feat: Allow disabling of threaded view

Signed-off-by: SebastianKrupinski <krupinskis05@gmail.com>

appinfo/routes.php

@@ -345,6 +345,11 @@ return [
 			'url' => '/api/settings/importance-classification-default',
 			'verb' => 'PUT'
 		],
+		[
+			'name' => 'settings#setLayoutMessageView',
+			'url' => '/api/settings/layout-message-view',
+			'verb' => 'PUT'
+		],
 		[
 			'name' => 'trusted_senders#setTrusted',
 			'url' => '/api/trustedsenders/{email}',

lib/Contracts/IMailSearch.php

@@ -21,6 +21,8 @@ use OCP\IUser;
 interface IMailSearch {
 	public const ORDER_NEWEST_FIRST = 'DESC';
 	public const ORDER_OLDEST_FIRST = 'ASC';
+	public const VIEW_SINGLETON = 'singleton';
+	public const VIEW_THREADED = 'threaded';
 	/**
 	 * @throws DoesNotExistException
 	 * @throws ClientException
@@ -37,6 +39,7 @@ interface IMailSearch {
 	 * @param string|null $filter
 	 * @param int|null $cursor
 	 * @param int|null $limit
+	 * @param string|null $view
 	 *
 	 * @return Message[]
 	 *
@@ -48,7 +51,8 @@ interface IMailSearch {
 		string $sortOrder,
 		?string $filter,
 		?int $cursor,
-		?int $limit): array;
+		?int $limit,
+		?string $view): array;
 
 	/**
 	 * Run a search through all mailboxes of a user.

lib/Controller/MessagesController.php

@@ -124,6 +124,7 @@ class MessagesController extends Controller {
 	 * @param int $cursor
 	 * @param string $filter
 	 * @param int|null $limit
+	 * @param string $view returns messages in requested view ('singleton' or 'threaded')
 	 *
 	 * @return JSONResponse
 	 *
@@ -134,7 +135,8 @@ class MessagesController extends Controller {
 	public function index(int $mailboxId,
 		?int $cursor = null,
 		?string $filter = null,
-		?int $limit = null): JSONResponse {
+		?int $limit = null,
+		?string $view = null): JSONResponse {
 		try {
 			$mailbox = $this->mailManager->getMailbox($this->currentUserId, $mailboxId);
 			$account = $this->accountService->find($this->currentUserId, $mailbox->getAccountId());
@@ -143,17 +145,21 @@ class MessagesController extends Controller {
 		}
 
 		$this->logger->debug("loading messages of mailbox <$mailboxId>");
+		$sort = $this->preferences->getPreference($this->currentUserId, 'sort-order', 'newest') === 'newest' ? IMailSearch::ORDER_NEWEST_FIRST: IMailSearch::ORDER_OLDEST_FIRST;
+		
+		$view = $view === 'singleton' ? IMailSearch::VIEW_SINGLETON : IMailSearch::VIEW_THREADED;
 
-		$order = $this->preferences->getPreference($this->currentUserId, 'sort-order', 'newest') === 'newest' ? 'DESC': 'ASC';
+		$messages = $this->mailSearch->findMessages(
+			$account,
+			$mailbox,
+			$sort,
+			$filter === '' ? null : $filter,
+			$cursor,
+			$limit,
+			$view
+		);
 		return new JSONResponse(
-			$this->mailSearch->findMessages(
-				$account,
-				$mailbox,
-				$order,
-				$filter === '' ? null : $filter,
-				$cursor,
-				$limit
-			)
+			$messages
 		);
 	}
 

