perf(mana/web): index updatedAt for recent-X dashboard widgets

Schema bump V9 adds an updatedAt secondary index to the six tables
that the cross-app dashboard widgets use for "recent N" lookups:
conversations, images, presiDecks, documents, songs, mukkePlaylists.
Dexie builds the index lazily on first open — no migration code,
no data touched.

Recent-query refactor:
  useRecentConversations
  useRecentImages
  useRecentDecks
  useRecentDocuments

  All four switched from `toArray() + JS sort + slice` to
  `orderBy('updatedAt').reverse().filter().limit()`. Dexie walks the
  BTree backwards and short-circuits as soon as `limit` matches
  accumulate, so the cost is O(limit + filtered) instead of O(table).

  For a dashboard with thousands of stored conversations or images,
  the dashboard widget previously read every record on every render
  (liveQuery re-runs on any write). Now it stops after 5–6 hits.

Verified: 20/20 sync.test.ts still passing.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/mana/apps/web/src/lib/data/cross-app-queries.ts

@@ -117,11 +117,18 @@ export function useFavoriteContacts(limit = 5) {
 /** Recent conversations, sorted by updatedAt desc. */
 export function useRecentConversations(limit = 5) {
 	return useLiveQueryWithDefault(async () => {
-		const all = await db.table<LocalConversation>('conversations').toArray();
-		return all
+		// Walk the indexed updatedAt BTree in reverse, filtering archived /
+		// soft-deleted entries on the fly. Dexie's `.limit()` short-circuits
+		// the iterator as soon as that many matches accumulate, so the cost
+		// is O(limit + filtered) instead of the O(table) toArray+sort the
+		// query used to do.
+		return db
+			.table<LocalConversation>('conversations')
+			.orderBy('updatedAt')
+			.reverse()
 			.filter((c) => !c.isArchived && !c.deletedAt)
-			.sort((a, b) => (b.updatedAt ?? '').localeCompare(a.updatedAt ?? ''))
-			.slice(0, limit);
+			.limit(limit)
+			.toArray();
 	}, [] as LocalConversation[]);
 }
 
@@ -145,11 +152,16 @@ export function useRandomFavorite() {
 /** Recent generated images. */
 export function useRecentImages(limit = 6) {
 	return useLiveQueryWithDefault(async () => {
-		const all = await db.table<LocalImage>('images').toArray();
-		return all
+		// Reverse-walk the indexed updatedAt column. Generated images have
+		// updatedAt stamped on creation and rarely move afterwards, so this
+		// is effectively "newest first" for the dashboard widget's purpose.
+		return db
+			.table<LocalImage>('images')
+			.orderBy('updatedAt')
+			.reverse()
 			.filter((i) => !i.isArchived && !i.deletedAt)
-			.sort((a, b) => (b.createdAt ?? '').localeCompare(a.createdAt ?? ''))
-			.slice(0, limit);
+			.limit(limit)
+			.toArray();
 	}, [] as LocalImage[]);
 }
 
@@ -231,11 +243,13 @@ export function useMusicStats() {
 /** Recent presentation decks. */
 export function useRecentDecks(limit = 5) {
 	return useLiveQueryWithDefault(async () => {
-		const all = await db.table<LocalPresiDeck>('presiDecks').toArray();
-		return all
+		return db
+			.table<LocalPresiDeck>('presiDecks')
+			.orderBy('updatedAt')
+			.reverse()
 			.filter((d) => !d.deletedAt)
-			.sort((a, b) => (b.updatedAt ?? '').localeCompare(a.updatedAt ?? ''))
-			.slice(0, limit);
+			.limit(limit)
+			.toArray();
 	}, [] as LocalPresiDeck[]);
 }
 
@@ -244,11 +258,13 @@ export function useRecentDecks(limit = 5) {
 /** Recent documents + spaces. */
 export function useRecentDocuments(limit = 5) {
 	return useLiveQueryWithDefault(async () => {
-		const all = await db.table<LocalDocument>('documents').toArray();
-		return all
+		return db
+			.table<LocalDocument>('documents')
+			.orderBy('updatedAt')
+			.reverse()
 			.filter((d) => !d.deletedAt)
-			.sort((a, b) => (b.updatedAt ?? '').localeCompare(a.updatedAt ?? ''))
-			.slice(0, limit);
+			.limit(limit)
+			.toArray();
 	}, [] as LocalDocument[]);
 }
 

apps/mana/apps/web/src/lib/data/database.ts

@@ -442,6 +442,30 @@ db.version(8).stores({
 	_eventsTombstones: 'id, token, attempts, createdAt',
 });
 
+// ─── Version 9: Add updatedAt indexes for "recent X" dashboard widgets ─
+//
+// Several cross-app queries (`useRecentConversations`, `useRecentImages`,
+// `useRecentDecks`, `useRecentDocuments`) used to load entire tables and
+// JS-sort by `updatedAt`. With these indexes Dexie can walk the BTree in
+// reverse and stop after N matches.
+//
+// `++` is NOT used — we are only adding secondary indexes to existing
+// stores. The full `stores()` line is repeated because Dexie's upgrade
+// API requires the complete schema for the version, even when most
+// fields are unchanged.
+//
+// No data migration needed: indexes are built lazily by Dexie at upgrade
+// time without touching record contents.
+
+db.version(9).stores({
+	conversations: 'id, isArchived, isPinned, spaceId, templateId, updatedAt',
+	images: 'id, isFavorite, isPublic, isArchived, prompt, updatedAt',
+	presiDecks: 'id, isPublic, updatedAt',
+	documents: 'id, spaceId, type, pinned, title, [spaceId+type], updatedAt',
+	songs: 'id, artist, album, genre, favorite, title, updatedAt',
+	mukkePlaylists: 'id, name, updatedAt',
+});
+
 // ─── Sync App Map ──────────────────────────────────────────
 // Maps each table to its appId for sync routing.
 // The SyncEngine uses this to group pending changes and push to /sync/{appId}.