diff --git a/addons/im_livechat/static/src/composer/composer_patch.js b/addons/im_livechat/static/src/composer/composer_patch.js
index 0ff656d2ff1..5620709b42f 100644
--- a/addons/im_livechat/static/src/composer/composer_patch.js
+++ b/addons/im_livechat/static/src/composer/composer_patch.js
@@ -30,11 +30,9 @@ patch(Composer.prototype, {
         return (
             this.thread?.type === "livechat" &&
             !this.env.inChatWindow &&
-            Object.values(this.store.discuss.livechat.threads).some((localId) => {
-                return (
-                    localId !== this.thread.localId && this.store.Thread.records[localId].isUnread
-                );
-            })
+            this.store.discuss.livechat.threads.some(
+                (thread) => thread.notEq(this.thread) && thread.isUnread
+            )
         );
     },
 });
diff --git a/addons/im_livechat/static/src/core/@types/models.d.ts b/addons/im_livechat/static/src/core/@types/models.d.ts
new file mode 100644
index 00000000000..3a831742636
--- /dev/null
+++ b/addons/im_livechat/static/src/core/@types/models.d.ts
@@ -0,0 +1,5 @@
+declare module "models" {
+    export interface DiscussApp {
+        livechat: DiscussAppCategory,
+    }
+}
diff --git a/addons/im_livechat/static/src/core/store_service_patch.js b/addons/im_livechat/static/src/core/discuss_app_model_patch.js
similarity index 54%
rename from addons/im_livechat/static/src/core/store_service_patch.js
rename to addons/im_livechat/static/src/core/discuss_app_model_patch.js
index c859043644a..0f7d73b5fff 100644
--- a/addons/im_livechat/static/src/core/store_service_patch.js
+++ b/addons/im_livechat/static/src/core/discuss_app_model_patch.js
@@ -1,14 +1,15 @@
 /* @odoo-module */
 
-import { Store } from "@mail/core/common/store_service";
+import { DiscussApp } from "@mail/core/common/discuss_app_model";
+import { Record } from "@mail/core/common/record";
 
 import { _t } from "@web/core/l10n/translation";
 import { patch } from "@web/core/utils/patch";
 
-patch(Store.prototype, {
-    setup(env) {
-        super.setup(env);
-        this.discuss.livechat = {
+patch(DiscussApp, {
+    new(data) {
+        const res = super.new(data);
+        res.livechat = this.store.DiscussAppCategory.insert({
             extraClass: "o-mail-DiscussSidebarCategory-livechat",
             id: "livechat",
             name: _t("Livechat"),
@@ -16,7 +17,14 @@ patch(Store.prototype, {
             canView: false,
             canAdd: false,
             serverStateKey: "is_discuss_sidebar_category_livechat_open",
-            threads: [], // list of ids
-        };
+        });
+        return res;
+    },
+});
+
+patch(DiscussApp.prototype, {
+    setup(env) {
+        super.setup(env);
+        this.livechat = Record.one("DiscussAppCategory");
     },
 });
diff --git a/addons/im_livechat/static/src/core/thread_model_patch.js b/addons/im_livechat/static/src/core/thread_model_patch.js
index 1a63059c82f..62658754c94 100644
--- a/addons/im_livechat/static/src/core/thread_model_patch.js
+++ b/addons/im_livechat/static/src/core/thread_model_patch.js
@@ -22,7 +22,7 @@ patch(Thread, {
                 });
             }
             if (isUnknown) {
-                this.store.discuss.livechat.threads.push(thread.localId);
+                this.store.discuss.livechat.threads.push(thread);
                 this.env.services["mail.thread"].sortChannels();
             }
         }
diff --git a/addons/im_livechat/static/src/core/thread_service_patch.js b/addons/im_livechat/static/src/core/thread_service_patch.js
index c03c01ca03a..0f28e463e63 100644
--- a/addons/im_livechat/static/src/core/thread_service_patch.js
+++ b/addons/im_livechat/static/src/core/thread_service_patch.js
@@ -2,7 +2,6 @@
 
 import { DEFAULT_AVATAR } from "@mail/core/common/persona_service";
 import { ThreadService } from "@mail/core/common/thread_service";
-import { removeFromArray } from "@mail/utils/common/arrays";
 
 import { patch } from "@web/core/utils/patch";
 
