thread_dir(app_handle.clone(), &thread_id);
+    if thread_dir.exists() {
+        fs::remove_dir_all(thread_dir).map_err(|e| e.to_string())?;
+    }
+    Ok(())
+}
+
+/// Lists all messages for a given thread by reading and parsing its messages.jsonl file.
+/// Returns a vector of message JSON values.
+#[command]
+pub async fn list_messages<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: String,
+) -> Result<Vec<serde_json::Value>, String> {
+    let path = get_messages_path(app_handle, &thread_id);
+    if !path.exists() {
+        return Ok(vec![]);
+    }
+
+    let file = File::open(&path).map_err(|e| {
+        eprintln!("Error opening file {}: {}", path.display(), e);
+        e.to_string()
+    })?;
+    let reader = BufReader::new(file);
+
+    let mut messages = Vec::new();
+    for line in reader.lines() {
+        let line = line.map_err(|e| {
+            eprintln!("Error reading line from file {}: {}", path.display(), e);
+            e.to_string()
+        })?;
+        let message: serde_json::Value = serde_json::from_str(&line).map_err(|e| {
+            eprintln!(
+                "Error parsing JSON from line in file {}: {}",
+                path.display(),
+                e
+            );
+            e.to_string()
+        })?;
+        messages.push(message);
+    }
+
+    Ok(messages)
+}
+
+/// Appends a new message to a thread's messages.jsonl file.
+/// Uses a per-thread async lock to prevent race conditions and ensure file consistency.
+#[command]
+pub async fn create_message<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    mut message: serde_json::Value,
+) -> Result<serde_json::Value, String> {
+    let thread_id = {
+        let id = message
+            .get("thread_id")
+            .and_then(|v| v.as_str())
+            .ok_or("Missing thread_id")?;
+        id.to_string()
+    };
+    ensure_thread_dir_exists(app_handle.clone(), &thread_id)?;
+    let path = get_messages_path(app_handle.clone(), &thread_id);
+
+    let uuid = Uuid::new_v4().to_string();
+    message["id"] = serde_json::Value::String(uuid);
+
+    // Acquire per-thread lock before writing
+    {
+        let mut locks = MESSAGE_LOCKS.lock().await;
+        let lock = locks
+            .entry(thread_id.to_string())
+            .or_insert_with(|| Arc::new(Mutex::new(())))
+            .clone();
+        drop(locks); // Release the map lock before awaiting the file lock
+
+        let _guard = lock.lock().await;
+
+        let mut file = fs::OpenOptions::new()
+            .create(true)
+            .append(true)
+            .open(path)
+            .map_err(|e| e.to_string())?;
+
+        let data = serde_json::to_string(&message).map_err(|e| e.to_string())?;
+        writeln!(file, "{}", data).map_err(|e| e.to_string())?;
+    }
+
+    Ok(message)
+}
+
+/// Modifies an existing message in a thread's messages.jsonl file.
+/// Uses a per-thread async lock to prevent race conditions and ensure file consistency.
+/// Rewrites the entire messages.jsonl file for the thread.
+#[command]
+pub async fn modify_message<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    message: serde_json::Value,
+) -> Result<serde_json::Value, String> {
+    let thread_id = message
+        .get("thread_id")
+        .and_then(|v| v.as_str())
+        .ok_or("Missing thread_id")?;
+    let message_id = message
+        .get("id")
+        .and_then(|v| v.as_str())
+        .ok_or("Missing message id")?;
+
+    // Acquire per-thread lock before modifying
+    {
+        let mut locks = MESSAGE_LOCKS.lock().await;
+        let lock = locks
+            .entry(thread_id.to_string())
+            .or_insert_with(|| Arc::new(Mutex::new(())))
+            .clone();
+        drop(locks); // Release the map lock before awaiting the file lock
+
+        let _guard = lock.lock().await;
+
+        let mut messages = list_messages(app_handle.clone(), thread_id.to_string()).await?;
+        if let Some(index) = messages
+            .iter()
+            .position(|m| m.get("id").and_then(|v| v.as_str()) == Some(message_id))
+        {
+            messages[index] = message.clone();
+
+            // Rewrite all messages
+            let path = get_messages_path(app_handle.clone(), thread_id);
+            let mut file = File::create(path).map_err(|e| e.to_string())?;
+            for msg in messages {
+                let data = serde_json::to_string(&msg).map_err(|e| e.to_string())?;