lib/Controller/PageController.php

@@ -211,6 +211,7 @@ class PageController extends Controller {
 			'app-version' => $this->config->getAppValue('mail', 'installed_version'),
 			'external-avatars' => $this->preferences->getPreference($this->currentUserId, 'external-avatars', 'true'),
 			'layout-mode' => $this->preferences->getPreference($this->currentUserId, 'layout-mode', 'vertical-split'),
+			'layout-message-view' => $this->preferences->getPreference($this->currentUserId, 'layout-message-view', $this->config->getAppValue('mail', 'layout_message_view', 'threaded')),
 			'reply-mode' => $this->preferences->getPreference($this->currentUserId, 'reply-mode', 'top'),
 			'collect-data' => $this->preferences->getPreference($this->currentUserId, 'collect-data', 'true'),
 			'search-priority-body' => $this->preferences->getPreference($this->currentUserId, 'search-priority-body', 'false'),

lib/Controller/SettingsController.php

@@ -124,4 +124,9 @@ class SettingsController extends Controller {
 		return new JSONResponse([]);
 	}
 
+	public function setLayoutMessageView(string $value): JSONResponse {
+		$this->config->setAppValue('mail', 'layout_message_view', $value);
+		return new JSONResponse([]);
+	}
+
 }

lib/Db/MessageMapper.php

@@ -808,21 +808,23 @@ class MessageMapper extends QBMapper {
 		} else {
 			$select = $qb->select(['m.id', 'm.sent_at']);
 		}
+	
+		$select->from($this->getTableName(), 'm');
 
-		$selfJoin = $select->expr()->andX(
-			$select->expr()->eq('m.mailbox_id', 'm2.mailbox_id', IQueryBuilder::PARAM_INT),
-			$select->expr()->eq('m.thread_root_id', 'm2.thread_root_id', IQueryBuilder::PARAM_INT),
-			$select->expr()->orX(
-				$select->expr()->lt('m.sent_at', 'm2.sent_at', IQueryBuilder::PARAM_INT),
-				$select->expr()->andX(
-					$select->expr()->eq('m.sent_at', 'm2.sent_at', IQueryBuilder::PARAM_INT),
-					$select->expr()->lt('m.message_id', 'm2.message_id', IQueryBuilder::PARAM_STR),
+		if ($query->getThreaded()) {
+			$selfJoin = $select->expr()->andX(
+				$select->expr()->eq('m.mailbox_id', 'm2.mailbox_id', IQueryBuilder::PARAM_INT),
+				$select->expr()->eq('m.thread_root_id', 'm2.thread_root_id', IQueryBuilder::PARAM_INT),
+				$select->expr()->orX(
+					$select->expr()->lt('m.sent_at', 'm2.sent_at', IQueryBuilder::PARAM_INT),
+					$select->expr()->andX(
+						$select->expr()->eq('m.sent_at', 'm2.sent_at', IQueryBuilder::PARAM_INT),
+						$select->expr()->lt('m.message_id', 'm2.message_id', IQueryBuilder::PARAM_STR),
+					),
 				),
-			),
-		);
-
-		$select->from($this->getTableName(), 'm')
-			->leftJoin('m', $this->getTableName(), 'm2', $selfJoin);
+			);
+			$select->leftJoin('m', $this->getTableName(), 'm2', $selfJoin);
+		}
 
 		if (!empty($query->getFrom())) {
 			$select->innerJoin('m', 'mail_recipients', 'r0', 'm.id = r0.message_id');
@@ -1008,7 +1010,9 @@ class MessageMapper extends QBMapper {
 			);
 		}
 
-		$select->andWhere($qb->expr()->isNull('m2.id'));
+		if ($query->getThreaded()) {
+			$select->andWhere($qb->expr()->isNull('m2.id'));
+		}
 
 		if ($sortOrder === 'ASC') {
 			$select->orderBy('m.sent_at', $sortOrder);

lib/Listener/AccountSynchronizedThreadUpdaterListener.php

@@ -10,6 +10,7 @@ declare(strict_types=1);
 namespace OCA\Mail\Listener;
 
 use Generator;
+use OCA\Mail\Contracts\IUserPreferences;
 use OCA\Mail\Db\MessageMapper;
 use OCA\Mail\Events\SynchronizationEvent;
 use OCA\Mail\IMAP\Threading\Container;
@@ -17,6 +18,7 @@ use OCA\Mail\IMAP\Threading\DatabaseMessage;
 use OCA\Mail\IMAP\Threading\ThreadBuilder;
 use OCP\EventDispatcher\Event;
 use OCP\EventDispatcher\IEventListener;
+
 use function array_chunk;
 use function gc_collect_cycles;
 use function iterator_to_array;
@@ -27,16 +29,11 @@ use function iterator_to_array;
 class AccountSynchronizedThreadUpdaterListener implements IEventListener {
 	private const WRITE_IDS_CHUNK_SIZE = 500;
 
