From bbb8595107efce1653fde5d9468df077d529b6ca Mon Sep 17 00:00:00 2001
From: Joffrey JAFFEUX <j.jaffeux@gmail.com>
Date: Mon, 18 Mar 2024 08:35:07 +0100
Subject: [PATCH] PERF: defer loading channels (#26155)

Prior to this change we would pre-load all the user channels which making initial page load slower. This change will make them be loaded right after initial load. In the past this was not possible as the channels would have to be loaded on each page transition. However since about a year, we made the channels to be cached on the frontend and no other request will be needed.

I have decided for now to not show a loading state in the sidebar as I think it would be noise, but we can reconsider this later.

Note given we don't have the channels loaded at first certain things where harder to accomplish. The biggest UX change of this commit is that we removed all the complex logic of computing the best channel to display when you load /chat. We will now store the id of the last channel you visited and will use this id to decide which channel to show.
---
 .../api/current_user_channels_controller.rb   |  13 +-
 .../services/chat/list_channel_messages.rb    |   8 +
 .../app/services/chat/list_user_channels.rb   |  43 +++
 .../components/channels-list-public.gjs       |  18 +-
 .../discourse/components/chat-footer.gjs      |  11 +-
 .../discourse/initializers/chat-setup.js      |   8 +-
 .../discourse/initializers/chat-sidebar.js    | 115 +++---
 .../discourse/routes/chat-index.js            |  15 +-
 .../services/chat-channels-manager.js         |   8 +
 .../discourse/services/chat-state-manager.js  |   1 +
 .../javascripts/discourse/services/chat.js    |  88 ++---
 plugins/chat/lib/chat/engine.rb               |   1 +
 plugins/chat/plugin.rb                        |  26 +-
 plugins/chat/spec/plugin_spec.rb              |  69 ----
 .../chat/api/current_user_channels_spec.rb    |  87 -----
 .../core_ext/latest_performance_spec.rb       |  58 ---
 .../chat/list_channel_messages_spec.rb        |   8 +
 .../services/chat/list_user_channels_spec.rb  |  76 ++++
 plugins/chat/spec/system/chat_channel_spec.rb |  34 +-
 .../chat/spec/system/chat_new_message_spec.rb |   3 +-
 plugins/chat/spec/system/drawer_spec.rb       |   2 +
 .../chat/spec/system/mention_warnings_spec.rb |  29 +-
 plugins/chat/spec/system/navigation_spec.rb   |  11 +-
 .../chat/spec/system/removing_channel_spec.rb |   5 +-
 .../acceptance/hashtag-css-generator-test.js  |  86 ++---
 .../javascripts/acceptance/mentions-test.js   | 107 ------
 .../user-status-on-mentions-test.js           | 332 ------------------
 .../components/chat-channel-test.js           |   6 +
 28 files changed, 391 insertions(+), 877 deletions(-)
 create mode 100644 plugins/chat/app/services/chat/list_user_channels.rb
 delete mode 100644 plugins/chat/spec/requests/core_ext/latest_performance_spec.rb
 create mode 100644 plugins/chat/spec/services/chat/list_user_channels_spec.rb
 delete mode 100644 plugins/chat/test/javascripts/acceptance/mentions-test.js
 delete mode 100644 plugins/chat/test/javascripts/acceptance/user-status-on-mentions-test.js

diff --git a/plugins/chat/app/controllers/chat/api/current_user_channels_controller.rb b/plugins/chat/app/controllers/chat/api/current_user_channels_controller.rb
index 613af229090..02660ef5cc5 100644
--- a/plugins/chat/app/controllers/chat/api/current_user_channels_controller.rb
+++ b/plugins/chat/app/controllers/chat/api/current_user_channels_controller.rb
@@ -2,7 +2,16 @@
 
 class Chat::Api::CurrentUserChannelsController < Chat::ApiController
   def index
-    structured = Chat::ChannelFetcher.structured(guardian)
-    render_serialized(structured, Chat::ChannelIndexSerializer, root: false)
+    with_service(Chat::ListUserChannels) do
+      on_success do
+        render_serialized(
+          result.structured,
+          Chat::ChannelIndexSerializer,
+          root: false,
+          post_allowed_category_ids: result.post_allowed_category_ids,
+        )
+      end
+      on_failure { render(json: failed_json, status: 422) }
+    end
   end
 end
diff --git a/plugins/chat/app/services/chat/list_channel_messages.rb b/plugins/chat/app/services/chat/list_channel_messages.rb
index 0c9ed6a1594..36daf51e67c 100644
--- a/plugins/chat/app/services/chat/list_channel_messages.rb
+++ b/plugins/chat/app/services/chat/list_channel_messages.rb
@@ -29,6 +29,7 @@ module Chat
     step :fetch_thread_participants
     step :fetch_thread_memberships
     step :update_membership_last_viewed_at
+    step :update_user_last_channel
 
     class Contract
       attribute :channel_id, :integer
@@ -170,5 +171,12 @@ module Chat
         context.membership&.update!(last_viewed_at: Time.zone.now)
       end
     end
+
+    def update_user_last_channel(guardian:, channel:)
+      Scheduler::Defer.later "Chat::ListChannelMessages - defer update_user_last_channel" do
+        return if guardian.user.custom_fields[::Chat::LAST_CHAT_CHANNEL_ID] == channel.id
+        guardian.user.upsert_custom_fields(::Chat::LAST_CHAT_CHANNEL_ID => channel.id)
+      end
+    end
   end
 end
diff --git a/plugins/chat/app/services/chat/list_user_channels.rb b/plugins/chat/app/services/chat/list_user_channels.rb
new file mode 100644
index 00000000000..65a4eae7996
--- /dev/null
+++ b/plugins/chat/app/services/chat/list_user_channels.rb
@@ -0,0 +1,43 @@
+# frozen_string_literal: true
+
+module Chat
+  # List of the channels a user is tracking
+  #
+  # @example
+  #  Chat::ListUserChannels.call(guardian: guardian, **optional_params)
+  #
+  class ListUserChannels
+    include Service::Base
+
+    # @!method call(guardian:)
+    #   @param [Guardian] guardian
+    #   @return [Service::Base::Context]
+
+    model :structured
+    step :inject_unread_thread_overview
+    model :post_allowed_category_ids, optional: true
+
+    private
+
+    def fetch_structured(guardian:)
+      ::Chat::ChannelFetcher.structured(guardian)
+    end
+
+    def inject_unread_thread_overview(structured:, guardian:)
+      structured[:unread_thread_overview] = ::Chat::TrackingStateReportQuery.call(
+        guardian: guardian,
+        channel_ids: structured[:public_channels].map(&:id),
+        include_threads: true,
+        include_read: false,
+        include_last_reply_details: true,
+      ).thread_unread_overview_by_channel
+    end
+
+    def fetch_post_allowed_category_ids(guardian:, structured:)
+      ::Category
+        .post_create_allowed(guardian)
+        .where(id: structured[:public_channels].map { |c| c.chatable_id })
+        .pluck(:id)
+    end
+  end
+end
diff --git a/plugins/chat/assets/javascripts/discourse/components/channels-list-public.gjs b/plugins/chat/assets/javascripts/discourse/components/channels-list-public.gjs
index f89c2541848..842804615d3 100644
--- a/plugins/chat/assets/javascripts/discourse/components/channels-list-public.gjs
+++ b/plugins/chat/assets/javascripts/discourse/components/channels-list-public.gjs
@@ -13,6 +13,7 @@ import ChatChannelRow from "./chat-channel-row";
 
 export default class ChannelsListPublic extends Component {
   @service chatChannelsManager;
+  @service chatStateManager;
   @service chatTrackingStateManager;
   @service site;
   @service siteSettings;
@@ -23,7 +24,10 @@ export default class ChannelsListPublic extends Component {
   }
 
   get publicMessageChannelsEmpty() {
-    return this.chatChannelsManager.publicMessageChannels?.length === 0;
+    return (
+      this.chatChannelsManager.publicMessageChannels?.length === 0 &&
+      this.chatStateManager.hasPreloadedChannels
+    );
   }
 
   get displayPublicChannels() {
@@ -31,6 +35,10 @@ export default class ChannelsListPublic extends Component {
       return false;
     }
 
+    if (!this.chatStateManager.hasPreloadedChannels) {
+      return false;
+    }
+
     if (this.publicMessageChannelsEmpty) {
       return (
         this.currentUser?.staff ||
@@ -45,10 +53,8 @@ export default class ChannelsListPublic extends Component {
     return this.chatTrackingStateManager.hasUnreadThreads;
   }
 
