diff --git a/.github/workflows/ci-test-e2e.yml b/.github/workflows/ci-test-e2e.yml
index 99395082a9fbc..62ea2af7368f7 100644
--- a/.github/workflows/ci-test-e2e.yml
+++ b/.github/workflows/ci-test-e2e.yml
@@ -57,6 +57,14 @@ on:
         required: false
       CODECOV_TOKEN:
         required: false
+      CI_MONGO_URL:
+        required: false
+      NETBIRD_SETUP_KEY:
+        required: false
+      NETBIRD_PSK:
+        required: false
+      NETBIRD_TEST_IP:
+        required: false
       REPORTER_JIRA_ROCKETCHAT_API_KEY:
         required: false
 
@@ -71,10 +79,12 @@ jobs:
     runs-on: ubuntu-24.04
 
     env:
+      # secrets are not available in step `if:`; use for steps that must run only with CI_MONGO_URL
+      HAS_CI_MONGO_URL: ${{ secrets.CI_MONGO_URL != '' && 'true' || 'false' }}
       # if building for production on develop branch or release, add suffix for coverage images
       DOCKER_TAG_SUFFIX_ROCKETCHAT: ${{ inputs.coverage == matrix.mongodb-version && (github.event_name == 'release' || github.ref == 'refs/heads/develop') && '-cov' || '' }}
       MONGODB_VERSION: ${{ matrix.mongodb-version }}
-      COVERAGE_DIR: '/tmp/coverage/${{ startsWith(inputs.type, ''api'') && ''api'' || inputs.type }}'
+      COVERAGE_DIR: "/tmp/coverage/${{ startsWith(inputs.type, 'api') && 'api' || inputs.type }}"
       COVERAGE_FILE_NAME: '${{ inputs.type }}-${{ matrix.shard }}.json'
       COVERAGE_REPORTER: ${{ inputs.coverage == matrix.mongodb-version && 'json' || '' }}
 
@@ -155,6 +165,29 @@ jobs:
           # List loaded images
           docker images
 
+      - name: Connect to NetBird
+        if: env.HAS_CI_MONGO_URL == 'true'
+        uses: RocketChat/netbird-connect@main
+        with:
+          setup-key: ${{ secrets.NETBIRD_SETUP_KEY }}
+          preshared-key: ${{ secrets.NETBIRD_PSK }}
+          test-ip: ${{ secrets.NETBIRD_TEST_IP }}
+
+      - name: Configure external MongoDB URL
+        env:
+          CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+        if: env.CI_MONGO_URL != ''
+        run: |
+          DB_NAME="rocketchat_${{ inputs.type }}_${{ matrix.shard }}_${{ github.run_id }}_${{ github.run_attempt }}"
+          BASE="${CI_MONGO_URL%%\?*}"
+          BASE="${BASE%/}"
+          QUERY="${CI_MONGO_URL#"$BASE"}"
+          FULL_URL="${BASE}/${DB_NAME}${QUERY}"
+          echo "MONGO_URL=${FULL_URL}" >> $GITHUB_ENV
+          echo "DOCKER_MONGO_URL=${FULL_URL}" >> $GITHUB_ENV
+          echo "EXTERNAL_MONGO=true" >> $GITHUB_ENV
+          echo "DOCUMENTDB=true" >> $GITHUB_ENV
+
       - name: Set DEBUG_LOG_LEVEL (debug enabled)
         if: runner.debug == '1'
         run: echo "DEBUG_LOG_LEVEL=2" >> $GITHUB_ENV
@@ -175,7 +208,11 @@ jobs:
         if: inputs.release == 'ce'
         run: |
           # when we are testing CE, we only need to start the rocketchat container
-          DEBUG_LOG_LEVEL=${DEBUG_LOG_LEVEL:-0} docker compose -f docker-compose-ci.yml up -d rocketchat --wait
+          EXTRA_ARGS=""
+          if [ "$EXTERNAL_MONGO" = "true" ]; then
+            EXTRA_ARGS="--scale mongo=0"
+          fi
+          DEBUG_LOG_LEVEL=${DEBUG_LOG_LEVEL:-0} docker compose -f docker-compose-ci.yml up -d rocketchat $EXTRA_ARGS --wait
 
       - name: Start containers for EE
         if: inputs.release == 'ee'
@@ -183,7 +220,11 @@ jobs:
           ENTERPRISE_LICENSE: ${{ inputs.enterprise-license }}
           TRANSPORTER: ${{ inputs.transporter }}
         run: |
-          DEBUG_LOG_LEVEL=${DEBUG_LOG_LEVEL:-0} docker compose -f docker-compose-ci.yml up -d --wait
+          EXTRA_ARGS=""
+          if [ "$EXTERNAL_MONGO" = "true" ]; then
+            EXTRA_ARGS="--scale mongo=0"
+          fi
+          DEBUG_LOG_LEVEL=${DEBUG_LOG_LEVEL:-0} docker compose -f docker-compose-ci.yml up -d $EXTRA_ARGS --wait
 
       - uses: ./.github/actions/setup-playwright
         if: inputs.type == 'ui'
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d590223204a86..bdd84f845dfad 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -500,6 +500,10 @@ jobs:
     secrets:
       CR_USER: ${{ secrets.CR_USER }}
       CR_PAT: ${{ secrets.CR_PAT }}
+      CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+      NETBIRD_SETUP_KEY: ${{ secrets.NETBIRD_SETUP_KEY }}
+      NETBIRD_PSK: ${{ secrets.NETBIRD_PSK }}
+      NETBIRD_TEST_IP: ${{ secrets.NETBIRD_TEST_IP }}
 
   test-api-livechat:
     name: 🔨 Test API Livechat (CE)
@@ -516,6 +520,10 @@ jobs:
     secrets:
       CR_USER: ${{ secrets.CR_USER }}
       CR_PAT: ${{ secrets.CR_PAT }}
+      CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+      NETBIRD_SETUP_KEY: ${{ secrets.NETBIRD_SETUP_KEY }}
+      NETBIRD_PSK: ${{ secrets.NETBIRD_PSK }}
+      NETBIRD_TEST_IP: ${{ secrets.NETBIRD_TEST_IP }}
 
   test-ui:
     name: 🔨 Test UI (CE)
@@ -541,6 +549,10 @@ jobs:
       REPORTER_ROCKETCHAT_API_KEY: ${{ secrets.REPORTER_ROCKETCHAT_API_KEY }}
       REPORTER_ROCKETCHAT_URL: ${{ secrets.REPORTER_ROCKETCHAT_URL }}
       REPORTER_JIRA_ROCKETCHAT_API_KEY: ${{ secrets.REPORTER_JIRA_ROCKETCHAT_API_KEY }}
+      CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+      NETBIRD_SETUP_KEY: ${{ secrets.NETBIRD_SETUP_KEY }}
+      NETBIRD_PSK: ${{ secrets.NETBIRD_PSK }}
+      NETBIRD_TEST_IP: ${{ secrets.NETBIRD_TEST_IP }}
 
   test-api-ee:
     name: 🔨 Test API (EE)
@@ -561,6 +573,10 @@ jobs:
     secrets:
       CR_USER: ${{ secrets.CR_USER }}
       CR_PAT: ${{ secrets.CR_PAT }}
+      CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+      NETBIRD_SETUP_KEY: ${{ secrets.NETBIRD_SETUP_KEY }}
+      NETBIRD_PSK: ${{ secrets.NETBIRD_PSK }}
+      NETBIRD_TEST_IP: ${{ secrets.NETBIRD_TEST_IP }}
 
   test-api-livechat-ee:
     name: 🔨 Test API Livechat (EE)
@@ -581,6 +597,10 @@ jobs:
     secrets:
       CR_USER: ${{ secrets.CR_USER }}
       CR_PAT: ${{ secrets.CR_PAT }}
+      CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+      NETBIRD_SETUP_KEY: ${{ secrets.NETBIRD_SETUP_KEY }}
+      NETBIRD_PSK: ${{ secrets.NETBIRD_PSK }}
+      NETBIRD_TEST_IP: ${{ secrets.NETBIRD_TEST_IP }}
 
   test-ui-ee:
     name: 🔨 Test UI (EE)
@@ -609,6 +629,10 @@ jobs:
       REPORTER_ROCKETCHAT_URL: ${{ secrets.REPORTER_ROCKETCHAT_URL }}
       CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
       REPORTER_JIRA_ROCKETCHAT_API_KEY: ${{ secrets.REPORTER_JIRA_ROCKETCHAT_API_KEY }}
+      CI_MONGO_URL: ${{ secrets.CI_MONGO_URL }}
+      NETBIRD_SETUP_KEY: ${{ secrets.NETBIRD_SETUP_KEY }}
+      NETBIRD_PSK: ${{ secrets.NETBIRD_PSK }}
+      NETBIRD_TEST_IP: ${{ secrets.NETBIRD_TEST_IP }}
 
   test-federation-matrix:
     name: 🔨 Test Federation Matrix
diff --git a/apps/meteor/app/api/server/lib/users.ts b/apps/meteor/app/api/server/lib/users.ts
index 00dfc3e8f5292..c11955f3da0ef 100644
--- a/apps/meteor/app/api/server/lib/users.ts
+++ b/apps/meteor/app/api/server/lib/users.ts
@@ -1,5 +1,5 @@
 import type { IUser } from '@rocket.chat/core-typings';
-import { Users, Subscriptions } from '@rocket.chat/models';
+import { Users, Subscriptions, getAllowDiskUse } from '@rocket.chat/models';
 import { escapeRegExp } from '@rocket.chat/string-helpers';
 import type { Mongo } from 'meteor/mongo';
 import type { Filter, FindOptions, RootFilterOperators } from 'mongodb';
@@ -229,7 +229,7 @@ export async function findPaginatedUsersByStatus({
 			skip: offset,
 			limit: count,
 			projection,
-			allowDiskUse: true,
+			...getAllowDiskUse(),
 		},
 	);
 	const [users, total] = await Promise.all([cursor.toArray(), totalCount]);
diff --git a/apps/meteor/app/api/server/v1/users.ts b/apps/meteor/app/api/server/v1/users.ts
index 50c65abcd8d12..6181770b315b3 100644
--- a/apps/meteor/app/api/server/v1/users.ts
+++ b/apps/meteor/app/api/server/v1/users.ts
@@ -543,42 +543,28 @@ API.v1.addRoute(
 						]
 					: [];
 
-			const result = await Users.col
-				.aggregate<{ sortedResults: IUser[]; totalCount: { total: number }[] }>([
-					{
-						$match: nonEmptyQuery,
-					},
-					{
-						$project: inclusiveFields,
-					},
-					{
-						$addFields: {
-							nameInsensitive: {
-								$toLower: '$name',
-							},
-						},
-					},
-					{
-						$facet: {
-							sortedResults: [
-								{
-									$sort: actualSort,
-								},
-								{
-									$skip: offset,
-								},
-								...limit,
-							],
-							totalCount: [{ $group: { _id: null, total: { $sum: 1 } } }],
+			const baseQuery = [
+				{
+					$match: nonEmptyQuery,
+				},
+				{
+					$project: inclusiveFields,
+				},
+				{
+					$addFields: {
+						nameInsensitive: {
+							$toLower: '$name',
 						},
 					},
-				])
-				.toArray();
+				},
+			];
+
+			const [users, countResult] = await Promise.all([
+				Users.col.aggregate<IUser>([...baseQuery, { $sort: actualSort }, { $skip: offset }, ...limit]).toArray(),
+				Users.col.aggregate<{ total: number }>([...baseQuery, { $count: 'total' }]).toArray(),
+			]);
 
