diff --git a/appinfo/routes.php b/appinfo/routes.php
index 1022f74c..142b7a73 100644
--- a/appinfo/routes.php
+++ b/appinfo/routes.php
@@ -44,6 +44,7 @@
 		['name' => 'chattyLLM#updateSessionTitle', 'url' => '/chat/update_session', 'verb' => 'PATCH'],
 		['name' => 'chattyLLM#deleteSession', 'url' => '/chat/delete_session', 'verb' => 'DELETE'],
 		['name' => 'chattyLLM#getSessions', 'url' => '/chat/sessions', 'verb' => 'GET'],
+		['name' => 'chattyLLM#searchChat', 'url' => '/chat/search', 'verb' => 'GET'],
 		['name' => 'chattyLLM#newMessage', 'url' => '/chat/new_message', 'verb' => 'PUT'],
 		['name' => 'chattyLLM#deleteMessage', 'url' => '/chat/delete_message', 'verb' => 'DELETE'],
 		['name' => 'chattyLLM#getMessages', 'url' => '/chat/messages', 'verb' => 'GET'],
diff --git a/lib/Controller/ChattyLLMController.php b/lib/Controller/ChattyLLMController.php
index e996cb0e..59a516cb 100644
--- a/lib/Controller/ChattyLLMController.php
+++ b/lib/Controller/ChattyLLMController.php
@@ -311,6 +311,39 @@ public function getSessions(): JSONResponse {
 		}
 	}
 
