diff --git a/DysonNetwork.Sphere/Account/AccountService.cs b/DysonNetwork.Sphere/Account/AccountService.cs
index ba8ef5f..912d944 100644
--- a/DysonNetwork.Sphere/Account/AccountService.cs
+++ b/DysonNetwork.Sphere/Account/AccountService.cs
@@ -10,6 +10,8 @@ public class AccountService(AppDatabase db, PermissionService pm, IMemoryCache c
 {
     public async Task PurgeAccountCache(Account account)
     {
+        cache.Remove($"dyn_user_friends_{account.Id}");
+        
         var sessions = await db.AuthSessions.Where(e => e.Account.Id == account.Id).Select(e => e.Id)
             .ToListAsync();
         foreach (var session in sessions)
@@ -31,144 +33,4 @@ public class AccountService(AppDatabase db, PermissionService pm, IMemoryCache c
 
         return null;
     }
-
-    public async Task<bool> HasExistingRelationship(Account userA, Account userB)
-    {
-        var count = await db.AccountRelationships
-            .Where(r => (r.AccountId == userA.Id && r.AccountId == userB.Id) ||
-                        (r.AccountId == userB.Id && r.AccountId == userA.Id))
-            .CountAsync();
-        return count > 0;
-    }
-
-    public async Task<Relationship?> GetRelationship(
-        Account account,
-        Account related,
-        RelationshipStatus? status,
-        bool ignoreExpired = false
-    )
-    {
-        var now = Instant.FromDateTimeUtc(DateTime.UtcNow);
-        var queries = db.AccountRelationships
-            .Where(r => r.AccountId == account.Id && r.AccountId == related.Id);
-        if (ignoreExpired) queries = queries.Where(r => r.ExpiredAt > now);
-        if (status is not null) queries = queries.Where(r => r.Status == status);
-        var relationship = await queries.FirstOrDefaultAsync();
-        return relationship;
-    }
-
-    public async Task<Relationship> CreateRelationship(Account sender, Account target, RelationshipStatus status)
-    {
-        if (status == RelationshipStatus.Pending)
-            throw new InvalidOperationException(
-                "Cannot create relationship with pending status, use SendFriendRequest instead.");
-        if (await HasExistingRelationship(sender, target))
-            throw new InvalidOperationException("Found existing relationship between you and target user.");
-
-        var relationship = new Relationship
-        {
-            Account = sender,
-            AccountId = sender.Id,
-            Related = target,
-            RelatedId = target.Id,
-            Status = status
-        };
-
-        db.AccountRelationships.Add(relationship);
-        await db.SaveChangesAsync();
-        await ApplyRelationshipPermissions(relationship);
-
-        return relationship;
-    }
-
-    public async Task<Relationship> SendFriendRequest(Account sender, Account target)
-    {
-        if (await HasExistingRelationship(sender, target))
-            throw new InvalidOperationException("Found existing relationship between you and target user.");
-
-        var relationship = new Relationship
-        {
-            Account = sender,
-            AccountId = sender.Id,
-            Related = target,
-            RelatedId = target.Id,
-            Status = RelationshipStatus.Pending,
-            ExpiredAt = Instant.FromDateTimeUtc(DateTime.UtcNow.AddDays(7))
-        };
-
-        db.AccountRelationships.Add(relationship);
-        await db.SaveChangesAsync();
-
-        return relationship;
-    }
-
-    public async Task<Relationship> AcceptFriendRelationship(
-        Relationship relationship,
-        RelationshipStatus status = RelationshipStatus.Friends
-    )
-    {
-        if (relationship.Status == RelationshipStatus.Pending)
-            throw new ArgumentException("Cannot accept friend request by setting the new status to pending.");
-
-        // Whatever the receiver decides to apply which status to the relationship,
-        // the sender should always see the user as a friend since the sender ask for it
-        relationship.Status = RelationshipStatus.Friends;
-        relationship.ExpiredAt = null;
-        db.Update(relationship);
-
-        var relationshipBackward = new Relationship
-        {
-            Account = relationship.Related,
-            AccountId = relationship.RelatedId,
-            Related = relationship.Account,
-            RelatedId = relationship.AccountId,
-            Status = status
-        };
-        db.AccountRelationships.Add(relationshipBackward);
-
-        await db.SaveChangesAsync();
-
-        await Task.WhenAll(
-            ApplyRelationshipPermissions(relationship),
-            ApplyRelationshipPermissions(relationshipBackward)
-        );
-
-        return relationshipBackward;
-    }
-
-    public async Task<Relationship> UpdateRelationship(Account account, Account related, RelationshipStatus status)
-    {
-        var relationship = await GetRelationship(account, related, status);
-        if (relationship is null) throw new ArgumentException("There is no relationship between you and the user.");
-        if (relationship.Status == status) return relationship;
-        relationship.Status = status;
-        db.Update(relationship);
-        await db.SaveChangesAsync();
-        await ApplyRelationshipPermissions(relationship);
-        return relationship;
-    }
-
-    private async Task ApplyRelationshipPermissions(Relationship relationship)
-    {
-        // Apply the relationship permissions to casbin enforcer
-        // domain: the user
-        // status is friends: all permissions are allowed by default, expect specially specified
-        // status is blocked: all permissions are disallowed by default, expect specially specified
-        // others: use the default permissions by design
-
-        var domain = $"user:{relationship.AccountId.ToString()}";
-        var target = $"user:{relationship.RelatedId.ToString()}";
-
-        await pm.RemovePermissionNode(target, domain, "*");
-
-        bool? value = relationship.Status switch
-        {
-            RelationshipStatus.Friends => true,
-            RelationshipStatus.Blocked => false,
-            _ => null,
-        };
-        if (value is null) return;
-
-        await pm.AddPermissionNode(target, domain, "*", value);
-    }
 }
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Account/RelationshipController.cs b/DysonNetwork.Sphere/Account/RelationshipController.cs
index 204bd8e..bfc1603 100644
--- a/DysonNetwork.Sphere/Account/RelationshipController.cs
+++ b/DysonNetwork.Sphere/Account/RelationshipController.cs
@@ -7,7 +7,7 @@ namespace DysonNetwork.Sphere.Account;
 