@@ -18,12 +17,6 @@ patch(ThreadService.prototype, {
             this.store.discuss.activeTab = "livechat";
         }
     },
-    remove(thread) {
-        if (thread.type === "livechat") {
-            removeFromArray(this.store.discuss.livechat.threads, thread.localId);
-        }
-        super.remove(thread);
-    },
 
     canLeave(thread) {
         return thread.type !== "livechat" && super.canLeave(thread);
@@ -46,27 +39,18 @@ patch(ThreadService.prototype, {
     sortChannels() {
         super.sortChannels();
         // Live chats are sorted by most recent interest date time in the sidebar.
-        this.store.discuss.livechat.threads.sort((localId_1, localId_2) => {
-            const thread1 = this.store.Thread.records[localId_1];
-            const thread2 = this.store.Thread.records[localId_2];
-            return thread2.lastInterestDateTime?.ts - thread1.lastInterestDateTime?.ts;
-        });
+        this.store.discuss.livechat.threads.sort(
+            (t1, t2) => t2.lastInterestDateTime?.ts - t1.lastInterestDateTime?.ts
+        );
     },
 
     /**
      * @returns {boolean} Whether the livechat thread changed.
      */
     goToOldestUnreadLivechatThread() {
-        const oldestUnreadThread =
-            this.store.Thread.records[
-                Object.values(this.store.discuss.livechat.threads)
-                    .filter((localId) => this.store.Thread.records[localId].isUnread)
-                    .sort(
-                        (localId_1, localId_2) =>
-                            this.store.Thread.records[localId_1].lastInterestDateTime?.ts -
-                            this.store.Thread.records[localId_2].lastInterestDateTime?.ts
-                    )[0]
-            ];
+        const oldestUnreadThread = this.store.discuss.livechat.threads
+            .filter((thread) => thread.isUnread)
+            .sort((t1, t2) => t1.lastInterestDateTime?.ts - t2.lastInterestDateTime?.ts)[0];
         if (!oldestUnreadThread) {
             return false;
         }
diff --git a/addons/im_livechat/static/src/discuss_app/discuss_sidebar_categories_livechat.js b/addons/im_livechat/static/src/discuss_app/discuss_sidebar_categories_livechat.js
index 3e36d0dad60..4233cba978f 100644
--- a/addons/im_livechat/static/src/discuss_app/discuss_sidebar_categories_livechat.js
+++ b/addons/im_livechat/static/src/discuss_app/discuss_sidebar_categories_livechat.js
@@ -5,10 +5,7 @@ import { discussSidebarCategoriesRegistry } from "@mail/discuss/core/web/discuss
 discussSidebarCategoriesRegistry.add(
     "livechats",
     {
-        predicate: (store) =>
-            store.discuss.livechat.threads.some(
-                (localId) => store.Thread.records[localId]?.is_pinned
-            ),
+        predicate: (store) => store.discuss.livechat.threads.some((thread) => thread?.is_pinned),
         value: (store) => store.discuss.livechat,
     },
     { sequence: 20 }