+	/**
+	 * Search chat messages by content
+	 *
+	 * Returns sessions that contain matching messages.
+	 *
+	 * @param string $query Search query (min 2 characters)
+	 * @return JSONResponse<Http::STATUS_OK, array{sessions: list<AssistantChatSession>}, array{}>|JSONResponse<Http::STATUS_UNAUTHORIZED|Http::STATUS_INTERNAL_SERVER_ERROR, array{error: string}, array{}>
+	 *
+	 * 200: Search results
+	 * 401: Not logged in
+	 * 500: Failed to search
+	 */
+	#[NoAdminRequired]
+	#[OpenAPI(scope: OpenAPI::SCOPE_DEFAULT, tags: ['chat_api'])]
+	public function searchChat(string $query = ''): JSONResponse {
+		if ($this->userId === null) {
+			return new JSONResponse(['error' => $this->l10n->t('User not logged in')], Http::STATUS_UNAUTHORIZED);
+		}
+
+		$query = trim($query);
+		if (empty($query) || strlen($query) < 2) {
+			return new JSONResponse(['sessions' => []]);
+		}
+
+		try {
+			$sessions = $this->sessionMapper->searchSessionsByMessageContent($this->userId, $query);
+			return new JSONResponse(['sessions' => $sessions]);
+		} catch (\OCP\DB\Exception $e) {
+			$this->logger->warning('Failed to search chat messages', ['exception' => $e]);
+            return new JSONResponse(['error' => $this->l10n->t('Failed to search chat sessions')], Http::STATUS_INTERNAL_SERVER_ERROR);
+		}
+	}
+
 	/**
 	 * Add a message
 	 *
diff --git a/lib/Db/ChattyLLM/SessionMapper.php b/lib/Db/ChattyLLM/SessionMapper.php
index 9006bcf6..4a167eab 100644
--- a/lib/Db/ChattyLLM/SessionMapper.php
+++ b/lib/Db/ChattyLLM/SessionMapper.php
@@ -185,4 +185,24 @@ public function updateSessionIsRemembered(?string $userId, int $sessionId, bool
 		$session->setIsRemembered($is_remembered);
 		$this->update($session);
 	}
+
+	/**
+	 * @return array<Session>
+	 * @throws \OCP\DB\Exception
+	 */
+	public function searchSessionsByMessageContent(string $userId, string $query): array {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('s.id', 's.user_id', 's.title', 's.timestamp', 's.agency_conversation_token', 's.agency_pending_actions', 's.summary', 's.is_summary_up_to_date', 's.is_remembered')
+			->from($this->getTableName(), 's')
+			->innerJoin('s', 'assistant_chat_msgs', 'm', $qb->expr()->eq('s.id', 'm.session_id'))
+			->where($qb->expr()->eq('s.user_id', $qb->createPositionalParameter($userId, IQueryBuilder::PARAM_STR)))
+			->andWhere($qb->expr()->in('m.role', $qb->createParameter('roles')))
+			->andWhere($qb->expr()->iLike('m.content', $qb->createPositionalParameter('%' . $query . '%', IQueryBuilder::PARAM_STR)))
+			->groupBy('s.id')
+			->orderBy('s.timestamp', 'DESC');
+
+		$qb->setParameter('roles', ['human', 'assistant'], IQueryBuilder::PARAM_STR_ARRAY);
+
+		return $this->findEntities($qb);
+	}
 }
diff --git a/src/components/ChattyLLM/ChattyLLMInputForm.vue b/src/components/ChattyLLM/ChattyLLMInputForm.vue
index b6164487..30d9200f 100644
--- a/src/components/ChattyLLM/ChattyLLMInputForm.vue
+++ b/src/components/ChattyLLM/ChattyLLMInputForm.vue
@@ -6,6 +6,17 @@
 	<div class="container">
 		<NcAppNavigation>
 			<NcAppNavigationList>
+				<div class="chat-search">
+					<NcTextField
+						:model-value="searchQuery"
+						:placeholder="t('assistant', 'Search in conversations')"
+						:show-trailing-button="searchQuery.length > 0"
+						trailing-button-icon="close"
+						:trailing-button-label="t('assistant', 'Clear search')"
+						@update:model-value="onSearchInput"
+						@trailing-button-click="clearSearch" />
+					<NcLoadingIcon v-if="searchLoading" class="chat-search__loading" :size="20" />
+				</div>
 				<NcAppNavigationNew :text="t('assistant', 'New conversation')"
 					variant="secondary"
 					@click="newSession">
@@ -17,11 +28,11 @@
 					<NcLoadingIcon :size="30" />
 					{{ t('assistant', 'Loading conversations…') }}
 				</div>
-				<div v-else-if="sessions != null && sessions.length === 0" class="unloaded-sessions">
-					{{ t('assistant', 'No conversations yet') }}
+				<div v-else-if="displayedSessions != null && displayedSessions.length === 0" class="unloaded-sessions">
+					{{ searchQuery ? t('assistant', 'No matching conversations') : t('assistant', 'No conversations yet') }}
 				</div>
 				<NcAppNavigationItem
-					v-for="session in sessions"
+					v-for="session in displayedSessions"
 					v-else
 					:key="'conversation' + session.id"
 					:active="session.id === active?.id"
@@ -85,7 +96,7 @@
 					</NcActions>
 				</div>
 			</div>
-			<div class="session-area__chat-area">
+			<div ref="chatArea" class="session-area__chat-area">
 				<NoSession v-if="loading.newSession"
 					:name="t('assistant', 'Creating a new conversation')"
 					description="">
@@ -120,8 +131,12 @@
 					<ConversationBox :messages="messages"
 						:loading="loading"
 						:slow-pickup="slowPickup"
+						:search-query="searchQuery"
+						:matched-message-ids="matchedMessageIds"
+						:highlighted-message-index="highlightedMessageIndex"
 						@regenerate="runRegenerationTask"
-						@delete="deleteMessage" />
+						@delete="deleteMessage"
+						@highlight-end="highlightedMessageIndex = null" />
 					<div v-if="messages != null && messages.length > 0 && !loading.llmGeneration && !loading.newHumanMessage && messages[messages.length - 1]?.role === 'human'" class="session-area__chat-area__active-session__utility-button">
 						<NcButton
 							:aria-label="t('assistant', 'Retry response generation')"
@@ -138,6 +153,30 @@
 				class="session-area__agency-confirmation"
 				@confirm="onAgencyAnswer(true)"
 				@reject="onAgencyAnswer(false)" />
+			<div v-if="searchMatchNavVisible" class="session-area__search-match-nav">
+				<span class="session-area__search-match-nav__label">{{ t('assistant', 'Search matches') }}</span>
+				<span class="session-area__search-match-nav__count">{{ searchMatchCurrentDisplay }}/{{ matchingMessageIndices.length }}</span>
+				<div class="session-area__search-match-nav__arrows">
+					<NcButton
+						:aria-label="t('assistant', 'Previous match')"
+						:disabled="searchMatchIndex <= 0"
+						class="session-area__search-match-nav__arrow"
+						@click="goToPrevMatch">
+						<template #icon>
+							<ChevronUpIcon />
+						</template>
+					</NcButton>
+					<NcButton
+						:aria-label="t('assistant', 'Next match')"
+						:disabled="searchMatchIndex >= matchingMessageIndices.length - 1"
+						class="session-area__search-match-nav__arrow"
+						@click="goToNextMatch">
+						<template #icon>
+							<ChevronDownIcon />
+						</template>
+					</NcButton>
+				</div>
+			</div>
 			<p class="session-area__disclaimer">
 				{{ t('assistant', 'Output shown here is generated by AI. Make sure to always double-check.') }}
 			</p>
@@ -186,6 +225,8 @@
 
