✨ Complete multi-document mode

internal/services/document_service.go

@@ -3,6 +3,7 @@ package services
 import (
 	"context"
 	"database/sql"
+	"errors"
 	"fmt"
 	"path/filepath"
 	"sync"
@@ -191,7 +192,7 @@ func (ds *DocumentService) GetDocumentByID(id int64) (*models.Document, error) {
 	row := ds.db.QueryRow(sqlGetDocumentByID, id)
 	err := row.Scan(&doc.ID, &doc.Title, &doc.Content, &doc.CreatedAt, &doc.UpdatedAt)
 	if err != nil {
-		if err == sql.ErrNoRows {
+		if errors.Is(err, sql.ErrNoRows) {
 			return nil, nil
 		}
 		return nil, fmt.Errorf("failed to get document by ID: %w", err)