chore: Add DocumentService.Client project reference to Tests

Introduced multiple interfaces and DTOs to support a wide range of
PDF-related operations, including attachment handling, conversion,
validation, annotation, stamping, and metadata extraction.

Key changes:
- Added `DocumentServiceClientOptions` for HTTP client config.
- Introduced `IPdfAttachmentClient` for attachment operations.
- Added `IPdfConversionClient` for PDF/A conversion (marked obsolete).
- Added `IPdfOperationsClient` for merge, annotate, and stamp ops.
- Introduced `IPdfValidationClient` for PDF and PDF/A validation.
- Added `ISwissQrCodeClient` for Swiss QR Code extraction.
- Added `IZugferdClient` for ZUGFeRD detection and extraction.
- Created request DTOs for Base64-encoded operations.
- Added enums for annotation, stamp, and validation configurations.

These changes provide a flexible and extensible foundation for
interacting with PDF documents, supporting both multipart and
Base64-encoded inputs, and ensuring type safety with enums and records.

AGENTS.md

@@ -1,6 +1,6 @@
 # AGENTS.md
 
-Agent guidance for DocumentOperator service. Read this before working on the codebase.
+Agent guidance for DocumentService service. Read this before working on the codebase.
 
 ---
 
@@ -23,7 +23,7 @@ Agent guidance for DocumentOperator service. Read this before working on the cod
 ### Migration Required
 
 **Existing code that needs replacement:**
-- `DocumentOperator.API/Endpoints/v1/DocumentEndpoints.cs` → Delete, replace with Controllers
+- `DocumentService.API/Endpoints/v1/DocumentEndpoints.cs` → Delete, replace with Controllers
 - `Program.cs` line 72: `app.MapDocumentEndpoints()` → Replace with `app.MapControllers()`
 - `Program.cs` line 44: Add `builder.Services.AddControllers()`
 - All DTOs → Support **BOTH** `IFormFile` (multipart) AND `Base64String` (JSON)
@@ -177,7 +177,7 @@ All files for a feature live together. Do NOT create separate Commands/, Handler
 - ✅ All features currently work without authentication
 
 **When to implement:**
-After completing all Phase 1-3 controllers (PdfValidation, PdfAttachment, PdfOperations, PdfRender, PdfConversion), then add multi-tenancy to ALL endpoints in one refactoring phase.
+After completing all Phase 1-3 controllers (PdfValidation, PdfAttachment, SwissQrCode, PdfOperations, PdfConversion), then add multi-tenancy to ALL endpoints in one refactoring phase.
 
 ---
 
@@ -188,16 +188,17 @@ After completing all Phase 1-3 controllers (PdfValidation, PdfAttachment, PdfOpe
 dotnet build
 ```
 
-**Run tests (19 tests as of Feature 2):**
+**Run tests (101 passed, 7 skipped as of Feature 7 - PDF Stamp):**
 ```powershell
 dotnet test
 ```
 
 **Run API (Development):**
 ```powershell
-dotnet run --project DocumentOperator.API
+dotnet run --project DocumentService.API
 ```
-Swagger UI: `https://localhost:<port>/swagger`
+Swagger UI: `https://localhost:7186/swagger`  
+Serilog UI: `https://localhost:7186/serilog-ui` (Web-based log viewer)
 
 **Target framework:** .NET 8.0  
 **SDK required:** 8.0.412 or later (repo has 8.0.412–10.0.203 available)
@@ -214,6 +215,8 @@ Swagger UI: `https://localhost:<port>/swagger`
 | **MediatR** (14.1.0) | CQRS: 1 handler per feature | Application layer |
 | **FluentValidation** (12.1.1) | Request validation (runs via ValidationBehavior before handlers) | Application layer |
 | **Serilog.AspNetCore** (10.0.0) | Structured logging | API layer |
+| **Serilog.Sinks.SQLite** (7.0.0) | SQLite log persistence | API layer |
+| **Serilog.UI** (3.2.0) + **Serilog.UI.SqliteProvider** (1.1.0) | Web-based log viewer UI | API layer |
 
 **Critical:** DevExpress requires a license. All PDF operations use `DevExpress.Pdf.PdfDocumentProcessor`.
 
@@ -245,30 +248,51 @@ Do NOT add `if (result.IsSuccess)` checks. Throw exceptions for errors. The midd
 1. `PdfValidationController` – 2 endpoints
    - `POST /api/pdf/validation/validate` (Basic PDF validation)
    - `POST /api/pdf/validation/validate-pdfa` (PDF/A conformance)
-2. `PdfAttachmentController` – 2 endpoints
+2. `PdfAttachmentController` – check endpoint
    - `POST /api/pdf/attachments/check` (Attachment detection)
-   - `POST /api/pdf/attachments/extract` (Extract attachments)
-3. `PdfOperationsController` – Merge endpoint
+3. `SwissQrCodeController` – extract endpoint
+   - `POST /api/swissqrcode/extract` (Swiss QR Bill extraction)
+4. `PdfAttachmentController` – extract endpoint
+   - `POST /api/pdf/attachments/extract` (Extract attachments as ZIP)
+5. `PdfOperationsController` – merge endpoint
    - `POST /api/pdf/operations/merge` (Merge multiple PDFs)
 
 **Phase 2:**
-4. `PdfOperationsController` – Stamp & Annotate
-5. `PdfRenderController` – Preview
+6. `PdfOperationsController` – stamp & annotate
+   - `POST /api/pdf/operations/stamp` (Add stamps)
+   - `POST /api/pdf/operations/annotate` (Add annotations)
+7. `PdfAttachmentController` – add attachment
+   - `POST /api/pdf/attachments/add` (Embed attachments in PDF/A-3)
 
 **Phase 3:**
-6. `PdfConversionController` – PDF ↔ PDF/A conversion
+8. `PdfConversionController` – PDF ↔ PDF/A conversion
+   - `POST /api/pdf/conversion/to-pdfa` (Convert to PDF/A)
+   - `POST /api/pdf/conversion/from-pdfa` (Convert from PDF/A)
+
+**Removed:**
+- `PdfRenderController` – Moved to .NET client library (WinForms/WPF DevExpress controls)
 
 ### Current Status
 
 | Controller | Status | Tests |
 |-----------|--------|-------|
-| **PdfValidationController** | ⏳ Pending | 0 |
-| **PdfAttachmentController** | ⏳ Pending | 0 |
-| **PdfOperationsController** | ⏳ Pending | 0 |
-| **PdfRenderController** | ⏳ Pending | 0 |
+| **PdfValidationController** | ✅ DONE | 13 (7 validate + 6 validate-pdfa) |
+| **SwissQrCodeController** | ✅ DONE | 2 |
+| **PdfAttachmentController** | ⏳ Partial (2/3 endpoints) | 10 (4 check + 6 extract) |
+| **PdfOperationsController** | ⏳ Partial (3/3 endpoints, integration tests pending) | 29 (7 merge + 22 annotate: 12 unit + 10 integration) |
 | **PdfConversionController** | ⏳ Pending | 0 |
 
-**Legacy code exists** (`DocumentEndpoints.cs` with Minimal API + Base64 JSON), but **must be replaced** with Controllers + multipart/form-data.
+**PdfAttachmentController Status:**
+- ✅ `POST /api/pdf/attachments/check` - DONE (with multipart + Base64 support)
+- ✅ `POST /api/pdf/attachments/extract` - DONE (Phase 1, Priority 4) - Returns ZIP with all attachments
+- ⏳ `POST /api/pdf/attachments/add` - TODO (Phase 2, Priority 7)
+
+**PdfOperationsController Status:**
+- ✅ `POST /api/pdf/operations/merge` - DONE (Phase 1, Priority 5) - Merges multiple PDFs with optional page ranges (multipart + Base64)
+- ✅ `POST /api/pdf/operations/annotate` - DONE (Phase 2, Priority 6) - Adds annotations (TextMarkup/FreeText/StickyNote/Circle/Square) with multipart + Base64 support
+- ✅ `POST /api/pdf/operations/stamp` - DONE (Phase 2, Priority 6) - Adds text/image/predefined stamps (multipart + Base64 support, origin/rotation/opacity/placement)
+
+**Note:** PdfRenderController removed - moved to .NET client library.
 
 ---
 
@@ -315,13 +339,77 @@ Do NOT skip steps. Each feature is done when it's **testable in Swagger UI with
 **All test PDFs are EmbeddedResource.** Access via:
 ```csharp
 var stream = Assembly.GetExecutingAssembly()
-    .GetManifestResourceStream("DocumentOperator.Tests.TestData.Pdfs.valid.pdf");
+    .GetManifestResourceStream("DocumentService.Tests.TestData.Pdfs.valid.pdf");
 ```
 
 **Do NOT commit new binary files** without marking them as `<EmbeddedResource>`.
 
 ---
 
+## Test Structure & Strategy
+
+**3-folder structure (CORRECT approach by previous developer):**
+
+```
+DocumentService.Tests/
+├── Integration/
+│   └── API/
+│       ├── PdfValidationControllerTests.cs (13 tests)
+│       └── ExtractSwissQrCodeEndpointTests.cs (2 tests)
+├── TestData/
+│   └── Pdfs/ (EmbeddedResource PDFs)
+├── Unit/
+│   ├── Application/
+│   │   └── Features/
+│   │       ├── ValidatePdf/
+│   │       │   └── ValidatePdfHandlerTests.cs (2 tests)
+│   │       ├── ValidatePdfA/
+│   │       │   └── ValidatePdfAQueryHandlerTests.cs (4 tests)
+│   │       └── ExtractSwissQrCode/
+│   │           └── ExtractSwissQrCodeHandlerTests.cs (2 tests)
+│   └── Infrastructure/
+│       └── Services/
+│           └── PdfProcessing/
+│               └── DevExpressPdfProcessorTests.cs (7 tests)
+```
+
+**✅ Why this structure is CORRECT:**
+
+1. **Integration vs Unit separation:**
+   - **Integration:** WebApplicationFactory → REAL API calls (HTTP, middleware, MediatR pipeline, DevExpress)
+   - **Unit:** Mock-based ISOLATED tests (Handler only depends on mocked IPdfProcessor)
+
+2. **TestData centralization:**
+   - All 3 layers share same EmbeddedResource PDFs (no duplication)
+   - Accessed via `Assembly.GetManifestResourceStream()`
+
+3. **Vertical Slice compliance:**
+   - `Unit/Application/Features/ValidatePdf/` → Each feature's tests co-located
+   - Matches Application layer structure exactly
+
+4. **Test Pyramid:**
+   - **Unit tests (60+):** Fast, isolated, many scenarios
+   - **Integration tests (27):** Slower, full pipeline, critical paths only
+
+**Test count:** 101 passed, 7 skipped (as of Feature 6 - PDF Annotation)
+
+**Test breakdown by feature:**
+- Feature 1 (PDF Validation): 13 integration tests
+- Feature 2 (Swiss QR Code): 2 integration tests  
+- Feature 3 (PDF/A Validation): 6 integration tests (validate-pdfa) + 4 unit tests (handler)
+- Feature 4 (PDF Attachments): 10 tests (4 check + 6 extract integration)
+- Feature 5 (PDF Merge): 7 integration + 10 unit tests (DevExpressPdfProcessor)
+- Feature 6 (PDF Annotation): 10 integration + 12 unit tests (DevExpressPdfProcessor)
+- Infrastructure: 37 unit tests (DevExpressPdfProcessor for validation, attachments, merge, annotation)
+
+**FluentValidation in tests:**
+- Base64 format validation happens in `ValidatePdfQueryValidator` and `ValidatePdfAQueryValidator`
+- Prevents `FormatException` from reaching handler (caught as 400 Bad Request, not 500)
+- Unit tests verify handler behavior with valid inputs only
+- Integration tests verify full validation pipeline (including FluentValidation)
+
+---
+
 ## Swiss QR Code Feature (Feature 2)
 
 **Swiss QR Bill Standard 2.0** requires:
@@ -432,7 +520,7 @@ public async Task<IActionResult> Validate([FromForm] PdfInputModel input, Cancel
 ## Configuration
 
 **appsettings.json sections:**
-- `DocumentOperatorSettings` (future: file size limits, temp paths)
+- `DocumentServiceSettings` (future: file size limits, temp paths)
 - `RedisSettings` (future: multi-tenancy caching)
 - `ApiKeySettings` (future: authentication)
 

CONTROLLER_ENDPOINTS.md

@@ -1,4 +1,4 @@
-# DocumentOperator - Controller & Endpoint Specification
+# DocumentService - Controller & Endpoint Specification
 
 **Project:** DocumentService (DOC)  
 **Ticket:** DOC-1 - GDPicture and Nutrient Replacing  
@@ -9,7 +9,7 @@
 
 ## Overview
 
-This specification defines the controller structure and REST API endpoints for the DocumentOperator service.
+This specification defines the controller structure and REST API endpoints for the DocumentService service.
 
 ---
 
@@ -90,34 +90,37 @@ This specification defines the controller structure and REST API endpoints for t
 
 ### Endpoint: Attachment Extraction
 **Route:** `POST /api/pdf/attachments/extract`  
-**Function:** Extracts all embedded files from the PDF and saves them to the specified path
+**Function:** Extracts all embedded files from the PDF and returns them as a ZIP archive
 
 **Input:**
-```json
-{
-  "file": "PDF (multipart/form-data)",
-  "outputPath": string
-}
-```
+- PDF file (multipart/form-data)
 
 **Output:**
-```json
-{
-  "success": bool,
-  "extractedFiles": [
-    {
-      "fileName": string,
-      "savedPath": string,
-      "size": long
-    }
-  ]
-}
-```
+- Binary stream (application/zip)
+- Content-Disposition: attachment; filename="attachments.zip"
+- ZIP archive containing all extracted files
 
 **Usage:** eParser (ZUGFeRD XML extraction)
 
 ---
 
+### Endpoint: Add Attachment
+**Route:** `POST /api/pdf/attachments/add`  
+**Function:** Embeds one or more files as attachments in a PDF (supports PDF/A-3)
+
+**Input:**
+- PDF file (multipart/form-data)
+- Attachment files (multipart/form-data, multiple)
+
+**Output:**
+- Binary stream (application/pdf)
+- Content-Disposition: attachment; filename="with-attachments.pdf"
+- PDF with embedded attachments
+
+**Usage:** eParser (ZUGFeRD XML embedding), PDF/A-3 archiving
+
+---
+
 ## PdfOperationsController
 
 ### Endpoint: PDF Merge
@@ -125,22 +128,13 @@ This specification defines the controller structure and REST API endpoints for t
 **Function:** Merges multiple PDFs into a single file
 
 **Input:**
-```json
-{
-  "sourceFiles": string[],
-  "outputPath": string
-}
-```
+- Multiple PDF files (multipart/form-data)
+- Field name: "files" (array of IFormFile)
 
 **Output:**
-```json
-{
-  "success": bool,
-  "outputPath": string,
-  "pageCount": int,
-  "fileSize": long
-}
-```
+- Binary stream (application/pdf)
+- Content-Disposition: attachment; filename="merged.pdf"
+- Merged PDF document
 
 **Usage:** signFLOW (Envelope Generator), ErgebnisberichtCreator, ResultHandler (windream)
 
@@ -151,26 +145,22 @@ This specification defines the controller structure and REST API endpoints for t
 **Function:** Adds stamps to PDF pages (APPROVED, CONFIDENTIAL, etc.)
 
 **Input:**
-```json
-{
-  "file": "PDF (multipart/form-data)",
-  "stamp": {
+- PDF file (multipart/form-data)
+- Stamp configuration (JSON):
+  ```json
+  {
     "text": string,
     "position": string,
     "pages": string,
     "color": string,
     "opacity": float
   }
-}
-```
+  ```
 
 **Output:**
-```json
-{
-  "success": bool,
-  "outputPath": string
-}
-```
+- Binary stream (application/pdf)
+- Content-Disposition: attachment; filename="stamped.pdf"
+- PDF with applied stamps
 
 **Usage:** ErgebnisberichtCreator
 
@@ -181,63 +171,75 @@ This specification defines the controller structure and REST API endpoints for t
 **Function:** Adds comments, highlights, and markings to the PDF
 
 **Input:**
-```json
-{
-  "file": "PDF (multipart/form-data)",
-  "annotations": [
-    {
-      "type": string,
-      "page": int,
-      "position": object,
-      "text": string
-    }
-  ]
-}
-```
+- PDF file (multipart/form-data)
+- Annotations (JSON):
+  ```json
+  {
+    "annotations": [
+      {
+        "type": string,
+        "page": int,
+        "position": object,
+        "text": string
+      }
+    ]
+  }
+  ```
 
 **Output:**
-```json
-{
-  "success": bool,
-  "outputPath": string
-}
-```
+- Binary stream (application/pdf)
+- Content-Disposition: attachment; filename="annotated.pdf"
+- PDF with applied annotations
 
 **Usage:** signFLOW (Envelope Generator)
 
 ---
 
-## PdfRenderController
+## SwissQrCodeController
 
-### Endpoint: PDF Preview
-**Route:** `POST /api/pdf/render/preview`  
-**Function:** Renders PDF pages as PNG/JPEG for preview
+### Endpoint: Swiss QR Code Extraction
+**Route:** `POST /api/swissqrcode/extract`  
+**Function:** Extracts and parses Swiss QR Bill (Swiss QR Code) from PDF
 
 **Input:**
-```json
-{
-  "file": "PDF (multipart/form-data)",
-  "page": int,
-  "format": string,
-  "dpi": int
-}
-```
+- PDF file (multipart/form-data)
 
 **Output:**
 ```json
 {
-  "images": [
-    {
-      "page": int,
-      "base64": string,
-      "width": int,
-      "height": int
-    }
-  ]
+  "qrType": "SwissQrBill",
+  "version": "0200",
+  "creditorIban": "CH4431999123000889012",
+  "creditorName": "Example AG",
+  "creditorAddress": {
+    "addressType": "Structured",
+    "street": "Musterstrasse",
+    "houseNumber": "1",
+    "postalCode": "8000",
+    "city": "Zürich",
+    "country": "CH"
+  },
+  "amount": 1234.56,
+  "currency": "CHF",
+  "debtorName": "Max Mustermann",
+  "debtorAddress": { ... },
+  "referenceType": "QRR",
+  "reference": "210000000003139471430009017",
+  "unstructuredMessage": "Invoice #12345",
+  "billInformation": "//S1/10/12345",
+  "alternativeProcedures": ["UV1", "UV2"]
 }
 ```
 
-**Usage:** taskFLOW, fileFLOW, easyFLOW, orgFLOW - PDF preview
+**Usage:** eParser (Swiss QR Bill processing), signFLOW (payment reference extraction)
+
+**Note:** Supports only Structured Address (S-Type) as per Swiss QR Bill Standard 2.0. Combined Address (K-Type) deprecated November 21, 2025.