 <script>
 import AutoFixIcon from 'vue-material-design-icons/AutoFix.vue'
+import ChevronDownIcon from 'vue-material-design-icons/ChevronDown.vue'
+import ChevronUpIcon from 'vue-material-design-icons/ChevronUp.vue'
 import PencilOutlineIcon from 'vue-material-design-icons/PencilOutline.vue'
 import PlusIcon from 'vue-material-design-icons/Plus.vue'
 import TrashCanOutlineIcon from 'vue-material-design-icons/TrashCanOutline.vue'
@@ -203,6 +244,7 @@ import NcAppNavigationList from '@nextcloud/vue/components/NcAppNavigationList'
 import NcAppNavigationNew from '@nextcloud/vue/components/NcAppNavigationNew'
 import NcButton from '@nextcloud/vue/components/NcButton'
 import NcLoadingIcon from '@nextcloud/vue/components/NcLoadingIcon'
+import NcTextField from '@nextcloud/vue/components/NcTextField'
 import NcDialog from '@nextcloud/vue/components/NcDialog'
 
 import ConversationBox from './ConversationBox.vue'
@@ -232,6 +274,8 @@ export default {
 	components: {
 		AgencyConfirmation,
 		AutoFixIcon,
+		ChevronDownIcon,
+		ChevronUpIcon,
 		TrashCanOutlineIcon,
 		PencilOutlineIcon,
 		PlusIcon,
@@ -249,6 +293,7 @@ export default {
 		NcAppNavigationNew,
 		NcButton,
 		NcLoadingIcon,
+		NcTextField,
 		NcDialog,
 
 		ConversationBox,
@@ -302,10 +347,56 @@ export default {
 					message: t('assisant', 'Which actions can you do for me?'),
 				},
 			],
+			searchQuery: '',
+			searchResults: { sessions: [] },
+			searchLoading: false,
+			searchDebounceTimer: null,
+			searchMatchIndex: 0,
+			highlightedMessageIndex: null,
 		}
 	},
 
 	computed: {
+		matchingMessageIndices() {
+			if (!this.messages?.length || !this.matchedMessageIds?.length) {
+				return []
+			}
+			return this.messages
+				.map((m, idx) => (this.matchedMessageIds.includes(m.id) ? idx : -1))
+				.filter((idx) => idx >= 0)
+		},
+		searchMatchNavVisible() {
+			return this.searchQuery.trim().length >= 2
+				&& this.matchingMessageIndices.length > 0
+				&& this.active != null
+				&& (this.messages?.length ?? 0) > 0
+		},
+		searchMatchCurrentDisplay() {
+			if (this.matchingMessageIndices.length === 0) {
+				return 0
+			}
+			const idx = Math.min(this.searchMatchIndex, this.matchingMessageIndices.length - 1)
+			return idx + 1
+		},
+		displayedSessions() {
+			if (this.sessions === null) {
+				return null
+			}
+			if (this.searchQuery.trim().length < 2) {
+				return this.sessions
+			}
+			return this.searchResults.sessions
+		},
+		matchedMessageIds() {
+			const q = this.searchQuery.trim()
+			if (q.length < 2 || !this.active || !this.messages?.length) {
+				return []
+			}
+			const lower = q.toLowerCase()
+			return this.messages
+				.filter((m) => m.content && m.content.toLowerCase().includes(lower))
+				.map((m) => m.id)
+		},
 		deletionConfirmationMessage() {
 			if (this.sessions === null || this.sessionIdToDelete === null) {
 				return ''
@@ -317,7 +408,19 @@ export default {
 	},
 