-	/** @var MessageMapper */
-	private $mapper;
-
-	/** @var ThreadBuilder */
-	private $builder;
-
-	public function __construct(MessageMapper $mapper,
-		ThreadBuilder $builder) {
-		$this->mapper = $mapper;
-		$this->builder = $builder;
+	public function __construct(
+		private IUserPreferences $preferences,
+		private MessageMapper $mapper,
+		private ThreadBuilder $builder,
+	) {
 	}
 
 	public function handle(Event $event): void {
@@ -45,6 +42,13 @@ class AccountSynchronizedThreadUpdaterListener implements IEventListener {
 			return;
 		}
 		$logger = $event->getLogger();
+		$userId = $event->getAccount()->getUserId();
+		
+		if ($this->preferences->getPreference($userId, 'layout-message-view', 'threaded') !== 'threaded') {
+			$event->getLogger()->debug('Skipping threading as the user prefers a flat view');
+			return;
+		}
+
 		if (!$event->isRebuildThreads()) {
 			$event->getLogger()->debug('Skipping threading as there were no significant changes');
 			return;

lib/Service/Search/MailSearch.php

@@ -80,6 +80,7 @@ class MailSearch implements IMailSearch {
 	 * @param string|null $filter
 	 * @param int|null $cursor
 	 * @param int|null $limit
+	 * @param string|null $view
 	 *
 	 * @return Message[]
 	 *
@@ -91,7 +92,8 @@ class MailSearch implements IMailSearch {
 		string $sortOrder,
 		?string $filter,
 		?int $cursor,
-		?int $limit): array {
+		?int $limit,
+		?string $view): array {
 		if ($mailbox->hasLocks($this->timeFactory->getTime())) {
 			throw MailboxLockedException::from($mailbox);
 		}
@@ -103,6 +105,9 @@ class MailSearch implements IMailSearch {
 		if ($cursor !== null) {
 			$query->setCursor($cursor);
 		}
+		if ($view !== null) {
+			$query->setThreaded($view === self::VIEW_THREADED);
+		}
 		// In flagged we don't want anything but flagged messages
 		if ($mailbox->isSpecialUse(Horde_Imap_Client::SPECIALUSE_FLAGGED)) {
 			$query->addFlag(Flag::is(Flag::FLAGGED));

lib/Service/Search/SearchQuery.php

@@ -12,6 +12,8 @@ namespace OCA\Mail\Service\Search;
 class SearchQuery {
 	/** @var int|null */
 	private $cursor;
+	
+	private bool $threaded = true;
 
 	/** @var Flag[] */
 	private $flags = [];
@@ -72,6 +74,14 @@ class SearchQuery {
 		$this->cursor = $cursor;
 	}
 
+	public function getThreaded(): bool {
+		return $this->threaded;
+	}
+	
+	public function setThreaded(bool $threaded): void {
+		$this->threaded = $threaded;
+	}
+
 	public function getMatch(): string {
 		return $this->match;
 	}

lib/Settings/AdminSettings.php

@@ -80,6 +80,12 @@ class AdminSettings implements ISettings {
 			$this->config->getAppValue('mail', 'allow_new_mail_accounts', 'yes') === 'yes'
 		);
 
+		$this->initialStateService->provideInitialState(
+			Application::APP_ID,
+			'layout_message_view',
+			$this->config->getAppValue('mail', 'layout_message_view', 'threaded')
+		);
+
 		$this->initialStateService->provideInitialState(
 			Application::APP_ID,
 			'llm_processing',

src/components/AppSettingsMenu.vue

@@ -72,6 +72,24 @@
 					{{ t('mail', 'Horizontal split') }}
 				</NcCheckboxRadioSwitch>
 