-			const {
-				sortedResults: users,
-				totalCount: [{ total } = { total: 0 }],
-			} = result[0];
+			const total = countResult[0]?.total || 0;
 
 			return API.v1.success({
 				users,
diff --git a/apps/meteor/app/livechat/server/lib/QueueManager.ts b/apps/meteor/app/livechat/server/lib/QueueManager.ts
index c012a8a7d8a0b..784a1bdb1725f 100644
--- a/apps/meteor/app/livechat/server/lib/QueueManager.ts
+++ b/apps/meteor/app/livechat/server/lib/QueueManager.ts
@@ -27,7 +27,7 @@ import { afterInquiryQueued, afterRoomQueued, beforeDelegateAgent, beforeRouteCh
 import { checkOnlineAgents, getOnlineAgents } from './service-status';
 import { getInquirySortMechanismSetting } from './settings';
 import { dispatchInquiryPosition } from '../../../../ee/app/livechat-enterprise/server/lib/Helper';
-import { client, shouldRetryTransaction } from '../../../../server/database/utils';
+import { client, shouldRetryTransaction, transactionOptions } from '../../../../server/database/utils';
 import { sendNotification } from '../../../lib/server';
 import { notifyOnLivechatInquiryChangedById, notifyOnLivechatInquiryChanged } from '../../../lib/server/lib/notifyListener';
 import { settings } from '../../../settings/server';
@@ -257,7 +257,7 @@ export class QueueManager {
 	): Promise<{ room: IOmnichannelRoom; inquiry: ILivechatInquiryRecord }> {
 		const session = client.startSession();
 		try {
-			session.startTransaction();
+			session.startTransaction(transactionOptions);
 			const room = await createLivechatRoom(insertionRoom, session);
 			logger.debug({ msg: 'Room created for visitor', visitorId: guest._id, roomId: room._id });
 			const inquiry = await createLivechatInquiry({
diff --git a/apps/meteor/app/livechat/server/lib/closeRoom.ts b/apps/meteor/app/livechat/server/lib/closeRoom.ts
index 8ee99231ee609..f5c036e8062de 100644
--- a/apps/meteor/app/livechat/server/lib/closeRoom.ts
+++ b/apps/meteor/app/livechat/server/lib/closeRoom.ts
@@ -9,7 +9,7 @@ import type { ClientSession } from 'mongodb';
 import type { CloseRoomParams, CloseRoomParamsByUser, CloseRoomParamsByVisitor } from './localTypes';
 import { livechatLogger as logger } from './logger';
 import { parseTranscriptRequest } from './parseTranscriptRequest';
-import { client, shouldRetryTransaction } from '../../../../server/database/utils';
+import { client, shouldRetryTransaction, transactionOptions } from '../../../../server/database/utils';
 import { callbacks } from '../../../../server/lib/callbacks';
 import {
 	notifyOnLivechatInquiryChanged,
@@ -33,7 +33,7 @@ export async function closeRoom(params: CloseRoomParams, attempts = 2): Promise<
 
 	const session = client.startSession();
 	try {
-		session.startTransaction();
+		session.startTransaction(transactionOptions);
 		const { room, closedBy, removedInquiry } = await doCloseRoom(params, session);
 		await session.commitTransaction();
 
diff --git a/apps/meteor/app/settings/server/SettingsRegistry.ts b/apps/meteor/app/settings/server/SettingsRegistry.ts
index 3b93ca5c0bfb6..55eabd4f52b69 100644
--- a/apps/meteor/app/settings/server/SettingsRegistry.ts
+++ b/apps/meteor/app/settings/server/SettingsRegistry.ts
@@ -198,7 +198,17 @@ export class SettingsRegistry {
 
 		const setting = isOverwritten ? settingFromCodeOverwritten : settingOverwrittenDefault;
 
-		await this.model.insertOne(setting); // no need to emit unless we remove the oplog
+		try {
+			await this.model.insertOne(setting); // no need to emit unless we remove the oplog
+		} catch (e: any) {
+			// Another process inserted the same setting first (e.g. main app + EE
+			// microservices booting in parallel). The check above is in-memory and
+			// not atomic, so concurrent boots race on the unique _id index.
+			// E11000 here is safe to ignore — the setting now exists.
+			if (e?.code !== 11000) {
+				throw e;
+			}
+		}
 
 		this.store.set(setting);
 	}
@@ -224,7 +234,16 @@ export class SettingsRegistry {
 		if (!this.store.has(_id)) {
 			options.ts = new Date();
 			this.store.set(options as ISetting);
-			await this.model.insertOne(options as ISetting);
+			try {
+				await this.model.insertOne(options as ISetting);
+			} catch (e: any) {
+				// Race with another process (main app + EE microservices boot in
+				// parallel). Same rationale as in `add` above — E11000 here means
+				// another caller wrote the group first; the desired state holds.
+				if (e?.code !== 11000) {
+					throw e;
+				}
+			}
 		}
 
 		if (!callback) {
diff --git a/apps/meteor/ee/server/api/abac/index.ts b/apps/meteor/ee/server/api/abac/index.ts
index 0ed503678f527..8cce4c8a4ae78 100644
--- a/apps/meteor/ee/server/api/abac/index.ts
+++ b/apps/meteor/ee/server/api/abac/index.ts
@@ -1,7 +1,7 @@
 import { Abac } from '@rocket.chat/core-services';
 import type { AbacActor } from '@rocket.chat/core-services';
 import type { IServerEvents, IUser } from '@rocket.chat/core-typings';
-import { ServerEvents, Users } from '@rocket.chat/models';
+import { ServerEvents, Users, getAllowDiskUse } from '@rocket.chat/models';
 import { validateUnauthorizedErrorResponse } from '@rocket.chat/rest-typings/src/v1/Ajv';
 import { convertSubObjectsIntoPaths } from '@rocket.chat/tools';
 
@@ -393,7 +393,7 @@ const abacEndpoints = API.v1
 					sort: _sort,
 					skip: offset,
 					limit: count,
-					allowDiskUse: true,
+					...getAllowDiskUse(),
 				},
 			);
 
diff --git a/apps/meteor/ee/server/api/audit.ts b/apps/meteor/ee/server/api/audit.ts
index 77d4ebf10cf7c..b6e0f7e718ada 100644
--- a/apps/meteor/ee/server/api/audit.ts
+++ b/apps/meteor/ee/server/api/audit.ts
@@ -1,5 +1,5 @@
 import type { IUser, IRoom } from '@rocket.chat/core-typings';
-import { Rooms, AuditLog, ServerEvents } from '@rocket.chat/models';
+import { Rooms, AuditLog, ServerEvents, getAllowDiskUse } from '@rocket.chat/models';
 import { isServerEventsAuditSettingsProps, ajv, ajvQuery } from '@rocket.chat/rest-typings';
 import type { PaginatedRequest, PaginatedResult } from '@rocket.chat/rest-typings';
 import { convertSubObjectsIntoPaths } from '@rocket.chat/tools';
@@ -180,7 +180,7 @@ API.v1.get(
 				sort: _sort,
 				skip: offset,
 				limit: count,
-				allowDiskUse: true,
+				...getAllowDiskUse(),
 			},
 		);
 
diff --git a/apps/meteor/ee/server/lib/engagementDashboard/channels.ts b/apps/meteor/ee/server/lib/engagementDashboard/channels.ts
index a71d7c99b21df..85df2e3589bc3 100644
--- a/apps/meteor/ee/server/lib/engagementDashboard/channels.ts
+++ b/apps/meteor/ee/server/lib/engagementDashboard/channels.ts
@@ -44,7 +44,7 @@ export const findChannelsWithNumberOfMessages = async ({
 		startOfLastWeek: convertDateToInt(startOfLastWeek),
 		endOfLastWeek: convertDateToInt(endOfLastWeek),
 		options,
-	}).toArray();
+	});
 
 	// The aggregation result may be undefined if there are no matching analytics or corresponding rooms in the period
 	if (!aggregationResult.length) {
diff --git a/apps/meteor/ee/server/models/raw/Users.ts b/apps/meteor/ee/server/models/raw/Users.ts
index 0912a3c80b03d..a572f11c706b7 100644
--- a/apps/meteor/ee/server/models/raw/Users.ts
+++ b/apps/meteor/ee/server/models/raw/Users.ts
@@ -1,5 +1,5 @@
 import type { RocketChatRecordDeleted, IUser, AvailableAgentsAggregation } from '@rocket.chat/core-typings';
-import { queryStatusAgentOnline, UsersRaw } from '@rocket.chat/models';
+import { queryStatusAgentOnline, UsersRaw, getAllowDiskUse } from '@rocket.chat/models';
 import type { Db, Collection, Filter } from 'mongodb';
 
 import { readSecondaryPreferred } from '../../../../server/database/readSecondaryPreferred';
@@ -30,19 +30,22 @@ export class UsersEE extends UsersRaw {
 					{
 						$lookup: {
 							from: 'rocketchat_livechat_department_agents',
-							let: { userId: '$_id' },
-							pipeline: [
-								{
-									$match: {
-										$expr: {
-											$and: [{ $eq: ['$$userId', '$agentId'] }, { $eq: ['$departmentId', departmentId] }],
-										},
-									},
-								},
-							],
+							localField: '_id',
+							foreignField: 'agentId',
 							as: 'department',
 						},
 					},
+					{
+						$addFields: {
+							department: {
+								$filter: {
+									input: '$department',
+									as: 'dept',
+									cond: { $eq: ['$$dept.departmentId', departmentId] },
+								},
+							},
+						},
+					},
 					{
 						$match: { department: { $size: 1 } },
 					},
@@ -61,10 +64,22 @@ export class UsersEE extends UsersRaw {
 							from: 'rocketchat_subscription',
 							localField: '_id',
 							foreignField: 'u._id',
-							pipeline: [{ $match: { $and: [{ t: 'l' }, { open: true }, { onHold: { $ne: true } }] } }],
 							as: 'subs',
 						},
 					},
+					{
+						$addFields: {
+							subs: {
+								$filter: {
+									input: '$subs',
+									as: 'sub',
+									cond: {
+										$and: [{ $eq: ['$$sub.t', 'l'] }, { $eq: ['$$sub.open', true] }, { $ne: ['$$sub.onHold', true] }],
+									},
+								},
+							},
+						},
+					},
 					{
 						$project: {
 							'agentId': '$_id',
@@ -93,7 +108,7 @@ export class UsersEE extends UsersRaw {
 					...(customFilter ? [customFilter] : []),
 					{ $project: { username: 1 } },
 				],
-				{ allowDiskUse: true, readPreference: readSecondaryPreferred() },
+				{ ...getAllowDiskUse(), readPreference: readSecondaryPreferred() },
 			)
 			.toArray();
 	}
diff --git a/apps/meteor/ee/server/patches/verifyContactChannel.ts b/apps/meteor/ee/server/patches/verifyContactChannel.ts
index 8e7a2c05cf840..567a5ef4c8b80 100644
--- a/apps/meteor/ee/server/patches/verifyContactChannel.ts
+++ b/apps/meteor/ee/server/patches/verifyContactChannel.ts
@@ -6,7 +6,7 @@ import { LivechatContacts, LivechatInquiry, LivechatRooms } from '@rocket.chat/m
 import { QueueManager } from '../../../app/livechat/server/lib/QueueManager';
 import { mergeContacts } from '../../../app/livechat/server/lib/contacts/mergeContacts';
 import { verifyContactChannel } from '../../../app/livechat/server/lib/contacts/verifyContactChannel';
-import { client, shouldRetryTransaction } from '../../../server/database/utils';
+import { client, shouldRetryTransaction, transactionOptions } from '../../../server/database/utils';
 import { contactLogger as logger } from '../../app/livechat-enterprise/server/lib/logger';
 