+
+---
+
+## PdfRenderController
+
+**Status:** REMOVED - PDF preview functionality will be implemented in .NET client library using DevExpress WinForms/WPF controls. Server-side rendering is unnecessary CPU/memory overhead.
 
 ---
 
@@ -248,21 +250,13 @@ This specification defines the controller structure and REST API endpoints for t
 **Function:** Converts a standard PDF to PDF/A
 
 **Input:**
-```json
-{
-  "file": "PDF (multipart/form-data)",
-  "pdfaLevel": string
-}
-```
+- PDF file (multipart/form-data)
+- PDF/A level (query parameter): "PDF/A-1b", "PDF/A-2b", "PDF/A-3b"
 
 **Output:**
-```json
-{
-  "success": bool,
-  "outputPath": string,
-  "pdfaVersion": string
-}
-```
+- Binary stream (application/pdf)
+- Content-Disposition: attachment; filename="converted-pdfa.pdf"
+- PDF/A compliant document
 
 **Usage:** taskFLOW (optional conversion)
 
@@ -273,19 +267,12 @@ This specification defines the controller structure and REST API endpoints for t
 **Function:** Converts PDF/A to a standard PDF
 
 **Input:**
-```json
-{
-  "file": "PDF (multipart/form-data)"
-}
-```
+- PDF/A file (multipart/form-data)
 
 **Output:**
-```json
-{
-  "success": bool,
-  "outputPath": string
-}
-```
+- Binary stream (application/pdf)
+- Content-Disposition: attachment; filename="converted-pdf.pdf"
+- Standard PDF document
 
 **Usage:** taskFLOW (optional conversion)
 
@@ -306,15 +293,27 @@ The service can be used on the client side **without manual HTTP response handli
 
 **Example Client SDK:**
 ```csharp
-var client = new DocumentOperatorClient("https://api.example.com");
+var client = new DocumentServiceClient("https://api.example.com");
 var result = await client.Pdf.Validation.ValidateAsync(pdfFile);
 if (result.IsValid) { ... }
 ```
 
 ### Response Format
-- Default: JSON
+- Default: JSON (for metadata endpoints like validation, check)
+- Binary streams: application/pdf, application/zip (for operations, conversion, extraction)
+- Content-Disposition header: attachment; filename="<output-filename>"
 - Errors: HTTP Status Codes (400, 404, 500) + JSON error object
-- Success: HTTP 200 + JSON response
+- Success: HTTP 200 + JSON/Binary response
+
+**Binary Stream Endpoints:**
+- PDF Operations: merge, stamp, annotate
+- PDF Conversion: to-pdfa, from-pdfa
+- Attachment Operations: extract (ZIP), add (PDF)
+
+**JSON Response Endpoints:**
+- PDF Validation: validate, validate-pdfa
+- Attachment Check: check
+- Swiss QR Code: extract
 
 ### Authentication
 - API Key (Header: `X-API-Key`)
@@ -330,16 +329,21 @@ if (result.IsValid) { ... }
 ## Prioritization
 
 ### Phase 1 (Priority)
-1. PdfValidationController - both endpoints
-2. PdfAttachmentController - both endpoints
-3. PdfOperationsController - Merge endpoint
+1. PdfValidationController - both endpoints (validate, validate-pdfa)
+2. PdfAttachmentController - check endpoint
+3. SwissQrCodeController - extract endpoint (already implemented)
+4. PdfAttachmentController - extract endpoint
+5. PdfOperationsController - merge endpoint
 
 ### Phase 2
-4. PdfOperationsController - Stamp & Annotate
-5. PdfRenderController - Preview
+6. PdfOperationsController - stamp & annotate endpoints
+7. PdfAttachmentController - add attachment endpoint
 
 ### Phase 3
-6. PdfConversionController - both endpoints
+8. PdfConversionController - both endpoints (to-pdfa, from-pdfa)
+
+### Removed
+- PdfRenderController - moved to .NET client library (WinForms/WPF DevExpress controls)
 
 ---
 

DocumentOperator.API/Configuration/DualInputDocumentFilter.cs

@@ -0,0 +1,125 @@
+using Microsoft.AspNetCore.Mvc.ApiExplorer;
+using Microsoft.OpenApi.Models;
+using Swashbuckle.AspNetCore.SwaggerGen;
+
+namespace DocumentService.API.Configuration
+{
+    /// <summary>
+    /// Swagger document filter that merges operations with same path but different [Consumes] attributes.
+    /// Ensures both multipart/form-data and application/json variants are visible in Swagger UI.
+    /// </summary>
+    public class DualInputDocumentFilter : IDocumentFilter
+    {
+        private readonly IApiDescriptionGroupCollectionProvider _apiDescriptionProvider;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DualInputDocumentFilter"/> class.
+        /// </summary>
+        /// <param name="apiDescriptionProvider">API description provider to access all endpoints</param>
+        public DualInputDocumentFilter(IApiDescriptionGroupCollectionProvider apiDescriptionProvider)
+        {
+            _apiDescriptionProvider = apiDescriptionProvider;
+        }
+
+        /// <summary>
+        /// Applies the filter to merge operations with different content types.
+        /// </summary>
+        public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
+        {
+            var allApiDescriptions = _apiDescriptionProvider.ApiDescriptionGroups.Items
+                .SelectMany(g => g.Items)
+                .ToList();
+
+            // Group by path
+            var groupedByPath = allApiDescriptions
+                .GroupBy(x => "/" + x.RelativePath)
+                .ToList();
+
+            foreach (var group in groupedByPath)
+            {
+                var path = group.Key;
+
+                if (!swaggerDoc.Paths.ContainsKey(path))
+                    continue;
+
+                var pathItem = swaggerDoc.Paths[path];
+
+                // Find multipart and JSON variants
+                var multipartDesc = group.FirstOrDefault(x =>
+                    x.SupportedRequestFormats.Any(f => f.MediaType == "multipart/form-data"));
+
+                var jsonDesc = group.FirstOrDefault(x =>
+                    x.SupportedRequestFormats.Any(f => f.MediaType == "application/json"));
+
+                // If we have both variants, merge them into single operation
+                if (multipartDesc != null && jsonDesc != null)
+                {
+                    var httpMethod = multipartDesc.HttpMethod?.ToLowerInvariant();
+                    OperationType operationType;
+
+                    if (!Enum.TryParse<OperationType>(httpMethod, true, out operationType))
+                        continue;
+
+                    if (!pathItem.Operations.ContainsKey(operationType))
+                        continue;
+
+                    var operation = pathItem.Operations[operationType];
+
+                    // Ensure RequestBody exists
+                    if (operation.RequestBody == null)
+                    {
+                        operation.RequestBody = new OpenApiRequestBody
+                        {
+                            Required = true,
+                            Content = new Dictionary<string, OpenApiMediaType>()
+                        };
+                    }
+
+                    // Add multipart/form-data if missing
+                    if (!operation.RequestBody.Content.ContainsKey("multipart/form-data"))
+                    {
+                        operation.RequestBody.Content.Add("multipart/form-data", new OpenApiMediaType
+                        {
+                            Schema = new OpenApiSchema
+                            {
+                                Type = "object",
+                                Properties = new Dictionary<string, OpenApiSchema>
+                                {
+                                    ["file"] = new OpenApiSchema
+                                    {
+                                        Type = "string",
+                                        Format = "binary",
+                                        Description = "PDF file to upload"
+                                    }
+                                },
+                                Required = new HashSet<string> { "file" }
+                            }
+                        });
+                    }
+
+                    // Add application/json if missing
+                    if (!operation.RequestBody.Content.ContainsKey("application/json"))
+                    {
+                        operation.RequestBody.Content.Add("application/json", new OpenApiMediaType
+                        {
+                            Schema = new OpenApiSchema
+                            {
+                                Type = "object",
+                                Properties = new Dictionary<string, OpenApiSchema>
+                                {
+                                    ["base64Pdf"] = new OpenApiSchema
+                                    {
+                                        Type = "string",
+                                        Format = "byte",
+                                        Description = "Base64-encoded PDF file content"
+                                    }
+                                },
+                                Required = new HashSet<string> { "base64Pdf" }
+                            }
+                        });
+                    }
+                }
+            }
+        }
+    }
+}

DocumentOperator.API/Configuration/SerilogConfiguration.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.API.Configuration
+namespace DocumentService.API.Configuration
 {
     /// <summary>
     /// Placeholder class for Serilog configuration extensions.

DocumentOperator.API/Configuration/SwaggerConfiguration.cs

@@ -1,7 +1,8 @@
-using Microsoft.OpenApi.Models;
+using Microsoft.Extensions.Options;
+using Microsoft.OpenApi.Models;
 using System.Reflection;
 
-namespace DocumentOperator.API.Configuration
+namespace DocumentService.API.Configuration
 {
     /// <summary>
     /// Provides extension methods for configuring Swagger/OpenAPI documentation.
@@ -12,18 +13,31 @@ namespace DocumentOperator.API.Configuration
         /// Adds Swagger documentation generation to the service collection.
         /// </summary>
         /// <param name="services">The service collection to add Swagger to.</param>
+        /// <param name="configuration">Configuration to read SwaggerSettings from.</param>
         /// <returns>The modified service collection.</returns>
-        public static IServiceCollection AddSwaggerDocumentation(this IServiceCollection services)
+        public static IServiceCollection AddSwaggerDocumentation(
+            this IServiceCollection services,
+            IConfiguration configuration)
         {
+            var swaggerSettings = configuration.GetSection(SwaggerSettings.SectionName).Get<SwaggerSettings>()
+                ?? new SwaggerSettings();
+
             services.AddSwaggerGen(options =>
             {
-                options.SwaggerDoc("v1", new OpenApiInfo
+                options.SwaggerDoc(swaggerSettings.Version, new OpenApiInfo
                 {
-                    Title = "DD Document Operator API",
-                    Version = "v1",
-                    Description = "PDF Verarbeitungs-Service für Validierung, Stempel, Zertifikate, Anhänge & Zusammenführung"
+                    Title = swaggerSettings.Title,
+                    Version = swaggerSettings.Version,
+                    Description = swaggerSettings.Description
                 });
 
+                // Resolve conflicting actions: Keep first variant
+                // DualInputDocumentFilter will merge both variants into single operation
+                options.ResolveConflictingActions(apiDescriptions => apiDescriptions.First());
+
+                // Add document filter to merge operations with different content types
+                options.DocumentFilter<DualInputDocumentFilter>();
+
                 // XML-Kommentare einbinden
                 var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
                 var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);

DocumentOperator.API/Configuration/SwaggerSettings.cs

@@ -0,0 +1,33 @@
+namespace DocumentService.API.Configuration;
+
+/// <summary>
+/// Configuration settings for Swagger/OpenAPI documentation.
+/// </summary>
+public class SwaggerSettings
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public const string SectionName = "SwaggerSettings";
+
+    /// <summary>
+    /// Enable Swagger UI in Production environment.
+    /// Default: true (allows production testing/debugging).
+    /// </summary>
+    public bool EnableInProduction { get; set; } = true;
+
+    /// <summary>
+    /// API title displayed in Swagger UI.
+    /// </summary>
+    public string Title { get; set; } = "DocumentService API";
+
+    /// <summary>
+    /// API version.
+    /// </summary>
+    public string Version { get; set; } = "v1";
+
+    /// <summary>
+    /// API description displayed in Swagger UI.
+    /// </summary>
+    public string Description { get; set; } = "PDF document processing service";
+}

DocumentOperator.API/Controllers/PdfAttachmentController.cs

@@ -0,0 +1,356 @@
+using DocumentService.Application.AddAttachments;
+using DocumentService.Application.CheckPdfAttachments.Queries;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.ExtractPdfAttachments;
+using DocumentService.Client.Models.Requests;
+using DocumentService.Domain.Common.Exceptions;
+using MediatR;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DocumentService.API.Controllers;
+
+/// <summary>
+/// Controller for PDF attachment operations (detection, extraction, embedding)
+/// </summary>
+[ApiController]
+[Route("api/pdf/attachments")]
+[Produces("application/json")]
+public class PdfAttachmentController(IMediator mediator) : ControllerBase
+{
+    /// <summary>
+    /// Checks if a PDF contains embedded files (attachments) and returns their metadata.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="file">The PDF file to check for attachments</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Attachment check result with metadata for all found attachments</returns>
+    /// <response code="200">PDF successfully checked - returns attachment details</response>
+    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("check")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(AttachmentCheckResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> CheckAttachmentsFromFile(
+        IFormFile file,
+        CancellationToken cancellationToken)
+    {
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+
+        // Send query to MediatR (ValidationBehavior runs automatically)
+        var query = new CheckPdfAttachmentsQuery { PdfStream = pdfStream };
+        var result = await mediator.Send(query, cancellationToken);
+
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Checks if a PDF contains embedded files (attachments) and returns their metadata.
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Attachment check result with metadata for all found attachments</returns>
+    /// <response code="200">PDF successfully checked - returns attachment details</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("check")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(AttachmentCheckResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> CheckAttachmentsFromBase64(
+        [FromBody] CheckPdfAttachmentsRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+        
+        // Send query to MediatR (ValidationBehavior runs automatically)
+        var query = new CheckPdfAttachmentsQuery { PdfStream = pdfStream };
+        var result = await mediator.Send(query, cancellationToken);
+
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Extracts all embedded files from a PDF and returns them as a ZIP archive.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="file">The PDF file to extract attachments from</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>ZIP archive containing all extracted attachments</returns>
+    /// <response code="200">Attachments extracted successfully - returns ZIP file</response>
+    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
+    /// <response code="404">PDF contains no attachments</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("extract")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ExtractAttachmentsFromFile(
+        IFormFile file,
+        CancellationToken cancellationToken)
+    {
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+
+        // Send command to MediatR
+        var command = new ExtractPdfAttachmentsCommand { PdfStream = pdfStream };
+        byte[] zipBytes = await mediator.Send(command, cancellationToken);
+
+        // Return ZIP file
+        return File(zipBytes, "application/zip", "attachments.zip");
+    }
+
+    /// <summary>
+    /// Extracts all embedded files from a PDF and returns them as a ZIP archive.
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>ZIP archive containing all extracted attachments</returns>
+    /// <response code="200">Attachments extracted successfully - returns ZIP file</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
+    /// <response code="404">PDF contains no attachments</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("extract")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ExtractAttachmentsFromBase64(
+        [FromBody] ExtractPdfAttachmentsRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+
+        // Send command to MediatR
+        var command = new ExtractPdfAttachmentsCommand { PdfStream = pdfStream };
+        byte[] zipBytes = await mediator.Send(command, cancellationToken);
+
+        // Return ZIP file
+        return File(zipBytes, "application/zip", "attachments.zip");
+    }
+
+    /// <summary>
+    /// Embeds one or more files as attachments in a PDF document (supports PDF/A-3).
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="pdfFile">The PDF file to add attachments to</param>
+    /// <param name="attachmentFiles">Files to embed as attachments (one or more)</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>PDF with embedded attachments</returns>
+    /// <response code="200">Attachments added successfully - returns PDF</response>
+    /// <response code="400">Invalid input (file missing, not a PDF, or no attachments provided)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [Obsolete("This endpoint is not implemented yet.")]
+    [HttpPost("add")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> AddAttachmentsFromFile(
+        IFormFile pdfFile,
+        List<IFormFile> attachmentFiles,
+        CancellationToken cancellationToken)
+    {
+        if (pdfFile == null || pdfFile.Length == 0)
+        {
+            throw new BadRequestException("PDF file is required");
+        }
+
+        if (attachmentFiles == null || attachmentFiles.Count == 0)
+        {
+            throw new BadRequestException("At least one attachment file is required");
+        }
+
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = pdfFile.OpenReadStream();
+
+        // Convert attachment files to AttachmentFile records
+        var attachments = new List<AttachmentFile>();
+        foreach (var file in attachmentFiles)
+        {
+            using var ms = new MemoryStream();
+            await file.CopyToAsync(ms, cancellationToken);
+            
+            attachments.Add(new AttachmentFile
+            {
+                FileName = file.FileName,
+                Content = ms.ToArray(),
+                MimeType = file.ContentType
+            });
+        }
+
+        // Send command to MediatR
+        var command = new AddAttachmentsCommand 
+        { 
+            PdfStream = pdfStream,
+            Attachments = attachments
+        };
+        byte[] resultPdf = await mediator.Send(command, cancellationToken);
+
+        // Return PDF with attachments
+        return File(resultPdf, "application/pdf", "with-attachments.pdf");
+    }
+
+    /// <summary>
+    /// Embeds one or more files as attachments in a PDF document (supports PDF/A-3).
+    /// Supports Base64-encoded PDF and attachments via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF and attachments</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>PDF with embedded attachments</returns>
+    /// <response code="200">Attachments added successfully - returns PDF</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF, or no attachments provided)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [Obsolete("This endpoint is not implemented yet.")]