 	watch: {
+		matchingMessageIndices(indices) {
+			if (indices.length > 0) {
+				this.searchMatchIndex = indices.length - 1
+				const lastMessageIndex = indices[indices.length - 1]
+				this.$nextTick(() => {
+					this.scrollToMessageAndHighlight(lastMessageIndex)
+				})
+			} else {
+				this.searchMatchIndex = 0
+			}
+		},
 		async active() {
+			this.highlightedMessageIndex = null
 			this.allMessagesLoaded = false
 			this.loading.llmGeneration = false
 			this.loading.titleGeneration = false
@@ -432,15 +535,19 @@ export default {
 
 		async onEditSessionTitle(newTitle) {
 			this.loading.updateTitle = true
-			const session = this.sessions.find((session) => session.id === this.active.id)
+			const sessionId = this.active.id
 
 			try {
 				await axios.patch(getChatURL('/update_session'), {
-					sessionId: this.active.id,
+					sessionId,
 					title: newTitle,
 				})
 				this.editingTitle = false
-				session.title = newTitle
+				this.active.title = newTitle
+				const inSessions = this.sessions?.find((s) => s.id === sessionId)
+				if (inSessions) inSessions.title = newTitle
+				const inSearchResults = this.searchResults.sessions?.find((s) => s.id === sessionId)
+				if (inSearchResults) inSearchResults.title = newTitle
 			} catch (error) {
 				console.error('updateTitle error:', error)
 				showError(error?.response?.data?.error ?? t('assistant', 'Error updating title of conversation'))
@@ -565,6 +672,76 @@ export default {
 			}
 		},
 
+		onSearchInput(value) {
+			this.searchQuery = value
+			if (this.searchDebounceTimer) {
+				clearTimeout(this.searchDebounceTimer)
+			}
+			if (value.trim().length < 2) {
+				this.searchResults = { sessions: [] }
+				return
+			}
+			this.searchDebounceTimer = setTimeout(() => {
+				this.runSearch()
+			}, 300)
+		},
+
+		clearSearch() {
+			this.searchQuery = ''
+			this.searchResults = { sessions: [] }
+			this.highlightedMessageIndex = null
+			if (this.searchDebounceTimer) {
+				clearTimeout(this.searchDebounceTimer)
+				this.searchDebounceTimer = null
+			}
+		},
+		scrollToMessageAndHighlight(messageIndex) {
+			this.$nextTick(() => {
+				const el = this.$refs.chatArea?.querySelector(`#message${messageIndex}`)
+				if (el) {
+					el.scrollIntoView({ behavior: 'smooth', block: 'center' })
+				}
+				requestAnimationFrame(() => {
+					this.highlightedMessageIndex = messageIndex
+				})
+			})
+		},
+		goToPrevMatch() {
+			if (this.matchingMessageIndices.length === 0) {
+				return
+			}
+			this.searchMatchIndex = (this.searchMatchIndex - 1 + this.matchingMessageIndices.length) % this.matchingMessageIndices.length
+			const messageIndex = this.matchingMessageIndices[this.searchMatchIndex]
+			this.scrollToMessageAndHighlight(messageIndex)
+		},
+		goToNextMatch() {
+			if (this.matchingMessageIndices.length === 0) {
+				return
+			}
+			this.searchMatchIndex = (this.searchMatchIndex + 1) % this.matchingMessageIndices.length
+			const messageIndex = this.matchingMessageIndices[this.searchMatchIndex]
+			this.scrollToMessageAndHighlight(messageIndex)
+		},
+
+		async runSearch() {
+			const query = this.searchQuery.trim()
+			if (query.length < 2) {
+				this.searchResults = { sessions: [] }
+				return
+			}
+			try {
+				this.searchLoading = true
+				const response = await axios.get(getChatURL('/search'), { params: { query } })
+				this.searchResults = { sessions: response.data.sessions ?? [] }
+			} catch (error) {
+				console.error('searchChat error:', error)
+				this.searchResults = { sessions: [] }
+				showError(error?.response?.data?.error ?? t('assistant', 'Error searching conversations'))
+			} finally {
+				this.searchLoading = false
+			}
+		},
+
 		async fetchSessions() {
 			try {
 				const response = await axios.get(getChatURL('/sessions'))
@@ -690,6 +867,7 @@ export default {
 		},
 