 type VerifyContactChannelParams = {
@@ -26,7 +26,7 @@ async function _verifyContactChannel(
 
 	const session = client.startSession();
 	try {
-		session.startTransaction();
+		session.startTransaction(transactionOptions);
 		logger.debug({ msg: 'Start verifying contact channel', contactId, visitorId, roomId });
 
 		const updater = LivechatContacts.getUpdater();
diff --git a/apps/meteor/packages/rocketchat-mongo-config/server/index.js b/apps/meteor/packages/rocketchat-mongo-config/server/index.js
index 721ae66e77a9d..357c8bb24c74e 100644
--- a/apps/meteor/packages/rocketchat-mongo-config/server/index.js
+++ b/apps/meteor/packages/rocketchat-mongo-config/server/index.js
@@ -3,6 +3,42 @@ import { PassThrough } from 'stream';
 
 import { Email } from 'meteor/email';
 import { Mongo } from 'meteor/mongo';
+import { MongoInternals } from 'meteor/mongo';
+
+// DocumentDB only supports one index build at a time per collection.
+// Serialize createIndexAsync calls at the MongoConnection level so Meteor
+// packages (accounts-base, accounts-password, accounts-oauth) don't race.
+// This package loads before accounts-base (position 53 vs 56 in .meteor/packages).
+//
+// NOTE: Meteor bundles its own copy of the mongodb driver (npm-mongo/node_modules/mongodb)
+// separate from the app's node_modules/mongodb. Patching Collection.prototype from
+// `import { Collection } from 'mongodb'` only patches the app's copy and does NOT
+// affect Meteor's internal calls. That's why we patch MongoConnection here instead.
+// The shared queue (via globalThis) is also used by @rocket.chat/models patchIndex.ts
+// to serialize BaseRaw.createIndexes() calls through the app's mongodb driver copy.
+if (process.env.DOCUMENTDB === 'true') {
+	const QUEUE_KEY = Symbol.for('rocketchat.documentdb.index.queues');
+	if (!globalThis[QUEUE_KEY]) {
+		globalThis[QUEUE_KEY] = new Map();
+	}
+	const queues = globalThis[QUEUE_KEY];
+
+	const enqueue = (collectionName, fn) => {
+		const prev = queues.get(collectionName) || Promise.resolve();
+		const next = prev.then(fn, fn);
+		queues.set(collectionName, next.catch(() => {}));
+		return next;
+	};
+
+	const mongo = MongoInternals.defaultRemoteCollectionDriver().mongo;
+	const originalCreateIndex = mongo.createIndexAsync.bind(mongo);
+
+	mongo.createIndexAsync = async function (collectionName, index, options) {
+		return enqueue(collectionName, () => originalCreateIndex(collectionName, index, options));
+	};
+	mongo.ensureIndexAsync = mongo.createIndexAsync;
+	mongo.createIndex = mongo.createIndexAsync;
+}
 
 // we always want Meteor to disable oplog tailing
 Package['disable-oplog'] = {};
diff --git a/apps/meteor/server/database/utils.ts b/apps/meteor/server/database/utils.ts
index e4b95085408cc..da57cab51559d 100644
--- a/apps/meteor/server/database/utils.ts
+++ b/apps/meteor/server/database/utils.ts
@@ -1,12 +1,22 @@
 import type { OffCallbackHandler } from '@rocket.chat/emitter';
 import { Emitter } from '@rocket.chat/emitter';
 import { MongoInternals } from 'meteor/mongo';
-import type { ClientSession, MongoError } from 'mongodb';
+import { ReadPreference } from 'mongodb';
+import type { ClientSession, MongoError, TransactionOptions } from 'mongodb';
 
 import { SystemLogger } from '../lib/logger/system';
 
 export const { db, client } = MongoInternals.defaultRemoteCollectionDriver().mongo;
 
+// MongoDB and DocumentDB require read preference `primary` inside transactions.
+// When the client is configured with e.g. `secondaryPreferred` (common in
+// read-heavy deployments and in the CI connection to DocumentDB), transactions
+// must explicitly override the read preference or they will fail with
+// "Read preference in a transaction must be primary".
+export const transactionOptions: TransactionOptions = {
+	readPreference: ReadPreference.primary,
+};
+
 /**
  * In MongoDB, errors like UnknownTransactionCommitResult and TransientTransactionError occur primarily in the context of distributed transactions
  * and are often due to temporary network issues, server failures, or timeouts. Here’s what each error means and some common causes:
@@ -71,7 +81,7 @@ export const wrapInSessionTransaction =
 
 		const dispatch = (session: ClientSession) => ee.emit('success', session);
 		try {
-			extendedSession.startTransaction();
+			extendedSession.startTransaction(transactionOptions);
 			extendedSession.once('ended', dispatch);
 
 			const result = await curriedCallback(extendedSession).apply(this, args);
diff --git a/apps/meteor/server/lib/findUsersOfRoomOrderedByRole.ts b/apps/meteor/server/lib/findUsersOfRoomOrderedByRole.ts
index e03544d3a5a03..48390c3f82a8e 100644
--- a/apps/meteor/server/lib/findUsersOfRoomOrderedByRole.ts
+++ b/apps/meteor/server/lib/findUsersOfRoomOrderedByRole.ts
@@ -1,5 +1,5 @@
 import { type IUser, ROOM_ROLE_PRIORITY_MAP, type ISubscription } from '@rocket.chat/core-typings';
-import { Subscriptions, Users } from '@rocket.chat/models';
+import { Subscriptions, Users, getAllowDiskUse } from '@rocket.chat/models';
 import { escapeRegExp } from '@rocket.chat/string-helpers';
 import type { Document, FilterOperators } from 'mongodb';
 
@@ -92,18 +92,20 @@ export async function findUsersOfRoomOrderedByRole({
 			{
 				$lookup: {
 					from: Subscriptions.getCollectionName(),
+					localField: '_id',
+					foreignField: 'u._id',
 					as: 'subscription',
-					let: { userId: '$_id', roomId: rid },
-					pipeline: [
-						{
-							$match: {
-								$expr: {
-									$and: [{ $eq: ['$rid', '$$roomId'] }, { $eq: ['$u._id', '$$userId'] }],
-								},
-							},
+				},
+			},
+			{
+				$addFields: {
+					subscription: {
+						$filter: {
+							input: '$subscription',
+							as: 'sub',
+							cond: { $eq: ['$$sub.rid', rid] },
 						},
-						{ $project: { roles: 1, status: 1, ts: 1 } },
-					],
+					},
 				},
 			},
 			{
@@ -123,9 +125,7 @@ export async function findUsersOfRoomOrderedByRole({
 				},
 			},
 		],
-		{
-			allowDiskUse: true,
-		},
+		getAllowDiskUse(),
 	);
 
 	const [members, totalCount] = await Promise.all([membersResult.toArray(), Users.countDocuments(matchUserFilter)]);
diff --git a/apps/meteor/server/lib/migrations.ts b/apps/meteor/server/lib/migrations.ts
index fd8c1a468bab4..5721f8efc3cba 100644
--- a/apps/meteor/server/lib/migrations.ts
+++ b/apps/meteor/server/lib/migrations.ts
@@ -19,7 +19,7 @@ const migrations = new Set<IMigration>();
 
 // sets the control record
 function setControl(control: Pick<IControl, 'version' | 'locked'>): Pick<IControl, 'version' | 'locked'> {
-	void Migrations.updateMany(
+	Migrations.updateMany(
 		{
 			_id: 'control',
 		},
@@ -32,7 +32,17 @@ function setControl(control: Pick<IControl, 'version' | 'locked'>): Pick<IContro
 		{
 			upsert: true,
 		},
-	);
+	).catch((e) => {
+		// E11000 on a concurrent upsert of the same _id is safe to ignore — another
+		// caller won the race and inserted the document; the $set will apply on the
+		// next call. Without this catch, the rejected promise from the fire-and-forget
+		// updateMany becomes an unhandled rejection and crashes the process when
+		// EXIT_UNHANDLEDPROMISEREJECTION is set (CI).
+		if (e?.code === 11000) {
+			return;
+		}
+		log.error({ msg: 'Failed to set migration control', err: e });
+	});
 
 	return control;
 }
diff --git a/apps/meteor/server/services/team/service.ts b/apps/meteor/server/services/team/service.ts
index 9c3c7c8b746fa..848dff050b629 100644
--- a/apps/meteor/server/services/team/service.ts
+++ b/apps/meteor/server/services/team/service.ts
@@ -1122,7 +1122,7 @@ export class TeamService extends ServiceClassInternal implements ITeamService {
 		}
 
 		const [{ totalCount: [{ count: total }] = [], paginatedResults: data = [] }] =
-			(await Rooms.findChildrenOfTeam(team._id, mainRoom._id, userId, filter, type, { skip, limit, sort }).toArray()) || [];
+			(await Rooms.findChildrenOfTeam(team._id, mainRoom._id, userId, filter, type, { skip, limit, sort })) || [];
 
 		return {
 			total,
diff --git a/docker-compose-ci.yml b/docker-compose-ci.yml
index e5f71d5937c54..4a700373e19c4 100644
--- a/docker-compose-ci.yml
+++ b/docker-compose-ci.yml
@@ -16,7 +16,7 @@ services:
       - TEST_MODE=true
       - DEBUG=${DEBUG:-}
       - EXIT_UNHANDLEDPROMISEREJECTION=true
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'MONGO_OPLOG_URL=${MONGO_OPLOG_URL:-}'
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
@@ -28,9 +28,13 @@ services:
       - Federation_Service_Enabled=true
       - 'Federation_Service_Domain=rc.host'
       - HEAP_USAGE_PERCENT=99
+      - 'DOCUMENTDB=${DOCUMENTDB:-}'
     depends_on:
-      - traefik
-      - mongo
+      traefik:
+        condition: service_started
+      mongo:
+        condition: service_started
+        required: false
     labels:
       traefik.enable: true
       traefik.http.services.rocketchat.loadbalancer.server.port: 3000
@@ -41,7 +45,10 @@ services:
       interval: 2s
       timeout: 5s
       retries: 5
-      start_period: 60s
+      # Startup against an external DocumentDB cluster is significantly slower
+      # than the local Mongo container due to network latency on every
+      # initial setup query (indexes, migrations, settings load).
+      start_period: 180s
       test: wget --no-verbose --tries=1 --spider http://127.0.0.1:3000/livez || exit 1
 