+				<h6>{{ t('mail', 'Message View Mode') }}</h6>
+				<div class="sorting">
+					<NcCheckboxRadioSwitch type="radio"
+						name="message_view_mode_radio"
+						value="threaded"
+						:checked="layoutMessageView"
+						@update:checked="setLayoutMessageView('threaded')">
+						{{ t('mail', 'Show all messages in thread') }}
+					</NcCheckboxRadioSwitch>
+					<NcCheckboxRadioSwitch type="radio"
+						name="message_view_mode_radio"
+						value="singleton"
+						:checked="layoutMessageView"
+						@update:checked="setLayoutMessageView('singleton')">
+						{{ t('mail', 'Show only the selected message') }}
+					</NcCheckboxRadioSwitch>
+				</div>
+
 				<h6>{{ t('mail', 'Sorting') }}</h6>
 				<div class="sorting">
 					<NcCheckboxRadioSwitch class="sorting__switch"
@@ -398,6 +416,9 @@ export default {
 		layoutMode() {
 			return this.mainStore.getPreference('layout-mode', 'vertical-split')
 		},
+		layoutMessageView() {
+			return this.mainStore.getPreference('layout-message-view')
+		},
 	},
 	watch: {
 		showSettings(value) {
@@ -439,6 +460,16 @@ export default {
 				Logger.error('Could not save preferences', { error })
 			}
 		},
+		async setLayoutMessageView(value) {
+			try {
+				await this.mainStore.savePreference({
+					key: 'layout-message-view',
+					value,
+				})
+			} catch (error) {
+				Logger.error('Could not save preferences', { error })
+			}
+		},
 		async onOpen() {
 			this.showSettings = true
 		},

src/components/Envelope.vue

@@ -190,7 +190,12 @@
 					<template #icon>
 						<OpenInNewIcon :size="16" />
 					</template>
-					{{ t('mail', 'Move thread') }}
+					<template v-if="layoutMessageViewThreaded">
+						{{ t('mail', 'Move thread') }}
+					</template>
+					<template v-else>
+						{{ t('mail', 'Move Message') }}
+					</template>
 				</ActionButton>
 				<ActionButton v-if="showArchiveButton && hasArchiveAcl"
 					:close-after-click="true"
@@ -199,7 +204,12 @@
 					<template #icon>
 						<ArchiveIcon :size="16" />
 					</template>
-					{{ t('mail', 'Archive thread') }}
+					<template v-if="layoutMessageViewThreaded">
+						{{ t('mail', 'Archive thread') }}
+					</template>
+					<template v-else>
+						{{ t('mail', 'Archive message') }}
+					</template>
 				</ActionButton>
 				<ActionButton v-if="hasDeleteAcl"
 					:close-after-click="true"
@@ -207,7 +217,12 @@
 					<template #icon>
 						<DeleteIcon :size="16" />
 					</template>
-					{{ t('mail', 'Delete thread') }}
+					<template v-if="layoutMessageViewThreaded">
+						{{ t('mail', 'Delete thread') }}
+					</template>
+					<template v-else>
+						{{ t('mail', 'Delete message') }}
+					</template>
 				</ActionButton>
 				<ActionButton :close-after-click="false"
 					@click="showMoreActionOptions">
@@ -311,7 +326,7 @@
 			<MoveModal v-if="showMoveModal"
 				:account="account"
 				:envelopes="[data]"
-				:move-thread="true"
+				:move-thread="listViewThreaded"
 				@move="onMove"
 				@close="onCloseMoveModal" />
 			<EventModal v-if="showEventModal"
@@ -493,6 +508,9 @@ export default {
 		oneLineLayout() {
 			return this.overwriteOneLineMobile ? false : this.mainStore.getPreference('layout-mode', 'vertical-split') === 'no-split'
 		},
+		layoutMessageViewThreaded() {
+			return this.mainStore.getPreference('layout-message-view', 'threaded') === 'threaded'
+		},
 		hasMultipleRecipients() {
 			if (!this.account) {
 				console.error('account is undefined', {
@@ -773,9 +791,15 @@ export default {
 			this.$emit('delete', this.data.databaseId)
 