+    [HttpPost("add")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> AddAttachmentsFromBase64(
+        [FromBody] AddAttachmentsRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 PDF to stream
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 PDF format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+
+        // Convert Base64 attachments to AttachmentFile records
+        var attachments = new List<AttachmentFile>();
+        foreach (var att in request.Attachments)
+        {
+            byte[] attBytes;
+            try
+            {
+                attBytes = Convert.FromBase64String(att.Base64Content);
+            }
+            catch (FormatException ex)
+            {
+                throw new BadRequestException($"Invalid Base64 format for attachment '{att.FileName}': " + ex.Message);
+            }
+
+            attachments.Add(new AttachmentFile
+            {
+                FileName = att.FileName,
+                Content = attBytes,
+                MimeType = att.MimeType
+            });
+        }
+
+        // Send command to MediatR
+        var command = new AddAttachmentsCommand 
+        { 
+            PdfStream = pdfStream,
+            Attachments = attachments
+        };
+        byte[] resultPdf = await mediator.Send(command, cancellationToken);
+
+        // Return PDF with attachments
+        return File(resultPdf, "application/pdf", "with-attachments.pdf");
+    }
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF attachment check
+/// </summary>
+public record CheckPdfAttachmentsRequest
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public string Base64Pdf { get; init; } = string.Empty;
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF attachment extraction
+/// </summary>
+public record ExtractPdfAttachmentsRequest
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public required string Base64Pdf { get; init; }
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF with attachments to add
+/// </summary>
+public record AddAttachmentsRequest
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public required string Base64Pdf { get; init; }
+
+    /// <summary>
+    /// List of attachments to embed
+    /// </summary>
+    public required List<AttachmentRequestDto> Attachments { get; init; }
+}
+
+/// <summary>
+/// DTO for attachment file in request
+/// </summary>
+public record AttachmentRequestDto
+{
+    /// <summary>
+    /// File name (e.g., "invoice.xml", "document.pdf")
+    /// </summary>
+    /// <example>factur-x.xml</example>
+    public required string FileName { get; init; }
+
+    /// <summary>
+    /// File content encoded as Base64 string
+    /// </summary>
+    /// <example>PD94bWwgdmVyc2lvbj0iMS4wIj8+...</example>
+    public required string Base64Content { get; init; }
+
+    /// <summary>
+    /// MIME type (optional, e.g., "application/xml")
+    /// </summary>
+    /// <example>application/xml</example>
+    public string? MimeType { get; init; }
+}

DocumentOperator.API/Controllers/PdfConversionController.cs

@@ -0,0 +1,182 @@
+using DocumentService.Application.ConvertFromPdfA;
+using DocumentService.Application.ConvertToPdfA;
+using DocumentService.Client.Models.Requests;
+using DocumentService.Domain.Common.Exceptions;
+using MediatR;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DocumentService.API.Controllers;
+
+/// <summary>
+/// Controller for PDF conversion operations (PDF ? PDF/A)
+/// </summary>
+[ApiController]
+[Route("api/pdf/conversion")]
+[Obsolete("This endpoint is not implemented yet.")]
+public class PdfConversionController(IMediator mediator) : ControllerBase
+{
+    /// <summary>
+    /// Converts a standard PDF to PDF/A format.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="file">The PDF file to convert</param>
+    /// <param name="pdfALevel">Target PDF/A level (e.g., "PDF/A-1b", "PDF/A-2b", "PDF/A-3b")</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>PDF/A compliant document</returns>
+    /// <response code="200">PDF converted to PDF/A successfully</response>
+    /// <response code="400">Invalid input (file missing, not a PDF, or invalid PDF/A level)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [Obsolete("This endpoint is not implemented yet.")]
+    [HttpPost("to-pdfa")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ConvertToPdfAFromFile(
+        IFormFile file,
+        [FromQuery] string pdfALevel = "PDF/A-3b",
+        CancellationToken cancellationToken = default)
+    {
+        if (file == null || file.Length == 0)
+        {
+            throw new BadRequestException("PDF file is required");
+        }
+
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+
+        // Send command to MediatR
+        var command = new ConvertToPdfACommand 
+        { 
+            PdfStream = pdfStream,
+            PdfALevel = pdfALevel
+        };
+        byte[] resultPdf = await mediator.Send(command, cancellationToken);
+
+        // Return PDF/A file
+        return File(resultPdf, "application/pdf", "converted-pdfa.pdf");
+    }
+
+    /// <summary>
+    /// Converts a standard PDF to PDF/A format.
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF and PDF/A level</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>PDF/A compliant document</returns>
+    /// <response code="200">PDF converted to PDF/A successfully</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF, or invalid PDF/A level)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [Obsolete("This endpoint is not implemented yet.")]
+    [HttpPost("to-pdfa")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ConvertToPdfAFromBase64(
+        [FromBody] ConvertToPdfARequest request,
+        CancellationToken cancellationToken = default)
+    {
+        // Convert Base64 PDF to stream
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 PDF format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+
+        // Send command to MediatR
+        var command = new ConvertToPdfACommand 
+        { 
+            PdfStream = pdfStream,
+            PdfALevel = request.PdfALevel ?? "PDF/A-3b"
+        };
+        byte[] resultPdf = await mediator.Send(command, cancellationToken);
+
+        // Return PDF/A file
+        return File(resultPdf, "application/pdf", "converted-pdfa.pdf");
+    }
+
+    /// <summary>
+    /// Converts a PDF/A document to a standard PDF (removes PDF/A restrictions).
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="file">The PDF/A file to convert</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Standard PDF document</returns>
+    /// <response code="200">PDF/A converted to standard PDF successfully</response>
+    /// <response code="400">Invalid input (file missing, not a PDF)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [Obsolete("This endpoint is not implemented yet.")]
+    [HttpPost("from-pdfa")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ConvertFromPdfAFromFile(
+        IFormFile file,
+        CancellationToken cancellationToken = default)
+    {
+        if (file == null || file.Length == 0)
+        {
+            throw new BadRequestException("PDF/A file is required");
+        }
+
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+
+        // Send command to MediatR
+        var command = new ConvertFromPdfACommand { PdfStream = pdfStream };
+        byte[] resultPdf = await mediator.Send(command, cancellationToken);
+
+        // Return standard PDF file
+        return File(resultPdf, "application/pdf", "converted-pdf.pdf");
+    }
+
+    /// <summary>
+    /// Converts a PDF/A document to a standard PDF (removes PDF/A restrictions).
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF/A</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Standard PDF document</returns>
+    /// <response code="200">PDF/A converted to standard PDF successfully</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [Obsolete("This endpoint is not implemented yet.")]
+    [HttpPost("from-pdfa")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ConvertFromPdfAFromBase64(
+        [FromBody] ConvertFromPdfARequest request,
+        CancellationToken cancellationToken = default)
+    {
+        // Convert Base64 PDF to stream
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 PDF format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+
+        // Send command to MediatR
+        var command = new ConvertFromPdfACommand { PdfStream = pdfStream };
+        byte[] resultPdf = await mediator.Send(command, cancellationToken);
+
+        // Return standard PDF file
+        return File(resultPdf, "application/pdf", "converted-pdf.pdf");
+    }
+}

DocumentOperator.API/Controllers/PdfOperationsController.cs

@@ -0,0 +1,728 @@
+using DocumentService.Application.AddAnnotation;
+using DocumentService.Application.AddStamp;
+using DocumentService.Application.MergePdfs;
+using DocumentService.Domain.Common.Exceptions;
+using DocumentService.Domain.Models.ValueObjects;
+using MediatR;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DocumentService.API.Controllers;
+
+/// <summary>
+/// Controller for PDF operations (merge, stamp, annotate).
+/// </summary>
+[ApiController]
+[Route("api/pdf/operations")]
+public class PdfOperationsController(IMediator mediator) : ControllerBase
+{
+    /// <summary>
+    /// Merges multiple PDF files into a single PDF.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="files">PDF files to merge (minimum 2 required)</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Merged PDF file</returns>
+    /// <response code="200">PDFs merged successfully - returns merged PDF</response>
+    /// <response code="400">Invalid input (fewer than 2 files, corrupted PDF)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("merge", Name = "MergeFromFiles")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> MergeFromFiles(
+        [FromForm] List<IFormFile> files,
+        CancellationToken cancellationToken)
+    {
+        // Convert IFormFile[] to Stream[] (use OpenReadStream directly - no buffering)
+        var streams = files.Select(f => f.OpenReadStream()).ToList();
+
+        // Send command to MediatR (no page ranges for now - multipart binding is complex)
+        var command = new MergePdfsCommand 
+        { 
+            PdfStreams = streams,
+            PageRanges = null
+        };
+        
+        byte[] mergedPdf = await mediator.Send(command, cancellationToken);
+
+        // Return merged PDF
+        return File(mergedPdf, "application/pdf", "merged.pdf");
+    }
+
+    /// <summary>
+    /// Merges multiple PDF files into a single PDF.
+    /// Supports Base64-encoded PDFs via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDFs and optional page ranges</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Merged PDF file</returns>
+    /// <response code="200">PDFs merged successfully - returns merged PDF</response>
+    /// <response code="400">Invalid input (Base64 format error, fewer than 2 files, corrupted PDF, invalid page range)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("merge", Name = "MergeFromBase64")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> MergeFromBase64(
+        [FromBody] MergePdfsBase64Request request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64[] to MemoryStream[]
+        List<Stream> streams = [];
+        try
+        {
+            foreach (var base64Pdf in request.Base64Pdfs)
+            {
+                byte[] pdfBytes = Convert.FromBase64String(base64Pdf);
+                streams.Add(new MemoryStream(pdfBytes));
+            }
+        }
+        catch (FormatException ex)
+        {
+            // Dispose opened streams on error
+            foreach (var stream in streams) stream.Dispose();
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+
+        var command = new MergePdfsCommand 
+        { 
+            PdfStreams = streams,
+            PageRanges = request.PageRanges
+        };
+        
+        byte[] mergedPdf = await mediator.Send(command, cancellationToken);
+
+        // Cleanup streams (important for MemoryStreams we created)
+        foreach (var stream in streams) stream.Dispose();
+
+        return File(mergedPdf, "application/pdf", "merged.pdf");
+    }
+
+    /// <summary>
+    /// Adds an annotation to a PDF document.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="request">Multipart form data containing PDF file and annotation parameters</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Annotated PDF file</returns>
+    /// <response code="200">Annotation added successfully - returns annotated PDF</response>
+    /// <response code="400">Invalid input (invalid page number, missing required parameters)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("annotate", Name = "AnnotateFromFile")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> AnnotateFromFile(
+        [FromForm] AddAnnotationMultipartRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Calculate X2, Y2 from Width/Height if provided
+        double x2 = request.X2 ?? request.X1 + (request.Width ?? throw new BadRequestException("Either X2 or Width must be provided"));
+        double y2 = request.Y2 ?? request.Y1 + (request.Height ?? throw new BadRequestException("Either Y2 or Height must be provided"));
+
+        var command = new AddAnnotationCommand
+        {
+            PdfStream = request.File.OpenReadStream(),
+            AnnotationType = request.AnnotationType,
+            PageNumber = request.PageNumber,
+            Rectangle = (request.X1, request.Y1, x2, y2),
+            Content = request.Content,
+            Author = request.Author,
+            Color = request.Color,
+            TextMarkupStyle = request.TextMarkupStyle,
+            Origin = request.Origin
+        };
+
+        byte[] annotatedPdf = await mediator.Send(command, cancellationToken);
+
+        return File(annotatedPdf, "application/pdf", "annotated.pdf");
+    }
+
+    /// <summary>
+    /// Adds an annotation to a PDF document.
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="command">Command containing all annotation parameters (including Base64 PDF)</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Annotated PDF file</returns>
+    /// <response code="200">Annotation added successfully - returns annotated PDF</response>
+    /// <response code="400">Invalid input (Base64 format error, invalid page number, missing required parameters)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("annotate", Name = "AnnotateFromBase64")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> AnnotateFromBase64(
+        [FromBody] AddAnnotationBase64Command command,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 to MemoryStream
+        Stream pdfStream;
+        try
+        {
+            byte[] pdfBytes = Convert.FromBase64String(command.Base64Pdf);
+            pdfStream = new MemoryStream(pdfBytes);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+
+        // Calculate X2, Y2 from Width/Height if provided
+        double x2 = command.X2 ?? command.X1 + (command.Width ?? throw new BadRequestException("Either X2 or Width must be provided"));
+        double y2 = command.Y2 ?? command.Y1 + (command.Height ?? throw new BadRequestException("Either Y2 or Height must be provided"));
+
+        var annotationCommand = new AddAnnotationCommand
+        {
+            PdfStream = pdfStream,
+            AnnotationType = command.AnnotationType,
+            PageNumber = command.PageNumber,
+            Rectangle = (command.X1, command.Y1, x2, y2),
+            Content = command.Content,
+            Author = command.Author,
+            Color = command.Color,
+            TextMarkupStyle = command.TextMarkupStyle,
+            Origin = command.Origin
+        };
+
+        byte[] annotatedPdf = await mediator.Send(annotationCommand, cancellationToken);
+
+        // Cleanup stream
+        pdfStream.Dispose();
+
+        return File(annotatedPdf, "application/pdf", "annotated.pdf");
+    }
+
+    /// <summary>
+    /// Adds a stamp (text, image, or predefined) to PDF pages.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="request">Multipart form data containing PDF file and stamp parameters</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Stamped PDF file</returns>
+    /// <response code="200">Stamp added successfully - returns stamped PDF</response>
+    /// <response code="400">Invalid input (invalid page number, missing required parameters, invalid image format)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("stamp", Name = "AddStampFromFile")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> AddStampFromFile(
+        [FromForm] AddStampMultipartRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Convert ImageFile to byte[] if provided
+        byte[]? imageBytes = null;
+        if (request.ImageFile != null)
+        {
+            using var ms = new MemoryStream();
+            await request.ImageFile.CopyToAsync(ms, cancellationToken);
+            imageBytes = ms.ToArray();
+        }
+
+        var command = new AddStampCommand
+        {
+            PdfStream = request.File.OpenReadStream(),
+            StampType = request.StampType,
+            PageNumbers = request.PageNumbers,
+            Position = (request.X, request.Y),
+            Size = request.Width.HasValue && request.Height.HasValue 
+                ? (request.Width.Value, request.Height.Value) 
+                : null,
+            Origin = request.Origin,
+            Text = request.Text,
+            FontName = request.FontName,
+            FontSize = request.FontSize,
+            Color = request.Color,
+            Opacity = request.Opacity,
+            Rotation = request.Rotation,
+            Placement = request.Placement,
+            ImageBytes = imageBytes,
+            PredefinedType = request.PredefinedType
+        };
+
+        byte[] stampedPdf = await mediator.Send(command, cancellationToken);
+
+        return File(stampedPdf, "application/pdf", "stamped.pdf");
+    }
+
+    /// <summary>
+    /// Adds a stamp (text, image, or predefined) to PDF pages.
+    /// Supports Base64-encoded PDF and image via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF, stamp parameters, and optional Base64 image</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>Stamped PDF file</returns>
+    /// <response code="200">Stamp added successfully - returns stamped PDF</response>
+    /// <response code="400">Invalid input (Base64 format error, invalid page number, missing required parameters)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("stamp", Name = "AddStampFromBase64")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> AddStampFromBase64(
+        [FromBody] AddStampBase64Request request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 PDF to MemoryStream
+        Stream pdfStream;
+        try
+        {
+            byte[] pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+            pdfStream = new MemoryStream(pdfBytes);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 PDF format: " + ex.Message);
+        }
+
+        // Convert Base64 image to byte[] if provided
+        byte[]? imageBytes = null;
+        if (!string.IsNullOrWhiteSpace(request.Base64Image))
+        {
+            try
+            {
+                imageBytes = Convert.FromBase64String(request.Base64Image);
+            }
+            catch (FormatException ex)
+            {
+                pdfStream.Dispose();
+                throw new BadRequestException("Invalid Base64 image format: " + ex.Message);
+            }
+        }
+
+        var command = new AddStampCommand
+        {
+            PdfStream = pdfStream,
+            StampType = request.StampType,
+            PageNumbers = request.PageNumbers,
+            Position = (request.X, request.Y),
+            Size = request.Width.HasValue && request.Height.HasValue 
+                ? (request.Width.Value, request.Height.Value) 
+                : null,
+            Origin = request.Origin,
+            Text = request.Text,
+            FontName = request.FontName,
+            FontSize = request.FontSize,
+            Color = request.Color,
+            Opacity = request.Opacity,
+            Rotation = request.Rotation,
+            Placement = request.Placement,
+            ImageBytes = imageBytes,
+            PredefinedType = request.PredefinedType
+        };
+
+        byte[] stampedPdf = await mediator.Send(command, cancellationToken);
+
+        // Cleanup stream
+        pdfStream.Dispose();
+
+        return File(stampedPdf, "application/pdf", "stamped.pdf");
+    }
+}
+
+/// <summary>
+/// Request DTO for multipart/form-data annotation operation
+/// </summary>
+public class AddAnnotationMultipartRequest
+{
+    /// <summary>
+    /// PDF file to annotate
+    /// </summary>
+    public required IFormFile File { get; set; }
+
+    /// <summary>
+    /// Type of annotation (TextMarkup, FreeText, StickyNote, Circle, Square)
+    /// </summary>
+    public required AnnotationType AnnotationType { get; set; }
+
+    /// <summary>
+    /// Target page number (1-indexed)
+    /// </summary>
+    public required int PageNumber { get; set; }
+
+    /// <summary>
+    /// Rectangle X1 coordinate (left)
+    /// </summary>
+    public required double X1 { get; set; }
+
+    /// <summary>
+    /// Rectangle Y1 coordinate (top or bottom depending on Origin)
+    /// </summary>
+    public required double Y1 { get; set; }
+
+    /// <summary>
+    /// Rectangle X2 coordinate (right). Optional if Width is provided.
+    /// </summary>
+    public double? X2 { get; set; }
+
+    /// <summary>
+    /// Rectangle Y2 coordinate (bottom or top depending on Origin). Optional if Height is provided.