 		async newSession(title = null) {
+			this.clearSearch()
 			try {
 				this.loading.newSession = true
 				const newSessionResponse = await axios.put(getChatURL('/new_session'), {
@@ -913,6 +1091,22 @@ export default {
 	display: flex;
 	height: 100%;
 
+	.chat-search {
+		display: flex;
+		align-items: center;
+		gap: 0.5em;
+		margin-bottom: 0.5em;
+
+		:deep(.input-field) {
+			flex: 1;
+			min-width: 0;
+		}
+
+		&__loading {
+			flex-shrink: 0;
+		}
+	}
+
 	:deep(.app-navigation-new) {
 		padding: 0;
 	}
@@ -1048,6 +1242,45 @@ export default {
 			}
 		}
 
+		&__search-match-nav {
+			display: flex;
+			align-items: center;
+			justify-content: center;
+			gap: 0.35em;
+			padding: 0.2em 0.4em 0.05em;
+			margin: 0 1em 0;
+			border-top: 1px solid var(--color-border);
+			color: var(--color-text-lighter);
+			font-weight: normal;
+			font-size: 0.9em;
+
+			&__label {
+				white-space: nowrap;
+			}
+
+			&__count {
+				min-width: 1.75em;
+				text-align: center;
+			}
+
+			&__arrows {
+				display: flex;
+				align-items: center;
+				gap: 4px;
+				border-left: 1px solid var(--color-border);
+				margin-left: 4px;
+				padding-left: 4px;
+			}
+
+			&__arrow {
+				:deep(button) {
+					padding: 2px 3px;
+					min-height: unset;
+					min-width: unset;
+				}
+			}
+		}
+
 		&__chat-area {
 			flex: 1;
 			display: flex;
@@ -1072,6 +1305,10 @@ export default {
 			margin: 0.5em 0;
 		}
 
+		&__search-match-nav + &__disclaimer {
+			margin-top: 0.15em;
+		}
+
 		&__agency-confirmation {
 			margin-left: 1em;
 		}
diff --git a/src/components/ChattyLLM/ConversationBox.vue b/src/components/ChattyLLM/ConversationBox.vue
index c73e0308..b0d1d5fd 100644
--- a/src/components/ChattyLLM/ConversationBox.vue
+++ b/src/components/ChattyLLM/ConversationBox.vue
@@ -29,8 +29,12 @@
 				:regenerate-loading="loading.llmGeneration && message.id === regenerateFromId"
 				:new-message-loading="loading.newHumanMessage && idx === (messages.length - 1)"
 				:information-source-names="informationSourceNames"
+				:search-query="searchQuery"
+				:is-search-match="matchedMessageIds && matchedMessageIds.includes(message.id)"
+				:highlighted="highlightedMessageIndex === idx"
 				@regenerate="regenerate(message.id)"
-				@delete="deleteMessage(message.id)" />
+				@delete="deleteMessage(message.id)"
+				@highlight-end="$emit('highlight-end')" />
 			<LoadingPlaceholder v-if="loading.llmGeneration" :slow-pickup="slowPickup" />
 		</div>
 	</div>
@@ -83,9 +87,21 @@ export default {
 			type: Boolean,
 			default: false,
 		},
+		searchQuery: {
+			type: String,
+			default: '',
+		},
+		matchedMessageIds: {
+			type: Array,
+			default: () => [],
+		},
+		highlightedMessageIndex: {
+			type: Number,
+			default: null,
+		},
 	},
 