 			try {
-				await this.mainStore.deleteThread({
-					envelope: this.data,
-				})
+				if (this.layoutMessageViewThreaded) {
+					await this.mainStore.deleteThread({
+						envelope: this.data,
+					})
+				} else {
+					await this.mainStore.deleteMessage({
+						id: this.data.databaseId,
+					})
+				}
 			} catch (error) {
 				showError(await matchError(error, {
 					[NoTrashMailboxConfiguredError.getName()]() {
@@ -807,10 +831,17 @@ export default {
 			this.$emit('archive', this.data.databaseId)
 
 			try {
-				await this.mainStore.moveThread({
-					envelope: this.data,
-					destMailboxId: this.account.archiveMailboxId,
-				})
+				if (this.layoutMessageViewThreaded) {
+					await this.mainStore.moveThread({
+						envelope: this.data,
+						destMailboxId: this.account.archiveMailboxId,
+					})
+				} else {
+					await this.mainStore.moveMessage({
+						id: this.data.databaseId,
+						destMailboxId: this.account.archiveMailboxId,
+					})
+				}
 			} catch (error) {
 				logger.error('could not archive message', error)
 				showError(t('mail', 'Could not archive message'))
@@ -825,11 +856,19 @@ export default {
 			}
 
 			try {
-				await this.mainStore.snoozeThread({
-					envelope: this.data,
-					unixTimestamp: timestamp / 1000,
-					destMailboxId: this.account.snoozeMailboxId,
-				})
+				if (this.layoutMessageViewThreaded) {
+					await this.mainStore.snoozeThread({
+						envelope: this.data,
+						unixTimestamp: timestamp / 1000,
+						destMailboxId: this.account.snoozeMailboxId,
+					})
+				} else {
+					await this.mainStore.snoozeMessage({
+						id: this.data.databaseId,
+						unixTimestamp: timestamp / 1000,
+						destMailboxId: this.account.snoozeMailboxId,
+					})
+				}
 				showSuccess(t('mail', 'Thread was snoozed'))
 			} catch (error) {
 				logger.error('could not snooze thread', error)
@@ -841,9 +880,15 @@ export default {
 			this.setSelected(false)
 
 			try {
-				await this.mainStore.unSnoozeThread({
-					envelope: this.data,
-				})
+				if (this.layoutMessageViewThreaded) {
+					await this.mainStore.unSnoozeThread({
+						envelope: this.data,
+					})
+				} else {
+					await this.mainStore.unSnoozeMessage({
+						id: this.data.databaseId,
+					})
+				}
 				showSuccess(t('mail', 'Thread was unsnoozed'))
 			} catch (error) {
 				logger.error('Could not unsnooze thread', error)

src/components/NavigationMailbox.vue

@@ -8,6 +8,7 @@
 		:id="genId(mailbox)"
 		:key="genId(mailbox)"
 		v-droppable-mailbox="{
+			mainStore: mainStore,
 			mailboxId: mailbox.databaseId,
 			accountId: mailbox.accountId,
 			isValidDropTarget,

src/components/Thread.vue

@@ -126,6 +126,10 @@ export default {
 				return []
 			}
 
+			if (this.mainStore.getPreference('layout-message-view', 'threaded') === 'singleton') {
+				return [envelope]
+			}
+
 			const envelopes = this.mainStore.getEnvelopesByThreadRootId(envelope.accountId, envelope.threadRootId)
 			if (envelopes.length === 0) {
 				return []
@@ -281,11 +285,12 @@ export default {
 			this.expandedThreads = [this.threadId]
 			this.errorMessage = ''
 			this.error = undefined
-			await this.fetchThread()
+			if (this.mainStore.getPreference('layout-message-view', 'threaded') === 'threaded') {
+				await this.fetchThread()
+			}
 			this.updateParticipantsToDisplay()
 			this.updateSummary()
 			this.loadedThreads = 0
-
 		},
 		async fetchThread() {
 			this.loading = true