+    /// </summary>
+    public double? Y2 { get; set; }
+
+    /// <summary>
+    /// Rectangle width. Alternative to X2 (X2 = X1 + Width). Optional if X2 is provided.
+    /// </summary>
+    public double? Width { get; set; }
+
+    /// <summary>
+    /// Rectangle height. Alternative to Y2 (Y2 = Y1 + Height). Optional if Y2 is provided.
+    /// </summary>
+    public double? Height { get; set; }
+
+    /// <summary>
+    /// Annotation content (required for FreeText/StickyNote)
+    /// </summary>
+    public string? Content { get; set; }
+
+    /// <summary>
+    /// Author name (optional)
+    /// </summary>
+    public string? Author { get; set; }
+
+    /// <summary>
+    /// Hex color (6 digits, e.g., "FF0000" for red)
+    /// </summary>
+    public string? Color { get; set; }
+
+    /// <summary>
+    /// Markup style (Highlight/Underline/Strikeout, required for TextMarkup)
+    /// </summary>
+    public TextMarkupStyle? TextMarkupStyle { get; set; }
+
+    /// <summary>
+    /// Coordinate origin (BottomLeft = PDF native, TopLeft = UI-friendly). Default: BottomLeft
+    /// </summary>
+    public AnnotationOrigin Origin { get; set; } = AnnotationOrigin.BottomLeft;
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF merge operation (API layer only - converts to MergePdfsCommand)
+/// </summary>
+public record MergePdfsBase64Request
+{
+    /// <summary>
+    /// Array of Base64-encoded PDF files (minimum 2 required)
+    /// </summary>
+    /// <example>["JVBERi0xLjQK...", "JVBERi0xLjQK..."]</example>
+    public required List<string> Base64Pdfs { get; init; }
+
+    /// <summary>
+    /// Optional page ranges per PDF (null = all pages). 
+    /// Format: "1-3,5" means pages 1, 2, 3, and 5.
+    /// If provided, array length must match Base64Pdfs length.
+    /// </summary>
+    /// <example>["1-2", "1,3,5", null]</example>
+    public List<string?>? PageRanges { get; init; }
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF annotation (API layer only - converts to AddAnnotationCommand)
+/// </summary>
+public record AddAnnotationBase64Command
+{
+    /// <summary>
+    /// Base64-encoded PDF file
+    /// </summary>
+    /// <example>"JVBERi0xLjQK..."</example>
+    public required string Base64Pdf { get; init; }
+
+    /// <summary>
+    /// Type of annotation to add
+    /// </summary>
+    /// <example>TextMarkup</example>
+    public required AnnotationType AnnotationType { get; init; }
+
+    /// <summary>
+    /// Target page number (1-indexed)
+    /// </summary>
+    /// <example>1</example>
+    public required int PageNumber { get; init; }
+
+    /// <summary>
+    /// Rectangle X1 coordinate (left)
+    /// </summary>
+    /// <example>100.0</example>
+    public required double X1 { get; init; }
+
+    /// <summary>
+    /// Rectangle Y1 coordinate (top or bottom depending on Origin)
+    /// </summary>
+    /// <example>100.0</example>
+    public required double Y1 { get; init; }
+
+    /// <summary>
+    /// Rectangle X2 coordinate (right). Optional if Width is provided.
+    /// </summary>
+    /// <example>200.0</example>
+    public double? X2 { get; init; }
+
+    /// <summary>
+    /// Rectangle Y2 coordinate (bottom or top depending on Origin). Optional if Height is provided.
+    /// </summary>
+    /// <example>120.0</example>
+    public double? Y2 { get; init; }
+
+    /// <summary>
+    /// Rectangle width. Alternative to X2 (X2 = X1 + Width). Optional if X2 is provided.
+    /// </summary>
+    /// <example>100.0</example>
+    public double? Width { get; init; }
+
+    /// <summary>
+    /// Rectangle height. Alternative to Y2 (Y2 = Y1 + Height). Optional if Y2 is provided.
+    /// </summary>
+    /// <example>20.0</example>
+    public double? Height { get; init; }
+
+    /// <summary>
+    /// Annotation content (required for FreeText and StickyNote)
+    /// </summary>
+    /// <example>"Important text to highlight"</example>
+    public string? Content { get; init; }
+
+    /// <summary>
+    /// Author name (optional)
+    /// </summary>
+    /// <example>"John Doe"</example>
+    public string? Author { get; init; }
+
+    /// <summary>
+    /// Hex color (6 digits, e.g., "FF0000" for red). Optional - defaults vary by annotation type.
+    /// </summary>
+    /// <example>"FFFF00"</example>
+    public string? Color { get; init; }
+
+    /// <summary>
+    /// Text markup style (Highlight, Underline, or Strikeout). Required for TextMarkup annotations.
+    /// </summary>
+    /// <example>Highlight</example>
+    public TextMarkupStyle? TextMarkupStyle { get; init; }
+
+    /// <summary>
+    /// Coordinate origin (BottomLeft = PDF native, TopLeft = UI-friendly). Default: BottomLeft
+    /// </summary>
+    /// <example>BottomLeft</example>
+    public AnnotationOrigin Origin { get; init; } = AnnotationOrigin.BottomLeft;
+}
+
+/// <summary>
+/// Request DTO for multipart/form-data stamp operation
+/// </summary>
+public class AddStampMultipartRequest
+{
+    /// <summary>
+    /// PDF file to stamp
+    /// </summary>
+    public required IFormFile File { get; set; }
+
+    /// <summary>
+    /// Type of stamp (Text, Image, or Predefined)
+    /// </summary>
+    public required StampType StampType { get; set; }
+
+    /// <summary>
+    /// Target page numbers (1-indexed). Null or empty = all pages.
+    /// </summary>
+    /// <example>[1, 3, 5]</example>
+    public int[]? PageNumbers { get; set; }
+
+    /// <summary>
+    /// Stamp position X coordinate
+    /// </summary>
+    /// <example>100.0</example>
+    public required double X { get; set; }
+
+    /// <summary>
+    /// Stamp position Y coordinate
+    /// </summary>
+    /// <example>100.0</example>
+    public required double Y { get; set; }
+
+    /// <summary>
+    /// Stamp width (optional, auto-size for images if not specified)
+    /// </summary>
+    /// <example>200.0</example>
+    public double? Width { get; set; }
+
+    /// <summary>
+    /// Stamp height (optional, auto-size for images if not specified)
+    /// </summary>
+    /// <example>50.0</example>
+    public double? Height { get; set; }
+
+    /// <summary>
+    /// Coordinate origin (BottomLeft = PDF native, TopLeft = UI-friendly). Default: BottomLeft
+    /// </summary>
+    /// <example>BottomLeft</example>
+    public AnnotationOrigin Origin { get; set; } = AnnotationOrigin.BottomLeft;
+
+    /// <summary>
+    /// Text content (required for Text stamps)
+    /// </summary>
+    /// <example>"CONFIDENTIAL"</example>
+    public string? Text { get; set; }
+
+    /// <summary>
+    /// Font name (default: Arial)
+    /// </summary>
+    /// <example>"Arial"</example>
+    public string? FontName { get; set; }
+
+    /// <summary>
+    /// Font size in points (default: 12)
+    /// </summary>
+    /// <example>24.0</example>
+    public double? FontSize { get; set; }
+
+    /// <summary>
+    /// Hex color (6 digits, e.g., "FF0000" for red, default: "000000")
+    /// </summary>
+    /// <example>"FF0000"</example>
+    public string? Color { get; set; }
+
+    /// <summary>
+    /// Opacity (0.0 = transparent, 1.0 = opaque, default: 0.5)
+    /// </summary>
+    /// <example>0.5</example>
+    public double? Opacity { get; set; }
+
+    /// <summary>
+    /// Rotation angle in degrees (0-360, default: 0)
+    /// </summary>
+    /// <example>45.0</example>
+    public double? Rotation { get; set; }
+
+    /// <summary>
+    /// Stamp placement (Foreground = on top, Background = watermark effect, default: Foreground)
+    /// </summary>
+    /// <example>Foreground</example>
+    public StampPlacement Placement { get; set; } = StampPlacement.Foreground;
+
+    /// <summary>
+    /// Image file (required for Image stamps, PNG/JPEG)
+    /// </summary>
+    public IFormFile? ImageFile { get; set; }
+
+    /// <summary>
+    /// Predefined stamp type (required for Predefined stamps)
+    /// </summary>
+    /// <example>Confidential</example>
+    public PredefinedStampType? PredefinedType { get; set; }
+}
+
+/// <summary>
+/// Request DTO for Base64-encoded PDF stamp operation (API layer only - converts to AddStampCommand)
+/// </summary>
+public record AddStampBase64Request
+{
+    /// <summary>
+    /// Base64-encoded PDF file
+    /// </summary>
+    /// <example>"JVBERi0xLjQK..."</example>
+    public required string Base64Pdf { get; init; }
+
+    /// <summary>
+    /// Type of stamp (Text, Image, or Predefined)
+    /// </summary>
+    /// <example>Text</example>
+    public required StampType StampType { get; init; }
+
+    /// <summary>
+    /// Target page numbers (1-indexed). Null or empty = all pages.
+    /// </summary>
+    /// <example>[1, 3, 5]</example>
+    public int[]? PageNumbers { get; init; }
+
+    /// <summary>
+    /// Stamp position X coordinate
+    /// </summary>
+    /// <example>100.0</example>
+    public required double X { get; init; }
+
+    /// <summary>
+    /// Stamp position Y coordinate
+    /// </summary>
+    /// <example>100.0</example>
+    public required double Y { get; init; }
+
+    /// <summary>
+    /// Stamp width (optional, auto-size for images if not specified)
+    /// </summary>
+    /// <example>200.0</example>
+    public double? Width { get; init; }
+
+    /// <summary>
+    /// Stamp height (optional, auto-size for images if not specified)
+    /// </summary>
+    /// <example>50.0</example>
+    public double? Height { get; init; }
+
+    /// <summary>
+    /// Coordinate origin (BottomLeft = PDF native, TopLeft = UI-friendly). Default: BottomLeft
+    /// </summary>
+    /// <example>BottomLeft</example>
+    public AnnotationOrigin Origin { get; init; } = AnnotationOrigin.BottomLeft;
+
+    /// <summary>
+    /// Text content (required for Text stamps)
+    /// </summary>
+    /// <example>"CONFIDENTIAL"</example>
+    public string? Text { get; init; }
+
+    /// <summary>
+    /// Font name (default: Arial)
+    /// </summary>
+    /// <example>"Arial"</example>
+    public string? FontName { get; init; }
+
+    /// <summary>
+    /// Font size in points (default: 12)
+    /// </summary>
+    /// <example>24.0</example>
+    public double? FontSize { get; init; }
+
+    /// <summary>
+    /// Hex color (6 digits, e.g., "FF0000" for red, default: "000000")
+    /// </summary>
+    /// <example>"FF0000"</example>
+    public string? Color { get; init; }
+
+    /// <summary>
+    /// Opacity (0.0 = transparent, 1.0 = opaque, default: 0.5)
+    /// </summary>
+    /// <example>0.5</example>
+    public double? Opacity { get; init; }
+
+    /// <summary>
+    /// Rotation angle in degrees (0-360, default: 0)
+    /// </summary>
+    /// <example>45.0</example>
+    public double? Rotation { get; init; }
+
+    /// <summary>
+    /// Stamp placement (Foreground = on top, Background = watermark effect, default: Foreground)
+    /// </summary>
+    /// <example>Foreground</example>
+    public StampPlacement Placement { get; init; } = StampPlacement.Foreground;
+
+    /// <summary>
+    /// Base64-encoded image (required for Image stamps, PNG/JPEG)
+    /// </summary>
+    /// <example>"iVBORw0KGgoAAAANSUhEUgAA..."</example>
+    public string? Base64Image { get; init; }
+
+    /// <summary>
+    /// Predefined stamp type (required for Predefined stamps)
+    /// </summary>
+    /// <example>Confidential</example>
+    public PredefinedStampType? PredefinedType { get; init; }
+}

DocumentOperator.API/Controllers/PdfValidationController.cs

@@ -1,9 +1,12 @@
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.ValidatePdf.Queries;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.ValidatePdf.Queries;
+using DocumentService.Application.ValidatePdfA.Queries;
+using DocumentService.Client.Models.Requests;
+using DocumentService.Domain.Common.Exceptions;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
 
-namespace DocumentOperator.API.Controllers;
+namespace DocumentService.API.Controllers;
 
 /// <summary>
 /// PDF validation operations
@@ -41,13 +44,11 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
             });
         }
 
-        // Convert IFormFile to byte array
-        using var memoryStream = new MemoryStream();
-        await file.CopyToAsync(memoryStream, cancellationToken);
-        byte[] pdfBytes = memoryStream.ToArray();
-
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+        
         // Direct pass-through to MediatR
-        var query = new ValidatePdfQuery { PdfBytes = pdfBytes };
+        var query = new ValidatePdfQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
         
         return Ok(result);
@@ -56,7 +57,7 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
     /// <summary>
     /// Validates a PDF document and returns metadata (Base64 JSON)
     /// </summary>
-    /// <param name="query">PDF as Base64 string</param>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>PDF metadata (page count, file size, PDF version, attachments)</returns>
     /// <response code="200">PDF is valid, metadata returned</response>
@@ -68,10 +69,100 @@ public class PdfValidationController(IMediator Mediator) : ControllerBase
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> ValidateFromBase64(
-        [FromBody] ValidatePdfQuery query,
+        [FromBody] ValidatePdfBase64Request request,
         CancellationToken cancellationToken)
     {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+        
         // Direct pass-through to MediatR
+        var query = new ValidatePdfQuery { PdfStream = pdfStream };
+        var result = await Mediator.Send(query, cancellationToken);
+        
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Validates a PDF/A document and checks conformance level (multipart/form-data)
+    /// </summary>
+    /// <param name="file">PDF file to validate</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>PDF/A metadata (conformance level, errors, warnings)</returns>
+    /// <response code="200">PDF/A validation completed, results returned</response>
+    /// <response code="400">Invalid PDF or file format</response>
+    /// <response code="500">Internal server error during validation</response>
+    [HttpPost("validate-pdfa")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(PdfAValidationResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ValidatePdfAFromFile(
+        IFormFile file,
+        CancellationToken cancellationToken)
+    {
+        if (file == null || file.Length == 0)
+        {
+            return BadRequest(new ProblemDetails
+            {
+                Title = "Invalid file",
+                Detail = "File is required and cannot be empty",
+                Status = StatusCodes.Status400BadRequest
+            });
+        }
+
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+        
+        // Direct pass-through to MediatR
+        var query = new ValidatePdfAQuery { PdfStream = pdfStream };
+        var result = await Mediator.Send(query, cancellationToken);
+        
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Validates a PDF/A document and checks conformance level (Base64 JSON)
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>PDF/A metadata (conformance level, errors, warnings)</returns>
+    /// <response code="200">PDF/A validation completed, results returned</response>
+    /// <response code="400">Invalid PDF or Base64 format</response>
+    /// <response code="500">Internal server error during validation</response>
+    [HttpPost("validate-pdfa")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(PdfAValidationResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ValidatePdfAFromBase64(
+        [FromBody] ValidatePdfABase64Request request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+        
+        // Direct pass-through to MediatR
+        var query = new ValidatePdfAQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
         
         return Ok(result);

DocumentOperator.API/Controllers/SwissQrCodeController.cs

@@ -1,9 +1,10 @@
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.SwissQrCode.Queries;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.SwissQrCode.Queries;
+using DocumentService.Domain.Common.Exceptions;
 using MediatR;
 using Microsoft.AspNetCore.Mvc;
 
-namespace DocumentOperator.API.Controllers;
+namespace DocumentService.API.Controllers;
 
 /// <summary>
 /// Swiss QR Code extraction operations
@@ -17,7 +18,7 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
     /// Extracts Swiss QR Code from the last page of a PDF document (multipart/form-data)
     /// </summary>
     /// <param name="file">PDF file containing Swiss QR Code</param>
-    /// <param name="references">Optional references (comma-separated)</param>
+    /// <param name="raw">If true, returns raw QR text lines instead of parsed Bill object</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>Swiss QR Code data (IBAN, amount, creditor, debtor, reference, etc.)</returns>
     /// <response code="200">Swiss QR Code extracted successfully</response>
@@ -32,44 +33,35 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> ExtractFromFile(
         IFormFile file,
-        [FromForm] string? references,
-        CancellationToken cancellationToken)
+        [FromQuery] bool raw = false,
+        CancellationToken cancellationToken = default)
     {
-        if (file == null || file.Length == 0)
-        {
+        if (file.Length == 0)
             return BadRequest(new ProblemDetails
             {
                 Title = "Invalid file",
                 Detail = "File is required and cannot be empty",
                 Status = StatusCodes.Status400BadRequest
             });
-        }
 
-        // Convert IFormFile to byte array
-        using var memoryStream = new MemoryStream();
-        await file.CopyToAsync(memoryStream, cancellationToken);
-        byte[] pdfBytes = memoryStream.ToArray();
-
-        // Parse references (comma-separated or empty)
-        var referencesList = string.IsNullOrWhiteSpace(references)
-            ? new List<string>()
-            : references.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries).ToList();
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
 
         // Direct pass-through to MediatR
         var query = new ExtractSwissQrCodeQuery 
         { 
-            PdfBytes = pdfBytes,
-            References = referencesList
+            PdfStream = pdfStream
         };
         var result = await Mediator.Send(query, cancellationToken);
 
-        return Ok(result);
+        return Ok(raw ? result.RawLines : result.Bill);
     }
 
     /// <summary>
     /// Extracts Swiss QR Code from the last page of a PDF document (Base64 JSON)
     /// </summary>
-    /// <param name="query">References array + PDF as Base64 string</param>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="raw">If true, returns raw QR text lines instead of parsed Bill object</param>
     /// <param name="cancellationToken">Cancellation token</param>
     /// <returns>Swiss QR Code data (IBAN, amount, creditor, debtor, reference, etc.)</returns>
     /// <response code="200">Swiss QR Code extracted successfully</response>
@@ -83,12 +75,39 @@ public class SwissQrCodeController(IMediator Mediator) : ControllerBase
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
     [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
     public async Task<IActionResult> ExtractFromBase64(
-        [FromBody] ExtractSwissQrCodeQuery query,
-        CancellationToken cancellationToken)
+        [FromBody] ExtractSwissQrCodeBase64Request request,
+        [FromQuery] bool raw = false,
+        CancellationToken cancellationToken = default)
     {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+        
         // Direct pass-through to MediatR
+        var query = new ExtractSwissQrCodeQuery { PdfStream = pdfStream };
         var result = await Mediator.Send(query, cancellationToken);
 
-        return Ok(result);
+        return Ok(raw ? result.RawLines : result.Bill);
     }
 }
+
+/// <summary>
+/// Request DTO for Base64-encoded Swiss QR Code extraction
+/// </summary>
+public record ExtractSwissQrCodeBase64Request
+{
+    /// <summary>
+    /// PDF document encoded as Base64 string
+    /// </summary>
+    /// <example>JVBERi0xLjQKJeLjz9MKMSAwIG9iago8PC9UeXBlL0NhdGFsb2c...</example>
+    public required string Base64Pdf { get; init; }
+}

DocumentOperator.API/Controllers/ZugferdController.cs

@@ -0,0 +1,179 @@
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.ExtractZugferd;
+using DocumentService.Application.HasZugferd.Queries;
+using DocumentService.Client.Models.Requests;
+using DocumentService.Domain.Common.Exceptions;
+using MediatR;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc;
+
+namespace DocumentService.API.Controllers;
+
+/// <summary>
+/// Controller for ZUGFeRD operations (detection, extraction)
+/// </summary>
+[ApiController]
+[Route("api/pdf/zugferd")]
+[Produces("application/json")]
+public class ZugferdController(IMediator mediator) : ControllerBase
+{
+    /// <summary>
+    /// Checks if a PDF contains ZUGFeRD XML attachment.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="file">The PDF file to check for ZUGFeRD</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>ZUGFeRD check result with metadata</returns>
+    /// <response code="200">PDF successfully checked - returns ZUGFeRD status</response>
+    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("has-zugferd")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(ZugferdCheckResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> HasZugferdFromFile(
+        IFormFile file,
+        CancellationToken cancellationToken)
+    {
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+
+        // Send query to MediatR (ValidationBehavior runs automatically)
+        var query = new HasZugferdQuery { PdfStream = pdfStream };
+        var result = await mediator.Send(query, cancellationToken);
+
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Checks if a PDF contains ZUGFeRD XML attachment.