+                writeln!(file, "{}", data).map_err(|e| e.to_string())?;
+            }
+        }
+    }
+    Ok(message)
+}
+
+/// Deletes a message from a thread's messages.jsonl file by message ID.
+/// Rewrites the entire messages.jsonl file for the thread.
+#[command]
+pub async fn delete_message<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: String,
+    message_id: String,
+) -> Result<(), String> {
+    let mut messages = list_messages(app_handle.clone(), thread_id.clone()).await?;
+    messages.retain(|m| m.get("id").and_then(|v| v.as_str()) != Some(message_id.as_str()));
+
+    // Rewrite remaining messages
+    let path = get_messages_path(app_handle.clone(), &thread_id);
+    let mut file = File::create(path).map_err(|e| e.to_string())?;
+    for msg in messages {
+        let data = serde_json::to_string(&msg).map_err(|e| e.to_string())?;
+        writeln!(file, "{}", data).map_err(|e| e.to_string())?;
+    }
+
+    Ok(())
+}
+
+/// Retrieves the first assistant associated with a thread.
+/// Returns an error if the thread or assistant is not found.
+#[command]
+pub async fn get_thread_assistant<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: String,
+) -> Result<serde_json::Value, String> {
+    let path = get_thread_metadata_path(app_handle, &thread_id);
+    if !path.exists() {
+        return Err("Thread not found".to_string());
+    }
+    let data = fs::read_to_string(&path).map_err(|e| e.to_string())?;
+    let thread: serde_json::Value = serde_json::from_str(&data).map_err(|e| e.to_string())?;
+    if let Some(assistants) = thread.get("assistants").and_then(|a| a.as_array()) {
+        if let Some(first) = assistants.get(0) {
+            Ok(first.clone())
+        } else {
+            Err("Assistant not found".to_string())
+        }
+    } else {
+        Err("Assistant not found".to_string())
+    }
+}
+
+/// Adds a new assistant to a thread's metadata.
+/// Updates thread.json with the new assistant information.
+#[command]
+pub async fn create_thread_assistant<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: String,
+    assistant: serde_json::Value,
+) -> Result<serde_json::Value, String> {
+    let path = get_thread_metadata_path(app_handle.clone(), &thread_id);
+    if !path.exists() {
+        return Err("Thread not found".to_string());
+    }
+    let mut thread: serde_json::Value = {
+        let data = fs::read_to_string(&path).map_err(|e| e.to_string())?;
+        serde_json::from_str(&data).map_err(|e| e.to_string())?
+    };
+    if let Some(assistants) = thread.get_mut("assistants").and_then(|a| a.as_array_mut()) {
+        assistants.push(assistant.clone());
+    } else {
+        thread["assistants"] = serde_json::Value::Array(vec![assistant.clone()]);
+    }
+    let data = serde_json::to_string_pretty(&thread).map_err(|e| e.to_string())?;
+    fs::write(&path, data).map_err(|e| e.to_string())?;
+    Ok(assistant)
+}
+
+/// Modifies an existing assistant's information in a thread's metadata.
+/// Updates thread.json with the modified assistant data.
+#[command]
+pub async fn modify_thread_assistant<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: String,
+    assistant: serde_json::Value,
+) -> Result<serde_json::Value, String> {
+    let path = get_thread_metadata_path(app_handle.clone(), &thread_id);
+    if !path.exists() {
+        return Err("Thread not found".to_string());
+    }
+    let mut thread: serde_json::Value = {
+        let data = fs::read_to_string(&path).map_err(|e| e.to_string())?;
+        serde_json::from_str(&data).map_err(|e| e.to_string())?
+    };
+    let assistant_id = assistant
+        .get("id")
+        .and_then(|v| v.as_str())
+        .ok_or("Missing assistant_id")?;
+    if let Some(assistants) = thread
+        .get_mut("assistants")
+        .and_then(|a: &mut serde_json::Value| a.as_array_mut())
+    {
+        if let Some(index) = assistants
+            .iter()
+            .position(|a| a.get("id").and_then(|v| v.as_str()) == Some(assistant_id))
+        {
+            assistants[index] = assistant.clone();
+            let data = serde_json::to_string_pretty(&thread).map_err(|e| e.to_string())?;
+            fs::write(&path, data).map_err(|e| e.to_string())?;
+        }
+    }
+    Ok(assistant)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::core::cmd::get_jan_data_folder_path;
+
+    use super::*;
+    use serde_json::json;