src/components/settings/AdminSettings.vue

@@ -253,6 +253,36 @@
 			</article>
 			<MicrosoftAdminOauthSettings :tenant-id="microsoftOauthTenantId" :client-id="microsoftOauthClientId" />
 		</div>
+		<div class="app-description">
+			<h3>{{ t('mail', 'User Interface Preference Defaults') }}</h3>
+			<article>
+				<p>
+					{{ t('mail', 'These settings are used to pre-configure the user interface preferences they can be overridden by the user in the mail settings') }}
+				</p>
+			</article>
+			<br>
+			<article>
+				<p>
+					{{ t('mail', 'Message View Mode') }}
+				</p>
+				<p>
+					<NcCheckboxRadioSwitch type="radio"
+						name="message_view_mode_radio"
+						value="threaded"
+						:checked.sync="layoutMessageView"
+						@update:checked="setLayoutMessageView('threaded')">
+						{{ t('mail', 'Show all messages in thread') }}
+					</NcCheckboxRadioSwitch>
+					<NcCheckboxRadioSwitch type="radio"
+						name="message_view_mode_radio"
+						value="singleton"
+						:checked.sync="layoutMessageView"
+						@update:checked="setLayoutMessageView('singleton')">
+						{{ t('mail', 'Show only the selected message') }}
+					</NcCheckboxRadioSwitch>
+				</p>
+			</article>
+		</div>
 	</SettingsSection>
 </template>
 
@@ -278,6 +308,7 @@ import {
 	updateLlmEnabled,
 	updateEnabledSmartReply,
 	setImportanceClassificationEnabledByDefault,
+	setLayoutMessageView,
 } from '../../service/SettingsService.js'
 
 const googleOauthClientId = loadState('mail', 'google_oauth_client_id', null) ?? undefined
@@ -342,6 +373,7 @@ export default {
 			isLlmFreePromptConfigured: loadState('mail', 'enabled_llm_free_prompt_backend'),
 			isClassificationEnabledByDefault: loadState('mail', 'llm_processing', true),
 			isImportanceClassificationEnabledByDefault: loadState('mail', 'importance_classification_default', true),
+			layoutMessageView: loadState('mail', 'layout_message_view'),
 		}
 	},
 	methods: {
@@ -410,6 +442,9 @@ export default {
 				logger.error('Could not save default classification setting', { error })
 			}
 		},
+		async setLayoutMessageView(value) {
+			await setLayoutMessageView(value)
+		},
 	},
 }
 </script>

src/directives/drag-and-drop/droppable-mailbox/droppable-mailbox.js

@@ -2,20 +2,15 @@
  * SPDX-FileCopyrightText: 2020 Nextcloud GmbH and Nextcloud contributors
  * SPDX-License-Identifier: AGPL-3.0-or-later
  */
-import useMainStore from '../../../store/mainStore.js'
 import logger from '../../../logger.js'
 import dragEventBus from '../util/dragEventBus.js'
 
-import { createPinia, setActivePinia } from 'pinia'
-
-setActivePinia(createPinia())
-const mainStore = useMainStore()
-
 export class DroppableMailbox {
 
 	constructor(el, componentInstance, options) {
 		this.el = el
 		this.options = options
+		this.mainStore = options.mainStore
 		this.registerListeners.bind(this)(el)
 		this.setInitialAttributes()
 	}
@@ -149,10 +144,17 @@ export class DroppableMailbox {
 		item.setAttribute('draggable-envelope', 'pending')
 