 [ApiController]
 [Route("/relationships")]
-public class RelationshipController(AppDatabase db, AccountService accounts) : ControllerBase
+public class RelationshipController(AppDatabase db, RelationshipService rels) : ControllerBase
 {
     [HttpGet]
     [Authorize]
@@ -48,7 +48,7 @@ public class RelationshipController(AppDatabase db, AccountService accounts) : C
 
         try
         {
-            var relationship = await accounts.CreateRelationship(
+            var relationship = await rels.CreateRelationship(
                 currentUser, relatedUser, request.Status
             );
             return relationship;
diff --git a/DysonNetwork.Sphere/Account/RelationshipService.cs b/DysonNetwork.Sphere/Account/RelationshipService.cs
new file mode 100644
index 0000000..4ed4dc6
--- /dev/null
+++ b/DysonNetwork.Sphere/Account/RelationshipService.cs
@@ -0,0 +1,171 @@
+using DysonNetwork.Sphere.Permission;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Caching.Memory;
+using NodaTime;
+
+namespace DysonNetwork.Sphere.Account;
+
+public class RelationshipService(AppDatabase db, PermissionService pm, IMemoryCache cache)
+{
+    public async Task<bool> HasExistingRelationship(Account userA, Account userB)
+    {
+        var count = await db.AccountRelationships
+            .Where(r => (r.AccountId == userA.Id && r.AccountId == userB.Id) ||
+                        (r.AccountId == userB.Id && r.AccountId == userA.Id))
+            .CountAsync();
+        return count > 0;
+    }
+
+    public async Task<Relationship?> GetRelationship(
+        Account account,
+        Account related,
+        RelationshipStatus? status,
+        bool ignoreExpired = false
+    )
+    {
+        var now = Instant.FromDateTimeUtc(DateTime.UtcNow);
+        var queries = db.AccountRelationships
+            .Where(r => r.AccountId == account.Id && r.AccountId == related.Id);
+        if (ignoreExpired) queries = queries.Where(r => r.ExpiredAt > now);
+        if (status is not null) queries = queries.Where(r => r.Status == status);
+        var relationship = await queries.FirstOrDefaultAsync();
+        return relationship;
+    }
+
+    public async Task<Relationship> CreateRelationship(Account sender, Account target, RelationshipStatus status)
+    {
+        if (status == RelationshipStatus.Pending)
+            throw new InvalidOperationException(
+                "Cannot create relationship with pending status, use SendFriendRequest instead.");
+        if (await HasExistingRelationship(sender, target))
+            throw new InvalidOperationException("Found existing relationship between you and target user.");
+
+        var relationship = new Relationship
+        {
+            Account = sender,
+            AccountId = sender.Id,
+            Related = target,
+            RelatedId = target.Id,
+            Status = status
+        };
+
+        db.AccountRelationships.Add(relationship);
+        await db.SaveChangesAsync();
+        await ApplyRelationshipPermissions(relationship);
+        
+        cache.Remove($"dyn_user_friends_{relationship.AccountId}");
+        cache.Remove($"dyn_user_friends_{relationship.RelatedId}");
+
+        return relationship;
+    }
+
+    public async Task<Relationship> SendFriendRequest(Account sender, Account target)
+    {
+        if (await HasExistingRelationship(sender, target))
+            throw new InvalidOperationException("Found existing relationship between you and target user.");
+
+        var relationship = new Relationship
+        {
+            Account = sender,
+            AccountId = sender.Id,
+            Related = target,
+            RelatedId = target.Id,
+            Status = RelationshipStatus.Pending,
+            ExpiredAt = Instant.FromDateTimeUtc(DateTime.UtcNow.AddDays(7))
+        };
+
+        db.AccountRelationships.Add(relationship);
+        await db.SaveChangesAsync();
+
+        return relationship;
+    }
+
+    public async Task<Relationship> AcceptFriendRelationship(
+        Relationship relationship,