-  get isThreadEnabledInAnyChannel() {
-    return this.currentUser?.chat_channels?.public_channels?.some(
-      (channel) => channel.threading_enabled
-    );
+  get hasThreadedChannels() {
+    return this.chatChannelsManager.hasThreadedChannels;
   }
 
   @action
@@ -57,7 +63,7 @@ export default class ChannelsListPublic extends Component {
   }
 
   <template>
-    {{#if (and this.site.desktopView this.isThreadEnabledInAnyChannel)}}
+    {{#if (and this.site.desktopView this.hasThreadedChannels)}}
       <LinkTo @route="chat.threads" class="chat-channel-row --threads">
         <span class="chat-channel-title">
           {{dIcon "discourse-threads" class="chat-user-threads__icon"}}
diff --git a/plugins/chat/assets/javascripts/discourse/components/chat-footer.gjs b/plugins/chat/assets/javascripts/discourse/components/chat-footer.gjs
index 94f0eb91903..e74f523f98e 100644
--- a/plugins/chat/assets/javascripts/discourse/components/chat-footer.gjs
+++ b/plugins/chat/assets/javascripts/discourse/components/chat-footer.gjs
@@ -15,14 +15,14 @@ export default class ChatFooter extends Component {
   @service chat;
   @service siteSettings;
   @service currentUser;
+  @service chatChannelsManager;
+  @service chatStateManager;
 
   get includeThreads() {
     if (!this.siteSettings.chat_threads_enabled) {
       return false;
     }
-    return this.currentUser?.chat_channels?.public_channels?.some(
-      (channel) => channel.threading_enabled
-    );
+    return this.chatChannelsManager.hasThreadedChannels;
   }
 
   get directMessagesEnabled() {
@@ -30,7 +30,10 @@ export default class ChatFooter extends Component {
   }
 
   get shouldRenderFooter() {
-    return this.includeThreads || this.directMessagesEnabled;
+    return (
+      this.chatStateManager.hasPreloadedChannels &&
+      (this.includeThreads || this.directMessagesEnabled)
+    );
   }
 
   <template>
diff --git a/plugins/chat/assets/javascripts/discourse/initializers/chat-setup.js b/plugins/chat/assets/javascripts/discourse/initializers/chat-setup.js
index b316fa9ae9a..cb238774cf2 100644
--- a/plugins/chat/assets/javascripts/discourse/initializers/chat-setup.js
+++ b/plugins/chat/assets/javascripts/discourse/initializers/chat-setup.js
@@ -148,13 +148,7 @@ export default {
 
       document.body.classList.add("chat-enabled");
 
-      const currentUser = api.getCurrentUser();
-
-      // NOTE: chat_channels is more than a simple array, it also contains
-      // tracking and membership data, see Chat::StructuredChannelSerializer
-      if (currentUser?.chat_channels) {
-        this.chatService.setupWithPreloadedChannels(currentUser.chat_channels);
-      }
+      this.chatService.loadChannels();
 
       const chatNotificationManager = container.lookup(
         "service:chat-notification-manager"
diff --git a/plugins/chat/assets/javascripts/discourse/initializers/chat-sidebar.js b/plugins/chat/assets/javascripts/discourse/initializers/chat-sidebar.js
index 6472d9a91ae..329573dc143 100644
--- a/plugins/chat/assets/javascripts/discourse/initializers/chat-sidebar.js
+++ b/plugins/chat/assets/javascripts/discourse/initializers/chat-sidebar.js
@@ -48,69 +48,68 @@ export default {
     });
 
     withPluginApi("1.3.0", (api) => {
-      const isThreadEnabledInAnyChannel =
-        this.currentUser?.chat_channels?.public_channels?.some(
-          (channel) => channel.threading_enabled === true
-        );
+      const chatChannelsManager = container.lookup(
+        "service:chat-channels-manager"
+      );
 
-      if (isThreadEnabledInAnyChannel) {
-        api.addSidebarSection(
-          (BaseCustomSidebarSection, BaseCustomSidebarSectionLink) => {
-            const SidebarChatMyThreadsSectionLink = class extends BaseCustomSidebarSectionLink {
-              route = "chat.threads";
-              text = I18n.t("chat.my_threads.title");
-              title = I18n.t("chat.my_threads.title");
-              name = "user-threads";
-              prefixType = "icon";
-              prefixValue = "discourse-threads";
-              suffixType = "icon";
-              suffixCSSClass = "unread";
+      api.addSidebarSection(
+        (BaseCustomSidebarSection, BaseCustomSidebarSectionLink) => {
+          const SidebarChatMyThreadsSectionLink = class extends BaseCustomSidebarSectionLink {
+            route = "chat.threads";
+            text = I18n.t("chat.my_threads.title");
+            title = I18n.t("chat.my_threads.title");
+            name = "user-threads";
+            prefixType = "icon";
+            prefixValue = "discourse-threads";
+            suffixType = "icon";
+            suffixCSSClass = "unread";
 
-              constructor() {
-                super(...arguments);
+            constructor() {
+              super(...arguments);
 
-                if (container.isDestroyed) {
-                  return;
-                }
-
-                this.chatChannelsManager = container.lookup(
-                  "service:chat-channels-manager"
-                );
+              if (container.isDestroyed) {
+                return;
               }
+            }
 
-              get suffixValue() {
-                return this.chatChannelsManager.publicMessageChannels.some(
-                  (channel) => channel.unreadThreadsCount > 0
-                )
-                  ? "circle"
-                  : "";
-              }
-            };
+            get suffixValue() {
+              return chatChannelsManager.publicMessageChannels.some(
+                (channel) => channel.unreadThreadsCount > 0
+              )
+                ? "circle"
+                : "";
+            }
+          };
 
-            const SidebarChatMyThreadsSection = class extends BaseCustomSidebarSection {
-              // we only show `My Threads` link
-              hideSectionHeader = true;
+          const SidebarChatMyThreadsSection = class extends BaseCustomSidebarSection {
+            @service chatChannelsManager;
 
-              name = "user-threads";
+            // we only show `My Threads` link
+            hideSectionHeader = true;
 
-              // sidebar API doesn’t let you have undefined values
-              // even if you don't show the section’s header
-              title = "";
+            name = "user-threads";
 
-              get links() {
-                return [new SidebarChatMyThreadsSectionLink()];
-              }
+            // sidebar API doesn’t let you have undefined values
+            // even if you don't show the section’s header
+            title = "";
 
-              get text() {
-                return null;
-              }
-            };
+            get links() {
+              return [new SidebarChatMyThreadsSectionLink()];
+            }
 
-            return SidebarChatMyThreadsSection;
-          },
-          CHAT_PANEL
-        );
-      }
+            get text() {
+              return null;
+            }
+
+            get displaySection() {
+              return this.chatChannelsManager.hasThreadedChannels;
+            }
+          };
+
+          return SidebarChatMyThreadsSection;
+        },
+        CHAT_PANEL
+      );
 
       if (this.siteSettings.enable_public_channels) {
         api.addSidebarSection(
@@ -199,6 +198,7 @@ export default {
 
             const SidebarChatChannelsSection = class extends BaseCustomSidebarSection {
               @service currentUser;
+              @service chatStateManager;
 
               @tracked
               currentUserCanJoinPublicChannels =
@@ -261,8 +261,9 @@ export default {
 
               get displaySection() {
                 return (
-                  this.sectionLinks.length > 0 ||
-                  this.currentUserCanJoinPublicChannels
+                  this.chatStateManager.hasPreloadedChannels &&
+                  (this.sectionLinks.length > 0 ||
+                    this.currentUserCanJoinPublicChannels)
                 );
               }
             };
@@ -417,6 +418,7 @@ export default {
             @service modal;
             @service router;
             @service currentUser;
+            @service chatStateManager;
 