   authorization-service:
@@ -56,7 +63,7 @@ services:
         SERVICE: authorization-service
     image: ghcr.io/${LOWERCASE_REPOSITORY}/authorization-service:${DOCKER_TAG}
     environment:
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
     extra_hosts:
@@ -76,7 +83,7 @@ services:
         SERVICE: account-service
     image: ghcr.io/${LOWERCASE_REPOSITORY}/account-service:${DOCKER_TAG}
     environment:
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
     extra_hosts:
@@ -96,7 +103,7 @@ services:
         SERVICE: presence-service
     image: ghcr.io/${LOWERCASE_REPOSITORY}/presence-service:${DOCKER_TAG}
     environment:
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
     extra_hosts:
@@ -116,7 +123,7 @@ services:
         SERVICE: ddp-streamer
     image: ghcr.io/${LOWERCASE_REPOSITORY}/ddp-streamer-service:${DOCKER_TAG}
     environment:
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
     extra_hosts:
@@ -142,7 +149,7 @@ services:
         SERVICE: queue-worker
     image: ghcr.io/${LOWERCASE_REPOSITORY}/queue-worker-service:${DOCKER_TAG}
     environment:
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
     extra_hosts:
@@ -163,7 +170,7 @@ services:
     image: ghcr.io/${LOWERCASE_REPOSITORY}/omnichannel-transcript-service:${DOCKER_TAG}
     environment:
       - TEST_MODE=true
-      - MONGO_URL=mongodb://mongo:27017/rocketchat?replicaSet=rs0
+      - MONGO_URL=${DOCKER_MONGO_URL:-mongodb://mongo:27017/rocketchat?replicaSet=rs0}
       - 'TRANSPORTER=${TRANSPORTER:-}'
       - MOLECULER_LOG_LEVEL=info
     extra_hosts:
diff --git a/docs/documentdb-compatibility.md b/docs/documentdb-compatibility.md
new file mode 100644
index 0000000000000..e1054e34d850e
--- /dev/null
+++ b/docs/documentdb-compatibility.md
@@ -0,0 +1,92 @@
+# Amazon DocumentDB Compatibility
+
+This document describes the changes made to ensure compatibility with Amazon DocumentDB, which has several differences from MongoDB in terms of supported operators and features.
+
+## Environment Variable
+
+Set the `DOCUMENTDB` environment variable to `true` to enable DocumentDB compatibility mode:
+
+```bash
+DOCUMENTDB=true
+```
+
+When enabled, this flag adjusts query behavior to avoid unsupported features in Amazon DocumentDB.
+
+## Changes Overview
+
+### 1. `allowDiskUse` option removal
+
+**Problem:** Amazon DocumentDB does not support the `allowDiskUse` option for the `find` command. For aggregation pipelines, DocumentDB uses sort merge by default, making `allowDiskUse` unnecessary.
+
+**Solution:** The `getAllowDiskUse()` utility function (in `packages/models/src/allowDiskUse.ts`) returns `{ allowDiskUse: true }` when running on MongoDB and `{}` (empty object, effectively omitting the option) when `DOCUMENTDB=true`. Usage is via spread: `{ ...getAllowDiskUse(), ...otherOptions }` or passed directly as the options argument: `aggregate(pipeline, getAllowDiskUse())`.
+
+**Affected files:**
+- `packages/models/src/models/Analytics.ts`
+- `packages/models/src/models/LivechatAgentActivity.ts`
+- `packages/models/src/models/LivechatContacts.ts`
+- `packages/models/src/models/LivechatRooms.ts`
+- `packages/models/src/models/Messages.ts`
+- `packages/models/src/models/ModerationReports.ts`
+- `packages/models/src/models/Rooms.ts`
+- `packages/models/src/models/Sessions.ts`
+- `apps/meteor/app/api/server/lib/users.ts`
+- `apps/meteor/ee/server/api/abac/index.ts`
+- `apps/meteor/ee/server/api/audit.ts`
+- `apps/meteor/ee/server/models/raw/Users.ts`
+- `apps/meteor/server/lib/findUsersOfRoomOrderedByRole.ts`
+
+**Reference:** [Amazon DocumentDB - allowDiskUse](https://docs.aws.amazon.com/documentdb/latest/developerguide/how-it-works.html)
+
+### 2. `$lookup` with `let` / pipeline subqueries
+
+**Problem:** Amazon DocumentDB does not support `$lookup` stages that use `let` and `pipeline` (correlated subqueries). Only the basic `$lookup` form (`localField` / `foreignField`) is supported.
+
+**Solution:** Replaced pipeline-based `$lookup` stages with the basic `localField` / `foreignField` form, followed by additional pipeline stages (`$unwind`, `$match`, `$project`) to achieve equivalent results.
+
+**Affected files:**
+- `packages/models/src/models/LivechatRooms.ts`
+- `packages/models/src/models/Rooms.ts` (findChildrenOfTeam)
+- `packages/models/src/models/Subscriptions.ts` (findConnectedUsersExcept)
+- `packages/models/src/models/Users.ts` (getNextLeastBusyAgent, getLastAvailableAgentRouted)
+- `apps/meteor/ee/server/models/raw/Users.ts` (getUnavailableAgents)
+- `apps/meteor/server/lib/findUsersOfRoomOrderedByRole.ts`
+- `packages/models/src/models/LivechatDepartment.ts`
+
+### 3. `$facet` stage replacement
+
+**Problem:** Amazon DocumentDB has limited support for `$facet`. Certain operators within `$facet` sub-pipelines may not work as expected, and `$facet` can cause performance issues due to the lack of index usage within sub-pipelines.
+
+**Solution:** Replaced `$facet` stages with parallel aggregation calls (using `Promise.all`) — one for the data query and one for the count query. This approach also enables better index utilization.
+
+**Affected files:**
+- `packages/models/src/models/Analytics.ts`
+- `packages/models/src/models/Rooms.ts` (findChildrenOfTeam)
+- `packages/models/src/models/Sessions.ts`
+- `packages/models/src/models/LivechatRooms.ts` (getQueueMetrics)
+- `packages/models/src/models/LivechatBusinessHours.ts` (findHoursToScheduleJobs)
+- `apps/meteor/app/api/server/lib/users.ts` (users.list endpoint)
+- `apps/meteor/ee/server/models/raw/Users.ts` (findAgentsWithDepartments)
+
+### 4. `$$REMOVE` system variable replacement
+
+**Problem:** Amazon DocumentDB does not support the `$$REMOVE` system variable, which is used in `$cond` / `$ifNull` expressions to conditionally remove fields from documents.
+
+**Solution:** Replaced `$$REMOVE` usage with a two-step approach:
+1. Set the field to a sentinel value (e.g., `null` or omit it) in the `$project` / `$addFields` stage.
+2. Use a subsequent `$unset` or `$project` stage to remove the field when not needed.
+
+Alternatively, restructured the pipeline to avoid the conditional field removal entirely.
+
+**Affected files:**
+- `packages/models/src/models/Sessions.ts` (listUsers)
+- `packages/models/src/models/LivechatRooms.ts` (findAvailableSources)
+- `packages/models/src/models/LivechatDepartment.ts` (getBusinessHoursWithDepartmentStatuses)
+
+### 5. Pipeline-based `$lookup` in `LivechatDepartment.ts`
+
+**Problem:** A complex `$lookup` with pipeline was used to join and filter department data with business hours.
+
+**Solution:** Replaced with basic `$lookup` using `localField` / `foreignField`, followed by `$unwind` and `$match` stages to filter the joined data.
+
+**Affected files:**
+- `packages/models/src/models/LivechatDepartment.ts`
diff --git a/packages/model-typings/src/models/IAnalyticsModel.ts b/packages/model-typings/src/models/IAnalyticsModel.ts
index 1baec42d0c585..c6e91eb147aea 100644
--- a/packages/model-typings/src/models/IAnalyticsModel.ts
+++ b/packages/model-typings/src/models/IAnalyticsModel.ts
@@ -46,5 +46,5 @@ export interface IAnalyticsModel extends IBaseModel<IAnalytics> {
 		startOfLastWeek: number;
 		endOfLastWeek: number;
 		options?: any;
-	}): AggregationCursor<{ channels: IChannelsWithNumberOfMessagesBetweenDate[]; total: number }>;
+	}): Promise<{ channels: IChannelsWithNumberOfMessagesBetweenDate[]; total: number }[]>;
 }
diff --git a/packages/model-typings/src/models/IRoomsModel.ts b/packages/model-typings/src/models/IRoomsModel.ts
index 736ccc811c403..074482f706648 100644
--- a/packages/model-typings/src/models/IRoomsModel.ts
+++ b/packages/model-typings/src/models/IRoomsModel.ts
@@ -325,7 +325,7 @@ export interface IRoomsModel extends IBaseModel<IRoom> {
 		filter?: string,
 		type?: 'channels' | 'discussions',
 		options?: FindOptions<IRoom>,
-	): AggregationCursor<{ totalCount: { count: number }[]; paginatedResults: IRoom[] }>;
+	): Promise<{ totalCount: { count: number }[]; paginatedResults: IRoom[] }[]>;
 	resetRoomKeyAndSetE2EEQueueByRoomId(
 		roomId: string,
 		e2eKeyId: string,
diff --git a/packages/models/src/allowDiskUse.ts b/packages/models/src/allowDiskUse.ts
new file mode 100644
index 0000000000000..055a20fc86180
--- /dev/null
+++ b/packages/models/src/allowDiskUse.ts
@@ -0,0 +1,17 @@
+/**
+ * Returns an object with the `allowDiskUse` option for MongoDB aggregation/find operations.
+ *
+ * Amazon DocumentDB does not support `allowDiskUse` for `find` commands and uses
+ * sort merge by default for aggregations when `allowDiskUse` is not specified.
+ * When the `DOCUMENTDB` environment variable is set to 'true', this function
+ * returns an empty object so the option is omitted from queries.
+ *
+ * @see https://docs.aws.amazon.com/documentdb/latest/developerguide/how-it-works.html
+ */
+export function getAllowDiskUse(): { allowDiskUse: true } | Record<string, never> {
+	if (process.env.DOCUMENTDB === 'true') {
+		return {};
+	}
+
+	return { allowDiskUse: true };
+}
diff --git a/packages/models/src/filterIndexes.ts b/packages/models/src/filterIndexes.ts
new file mode 100644
index 0000000000000..5f46176908498
--- /dev/null
+++ b/packages/models/src/filterIndexes.ts
@@ -0,0 +1,74 @@
+import type { IndexDescription } from 'mongodb';
+
+/**
+ * Operators that DocumentDB does not support inside `partialFilterExpression`.
+ * DocumentDB only allows simple comparison operators ($eq, $gt, $gte, $lt, $lte)
+ * in partial filter expressions. Indexes using $exists, $type, $regex, $or, etc.
+ * fail with "Bad query specified" at index creation time.
+ *
+ * @see https://docs.aws.amazon.com/documentdb/latest/developerguide/functional-differences.html
+ */
+const UNSUPPORTED_PARTIAL_FILTER_OPERATORS = ['$exists', '$type', '$regex', '$or', '$and', '$not', '$nor', '$in', '$nin'];
+
+const containsUnsupportedOperator = (expr: unknown): boolean => {
+	if (!expr || typeof expr !== 'object') {
+		return false;
+	}
+
+	for (const [key, value] of Object.entries(expr)) {
+		if (UNSUPPORTED_PARTIAL_FILTER_OPERATORS.includes(key)) {
+			return true;
+		}
+		if (typeof value === 'object' && value !== null && containsUnsupportedOperator(value)) {
+			return true;
+		}
+	}
+	return false;
+};
+
+const isTextIndex = (index: IndexDescription): boolean => {
+	const key = index.key as Record<string, unknown> | undefined;
+	if (!key) return false;
+	return Object.values(key).some((v) => v === 'text');
+};
+
+const isUnsupportedPartialIndex = (index: IndexDescription): boolean => {
+	if (!index.partialFilterExpression) return false;
+	return containsUnsupportedOperator(index.partialFilterExpression);
+};
+
+/**
+ * Filters out indexes that DocumentDB cannot create.
+ *
+ * When `DOCUMENTDB=true`, removes:
+ *   - Text indexes (`{ field: 'text' }`) — DocumentDB has no native text search
+ *   - Partial indexes with operators outside the supported subset
+ *     (`$exists`, `$type`, `$regex`, etc.)
+ *
+ * Trade-off: the affected queries fall back to collection scans on DocumentDB,
+ * which may be slower. Functionality is preserved.
+ */
+export function filterIndexesForDocumentDB(indexes: IndexDescription[], collectionName: string): IndexDescription[] {
+	if (process.env.DOCUMENTDB !== 'true') {
+		return indexes;
+	}
+
+	const skipped: string[] = [];
+	const filtered = indexes.filter((index) => {
+		if (isTextIndex(index)) {
+			skipped.push(`text index on ${JSON.stringify(index.key)}`);
+			return false;
+		}
+		if (isUnsupportedPartialIndex(index)) {
+			skipped.push(`partial index on ${JSON.stringify(index.key)} (unsupported operator in partialFilterExpression)`);
+			return false;
+		}
+		return true;
+	});
+
+	if (skipped.length) {
+		console.warn(`[DocumentDB] Skipping ${skipped.length} unsupported index(es) on '${collectionName}':\n\t${skipped.join('\n\t')}`);
+	}
+
+	return filtered;
+}
diff --git a/packages/models/src/index.ts b/packages/models/src/index.ts
index 4805f237ef585..005d8c9a1027d 100644
--- a/packages/models/src/index.ts
+++ b/packages/models/src/index.ts
@@ -1,3 +1,4 @@
+import './patchIndex';
 import type { ILivechatDepartmentAgents, ILivechatInquiryRecord, ISubscription, RocketChatRecordDeleted } from '@rocket.chat/core-typings';
 import type {
 	IAnalyticsModel,
@@ -122,6 +123,7 @@ export * from './helpers';
 