+        RelationshipStatus status = RelationshipStatus.Friends
+    )
+    {
+        if (relationship.Status == RelationshipStatus.Pending)
+            throw new ArgumentException("Cannot accept friend request by setting the new status to pending.");
+
+        // Whatever the receiver decides to apply which status to the relationship,
+        // the sender should always see the user as a friend since the sender ask for it
+        relationship.Status = RelationshipStatus.Friends;
+        relationship.ExpiredAt = null;
+        db.Update(relationship);
+
+        var relationshipBackward = new Relationship
+        {
+            Account = relationship.Related,
+            AccountId = relationship.RelatedId,
+            Related = relationship.Account,
+            RelatedId = relationship.AccountId,
+            Status = status
+        };
+        db.AccountRelationships.Add(relationshipBackward);
+
+        await db.SaveChangesAsync();
+
+        await Task.WhenAll(
+            ApplyRelationshipPermissions(relationship),
+            ApplyRelationshipPermissions(relationshipBackward)
+        );
+        
+        cache.Remove($"dyn_user_friends_{relationship.AccountId}");
+        cache.Remove($"dyn_user_friends_{relationship.RelatedId}");
+
+        return relationshipBackward;
+    }
+
+    public async Task<Relationship> UpdateRelationship(Account account, Account related, RelationshipStatus status)
+    {
+        var relationship = await GetRelationship(account, related, status);
+        if (relationship is null) throw new ArgumentException("There is no relationship between you and the user.");
+        if (relationship.Status == status) return relationship;
+        relationship.Status = status;
+        db.Update(relationship);
+        await db.SaveChangesAsync();
+        await ApplyRelationshipPermissions(relationship);
+        cache.Remove($"dyn_user_friends_{related.Id}");
+        return relationship;
+    }
+
+    public async Task<List<long>> ListAccountFriends(Account account)
+    {
+        if (!cache.TryGetValue($"dyn_user_friends_{account.Id}", out List<long>? friends))
+        {
+            friends = await db.AccountRelationships
+                .Where(r => r.RelatedId == account.Id)
+                .Where(r => r.Status == RelationshipStatus.Friends)
+                .Select(r => r.AccountId)
+                .ToListAsync();
+            cache.Set($"dyn_user_friends_{account.Id}", friends, TimeSpan.FromHours(1));
+        }
+
+        return friends ?? [];
+    }
+
+    private async Task ApplyRelationshipPermissions(Relationship relationship)
+    {
+        // Apply the relationship permissions to casbin enforcer
+        // domain: the user
+        // status is friends: all permissions are allowed by default, expect specially specified
+        // status is blocked: all permissions are disallowed by default, expect specially specified
+        // others: use the default permissions by design
+
+        var domain = $"user:{relationship.AccountId.ToString()}";
+        var target = $"user:{relationship.RelatedId.ToString()}";
+
+        await pm.RemovePermissionNode(target, domain, "*");
+
+        bool? value = relationship.Status switch
+        {
+            RelationshipStatus.Friends => true,
+            RelationshipStatus.Blocked => false,
+            _ => null,
+        };
+        if (value is null) return;
+
+        await pm.AddPermissionNode(target, domain, "*", value);
+    }
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Activity/Activity.cs b/DysonNetwork.Sphere/Activity/Activity.cs
new file mode 100644
index 0000000..4e90e80
--- /dev/null
+++ b/DysonNetwork.Sphere/Activity/Activity.cs
@@ -0,0 +1,21 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace DysonNetwork.Sphere.Activity;
+
+public enum ActivityVisibility
+{
+    Public,
+    Friends,
+}
+
+public class Activity : ModelBase
+{
+    public Guid Id { get; set; } = Guid.NewGuid();
+    [MaxLength(1024)] public string Type { get; set; } = null!;