             @tracked
             userCanDirectMessage = this.chatService.userCanDirectMessage;
@@ -482,7 +484,10 @@ export default {
             }
 
             get displaySection() {
-              return this.sectionLinks.length > 0 || this.userCanDirectMessage;
+              return (
+                this.chatStateManager.hasPreloadedChannels &&
+                (this.sectionLinks.length > 0 || this.userCanDirectMessage)
+              );
             }
           };
 
diff --git a/plugins/chat/assets/javascripts/discourse/routes/chat-index.js b/plugins/chat/assets/javascripts/discourse/routes/chat-index.js
index 3a634394799..c80c51e6770 100644
--- a/plugins/chat/assets/javascripts/discourse/routes/chat-index.js
+++ b/plugins/chat/assets/javascripts/discourse/routes/chat-index.js
@@ -12,9 +12,8 @@ export default class ChatIndexRoute extends DiscourseRoute {
     if (!this.siteSettings.chat_threads_enabled) {
       return false;
     }
-    return this.currentUser?.chat_channels?.public_channels?.some(
-      (channel) => channel.threading_enabled
-    );
+
+    return this.chatChannelsManager.hasThreadedChannels;
   }
 
   get hasDirectMessages() {
@@ -25,7 +24,11 @@ export default class ChatIndexRoute extends DiscourseRoute {
     this.chat.activeChannel = null;
   }
 
-  redirect() {
+  async model() {
+    return await this.chat.loadChannels();
+  }
+
+  async redirect() {
     // on mobile redirect user to the first footer tab route
     if (this.site.mobileView) {
       if (
@@ -43,8 +46,8 @@ export default class ChatIndexRoute extends DiscourseRoute {
       }
     }
 
-    // We are on desktop. Check for a channel to enter and transition if so
-    const id = this.chat.getIdealFirstChannelId();
+    // We are on desktop. Check for last visited channel and transition if so
+    const id = this.currentUser.custom_fields.last_chat_channel_id;
     if (id) {
       return this.chatChannelsManager.find(id).then((c) => {
         return this.router.replaceWith("chat.channel", ...c.routeModels);
diff --git a/plugins/chat/assets/javascripts/discourse/services/chat-channels-manager.js b/plugins/chat/assets/javascripts/discourse/services/chat-channels-manager.js
index 078d9d6879a..1b853f3841d 100644
--- a/plugins/chat/assets/javascripts/discourse/services/chat-channels-manager.js
+++ b/plugins/chat/assets/javascripts/discourse/services/chat-channels-manager.js
@@ -33,6 +33,7 @@ export default class ChatChannelsManager extends Service {
     }
   }
 
+  @cached
   get channels() {
     return Object.values(this._cached);
   }
@@ -100,6 +101,13 @@ export default class ChatChannelsManager extends Service {
     delete this._cached[model.id];
   }
 
+  @cached
+  get hasThreadedChannels() {
+    return this.publicMessageChannels?.some(
+      (channel) => channel.threadingEnabled
+    );
+  }
+
   get allChannels() {
     return [...this.publicMessageChannels, ...this.directMessageChannels].sort(
       (a, b) => {
diff --git a/plugins/chat/assets/javascripts/discourse/services/chat-state-manager.js b/plugins/chat/assets/javascripts/discourse/services/chat-state-manager.js
index 9c8ae1008f4..205326f6577 100644
--- a/plugins/chat/assets/javascripts/discourse/services/chat-state-manager.js
+++ b/plugins/chat/assets/javascripts/discourse/services/chat-state-manager.js
@@ -30,6 +30,7 @@ export default class ChatStateManager extends Service {
   @tracked isSidePanelExpanded = false;
   @tracked isDrawerExpanded = false;
   @tracked isDrawerActive = false;
+  @tracked hasPreloadedChannels = false;
 
   @tracked _chatURL = null;
   @tracked _appURL = null;
diff --git a/plugins/chat/assets/javascripts/discourse/services/chat.js b/plugins/chat/assets/javascripts/discourse/services/chat.js
index d90ccd95967..e6ee02e7472 100644
--- a/plugins/chat/assets/javascripts/discourse/services/chat.js
+++ b/plugins/chat/assets/javascripts/discourse/services/chat.js
@@ -175,6 +175,32 @@ export default class Chat extends Service {
     this.set("isNetworkUnreliable", false);
   }
 
+  async loadChannels() {
+    // We want to be able to call this method multiple times, but only
+    // actually load the channels once. This is because we might call
+    // this method before the chat is fully initialized, and we don't
+    // want to load the channels multiple times in that case.
+    try {
+      if (this.chatStateManager.hasPreloadedChannels) {
+        return;
+      }
+
+      if (this.loadingChannels) {
+        return this.loadingChannels;
+      }
+
+      this.loadingChannels = new Promise((resolve) => {
+        this.chatApi.listCurrentUserChannels().then((result) => {
+          this.setupWithPreloadedChannels(result);
+          this.chatStateManager.hasPreloadedChannels = true;
+          resolve();
+        });
+      });
+    } catch (e) {
+      popupAjaxError(e);
+    }
+  }
+
   setupWithPreloadedChannels(channelsView) {
     this.chatSubscriptionsManager.startChannelsSubscriptions(
       channelsView.meta.message_bus_last_ids
@@ -294,68 +320,6 @@ export default class Chat extends Service {
     }
   }
 
-  getIdealFirstChannelId() {
-    // When user opens chat we need to give them the 'best' channel when they enter.
-    //
-    // Look for public channels with mentions. If one exists, enter that.
-    // Next best is a DM channel with unread messages.
-    // Next best is a public channel with unread messages.
-    // Then we fall back to the chat_default_channel_id site setting
-    // if that is present and in the list of channels the user can access.
-    // If none of these options exist, then we get the first public channel,
-    // or failing that the first DM channel.
-    // Defined in order of significance.
-    let publicChannelWithMention,
-      dmChannelWithUnread,
-      publicChannelWithUnread,
-      publicChannel,
-      dmChannel,
-      defaultChannel;
-
-    this.chatChannelsManager.channels.forEach((channel) => {
-      const membership = channel.currentUserMembership;
-
-      if (!membership.following) {
-        return;
-      }
-
-      if (channel.isDirectMessageChannel) {
-        if (!dmChannelWithUnread && channel.tracking.unreadCount > 0) {
-          dmChannelWithUnread = channel.id;
-        } else if (!dmChannel) {
-          dmChannel = channel.id;
-        }
-      } else {
-        if (membership.unread_mentions > 0) {
-          publicChannelWithMention = channel.id;
-          return; // <- We have a public channel with a mention. Break and return this.
-        } else if (
-          !publicChannelWithUnread &&
-          channel.tracking.unreadCount > 0
-        ) {
-          publicChannelWithUnread = channel.id;
-        } else if (
-          !defaultChannel &&
-          parseInt(this.siteSettings.chat_default_channel_id || 0, 10) ===
-            channel.id
-        ) {
-          defaultChannel = channel.id;
-        } else if (!publicChannel) {
-          publicChannel = channel.id;
-        }
-      }
-    });
-
-    return (
-      publicChannelWithMention ||
-      dmChannelWithUnread ||
-      publicChannelWithUnread ||
-      defaultChannel ||
-      publicChannel ||
-      dmChannel
-    );
-  }
-
   _fireOpenFloatAppEvent(channel, messageId = null) {
     messageId
       ? this.router.transitionTo(
diff --git a/plugins/chat/lib/chat/engine.rb b/plugins/chat/lib/chat/engine.rb
index 7c1191fc827..cdf2d3244e1 100644
--- a/plugins/chat/lib/chat/engine.rb
+++ b/plugins/chat/lib/chat/engine.rb
@@ -2,6 +2,7 @@
 
 module ::Chat
   HAS_CHAT_ENABLED = "has_chat_enabled"
+  LAST_CHAT_CHANNEL_ID = "last_chat_channel_id"
 
   class Engine < ::Rails::Engine
     engine_name PLUGIN_NAME
diff --git a/plugins/chat/plugin.rb b/plugins/chat/plugin.rb
index b2728cb7473..ec39914dd7f 100644
--- a/plugins/chat/plugin.rb
+++ b/plugins/chat/plugin.rb
@@ -49,6 +49,9 @@ after_initialize do
 
   register_category_custom_field_type(Chat::HAS_CHAT_ENABLED, :boolean)
 
+  register_user_custom_field_type(Chat::LAST_CHAT_CHANNEL_ID, :integer)
+  DiscoursePluginRegistry.serialized_current_user_fields << Chat::LAST_CHAT_CHANNEL_ID
+
   UserUpdater::OPTION_ATTR.push(:chat_enabled)
   UserUpdater::OPTION_ATTR.push(:only_chat_push_notifications)
   UserUpdater::OPTION_ATTR.push(:chat_sound)
@@ -210,29 +213,6 @@ after_initialize do
     ).exists?
   end
 