 export { registerModel } from './proxify';
 export { type Updater, UpdaterImpl } from './updater';
+export { getAllowDiskUse } from './allowDiskUse';
 
 export const Apps = proxify<IAppsModel>('IAppsModel');
 export const AppsPersistence = proxify<IAppsPersistenceModel>('IAppsPersistenceModel');
diff --git a/packages/models/src/models/Analytics.ts b/packages/models/src/models/Analytics.ts
index a26cb50500fd3..f7a9679ef30de 100644
--- a/packages/models/src/models/Analytics.ts
+++ b/packages/models/src/models/Analytics.ts
@@ -4,6 +4,7 @@ import { Random } from '@rocket.chat/random';
 import type { AggregationCursor, FindCursor, Db, IndexDescription, FindOptions, UpdateResult, Document, Collection } from 'mongodb';
 
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 export class AnalyticsRaw extends BaseRaw<IAnalytics> implements IAnalyticsModel {
@@ -286,46 +287,34 @@ export class AnalyticsRaw extends BaseRaw<IAnalytics> implements IAnalyticsModel
 		if (options?.count) {
 			sortAndPaginationParams.push({ $limit: options.count });
 		}
-		const facet = {
-			$facet: {
-				channels: [...sortAndPaginationParams],
-				total: [{ $count: 'total' }],
-			},
-		};
-		const totalUnwind = { $unwind: '$total' };
-		const totalProject = {
-			$project: {
-				channels: '$channels',
-				total: '$total.total',
-			},
-		};
-
 		const params: Exclude<Parameters<Collection<IRoom>['aggregate']>[0], undefined> = [
 			typeAndDateMatch,
 			roomsGroup,
 			lookup,
 			roomsUnwind,
 			project,
-			facet,
-			totalUnwind,
-			totalProject,
 		];
 
-		return params;
+		return { baseParams: params, sortAndPaginationParams };
 	}
 
-	findRoomsByTypesWithNumberOfMessagesBetweenDate(params: {
+	async findRoomsByTypesWithNumberOfMessagesBetweenDate(params: {
 		types: Array<IRoom['t']>;
 		start: number;
 		end: number;
 		startOfLastWeek: number;
 		endOfLastWeek: number;
 		options?: any;
-	}): AggregationCursor<{ channels: IChannelsWithNumberOfMessagesBetweenDate[]; total: number }> {
-		const aggregationParams = this.getRoomsWithNumberOfMessagesBetweenDateQuery(params);
-		return this.col.aggregate<{ channels: IChannelsWithNumberOfMessagesBetweenDate[]; total: number }>(aggregationParams, {
-			allowDiskUse: true,
-			readPreference: readSecondaryPreferred(),
-		});
+	}): Promise<{ channels: IChannelsWithNumberOfMessagesBetweenDate[]; total: number }[]> {
+		const { baseParams, sortAndPaginationParams } = this.getRoomsWithNumberOfMessagesBetweenDateQuery(params);
+		const aggregateOptions = { ...getAllowDiskUse(), readPreference: readSecondaryPreferred() };
+
+		const [channels, countResult] = await Promise.all([
+			this.col.aggregate<IChannelsWithNumberOfMessagesBetweenDate>([...baseParams, ...sortAndPaginationParams], aggregateOptions).toArray(),
+			this.col.aggregate<{ total: number }>([...baseParams, { $count: 'total' }], aggregateOptions).toArray(),
+		]);
+
+		const total = countResult[0]?.total || 0;
+		return [{ channels, total }];
 	}
 }
diff --git a/packages/models/src/models/BaseRaw.ts b/packages/models/src/models/BaseRaw.ts
index 3c389e9cad9c1..015b0eaf01ba1 100644
--- a/packages/models/src/models/BaseRaw.ts
+++ b/packages/models/src/models/BaseRaw.ts
@@ -30,6 +30,7 @@ import type {
 } from 'mongodb';
 
 import { getCollectionName, UpdaterImpl } from '..';
+import { filterIndexesForDocumentDB } from '../filterIndexes';
 import type { Updater } from '../updater';
 import { setUpdatedAt } from './setUpdatedAt';
 
@@ -89,9 +90,15 @@ export abstract class BaseRaw<
 	private pendingIndexes: Promise<void> | undefined;
 
 	public async createIndexes() {
-		const indexes = this.modelIndexes();
+		const allIndexes = this.modelIndexes();
+
+		if (allIndexes?.length) {
+			const indexes = filterIndexesForDocumentDB(allIndexes, this.collectionName);
+
+			if (!indexes.length) {
+				return;
+			}
 
-		if (indexes?.length) {
 			if (this.pendingIndexes) {
 				await this.pendingIndexes;
 			}
diff --git a/packages/models/src/models/LivechatAgentActivity.ts b/packages/models/src/models/LivechatAgentActivity.ts
index cb0bc8172b339..f9c425835005b 100644
--- a/packages/models/src/models/LivechatAgentActivity.ts
+++ b/packages/models/src/models/LivechatAgentActivity.ts
@@ -4,6 +4,7 @@ import { parseISO, format } from 'date-fns';
 import type { AggregationCursor, Collection, Document, FindCursor, Db, WithId, IndexDescription, UpdateResult } from 'mongodb';
 
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 export class LivechatAgentActivityRaw extends BaseRaw<ILivechatAgentActivity> implements ILivechatAgentActivityModel {
@@ -233,6 +234,6 @@ export class LivechatAgentActivityRaw extends BaseRaw<ILivechatAgentActivity> im
 		if (options.count) {
 			params.push({ $limit: options.count });
 		}
-		return this.col.aggregate<ILivechatAgentActivity>(params, { allowDiskUse: true, readPreference: readSecondaryPreferred() });
+		return this.col.aggregate<ILivechatAgentActivity>(params, { ...getAllowDiskUse(), readPreference: readSecondaryPreferred() });
 	}
 }
diff --git a/packages/models/src/models/LivechatBusinessHours.ts b/packages/models/src/models/LivechatBusinessHours.ts
index 39d076cbd1951..10eb9f18a0b10 100644
--- a/packages/models/src/models/LivechatBusinessHours.ts
+++ b/packages/models/src/models/LivechatBusinessHours.ts
@@ -79,53 +79,42 @@ export class LivechatBusinessHoursRaw extends BaseRaw<ILivechatBusinessHour> imp
 		});
 	}
 
-	findHoursToScheduleJobs(): Promise<IWorkHoursCronJobsWrapper[]> {
-		return this.col
-			.aggregate([
-				{
-					$facet: {
-						start: [
-							{ $match: { active: true } },
-							{ $project: { _id: 0, workHours: 1 } },
-							{ $unwind: { path: '$workHours' } },
-							{ $match: { 'workHours.open': true } },
-							{
-								$group: {
-									_id: { day: '$workHours.start.cron.dayOfWeek' },
-									times: { $addToSet: '$workHours.start.cron.time' },
-								},
-							},
-							{
-								$project: {
-									_id: 0,
-									day: '$_id.day',
-									times: 1,
-								},
-							},
-						],
-						finish: [
-							{ $match: { active: true } },
-							{ $project: { _id: 0, workHours: 1 } },
-							{ $unwind: { path: '$workHours' } },
-							{ $match: { 'workHours.open': true } },
-							{
-								$group: {
-									_id: { day: '$workHours.finish.cron.dayOfWeek' },
-									times: { $addToSet: '$workHours.finish.cron.time' },
-								},
-							},
-							{
-								$project: {
-									_id: 0,
-									day: '$_id.day',
-									times: 1,
-								},
-							},
-						],
+	async findHoursToScheduleJobs(): Promise<IWorkHoursCronJobsWrapper[]> {
+		const basePipeline = [
+			{ $match: { active: true } },
+			{ $project: { _id: 0, workHours: 1 } },
+			{ $unwind: { path: '$workHours' } },
+			{ $match: { 'workHours.open': true } },
+		];
+
+		const [start, finish] = await Promise.all([
+			this.col
+				.aggregate([
+					...basePipeline,
+					{
+						$group: {
+							_id: { day: '$workHours.start.cron.dayOfWeek' },
+							times: { $addToSet: '$workHours.start.cron.time' },
+						},
 					},
-				},
-			])
-			.toArray() as any;
+					{ $project: { _id: 0, day: '$_id.day', times: 1 } },
+				])
+				.toArray(),
+			this.col
+				.aggregate([
+					...basePipeline,
+					{
+						$group: {
+							_id: { day: '$workHours.finish.cron.dayOfWeek' },
+							times: { $addToSet: '$workHours.finish.cron.time' },
+						},
+					},
+					{ $project: { _id: 0, day: '$_id.day', times: 1 } },
+				])
+				.toArray(),
+		]);
+
+		return [{ start, finish }] as any;
 	}
 
 	async findActiveBusinessHoursToOpen(
diff --git a/packages/models/src/models/LivechatContacts.ts b/packages/models/src/models/LivechatContacts.ts
index a48f25bc1df5e..7c8894e9a4ca3 100644
--- a/packages/models/src/models/LivechatContacts.ts
+++ b/packages/models/src/models/LivechatContacts.ts
@@ -26,6 +26,7 @@ import type {
 } from 'mongodb';
 