+    [MaxLength(4096)] public string ResourceIdentifier { get; set; } = null!;
+    public ActivityVisibility Visibility { get; set; } = ActivityVisibility.Public;
+    public Dictionary<string, object> Meta =  new();
+    
+    public long AccountId { get; set; }
+    public Account.Account Account { get; set; } = null!;
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Activity/ActivityController.cs b/DysonNetwork.Sphere/Activity/ActivityController.cs
new file mode 100644
index 0000000..b772ac0
--- /dev/null
+++ b/DysonNetwork.Sphere/Activity/ActivityController.cs
@@ -0,0 +1,33 @@
+using DysonNetwork.Sphere.Account;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.EntityFrameworkCore;
+
+namespace DysonNetwork.Sphere.Activity;
+
+[ApiController]
+[Route("/activities")]
+public class ActivityController(AppDatabase db, ActivityService act, RelationshipService rels) : ControllerBase
+{
+    [HttpGet]
+    public async Task<ActionResult<List<Activity>>> ListActivities([FromQuery] int offset, [FromQuery] int take = 20)
+    {
+        HttpContext.Items.TryGetValue("CurrentUser", out var currentUserValue);
+        var currentUser = currentUserValue as Account.Account;
+        var userFriends = await rels.ListAccountFriends(currentUser!);
+
+        var totalCount = await db.Activities
+            .FilterWithVisibility(currentUser, userFriends)
+            .CountAsync();
+        var posts = await db.Activities
+            .Include(e => e.Account)
+            .FilterWithVisibility(currentUser, userFriends)
+            .OrderByDescending(e => e.CreatedAt)
+            .Skip(offset)
+            .Take(take)
+            .ToListAsync();
+
+        Response.Headers["X-Total"] = totalCount.ToString();
+
+        return Ok(posts); 
+    }
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Activity/ActivityService.cs b/DysonNetwork.Sphere/Activity/ActivityService.cs
new file mode 100644
index 0000000..4258ca1
--- /dev/null
+++ b/DysonNetwork.Sphere/Activity/ActivityService.cs
@@ -0,0 +1,54 @@
+using DysonNetwork.Sphere.Post;
+using NodaTime;
+
+namespace DysonNetwork.Sphere.Activity;
+
+public class ActivityService(AppDatabase db)
+{
+    public async Task<Activity> CreateActivity(
+        Account.Account user,
+        string type,
+        string identifier,
+        ActivityVisibility visibility = ActivityVisibility.Public
+    )
+    {
+        var activity = new Activity
+        {
+            Type = type,
+            ResourceIdentifier = identifier,
+            Visibility = visibility,
+            AccountId = user.Id,
+        };
+
+        db.Activities.Add(activity);
+        await db.SaveChangesAsync();
+
+        return activity;
+    }
+
+    public async Task CreateNewPostActivity(Account.Account user, Post.Post post)
+    {
+        if (post.Visibility is PostVisibility.Unlisted or PostVisibility.Private) return;
+
+        var identifier = $"posts/{post.Id}";
+        await CreateActivity(user, "posts.new", identifier,
+            post.Visibility == PostVisibility.Friends ? ActivityVisibility.Friends : ActivityVisibility.Public);
+    }
+}
+
+public static class ActivityQueryExtensions
+{
+    public static IQueryable<Activity> FilterWithVisibility(this IQueryable<Activity> source,
+        Account.Account? currentUser, List<long> userFriends)
+    {
+        var now = Instant.FromDateTimeUtc(DateTime.UtcNow);
+
+        if (currentUser is null)
+            return source.Where(e => e.Visibility == ActivityVisibility.Public);
+
+        return source
+            .Where(e => e.Visibility != ActivityVisibility.Friends ||
+                        userFriends.Contains(e.AccountId) ||
+                        e.AccountId == currentUser.Id);
+    }
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/AppDatabase.cs b/DysonNetwork.Sphere/AppDatabase.cs
index ebcf170..6ece080 100644
--- a/DysonNetwork.Sphere/AppDatabase.cs
+++ b/DysonNetwork.Sphere/AppDatabase.cs
@@ -37,6 +37,8 @@ public class AppDatabase(
     public DbSet<Auth.Challenge> AuthChallenges { get; set; }
 