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>ZUGFeRD check result with metadata</returns>
+    /// <response code="200">PDF successfully checked - returns ZUGFeRD status</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("has-zugferd")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(ZugferdCheckResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> HasZugferdFromBase64(
+        [FromBody] HasZugferdRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+        
+        // Send query to MediatR (ValidationBehavior runs automatically)
+        var query = new HasZugferdQuery { PdfStream = pdfStream };
+        var result = await mediator.Send(query, cancellationToken);
+
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Extracts ZUGFeRD XML from a PDF document.
+    /// Supports multipart/form-data file upload.
+    /// </summary>
+    /// <param name="file">The PDF file to extract ZUGFeRD from</param>
+    /// <param name="asFile">if true, 'file' (returns XML file directly); otherwise output format: 'json' (default, returns metadata + XML content)</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>ZUGFeRD XML content and metadata (JSON) or XML file (application/xml)</returns>
+    /// <response code="200">ZUGFeRD XML extracted successfully</response>
+    /// <response code="400">Invalid input (file missing, not a PDF, or corrupted)</response>
+    /// <response code="404">PDF contains no ZUGFeRD XML</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("extract")]
+    [Consumes("multipart/form-data")]
+    [ProducesResponseType(typeof(ZugferdExtractionResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ExtractZugferdFromFile(
+        IFormFile file,
+        [FromQuery] bool asFile = true,
+        CancellationToken cancellationToken = default)
+    {
+        // Use IFormFile stream directly (no intermediate byte[] conversion)
+        using var pdfStream = file.OpenReadStream();
+
+        // Send command to MediatR
+        var command = new ExtractZugferdCommand { PdfStream = pdfStream };
+        var result = await mediator.Send(command, cancellationToken);
+
+        // Return as file or JSON based on format parameter
+        if (asFile)
+        {
+            byte[] xmlBytes = System.Text.Encoding.UTF8.GetBytes(result.XmlContent);
+            return File(xmlBytes, "application/xml", result.FileName);
+        }
+
+        return Ok(result);
+    }
+
+    /// <summary>
+    /// Extracts ZUGFeRD XML from a PDF document.
+    /// Supports Base64-encoded PDF via JSON payload.
+    /// </summary>
+    /// <param name="request">Request containing Base64-encoded PDF</param>
+    /// <param name="format">Output format: 'json' (default, returns metadata + XML content) or 'file' (returns XML file directly)</param>
+    /// <param name="cancellationToken">Cancellation token</param>
+    /// <returns>ZUGFeRD XML content and metadata (JSON) or XML file (application/xml)</returns>
+    /// <response code="200">ZUGFeRD XML extracted successfully</response>
+    /// <response code="400">Invalid input (Base64 format error, not a PDF, or corrupted)</response>
+    /// <response code="404">PDF contains no ZUGFeRD XML</response>
+    /// <response code="500">Internal server error during PDF processing</response>
+    [HttpPost("extract")]
+    [Consumes("application/json")]
+    [ProducesResponseType(typeof(ZugferdExtractionResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(FileContentResult), StatusCodes.Status200OK)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status404NotFound)]
+    [ProducesResponseType(typeof(ProblemDetails), StatusCodes.Status500InternalServerError)]
+    public async Task<IActionResult> ExtractZugferdFromBase64(
+        [FromBody] ExtractZugferdRequest request,
+        [FromQuery] string format = "json",
+        CancellationToken cancellationToken = default)
+    {
+        // Convert Base64 to stream (wrap in try-catch to throw BadRequestException)
+        byte[] pdfBytes;
+        try
+        {
+            pdfBytes = Convert.FromBase64String(request.Base64Pdf);
+        }
+        catch (FormatException ex)
+        {
+            throw new BadRequestException("Invalid Base64 format: " + ex.Message);
+        }
+        
+        using var pdfStream = new MemoryStream(pdfBytes);
+
+        // Send command to MediatR
+        var command = new ExtractZugferdCommand { PdfStream = pdfStream };
+        var result = await mediator.Send(command, cancellationToken);
+
+        // Return as file or JSON based on format parameter
+        if (format.Equals("file", StringComparison.OrdinalIgnoreCase))
+        {
+            byte[] xmlBytes = System.Text.Encoding.UTF8.GetBytes(result.XmlContent);
+            return File(xmlBytes, "application/xml", result.FileName);
+        }
+
+        return Ok(result);
+    }
+}

DocumentOperator.API/DocumentOperator.API.csproj

@@ -1,25 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
-
-  <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
-    <Nullable>enable</Nullable>
-    <ImplicitUsings>enable</ImplicitUsings>
-	<GenerateDocumentationFile>true</GenerateDocumentationFile>
-  </PropertyGroup>
-
-  <ItemGroup>
-    <PackageReference Include="Asp.Versioning.Http" Version="8.1.1" />
-    <PackageReference Include="Microsoft.Extensions.Caching.StackExchangeRedis" Version="8.0.28" />
-    <PackageReference Include="Serilog.AspNetCore" Version="10.0.0" />
-    <PackageReference Include="Serilog.Enrichers.Environment" Version="3.0.1" />
-    <PackageReference Include="Serilog.Sinks.File" Version="7.0.0" />
-    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <ProjectReference Include="..\DocumentOperator.Application\DocumentOperator.Application.csproj" />
-    <ProjectReference Include="..\DocumentOperator.Domain\DocumentOperator.Domain.csproj" />
-    <ProjectReference Include="..\DocumentOperator.Infrastructure\DocumentOperator.Infrastructure.csproj" />
-  </ItemGroup>
-
-</Project>

DocumentOperator.API/DocumentOperator.API.http

@@ -1,6 +0,0 @@
-@DocumentOperator.API_HostAddress = http://localhost:5028
-
-GET {{DocumentOperator.API_HostAddress}}/weatherforecast/
-Accept: application/json
-
-###

DocumentOperator.API/DocumentService.API.csproj

@@ -0,0 +1,41 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <PackageId>DocumentOperator.API</PackageId>
+    <Authors>Digital Data GmbH</Authors>
+    <Company>Digital Data GmbH</Company>
+    <Product>DocumentOperator.API</Product>
+    <Version>1.0.0</Version>
+    <FileVersion>1.0.0.0</FileVersion>
+    <AssemblyVersion>1.0.0.0</AssemblyVersion>
+    <InformationalVersion>1.0.0</InformationalVersion>
+    <Copyright>Copyright © 2026 Digital Data GmbH. All rights reserved.</Copyright>
+    <Description>PDF Document Operations REST API - Validation, Swiss QR Code extraction, attachments, merge, annotation, stamp operations powered by DevExpress Office File API</Description>
+    <PackageTags>pdf document operator validation swiss-qr-code annotations stamp devexpress</PackageTags>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Asp.Versioning.Http" Version="8.1.1" />
+    <PackageReference Include="Microsoft.Extensions.Caching.StackExchangeRedis" Version="8.0.28" />
+    <PackageReference Include="Scalar.AspNetCore" Version="1.2.58" />
+    <PackageReference Include="Serilog.AspNetCore" Version="10.0.0" />
+    <PackageReference Include="Serilog.Enrichers.Environment" Version="3.0.1" />
+    <PackageReference Include="Serilog.Sinks.File" Version="7.0.0" />
+    <PackageReference Include="Serilog.Sinks.SQLite" Version="7.0.0" />
+    <PackageReference Include="Serilog.UI" Version="3.2.0" />
+    <PackageReference Include="Serilog.UI.SqliteProvider" Version="1.1.0" />
+    <PackageReference Include="Swashbuckle.AspNetCore" Version="6.6.2" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\DocumentOperator.Application\DocumentService.Application.csproj" />
+    <ProjectReference Include="..\DocumentOperator.Domain\DocumentService.Domain.csproj" />
+    <ProjectReference Include="..\DocumentOperator.Infrastructure\DocumentService.Infrastructure.csproj" />
+    <ProjectReference Include="..\DocumentService.Client\DocumentService.Client.csproj" />
+  </ItemGroup>
+
+</Project>

DocumentOperator.API/DocumentService.API.http

@@ -0,0 +1,6 @@
+@DocumentService.API_HostAddress = http://localhost:5028
+
+GET {{DocumentService.API_HostAddress}}/weatherforecast/
+Accept: application/json
+
+###

DocumentOperator.API/Middleware/ExceptionHandlingMiddleware.cs

@@ -1,31 +1,25 @@
-using DocumentOperator.Domain.Common.Exceptions;
-using DocumentOperator.Domain.Exceptions;
+using DocumentService.Domain.Common.Exceptions;
 using FluentValidation;
 using Microsoft.AspNetCore.Mvc;
 using System.Net;
 using System.Text.Json;
 
-namespace DocumentOperator.API.Middleware;
+namespace DocumentService.API.Middleware;
 
 /// <summary>
 /// Central exception handling middleware
 /// Maps exceptions to HTTP status codes and RFC 7807 Problem Details
 /// </summary>
-public class ExceptionHandlingMiddleware
+/// <remarks>
+/// Initializes a new instance of the <see cref="ExceptionHandlingMiddleware"/> class.
+/// </remarks>
+/// <param name="Next">The next middleware in the pipeline.</param>
+public class ExceptionHandlingMiddleware(RequestDelegate Next)
 {
-    private readonly RequestDelegate _next;
-    private readonly ILogger<ExceptionHandlingMiddleware> _logger;
-
-    /// <summary>
-    /// Initializes a new instance of the <see cref="ExceptionHandlingMiddleware"/> class.
-    /// </summary>
-    /// <param name="next">The next middleware in the pipeline.</param>
-    /// <param name="logger">The logger instance for exception logging.</param>
-    public ExceptionHandlingMiddleware(RequestDelegate next, ILogger<ExceptionHandlingMiddleware> logger)
+    private static readonly JsonSerializerOptions ProbDetailsJsonOpt = new()
     {
-        _next = next;
-        _logger = logger;
-    }
+        PropertyNamingPolicy = JsonNamingPolicy.CamelCase
+    };
 
     /// <summary>
     /// Invokes the middleware to handle incoming HTTP requests and catch exceptions.
@@ -35,11 +29,10 @@ public class ExceptionHandlingMiddleware
     {
         try
         {
-            await _next(context);
+            await Next(context);
         }
         catch (Exception ex)
         {
-            _logger.LogError(ex, "Unhandled exception: {ExceptionMessage}", ex.Message);
             await HandleExceptionAsync(context, ex);
         }
     }
@@ -51,12 +44,7 @@ public class ExceptionHandlingMiddleware
         context.Response.StatusCode = (int)statusCode;
         context.Response.ContentType = "application/problem+json";
 
-        var options = new JsonSerializerOptions
-        {
-            PropertyNamingPolicy = JsonNamingPolicy.CamelCase
-        };
-
-        await context.Response.WriteAsync(JsonSerializer.Serialize(problemDetails, options));
+        await context.Response.WriteAsync(JsonSerializer.Serialize(problemDetails, ProbDetailsJsonOpt));
     }
 
     private static (HttpStatusCode StatusCode, ProblemDetails ProblemDetails) MapExceptionToProblemDetails(
@@ -78,15 +66,15 @@ public class ExceptionHandlingMiddleware
                 }
             ),
 
-            // Domain Validation Exception (400 Bad Request)
-            DomainValidationException domainEx => (
+            // Bad Request Exception (400 Bad Request)
+            BadRequestException badReqEx => (
                 HttpStatusCode.BadRequest,
                 new ProblemDetails
                 {
-                    Type = "https://datatracker.ietf.org/doc/html/rfc7231#section-6.5.1",
-                    Title = "Domain Validation Error",
+                    Type = "https://datatracker.ietf.org/doc/html/rfc7231#section-6.5.4",
+                    Title = "Bad Request",
                     Status = (int)HttpStatusCode.BadRequest,
-                    Detail = domainEx.Message,
+                    Detail = badReqEx.Message,
                     Instance = context.Request.Path
                 }
             ),
@@ -104,32 +92,6 @@ public class ExceptionHandlingMiddleware
                 }
             ),
 
-            // Swiss QR Code Not Found Exception (404 Not Found)
-            SwissQrCodeNotFoundException qrNotFoundEx => (
-                HttpStatusCode.NotFound,
-                new ProblemDetails
-                {
-                    Type = "https://datatracker.ietf.org/doc/html/rfc7231#section-6.5.4",
-                    Title = "Swiss QR Code Not Found",
-                    Status = (int)HttpStatusCode.NotFound,
-                    Detail = qrNotFoundEx.Message,
-                    Instance = context.Request.Path
-                }
-            ),
-
-            // PDF Processing Exception (500 Internal Server Error)
-            PdfProcessingException pdfEx => (
-                HttpStatusCode.InternalServerError,
-                new ProblemDetails
-                {
-                    Type = "https://datatracker.ietf.org/doc/html/rfc7231#section-6.6.1",
-                    Title = "PDF Processing Error",
-                    Status = (int)HttpStatusCode.InternalServerError,
-                    Detail = pdfEx.Message,
-                    Instance = context.Request.Path
-                }
-            ),
-
             // Generic Exception (500 Internal Server Error)
             _ => (
                 HttpStatusCode.InternalServerError,

DocumentOperator.API/Middleware/RequestLoggingMiddleware.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.API.Middleware
+namespace DocumentService.API.Middleware
 {
     /// <summary>
     /// Placeholder middleware for HTTP request/response logging.

DocumentOperator.API/Middleware/TenantResolutionMiddleware.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.API.Middleware
+namespace DocumentService.API.Middleware
 {
     /// <summary>
     /// Placeholder middleware for multi-tenancy resolution via X-API-Key header.