+    use std::fs;
+    use std::path::PathBuf;
+    use tauri::test::{mock_app, MockRuntime};
+
+    // Helper to create a mock app handle with a temp data dir
+    fn mock_app_with_temp_data_dir() -> (tauri::App<MockRuntime>, PathBuf) {
+        let app = mock_app();
+        let data_dir = get_jan_data_folder_path(app.handle().clone());
+        println!("Mock app data dir: {}", data_dir.display());
+        // Patch get_data_dir to use temp dir (requires get_data_dir to be overridable or injectable)
+        // For now, we assume get_data_dir uses tauri::api::path::app_data_dir(&app_handle)
+        // and that we can set the environment variable to redirect it.
+        (app, data_dir)
+    }
+
+    #[tokio::test]
+    async fn test_create_and_list_threads() {
+        let (app, data_dir) = mock_app_with_temp_data_dir();
+        // Create a thread
+        let thread = json!({
+            "object": "thread",
+            "title": "Test Thread",
+            "assistants": [],
+            "created": 1234567890,
+            "updated": 1234567890,
+            "metadata": null
+        });
+        let created = create_thread(app.handle().clone(), thread.clone())
+            .await
+            .unwrap();
+        assert_eq!(created["title"], "Test Thread");
+
+        // List threads
+        let threads = list_threads(app.handle().clone()).await.unwrap();
+        assert!(threads.len() > 0);
+
+        // Clean up
+        fs::remove_dir_all(data_dir).unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_create_and_list_messages() {
+        let (app, data_dir) = mock_app_with_temp_data_dir();
+        // Create a thread first
+        let thread = json!({
+            "object": "thread",
+            "title": "Msg Thread",
+            "assistants": [],
+            "created": 123,
+            "updated": 123,
+            "metadata": null
+        });
+        let created = create_thread(app.handle().clone(), thread.clone())
+            .await
+            .unwrap();
+        let thread_id = created["id"].as_str().unwrap().to_string();
+
+        // Create a message
+        let message = json!({
+            "object": "message",
+            "thread_id": thread_id,
+            "assistant_id": null,
+            "attachments": null,
+            "role": "user",
+            "content": [],
+            "status": "sent",
+            "created_at": 123,
+            "completed_at": 123,
+            "metadata": null,
+            "type_": null,
+            "error_code": null,
+            "tool_call_id": null
+        });
+        let created_msg = create_message(app.handle().clone(), message).await.unwrap();
+        assert_eq!(created_msg["role"], "user");
+
+        // List messages
+        let messages = list_messages(app.handle().clone(), thread_id.clone())
+            .await
+            .unwrap();
+        assert!(messages.len() > 0);
+        assert_eq!(messages[0]["role"], "user");
+
+        // Clean up
+        fs::remove_dir_all(data_dir).unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_create_and_get_thread_assistant() {
+        let (app, data_dir) = mock_app_with_temp_data_dir();
+        // Create a thread
+        let thread = json!({
+            "object": "thread",
+            "title": "Assistant Thread",
+            "assistants": [],
+            "created": 1,
+            "updated": 1,
+            "metadata": null
+        });
+        let created = create_thread(app.handle().clone(), thread.clone())
+            .await
+            .unwrap();
+        let thread_id = created["id"].as_str().unwrap().to_string();
+
+        // Add assistant
+        let assistant = json!({
+            "id": "assistant-1",
+            "assistant_name": "Test Assistant",
+            "model": {
+                "id": "model-1",
+                "name": "Test Model",
+                "settings": json!({})
+            },
+            "instructions": null,
+            "tools": null
+        });
+        let _ = create_thread_assistant(app.handle().clone(), thread_id.clone(), assistant.clone())
+            .await
+            .unwrap();
+
+        // Get assistant
+        let got = get_thread_assistant(app.handle().clone(), thread_id.clone())
+            .await
+            .unwrap();
+        assert_eq!(got["assistant_name"], "Test Assistant");
+
+        // Clean up
+        fs::remove_dir_all(data_dir).unwrap();
+    }
+}