-  add_to_serializer(:current_user, :chat_channels) do
-    structured = Chat::ChannelFetcher.structured(self.scope)
-
-    structured[:unread_thread_overview] = ::Chat::TrackingStateReportQuery.call(
-      guardian: self.scope,
-      channel_ids: structured[:public_channels].map(&:id),
-      include_threads: true,
-      include_read: false,
-      include_last_reply_details: true,
-    ).thread_unread_overview_by_channel
-
-    category_ids = structured[:public_channels].map { |c| c.chatable_id }
-    post_allowed_category_ids =
-      Category.post_create_allowed(self.scope).where(id: category_ids).pluck(:id)
-
-    Chat::ChannelIndexSerializer.new(
-      structured,
-      scope: self.scope,
-      root: false,
-      post_allowed_category_ids: post_allowed_category_ids,
-    ).as_json
-  end
-
   add_to_serializer(
     :current_user,
     :chat_drafts,
diff --git a/plugins/chat/spec/plugin_spec.rb b/plugins/chat/spec/plugin_spec.rb
index 0ea5f678aeb..515979e4df6 100644
--- a/plugins/chat/spec/plugin_spec.rb
+++ b/plugins/chat/spec/plugin_spec.rb
@@ -273,75 +273,6 @@ describe Chat do
     end
   end
 
-  describe "current_user_serializer#chat_channels" do
-    before do
-      SiteSetting.chat_enabled = true
-      SiteSetting.chat_allowed_groups = Group::AUTO_GROUPS[:everyone]
-    end
-
-    fab!(:user)
-
-    let(:serializer) { CurrentUserSerializer.new(user, scope: Guardian.new(user)) }
-
-    it "returns the global presence channel state" do
-      expect(serializer.chat_channels[:global_presence_channel_state]).to be_present
-    end
-
-    context "when no channels exist" do
-      it "returns an empty array" do
-        expect(serializer.chat_channels[:direct_message_channels]).to eq([])
-        expect(serializer.chat_channels[:public_channels]).to eq([])
-      end
-    end
-
-    context "when followed direct message channels exist" do
-      fab!(:user_2) { Fabricate(:user) }
-      fab!(:channel) { Fabricate(:direct_message_channel, users: [user, user_2]) }
-
-      it "returns them" do
-        expect(serializer.chat_channels[:public_channels]).to eq([])
-        expect(serializer.chat_channels[:direct_message_channels].count).to eq(1)
-        expect(serializer.chat_channels[:direct_message_channels][0].id).to eq(channel.id)
-      end
-    end
-
-    context "when followed public channels exist" do
-      fab!(:channel) { Fabricate(:chat_channel) }
-
-      before do
-        Fabricate(:user_chat_channel_membership, user: user, chat_channel: channel, following: true)
-        Fabricate(:chat_channel)
-      end
-
-      it "returns them" do
-        expect(serializer.chat_channels[:direct_message_channels]).to eq([])
-        expect(serializer.chat_channels[:public_channels].count).to eq(1)
-        expect(serializer.chat_channels[:public_channels][0].id).to eq(channel.id)
-      end
-    end
-
-    context "when the category is restricted and user has readonly persmissions" do
-      fab!(:channel_1) { Fabricate(:chat_channel) }
-      fab!(:group_1) { Fabricate(:group) }
-      fab!(:private_channel_1) { Fabricate(:private_category_channel, group: group_1) }
-
-      before do
-        private_channel_1.chatable.category_groups.first.update!(
-          permission_type: CategoryGroup.permission_types[:readonly],
-        )
-        group_1.add(user)
-        channel_1.add(user)
-        private_channel_1.add(user)
-      end
-
-      it "doesn’t list the associated channel" do
-        expect(serializer.chat_channels[:public_channels].map(&:id)).to contain_exactly(
-          channel_1.id,
-        )
-      end
-    end
-  end
-
   describe "current_user_serializer#has_joinable_public_channels" do
     before do
       SiteSetting.chat_enabled = true
diff --git a/plugins/chat/spec/requests/chat/api/current_user_channels_spec.rb b/plugins/chat/spec/requests/chat/api/current_user_channels_spec.rb
index 12e9f187793..107ef22f240 100644
--- a/plugins/chat/spec/requests/chat/api/current_user_channels_spec.rb
+++ b/plugins/chat/spec/requests/chat/api/current_user_channels_spec.rb
@@ -43,93 +43,6 @@ describe Chat::Api::CurrentUserChannelsController do
 