diff --git a/addons/im_livechat/static/src/embed/core/livechat_service.js b/addons/im_livechat/static/src/embed/core/livechat_service.js
index 51ea76cfb02..0d85c69a9b4 100644
--- a/addons/im_livechat/static/src/embed/core/livechat_service.js
+++ b/addons/im_livechat/static/src/embed/core/livechat_service.js
@@ -157,7 +157,7 @@ export class LivechatService {
             (c) => c.thread.id === this.TEMPORARY_ID
         );
         if (chatWindow) {
-            this.env.services["mail.thread"].remove(chatWindow.thread);
+            chatWindow.thread?.delete();
             if (!this.thread) {
                 this.chatWindowService.close(chatWindow);
                 return;
diff --git a/addons/mail/static/src/core/common/@types/models.d.ts b/addons/mail/static/src/core/common/@types/models.d.ts
index 18635c620b3..ba73317f735 100644
--- a/addons/mail/static/src/core/common/@types/models.d.ts
+++ b/addons/mail/static/src/core/common/@types/models.d.ts
@@ -3,6 +3,8 @@ declare module "models" {
     import { CannedResponse as CannedResponseClass } from "@mail/core/common/canned_response_model";
     import { ChannelMember as ChannelMemberClass } from "@mail/core/common/channel_member_model";
     import { Composer as ComposerClass } from "@mail/core/common/composer_model";
+    import { DiscussApp as DiscussAppClass } from "@mail/core/common/discuss_app_model";
+    import { DiscussAppCategory as DiscussAppCategoryClass } from "@mail/core/common/discuss_app_category_model";
     import { Follower as FollowerClass } from "@mail/core/common/follower_model";
     import { LinkPreview as LinkPreviewClass } from "@mail/core/common/link_preview_model";
     import { Message as MessageClass } from "@mail/core/common/message_model";
@@ -16,6 +18,8 @@ declare module "models" {
     export interface Attachment extends CannedResponseClass {}
     export interface ChannelMember extends ChannelMemberClass {}
     export interface Composer extends ComposerClass {}
+    export interface DiscussApp extends DiscussAppClass {}
+    export interface DiscussAppCategory extends DiscussAppCategoryClass {}
     export interface Follower extends FollowerClass {}
     export interface LinkPreview extends LinkPreviewClass {}
     export interface Message extends MessageClass {}
@@ -30,6 +34,8 @@ declare module "models" {
         "CannedResponse": CannedResponse,
         "ChannelMember": ChannelMember,
         "Composer": Composer,
+        "DiscussApp": DiscussApp,
+        "DiscussAppCategory": DiscussAppCategory,
         "Follower": Follower,
         "LinkPreview": LinkPreview,
         "Message": Message,
diff --git a/addons/mail/static/src/core/common/discuss.js b/addons/mail/static/src/core/common/discuss.js
index 55e0d45bbf4..8170a2a7bba 100644
--- a/addons/mail/static/src/core/common/discuss.js
+++ b/addons/mail/static/src/core/common/discuss.js
@@ -83,7 +83,7 @@ export class Discuss extends Component {
     }
 
