diff --git a/third_party/astroglobe/lib/AppInfo/Application.php b/third_party/astroglobe/lib/AppInfo/Application.php
index 7e1ecfd..7889991 100644
--- a/third_party/astroglobe/lib/AppInfo/Application.php
+++ b/third_party/astroglobe/lib/AppInfo/Application.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace OCA\Astroglobe\AppInfo;
 
+use OCA\Astroglobe\Search\SemanticSearchProvider;
 use OCP\AppFramework\App;
 use OCP\AppFramework\Bootstrap\IBootContext;
 use OCP\AppFramework\Bootstrap\IBootstrap;
@@ -18,6 +19,8 @@ class Application extends App implements IBootstrap {
 	}
 
 	public function register(IRegistrationContext $context): void {
+		// Register unified search provider for semantic search
+		$context->registerSearchProvider(SemanticSearchProvider::class);
 	}
 
 	public function boot(IBootContext $context): void {
diff --git a/third_party/astroglobe/lib/Search/SemanticSearchProvider.php b/third_party/astroglobe/lib/Search/SemanticSearchProvider.php
new file mode 100644
index 0000000..bb3d753
--- /dev/null
+++ b/third_party/astroglobe/lib/Search/SemanticSearchProvider.php
@@ -0,0 +1,292 @@
+<?php
+
+declare(strict_types=1);
+
+namespace OCA\Astroglobe\Search;
+
+use OCA\Astroglobe\AppInfo\Application;
+use OCA\Astroglobe\Service\McpServerClient;
+use OCA\Astroglobe\Service\McpTokenStorage;
+use OCA\Astroglobe\Settings\Admin as AdminSettings;
+use OCP\IConfig;
+use OCP\IL10N;
+use OCP\IURLGenerator;
+use OCP\IUser;
+use OCP\Search\IProvider;
+use OCP\Search\ISearchQuery;
+use OCP\Search\SearchResult;
+use OCP\Search\SearchResultEntry;
+use Psr\Log\LoggerInterface;
+
+/**
+ * Unified Search provider for MCP Server semantic search.
+ *
+ * Delegates search queries to the MCP server's vector search API,
+ * returning semantically relevant results from indexed Nextcloud content
+ * (notes, files, calendar, deck cards).
+ *
+ * Security: Results are filtered server-side to only include documents
+ * owned by the searching user. User identity comes from OAuth token.
+ */
+class SemanticSearchProvider implements IProvider {
+	public function __construct(
+		private McpServerClient $client,
+		private McpTokenStorage $tokenStorage,
+		private IConfig $config,
+		private IL10N $l10n,
+		private IURLGenerator $urlGenerator,
+		private LoggerInterface $logger,
+	) {
+	}
+
+	/**
+	 * Unique identifier for this search provider.
+	 */
+	public function getId(): string {
+		return Application::APP_ID . '_semantic';
+	}
+
+	/**
+	 * Display name shown in search results grouping.
+	 */
+	public function getName(): string {
+		return $this->l10n->t('Astroglob');
+	}
+
+	/**
+	 * Order in search results. Lower = higher priority.
+	 * Use negative value when user is in our app's context.
+	 */
+	public function getOrder(string $route, array $routeParameters): int {
+		if (str_contains($route, Application::APP_ID)) {
+			return -1; // Prioritize when in Astroglobe app
+		}
+		return 40; // Above most apps, below files/mail
+	}
+
+	/**
+	 * Execute semantic search via MCP server.
+	 *
+	 * SECURITY: Results are filtered server-side to only include documents
+	 * owned by the searching user. User identity comes from OAuth token.