DocumentOperator.API/PHASENPLAN.md

@@ -1,4 +1,4 @@
-# ?? DocumentOperator - Phasenplan (Feature-Driven Development)
+# ?? DocumentService - Phasenplan (Feature-Driven Development)
 
 > **Stand:** 17.01.2025 | **Aktuell:** Feature 3 - ExtractAttachments ? NEXT | **Projektdauer:** 6 Wochen
 
@@ -132,7 +132,7 @@
    - ? XML Comments aktiviert
 
 2. **XML-Dokumentation aktiviert**
-   - ? `API/DocumentOperator.API.csproj`
+   - ? `API/DocumentService.API.csproj`
    - ? `<GenerateDocumentationFile>true</GenerateDocumentationFile>`
 
 3. **Endpoint Dokumentation**
@@ -146,12 +146,12 @@
 
 5. **Program.cs Updates**
    - ? `builder.Services.AddSwaggerDocumentation()` statt `AddSwaggerGen()`
-   - ? `using DocumentOperator.API.Configuration;` hinzugefügt
+   - ? `using DocumentService.API.Configuration;` hinzugefügt
 
 **Akzeptanzkriterien:**
 - ? Build erfolgreich
 - ? Alle Tests grün (11/11)
-- ? XML-Dokumentation wird generiert (`DocumentOperator.API.xml`)
+- ? XML-Dokumentation wird generiert (`DocumentService.API.xml`)
 - ? Swagger UI zeigt Endpoint `/api/v1/documents/validate` mit Dokumentation
 - ? Request/Response-Schemas sind dokumentiert
 - ? Endpoint ist im Swagger UI testbar

DocumentOperator.API/Program.cs

@@ -1,9 +1,14 @@
 using Serilog;
-using DocumentOperator.Infrastructure.Configuration;
-using DocumentOperator.Application;
-using DocumentOperator.Infrastructure;
-using DocumentOperator.API.Middleware;
-using DocumentOperator.API.Configuration;
+using Serilog.Ui.Core.Extensions;
+using Serilog.Ui.SqliteDataProvider.Extensions;
+using Serilog.Ui.Web.Extensions;
+using Scalar.AspNetCore;
+using DocumentService.Infrastructure.Configuration;
+using DocumentService.Application;
+using DocumentService.Application.Common.Configuration;
+using DocumentService.Infrastructure;
+using DocumentService.API.Middleware;
+using DocumentService.API.Configuration;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -13,20 +18,23 @@ var builder = WebApplication.CreateBuilder(args);
 Log.Logger = new LoggerConfiguration()
     .ReadFrom.Configuration(builder.Configuration)
     .Enrich.FromLogContext()
-    .Enrich.WithProperty("Application", "DocumentOperator")
+    .Enrich.WithProperty("Application", "DocumentService")
     .CreateLogger();
 
 builder.Host.UseSerilog();
 
-Log.Information("Starting DocumentOperator API...");
+Log.Information("Starting DocumentService API...");
 
 try
 {
     // ========================================
     // 2. Options Pattern Configuration
     // ========================================
-    builder.Services.Configure<DocumentOperatorSettings>(
-        builder.Configuration.GetSection(DocumentOperatorSettings.SectionName));
+    builder.Services.Configure<DocumentServiceSettings>(
+        builder.Configuration.GetSection(DocumentServiceSettings.SectionName));
+
+    builder.Services.Configure<ZugferdSettings>(
+        builder.Configuration.GetSection("ZugferdSettings"));
 
     builder.Services.Configure<RedisSettings>(
         builder.Configuration.GetSection(RedisSettings.SectionName));
@@ -34,18 +42,37 @@ try
     builder.Services.Configure<ApiKeySettings>(
         builder.Configuration.GetSection(ApiKeySettings.SectionName));
 
+    builder.Services.Configure<SwaggerSettings>(
+        builder.Configuration.GetSection(SwaggerSettings.SectionName));
+
     // ========================================
     // 3. Services (Clean Architecture Layers)
     // ========================================
-    builder.Services.AddApplication();      // Application Layer (MediatR, FluentValidation, Behaviors)
+    builder.Services.AddApplication(builder.Configuration);      // Application Layer (MediatR, FluentValidation, Behaviors)
     builder.Services.AddInfrastructure();   // Infrastructure Layer (DevExpress, Services)
 
     builder.Services.AddControllers();      // Controllers (Controller-based API)
     builder.Services.AddEndpointsApiExplorer();
-    builder.Services.AddSwaggerDocumentation();
+    builder.Services.AddSwaggerDocumentation(builder.Configuration);
 
     // ========================================
-    // 4. Build App
+    // 4. Serilog.UI Configuration
+    // ========================================
+    var logDirectory = builder.Configuration.GetValue<string>("Application:LogDirectory")
+        ?? throw new InvalidOperationException("Application:LogDirectory not found in configuration.");
+    var sqliteDbPath = Path.Combine(logDirectory, "logs.db");
+
+    builder.Services.AddSerilogUi(logUIOpt =>
+    {
+        logUIOpt.UseSqliteServer(dbOpt =>
+        {
+            dbOpt.WithConnectionString($"Data Source={sqliteDbPath}");
+            dbOpt.WithTable("Logs");
+        });
+    });
+
+    // ========================================
+    // 5. Build App
     // ========================================
     var app = builder.Build();
 
@@ -56,10 +83,32 @@ try
     // Exception Handling FIRST (catches all exceptions from subsequent middleware)
     app.UseMiddleware<ExceptionHandlingMiddleware>();
 
-    if (app.Environment.IsDevelopment())
+    // ========================================
+    // Swagger/OpenAPI (Conditional based on settings)
+    // ========================================
+    var swaggerSettings = builder.Configuration.GetSection(SwaggerSettings.SectionName).Get<SwaggerSettings>()
+        ?? new SwaggerSettings();
+
+    if (app.Environment.IsDevelopment() || swaggerSettings.EnableInProduction)
     {
         app.UseSwagger();
-        app.UseSwaggerUI();
+        
+        // Swagger UI (classic)
+        app.UseSwaggerUI(options =>
+        {
+            options.SwaggerEndpoint($"/swagger/{swaggerSettings.Version}/swagger.json", 
+                $"{swaggerSettings.Title} {swaggerSettings.Version}");
+            options.RoutePrefix = "swagger"; // /swagger
+        });
+
+        // Scalar UI (modern alternative)
+        app.MapScalarApiReference(options =>
+        {
+            options
+                .WithTitle(swaggerSettings.Title)
+                .WithTheme(ScalarTheme.DeepSpace)
+                .WithDefaultHttpClient(ScalarTarget.CSharp, ScalarClient.HttpClient);
+        });
     }
 
     app.UseSerilogRequestLogging(); // Log HTTP Requests
@@ -67,11 +116,16 @@ try
     app.UseHttpsRedirection();
 
     // ========================================
-    // 6. Endpoints (Controller-based API)
+    // 6. Serilog.UI Dashboard
+    // ========================================
+    app.UseSerilogUi(); // Accessible at /serilog-ui
+
+    // ========================================
+    // 7. Endpoints (Controller-based API)
     // ========================================
     app.MapControllers(); // Maps all [ApiController] controllers
 
-    Log.Information("DocumentOperator API started successfully");
+    Log.Information("DocumentService API started successfully");
 
     app.Run();
 }
@@ -87,7 +141,7 @@ finally
 
 // Make Program class accessible for Integration Tests
 /// <summary>
-/// Entry point class for the DocumentOperator API.
+/// Entry point class for the DocumentService API.
 /// Made partial and public for integration test access.
 /// </summary>
 public partial class Program { }

DocumentOperator.API/Properties/PublishProfiles/IISProfile.pubxml

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- https://go.microsoft.com/fwlink/?LinkID=208121. -->
+<Project>
+	<PropertyGroup>
+		<WebPublishMethod>Package</WebPublishMethod>
+		<LastUsedBuildConfiguration>Release</LastUsedBuildConfiguration>
+		<LastUsedPlatform>Any CPU</LastUsedPlatform>
+		<SiteUrlToLaunchAfterPublish />
+		<LaunchSiteAfterPublish>true</LaunchSiteAfterPublish>
+		<ExcludeApp_Data>false</ExcludeApp_Data>
+		<ProjectGuid>c60bc965-d293-ea64-b153-1941f0648df4</ProjectGuid>
+		<DesktopBuildPackageLocation>M:\App&amp;Service\0 DD - Smart UP\DocumentService\PreRelease\API\net8\$(Version)\DocumentService.API.zip</DesktopBuildPackageLocation>
+		<PackageAsSingleFile>true</PackageAsSingleFile>
+		<DeployIisAppPath>DocumentService.API</DeployIisAppPath>
+		<_TargetId>IISWebDeployPackage</_TargetId>
+		<TargetFramework>net8.0</TargetFramework>
+	</PropertyGroup>
+</Project>

DocumentOperator.API/README.md

@@ -0,0 +1,387 @@
+# DocumentService API - Manual Testing Guide
+
+This guide contains manual test scenarios for validating the DocumentService API endpoints using Swagger UI or tools like Postman.
+
+---
+
+## Prerequisites
+
+1. **Start the API:**
+   ```powershell
+   dotnet run --project DocumentService.API
+   ```
+   Default URL: `https://localhost:5001` (check console output for actual port)
+
+2. **Open Swagger UI:**
+   Navigate to `https://localhost:<port>/swagger`
+
+3. **Test PDFs:**
+   - Use PDFs from `fake-pdf/` folder (form.pdf, multi-page.pdf, one-page.pdf, with-image.pdf)
+   - Or use your own PDF files
+
+---
+
+## Feature 1: Basic PDF Validation
+
+### Endpoint: `POST /api/pdf/validation/validate`
+
+#### Test Case 1.1: Valid PDF (Multipart Upload)
+**Objective:** Verify basic PDF validation works with file upload
+
+**Steps:**
+1. Open Swagger UI → `/api/pdf/validation/validate`
+2. Click "Try it out"
+3. Select **multipart/form-data** from dropdown
+4. Click "Choose File" and select `fake-pdf/one-page.pdf`
+5. Click "Execute"
+
+**Expected Result:**
+- **Status Code:** 200 OK
+- **Response Body:**
+  ```json
+  {
+    "pageCount": 1,
+    "fileSizeBytes": 7168,
+    "fileSizeMB": 0.01,
+    "pdfVersion": "1.4",
+    "hasAttachments": false,
+    "attachmentCount": 0
+  }
+  ```
+
+---
+
+#### Test Case 1.2: Valid PDF (Base64 JSON)
+**Objective:** Verify Base64 input works
+
+**Steps:**
+1. Convert a PDF to Base64:
+   ```powershell
+   $bytes = [System.IO.File]::ReadAllBytes("fake-pdf/one-page.pdf")
+   $base64 = [Convert]::ToBase64String($bytes)
+   Write-Output $base64
+   ```
+2. Open Swagger UI → `/api/pdf/validation/validate`
+3. Click "Try it out"
+4. Select **application/json** from dropdown
+5. Paste into Request Body:
+   ```json
+   {
+     "base64Pdf": "<paste-your-base64-here>"
+   }
+   ```
+6. Click "Execute"
+
+**Expected Result:**
+- **Status Code:** 200 OK
+- Same response as Test 1.1
+
+---
+
+#### Test Case 1.3: Invalid Base64 String
+**Objective:** Verify validation rejects malformed Base64
+
+**Steps:**
+1. Open Swagger UI → `/api/pdf/validation/validate`
+2. Select **application/json**
+3. Paste into Request Body:
+   ```json
+   {
+     "base64Pdf": "invalid-base64!!!"
+   }
+   ```
+4. Click "Execute"
+
+**Expected Result:**
+- **Status Code:** 400 Bad Request
+- **Error Message:** Contains "Base64"
+
+---
+
+#### Test Case 1.4: Empty File Upload
+**Objective:** Verify empty files are rejected
+
+**Steps:**
+1. Create an empty file (`empty.pdf`)
+2. Upload via multipart/form-data
+
+**Expected Result:**
+- **Status Code:** 400 Bad Request
+- **Error Message:** Contains "cannot be empty"
+
+---
+
+#### Test Case 1.5: Large Multi-Page PDF
+**Objective:** Verify handling of larger PDFs
+
+**Steps:**
+1. Upload `fake-pdf/multi-page.pdf` (49 KB)
+
+**Expected Result:**
+- **Status Code:** 200 OK
+- **Response:**
+  ```json
+  {
+    "pageCount": 3,
+    "fileSizeBytes": 49152,
+    "fileSizeMB": 0.05,
+    "pdfVersion": "1.7",
+    "hasAttachments": false,
+    "attachmentCount": 0
+  }
+  ```
+
+---
+
+#### Test Case 1.6: PDF with Images
+**Objective:** Verify image-heavy PDFs are processed
+
+**Steps:**
+1. Upload `fake-pdf/with-image.pdf` (256 KB)
+
+**Expected Result:**
+- **Status Code:** 200 OK
+- **Response:**
+  ```json
+  {
+    "pageCount": 1,
+    "fileSizeBytes": 262144,
+    "fileSizeMB": 0.25,
+    "pdfVersion": "1.6",
+    "hasAttachments": false,
+    "attachmentCount": 0
+  }
+  ```
+
+---
+
+## Feature 3: PDF/A Validation
+
+### Endpoint: `POST /api/pdf/validation/validate-pdfa`
+
+#### Test Case 3.1: PDF/A Compliant Document (Multipart)
+**Objective:** Verify PDF/A validation detects conformance
+
+**Steps:**
+1. Open Swagger UI → `/api/pdf/validation/validate-pdfa`
+2. Select **multipart/form-data**
+3. Upload a PDF/A-compliant PDF (if available)
+4. Click "Execute"
+
+**Expected Result (if PDF/A compliant):**
+- **Status Code:** 200 OK
+- **Response:**
+  ```json
+  {
+    "isValid": true,
+    "pdfVersion": "1.7",
+    "pageCount": 1,
+    "fileSize": 12345,
+    "encrypted": false,
+    "pdfAVersion": "PDF/A-3b",
+    "pdfACompliant": true,
+    "errors": [],
+    "warnings": []
+  }
+  ```
+
+---
+
+#### Test Case 3.2: Non-PDF/A Document
+**Objective:** Verify regular PDFs are detected as non-compliant
+
+**Steps:**
+1. Upload `fake-pdf/one-page.pdf` (regular PDF, NOT PDF/A)
+
+**Expected Result:**
+- **Status Code:** 200 OK
+- **Response:**
+  ```json
+  {
+    "isValid": true,
+    "pdfVersion": "1.4",
+    "pageCount": 1,
+    "fileSize": 7168,
+    "encrypted": false,
+    "pdfAVersion": null,
+    "pdfACompliant": false,
+    "errors": [],
+    "warnings": ["Manual verification recommended: PDF/A compliance requires all fonts to be embedded"]
+  }
+  ```
+
+---
+
+#### Test Case 3.3: Encrypted PDF
+**Objective:** Verify encrypted PDFs are flagged
+
+**Steps:**
+1. Create or obtain a password-protected PDF
+2. Upload via multipart/form-data
+
+**Expected Result:**
+- **Status Code:** 200 OK
+- **Response:**
+  ```json
+  {
+    "isValid": true,
+    "pdfVersion": "1.7",
+    "pageCount": 1,
+    "fileSize": 12345,
+    "encrypted": true,
+    "pdfAVersion": null,
+    "pdfACompliant": false,
+    "errors": ["Encrypted PDFs cannot be PDF/A compliant"],
+    "warnings": []
+  }
+  ```
+
+---
+
+#### Test Case 3.4: Invalid Base64 (PDF/A Endpoint)
+**Objective:** Verify validation works on PDF/A endpoint
+
+**Steps:**
+1. Select **application/json**
+2. Paste:
+   ```json
+   {
+     "base64Pdf": "not-base64!!!"