     get thread() {
-        return this.store.Thread.records[this.store.discuss.threadLocalId];
+        return this.store.discuss.thread;
     }
 
     async onFileUploaded(file) {
diff --git a/addons/mail/static/src/core/common/discuss.xml b/addons/mail/static/src/core/common/discuss.xml
index 8c7d8dc6518..16ad3ecd1a6 100644
--- a/addons/mail/static/src/core/common/discuss.xml
+++ b/addons/mail/static/src/core/common/discuss.xml
@@ -93,7 +93,7 @@
 <t t-name="mail.MobileMailbox">
     <button class="btn btn-secondary flex-grow-1 p-2"
         t-att-class="{
-            'active o-active shadow-none': store.discuss.threadLocalId === mailbox.localId,
+            'active o-active shadow-none': mailbox.eq(store.discuss.thread),
         }" t-on-click="() => this.threadService.setDiscussThread(mailbox)" t-esc="mailbox.name"
     />
 </t>
diff --git a/addons/mail/static/src/core/common/discuss_app_category_model.js b/addons/mail/static/src/core/common/discuss_app_category_model.js
new file mode 100644
index 00000000000..28aecc1b0ac
--- /dev/null
+++ b/addons/mail/static/src/core/common/discuss_app_category_model.js
@@ -0,0 +1,41 @@
+/* @odoo-module */
+
+import { assignDefined } from "@mail/utils/common/misc";
+import { Record } from "./record";
+
+export class DiscussAppCategory extends Record {
+    static id = "id";
+    /** @returns {import("models").DiscussAppCategory} */
+    static new(data) {
+        return super.new(data);
+    }
+    /** @returns {import("models").DiscussAppCategory} */
+    static get(data) {
+        return super.get(data);
+    }
+    /** @returns {import("models").DiscussAppCategory} */
+    static insert(data) {
+        const category = this.get(data) ?? this.new(data);
+        assignDefined(category, data);
+        return category;
+    }
+
+    /** @type {string} */
+    extraClass;
+    /** @string */
+    id;
+    /** @type {string} */
+    name;
+    isOpen = false;
+    canView = false;
+    canAdd = false;
+    /** @type {string} */
+    serverStateKey;
+    /** @type {string} */
+    addTitle;
+    /** @type {string} */
+    addHotkey;
+    threads = Record.many("Thread");
+}
+
+DiscussAppCategory.register();
diff --git a/addons/mail/static/src/core/common/discuss_app_model.js b/addons/mail/static/src/core/common/discuss_app_model.js
new file mode 100644
index 00000000000..577ef7c32c1
--- /dev/null
+++ b/addons/mail/static/src/core/common/discuss_app_model.js
@@ -0,0 +1,58 @@
+/* @odoo-module */
+
+import { _t } from "@web/core/l10n/translation";
+import { Record } from "./record";
+
+export class DiscussApp extends Record {
+    /** @returns {import("models").DiscussApp} */
+    static new(data) {
+        const res = super.new(data);
+        Object.assign(res, {
+            channels: this.store.DiscussAppCategory.insert({
+                extraClass: "o-mail-DiscussSidebarCategory-channel",
+                id: "channels",
+                name: _t("Channels"),
+                isOpen: false,
+                canView: true,
+                canAdd: true,
+                serverStateKey: "is_discuss_sidebar_category_channel_open",
+                addTitle: _t("Add or join a channel"),
+                addHotkey: "c",
+            }),
+            chats: this.store.DiscussAppCategory.insert({
+                extraClass: "o-mail-DiscussSidebarCategory-chat",
+                id: "chats",
+                name: _t("Direct messages"),
+                isOpen: false,
+                canView: false,
+                canAdd: true,
+                serverStateKey: "is_discuss_sidebar_category_chat_open",
+                addTitle: _t("Start a conversation"),
+                addHotkey: "d",
+            }),
+        });
+        return res;
+    }
+    /** @returns {import("models").DiscussApp} */
+    static get(data) {
+        return super.get(data);
+    }
+    /** @returns {import("models").DiscussApp} */
+    static insert() {
+        const app = this.get() ?? this.new();
+        return app;
+    }
+
+    /** @type {'mailbox'|'all'|'channel'|'chat'|'livechat'} */
+    activeTab = "all";
+    isActive = false;
+    thread = Record.one("Thread");
+    channels = Record.one("DiscussAppCategory");
+    chats = Record.one("DiscussAppCategory");
+    // mailboxes in sidebar
+    inbox = Record.one("Thread");
+    starred = Record.one("Thread");
+    history = Record.one("Thread");
+}
+
+DiscussApp.register();
diff --git a/addons/mail/static/src/core/common/record.js b/addons/mail/static/src/core/common/record.js
index 0f3497d0375..9bc7a3cf417 100644
--- a/addons/mail/static/src/core/common/record.js
+++ b/addons/mail/static/src/core/common/record.js
@@ -214,6 +214,10 @@ export class RecordList extends Array {
     includes(record) {
         return this.__list__.includes(record.localId);
     }
+    /** @param {(acc: any, r: R) => any} fn */
+    reduce(fn, init) {
+        return this.__list__.reduce((acc, localId) => fn(acc, this.__store__.get(localId)), init);
+    }
     /**
      * @param {number} [start]
      * @param {number} [end]
diff --git a/addons/mail/static/src/core/common/store_service.js b/addons/mail/static/src/core/common/store_service.js
index abb77918a8e..1f544c4701a 100644
--- a/addons/mail/static/src/core/common/store_service.js
+++ b/addons/mail/static/src/core/common/store_service.js
@@ -4,7 +4,6 @@ import { onChange } from "@mail/utils/common/misc";
 
 import { reactive } from "@odoo/owl";
 
