diff --git a/DocumentOperator.Application/Common/Interfaces/IPdfProcessor.cs b/DocumentOperator.Application/Common/Interfaces/IPdfProcessor.cs
index 9c7795c..87b4a78 100644
--- a/DocumentOperator.Application/Common/Interfaces/IPdfProcessor.cs
+++ b/DocumentOperator.Application/Common/Interfaces/IPdfProcessor.cs
@@ -7,30 +7,39 @@ public interface IPdfProcessor
     /// <summary>
     /// Validates a PDF and extracts metadata.
     /// </summary>
-    /// <param name="pdfStream">PDF content as stream (caller is responsible for disposal)</param>
+    /// <param name="pdfStream">
+    /// PDF document stream. Must be readable and positioned at the beginning (Position = 0).
+    /// Non-seekable streams are supported. Caller is responsible for disposal.
+    /// </param>
     /// <returns>PDF metadata (page count, size, version, attachments)</returns>
     /// <exception cref="Domain.Common.Exceptions.BadRequestException">
-    /// Thrown when stream is empty or invalid
+    /// Thrown when stream is empty, invalid, or not positioned at the beginning
     /// </exception>
     Task<PdfMetadata> ValidateAsync(Stream pdfStream);
 
     /// <summary>
     /// Validates a PDF/A document and checks conformance level.
     /// </summary>
-    /// <param name="pdfStream">PDF content as stream (caller is responsible for disposal)</param>
+    /// <param name="pdfStream">
+    /// PDF document stream. Must be readable and positioned at the beginning (Position = 0).
+    /// Non-seekable streams are supported. Caller is responsible for disposal.
+    /// </param>
     /// <returns>PDF/A metadata including conformance level and validation errors/warnings</returns>
     /// <exception cref="Domain.Common.Exceptions.BadRequestException">
-    /// Thrown when stream is empty or invalid
+    /// Thrown when stream is empty, invalid, or not positioned at the beginning
     /// </exception>
     Task<PdfAMetadata> ValidatePdfAAsync(Stream pdfStream);
 
     /// <summary>
     /// Checks for embedded files (attachments) in a PDF document and returns detailed metadata.
     /// </summary>
-    /// <param name="pdfStream">PDF content as stream (caller is responsible for disposal)</param>
+    /// <param name="pdfStream">
+    /// PDF document stream. Must be readable and positioned at the beginning (Position = 0).
+    /// Non-seekable streams are supported. Caller is responsible for disposal.
+    /// </param>
     /// <returns>Attachment information (count, file names, MIME types, sizes)</returns>
     /// <exception cref="Domain.Common.Exceptions.BadRequestException">
-    /// Thrown when stream is empty or invalid
+    /// Thrown when stream is empty, invalid, or not positioned at the beginning
     /// </exception>
     Task<AttachmentInfo> CheckAttachmentsAsync(Stream pdfStream);
 }
\ No newline at end of file
diff --git a/DocumentOperator.Application/Common/Interfaces/ISwissQrCodeProcessor.cs b/DocumentOperator.Application/Common/Interfaces/ISwissQrCodeProcessor.cs
index baa746a..3d95887 100644
--- a/DocumentOperator.Application/Common/Interfaces/ISwissQrCodeProcessor.cs
+++ b/DocumentOperator.Application/Common/Interfaces/ISwissQrCodeProcessor.cs
@@ -12,18 +12,21 @@ public interface ISwissQrCodeProcessor
     /// Extracts and parses Swiss QR Code from a PDF document.
     /// Returns both parsed Bill object and raw QR text lines.
     /// </summary>
-    /// <param name="pdfBytes">PDF document as byte array</param>
+    /// <param name="pdfStream">
+    /// PDF document stream. Must be readable and positioned at the beginning (Position = 0).
+    /// Non-seekable streams are supported. Caller is responsible for disposal.
+    /// </param>
     /// <param name="pageNumbers">Optional: Specific page numbers to scan (1-indexed). If null, scans all pages starting with last page.</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>Tuple: (Parsed Codecrete Bill, Raw QR lines as string array)</returns>
-    /// <exception cref="Domain.Exceptions.SwissQrCodeNotFoundException">
+    /// <exception cref="Domain.Common.Exceptions.NotFoundException">
     /// Thrown when no Swiss QR Code is found in the specified pages
     /// </exception>
-    /// <exception cref="Domain.Exceptions.PdfProcessingException">
-    /// Thrown when PDF processing fails
+    /// <exception cref="ArgumentException">
+    /// Thrown when stream is empty or (for seekable streams) not positioned at the beginning
     /// </exception>
     Task<(Bill Bill, string[] RawLines)> ExtractSwissQrCodeAsync(
-        byte[] pdfBytes, 
+        Stream pdfStream, 
         int[]? pageNumbers = null, 
         CancellationToken cancellationToken = default);
 }