diff --git a/addons/mail/static/src/discuss/core/web/discuss_core_web_service.js b/addons/mail/static/src/discuss/core/web/discuss_core_web_service.js
index 49ce17950be..db922f4d50b 100644
--- a/addons/mail/static/src/discuss/core/web/discuss_core_web_service.js
+++ b/addons/mail/static/src/discuss/core/web/discuss_core_web_service.js
@@ -1,5 +1,6 @@
 /* @odoo-module */
 
+import { createLocalId } from "@mail/utils/common/misc";
 import { reactive } from "@odoo/owl";
 
 import { _t } from "@web/core/l10n/translation";
@@ -73,6 +74,28 @@ export class DiscussCoreWeb {
                 this.chatWindowService.insert({ thread: chat });
             }
         });
+        this.busService.subscribe("mail.record/insert", async (payload) => {
+            if (payload.Thread) {
+                const data = payload.Thread;
+                const thread = this.store.threads[createLocalId(data.model, data.id)];
+                if (data.serverFoldState && thread && data.serverFoldState !== thread.state) {
+                    thread.state = data.serverFoldState;
+                    if (thread.state === "closed") {
+                        const chatWindow = this.store.chatWindows.find(
+                            (chatWindow) => chatWindow.threadLocalId === thread.localId
+                        );
+                        if (chatWindow) {
+                            this.chatWindowService.close(chatWindow);
+                        }
+                    } else {
+                        this.chatWindowService.insert({
+                            thread,
+                            folded: thread.state === "folded",
+                        });
+                    }
+                }
+            }
+        });
     }
 }
 
diff --git a/addons/mail/static/tests/chat_window/chat_window_tests.js b/addons/mail/static/tests/chat_window/chat_window_tests.js
index 936998bf1d0..ba5160564a2 100644
--- a/addons/mail/static/tests/chat_window/chat_window_tests.js
+++ b/addons/mail/static/tests/chat_window/chat_window_tests.js
@@ -161,6 +161,24 @@ QUnit.test("chat window: basic rendering", async (assert) => {
     assert.containsOnce($, "[title='Open in Discuss']");
 });
 
+QUnit.test("Fold state of chat window is sync among browser tabs", async (assert) => {
+    const pyEnv = await startServer();
+    pyEnv["discuss.channel"].create({ name: "General" });
+    const tab1 = await start({ asTab: true });
+    const tab2 = await start({ asTab: true });
+    await tab1.click(".o_menu_systray i[aria-label='Messages']");
+    await tab1.click(".o-mail-NotificationItem");
+    await tab1.click(".o-mail-ChatWindow-header"); // Fold
+    assert.containsNone(tab1.target, ".o-mail-ChatWindow .o-mail-ChatWindow-content");
+    assert.containsNone(tab2.target, ".o-mail-ChatWindow .o-mail-ChatWindow-content");
+    await tab2.click(".o-mail-ChatWindow-header"); // Unfold
+    assert.containsOnce(tab1.target, ".o-mail-ChatWindow .o-mail-ChatWindow-content");
+    assert.containsOnce(tab2.target, ".o-mail-ChatWindow .o-mail-ChatWindow-content");
+    await tab1.click("[title='Close Chat Window']");
+    assert.containsNone(tab1.target, ".o-mail-ChatWindow");
+    assert.containsNone(tab2.target, ".o-mail-ChatWindow");
+});
+
 QUnit.test(
     "Mobile: opening a chat window should not update channel state on the server",
     async (assert) => {