-import { _t } from "@web/core/l10n/translation";
 import { registry } from "@web/core/registry";
 import { debounce } from "@web/core/utils/timing";
 import { modelRegistry, Record, RecordInverses, RecordList } from "./record";
@@ -22,6 +21,10 @@ export class Store {
     ChatWindow;
     /** @type {typeof import("@mail/core/common/composer_model").Composer} */
     Composer;
+    /** @type {typeof import("@mail/core/common/discuss_app_model").DiscussApp} */
+    DiscussApp;
+    /** @type {typeof import("@mail/core/common/discuss_app_category_model").DiscussAppCategory} */
+    DiscussAppCategory;
     /** @type {typeof import("@mail/core/common/follower_model").Follower} */
     Follower;
     /** @type {typeof import("@mail/core/common/link_preview_model").LinkPreview} */
@@ -70,7 +73,6 @@ export class Store {
      */
     setup(env) {
         this.env = env;
-        this.discuss.activeTab = this.env.services.ui.isSmall ? "mailbox" : "all";
     }
 
     updateBusSubscription() {
@@ -141,43 +143,7 @@ export class Store {
         counter: 0,
     };
 
-    // discuss app
-    discuss = {
-        activeTab: "all", // can be 'mailbox', 'all', 'channel' or 'chat'
-        isActive: false,
-        threadLocalId: null,
-        channels: {
-            extraClass: "o-mail-DiscussSidebarCategory-channel",
-            id: "channels",
-            name: _t("Channels"),
-            isOpen: false,
-            canView: true,
-            canAdd: true,
-            serverStateKey: "is_discuss_sidebar_category_channel_open",
-            addTitle: _t("Add or join a channel"),
-            addHotkey: "c",
-            threads: [], // list of ids
-        },
-        chats: {
-            extraClass: "o-mail-DiscussSidebarCategory-chat",
-            id: "chats",
-            name: _t("Direct messages"),
-            isOpen: false,
-            canView: false,
-            canAdd: true,
-            serverStateKey: "is_discuss_sidebar_category_chat_open",
-            addTitle: _t("Start a conversation"),
-            addHotkey: "d",
-            threads: [], // list of ids
-        },
-        // mailboxes in sidebar
-        /** @type {import("models").Thread} */
-        inbox: null,
-        /** @type {import("models").Thread} */
-        starred: null,
-        /** @type {import("models").Thread} */
-        history: null,
-    };
+    discuss = Record.one("DiscussApp");
 
     activityCounter = 0;
 
@@ -245,7 +211,7 @@ export const storeService = {
                                 }
                                 return Reflect.get(target, name, receiver);
                             },
-                            deleteProperty(target, key) {
+                            deleteProperty(target, name) {
                                 if (name !== "__rels__" && target.__rels__.has(name)) {
                                     const r1 = target;
                                     const l1 = r1.__rels__.get(name);
@@ -253,8 +219,9 @@ export const storeService = {
                                     if (r2) {
                                         r2.__invs__.delete(r1.localId, name);
                                     }
+                                    r1.__rels__.set(name, undefined);
                                 }
-                                const ret = Reflect.deleteProperty(target, key);
+                                const ret = Reflect.deleteProperty(target, name);
                                 return ret;
                             },
                             /** @param {Record} receiver */
@@ -315,13 +282,14 @@ export const storeService = {
                 Class.__rels__.add(name);
             }
         }
+        res.discuss = res.DiscussApp.insert();
+        res.discuss.activeTab = env.services.ui.isSmall ? "mailbox" : "all";
         onChange(res.Thread, "records", () => res.updateBusSubscription());
         services.ui.bus.addEventListener("resize", () => {
             if (!services.ui.isSmall) {
                 res.discuss.activeTab = "all";
             } else {
-                res.discuss.activeTab =
-                    res.Thread.records[res.discuss.threadLocalId]?.type ?? "all";
+                res.discuss.activeTab = res.discuss.thread?.type ?? "all";
             }
         });
         return res;
diff --git a/addons/mail/static/src/core/common/thread_model.js b/addons/mail/static/src/core/common/thread_model.js
index bb83be4b9cf..d06c7a4aaa6 100644
--- a/addons/mail/static/src/core/common/thread_model.js
+++ b/addons/mail/static/src/core/common/thread_model.js
@@ -75,8 +75,8 @@ export class Thread extends Record {
         onChange(thread, "isLoaded", () => thread.isLoadedDeferred.resolve());
         onChange(thread, "channelMembers", () => this.store.updateBusSubscription());
         onChange(thread, "is_pinned", () => {
-            if (!thread.is_pinned && this.store.discuss.threadLocalId === thread.localId) {
-                this.store.discuss.threadLocalId = null;
+            if (!thread.is_pinned && thread.eq(this.store.discuss.thread)) {
+                delete this.store.discuss.thread;
             }
         });
         thread.update(data);
@@ -199,16 +199,13 @@ export class Thread extends Record {
                 );
             }
         }
-        if (
-            this.type === "channel" &&
-            !this._store.discuss.channels.threads.includes(this.localId)
-        ) {
-            this._store.discuss.channels.threads.push(this.localId);
+        if (this.type === "channel" && !this._store.discuss.channels.threads.includes(this)) {
+            this._store.discuss.channels.threads.push(this);
         } else if (
             (this.type === "chat" || this.type === "group") &&
-            !this._store.discuss.chats.threads.includes(this.localId)
+            !this._store.discuss.chats.threads.includes(this)
         ) {
-            this._store.discuss.chats.threads.push(this.localId);
+            this._store.discuss.chats.threads.push(this);
         }
         if (!this.type && !["mail.box", "discuss.channel"].includes(this.model)) {
             this.type = "chatter";
diff --git a/addons/mail/static/src/core/common/thread_service.js b/addons/mail/static/src/core/common/thread_service.js
index 8bd093170ba..5a01544cfb2 100644
--- a/addons/mail/static/src/core/common/thread_service.js
+++ b/addons/mail/static/src/core/common/thread_service.js
@@ -2,7 +2,6 @@
 