+	 */
+	public function search(IUser $user, ISearchQuery $query): SearchResult {
+		$term = $query->getTerm();
+		$limit = $query->getLimit();
+		$cursor = $query->getCursor();
+
+		// Skip empty queries
+		if (empty(trim($term))) {
+			return SearchResult::complete($this->getName(), []);
+		}
+
+		// Get OAuth token for user
+		$accessToken = $this->tokenStorage->getAccessToken($user->getUID());
+		if ($accessToken === null) {
+			// User hasn't authorized the app yet - return empty results
+			$this->logger->debug('No OAuth token for user in semantic search', [
+				'user_id' => $user->getUID(),
+			]);
+			return SearchResult::complete($this->getName(), []);
+		}
+
+		// Check if MCP server is available and vector sync enabled
+		$status = $this->client->getStatus();
+		if (!empty($status['error']) || !($status['vector_sync_enabled'] ?? false)) {
+			$this->logger->debug('MCP server not available or vector sync disabled', [
+				'status' => $status,
+			]);
+			return SearchResult::complete($this->getName(), []);
+		}
+
+		// Load admin search settings
+		$algorithm = $this->config->getAppValue(
+			Application::APP_ID,
+			AdminSettings::SETTING_SEARCH_ALGORITHM,
+			AdminSettings::DEFAULT_SEARCH_ALGORITHM
+		);
+		$fusion = $this->config->getAppValue(
+			Application::APP_ID,
+			AdminSettings::SETTING_SEARCH_FUSION,
+			AdminSettings::DEFAULT_SEARCH_FUSION
+		);
+		$scoreThreshold = (int)$this->config->getAppValue(
+			Application::APP_ID,
+			AdminSettings::SETTING_SEARCH_SCORE_THRESHOLD,
+			(string)AdminSettings::DEFAULT_SEARCH_SCORE_THRESHOLD
+		);
+		$configuredLimit = (int)$this->config->getAppValue(
+			Application::APP_ID,
+			AdminSettings::SETTING_SEARCH_LIMIT,
+			(string)AdminSettings::DEFAULT_SEARCH_LIMIT
+		);
+
+		// Use configured limit if query limit is higher
+		$effectiveLimit = min($limit, $configuredLimit);
+
+		// Calculate offset from cursor
+		$offset = $cursor ? (int)$cursor : 0;
+
+		// Execute semantic search with OAuth token and admin settings
+		// Server extracts user_id from token - results filtered to that user's documents
+		$results = $this->client->searchForUnifiedSearch(
+			query: $term,
+			token: $accessToken,
+			limit: $effectiveLimit,
+			offset: $offset,
+			algorithm: $algorithm,
+			fusion: $fusion,
+			scoreThreshold: $scoreThreshold / 100.0, // Convert percentage to 0-1 range
+		);
+
+		if (!empty($results['error'])) {
+			$this->logger->warning('Semantic search failed', [
+				'error' => $results['error'],
+				'query' => $term,
+			]);
+			return SearchResult::complete($this->getName(), []);
+		}
+
+		// Transform results to SearchResultEntry objects
+		$entries = [];
+		foreach ($results['results'] ?? [] as $result) {
+			$entries[] = $this->transformResult($result);
+		}
+
+		// Return paginated if more results might exist
+		$totalFound = $results['total_found'] ?? count($entries);
+		if (count($entries) >= $effectiveLimit && $totalFound > $offset + $effectiveLimit) {
+			return SearchResult::paginated(
+				$this->getName(),
+				$entries,
+				(string)($offset + $effectiveLimit)
+			);
+		}
+
+		return SearchResult::complete($this->getName(), $entries);
+	}
+
+	/**
+	 * Transform MCP search result to Nextcloud SearchResultEntry.
+	 */
+	private function transformResult(array $result): SearchResultEntry {
+		$docType = $result['doc_type'] ?? 'unknown';
+		$title = $result['title'] ?? $this->l10n->t('Untitled');
+		$excerpt = $result['excerpt'] ?? '';
+		$score = $result['score'] ?? 0;
+
+		// Build resource URL based on document type
+		$resourceUrl = $this->buildResourceUrl($result);
+
+		// Build thumbnail URL based on document type
+		$thumbnailUrl = $this->buildThumbnailUrl($docType);
+
+		// Subline shows full excerpt if available, otherwise document type and score
+		if (!empty($excerpt)) {
+			// Show full chunk content - no truncation
+			$subline = $excerpt;
+		} else {
+			$subline = sprintf(
+				'%s · %d%% %s',
+				$this->getDocTypeLabel($docType),
+				(int)($score * 100),
+				$this->l10n->t('relevant')
+			);
+		}
+
+		return new SearchResultEntry(
+			$thumbnailUrl,
+			$title,
+			$subline,
+			$resourceUrl,
+			'', // icon class (empty, using thumbnail)
+			false // not rounded
+		);
+	}
+
+	/**
+	 * Build URL to navigate to the original document.