     public DbSet<Storage.CloudFile> Files { get; set; }
+    
+    public DbSet<Activity.Activity> Activities { get; set; }
 
     public DbSet<Post.Publisher> Publishers { get; set; }
     public DbSet<Post.PublisherMember> PublisherMembers { get; set; }
diff --git a/DysonNetwork.Sphere/Connection/WebSocketController.cs b/DysonNetwork.Sphere/Connection/WebSocketController.cs
index 7172627..6db5ac6 100644
--- a/DysonNetwork.Sphere/Connection/WebSocketController.cs
+++ b/DysonNetwork.Sphere/Connection/WebSocketController.cs
@@ -8,13 +8,8 @@ namespace DysonNetwork.Sphere.Connection;
 
 [ApiController]
 [Route("/ws")]
-public class WebSocketController(ILogger<WebSocketContext> logger) : ControllerBase
+public class WebSocketController(WebSocketService ws, ILogger<WebSocketContext> logger) : ControllerBase
 {
-    private static readonly ConcurrentDictionary<
-        (long AccountId, string DeviceId),
-        (WebSocket Socket, CancellationTokenSource Cts)
-    > ActiveConnections = new();
-
     [Route("/ws")]
     [Authorize]
     [SwaggerIgnore]
@@ -42,7 +37,7 @@ public class WebSocketController(ILogger<WebSocketContext> logger) : ControllerB
         var cts = new CancellationTokenSource();
         var connectionKey = (accountId, deviceId);
 
