feat: complete task 6 - fix stale notification pruning to avoid SQLite parameter limit

internal/musicbrainz/sync.go

@@ -113,7 +113,7 @@ func SyncArtistDiscography(
 
 	// Build the set of RGIDs present in this sync so we can drop only the rows
 	// that disappeared, leaving the rest (and their notification markers) intact.
-	synced := make([]any, 0, len(filtered))
+	synced := make([]string, 0, len(filtered))
 	for _, rg := range filtered {
 		synced = append(synced, rg.ID)
 	}
@@ -121,24 +121,55 @@ func SyncArtistDiscography(
 	// Drop notification markers for releases that are gone. This runs before the
 	// external_releases delete so the FK on notifications_sent.rgid stays valid
 	// (we only ever delete from notifications_sent here).
+	// Process in chunks to avoid SQLite parameter limits (default limit is 999).
 	if len(synced) > 0 {
-		placeholders := strings.Repeat("?,", len(synced))
-		placeholders = placeholders[:len(placeholders)-1]
-		query := fmt.Sprintf(
-			"DELETE FROM notifications_sent WHERE rgid IN (SELECT rgid FROM external_releases WHERE artist_id = ? AND rgid NOT IN (%s))",
-			placeholders,
-		)
-		args := append([]any{artistID}, synced...)
-		if _, err := tx.Exec(query, args...); err != nil {
-			return nil, fmt.Errorf("sync artist discography: prune stale notifications: %w", err)
+		const chunkSize = 500
+		for i := 0; i < len(synced); i += chunkSize {
+			end := i + chunkSize
+			if end > len(synced) {
+				end = len(synced)
+			}
+			chunk := synced[i:end]
+
+			placeholders := strings.Repeat("?,", len(chunk))
+			placeholders = placeholders[:len(placeholders)-1]
+			query := fmt.Sprintf(
+				"DELETE FROM notifications_sent WHERE rgid IN (SELECT rgid FROM external_releases WHERE artist_id = ? AND rgid NOT IN (%s))",
+				placeholders,
+			)
+			args := make([]any, 1+len(chunk))
+			args[0] = artistID
+			for i, v := range chunk {
+				args[i+1] = v
+			}
+			if _, err := tx.Exec(query, args...); err != nil {
+				return nil, fmt.Errorf("sync artist discography: prune stale notifications (chunk %d-%d): %w", i, end, err)
+			}
 		}
+
 		// Remove external_release rows that are no longer part of the discography.
-		delQuery := fmt.Sprintf(
-			"DELETE FROM external_releases WHERE artist_id = ? AND rgid NOT IN (%s)",
-			placeholders,
-		)
-		if _, err := tx.Exec(delQuery, args...); err != nil {
-			return nil, fmt.Errorf("sync artist discography: delete stale releases: %w", err)
+		// Process in chunks to avoid SQLite parameter limits.
+		for i := 0; i < len(synced); i += chunkSize {
+			end := i + chunkSize
+			if end > len(synced) {
+				end = len(synced)
+			}
+			chunk := synced[i:end]
+
+			placeholders := strings.Repeat("?,", len(chunk))
+			placeholders = placeholders[:len(placeholders)-1]
+			delQuery := fmt.Sprintf(
+				"DELETE FROM external_releases WHERE artist_id = ? AND rgid NOT IN (%s)",
+				placeholders,
+			)
+			args := make([]any, 1+len(chunk))
+			args[0] = artistID
+			for i, v := range chunk {
+				args[i+1] = v
+			}
+			if _, err := tx.Exec(delQuery, args...); err != nil {
+				return nil, fmt.Errorf("sync artist discography: delete stale releases (chunk %d-%d): %w", i, end, err)
+			}
 		}
 	} else {
 		// No releases this sync: the artist may have an empty discography. Drop