 		try {
-			await mainStore.moveThread({
-				envelope,
-				destMailboxId: this.options.mailboxId,
-			})
+			if (this.mainStore.getPreference('layout-message-view') === 'threaded') {
+				await this.mainStore.moveThread({
+					envelope,
+					destMailboxId: this.options.mailboxId,
+				})
+			} else {
+				await this.mainStore.moveMessage({
+					id: envelope.databaseId,
+					destMailboxId: this.options.mailboxId,
+				})
+			}
 		} catch (error) {
 			item.removeAttribute('draggable-envelope')
 			logger.error('could not move messages', error)

src/init.js

@@ -70,6 +70,10 @@ export default function initAfterAppCreation() {
 		key: 'layout-mode',
 		value: preferences['layout-mode'],
 	})
+	mainStore.savePreferenceMutation({
+		key: 'layout-message-view',
+		value: preferences['layout-message-view'],
+	})
 	mainStore.savePreferenceMutation({
 		key: 'follow-up-reminders',
 		value: preferences['follow-up-reminders'],

src/service/MessageService.js

@@ -32,7 +32,7 @@ export function fetchEnvelope(accountId, id) {
 		})
 }
 
-export function fetchEnvelopes(accountId, mailboxId, query, cursor, limit) {
+export function fetchEnvelopes(accountId, mailboxId, query, cursor, limit, sort, view) {
 	const url = generateUrl('/apps/mail/api/messages')
 	const params = {
 		mailboxId,
@@ -47,6 +47,12 @@ export function fetchEnvelopes(accountId, mailboxId, query, cursor, limit) {
 	if (cursor) {
 		params.cursor = cursor
 	}
+	if (sort) {
+		params.sort = sort
+	}
+	if (view) {
+		params.view = view
+	}
 
 	return axios
 		.get(url, {

src/service/SettingsService.js

@@ -89,3 +89,16 @@ export const setImportanceClassificationEnabledByDefault = async (enabledByDefau
 		enabledByDefault,
 	})
 }
+
+/**
+ * @param {boolean} value
+ * @return {Promise<void>}
+ */
+export const setLayoutMessageView = async (value) => {
+	const url = generateUrl('/apps/mail/api/settings/layout-message-view')
+	const data = {
+		value,
+	}
+	const resp = await axios.put(url, data)
+	return resp.data
+}

src/store/mainStore/actions.js

@@ -667,6 +667,8 @@ export default function mainStoreActions() {
 								mailboxId: mb.databaseId,
 								query,
 								addToUnifiedMailboxes: false,
+								sort: this.getPreference('sort-order'),
+								view: this.getPreference('layout-message-view'),
 							}),
 						),
 						Promise.all.bind(Promise),
@@ -701,7 +703,7 @@ export default function mainStoreActions() {
 							}),
 						),
 					),
-				)(mailbox.accountId, mailboxId, query, undefined, PAGE_SIZE, this.getPreference('sort-order'))
+				)(mailbox.accountId, mailboxId, query, undefined, PAGE_SIZE, this.getPreference('sort-order'), this.getPreference('layout-message-view'))
 			})
 		},
 		async fetchNextEnvelopePage({
@@ -1819,12 +1821,18 @@ export default function mainStoreActions() {
 		 * @return {Array} list of envelope ids
 		 */
 		appendOrReplaceEnvelopeId(existing, envelope) {
-			const index = existing.findIndex((id) => this.envelopes[id].threadRootId === envelope.threadRootId)
-			if (index === -1) {
+
+			if (this.getPreference('layout-message-view') === 'singleton') {
 				existing.push(envelope.databaseId)
 			} else {
-				existing[index] = envelope.databaseId
+				const index = existing.findIndex((id) => this.envelopes[id].threadRootId === envelope.threadRootId)
+				if (index === -1) {
+					existing.push(envelope.databaseId)
+				} else {
+					existing[index] = envelope.databaseId
+				}
 			}
+
 			return existing
 		},
 		savePreferenceMutation({