+   }
+   ```
+
+**Expected Result:**
+- **Status Code:** 400 Bad Request
+- **Error Message:** Contains "Base64"
+
+---
+
+#### Test Case 3.5: Empty Request
+**Objective:** Verify both inputs missing is rejected
+
+**Steps:**
+1. Select **application/json**
+2. Paste:
+   ```json
+   {
+     "pdfBytes": null,
+     "base64Pdf": ""
+   }
+   ```
+
+**Expected Result:**
+- **Status Code:** 400 Bad Request
+- **Error Message:** "Either PdfBytes or Base64Pdf must be provided, but not both"
+
+---
+
+## Feature 2: Swiss QR Code Extraction
+
+### Endpoint: `POST /api/swissqrcode/extract`
+
+#### Test Case 2.1: PDF with Swiss QR Code
+**Objective:** Extract Swiss QR Bill from PDF
+
+**Steps:**
+1. Open Swagger UI → `/api/swissqrcode/extract`
+2. Select **multipart/form-data**
+3. Upload a PDF containing Swiss QR Code on the **last page**
+4. Click "Execute"
+
+**Expected Result (if QR code present):**
+- **Status Code:** 200 OK
+- **Response:** Contains Swiss QR Bill details (IBAN, amount, creditor, debtor, reference)
+
+---
+
+#### Test Case 2.2: PDF without QR Code
+**Objective:** Verify graceful handling when no QR code exists
+
+**Steps:**
+1. Upload `fake-pdf/one-page.pdf` (no QR code)
+
+**Expected Result:**
+- **Status Code:** 404 Not Found
+- **Error Message:** "Swiss QR Code not found in PDF"
+
+---
+
+## Common Error Scenarios
+
+### Test Case E1: Missing File in Multipart Request
+**Steps:**
+1. Any multipart endpoint
+2. Don't select a file, click "Execute"
+
+**Expected Result:**
+- **Status Code:** 400 Bad Request
+
+---
+
+### Test Case E2: Both PdfBytes AND Base64Pdf Provided
+**Steps:**
+1. Attempt to send JSON with both fields populated
+   ```json
+   {
+     "pdfBytes": [1,2,3],
+     "base64Pdf": "dGVzdA=="
+   }
+   ```
+
+**Expected Result:**
+- **Status Code:** 400 Bad Request
+- **Error Message:** "Either PdfBytes or Base64Pdf must be provided, but not both"
+
+---
+
+### Test Case E3: Corrupted PDF File
+**Steps:**
+1. Create a text file with `.pdf` extension containing "FAKE PDF CONTENT"
+2. Upload it
+
+**Expected Result:**
+- **Status Code:** 500 Internal Server Error
+- **Error Message:** Contains "PDF processing error"
+
+---
+
+## Test Coverage Summary
+
+| Feature | Endpoint | Test Cases |
+|---------|----------|------------|
+| Basic PDF Validation | `POST /api/pdf/validation/validate` | 6 |
+| PDF/A Validation | `POST /api/pdf/validation/validate-pdfa` | 5 |
+| Swiss QR Code | `POST /api/swissqrcode/extract` | 2 |
+| Error Handling | All endpoints | 3 |
+| **TOTAL** | | **16 Manual Test Cases** |
+
+---
+
+## Notes
+
+- All endpoints support **BOTH** `multipart/form-data` (file upload) AND `application/json` (Base64)
+- FluentValidation runs before handlers (400 errors indicate validation failures)
+- DevExpress evaluation warnings (DX1000/DX1001) are expected and can be ignored
+- Test PDFs in `fake-pdf/` folder are small samples; use real-world PDFs for comprehensive testing
+
+---
+
+## Quick PowerShell Helpers
+
+**Convert PDF to Base64:**
+```powershell
+$bytes = [System.IO.File]::ReadAllBytes("path\to\file.pdf")
+$base64 = [Convert]::ToBase64String($bytes)
+$base64 | Set-Clipboard  # Copies to clipboard
+```
+
+**Create empty PDF for testing:**
+```powershell
+New-Item -Path "empty.pdf" -ItemType File -Force
+```
+
+**Check if file is valid PDF:**
+```powershell
+$header = Get-Content -Path "file.pdf" -TotalCount 1 -Encoding Byte
+# Should start with: 0x25 0x50 0x44 0x46 (%PDF)
+```

DocumentOperator.API/appsettings.Development.json

@@ -5,8 +5,8 @@
     }
   },
 
-  "DocumentOperatorSettings": {
-    "TempFolderPath": "C:\\Temp\\DocumentOperator\\Dev",
+  "DocumentServiceSettings": {
+    "TempFolderPath": "C:\\Temp\\DocumentService\\Dev",
     "EnableDetailedLogging": true
   },
 

DocumentOperator.API/appsettings.json

@@ -7,6 +7,17 @@
   },
   "AllowedHosts": "*",
 
+  "Application": {
+    "LogDirectory": "E:\\LogFiles\\Digital Data\\DocumentService.API"
+  },
+
+  "SwaggerSettings": {
+    "EnableInProduction": true,
+    "Title": "DocumentService API",
+    "Version": "v1",
+    "Description": "PDF document processing service using DevExpress"
+  },
+
   "Serilog": {
     "MinimumLevel": {
       "Default": "Information",
@@ -30,21 +41,45 @@
           "rollingInterval": "Day",
           "outputTemplate": "{Timestamp:yyyy-MM-dd HH:mm:ss.fff zzz} [{Level:u3}] {Message:lj} {Properties:j}{NewLine}{Exception}"
         }
+      },
+      {
+        "Name": "SQLite",
+        "Args": {
+          "sqliteDbPath": "E:\\LogFiles\\Digital Data\\DocumentService.API\\logs.db",
+          "tableName": "Logs",
+          "storeTimestampInUtc": true
+        }
       }
     ],
     "Enrich": [ "FromLogContext", "WithMachineName", "WithThreadId" ]
   },
 
-  "DocumentOperatorSettings": {
-    "TempFolderPath": "C:\\Temp\\DocumentOperator",
+  "DocumentServiceSettings": {
+    "TempFolderPath": "C:\\Temp\\DocumentService",
     "TempFileRetentionHours": 24,
     "MaxPdfSizeMB": 50,
     "EnableDetailedLogging": true
   },
 
+  "ZugferdSettings": {
+    "ZugferdFileNames": [
+      "factur-x.xml",
+      "zugferd-invoice.xml",
+      "ZUGFeRD-invoice.xml",
+      "xrechnung.xml",
+      "XRechnung.xml"
+    ],
+    "ZugferdFileNamePatterns": [
+      "factur",
+      "zugferd",
+      "xrechnung",
+      "peppol"
+    ]
+  },
+
   "RedisSettings": {
     "ConnectionString": "localhost:6379",
-    "InstanceName": "DocumentOperator:",
+    "InstanceName": "DocumentService:",
     "CacheExpirationMinutes": 60
   },
 
@@ -62,5 +97,6 @@
         "IsActive": true
       }
     }
-  }
+  },
+  "LuckyPennySoftLicenseKey": "eyJhbGciOiJSUzI1NiIsImtpZCI6Ikx1Y2t5UGVubnlTb2Z0d2FyZUxpY2Vuc2VLZXkvYmJiMTNhY2I1OTkwNGQ4OWI0Y2IxYzg1ZjA4OGNjZjkiLCJ0eXAiOiJKV1QifQ.eyJpc3MiOiJodHRwczovL2x1Y2t5cGVubnlzb2Z0d2FyZS5jb20iLCJhdWQiOiJMdWNreVBlbm55U29mdHdhcmUiLCJleHAiOiIxODE2MTI4MDAwIiwiaWF0IjoiMTc4NDYyNDU1NyIsImFjY291bnRfaWQiOiIwMTk4M2M1OWU0YjM3MjhlYmZkMzEwM2MyYTQ4NmU4NSIsImN1c3RvbWVyX2lkIjoiMDE5ODNjNTllNGIzNzI4ZWJmZDMxMDNjMmE0ODZlODUiLCJzdWJfaWQiOiItIiwiZWRpdGlvbiI6IjAiLCJ0eXBlIjoiMiJ9.IUUO926m9crYGYxMjjKD_n9BnUm-EDyjFIn0YmMUCo7C-QTwvB8WhXP8veTSFsBq-leIIDJ4jyl7Pgc_7ciwg1XhUSIs4mkQroEUaSFCGOxw7Pi41WM8MK5YFSaqLTYYXec9zxgiJbGzABbh3CHTSup3okGnVm_CMoPEs91l2c0A6N1JyZy74urd_tF0KGVKf0MOvzdlQIWLQ8o73S4pTv2N-F6UlzI0fdMtTHMLNNQyr0NdWdnuBk_jMBXO-gy5RE_oCRfMTTYRX2n3XLK6pTfXE0Ct338o9F5sH8Ph2lTXSu56cpdsfZOQZGqCH0LoFp1Dd7RJgIgNmBiTGfvDnA"
 }

DocumentOperator.Application/AddAnnotation/AddAnnotationCommand.cs

@@ -0,0 +1,78 @@
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Domain.Models.ValueObjects;
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.AddAnnotation;
+
+/// <summary>
+/// Command to add an annotation to a PDF document.
+/// </summary>
+public record AddAnnotationCommand : IRequest<byte[]>
+{
+    public required Stream PdfStream { get; init; }
+    public required AnnotationType AnnotationType { get; init; }
+    public required int PageNumber { get; init; }
+    public required (double X1, double Y1, double X2, double Y2) Rectangle { get; init; }
+    public string? Content { get; init; }
+    public string? Author { get; init; }
+    public string? Color { get; init; }
+    public TextMarkupStyle? TextMarkupStyle { get; init; }
+    public AnnotationOrigin Origin { get; init; } = AnnotationOrigin.BottomLeft;
+}
+
+/// <summary>
+/// Handler for AddAnnotationCommand.
+/// </summary>
+public class AddAnnotationHandler(IPdfProcessor pdfProcessor) : IRequestHandler<AddAnnotationCommand, byte[]>
+{
+    public async Task<byte[]> Handle(AddAnnotationCommand request, CancellationToken cancellationToken)
+    {
+        return await pdfProcessor.AddAnnotationAsync(
+            request.PdfStream,
+            request.AnnotationType,
+            request.PageNumber,
+            request.Rectangle,
+            request.Content,
+            request.Author,
+            request.Color,
+            request.TextMarkupStyle,
+            request.Origin);
+    }
+}
+
+/// <summary>
+/// Validator for AddAnnotationCommand.
+/// </summary>
+public class AddAnnotationValidator : AbstractValidator<AddAnnotationCommand>
+{
+    public AddAnnotationValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+
+        RuleFor(x => x.PageNumber)
+            .GreaterThan(0)
+            .WithMessage("Page number must be greater than 0");
+
+        RuleFor(x => x.Content)
+            .NotEmpty()
+            .When(x => x.AnnotationType == AnnotationType.FreeText || x.AnnotationType == AnnotationType.StickyNote)
+            .WithMessage("Content is required for FreeText and StickyNote annotations");
+
+        RuleFor(x => x.TextMarkupStyle)
+            .NotNull()
+            .When(x => x.AnnotationType == AnnotationType.TextMarkup)
+            .WithMessage("TextMarkupStyle is required for TextMarkup annotations");
+
+        RuleFor(x => x.Color)
+            .Matches("^[0-9A-Fa-f]{6}$")
+            .When(x => !string.IsNullOrWhiteSpace(x.Color))
+            .WithMessage("Color must be a 6-digit hex value (e.g., 'FF0000' for red)");
+
+        RuleFor(x => x.Rectangle)
+            .Must(r => r.X2 > r.X1 && r.Y2 > r.Y1)
+            .WithMessage("Rectangle coordinates must define a valid area (X2 > X1 and Y2 > Y1)");
+    }
+}

DocumentOperator.Application/AddAttachments/AddAttachmentsCommand.cs

@@ -0,0 +1,90 @@
+using DocumentService.Application.Common.Interfaces;
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.AddAttachments;
+
+/// <summary>
+/// Command to add one or more attachments to a PDF document (supports PDF/A-3)
+/// </summary>
+public record AddAttachmentsCommand : IRequest<byte[]>
+{
+    /// <summary>
+    /// PDF document stream. Must be positioned at the beginning (Position = 0).
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+
+    /// <summary>
+    /// List of attachments to embed (filename, content, optional MIME type)
+    /// </summary>
+    public required IReadOnlyList<AttachmentFile> Attachments { get; init; }
+}
+
+/// <summary>
+/// Represents a file to be attached to a PDF
+/// </summary>
+public record AttachmentFile
+{
+    /// <summary>
+    /// File name (e.g., "invoice.xml", "document.pdf")
+    /// </summary>
+    public required string FileName { get; init; }
+
+    /// <summary>
+    /// File content as byte array
+    /// </summary>
+    public required byte[] Content { get; init; }
+
+    /// <summary>
+    /// MIME type (optional, e.g., "application/xml", "application/pdf")
+    /// If not provided, will be inferred from file extension
+    /// </summary>
+    public string? MimeType { get; init; }
+}
+
+/// <summary>
+/// Handler for AddAttachmentsCommand
+/// </summary>
+public class AddAttachmentsCommandHandler(IPdfProcessor pdfProcessor) 
+    : IRequestHandler<AddAttachmentsCommand, byte[]>
+{
+    public async Task<byte[]> Handle(AddAttachmentsCommand request, CancellationToken cancellationToken)
+    {
+        // Convert to tuple list for IPdfProcessor
+        var attachmentTuples = request.Attachments
+            .Select(a => (a.FileName, a.Content, a.MimeType))
+            .ToList();
+
+        return await pdfProcessor.AddAttachmentsAsync(request.PdfStream, attachmentTuples);
+    }
+}
+
+/// <summary>
+/// Validator for AddAttachmentsCommand
+/// </summary>
+public class AddAttachmentsCommandValidator : AbstractValidator<AddAttachmentsCommand>
+{
+    public AddAttachmentsCommandValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+
+        RuleFor(x => x.Attachments)
+            .NotNull()
+            .NotEmpty()
+            .WithMessage("At least one attachment is required");
+
+        RuleForEach(x => x.Attachments).ChildRules(attachment =>
+        {
+            attachment.RuleFor(a => a.FileName)
+                .NotEmpty()
+                .WithMessage("Attachment file name is required");
+
+            attachment.RuleFor(a => a.Content)
+                .NotNull()
+                .NotEmpty()
+                .WithMessage("Attachment content is required");
+        });
+    }
+}

DocumentOperator.Application/AddStamp/AddStampCommand.cs

@@ -0,0 +1,125 @@
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.AddStamp;
+
+/// <summary>
+/// Command to add a stamp (text, image, or predefined) to PDF pages.
+/// Combines Command, Handler, and Validator in a single file (Vertical Slice pattern).
+/// </summary>
+public record AddStampCommand : IRequest<byte[]>
+{
+    public required Stream PdfStream { get; init; }
+    public required Domain.Models.ValueObjects.StampType StampType { get; init; }
+    public int[]? PageNumbers { get; init; } // null = all pages
+    public required (double X, double Y) Position { get; init; }
+    public (double Width, double Height)? Size { get; init; }
+    public Domain.Models.ValueObjects.AnnotationOrigin Origin { get; init; } = Domain.Models.ValueObjects.AnnotationOrigin.BottomLeft;
+    public string? Text { get; init; }
+    public string? FontName { get; init; }
+    public double? FontSize { get; init; }
+    public string? Color { get; init; }
+    public double? Opacity { get; init; }
+    public double? Rotation { get; init; }
+    public Domain.Models.ValueObjects.StampPlacement Placement { get; init; } = Domain.Models.ValueObjects.StampPlacement.Foreground;
+    public byte[]? ImageBytes { get; init; }
+    public Domain.Models.ValueObjects.PredefinedStampType? PredefinedType { get; init; }
+}
+
+/// <summary>
+/// Handler for AddStampCommand.
+/// </summary>
+public class AddStampHandler(Common.Interfaces.IPdfProcessor pdfProcessor) : IRequestHandler<AddStampCommand, byte[]>
+{
+    public async Task<byte[]> Handle(AddStampCommand command, CancellationToken cancellationToken)
+    {
+        return await pdfProcessor.AddStampAsync(
+            command.PdfStream,
+            command.StampType,
+            command.PageNumbers,
+            command.Position,
+            command.Size,
+            command.Origin,
+            command.Text,
+            command.FontName,
+            command.FontSize,
+            command.Color,
+            command.Opacity,
+            command.Rotation,
+            command.Placement,
+            command.ImageBytes,
+            command.PredefinedType
+        );
+    }
+}
+
+/// <summary>
+/// Validator for AddStampCommand.
+/// </summary>
+public class AddStampValidator : AbstractValidator<AddStampCommand>
+{
+    public AddStampValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull().WithMessage("PDF stream is required");
+
+        RuleFor(x => x.Position.X)
+            .GreaterThanOrEqualTo(0).WithMessage("Position X must be >= 0");
+
+        RuleFor(x => x.Position.Y)
+            .GreaterThanOrEqualTo(0).WithMessage("Position Y must be >= 0");
+
+        // Text stamp validation
+        When(x => x.StampType == Domain.Models.ValueObjects.StampType.Text, () =>
+        {
+            RuleFor(x => x.Text)
+                .NotEmpty().WithMessage("Text is required for Text stamp type");
+        });
+
+        // Image stamp validation
+        When(x => x.StampType == Domain.Models.ValueObjects.StampType.Image, () =>
+        {
+            RuleFor(x => x.ImageBytes)
+                .NotNull().WithMessage("Image bytes are required for Image stamp type")
+                .Must(bytes => bytes != null && bytes.Length > 0).WithMessage("Image bytes cannot be empty");
+        });
+
+        // Predefined stamp validation
+        When(x => x.StampType == Domain.Models.ValueObjects.StampType.Predefined, () =>
+        {
+            RuleFor(x => x.PredefinedType)
+                .NotNull().WithMessage("Predefined type is required for Predefined stamp type");
+        });
+
+        // Optional parameter validations
+        When(x => x.Opacity.HasValue, () =>
+        {
+            RuleFor(x => x.Opacity!.Value)
+                .InclusiveBetween(0.0, 1.0).WithMessage("Opacity must be between 0.0 and 1.0");
+        });
+
+        When(x => x.Rotation.HasValue, () =>
+        {
+            RuleFor(x => x.Rotation!.Value)
+                .InclusiveBetween(0.0, 360.0).WithMessage("Rotation must be between 0 and 360 degrees");
+        });
+
+        When(x => x.FontSize.HasValue, () =>
+        {
+            RuleFor(x => x.FontSize!.Value)
+                .GreaterThan(0).WithMessage("Font size must be positive");
+        });
+
+        When(x => !string.IsNullOrWhiteSpace(x.Color), () =>
+        {
+            RuleFor(x => x.Color!)
+                .Matches(@"^[0-9A-Fa-f]{6}$").WithMessage("Color must be 6-digit hex (e.g., 'FF0000')");
+        });
+
+        When(x => x.PageNumbers != null, () =>
+        {
+            RuleFor(x => x.PageNumbers!)
