[FIX] im_livechat: keep same livechat name after inviting members

Before this commit, inviting a channel member to a livechat channel
would change its name. This is not what we want as the thread name
should always be the one of the visitor (e.g. "Visitor 20", task-3332872).

Steps to reproduce:
- Open two tabs, one with admin log, one on the support page
- Click on the livechat button and send a message from the support page
- Invite a member with the admin tab
- The name of the thread changed.

closes odoo/odoo#128238

Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/im_livechat/static/src/core/thread_model_patch.js

@@ -34,6 +34,22 @@ patch(Thread.prototype, "im_livechat", {
         return this._super().filter((correspondent) => !correspondent.is_bot);
     },
 
+    get correspondent() {
+        let correspondent = this._super();
+        if (this.type === "livechat" && !correspondent) {
+            // For livechat threads, the correspondent is the first
+            // channel member that is not the operator.
+            const orderedChannelMembers = [...this.channelMembers].sort((a, b) => a.id - b.id);
+            const isFirstMemberOperator =
+                orderedChannelMembers[0]?.persona.type === "partner" &&
+                orderedChannelMembers[0]?.persona.id === this.operator.id;
+            correspondent = isFirstMemberOperator
+                ? orderedChannelMembers[1]?.persona
+                : orderedChannelMembers[0]?.persona;
+        }
+        return correspondent;
+    },
+
     get displayName() {
         if (this.type !== "livechat" || !this.correspondent) {
             return this._super();

addons/im_livechat/static/src/core/thread_service_patch.js

@@ -14,6 +14,13 @@ patch(ThreadService.prototype, "im_livechat", {
             if (data?.channel) {
                 assignDefined(thread, data.channel, ["anonymous_name"]);
             }
+            if (data?.operator_pid) {
+                thread.operator = this.personaService.insert({
+                    type: "partner",
+                    id: data.operator_pid[0],
+                    displayName: data.operator_pid[1],
+                });
+            }
             if (isUnknown) {
                 this.store.discuss.livechat.threads.push(thread.localId);
                 this.sortChannels();

addons/im_livechat/static/tests/thread_model_patch_tests.js

@@ -0,0 +1,35 @@
+/* @odoo-module */
+
+import { startServer } from "@bus/../tests/helpers/mock_python_environment";
+
+import { Command } from "@mail/../tests/helpers/command";
+import { click, start } from "@mail/../tests/helpers/test_utils";
+
+QUnit.module("Thread model");
+
+QUnit.test("Thread name unchanged when inviting new users", async (assert) => {
+    const pyEnv = await startServer();
+    const userId = pyEnv["res.users"].create({ name: "James" });
+    pyEnv["res.partner"].create({
+        name: "James",
+        user_ids: [userId],
+    });
+    const channelId = pyEnv["discuss.channel"].create({
+        anonymous_name: "Visitor #20",
+        channel_member_ids: [
+            Command.create({ partner_id: pyEnv.currentPartnerId }),
+            Command.create({ partner_id: pyEnv.publicPartnerId }),
+        ],
+        channel_type: "livechat",
+        livechat_operator_id: pyEnv.currentPartnerId,
+    });
+    const { openDiscuss } = await start();
+    await openDiscuss(channelId);
+    assert.containsOnce($, ".o-mail-Discuss-threadName[title='Visitor #20']");
+    await click("button[title='Add Users']");
+    await click(".o-discuss-ChannelInvitation-selectable:contains(James) input");
+    await click("button:contains(Invite)");
+    await click("button[title='Show Member List']");
+    assert.containsOnce($, ".o-discuss-ChannelMember:contains(James)");
+    assert.containsOnce($, ".o-mail-Discuss-threadName[title='Visitor #20']");
+});