         expect(response.parsed_body["public_channels"][0]["id"]).to eq(channel.id)
       end
-
-      it "returns limited access public channels with memberships" do
-        group = Fabricate(:group)
-        channel = Fabricate(:private_category_channel, group: group)
-        group.add(current_user)
-        channel.add(current_user)
-        get "/chat/api/me/channels"
-
-        expect(response.parsed_body["public_channels"][0]["id"]).to eq(channel.id)
-      end
-
-      it "doesn’t return unaccessible private channels" do
-        group = Fabricate(:group)
-        channel = Fabricate(:private_category_channel, group: group)
-        channel.add(current_user) # TODO: we should error here
-        get "/chat/api/me/channels"
-
-        expect(response.parsed_body["public_channels"]).to be_blank
-      end
-
-      it "returns dm channels you are part of" do
-        dm_channel = Fabricate(:direct_message_channel, users: [current_user])
-        get "/chat/api/me/channels"
-
-        expect(response.parsed_body["direct_message_channels"][0]["id"]).to eq(dm_channel.id)
-      end
-
-      it "doesn’t return dm channels from other users" do
-        Fabricate(:direct_message_channel)
-        get "/chat/api/me/channels"
-
-        expect(response.parsed_body["direct_message_channels"]).to be_blank
-      end
-
-      it "includes message bus ids" do
-        Fabricate(:direct_message_channel, users: [current_user])
-        channel = Fabricate(:category_channel)
-        channel.add(current_user)
-        get "/chat/api/me/channels"
-
-        expect(response.status).to eq(200)
-
-        response.parsed_body["meta"]["message_bus_last_ids"].tap do |ids|
-          expect(ids["channel_metadata"]).not_to eq(nil)
-          expect(ids["channel_edits"]).not_to eq(nil)
-          expect(ids["channel_status"]).not_to eq(nil)
-          expect(ids["new_channel"]).not_to eq(nil)
-          expect(ids["archive_status"]).not_to eq(nil)
-        end
-
-        response.parsed_body["public_channels"][0]["meta"]["message_bus_last_ids"].tap do |ids|
-          expect(ids["new_messages"]).not_to eq(nil)
-          expect(ids["new_mentions"]).not_to eq(nil)
-        end
-
-        response.parsed_body["direct_message_channels"][0]["meta"][
-          "message_bus_last_ids"
-        ].tap do |ids|
-          expect(ids["new_messages"]).not_to eq(nil)
-          expect(ids["new_mentions"]).not_to eq(nil)
-        end
-      end
-
-      context "when the chatable of a channel is destroyed" do
-        context "when the channel is a category" do
-          it "doesn’t return the channel" do
-            channel = Fabricate(:category_channel)
-            channel.add(current_user)
-            channel.chatable.destroy!
-            get "/chat/api/me/channels"
-
-            expect(response.status).to eq(200)
-            expect(response.parsed_body["public_channels"]).to be_blank
-          end
-        end
-
-        context "when the channel is a direct message" do
-          it "doesn’t return the channel" do
-            channel = Fabricate(:direct_message_channel, users: [current_user])
-            channel.chatable.destroy!
-            get "/chat/api/me/channels"
-
-            expect(response.status).to eq(200)
-            expect(response.parsed_body["direct_message_channels"]).to be_blank
-          end
-        end
-      end
     end
   end
 end
diff --git a/plugins/chat/spec/requests/core_ext/latest_performance_spec.rb b/plugins/chat/spec/requests/core_ext/latest_performance_spec.rb
deleted file mode 100644
index e33c08cd1c6..00000000000
--- a/plugins/chat/spec/requests/core_ext/latest_performance_spec.rb
+++ /dev/null
@@ -1,58 +0,0 @@
-# frozen_string_literal: true
-
-describe ListController do
-  fab!(:current_user) { Fabricate(:user) }
-
-  before do
-    SiteSetting.chat_enabled = true
-    sign_in(current_user)
-  end
-
-  describe "#latest" do
-    it "does not do N+1 chat_channel_archive queries based on the number of public and DM channels" do
-      user_1 = Fabricate(:user)
-      Fabricate(:direct_message_channel, users: [current_user, user_1])
-      public_channel_1 = Fabricate(:chat_channel)
-      public_channel_2 = Fabricate(:chat_channel)
-      public_channel_1.add(current_user)
-
-      # warm up
-      get "/latest.html"
-      expect(response.status).to eq(200)
-
-      initial_sql_queries_count =
-        track_sql_queries do
-          get "/latest.html"
-          expect(response.status).to eq(200)
-          expect(response.body).to have_tag("div#data-preloaded") do |element|
-            current_user_json =
-              JSON.parse(
-                JSON.parse(element.current_scope.attribute("data-preloaded").value)["currentUser"],
-              )
-            expect(current_user_json["chat_channels"]["direct_message_channels"].count).to eq(1)
-            expect(current_user_json["chat_channels"]["public_channels"].count).to eq(1)
-          end
-        end.count
-
-      public_channel_2.add(current_user)
-      user_2 = Fabricate(:user)
-      Fabricate(:direct_message_channel, users: [current_user, user_2])
-
-      new_sql_queries_count =
-        track_sql_queries do
-          get "/latest.html"
-          expect(response.status).to eq(200)
-          expect(response.body).to have_tag("div#data-preloaded") do |element|
-            current_user_json =
-              JSON.parse(
-                JSON.parse(element.current_scope.attribute("data-preloaded").value)["currentUser"],
-              )
-            expect(current_user_json["chat_channels"]["direct_message_channels"].count).to eq(2)
-            expect(current_user_json["chat_channels"]["public_channels"].count).to eq(2)
-          end
-        end.count
-
-      expect(new_sql_queries_count).to be <= initial_sql_queries_count
-    end
-  end
-end
diff --git a/plugins/chat/spec/services/chat/list_channel_messages_spec.rb b/plugins/chat/spec/services/chat/list_channel_messages_spec.rb
index 8f50bd783c4..02fe46f8489 100644
--- a/plugins/chat/spec/services/chat/list_channel_messages_spec.rb
+++ b/plugins/chat/spec/services/chat/list_channel_messages_spec.rb
@@ -211,4 +211,12 @@ RSpec.describe Chat::ListChannelMessages do
       ).of(Time.zone.now)
     end
   end
+
+  context "when update_user_last_channel" do
+    it "updates the custom field" do
+      expect { result }.to change { user.custom_fields[Chat::LAST_CHAT_CHANNEL_ID] }.from(nil).to(
+        channel.id,
+      )
+    end
+  end
 end
diff --git a/plugins/chat/spec/services/chat/list_user_channels_spec.rb b/plugins/chat/spec/services/chat/list_user_channels_spec.rb
new file mode 100644
index 00000000000..2a94b39a5ea
--- /dev/null
+++ b/plugins/chat/spec/services/chat/list_user_channels_spec.rb
@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+RSpec.describe Chat::ListUserChannels do
+  subject(:result) { described_class.call(params) }
+
+  fab!(:current_user) { Fabricate(:user) }
+  fab!(:channel_1) { Fabricate(:chat_channel) }
+
+  let(:guardian) { Guardian.new(current_user) }
+  let(:params) { { guardian: guardian } }
+
+  before { channel_1.add(current_user) }
+
+  it "returns the structured data" do
+    expect(result.structured[:post_allowed_category_ids]).to eq(nil)
+    expect(result.structured[:unread_thread_overview]).to eq({})
+    expect(result.structured[:memberships].to_a).to eq([channel_1.membership_for(current_user)])
+    expect(result.structured[:public_channels]).to eq([channel_1])
+    expect(result.structured[:direct_message_channels]).to eq([])
+    expect(result.structured[:tracking].channel_tracking[channel_1.id]).to eq(
+      { mention_count: 0, unread_count: 0 },
+    )
+  end
+
+  context "when the category is restricted and user has readonly permissions" do
+    fab!(:group_1) { Fabricate(:group) }
+    fab!(:private_channel_1) { Fabricate(:private_category_channel, group: group_1) }
+
+    before do
+      private_channel_1.chatable.category_groups.first.update!(
+        permission_type: CategoryGroup.permission_types[:readonly],
+      )
+      group_1.add(current_user)
+      private_channel_1.add(current_user)
+    end
+
+    it "doesn't list the associated channel" do
+      expect(result.structured[:public_channels]).to contain_exactly(channel_1)
+    end
+  end
+
+  context "when the category is restricted and user has permissions" do
+    fab!(:group_1) { Fabricate(:group) }
+    fab!(:private_channel_1) { Fabricate(:private_category_channel, group: group_1) }
+
+    before do
+      group_1.add(current_user)
+      private_channel_1.add(current_user)
+    end
+
+    it "lists the associated channel" do
+      expect(result.structured[:public_channels]).to contain_exactly(channel_1, private_channel_1)
+    end
+  end
+
+  it "doesn't return dm channels from other users" do
+    Fabricate(:direct_message_channel)
+
+    expect(result.structured[:direct_message_channels]).to eq([])
+  end
+
+  it "returns dm channels you are part of" do
+    dm_channel = Fabricate(:direct_message_channel, users: [current_user])
+
+    expect(result.structured[:direct_message_channels]).to eq([dm_channel])
+  end
+
+  it "doesnt return channels with destroyed chatable" do
+    dm_channel = Fabricate(:direct_message_channel, users: [current_user])
+    dm_channel.chatable.destroy!
+    channel_1.chatable.destroy!
+
+    expect(result.structured[:direct_message_channels]).to eq([])
+    expect(result.structured[:public_channels]).to eq([])
+  end
+end
diff --git a/plugins/chat/spec/system/chat_channel_spec.rb b/plugins/chat/spec/system/chat_channel_spec.rb
index 858b8da85de..ba19c13a6c8 100644
--- a/plugins/chat/spec/system/chat_channel_spec.rb
+++ b/plugins/chat/spec/system/chat_channel_spec.rb
@@ -184,7 +184,12 @@ RSpec.describe "Chat channel", type: :system do
       )
     end
 
-    before { channel_1.add(other_user) }
+    before do
+      SiteSetting.enable_user_status = true
+      current_user.set_status!("off to dentist", "tooth")
+      other_user.set_status!("surfing", "surfing_man")
+      channel_1.add(other_user)
+    end
 
     it "highlights the mentions" do
       chat_page.visit_channel(channel_1)
@@ -200,9 +205,6 @@ RSpec.describe "Chat channel", type: :system do
     end
 
     it "renders user status on mentions" do
-      SiteSetting.enable_user_status = true
-      current_user.set_status!("off to dentist", "tooth")
-      other_user.set_status!("surfing", "surfing_man")
       Fabricate(:user_chat_mention, user: current_user, chat_message: message)
       Fabricate(:user_chat_mention, user: other_user, chat_message: message)
 
@@ -215,6 +217,30 @@ RSpec.describe "Chat channel", type: :system do
         ".mention .user-status-message img[alt='#{other_user.user_status.emoji}']",
       )
     end
+
+    it "renders user status when expanding collapsed message" do
+      message_1 =
+        Fabricate(
+          :chat_message,
+          chat_channel: channel_1,
+          message: "hello @#{other_user.username}",
+          user: current_user,
+        )
+      chat_page.visit_channel(channel_1)
+
+      channel_page.messages.delete(message_1)
+      channel_page.messages.restore(message_1)
+
+      expect(page).to have_selector(
+        ".chat-message-container[data-id=\"#{message_1.id}\"] .mention .user-status-message img[alt='#{other_user.user_status.emoji}']",
+      )
+
+      other_user.set_status!("hello", "heart")
+
+      expect(page).to have_selector(
+        ".chat-message-container[data-id=\"#{message_1.id}\"] .mention .user-status-message img[alt='#{other_user.user_status.emoji}']",
+      )
+    end
   end
 
   context "when reply is right under" do
diff --git a/plugins/chat/spec/system/chat_new_message_spec.rb b/plugins/chat/spec/system/chat_new_message_spec.rb
index 1ee12b31d9f..a3c8d909286 100644
--- a/plugins/chat/spec/system/chat_new_message_spec.rb
+++ b/plugins/chat/spec/system/chat_new_message_spec.rb
@@ -30,8 +30,7 @@ RSpec.describe "Chat New Message from params", type: :system do
     it "redirects to chat channel if recipients param is missing" do
       visit("/chat/new-message")
 