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 export class LivechatContactsRaw extends BaseRaw<ILivechatContact> implements ILivechatContactsModel {
@@ -181,7 +182,7 @@ export class LivechatContactsRaw extends BaseRaw<ILivechatContact> implements IL
 		return this.findPaginated(
 			{ ...match },
 			{
-				allowDiskUse: true,
+				...getAllowDiskUse(),
 				...options,
 			},
 		);
@@ -451,7 +452,7 @@ export class LivechatContactsRaw extends BaseRaw<ILivechatContact> implements IL
 					},
 				},
 			],
-			{ allowDiskUse: true, readPreference: readSecondaryPreferred() },
+			{ ...getAllowDiskUse(), readPreference: readSecondaryPreferred() },
 		);
 	}
 
diff --git a/packages/models/src/models/LivechatDepartment.ts b/packages/models/src/models/LivechatDepartment.ts
index 60263c72e2416..11d61020641f2 100644
--- a/packages/models/src/models/LivechatDepartment.ts
+++ b/packages/models/src/models/LivechatDepartment.ts
@@ -384,7 +384,7 @@ export class LivechatDepartmentRaw extends BaseRaw<ILivechatDepartment> implemen
 										],
 									},
 									then: '$_id',
-									else: '$$REMOVE',
+									else: null,
 								},
 							},
 						},
@@ -395,12 +395,22 @@ export class LivechatDepartmentRaw extends BaseRaw<ILivechatDepartment> implemen
 										$or: [{ $eq: ['$enabled', false] }, { $eq: ['$archived', true] }],
 									},
 									then: '$_id',
-									else: '$$REMOVE',
+									else: null,
 								},
 							},
 						},
 					},
 				},
+				{
+					$project: {
+						validDepartments: {
+							$filter: { input: '$validDepartments', cond: { $ne: ['$$this', null] } },
+						},
+						invalidDepartments: {
+							$filter: { input: '$invalidDepartments', cond: { $ne: ['$$this', null] } },
+						},
+					},
+				},
 			])
 			.toArray();
 	}
@@ -419,13 +429,17 @@ export class LivechatDepartmentRaw extends BaseRaw<ILivechatDepartment> implemen
 					localField: 'parentId',
 					foreignField: 'unitId',
 					as: 'monitors',
-					pipeline: [
-						{
-							$match: {
-								monitorId,
-							},
+				},
+			},
+			{
+				$addFields: {
+					monitors: {
+						$filter: {
+							input: '$monitors',
+							as: 'mon',
+							cond: { $eq: ['$$mon.monitorId', monitorId] },
 						},
-					],
+					},
 				},
 			},
 			{
diff --git a/packages/models/src/models/LivechatRooms.ts b/packages/models/src/models/LivechatRooms.ts
index 1e027dc15ed16..228b43a7a47ab 100644
--- a/packages/models/src/models/LivechatRooms.ts
+++ b/packages/models/src/models/LivechatRooms.ts
@@ -32,6 +32,7 @@ import type {
 
 import type { Updater } from '../updater';
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 /**
@@ -104,7 +105,7 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 		return this.findOne(query);
 	}
 
-	getQueueMetrics({
+	async getQueueMetrics({
 		departmentId,
 		agentId,
 		includeOfflineAgents,
@@ -124,23 +125,8 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 		const departmentsLookup = {
 			$lookup: {
 				from: 'rocketchat_livechat_department',
-				let: {
-					deptId: '$departmentId',
-				},
-				pipeline: [
-					{
-						$match: {
-							$expr: {
-								$eq: ['$_id', '$$deptId'],
-							},
-						},
-					},
-					{
-						$project: {
-							name: 1,
-						},
-					},
-				],
+				localField: 'departmentId',
+				foreignField: '_id',
 				as: 'departments',
 			},
 		};
@@ -154,31 +140,25 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 		const usersLookup = {
 			$lookup: {
 				from: 'users',
-				let: {
-					servedById: '$servedBy._id',
-				},
-				pipeline: [
-					{
-						$match: {
-							$expr: {
-								$eq: ['$_id', '$$servedById'],
-							},
-							...(!includeOfflineAgents && {
-								status: { $ne: 'offline' },
-								statusLivechat: 'available',
-							}),
-							...(agentId && { _id: agentId }),
-						},
-					},
-					{
-						$project: {
-							_id: 1,
-							username: 1,
-							status: 1,
+				localField: 'servedBy._id',
+				foreignField: '_id',
+				as: 'user',
+			},
+		};
+		const usersFilter = {
+			$addFields: {
+				user: {
+					$filter: {
+						input: '$user',
+						as: 'u',
+						cond: {
+							$and: [
+								...(!includeOfflineAgents ? [{ $ne: ['$$u.status', 'offline'] }, { $eq: ['$$u.statusLivechat', 'available'] }] : []),
+								...(agentId ? [{ $eq: ['$$u._id', agentId] }] : []),
+							],
 						},
 					},
-				],
-				as: 'user',
+				},
 			},
 		};
 		const usersUnwind = {
@@ -213,7 +193,7 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 				chats: 1,
 			},
 		};
-		const firstParams = [match, departmentsLookup, departmentsUnwind, usersLookup, usersUnwind];
+		const firstParams = [match, departmentsLookup, departmentsUnwind, usersLookup, usersFilter, usersUnwind];
 		const sort: Document = { $sort: options.sort || { chats: -1 } };
 		const pagination = [sort];
 
@@ -224,16 +204,16 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 			pagination.push({ $limit: options.count });
 		}
 
-		const facet = {
-			$facet: {
-				sortedResults: pagination,
-				totalCount: [{ $group: { _id: null, total: { $sum: 1 } } }],
-			},
-		};
+		const baseParams = [...firstParams, usersGroup, project];
+		const aggregateOptions = { readPreference: readSecondaryPreferred(), ...getAllowDiskUse() };
 
-		const params = [...firstParams, usersGroup, project, facet];
+		const [sortedResults, countResult] = await Promise.all([
+			this.col.aggregate([...baseParams, ...pagination], aggregateOptions).toArray(),
+			this.col.aggregate<{ total: number }>([...baseParams, { $count: 'total' }], aggregateOptions).toArray(),
+		]);
 
-		return this.col.aggregate(params, { readPreference: readSecondaryPreferred(), allowDiskUse: true }).toArray();
+		const totalCount = countResult.length ? [{ total: countResult[0].total }] : [];
+		return [{ sortedResults, totalCount }];
 	}
 
 	async findAllNumberOfAbandonedRooms({
@@ -721,7 +701,7 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 		if (options.count) {
 			params.push({ $limit: options.count });
 		}
-		return this.col.aggregate(params, { allowDiskUse: true, readPreference: readSecondaryPreferred() }).toArray();
+		return this.col.aggregate(params, { ...getAllowDiskUse(), readPreference: readSecondaryPreferred() }).toArray();
 	}
 
 	countAllOpenChatsBetweenDate({ start, end, departmentId }: { start: Date; end: Date; departmentId?: string }) {
@@ -1554,7 +1534,7 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 								if: {
 									$eq: ['$source.type', 'app'],
 								},
-								then: '$$REMOVE',
+								then: null,
 								else: { type: '$source.type' },
 							},
 						},
@@ -1565,7 +1545,7 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 								if: {
 									$eq: ['$source.type', 'app'],
 								},
-								else: '$$REMOVE',
+								else: null,
 								then: {
 									type: '$source.type',
 									id: '$source.id',
@@ -1578,6 +1558,12 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 					},
 				},
 			},
+			{
+				$addFields: {
+					types: { $filter: { input: '$types', cond: { $ne: ['$$this', null] } } },
+					apps: { $filter: { input: '$apps', cond: { $ne: ['$$this', null] } } },
+				},
+			},
 			{
 				$project: {
 					_id: 0,
@@ -2170,31 +2156,25 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 						...extraMatchers,
 					},
 				},
-				{ $addFields: { roomId: '$_id' } },
 				{
 					$lookup: {
 						from: 'rocketchat_message',
-						// mongo doesn't like _id as variable name here :(
-						let: { roomId: '$roomId' },
-						pipeline: [
-							{
-								$match: {
-									$expr: {
-										$and: [
-											{
-												$eq: ['$$roomId', '$rid'],
-											},
-											{
-												// this is similar to do { $exists: false }
-												$lte: ['$t', null],
-											},
-											...(extraQuery ? [extraQuery] : []),
-										],
-									},
+						localField: '_id',
+						foreignField: 'rid',
+						as: 'messages',
+					},
+				},
+				{
+					$addFields: {
+						messages: {
+							$filter: {
+								input: '$messages',
+								as: 'msg',
+								cond: {
+									$and: [{ $lte: ['$$msg.t', null] }, ...(extraQuery ? [extraQuery] : [])],
 								},
 							},
-						],
-						as: 'messages',
+						},
 					},
 				},
 				{
@@ -2247,32 +2227,25 @@ export class LivechatRoomsRaw extends BaseRaw<IOmnichannelRoom> implements ILive
 						...(departmentId && departmentId !== 'undefined' && { departmentId }),
 					},
 				},
-				{ $addFields: { roomId: '$_id' } },
 				{
 					$lookup: {
 						from: 'rocketchat_message',
-						// mongo doesn't like _id as variable name here :(
-						let: { roomId: '$roomId' },
-						pipeline: [
-							{
-								$match: {
-									$expr: {
-										$and: [
-											{
-												$eq: ['$$roomId', '$rid'],
-											},
-											{
-												// this is similar to do { $exists: false }
-												$lte: ['$t', null],
-											},
-										],
-									},
-								},
-							},
-						],
+						localField: '_id',
+						foreignField: 'rid',
 						as: 'messages',
 					},
 				},
+				{
+					$addFields: {
+						messages: {
+							$filter: {
+								input: '$messages',
+								as: 'msg',
+								cond: { $lte: ['$$msg.t', null] },
+							},
+						},
+					},
+				},
 				{
 					$unwind: {
 						path: '$messages',
diff --git a/packages/models/src/models/Messages.ts b/packages/models/src/models/Messages.ts
index e16cb35fd41ee..16563806c66aa 100644
--- a/packages/models/src/models/Messages.ts
+++ b/packages/models/src/models/Messages.ts
@@ -30,6 +30,7 @@ import type {
 } from 'mongodb';
 
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 type DeepWritable<T> = T extends (...args: any) => any
@@ -247,7 +248,7 @@ export class MessagesRaw extends BaseRaw<IMessage> implements IMessagesModel {
 			params.push({ $limit: options.count });
 		}
 		return this.col.aggregate<{ _id: string | null; numberOfTransferredRooms: number }>(params, {
-			allowDiskUse: true,
+			...getAllowDiskUse(),
 			readPreference: readSecondaryPreferred(),
 		});
 	}
@@ -327,7 +328,7 @@ export class MessagesRaw extends BaseRaw<IMessage> implements IMessagesModel {
 		if (options.count) {
 			params.push({ $limit: options.count });
 		}
-		return this.col.aggregate(params, { allowDiskUse: true, readPreference: readSecondaryPreferred() }).toArray();
+		return this.col.aggregate(params, { ...getAllowDiskUse(), readPreference: readSecondaryPreferred() }).toArray();
 	}
 
 	findLivechatClosedMessages(rid: IRoom['_id'], searchTerm?: string, options?: FindOptions<IMessage>): FindPaginated<FindCursor<IMessage>> {
diff --git a/packages/models/src/models/ModerationReports.ts b/packages/models/src/models/ModerationReports.ts
index d700d78cfa5c8..346624da824db 100644
--- a/packages/models/src/models/ModerationReports.ts
+++ b/packages/models/src/models/ModerationReports.ts
@@ -10,6 +10,7 @@ import type { FindPaginated, IModerationReportsModel, PaginationParams } from '@
 import type { AggregationCursor, Collection, Db, Document, FindCursor, FindOptions, IndexDescription, UpdateResult } from 'mongodb';
 