-        if (!ActiveConnections.TryAdd(connectionKey, (webSocket, cts)))
+        if (!ws.TryAdd(connectionKey, webSocket, cts))
         {
             await webSocket.CloseAsync(
                 WebSocketCloseStatus.InternalServerError,
@@ -57,7 +52,7 @@ public class WebSocketController(ILogger<WebSocketContext> logger) : ControllerB
 
         try
         {
-            await _ConnectionEventLoop(webSocket, connectionKey, cts.Token);
+            await _ConnectionEventLoop(connectionKey, webSocket, cts.Token);
         }
         catch (Exception ex)
         {
@@ -65,16 +60,15 @@ public class WebSocketController(ILogger<WebSocketContext> logger) : ControllerB
         }
         finally
         {
-            ActiveConnections.TryRemove(connectionKey, out _);
-            cts.Dispose();
+            ws.Disconnect(connectionKey);
             logger.LogInformation(
                 $"Connection disconnected with user @{currentUser.Name}#{currentUser.Id} and device #{deviceId}");
         }
     }
 
-    private static async Task _ConnectionEventLoop(
-        WebSocket webSocket,
+    private async Task _ConnectionEventLoop(
         (long AccountId, string DeviceId) connectionKey,
+        WebSocket webSocket,
         CancellationToken cancellationToken
     )
     {
@@ -93,41 +87,17 @@ public class WebSocketController(ILogger<WebSocketContext> logger) : ControllerB
                 );
             }
 
-            await webSocket.CloseAsync(
-                receiveResult.CloseStatus.Value,
-                receiveResult.CloseStatusDescription,
-                cancellationToken
-            );
+            // TODO handle values
         }
         catch (OperationCanceledException)
         {
-            // Connection was canceled, close it gracefully
             if (
                 webSocket.State != WebSocketState.Closed
                 && webSocket.State != WebSocketState.Aborted
             )
             {
-                await webSocket.CloseAsync(
-                    WebSocketCloseStatus.NormalClosure,
-                    "Connection closed by server",
-                    CancellationToken.None
-                );
+                ws.Disconnect(connectionKey);
             }
         }
     }
-
-    // This method will be used later to send messages to specific connections
-    public static async Task SendMessageAsync(long accountId, string deviceId, string message)
-    {
-        if (ActiveConnections.TryGetValue((accountId, deviceId), out var connection))
-        {
-            var buffer = System.Text.Encoding.UTF8.GetBytes(message);
-            await connection.Socket.SendAsync(
-                new ArraySegment<byte>(buffer, 0, buffer.Length),
-                WebSocketMessageType.Text,
-                true,
-                connection.Cts.Token
-            );
-        }
-    }
 }
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Connection/WebSocketService.cs b/DysonNetwork.Sphere/Connection/WebSocketService.cs
new file mode 100644
index 0000000..61e548d
--- /dev/null
+++ b/DysonNetwork.Sphere/Connection/WebSocketService.cs
@@ -0,0 +1,35 @@
+using System.Collections.Concurrent;
+using System.Net.WebSockets;
+
+namespace DysonNetwork.Sphere.Connection;
+
+public class WebSocketService
+{
+    public static readonly ConcurrentDictionary<
+        (long AccountId, string DeviceId),
+        (WebSocket Socket, CancellationTokenSource Cts)
+    > ActiveConnections = new();
+
+    public bool TryAdd(
+        (long AccountId, string DeviceId) key,
+        WebSocket socket,
+        CancellationTokenSource cts
+    )
+    {
+        if (ActiveConnections.TryGetValue(key, out _))
+            Disconnect(key, "Just connected somewhere else with the same identifier."); // Disconnect the previous one using the same identifier
+        return ActiveConnections.TryAdd(key, (socket, cts));
+    }
+
+    public void Disconnect((long AccountId, string DeviceId) key, string? reason = null)
+    {
+        if (!ActiveConnections.TryGetValue(key, out var data)) return;
+        data.Socket.CloseAsync(
+            WebSocketCloseStatus.NormalClosure,
+            reason ?? "Server just decided to disconnect.",
+            CancellationToken.None
+        );
+        data.Cts.Cancel();
+        ActiveConnections.TryRemove(key, out _);
+    }
+}
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Post/PostController.cs b/DysonNetwork.Sphere/Post/PostController.cs
index 31e95e8..2b33737 100644
--- a/DysonNetwork.Sphere/Post/PostController.cs
+++ b/DysonNetwork.Sphere/Post/PostController.cs
@@ -1,5 +1,6 @@
 using System.ComponentModel.DataAnnotations;
 using Casbin;
+using DysonNetwork.Sphere.Account;
 using DysonNetwork.Sphere.Permission;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
@@ -9,16 +10,17 @@ namespace DysonNetwork.Sphere.Post;
 