-      # chat service selects public channel from getIdealFirstChannelId
-      expect(page).to have_current_path("/chat/c/#{public_channel.slug}/#{public_channel.id}")
+      expect(page).to have_no_current_path("/chat/new-message")
     end
   end
 
diff --git a/plugins/chat/spec/system/drawer_spec.rb b/plugins/chat/spec/system/drawer_spec.rb
index a35f9a49635..7f4a41d49d6 100644
--- a/plugins/chat/spec/system/drawer_spec.rb
+++ b/plugins/chat/spec/system/drawer_spec.rb
@@ -106,6 +106,7 @@ RSpec.describe "Drawer", type: :system do
     fab!(:user_1) { Fabricate(:user) }
 
     before do
+      current_user.upsert_custom_fields(::Chat::LAST_CHAT_CHANNEL_ID => channel_1.id)
       channel_1.add(current_user)
       channel_2.add(current_user)
       channel_1.add(user_1)
@@ -140,6 +141,7 @@ RSpec.describe "Drawer", type: :system do
     fab!(:channel) { Fabricate(:chat_channel) }
 
     before do
+      current_user.upsert_custom_fields(::Chat::LAST_CHAT_CHANNEL_ID => channel.id)
       channel.add(current_user)
       set_subfolder "/discuss"
     end
diff --git a/plugins/chat/spec/system/mention_warnings_spec.rb b/plugins/chat/spec/system/mention_warnings_spec.rb
index 20ce8fd79a8..3dfb0c30543 100644
--- a/plugins/chat/spec/system/mention_warnings_spec.rb
+++ b/plugins/chat/spec/system/mention_warnings_spec.rb
@@ -6,7 +6,7 @@ RSpec.describe "Mentions warnings", type: :system do
   fab!(:channel_2) { Fabricate(:chat_channel) }
 
   let(:chat_page) { PageObjects::Pages::Chat.new }
-  let(:chat_channel_page) { PageObjects::Pages::ChatChannel.new }
+  let(:channel_page) { PageObjects::Pages::ChatChannel.new }
 
   before do
     chat_system_bootstrap(current_user, [channel_1, channel_2])
@@ -22,7 +22,7 @@ RSpec.describe "Mentions warnings", type: :system do
 
         it "displays a warning" do
           chat_page.visit_channel(channel_1)
-          chat_channel_page.type_in_composer("@#{admin_mentionable_group.name} ")
+          channel_page.type_in_composer("@#{admin_mentionable_group.name} ")
 
           expect(page).to have_css(".chat-mention-warnings")
           expect(page.find(".chat-mention-warnings-list__simple")).to have_content(
@@ -46,7 +46,7 @@ RSpec.describe "Mentions warnings", type: :system do
 
           it "displays a warning" do
             chat_page.visit_channel(channel_1)
-            chat_channel_page.type_in_composer("@#{publicly_mentionable_group.name} ")
+            channel_page.type_in_composer("@#{publicly_mentionable_group.name} ")
 
             expect(page).to have_css(".chat-mention-warnings")
             expect(page.find(".chat-mention-warnings-list__simple")).to have_content(
@@ -60,13 +60,32 @@ RSpec.describe "Mentions warnings", type: :system do
 
           it "displays a warning" do
             chat_page.visit_channel(channel_1)
-            chat_channel_page.type_in_composer(
+            channel_page.type_in_composer(
               "@#{user_2.username} @#{publicly_mentionable_group.name} ",
             )
 
             expect(page).to have_css(".chat-mention-warnings")
             expect(page.find(".chat-mention-warnings-list__simple")).to be_present
           end
+
+          it "doesn’t count duplicates" do
+            chat_page.visit_channel(channel_1)
+            channel_page.type_in_composer("@#{user_2.username} @#{user_2.username} ")
+
+            expect(page).to have_no_css(".chat-mention-warnings")
+          end
+
+          it "doesn't consider code-blocks when counting mentions" do
+            raw =
+              "Hey @#{user_2.username}\n\n```\ndef foo\n  @#{publicly_mentionable_group.name} = true\nend\n```\n"
+            message_1 =
+              Fabricate(:chat_message, user: current_user, chat_channel: channel_1, message: raw)
+            chat_page.visit_channel(channel_1)
+
+            channel_page.messages.edit(message_1)
+
+            expect(page).to have_no_css(".chat-mention-warnings")
+          end
         end
       end
     end
@@ -77,7 +96,7 @@ RSpec.describe "Mentions warnings", type: :system do
       %w[@here @all].each do |mention_text|
         it "displays a warning" do
           chat_page.visit_channel(channel_1)
-          chat_channel_page.type_in_composer(mention_text)
+          channel_page.type_in_composer(mention_text)
 
           expect(page).to have_css(".chat-mention-warnings")
           expect(page.find(".chat-mention-warnings-list__simple")).to be_present
diff --git a/plugins/chat/spec/system/navigation_spec.rb b/plugins/chat/spec/system/navigation_spec.rb
index 8ef19f21469..22104c3a79b 100644
--- a/plugins/chat/spec/system/navigation_spec.rb
+++ b/plugins/chat/spec/system/navigation_spec.rb
@@ -18,6 +18,7 @@ RSpec.describe "Navigation", type: :system do
   let(:chat_drawer_page) { PageObjects::Pages::ChatDrawer.new }
 
   before do
+    current_user.upsert_custom_fields(::Chat::LAST_CHAT_CHANNEL_ID => category_channel.id)
     chat_system_bootstrap(current_user, [category_channel, category_channel_2])
     current_user.user_option.update(
       chat_separate_sidebar_mode: UserOption.chat_separate_sidebar_modes[:never],
@@ -83,13 +84,11 @@ RSpec.describe "Navigation", type: :system do
       expect(page).to have_current_path(
         chat.channel_path(category_channel.slug, category_channel.id),
       )
-      expect(page).to have_css("html.has-full-page-chat")
-      expect(page).to have_css(".chat-message-container[data-id='#{message.id}']")
     end
   end
 
   context "when visiting mobile only routes on desktop" do
-    it "redirects /chat/channels to ideal first channel" do
+    it "redirects /chat/channels to browse" do
       visit("/chat/channels")
 
       expect(page).to have_current_path(
@@ -97,7 +96,7 @@ RSpec.describe "Navigation", type: :system do
       )
     end
 
-    it "redirects /chat/direct-messages to ideal first channel" do
+    it "redirects /chat/direct-messages to browse" do
       visit("/chat/direct-messages")
 
       expect(page).to have_current_path(
@@ -153,7 +152,9 @@ RSpec.describe "Navigation", type: :system do
       chat_page.open
       chat_page.minimize_full_page
 
-      expect(page).to have_current_path(latest_path)
+      expect(page).to have_current_path(
+        chat.channel_path(category_channel.slug, category_channel.id),
+      )
     end
   end
 
diff --git a/plugins/chat/spec/system/removing_channel_spec.rb b/plugins/chat/spec/system/removing_channel_spec.rb
index b52bdac3442..dd41407c280 100644
--- a/plugins/chat/spec/system/removing_channel_spec.rb
+++ b/plugins/chat/spec/system/removing_channel_spec.rb
@@ -36,7 +36,10 @@ RSpec.describe "Removing channel", type: :system do
     fab!(:channel_1) { Fabricate(:chat_channel) }
     fab!(:channel_2) { Fabricate(:direct_message_channel, users: [current_user, Fabricate(:user)]) }
 
-    before { channel_1.add(current_user) }
+    before do
+      current_user.upsert_custom_fields(::Chat::LAST_CHAT_CHANNEL_ID => channel_1.id)
+      channel_1.add(current_user)
+    end
 
     it "redirects to another followed channgel" do
       chat_page.visit_channel(channel_2)
diff --git a/plugins/chat/test/javascripts/acceptance/hashtag-css-generator-test.js b/plugins/chat/test/javascripts/acceptance/hashtag-css-generator-test.js
index 0827ad711ab..24615133d25 100644
--- a/plugins/chat/test/javascripts/acceptance/hashtag-css-generator-test.js
+++ b/plugins/chat/test/javascripts/acceptance/hashtag-css-generator-test.js
@@ -15,49 +15,54 @@ acceptance("Chat | Hashtag CSS Generator", function (needs) {
   needs.settings({ chat_enabled: true });
   needs.user({
     has_chat_enabled: true,
-    chat_channels: {
-      public_channels: [
-        {
-          id: 44,
-          chatable_id: 1,
-          chatable_type: "Category",
-          meta: { message_bus_last_ids: {} },
-          current_user_membership: { following: true },
-          chatable: category1,
-        },
-        {
-          id: 74,
-          chatable_id: 2,
-          chatable_type: "Category",
-          meta: { message_bus_last_ids: {} },
-          current_user_membership: { following: true },
-          chatable: category2,
-        },
-        {
-          id: 88,
-          chatable_id: 4,
-          chatable_type: "Category",
-          meta: { message_bus_last_ids: {} },
-          current_user_membership: { following: true },
-          chatable: category3,
-        },
-      ],
-      direct_message_channels: [],
-      meta: { message_bus_last_ids: {} },
-      tracking: {
-        channel_tracking: {
-          44: { unread_count: 0, mention_count: 0 },
-          74: { unread_count: 0, mention_count: 0 },
-          88: { unread_count: 0, mention_count: 0 },
-        },
-        thread_tracking: {},
-      },
-    },
   });
   needs.site({
     categories: [category1, category2, category3],
   });
 