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 export class ModerationReportsRaw extends BaseRaw<IModerationReport> implements IModerationReportsModel {
@@ -136,7 +137,7 @@ export class ModerationReportsRaw extends BaseRaw<IModerationReport> implements
 			},
 		];
 
-		return this.col.aggregate(params, { allowDiskUse: true });
+		return this.col.aggregate(params, getAllowDiskUse());
 	}
 
 	findUserReports(
@@ -193,7 +194,7 @@ export class ModerationReportsRaw extends BaseRaw<IModerationReport> implements
 			},
 		];
 
-		return this.col.aggregate(pipeline, { allowDiskUse: true, readPreference: readSecondaryPreferred() });
+		return this.col.aggregate(pipeline, { ...getAllowDiskUse(), readPreference: readSecondaryPreferred() });
 	}
 
 	async getTotalUniqueReportedUsers(latest: Date, oldest: Date, selector: string, isMessageReports?: boolean): Promise<number> {
diff --git a/packages/models/src/models/Rooms.ts b/packages/models/src/models/Rooms.ts
index f2a1d07a7e552..f1e97678b150d 100644
--- a/packages/models/src/models/Rooms.ts
+++ b/packages/models/src/models/Rooms.ts
@@ -30,6 +30,7 @@ import type {
 
 import { Subscriptions } from '../index';
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 import type { Updater } from '../updater';
 
@@ -605,7 +606,7 @@ export class RoomsRaw extends BaseRaw<IRoom> implements IRoomsModel {
 	}): AggregationCursor<IChannelsWithNumberOfMessagesBetweenDate> {
 		const aggregationParams = this.getChannelsWithNumberOfMessagesBetweenDateQuery(params);
 		return this.col.aggregate<IChannelsWithNumberOfMessagesBetweenDate>(aggregationParams, {
-			allowDiskUse: true,
+			...getAllowDiskUse(),
 			readPreference: readSecondaryPreferred(),
 		});
 	}
@@ -2212,16 +2213,16 @@ export class RoomsRaw extends BaseRaw<IRoom> implements IRoomsModel {
 		return this.updateMany(query, update);
 	}
 
-	findChildrenOfTeam(
+	async findChildrenOfTeam(
 		teamId: string,
 		teamRoomId: string,
 		userId: string,
 		filter?: string,
 		type?: 'channels' | 'discussions',
 		options?: FindOptions<IRoom>,
-	): AggregationCursor<{ totalCount: { count: number }[]; paginatedResults: IRoom[] }> {
+	): Promise<{ totalCount: { count: number }[]; paginatedResults: IRoom[] }[]> {
 		const nameFilter = filter ? new RegExp(escapeRegExp(filter), 'i') : undefined;
-		return this.col.aggregate<{ totalCount: { count: number }[]; paginatedResults: IRoom[] }>([
+		const baseQuery = [
 			{
 				$match: {
 					$and: [
@@ -2238,36 +2239,22 @@ export class RoomsRaw extends BaseRaw<IRoom> implements IRoomsModel {
 			{
 				$lookup: {
 					from: 'rocketchat_subscription',
-					let: {
-						roomId: '$_id',
-					},
-					pipeline: [
-						{
-							$match: {
-								$and: [
-									{
-										$expr: {
-											$eq: ['$rid', '$$roomId'],
-										},
-									},
-									{
-										$expr: {
-											$eq: ['$u._id', userId],
-										},
-									},
-									{
-										$expr: {
-											$ne: ['$t', 'c'],
-										},
-									},
-								],
+					localField: '_id',
+					foreignField: 'rid',
+					as: 'subscription',
+				},
+			},
+			{
+				$addFields: {
+					subscription: {
+						$filter: {
+							input: '$subscription',
+							as: 'sub',
+							cond: {
+								$and: [{ $eq: ['$$sub.u._id', userId] }, { $ne: ['$$sub.t', 'c'] }],
 							},
 						},
-						{
-							$project: { _id: 1 },
-						},
-					],
-					as: 'subscription',
+					},
 				},
 			},
 			{
@@ -2284,13 +2271,14 @@ export class RoomsRaw extends BaseRaw<IRoom> implements IRoomsModel {
 			},
 			{ $project: { subscription: 0 } },
 			{ $sort: options?.sort || { ts: 1 } },
-			{
-				$facet: {
-					totalCount: [{ $count: 'count' }],
-					paginatedResults: [{ $skip: options?.skip || 0 }, { $limit: options?.limit || 50 }],
-				},
-			},
+		];
+
+		const [paginatedResults, countResult] = await Promise.all([
+			this.col.aggregate<IRoom>([...baseQuery, { $skip: options?.skip || 0 }, { $limit: options?.limit || 50 }]).toArray(),
+			this.col.aggregate<{ count: number }>([...baseQuery, { $count: 'count' }]).toArray(),
 		]);
+
+		return [{ totalCount: countResult, paginatedResults }];
 	}
 
 	findAllByTypesAndDiscussionAndTeam(
diff --git a/packages/models/src/models/Sessions.ts b/packages/models/src/models/Sessions.ts
index 3763bf38b457a..c2adb92ac5b42 100644
--- a/packages/models/src/models/Sessions.ts
+++ b/packages/models/src/models/Sessions.ts
@@ -12,7 +12,7 @@ import type {
 	RocketChatRecordDeleted,
 } from '@rocket.chat/core-typings';
 import type { ISessionsModel } from '@rocket.chat/model-typings';
-import type { PaginatedResult, WithItemCount } from '@rocket.chat/rest-typings';
+import type { PaginatedResult } from '@rocket.chat/rest-typings';
 import type {
 	AggregationCursor,
 	AnyBulkWriteOperation,
@@ -30,6 +30,7 @@ import type {
 
 import { getCollectionName } from '../index';
 import { BaseRaw } from './BaseRaw';
+import { getAllowDiskUse } from '../allowDiskUse';
 import { readSecondaryPreferred } from '../readSecondaryPreferred';
 
 type DestructuredDate = { year: number; month: number; day: number };
@@ -124,7 +125,7 @@ const matchBasedOnDate = (start: DestructuredDate, end: DestructuredDate): Filte
 
 const getGroupSessionsByHour = (
 	_id: { range: string; day: string; month: string; year: string } | string,
-): { listGroup: object; countGroup: object } => {
+): { listGroup: object; filterNulls: object; countGroup: object } => {
 	const isOpenSession = { $not: ['$session.closedAt'] };
 	const isAfterLoginAt = { $gte: ['$range', { $hour: '$session.loginAt' }] };
 	const isBeforeClosedAt = { $lte: ['$range', { $hour: '$session.closedAt' }] };
@@ -139,20 +140,26 @@ const getGroupSessionsByHour = (
 							$or: [{ $and: [isOpenSession, isAfterLoginAt] }, { $and: [isAfterLoginAt, isBeforeClosedAt] }],
 						},
 						'$session.userId',
-						'$$REMOVE',
+						null,
 					],
 				},
 			},
 		},
 	};
 
+	const filterNulls = {
+		$addFields: {
+			usersList: { $filter: { input: '$usersList', cond: { $ne: ['$$this', null] } } },
+		},
+	};
+
 	const countGroup = {
 		$addFields: {
 			users: { $size: '$usersList' },
 		},
 	};
 
-	return { listGroup, countGroup };
+	return { listGroup, filterNulls, countGroup };
 };
 
 const getSortByFullDate = (): { year: number; month: number; day: number } => ({
@@ -273,7 +280,7 @@ export const aggregates = {
 				devices: ISession['device'][];
 				_computedAt: string;
 			}
-		>(pipeline, { allowDiskUse: true });
+		>(pipeline, getAllowDiskUse());
 	},
 
 	async getUniqueUsersOfYesterday(
@@ -424,7 +431,7 @@ export const aggregates = {
 						},
 					},
 				],
-				{ allowDiskUse: true },
+				getAllowDiskUse(),
 			)
 			.toArray();
 	},
@@ -574,7 +581,7 @@ export const aggregates = {
 						},
 					},
 				],
-				{ allowDiskUse: true },
+				getAllowDiskUse(),
 			)
 			.toArray();
 	},
@@ -678,7 +685,7 @@ export const aggregates = {
 						},
 					},
 				],
-				{ allowDiskUse: true },
+				getAllowDiskUse(),
 			)
 			.toArray();
 	},
@@ -827,26 +834,14 @@ export class SessionsRaw extends BaseRaw<ISession> implements ISessionsModel {
 			},
 		};
 
-		const facetOperator = {
-			$facet: {
-				docs: [sortOperator, ...skipOperator, limitOperator, ...customSortOp],
-				count: [
-					{
-						$count: 'total',
-					},
-				],
-			},
-		};
+		const baseQuery = [matchOperator, sortOperator, groupOperator, projectOperator];
 
-		const queryArray = [matchOperator, sortOperator, groupOperator, projectOperator, facetOperator];
-
-		const [
-			{
-				docs: sessions,
-				count: [{ total } = { total: 0 }],
-			},
-		] = await this.col.aggregate<WithItemCount<{ docs: DeviceManagementSession[] }>>(queryArray).toArray();
+		const [sessions, countResult] = await Promise.all([
+			this.col.aggregate<DeviceManagementSession>([...baseQuery, sortOperator, ...skipOperator, limitOperator, ...customSortOp]).toArray(),
+			this.col.aggregate<{ total: number }>([...baseQuery, { $count: 'total' }]).toArray(),
+		]);
 
+		const total = countResult[0]?.total || 0;
 		return { sessions, total, count, offset };
 	}
 
@@ -953,26 +948,25 @@ export class SessionsRaw extends BaseRaw<ISession> implements ISessionsModel {
 			},
 		};
 
-		const facetOperator = {
-			$facet: {
-				docs: [sortOperator, ...skipOperator, limitOperator, lookupOperator, unwindOperator, projectOperator, ...customSortOp],
-				count: [
-					{
-						$count: 'total',
-					},
-				],
-			},
-		};
-
-		const queryArray = [matchOperator, sortOperator, groupOperator, facetOperator];
-
-		const [
-			{
-				docs: sessions,
-				count: [{ total } = { total: 0 }],
-			},
-		] = await this.col.aggregate<WithItemCount<{ docs: DeviceManagementPopulatedSession[] }>>(queryArray).toArray();
-
+		const baseQuery = [matchOperator, sortOperator, groupOperator];
+
+		const [sessions, countResult] = await Promise.all([
+			this.col
+				.aggregate<DeviceManagementPopulatedSession>([
+					...baseQuery,
+					sortOperator,
+					...skipOperator,
+					limitOperator,
+					lookupOperator,
+					unwindOperator,
+					projectOperator,
+					...customSortOp,
+				])
+				.toArray(),
+			this.col.aggregate<{ total: number }>([...baseQuery, { $count: 'total' }]).toArray(),
+		]);
+
+		const total = countResult[0]?.total || 0;
 		return { sessions, total, count, offset };
 	}
 
