fix: prevent duplicate livechat rooms on concurrent requests (RocketChat#39087)

Author: ricardogarim

.changeset/fluffy-turtles-admire.md

@@ -0,0 +1,6 @@
+---
+'@rocket.chat/models': patch
+'@rocket.chat/meteor': patch
+---
+
+Fixes race condition causing duplicate open livechat rooms per visitor token.

apps/meteor/app/livechat/server/lib/Helper.ts

@@ -145,6 +145,9 @@ export const prepareLivechatRoom = async (
 		priorityWeight: LivechatPriorityWeight.NOT_SPECIFIED,
 		estimatedWaitingTimeQueue: DEFAULT_SLA_CONFIG.ESTIMATED_WAITING_TIME_QUEUE,
 		...extraRoomInfo,
+		// marker field for unique index - only new rooms have this field (see #39087)
+		// allows index creation to succeed even if old duplicates exist
+		_enforceSingleRoom: true,
 	} as InsertionModel<IOmnichannelRoom>;
 };
 

packages/models/src/models/LivechatRooms.ts

@@ -77,6 +77,15 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 			{ key: { servedBy: 1, ts: 1 }, partialFilterExpression: { servedBy: { $exists: true }, t: 'l' } },
 			{ key: { 'v.activity': 1, 'ts': 1 }, partialFilterExpression: { 'v.activity': { $exists: true }, 't': 'l' } },
 			{ key: { contactId: 1 }, partialFilterExpression: { contactId: { $exists: true }, t: 'l' } },
+			{
+				key: { 'v.token': 1 },
+				unique: true,
+				partialFilterExpression: {
+					t: 'l',
+					open: true,
+					_enforceSingleRoom: true,
+				},
+			},
 		];
 	}