+	 *
+	 * URL formats match App.vue's getDocumentUrl() implementation for consistency.
+	 */
+	private function buildResourceUrl(array $result): string {
+		$docType = $result['doc_type'] ?? 'unknown';
+		$id = $result['id'] ?? null;
+		$path = $result['path'] ?? null;
+
+		return match ($docType) {
+			'note' => $id
+				? $this->urlGenerator->linkToRoute('notes.page.index') . '/#/note/' . $id
+				: $this->urlGenerator->linkToRoute('notes.page.index'),
+
+			'file' => $id
+				? $this->urlGenerator->linkToRouteAbsolute('files.view.index') . '/' . $id . '?openfile=true'
+				: $this->urlGenerator->linkToRouteAbsolute('files.view.index'),
+
+			'deck_card' => isset($result['board_id'], $result['card_id'])
+				? $this->urlGenerator->linkToRoute('deck.page.index') .
+				  "/#!/board/{$result['board_id']}/card/{$result['card_id']}"
+				: $this->urlGenerator->linkToRoute('deck.page.index'),
+
+			'calendar', 'calendar_event' => $this->urlGenerator->linkToRoute('calendar.view.index'),
+
+			'news_item' => $this->urlGenerator->linkToRoute('news.page.index'),
+
+			'contact' => $this->urlGenerator->linkToRoute('contacts.page.index'),
+
+			default => $this->urlGenerator->linkToRoute(Application::APP_ID . '.page.index'),
+		};
+	}
+
+	/**
+	 * Get thumbnail URL for document type.
+	 */
+	private function buildThumbnailUrl(string $docType): string {
+		// Use app icons for different document types
+		return match ($docType) {
+			'note' => $this->urlGenerator->imagePath('notes', 'app.svg'),
+			'file' => $this->urlGenerator->imagePath('files', 'app.svg'),
+			'deck_card' => $this->urlGenerator->imagePath('deck', 'app.svg'),
+			'calendar', 'calendar_event' => $this->urlGenerator->imagePath('calendar', 'app.svg'),
+			'news_item' => $this->urlGenerator->imagePath('news', 'app.svg'),
+			'contact' => $this->urlGenerator->imagePath('contacts', 'app.svg'),
+			default => $this->urlGenerator->imagePath(Application::APP_ID, 'app.svg'),
+		};
+	}
+
+	/**
+	 * Get human-readable label for document type.
+	 */
+	private function getDocTypeLabel(string $docType): string {
+		return match ($docType) {
+			'note' => $this->l10n->t('Note'),
+			'file' => $this->l10n->t('File'),
+			'deck_card' => $this->l10n->t('Deck Card'),
+			'calendar', 'calendar_event' => $this->l10n->t('Calendar'),
+			'news_item' => $this->l10n->t('News'),
+			'contact' => $this->l10n->t('Contact'),
+			default => $this->l10n->t('Document'),
+		};
+	}
+
+	/**
+	 * Truncate excerpt to a maximum length, breaking at word boundaries.
+	 */
+	private function truncateExcerpt(string $excerpt, int $maxLength): string {
+		$excerpt = trim($excerpt);
+
+		if (mb_strlen($excerpt) <= $maxLength) {
+			return $excerpt;
+		}
+
+		// Find last space before limit
+		$truncated = mb_substr($excerpt, 0, $maxLength);
+		$lastSpace = mb_strrpos($truncated, ' ');
+
+		if ($lastSpace !== false && $lastSpace > $maxLength * 0.7) {
+			$truncated = mb_substr($truncated, 0, $lastSpace);
+		}
+
+		return $truncated . '…';
+	}
+}