+  needs.pretender((server, helper) => {
+    server.get("/chat/api/me/channels", () =>
+      helper.response({
+        public_channels: [
+          {
+            id: 44,
+            chatable_id: 1,
+            chatable_type: "Category",
+            meta: { message_bus_last_ids: {} },
+            current_user_membership: { following: true },
+            chatable: category1,
+          },
+          {
+            id: 74,
+            chatable_id: 2,
+            chatable_type: "Category",
+            meta: { message_bus_last_ids: {} },
+            current_user_membership: { following: true },
+            chatable: category2,
+          },
+          {
+            id: 88,
+            chatable_id: 4,
+            chatable_type: "Category",
+            meta: { message_bus_last_ids: {} },
+            current_user_membership: { following: true },
+            chatable: category3,
+          },
+        ],
+        direct_message_channels: [],
+        meta: { message_bus_last_ids: {} },
+        tracking: {
+          channel_tracking: {
+            44: { unread_count: 0, mention_count: 0 },
+            74: { unread_count: 0, mention_count: 0 },
+            88: { unread_count: 0, mention_count: 0 },
+          },
+          thread_tracking: {},
+        },
+      })
+    );
+  });
+
   test("hashtag CSS classes are generated", async function (assert) {
     await visit("/");
     const cssTag = document.querySelector("style#hashtag-css-generator");
@@ -66,10 +71,7 @@ acceptance("Chat | Hashtag CSS Generator", function (needs) {
       ".hashtag-category-badge { background-color: var(--primary-medium); }\n" +
         ".hashtag-color--category-1 { background-color: #ff0000; }\n" +
         ".hashtag-color--category-2 { background-color: #333; }\n" +
-        ".hashtag-color--category-4 { background-color: #2B81AF; }\n" +
-        ".d-icon.hashtag-color--channel-44 { color: #ff0000 }\n" +
-        ".d-icon.hashtag-color--channel-74 { color: #333 }\n" +
-        ".d-icon.hashtag-color--channel-88 { color: #2B81AF }"
+        ".hashtag-color--category-4 { background-color: #2B81AF; }"
     );
   });
 });
diff --git a/plugins/chat/test/javascripts/acceptance/mentions-test.js b/plugins/chat/test/javascripts/acceptance/mentions-test.js
deleted file mode 100644
index 46e9e9fb58c..00000000000
--- a/plugins/chat/test/javascripts/acceptance/mentions-test.js
+++ /dev/null
@@ -1,107 +0,0 @@
-import { fillIn, visit } from "@ember/test-helpers";
-import { test } from "qunit";
-import pretender, { response } from "discourse/tests/helpers/create-pretender";
-import { acceptance } from "discourse/tests/helpers/qunit-helpers";
-
-acceptance("Chat | Mentions", function (needs) {
-  const channelId = 1;
-  const actingUser = {
-    id: 1,
-    username: "acting_user",
-  };
-  const channel = {
-    id: channelId,
-    chatable_id: 1,
-    chatable_type: "Category",
-    meta: { message_bus_last_ids: {}, can_delete_self: true },
-    current_user_membership: { following: true },
-    allow_channel_wide_mentions: false,
-    chatable: { id: 1 },
-    title: "Some title",
-  };
-
-  needs.settings({ chat_enabled: true });
-
-  needs.user({
-    ...actingUser,
-    has_chat_enabled: true,
-    chat_channels: {
-      public_channels: [channel],
-      direct_message_channels: [],
-      meta: { message_bus_last_ids: {} },
-      tracking: {},
-    },
-  });
-
-  needs.hooks.beforeEach(function () {
-    pretender.post(`/chat/drafts`, () => response({}));
-    pretender.get(`/chat/api/channels/${channelId}/messages`, () =>
-      response({
-        messages: [],
-        meta: {
-          can_load_more_future: false,
-        },
-      })
-    );
-    pretender.get("/chat/api/mentions/groups.json", () =>
-      response({
-        unreachable: [],
-        over_members_limit: [],
-        invalid: ["and"],
-      })
-    );
-  });
-
-  test("shows warning when mention limit exceeded", async function (assert) {
-    this.siteSettings.max_mentions_per_chat_message = 2;
-
-    await visit(`/chat/c/-/${channelId}`);
-    await fillIn(".chat-composer__input", `Hey @user1 @user2 @user3`);
-
-    assert.dom(".chat-mention-warnings").exists();
-  });
-
-  test("shows warning for @here mentions when channel-wide mentions are disabled", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-    await fillIn(".chat-composer__input", `Hey @here`);
-
-    assert.dom(".chat-mention-warnings").exists();
-  });
-
-  test("shows warning for @all mention when channel-wide mentions are disabled", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-    await fillIn(".chat-composer__input", `Hey @all`);
-
-    assert.dom(".chat-mention-warnings").exists();
-  });
-
-  test("ignores duplicates when counting mentions", async function (assert) {
-    this.siteSettings.max_mentions_per_chat_message = 2;
-
-    await visit(`/chat/c/-/${channelId}`);
-    const mention = `@user1`;
-    await fillIn(
-      ".chat-composer__input",
-      `Hey ${mention} ${mention} ${mention}`
-    );
-
-    assert.dom(".chat-mention-warnings").doesNotExist();
-  });
-
-  test("doesn't consider code-blocks when counting mentions", async function (assert) {
-    this.siteSettings.max_mentions_per_chat_message = 2;
-
-    await visit(`/chat/c/-/${channelId}`);
-    // since @bar is inside a code-block it shouldn't be considered a mention
-    const message = `Hey @user1 @user2
-    \`\`\`
-      def foo
-        @bar = true
-      end
-    \`\`\`
-    `;
-    await fillIn(".chat-composer__input", message);
-
-    assert.dom(".chat-mention-warnings").doesNotExist();
-  });
-});
diff --git a/plugins/chat/test/javascripts/acceptance/user-status-on-mentions-test.js b/plugins/chat/test/javascripts/acceptance/user-status-on-mentions-test.js
deleted file mode 100644
index 257af7c073c..00000000000
--- a/plugins/chat/test/javascripts/acceptance/user-status-on-mentions-test.js
+++ /dev/null
@@ -1,332 +0,0 @@
-import { click, triggerEvent, visit, waitFor } from "@ember/test-helpers";
-import { skip, test } from "qunit";
-import pretender, { response } from "discourse/tests/helpers/create-pretender";
-import {
-  acceptance,
-  loggedInUser,
-  publishToMessageBus,
-  query,
-  simulateKeys,
-} from "discourse/tests/helpers/qunit-helpers";
-
-acceptance("Chat | User status on mentions", function (needs) {
-  const channelId = 1;
-  const messageId = 1;
-  const actingUser = {
-    id: 1,
-    username: "acting_user",
-  };
-  const mentionedUser1 = {
-    id: 1000,
-    username: "user1",
-    status: {
-      description: "surfing",
-      emoji: "surfing_man",
-    },
-  };
-  const mentionedUser2 = {
-    id: 2000,
-    username: "user2",
-    status: {
-      description: "vacation",
-      emoji: "desert_island",
-    },
-  };
-  const mentionedUser3 = {
-    id: 3000,
-    username: "user3",
-    status: {
-      description: "off to dentist",
-      emoji: "tooth",
-    },
-  };
-  const message = {
-    id: messageId,
-    message: `Hey @${mentionedUser1.username}`,
-    cooked: `<p>Hey <a class="mention" href="/u/${mentionedUser1.username}">@${mentionedUser1.username}</a></p>`,
-    mentioned_users: [mentionedUser1],
-    user: actingUser,
-    created_at: "2020-08-04T15:00:00.000Z",
-  };
-  const newStatus = {
-    description: "working remotely",
-    emoji: "house",
-  };
-  const channel = {
-    id: channelId,
-    chatable_id: 1,
-    chatable_type: "Category",
-    title: "A category channel",
-    meta: { message_bus_last_ids: {}, can_delete_self: true },
-    current_user_membership: { following: true },
-    chatable: { id: 1 },
-  };
-
-  needs.settings({ chat_enabled: true });
-
-  needs.user({
-    ...actingUser,
-    has_chat_enabled: true,
-    chat_channels: {
-      public_channels: [channel],
-      direct_message_channels: [],
-      meta: { message_bus_last_ids: {} },
-      tracking: {},
-    },
-  });
-
-  needs.hooks.beforeEach(function () {
-    pretender.post(`/chat/1`, () => response({}));
-    pretender.put(`/chat/1/edit/${messageId}`, () => response({}));
-    pretender.post(`/chat/drafts`, () => response({}));