 [ApiController]
 [Route("/posts")]
-public class PostController(AppDatabase db, PostService ps) : ControllerBase
+public class PostController(AppDatabase db, PostService ps, RelationshipService rels) : ControllerBase
 {
     [HttpGet]
     public async Task<ActionResult<List<Post>>> ListPosts([FromQuery] int offset = 0, [FromQuery] int take = 20)
     {
         HttpContext.Items.TryGetValue("CurrentUser", out var currentUserValue);
         var currentUser = currentUserValue as Account.Account;
+        var userFriends = await rels.ListAccountFriends(currentUser!);
 
         var totalCount = await db.Posts
-            .FilterWithVisibility(currentUser, isListing: true)
+            .FilterWithVisibility(currentUser, userFriends, isListing: true)
             .CountAsync();
         var posts = await db.Posts
             .Include(e => e.Publisher)
@@ -30,7 +32,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
             .Include(e => e.Categories)
             .Include(e => e.Tags)
             .Where(e => e.RepliedPostId == null)
-            .FilterWithVisibility(currentUser, isListing: true)
+            .FilterWithVisibility(currentUser, userFriends, isListing: true)
             .OrderByDescending(e => e.PublishedAt ?? e.CreatedAt)
             .Skip(offset)
             .Take(take)
@@ -46,6 +48,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
     {
         HttpContext.Items.TryGetValue("CurrentUser", out var currentUserValue);
         var currentUser = currentUserValue as Account.Account;
+        var userFriends = await rels.ListAccountFriends(currentUser!);
 
         var post = await db.Posts
             .Where(e => e.Id == id)
@@ -58,7 +61,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
             .Include(e => e.Tags)
             .Include(e => e.Categories)
             .Include(e => e.Attachments)
-            .FilterWithVisibility(currentUser)
+            .FilterWithVisibility(currentUser, userFriends)
             .FirstOrDefaultAsync();
         if (post is null) return NotFound();
 
@@ -71,6 +74,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
     {
         HttpContext.Items.TryGetValue("CurrentUser", out var currentUserValue);
         var currentUser = currentUserValue as Account.Account;
+        var userFriends = await rels.ListAccountFriends(currentUser!);
 
         var post = await db.Posts
             .Where(e => e.Id == id)
@@ -79,7 +83,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
 
         var totalCount = await db.Posts
             .Where(e => e.RepliedPostId == post.Id)
-            .FilterWithVisibility(currentUser, isListing: true)
+            .FilterWithVisibility(currentUser, userFriends, isListing: true)
             .CountAsync();
         var posts = await db.Posts
             .Where(e => e.RepliedPostId == id)
@@ -91,7 +95,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
             .Include(e => e.Attachments)
             .Include(e => e.Categories)
             .Include(e => e.Tags)
-            .FilterWithVisibility(currentUser, isListing: true)
+            .FilterWithVisibility(currentUser, userFriends, isListing: true)
             .OrderByDescending(e => e.PublishedAt ?? e.CreatedAt)
             .Skip(offset)
             .Take(take)
@@ -179,6 +183,7 @@ public class PostController(AppDatabase db, PostService ps) : ControllerBase
         try
         {
             post = await ps.PostAsync(
+                currentUser,
                 post,
                 attachments: request.Attachments,
                 tags: request.Tags,
diff --git a/DysonNetwork.Sphere/Post/PostService.cs b/DysonNetwork.Sphere/Post/PostService.cs
index 58a12e1..35ebc1b 100644
--- a/DysonNetwork.Sphere/Post/PostService.cs
+++ b/DysonNetwork.Sphere/Post/PostService.cs
@@ -1,12 +1,14 @@
+using DysonNetwork.Sphere.Activity;
 using DysonNetwork.Sphere.Storage;
 using Microsoft.EntityFrameworkCore;
 using NodaTime;
 