tests/Unit/Controller/PageControllerTest.php

@@ -168,7 +168,7 @@ class PageControllerTest extends TestCase {
 		$account1 = $this->createMock(Account::class);
 		$account2 = $this->createMock(Account::class);
 		$mailbox = $this->createMock(Mailbox::class);
-		$this->preferences->expects($this->exactly(10))
+		$this->preferences->expects($this->exactly(11))
 			->method('getPreference')
 			->willReturnMap([
 				[$this->userId, 'account-settings', '[]', json_encode([])],
@@ -179,6 +179,7 @@ class PageControllerTest extends TestCase {
 				[$this->userId, 'search-priority-body', 'false', 'false'],
 				[$this->userId, 'start-mailbox-id', null, '123'],
 				[$this->userId, 'layout-mode', 'vertical-split', 'vertical-split'],
+				[$this->userId, 'layout-message-view', 'threaded', 'threaded'],
 				[$this->userId, 'follow-up-reminders', 'true', 'true'],
 				[$this->userId, 'internal-addresses', 'false', 'false'],
 			]);
@@ -257,10 +258,11 @@ class PageControllerTest extends TestCase {
 				['version', '0.0.0', '26.0.0'],
 				['app.mail.attachment-size-limit', 0, 123],
 			]);
-		$this->config->expects($this->exactly(6))
+		$this->config->expects($this->exactly(7))
 			->method('getAppValue')
 			->withConsecutive(
 				[ 'mail', 'installed_version' ],
+				['mail', 'layout_message_view' ],
 				['mail', 'google_oauth_client_id' ],
 				['mail', 'microsoft_oauth_client_id' ],
 				['mail', 'microsoft_oauth_tenant_id' ],
@@ -268,6 +270,7 @@ class PageControllerTest extends TestCase {
 				['mail', 'allow_new_mail_accounts', 'yes'],
 			)->willReturnOnConsecutiveCalls(
 				$this->returnValue('1.2.3'),
+				$this->returnValue('threaded'),
 				$this->returnValue(''),
 				$this->returnValue(''),
 				$this->returnValue(''),
@@ -321,6 +324,7 @@ class PageControllerTest extends TestCase {
 					'tag-classified-messages' => 'false',
 					'search-priority-body' => 'false',
 					'layout-mode' => 'vertical-split',
+					'layout-message-view' => 'threaded',
 					'follow-up-reminders' => 'true',
 				]],
 				['prefill_displayName', 'Jane Doe'],

tests/Unit/Service/Search/MailSearchTest.php

@@ -81,6 +81,7 @@ class MailSearchTest extends TestCase {
 			'DESC',
 			null,
 			null,
+			null,
 			null
 		);
 	}
@@ -97,6 +98,7 @@ class MailSearchTest extends TestCase {
 			'DESC',
 			null,
 			null,
+			null,
 			null
 		);
 	}
@@ -117,6 +119,7 @@ class MailSearchTest extends TestCase {
 			'DESC',
 			null,
 			null,
+			null,
 			null
 		);
 
@@ -156,6 +159,7 @@ class MailSearchTest extends TestCase {
 			'DESC',
 			'my search',
 			null,
+			null,
 			null
 		);
 
@@ -198,6 +202,7 @@ class MailSearchTest extends TestCase {
 			'DESC',
 			'my search',
 			null,
+			null,
 			null
 		);
 

tests/Unit/Settings/AdminSettingsTest.php

@@ -37,7 +37,7 @@ class AdminSettingsTest extends TestCase {
 	}
 
 	public function testGetForm() {
-		$this->serviceMock->getParameter('initialStateService')->expects($this->exactly(12))
+		$this->serviceMock->getParameter('initialStateService')->expects($this->exactly(13))
 			->method('provideInitialState')
 			->withConsecutive(
 				[
@@ -55,6 +55,11 @@ class AdminSettingsTest extends TestCase {
 					'allow_new_mail_accounts',
 					$this->anything()
 				],
+				[
+					Application::APP_ID,
+					'layout_message_view',
+					$this->anything()
+				],
 				[
 					Application::APP_ID,
 					'llm_processing',