 import { loadEmoji } from "@web/core/emoji_picker/emoji_picker";
 import { DEFAULT_AVATAR } from "@mail/core/common/persona_service";
-import { removeFromArray } from "@mail/utils/common/arrays";
 import { prettifyMessageContent } from "@mail/utils/common/format";
 
 import { markup } from "@odoo/owl";
@@ -413,7 +412,7 @@ export class ThreadService {
     }
 
     unpin(thread) {
-        if (this.store.discuss.threadLocalId === thread.localId) {
+        if (thread.eq(this.store.discuss.thread)) {
             this.router.replaceState({ active_id: undefined });
         }
         if (thread.model !== "discuss.channel") {
@@ -435,16 +434,12 @@ export class ThreadService {
     }
 
     sortChannels() {
-        this.store.discuss.channels.threads.sort((id1, id2) => {
-            const thread1 = this.store.Thread.records[id1];
-            const thread2 = this.store.Thread.records[id2];
-            return String.prototype.localeCompare.call(thread1.name, thread2.name);
-        });
-        this.store.discuss.chats.threads.sort((localId_1, localId_2) => {
-            const thread1 = this.store.Thread.records[localId_1];
-            const thread2 = this.store.Thread.records[localId_2];
-            return thread2.lastInterestDateTime.ts - thread1.lastInterestDateTime.ts;
-        });
+        this.store.discuss.channels.threads.sort((t1, t2) =>
+            String.prototype.localeCompare.call(t1.name, t2.name)
+        );
+        this.store.discuss.chats.threads.sort(
+            (t1, t2) => t2.lastInterestDateTime.ts - t1.lastInterestDateTime.ts
+        );
     }
 
     /**
@@ -626,10 +621,10 @@ export class ThreadService {
 
     async leaveChannel(channel) {
         await this.orm.call("discuss.channel", "action_unfollow", [channel.id]);
-        this.remove(channel);
+        channel.delete();
         this.setDiscussThread(
             this.store.discuss.channels.threads[0]
-                ? this.store.Thread.records[this.store.discuss.channels.threads[0]]
+                ? this.store.discuss.channels.threads[0]
                 : this.store.discuss.inbox
         );
     }
@@ -639,7 +634,7 @@ export class ThreadService {
      * @param {boolean} pushState
      */
     setDiscussThread(thread, pushState = true) {
-        this.store.discuss.threadLocalId = thread.localId;
+        this.store.discuss.thread = thread;
         const activeId =
             typeof thread.id === "string"
                 ? `mail.box_${thread.id}`
@@ -656,12 +651,6 @@ export class ThreadService {
         }
     }
 