-	emits: ['delete', 'regenerate'],
+	emits: ['delete', 'regenerate', 'highlight-end'],
 
 	data: () => {
 		return {
diff --git a/src/components/ChattyLLM/Message.vue b/src/components/ChattyLLM/Message.vue
index ff776294..130d2b04 100644
--- a/src/components/ChattyLLM/Message.vue
+++ b/src/components/ChattyLLM/Message.vue
@@ -5,8 +5,10 @@
 <template>
 	<div v-if="message.content || hasAttachments"
 		class="message"
+		:class="{ 'message--search-highlight': highlighted }"
 		@mouseover="showMessageActions = true"
-		@mouseleave="showMessageActions = false">
+		@mouseleave="showMessageActions = false"
+		@animationend="onAnimationEnd">
 		<MessageActions v-show="showMessageActions"
 			class="message__actions"
 			:show-regenerate="showRegenerate"
@@ -56,7 +58,7 @@
 			<NcDateTime class="message__header__timestamp" :timestamp="new Date((message?.timestamp ?? 0) * 1000)" :ignore-seconds="true" />
 		</div>
 		<NcRichText class="message__content"
-			:text="message.content"
+			:text="displayedContent"
 			:use-markdown="true"
 			:reference-limit="1"
 			:references="references"
@@ -139,9 +141,21 @@ export default {
 			type: Object,
 			default: null,
 		},
+		searchQuery: {
+			type: String,
+			default: '',
+		},
+		isSearchMatch: {
+			type: Boolean,
+			default: false,
+		},
+		highlighted: {
+			type: Boolean,
+			default: false,
+		},
 	},
 
-	emits: ['delete', 'regenerate'],
+	emits: ['delete', 'regenerate', 'highlight-end'],
 
 	data: () => {
 		return {
@@ -157,6 +171,15 @@ export default {
 	},
 
 	computed: {
+		displayedContent() {
+			if (!this.searchQuery.trim() || !this.isSearchMatch || !this.message.content) {
+				return this.message.content
+			}
+			const q = this.searchQuery.trim()
+			const escaped = q.replace(/[.*+?^${}()|[\]\\]/g, '\\$&')
+			const re = new RegExp(escaped, 'gi')
+			return this.message.content.replace(re, (match) => `*****${match}*****`)
+		},
 		parsedSources() {
 			if (!this.message.sources || ['', '[]'].includes(this.message.sources)) {
 				return []
@@ -178,6 +201,11 @@ export default {
 	},
 
 	methods: {
+		onAnimationEnd(e) {
+			if (e.animationName === 'searchHighlightFade') {
+				this.$emit('highlight-end')
+			}
+		},
 		copyMessage(message) {
 			navigator.clipboard.writeText(message)
 			showSuccess(t('assistant', 'Message copied to clipboard'))
@@ -217,6 +245,19 @@ export default {
 		background-color: var(--color-background-hover);
 	}
 