 namespace DysonNetwork.Sphere.Post;
 
-public class PostService(AppDatabase db, FileService fs)
+public class PostService(AppDatabase db, FileService fs, ActivityService act)
 {
     public async Task<Post> PostAsync(
+        Account.Account user,
         Post post,
         List<string>? attachments = null,
         List<string>? tags = null,
@@ -66,6 +68,8 @@ public class PostService(AppDatabase db, FileService fs)
         await db.SaveChangesAsync();
         await fs.MarkUsageRangeAsync(post.Attachments, 1);
 
+        await act.CreateNewPostActivity(user, post);
+
         return post;
     }
 
@@ -153,7 +157,7 @@ public class PostService(AppDatabase db, FileService fs)
 public static class PostQueryExtensions
 {
     public static IQueryable<Post> FilterWithVisibility(this IQueryable<Post> source, Account.Account? currentUser,
-        bool isListing = false)
+        List<long> userFriends, bool isListing = false)
     {
         var now = Instant.FromDateTimeUtc(DateTime.UtcNow);
 
@@ -172,6 +176,9 @@ public static class PostQueryExtensions
 
         return source
             .Where(e => e.PublishedAt != null && now >= e.PublishedAt && e.Publisher.AccountId == currentUser.Id)
-            .Where(e => e.Visibility != PostVisibility.Private || e.Publisher.AccountId == currentUser.Id);
+            .Where(e => e.Visibility != PostVisibility.Private || e.Publisher.AccountId == currentUser.Id)
+            .Where(e => e.Visibility != PostVisibility.Friends ||
+                        (e.Publisher.AccountId != null && userFriends.Contains(e.Publisher.AccountId.Value)) ||
+                        e.Publisher.AccountId == currentUser.Id);
     }
 }
\ No newline at end of file
diff --git a/DysonNetwork.Sphere/Program.cs b/DysonNetwork.Sphere/Program.cs
index 540421f..a1de52c 100644
--- a/DysonNetwork.Sphere/Program.cs
+++ b/DysonNetwork.Sphere/Program.cs
@@ -7,7 +7,9 @@ using Casbin;
 using Casbin.Persist.Adapter.EFCore;
 using DysonNetwork.Sphere;
 using DysonNetwork.Sphere.Account;
+using DysonNetwork.Sphere.Activity;
 using DysonNetwork.Sphere.Auth;
+using DysonNetwork.Sphere.Connection;
 using DysonNetwork.Sphere.Permission;
 using DysonNetwork.Sphere.Post;
 using DysonNetwork.Sphere.Storage;
@@ -114,14 +116,17 @@ builder.Services.AddSwaggerGen(options =>
 });
 builder.Services.AddOpenApi();
 
+builder.Services.AddScoped<WebSocketService>();
 builder.Services.AddScoped<EmailService>();
 builder.Services.AddScoped<PermissionService>();
 builder.Services.AddScoped<AccountService>();
+builder.Services.AddScoped<RelationshipService>();
 builder.Services.AddScoped<MagicSpellService>();
 builder.Services.AddScoped<NotificationService>();
 builder.Services.AddScoped<AuthService>();
 builder.Services.AddScoped<FileService>();
 builder.Services.AddScoped<PublisherService>();
+builder.Services.AddScoped<ActivityService>();
 builder.Services.AddScoped<PostService>();
 
 // Timed task