-    remove(thread) {
-        removeFromArray(this.store.discuss.chats.threads, thread.localId);
-        removeFromArray(this.store.discuss.channels.threads, thread.localId);
-        thread.delete();
-    }
-
     /**
      * @param {import("models").Thread} thread
      * @param {string} body
@@ -835,8 +824,7 @@ export class ThreadService {
     }
 
     getDiscussSidebarCategoryCounter(categoryId) {
-        return this.store.discuss[categoryId].threads.reduce((acc, threadLocalId) => {
-            const channel = this.store.Thread.records[threadLocalId];
+        return this.store.discuss[categoryId].threads.reduce((acc, channel) => {
             if (categoryId === "channels") {
                 return channel.message_needaction_counter > 0 ? acc + 1 : acc;
             } else {
diff --git a/addons/mail/static/src/core/web/discuss_client_action.js b/addons/mail/static/src/core/web/discuss_client_action.js
index c2ab5cfc51d..b4263ac1c49 100644
--- a/addons/mail/static/src/core/web/discuss_client_action.js
+++ b/addons/mail/static/src/core/web/discuss_client_action.js
@@ -44,7 +44,7 @@ export class DiscussClientAction extends Component {
         const rawActiveId =
             props.action.context.active_id ??
             props.action.params?.active_id ??
-            this.store.Thread.localIdToActiveId(this.store.discuss.threadLocalId) ??
+            this.store.Thread.localIdToActiveId(this.store.discuss.thread?.localId) ??
             "mail.box_inbox";
         const activeId =
             typeof rawActiveId === "number" ? `discuss.channel_${rawActiveId}` : rawActiveId;
@@ -53,8 +53,8 @@ export class DiscussClientAction extends Component {
             // legacy format (sent in old emails, shared links, ...)
             model = "discuss.channel";
         }
-        const activeThreadLocalId = this.store.Thread.localId({ model, id });
-        if (activeThreadLocalId !== this.store.discuss.threadLocalId) {
+        const activeThread = this.store.Thread.get({ model, id });
+        if (!activeThread || activeThread.notEq(this.store.discuss.thread)) {
             const thread =
                 this.store.Thread.get({ model, id }) ??
                 (await this.threadService.fetchChannel(parseInt(id)));
diff --git a/addons/mail/static/src/core/web/discuss_sidebar_mailboxes.xml b/addons/mail/static/src/core/web/discuss_sidebar_mailboxes.xml
index 08251db13f4..c7b72ea1b51 100644
--- a/addons/mail/static/src/core/web/discuss_sidebar_mailboxes.xml
+++ b/addons/mail/static/src/core/web/discuss_sidebar_mailboxes.xml
@@ -19,8 +19,8 @@
         <button
             class="o-mail-DiscussSidebar-item btn d-flex align-items-center py-1 px-0 border-0 rounded-0 fw-normal text-reset"
             t-att-class="{
-                'o-bg-inherit': mailbox.localId !== store.discuss.threadLocalId,
-                'o-active': mailbox.localId === store.discuss.threadLocalId,
+                'o-bg-inherit': mailbox.notEq(store.discuss.thread),
+                'o-active': mailbox.eq(store.discuss.thread),
             }"
             t-on-click="(ev) => this.openThread(ev, mailbox)"
         >
diff --git a/addons/mail/static/src/core/web/messaging_menu.js b/addons/mail/static/src/core/web/messaging_menu.js
index 30cfe87acce..c39d8999707 100644
--- a/addons/mail/static/src/core/web/messaging_menu.js
+++ b/addons/mail/static/src/core/web/messaging_menu.js
@@ -279,15 +279,14 @@ export class MessagingMenu extends Component {
         this.store.discuss.activeTab = tabId;
         if (
             this.store.discuss.activeTab === "mailbox" &&
-            (!this.store.discuss.threadLocalId ||
-                this.store.Thread.records[this.store.discuss.threadLocalId].type !== "mailbox")
+            (!this.store.discuss.thread || this.store.discuss.thread.type !== "mailbox")
         ) {
             this.threadService.setDiscussThread(
                 Object.values(this.store.Thread.records).find((thread) => thread.id === "inbox")
             );
         }
         if (this.store.discuss.activeTab !== "mailbox") {
-            this.store.discuss.threadLocalId = null;
+            delete this.store.discuss.thread;
         }
     }
 