+	&--search-highlight {
+		animation: searchHighlightFade 1.2s ease-out;
+	}
+
+	@keyframes searchHighlightFade {
+		from {
+			background-color: var(--color-background-hover);
+		}
+		to {
+			background-color: transparent;
+		}
+	}
+
 	&__header {
 		display: flex;
 		flex-direction: row;
diff --git a/tests/unit/Controller/ChattyLLMControllerSearchTest.php b/tests/unit/Controller/ChattyLLMControllerSearchTest.php
new file mode 100644
index 00000000..8508959d
--- /dev/null
+++ b/tests/unit/Controller/ChattyLLMControllerSearchTest.php
@@ -0,0 +1,107 @@
+<?php
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Assistant\Tests\Unit\Controller;
+
+use OCA\Assistant\Controller\ChattyLLMController;
+use OCA\Assistant\Db\ChattyLLM\Session;
+use OCA\Assistant\Db\ChattyLLM\SessionMapper;
+use OCA\Assistant\Db\ChattyLLM\MessageMapper;
+use OCA\Assistant\Service\SessionSummaryService;
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\JSONResponse;
+use OCP\IAppConfig;
+use OCP\IL10N;
+use OCP\IRequest;
+use OCP\IUserManager;
+use OCP\TaskProcessing\IManager as ITaskProcessingManager;
+use PHPUnit\Framework\TestCase;
+use Psr\Log\LoggerInterface;
+
+class ChattyLLMControllerSearchTest extends TestCase {
+
+	public function testSearchChatWhenNotLoggedInReturnsUnauthorized(): void {
+		$controller = $this->createController(userId: null);
+		$response = $controller->searchChat('foo');
+		$this->assertInstanceOf(JSONResponse::class, $response);
+		$this->assertSame(Http::STATUS_UNAUTHORIZED, $response->getStatus());
+		$data = $response->getData();
+		$this->assertArrayHasKey('error', $data);
+	}
+
+	public function testSearchChatWithEmptyQueryReturnsEmptySessions(): void {
+		$controller = $this->createController(userId: 'user1');
+		$response = $controller->searchChat('');
+		$this->assertInstanceOf(JSONResponse::class, $response);
+		$this->assertSame(Http::STATUS_OK, $response->getStatus());
+		$this->assertSame(['sessions' => []], $response->getData());
+	}
+
+	public function testSearchChatWithShortQueryReturnsEmptySessions(): void {
+		$controller = $this->createController(userId: 'user1');
+		$response = $controller->searchChat('a');
+		$this->assertSame(Http::STATUS_OK, $response->getStatus());
+		$this->assertSame(['sessions' => []], $response->getData());
+	}
+
+	public function testSearchChatWithValidQueryReturnsSessionsFromMapper(): void {
+		$session = new Session();
+		$session->setId(1);
+		$session->setUserId('user1');
+		$session->setTitle('Test');
+		$session->setTimestamp(time());
+
+		$sessionMapper = $this->createMock(SessionMapper::class);
+		$sessionMapper->expects($this->once())
+			->method('searchSessionsByMessageContent')
+			->with('user1', 'hello')
+			->willReturn([$session]);
+
+		$controller = $this->createController(userId: 'user1', sessionMapper: $sessionMapper);
+		$response = $controller->searchChat('hello');
+		$this->assertSame(Http::STATUS_OK, $response->getStatus());
+		$data = $response->getData();
+		$this->assertArrayHasKey('sessions', $data);
+		$this->assertCount(1, $data['sessions']);
+		$this->assertSame(1, $data['sessions'][0]['id']);
+	}
+
+	public function testSearchChatWhenMapperThrowsReturnsInternalServerError(): void {
+		$sessionMapper = $this->createMock(SessionMapper::class);
+		$sessionMapper->method('searchSessionsByMessageContent')
+			->willThrowException(new \OCP\DB\Exception('DB error'));
+
+		$controller = $this->createController(userId: 'user1', sessionMapper: $sessionMapper);
+		$response = $controller->searchChat('hello');
+		$this->assertSame(Http::STATUS_INTERNAL_SERVER_ERROR, $response->getStatus());
+		$data = $response->getData();
+		$this->assertArrayHasKey('error', $data);
+	}
+
+	private function createController(
+		?string $userId = 'user1',
+		?SessionMapper $sessionMapper = null,
+	): ChattyLLMController {
+		$sessionMapper = $sessionMapper ?? $this->createMock(SessionMapper::class);
+		$l10n = $this->createMock(IL10N::class);
+		$l10n->method('t')->willReturnArgument(0);
+
+		return new ChattyLLMController(
+			'assistant',
+			$this->createMock(IRequest::class),
+			$sessionMapper,
+			$this->createMock(MessageMapper::class),
+			$l10n,
+			$this->createMock(LoggerInterface::class),
+			$this->createMock(ITaskProcessingManager::class),
+			$this->createMock(IAppConfig::class),
+			$this->createMock(IUserManager::class),
+			$userId,
+			$this->createMock(SessionSummaryService::class),
+		);
+	}
+}