-    pretender.put(`/chat/api/channels/1/read/1`, () => response({}));
-    pretender.get(`/chat/api/channels/1/messages`, () =>
-      response({
-        messages: [message],
-        meta: {
-          can_load_more_future: false,
-        },
-      })
-    );
-    pretender.delete(`/chat/api/channels/1/messages/${messageId}`, () =>
-      response({})
-    );
-    pretender.put(`/chat/api/channels/1/messages/${messageId}/restore`, () =>
-      response({})
-    );
-
-    pretender.get("/u/search/users", () =>
-      response({
-        users: [mentionedUser2, mentionedUser3],
-      })
-    );
-
-    pretender.get("/chat/api/mentions/groups.json", () =>
-      response({
-        unreachable: [],
-        over_members_limit: [],
-        invalid: ["and"],
-      })
-    );
-  });
-
-  skip("just posted messages | it shows status on mentions ", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-    await typeWithAutocompleteAndSend(`mentioning @${mentionedUser2.username}`);
-    assertStatusIsRendered(
-      assert,
-      statusSelector(mentionedUser2.username),
-      mentionedUser2.status
-    );
-  });
-
-  skip("just posted messages | it updates status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-    await typeWithAutocompleteAndSend(`mentioning @${mentionedUser2.username}`);
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser2.id]: newStatus,
-    });
-
-    const selector = statusSelector(mentionedUser2.username);
-    await waitFor(selector);
-    assertStatusIsRendered(assert, selector, newStatus);
-  });
-
-  skip("just posted messages | it deletes status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await typeWithAutocompleteAndSend(`mentioning @${mentionedUser2.username}`);
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser2.id]: null,
-    });
-
-    const selector = statusSelector(mentionedUser2.username);
-    await waitFor(selector, { count: 0 });
-    assert.dom(selector).doesNotExist("status is deleted");
-  });
-
-  skip("edited messages | it shows status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await editMessage(
-      ".chat-message-content",
-      `mentioning @${mentionedUser3.username}`
-    );
-
-    assertStatusIsRendered(
-      assert,
-      statusSelector(mentionedUser3.username),
-      mentionedUser3.status
-    );
-  });
-
-  skip("edited messages | it updates status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-    await editMessage(
-      ".chat-message-content",
-      `mentioning @${mentionedUser3.username}`
-    );
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser3.id]: newStatus,
-    });
-
-    const selector = statusSelector(mentionedUser3.username);
-    await waitFor(selector);
-    assertStatusIsRendered(assert, selector, newStatus);
-  });
-
-  skip("edited messages | it deletes status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await editMessage(
-      ".chat-message-content",
-      `mentioning @${mentionedUser3.username}`
-    );
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser3.id]: null,
-    });
-
-    const selector = statusSelector(mentionedUser3.username);
-    await waitFor(selector, { count: 0 });
-    assert.dom(selector).doesNotExist("status is deleted");
-  });
-
-  test("deleted messages | it shows status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await deleteMessage(".chat-message-content");
-    await click(".chat-message-expand");
-
-    assertStatusIsRendered(
-      assert,
-      statusSelector(mentionedUser1.username),
-      mentionedUser1.status
-    );
-  });
-
-  test("deleted messages | it updates status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await deleteMessage(".chat-message-content");
-    await click(".chat-message-expand");
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser1.id]: newStatus,
-    });
-
-    const selector = statusSelector(mentionedUser1.username);
-    await waitFor(selector);
-    assertStatusIsRendered(assert, selector, newStatus);
-  });
-
-  test("deleted messages | it deletes status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await deleteMessage(".chat-message-content");
-    await click(".chat-message-expand");
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser1.id]: null,
-    });
-
-    const selector = statusSelector(mentionedUser1.username);
-    await waitFor(selector, { count: 0 });
-    assert.dom(selector).doesNotExist("status is deleted");
-  });
-
-  test("restored messages | it shows status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await deleteMessage(".chat-message-content");
-    await restoreMessage(".chat-message-text.-deleted");
-
-    assertStatusIsRendered(
-      assert,
-      statusSelector(mentionedUser1.username),
-      mentionedUser1.status
-    );
-  });
-
-  test("restored messages | it updates status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await deleteMessage(".chat-message-content");
-    await restoreMessage(".chat-message-text.-deleted");
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser1.id]: newStatus,
-    });
-
-    const selector = statusSelector(mentionedUser1.username);
-    await waitFor(selector);
-    assertStatusIsRendered(assert, selector, newStatus);
-  });
-
-  test("restored messages | it deletes status on mentions", async function (assert) {
-    await visit(`/chat/c/-/${channelId}`);
-
-    await deleteMessage(".chat-message-content");
-    await restoreMessage(".chat-message-text.-deleted");
-
-    loggedInUser().appEvents.trigger("user-status:changed", {
-      [mentionedUser1.id]: null,
-    });
-
-    const selector = statusSelector(mentionedUser1.username);
-    await waitFor(selector, { count: 0 });
-    assert.dom(selector).doesNotExist("status is deleted");
-  });
-
-  function assertStatusIsRendered(assert, selector, status) {
-    assert
-      .dom(selector)
-      .exists("status is rendered")
-      .hasAttribute(
-        "src",
-        new RegExp(`${status.emoji}.png`),
-        "status emoji is updated"
-      );
-  }
-
-  async function deleteMessage(messageSelector) {
-    await triggerEvent(query(messageSelector), "mouseenter");
-    await click(".more-buttons .select-kit-header-wrapper");
-    await click(".select-kit-collection .select-kit-row[data-value='delete']");
-    await publishToMessageBus(`/chat/${channelId}`, {
-      type: "delete",
-      deleted_id: messageId,
-      deleted_at: "2022-01-01T08:00:00.000Z",
-    });
-  }
-
-  async function editMessage(messageSelector, text) {
-    await triggerEvent(query(messageSelector), "mouseenter");
-    await click(".more-buttons .select-kit-header-wrapper");
-    await click(".select-kit-collection .select-kit-row[data-value='edit']");
-    await typeWithAutocompleteAndSend(text);
-  }
-
-  async function restoreMessage(messageSelector) {
-    await triggerEvent(query(messageSelector), "mouseenter");
-    await click(".more-buttons .select-kit-header-wrapper");
-    await click(".select-kit-collection .select-kit-row[data-value='restore']");
-    await publishToMessageBus(`/chat/${channelId}`, {
-      type: "restore",
-      chat_message: message,
-    });
-  }
-
-  async function typeWithAutocompleteAndSend(text) {
-    await simulateKeys(query(".chat-composer__input"), text);
-    await click(".autocomplete.ac-user .selected");
-    await click(".chat-composer-button.-send");
-  }
-
-  function statusSelector(username) {
-    return `.mention[href='/u/${username}'] .user-status-message img`;
-  }
-});
diff --git a/plugins/chat/test/javascripts/components/chat-channel-test.js b/plugins/chat/test/javascripts/components/chat-channel-test.js
index 66dea083deb..69c9bd08992 100644
--- a/plugins/chat/test/javascripts/components/chat-channel-test.js
+++ b/plugins/chat/test/javascripts/components/chat-channel-test.js
@@ -51,6 +51,12 @@ module(
           meta: { can_delete_self: true },
         })
       );
+      pretender.get(`/chat/api/me/channels`, () =>
+        response({
+          direct_message_channels: [],
+          public_channels: [],
+        })
+      );
 
       this.channel = fabricators.channel({
         id: channelId,