diff --git a/addons/mail/static/src/discuss/core/common/discuss_core_common_service.js b/addons/mail/static/src/discuss/core/common/discuss_core_common_service.js
index e45f550ffb0..2884557abdd 100644
--- a/addons/mail/static/src/discuss/core/common/discuss_core_common_service.js
+++ b/addons/mail/static/src/discuss/core/common/discuss_core_common_service.js
@@ -60,13 +60,10 @@ export class DiscussCoreCommon {
                     ...payload,
                     model: "discuss.channel",
                 });
-                this.threadService.remove(thread);
-                if (thread.localId === this.store.discuss.threadLocalId) {
-                    this.store.discuss.threadLocalId = undefined;
-                }
                 this.notificationService.add(_t("You unsubscribed from %s.", thread.displayName), {
                     type: "info",
                 });
+                thread.delete();
             });
             this.busService.subscribe("discuss.channel/legacy_insert", (payload) => {
                 this.store.Thread.insert({
diff --git a/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.js b/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.js
index 1540da38609..bfd1393987d 100644
--- a/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.js
+++ b/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.js
@@ -81,8 +81,7 @@ export class DiscussSidebarCategories extends Component {
     }
 
     filteredThreads(category) {
-        return category.threads.filter((threadLocalId) => {
-            const thread = this.store.Thread.records[threadLocalId];
+        return category.threads.filter((thread) => {
             return (
                 (thread.is_pinned || thread.group_based_subscription) &&
                 (!this.state.quickSearchVal ||
diff --git a/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml b/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml
index 91f9ba6e49d..1c9871d092e 100644
--- a/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml
+++ b/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml
@@ -30,13 +30,12 @@
             <div t-if="state.editing === category.id" class="p-2" t-ref="selector">
                 <ChannelSelector category="category" onValidate.bind="stopEditing" autofocus="true"/>
             </div>
-            <t t-foreach="filteredThreads(category)" t-as="threadLocalId" t-key="threadLocalId" t-call="mail.DiscussSidebarChannel">
-                <t t-set="thread" t-value="store.Thread.records[threadLocalId]"/>
+            <t t-foreach="filteredThreads(category)" t-as="thread" t-key="thread.localId" t-call="mail.DiscussSidebarChannel">
+                <t t-set="thread" t-value="thread"/>
             </t>
         </t>
-        <t t-elif="category.threads.includes(store.discuss.threadLocalId)" t-call="mail.DiscussSidebarChannel">
-            <t t-set="threadLocalId" t-value="store.discuss.threadLocalId"/>
-            <t t-set="thread" t-value="store.Thread.records[threadLocalId]"/>
+        <t t-elif="category.threads.includes(store.discuss.thread)" t-call="mail.DiscussSidebarChannel">
+            <t t-set="thread" t-value="store.discuss.thread"/>
         </t>
     </t>
 
@@ -44,8 +43,8 @@
         <t t-set="counter" t-value="threadService.getCounter(thread)"/>
         <button class="o-mail-DiscussSidebarChannel o-mail-DiscussSidebar-item btn btn-secondary d-flex align-items-center w-100 px-0 py-2 border-0 rounded-0 text-reset"
             t-att-class="{
-                'o-bg-inherit': threadLocalId !== store.discuss.threadLocalId,
-                'o-active': threadLocalId === store.discuss.threadLocalId,
+                'o-bg-inherit': thread.notEq(store.discuss.thread),
+                'o-active': thread.eq(store.discuss.thread),
                 'o-unread': thread.message_unread_counter > 0,
             }"
             t-on-click="(ev) => this.openThread(ev, thread)"