@@ -1143,7 +1137,7 @@ export class SessionsRaw extends BaseRaw<ISession> implements ISessionsModel {
 			.aggregate<{
 				hour: number;
 				users: number;
-			}>([match, rangeProject, unwind, groups.listGroup, groups.countGroup, presentationProject, sort])
+			}>([match, rangeProject, unwind, groups.listGroup, groups.filterNulls, groups.countGroup, presentationProject, sort])
 			.toArray();
 	}
 
@@ -1245,7 +1239,7 @@ export class SessionsRaw extends BaseRaw<ISession> implements ISessionsModel {
 				month: number;
 				year: number;
 				users: number;
-			}>([match, rangeProject, unwind, groups.listGroup, groups.countGroup, presentationProject, sort])
+			}>([match, rangeProject, unwind, groups.listGroup, groups.filterNulls, groups.countGroup, presentationProject, sort])
 			.toArray();
 	}
 
diff --git a/packages/models/src/models/Subscriptions.ts b/packages/models/src/models/Subscriptions.ts
index 5a7bbdfc7e51a..4ae7334b10adc 100644
--- a/packages/models/src/models/Subscriptions.ts
+++ b/packages/models/src/models/Subscriptions.ts
@@ -453,11 +453,9 @@ export class SubscriptionsRaw extends BaseRaw<ISubscription> implements ISubscri
 					{
 						$lookup: {
 							from: 'rocketchat_subscription',
+							localField: '_id',
+							foreignField: 'rid',
 							as: 'subscription',
-							let: {
-								rid: '$_id',
-							},
-							pipeline: [{ $match: { '$expr': { $eq: ['$rid', '$$rid'] }, 'u._id': { $ne: userId } } }],
 						},
 					},
 					// Unwind the subscription so we have a separate document for each
@@ -466,6 +464,12 @@ export class SubscriptionsRaw extends BaseRaw<ISubscription> implements ISubscri
 							path: '$subscription',
 						},
 					},
+					// Filter out the requesting user's own subscriptions
+					{
+						$match: {
+							'subscription.u._id': { $ne: userId },
+						},
+					},
 					// Group the data by user id, keeping track of how many documents each user had
 					{
 						$group: {
@@ -475,34 +479,36 @@ export class SubscriptionsRaw extends BaseRaw<ISubscription> implements ISubscri
 							},
 						},
 					},
-					// Load the data for the subscription's user, ignoring those who don't match the search terms
+					// Load the data for the subscription's user
 					{
 						$lookup: {
 							from: 'users',
+							localField: '_id',
+							foreignField: '_id',
 							as: 'user',
-							let: { id: '$_id' },
-							pipeline: [
-								{
-									$match: {
-										$expr: { $eq: ['$_id', '$$id'] },
-										...extraConditions,
-										active: true,
-										username: {
-											$exists: true,
-											...(exceptions.length > 0 && { $nin: exceptions }),
-										},
-										...(searchTerm && orStatement.length > 0 && { $or: orStatement }),
-									},
-								},
-							],
 						},
 					},
-					// Discard documents that didn't load any user data in the previous step:
+					// Discard documents that didn't load any user data
 					{
 						$unwind: {
 							path: '$user',
 						},
 					},
+					// Filter users by search terms and conditions
+					{
+						$match: {
+							...Object.fromEntries(Object.entries(extraConditions).map(([k, v]) => [`user.${k}`, v])),
+							'user.active': true,
+							'user.username': {
+								$exists: true,
+								...(exceptions.length > 0 && { $nin: exceptions }),
+							},
+							...(searchTerm &&
+								orStatement.length > 0 && {
+									$or: orStatement.map((cond) => Object.fromEntries(Object.entries(cond).map(([k, v]) => [`user.${k}`, v]))),
+								}),
+						},
+					},
 					// Use group to organize the data at the same time that we pick what to project to the end result
 					{
 						$group: {
diff --git a/packages/models/src/models/Users.ts b/packages/models/src/models/Users.ts
index 95cc31246380a..1e0a6d9bd36b5 100644
--- a/packages/models/src/models/Users.ts
+++ b/packages/models/src/models/Users.ts
@@ -245,7 +245,7 @@ export class UsersRaw extends BaseRaw<IUser, DefaultFields<IUser>> implements IU
 		return this.findPaginated<T>(query, options);
 	}
 
-	findAgentsWithDepartments<T extends Document = ILivechatAgent>(
+	async findAgentsWithDepartments<T extends Document = ILivechatAgent>(
 		role: IRole['_id'][] | IRole['_id'],
 		query: Filter<IUser>,
 		options?: FindOptions<IUser>,
@@ -284,15 +284,17 @@ export class UsersRaw extends BaseRaw<IUser, DefaultFields<IUser>> implements IU
 					departments: { $push: '$departments.departmentId' },
 				},
 			},
-			{
-				$facet: {
-					sortedResults: [{ $sort: options?.sort }, { $skip: options?.skip }, options?.limit && { $limit: options.limit }],
-					totalCount: [{ $group: { _id: null, total: { $sum: 1 } } }],
-				},
-			},
 		];
 
-		return this.col.aggregate<{ sortedResults: (T & { departments: string[] })[]; totalCount: { total: number }[] }>(aggregate).toArray();
+		const paginationStages = [{ $sort: options?.sort }, { $skip: options?.skip }, ...(options?.limit ? [{ $limit: options.limit }] : [])];
+
+		const [sortedResults, countResult] = await Promise.all([
+			this.col.aggregate<T & { departments: string[] }>([...aggregate, ...paginationStages]).toArray(),
+			this.col.aggregate<{ total: number }>([...aggregate, { $count: 'total' }]).toArray(),
+		]);
+
+		const totalCount = countResult.length ? [{ total: countResult[0].total }] : [];
+		return [{ sortedResults, totalCount }];
 	}
 
 	findOneByUsernameAndRoomIgnoringCase(username: string | RegExp, rid: string, options?: FindOptions<IUser>) {
@@ -567,19 +569,22 @@ export class UsersRaw extends BaseRaw<IUser, DefaultFields<IUser>> implements IU
 					{
 						$lookup: {
 							from: 'rocketchat_livechat_department_agents',
-							let: { userId: '$_id' },
-							pipeline: [
-								{
-									$match: {
-										$expr: {
-											$and: [{ $eq: ['$$userId', '$agentId'] }, { $eq: ['$departmentId', department] }],
-										},
-									},
-								},
-							],
+							localField: '_id',
+							foreignField: 'agentId',
 							as: 'department',
 						},
 					},
+					{
+						$addFields: {
+							department: {
+								$filter: {
+									input: '$department',
+									as: 'dept',
+									cond: { $eq: ['$$dept.departmentId', department] },
+								},
+							},
+						},
+					},
 					{
 						$match: { department: { $size: 1 } },
 					},
@@ -592,22 +597,26 @@ export class UsersRaw extends BaseRaw<IUser, DefaultFields<IUser>> implements IU
 			{
 				$lookup: {
 					from: 'rocketchat_subscription',
-					let: { id: '$_id' },
-					pipeline: [
-						{
-							$match: {
-								$expr: {
-									$and: [
-										{ $eq: ['$u._id', '$$id'] },
-										{ $eq: ['$open', true] },
-										{ $ne: ['$onHold', true] },
-										{ ...(department && { $eq: ['$department', department] }) },
-									],
-								},
+					localField: '_id',
+					foreignField: 'u._id',
+					as: 'subs',
+				},
+			},
+			{
+				$addFields: {
+					subs: {
+						$filter: {
+							input: '$subs',
+							as: 'sub',
+							cond: {
+								$and: [
+									{ $eq: ['$$sub.open', true] },
+									{ $ne: ['$$sub.onHold', true] },
+									...(department ? [{ $eq: ['$$sub.department', department] }] : []),
+								],
 							},
 						},
-					],
-					as: 'subs',
+					},
 				},
 			},
 			{
@@ -647,19 +656,22 @@ export class UsersRaw extends BaseRaw<IUser, DefaultFields<IUser>> implements IU
 					{
 						$lookup: {
 							from: 'rocketchat_livechat_department_agents',
-							let: { userId: '$_id' },
-							pipeline: [
-								{
-									$match: {
-										$expr: {
-											$and: [{ $eq: ['$$userId', '$agentId'] }, { $eq: ['$departmentId', department] }],
-										},
-									},
-								},
-							],
+							localField: '_id',
+							foreignField: 'agentId',
 							as: 'department',
 						},
 					},
+					{
+						$addFields: {
+							department: {
+								$filter: {
+									input: '$department',
+									as: 'dept',
+									cond: { $eq: ['$$dept.departmentId', department] },
+								},
+							},
+						},
+					},
 					{
 						$match: { department: { $size: 1 } },
 					},
diff --git a/packages/models/src/patchIndex.ts b/packages/models/src/patchIndex.ts
new file mode 100644
index 0000000000000..1fb0697194548
--- /dev/null
+++ b/packages/models/src/patchIndex.ts
@@ -0,0 +1,50 @@
+/**
+ * Amazon DocumentDB only supports one index build at a time per collection.
+ * This patch serializes createIndex/createIndexes calls at the native
+ * MongoDB driver level (app's node_modules/mongodb copy), covering calls
+ * from Rocket.Chat models (BaseRaw) and EE microservices.
+ *
+ * Meteor packages (accounts-base, accounts-password) use a separate bundled
+ * copy of the mongodb driver and are patched independently in the
+ * rocketchat:mongo-config Meteor package via MongoConnection.
+ *
+ * Both patches share the same queue via a globalThis-keyed Map so builds
+ * for the same collection are serialized across all code paths.
+ *
+ * Safe to import multiple times — the patch is applied only once.
+ */
+import { Collection } from 'mongodb';
+
+const PATCHED = Symbol.for('rocketchat.documentdb.index.patch');
+const QUEUE_KEY = Symbol.for('rocketchat.documentdb.index.queues');
+
+if (process.env.DOCUMENTDB === 'true' && !(Collection as any)[PATCHED]) {
+	(Collection as any)[PATCHED] = true;
+
+	const g = globalThis as any;
+	if (!g[QUEUE_KEY]) {
+		g[QUEUE_KEY] = new Map<string, Promise<unknown>>();
+	}
+	const queues: Map<string, Promise<unknown>> = g[QUEUE_KEY];
+
+	const enqueue = <T>(collectionName: string, fn: () => Promise<T>): Promise<T> => {
+		const prev = queues.get(collectionName) ?? Promise.resolve();
+		const next = prev.then(fn, fn);
+		queues.set(
+			collectionName,
+			// eslint-disable-next-line @typescript-eslint/no-empty-function
+			next.catch(() => {}),
+		);
+		return next;
+	};
+
+	const originalCreateIndex = Collection.prototype.createIndex;
+	Collection.prototype.createIndex = function (this: Collection, ...args: Parameters<Collection['createIndex']>) {
+		return enqueue(this.collectionName, () => originalCreateIndex.apply(this, args));
+	} as typeof Collection.prototype.createIndex;
+
+	const originalCreateIndexes = Collection.prototype.createIndexes;
+	Collection.prototype.createIndexes = function (this: Collection, ...args: Parameters<Collection['createIndexes']>) {
+		return enqueue(this.collectionName, () => originalCreateIndexes.apply(this, args));
+	} as typeof Collection.prototype.createIndexes;
+}