diff --git a/pom.xml b/pom.xml
index c7c56af..44a42fa 100644
--- a/pom.xml
+++ b/pom.xml
@@ -9,8 +9,8 @@
     <version>1.0-SNAPSHOT</version>
 
     <properties>
-        <maven.compiler.source>25</maven.compiler.source>
-        <maven.compiler.target>25</maven.compiler.target>
+        <maven.compiler.source>21</maven.compiler.source>
+        <maven.compiler.target>21</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
diff --git a/src/main/java/com/university/chat/Server/ClientSession.java b/src/main/java/com/university/chat/Server/ClientSession.java
index 864fb87..f0c79a4 100644
--- a/src/main/java/com/university/chat/Server/ClientSession.java
+++ b/src/main/java/com/university/chat/Server/ClientSession.java
@@ -2,18 +2,33 @@ package com.university.chat.Server;
 
 import com.university.chat.Common.ChatMessage;
 import com.university.chat.Common.FileMessage;
+import com.university.chat.Common.MessageType;
 
 import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.net.Socket;
 import java.nio.file.Files;
 
 public class ClientSession implements Runnable {
 
     private String username;
+    private Socket socket;
+    private UserManager userManager;
+    private ObjectOutputStream out;
+    private ObjectInputStream in;
 
     public ClientSession(Socket socket, UserManager userManager) {
-        // TODO : Create an ObjectOutputStream from socket.getOutputStream()
-        //         and an ObjectInputStream from socket.getInputStream().
+
+        this.socket = socket;
+        this.userManager = userManager;
+        try {
+            this.out = new ObjectOutputStream(socket.getOutputStream());
+            this.in = new ObjectInputStream(socket.getInputStream());
+        }
+        catch (IOException e) {
+            System.out.println("Failed to create streams: "  + e.getMessage());
+        }
 
     }
 
@@ -21,28 +36,49 @@ public class ClientSession implements Runnable {
     public void run() {
         try {
 
-            // TODO: Welcome the user (login step)
-            //  1. Read the first object sent by the client.
-            //  2. Check it's a ChatMessage with type LOGIN.
-            //  3. Extract the username.
-            //  4. Try to register the user via userManager.addUser(...).
-            //  5. If the username is taken, send back LOGIN_FAILED and close the socket.
-            //  6. Otherwise, create the user's folders with FileManager.createUserFolders(...)
-            //      and send back LOGIN_SUCCESS.
+            Object firstObject = in.readObject();
+            if (!(firstObject instanceof ChatMessage loginMsg) || loginMsg.getType() != MessageType.LOGIN) {
+                socket.close();
+                return;
+            }
+            username = loginMsg.getSender();
 
-            // TODO: Main message loop
-            //   In a loop, call in.readObject(), you can separate messages by their type:
-            //     - if it's a ChatMessage      -> call handleChatMessage(msg)
-            //     - if it's a FileMessage      -> call handleFileMessage(fileMsg)
-            //   Keep looping until the connection is closed (an exception will be thrown).
+            boolean registered = userManager.addUser(username,this);
+
+            if (!registered) {
+                sendMessage(new ChatMessage(MessageType.LOGIN_FAILED, "Server", username, "Username already taken."));
+                socket.close();
+                return;
+            }
+            FileManager.createUserFolders(username);
+            sendMessage(new ChatMessage(MessageType.LOGIN_SUCCESS, "Server", username, "Welcome " + username + "!"));
+            System.out.println(username + " logged in successfully.");
+
+            while(true) {
+                Object message = in.readObject();
+                if  (message instanceof FileMessage msg) {
+                    handleFileMessage(msg);
+                }
+                else if  (message instanceof ChatMessage msg) {
+                    handleChatMessage(msg);
+                }
+            }
 
         } catch (Exception e) {
             System.out.println("Disconnected: " + username);
         } finally {
-            // TODO: Remove the user from UserManager so they no longer
-            //        receive broadcasts or appear in users list
+            if (username != null) {
+                userManager.removeUser(username);
+            }
+            try {
+                socket.close();
+            }catch (IOException e) {}
         }
     }
+    public synchronized void sendMessage(Object obj) throws IOException {
+        out.writeObject(obj);
+        out.flush();
+    }
 
 
     private void handleChatMessage(ChatMessage msg) throws IOException {