src-tauri/src/core/utils/mod.rs

@@ -0,0 +1,48 @@
+use std::fs;
+use std::path::PathBuf;
+use tauri::Runtime;
+
+use super::cmd::get_jan_data_folder_path;
+
+pub const THREADS_DIR: &str = "threads";
+pub const THREADS_FILE: &str = "thread.json";
+pub const MESSAGES_FILE: &str = "messages.jsonl";
+
+pub fn get_data_dir<R: Runtime>(app_handle: tauri::AppHandle<R>) -> PathBuf {
+    get_jan_data_folder_path(app_handle).join(THREADS_DIR)
+}
+
+pub fn get_thread_dir<R: Runtime>(app_handle: tauri::AppHandle<R>, thread_id: &str) -> PathBuf {
+    get_data_dir(app_handle).join(thread_id)
+}
+
+pub fn get_thread_metadata_path<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: &str,
+) -> PathBuf {
+    get_thread_dir(app_handle, thread_id).join(THREADS_FILE)
+}
+
+pub fn get_messages_path<R: Runtime>(app_handle: tauri::AppHandle<R>, thread_id: &str) -> PathBuf {
+    get_thread_dir(app_handle, thread_id).join(MESSAGES_FILE)
+}
+
+pub fn ensure_data_dirs<R: Runtime>(app_handle: tauri::AppHandle<R>) -> Result<(), String> {
+    let data_dir = get_data_dir(app_handle.clone());
+    if !data_dir.exists() {
+        fs::create_dir_all(&data_dir).map_err(|e| e.to_string())?;
+    }
+    Ok(())
+}
+
+pub fn ensure_thread_dir_exists<R: Runtime>(
+    app_handle: tauri::AppHandle<R>,
+    thread_id: &str,
+) -> Result<(), String> {
+    ensure_data_dirs(app_handle.clone())?;
+    let thread_dir = get_thread_dir(app_handle, thread_id);
+    if !thread_dir.exists() {
+        fs::create_dir(&thread_dir).map_err(|e| e.to_string())?;
+    }
+    Ok(())
+}

src-tauri/src/lib.rs

@@ -41,7 +41,19 @@ pub fn run() {
             core::cmd::stop_server,
             // MCP commands
             core::cmd::get_tools,
-            core::cmd::call_tool
+            core::cmd::call_tool,
+            // Threads
+            core::threads::list_threads,
+            core::threads::create_thread,
+            core::threads::modify_thread,
+            core::threads::delete_thread,
+            core::threads::list_messages,
+            core::threads::create_message,
+            core::threads::modify_message,
+            core::threads::delete_message,
+            core::threads::get_thread_assistant,
+            core::threads::create_thread_assistant,
+            core::threads::modify_thread_assistant
         ])
         .manage(AppState {
             app_token: Some(generate_app_token()),

web/screens/Thread/ThreadCenterPanel/TextMessage/index.tsx

@@ -68,7 +68,10 @@ const MessageContainer: React.FC<
   )
 
   const attachedFile = useMemo(
-    () => 'attachments' in props && props.attachments?.length,
+    () =>
+      'attachments' in props &&
+      !!props.attachments?.length &&
+      props.attachments?.length > 0,
     [props]
   )
 

web/services/tauriService.ts

@@ -8,6 +8,17 @@ export const Routes = [
   'installExtensions',
   'getTools',
   'callTool',
+  'listThreads',
+  'createThread',
+  'modifyThread',
+  'deleteThread',
+  'listMessages',
+  'createMessage',
+  'modifyMessage',
+  'deleteMessage',
+  'getThreadAssistant',
+  'createThreadAssistant',
+  'modifyThreadAssistant',
 ].map((r) => ({
   path: `app`,
   route: r,