+                .Must(pages => pages.All(p => p > 0)).WithMessage("All page numbers must be >= 1");
+        });
+    }
+}

DocumentOperator.Application/CheckPdfAttachments/Queries/CheckPdfAttachmentsQuery.cs

@@ -0,0 +1,37 @@
+using AutoMapper;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using MediatR;
+
+namespace DocumentService.Application.CheckPdfAttachments.Queries;
+
+/// <summary>
+/// Query for checking PDF attachments (Stream-based)
+/// </summary>
+public record CheckPdfAttachmentsQuery : IRequest<AttachmentCheckResult>
+{
+    /// <summary>
+    /// PDF as stream (caller is responsible for disposal)
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for CheckPdfAttachmentsQuery
+/// Orchestrates PDF attachment checking using IPdfProcessor and AutoMapper
+/// </summary>
+public class CheckPdfAttachmentsQueryHandler(IPdfProcessor PdfProcessor, IMapper Mapper)
+    : IRequestHandler<CheckPdfAttachmentsQuery, AttachmentCheckResult>
+{
+    /// <summary>
+    /// Checks PDF attachments and returns detailed metadata
+    /// </summary>
+    public async Task<AttachmentCheckResult> Handle(CheckPdfAttachmentsQuery request, CancellationToken cancellationToken)
+    {
+        // Call DevExpress service directly with stream (exceptions propagate naturally)
+        var attachmentInfo = await PdfProcessor.CheckAttachmentsAsync(request.PdfStream);
+
+        // Map DTO to response DTO using AutoMapper
+        return Mapper.Map<AttachmentCheckResult>(attachmentInfo);
+    }
+}

DocumentOperator.Application/CheckPdfAttachments/Queries/CheckPdfAttachmentsQueryValidator.cs

@@ -0,0 +1,18 @@
+using FluentValidation;
+
+namespace DocumentService.Application.CheckPdfAttachments.Queries;
+
+/// <summary>
+/// Validator for CheckPdfAttachmentsQuery
+/// Ensures PdfStream is not null
+/// </summary>
+public class CheckPdfAttachmentsQueryValidator : AbstractValidator<CheckPdfAttachmentsQuery>
+{
+    public CheckPdfAttachmentsQueryValidator()
+    {
+        // Rule: PdfStream must be provided and non-empty
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PdfStream is required");
+    }
+}

DocumentOperator.Application/Common/Behaviors/LoggingBehavior.cs

@@ -2,7 +2,7 @@ using MediatR;
 using Microsoft.Extensions.Logging;
 using System.Diagnostics;
 
-namespace DocumentOperator.Application.Common.Behaviors;
+namespace DocumentService.Application.Common.Behaviors;
 
 /// <summary>
 /// MediatR Pipeline Behavior that logs requests and tracks performance

DocumentOperator.Application/Common/Behaviors/ValidationBehavior.cs

@@ -1,7 +1,7 @@
 using FluentValidation;
 using MediatR;
 
-namespace DocumentOperator.Application.Common.Behaviors;
+namespace DocumentService.Application.Common.Behaviors;
 
 /// <summary>
 /// MediatR Pipeline Behavior that validates requests using FluentValidation

DocumentOperator.Application/Common/Configuration/ZugferdSettings.cs

@@ -0,0 +1,29 @@
+namespace DocumentService.Application.Common.Configuration;
+
+/// <summary>
+/// Configuration settings for ZUGFeRD/Factur-X/XRechnung detection
+/// </summary>
+public class ZugferdSettings
+{
+    /// <summary>
+    /// Exact ZUGFeRD/Factur-X/XRechnung file names to check (case-insensitive)
+    /// </summary>
+    public List<string> ZugferdFileNames { get; set; } = new()
+    {
+        "factur-x.xml",
+        "zugferd-invoice.xml",
+        "ZUGFeRD-invoice.xml",
+        "xrechnung.xml"
+    };
+    
+    /// <summary>
+    /// Partial filename patterns for ZUGFeRD detection (case-insensitive)
+    /// </summary>
+    public List<string> ZugferdFileNamePatterns { get; set; } = new()
+    {
+        "factur",
+        "zugferd",
+        "xrechnung",
+        "peppol"
+    };
+}

DocumentOperator.Application/Common/DTOs/AttachmentCheckResult.cs

@@ -0,0 +1,43 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// DTO for attachment check result returned to API layer
+/// </summary>
+public record AttachmentCheckResult
+{
+    /// <summary>
+    /// Indicates whether the PDF contains any attachments
+    /// </summary>
+    public bool HasAttachments { get; init; }
+
+    /// <summary>
+    /// Total number of attachments in the PDF
+    /// </summary>
+    public int AttachmentCount { get; init; }
+
+    /// <summary>
+    /// List of attachment metadata (file details)
+    /// </summary>
+    public List<AttachmentDto> Attachments { get; init; } = new();
+}
+
+/// <summary>
+/// DTO for individual attachment metadata
+/// </summary>
+public record AttachmentDto
+{
+    /// <summary>
+    /// Attachment file name (e.g., "invoice.xml", "document.pdf")
+    /// </summary>
+    public string FileName { get; init; } = string.Empty;
+
+    /// <summary>
+    /// MIME type of the attachment (e.g., "text/xml", "application/pdf")
+    /// </summary>
+    public string MimeType { get; init; } = string.Empty;
+
+    /// <summary>
+    /// Attachment file size in bytes
+    /// </summary>
+    public long Size { get; init; }
+}

DocumentOperator.Application/Common/DTOs/AttachmentInfo.cs

@@ -0,0 +1,60 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Represents complete attachment information for a PDF document.
+/// Immutable value object containing attachment presence flag, count, and detailed metadata.
+/// </summary>
+public sealed class AttachmentInfo
+{
+    /// <summary>
+    /// Gets a value indicating whether the PDF contains any attachments
+    /// </summary>
+    public bool HasAttachments { get; }
+
+    /// <summary>
+    /// Gets the total number of attachments in the PDF
+    /// </summary>
+    public int AttachmentCount { get; }
+
+    /// <summary>
+    /// Gets the collection of attachment metadata (file details)
+    /// </summary>
+    public IReadOnlyList<AttachmentMetadata> Attachments { get; }
+
+    /// <summary>
+    /// Initializes a new instance of the AttachmentInfo class.
+    /// </summary>
+    /// <param name="hasAttachments">Whether PDF has attachments</param>
+    /// <param name="attachmentCount">Total number of attachments</param>
+    /// <param name="attachments">List of attachment metadata (can be empty)</param>
+    public AttachmentInfo(bool hasAttachments, int attachmentCount, IReadOnlyList<AttachmentMetadata> attachments)
+    {
+        HasAttachments = hasAttachments;
+        AttachmentCount = attachmentCount;
+        Attachments = attachments ?? [];
+
+        // Defensive Programming: Ensure count matches list length
+        if (Attachments.Count != attachmentCount)
+        {
+            throw new ArgumentException(
+                $"Attachment count mismatch: expected {attachmentCount}, got {Attachments.Count}",
+                nameof(attachments));
+        }
+    }
+
+    /// <summary>
+    /// Creates an AttachmentInfo instance for a PDF with no attachments.
+    /// </summary>
+    public static AttachmentInfo Empty =>
+        new(
+            hasAttachments: false,
+            attachmentCount: 0,
+            attachments: []);
+
+    public override string ToString()
+    {
+        return HasAttachments
+            ? $"PDF has {AttachmentCount} attachment(s): {string.Join(", ", Attachments.Select(a => a.FileName))}"
+            : "PDF has no attachments";
+    }
+}

DocumentOperator.Application/Common/DTOs/AttachmentMetadata.cs

@@ -0,0 +1,44 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Represents metadata of a single PDF attachment (embedded file).
+/// Immutable value object containing file information without the actual binary data.
+/// </summary>
+/// <remarks>
+/// Initializes a new instance of the AttachmentMetadata class.
+/// </remarks>
+/// <param name="fileName">Attachment file name</param>
+/// <param name="mimeType">MIME type (e.g., "text/xml")</param>
+/// <param name="sizeBytes">File size in bytes</param>
+public sealed class AttachmentMetadata(string fileName, string mimeType, long sizeBytes)
+{
+    /// <summary>
+    /// Gets the attachment file name (e.g., "invoice.xml", "document.pdf")
+    /// </summary>
+    public string FileName { get; } = fileName ?? string.Empty;
+
+    /// <summary>
+    /// Gets the MIME type of the attachment (e.g., "text/xml", "application/pdf")
+    /// </summary>
+    public string MimeType { get; } = mimeType ?? "application/octet-stream"; // Default MIME type if unknown
+
+    /// <summary>
+    /// Gets the attachment file size in bytes
+    /// </summary>
+    public long SizeBytes { get; } = sizeBytes;
+
+    /// <summary>
+    /// Gets the attachment file size in kilobytes (computed property)
+    /// </summary>
+    public double SizeKB => SizeBytes / 1024.0;
+
+    /// <summary>
+    /// Gets the attachment file size in megabytes (computed property)
+    /// </summary>
+    public double SizeMB => SizeBytes / 1024.0 / 1024.0;
+
+    public override string ToString()
+    {
+        return $"{FileName} ({MimeType}, {SizeKB:F2} KB)";
+    }
+}

DocumentOperator.Application/Common/DTOs/PdfAMetadata.cs

@@ -0,0 +1,34 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// PDF/A validation metadata including conformance level and validation errors/warnings
+/// </summary>
+public sealed class PdfAMetadata(
+    bool isValid,
+    string pdfVersion,
+    int pageCount,
+    long fileSizeBytes,
+    bool encrypted,
+    string? pdfaVersion,
+    bool pdfaCompliant,
+    IReadOnlyList<string> errors,
+    IReadOnlyList<string> warnings)
+{
+    public bool IsValid { get; } = isValid;
+    public string PdfVersion { get; } = pdfVersion;
+    public int PageCount { get; } = pageCount;
+    public long FileSizeBytes { get; } = fileSizeBytes;
+    public bool Encrypted { get; } = encrypted;
+    public string? PdfAVersion { get; } = pdfaVersion;
+    public bool PdfACompliant { get; } = pdfaCompliant;
+    public IReadOnlyList<string> Errors { get; } = errors;
+    public IReadOnlyList<string> Warnings { get; } = warnings;
+
+    // Computed property
+    public double FileSizeMB => FileSizeBytes / 1024.0 / 1024.0;
+
+    public override string ToString()
+    {
+        return $"PDF/A: {PdfAVersion ?? "None"}, {PageCount} pages, {FileSizeMB:F2} MB, Compliant: {PdfACompliant}";
+    }
+}

DocumentOperator.Application/Common/DTOs/PdfAValidationResult.cs

@@ -0,0 +1,52 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// PDF/A validation result including conformance level and validation errors/warnings
+/// </summary>
+public record PdfAValidationResult
+{
+    /// <summary>
+    /// Whether the PDF is valid (no errors)
+    /// </summary>
+    public bool IsValid { get; init; }
+
+    /// <summary>
+    /// PDF version (e.g., "1.4", "1.7")
+    /// </summary>
+    public string PdfVersion { get; init; } = string.Empty;
+
+    /// <summary>
+    /// Number of pages in the PDF
+    /// </summary>
+    public int PageCount { get; init; }
+
+    /// <summary>
+    /// File size in bytes
+    /// </summary>
+    public long FileSize { get; init; }
+
+    /// <summary>
+    /// Whether the PDF is encrypted
+    /// </summary>
+    public bool Encrypted { get; init; }
+
+    /// <summary>
+    /// PDF/A version (e.g., "PDF/A-1b", "PDF/A-2a", "PDF/A-3u") or null if not PDF/A compliant
+    /// </summary>
+    public string? PdfAVersion { get; init; }
+
+    /// <summary>
+    /// Whether the PDF conforms to PDF/A standard
+    /// </summary>
+    public bool PdfACompliant { get; init; }
+
+    /// <summary>
+    /// Validation errors (e.g., "PDF/A documents cannot be encrypted")
+    /// </summary>
+    public IReadOnlyList<string> Errors { get; init; } = [];
+
+    /// <summary>
+    /// Validation warnings (e.g., "Manual verification recommended: All fonts must be embedded")
+    /// </summary>
+    public IReadOnlyList<string> Warnings { get; init; } = [];
+}

DocumentOperator.Application/Common/DTOs/PdfMetadata.cs

@@ -0,0 +1,23 @@
+namespace DocumentService.Application.Common.DTOs;
+
+public sealed class PdfMetadata(
+    int pageCount,
+    long fileSizeBytes,
+    string pdfVersion,
+    bool hasAttachments,
+    int attachmentCount)
+{
+    public int PageCount { get; } = pageCount;
+    public long FileSizeBytes { get; } = fileSizeBytes;
+    public string PdfVersion { get; } = pdfVersion;
+    public bool HasAttachments { get; } = hasAttachments;
+    public int AttachmentCount { get; } = attachmentCount;
+
+    // Computed Property (berechnet aus FileSizeBytes)
+    public double FileSizeMB => FileSizeBytes / 1024.0 / 1024.0;
+
+    public override string ToString()
+    {
+        return $"PDF: {PageCount} pages, {FileSizeMB:F2} MB, Version {PdfVersion}, Attachments: {AttachmentCount}";
+    }
+}

DocumentOperator.Application/Common/DTOs/PdfValidationResult.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.Application.Common.DTOs;
+namespace DocumentService.Application.Common.DTOs;
 
 /// <summary>
 /// Response mit PDF-Metadaten

DocumentOperator.Application/Common/DTOs/SwissQrBillDto.cs

@@ -0,0 +1,93 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// Swiss QR Bill data transfer object (mapped from Codecrete Bill)
+/// </summary>
+public record SwissQrBillDto
+{
+    /// <summary>QR Bill standard version (e.g., "V2_0")</summary>
+    public required string Version { get; init; }
+
+    /// <summary>Payment amount (null if not specified)</summary>
+    public decimal? Amount { get; init; }
+
+    /// <summary>Payment currency (CHF or EUR)</summary>
+    public required string Currency { get; init; }
+
+    /// <summary>Creditor's IBAN account number</summary>
+    public required string Account { get; init; }
+
+    /// <summary>Creditor address</summary>
+    public required AddressDto Creditor { get; init; }
+
+    /// <summary>Payment reference type: "QRR", "SCOR", or "NON"</summary>
+    public required string ReferenceType { get; init; }
+
+    /// <summary>Payment reference (format depends on ReferenceType)</summary>
+    public string? Reference { get; init; }
+
+    /// <summary>Debtor address (optional)</summary>
+    public AddressDto? Debtor { get; init; }
+
+    /// <summary>Additional unstructured message (max 140 chars)</summary>
+    public string? UnstructuredMessage { get; init; }
+
+    /// <summary>Additional structured bill information</summary>
+    public string? BillInformation { get; init; }
+
+    /// <summary>Alternative payment schemes (max 2)</summary>
+    public IReadOnlyList<AlternativeSchemeDto>? AlternativeSchemes { get; init; }
+}
+
+/// <summary>
+/// Address data transfer object (mapped from Codecrete Address)
+/// </summary>
+public record AddressDto
+{
+    /// <summary>Address type: "Structured" or "CombinedElements"</summary>
+    public required string Type { get; init; }
+
+    /// <summary>Name of person or company</summary>
+    public required string Name { get; init; }
+
+    /// <summary>Street name (structured address only)</summary>
+    public string? Street { get; init; }
+
+    /// <summary>House number (structured address only)</summary>
+    public string? HouseNo { get; init; }
+
+    /// <summary>
+    /// Address line 1 (combined address only).
+    /// OBSOLETE: Use structured address instead. Will be removed when Codecrete v4 is adopted.
+    /// </summary>
+    [Obsolete("Use structured address (Street + HouseNo) instead. This field will be removed when upgrading to Codecrete.SwissQRBill.Generator v4.x")]
+    public string? AddressLine1 { get; init; }
+
+    /// <summary>
+    /// Address line 2 (combined address only).
+    /// OBSOLETE: Use structured address instead. Will be removed when Codecrete v4 is adopted.
+    /// </summary>
+    [Obsolete("Use structured address (Street + HouseNo) instead. This field will be removed when upgrading to Codecrete.SwissQRBill.Generator v4.x")]
+    public string? AddressLine2 { get; init; }
+
+    /// <summary>Postal code</summary>
+    public required string PostalCode { get; init; }
+
+    /// <summary>Town/city name</summary>
+    public required string Town { get; init; }
+
+    /// <summary>Two-letter country code (ISO 3166-1 alpha-2)</summary>
+    public required string CountryCode { get; init; }
+}
+
+/// <summary>
+/// Alternative payment scheme (mapped from Codecrete AlternativeScheme)
+/// </summary>
+public record AlternativeSchemeDto
+{
+    /// <summary>Scheme name (e.g., "AV1", "AV2")</summary>
+    public required string Name { get; init; }
+
+    /// <summary>Scheme instruction/parameter</summary>
+    public required string Instruction { get; init; }
+}

DocumentOperator.Application/Common/DTOs/SwissQrCodeExtractionResult.cs

@@ -1,116 +1,37 @@
-namespace DocumentOperator.Application.Common.DTOs;
+namespace DocumentService.Application.Common.DTOs;
 
 /// <summary>
-/// Response containing extracted Swiss QR Code data and passed-through references.
+/// Response containing extracted Swiss QR Code in dual format.
 /// </summary>
-/// <param name="References">Reference strings passed through from the request</param>
-/// <param name="QrCodeData">Parsed Swiss QR Code data from the last page of the PDF</param>
+/// <param name="Bill">Parsed Swiss QR Bill (structured format)</param>
+/// <param name="RawLines">Raw Swiss QR Code lines (original newline-separated format)</param>
 /// <example>
 /// {
-///   "references": ["REF-001", "REF-002"],
-///   "qrCodeData": {
-///     "qrType": "SPC",
-///     "version": "0200",
-///     "codingType": "1",
-///     "iban": "CH4431999123000889012",
-///     "creditor": {
-///       "addressType": "S",
-///       "name": "Robert Schneider AG",
-///       "street": "Rue du Lac",
-///       "buildingNumber": "1268",
-///       "postalCode": "2501",
-///       "city": "Biel",
-///       "country": "CH"
-///     },
-///     "amount": 1949.75,
+///   "bill": {
+///     "version": "V2_0",
+///     "amount": 630.20,
 ///     "currency": "CHF",
+///     "account": "CH953000520280564701R",
+///     "creditor": {
+///       "type": "Structured",
+///       "name": "ALMAT AG",
+///       "town": "Tagelswangen"
+///     },
 ///     "referenceType": "QRR",
-///     "reference": "210000000003139471430009017"
-///   }
+///     "reference": "000000000000000000252080824"
+///   },
+///   "rawLines": [
+///     "SPC",
+///     "0200",
+///     "1",
+///     "CH953000520280564701R",
+///     "S",
+///     "ALMAT AG",
+///     "..."
+///   ]
 /// }
 /// </example>
 public record SwissQrCodeExtractionResult(
-    IReadOnlyList<string> References,
-    SwissQrCodeDataDto QrCodeData
-);
-
-/// <summary>
-/// Swiss QR Code data according to Swiss QR Bill Standard 2.0.
-/// Contains all fields defined in the Swiss Payment Standards.
-/// </summary>
-public record SwissQrCodeDataDto(
-    /// <summary>QR type - always "SPC" for Swiss Payment Code</summary>
-    string QrType,
-
-    /// <summary>Version of the Swiss QR Code standard (e.g., "0200" for version 2.0)</summary>
-    string Version,
-
-    /// <summary>Character set code (always "1" for UTF-8)</summary>
-    string CodingType,
-
-    /// <summary>IBAN of the creditor (payee)</summary>
-    string Iban,
-
-    /// <summary>Creditor (payee) information</summary>
-    AddressDataDto Creditor,
-
-    /// <summary>Ultimate creditor information (optional)</summary>
-    AddressDataDto? UltimateCreditor,
-
-    /// <summary>Payment amount (null if not specified)</summary>
-    decimal? Amount,
-
-    /// <summary>Currency code (CHF or EUR)</summary>
-    string Currency,
-
-    /// <summary>Ultimate debtor (payer) information (optional)</summary>
-    AddressDataDto? UltimateDebtor,
-
-    /// <summary>Reference type: "QRR" (QR Reference), "SCOR" (Creditor Reference ISO 11649), or "NON" (No Reference)</summary>
-    string ReferenceType,
-
-    /// <summary>Payment reference (format depends on ReferenceType)</summary>
-    string? Reference,
-
-    /// <summary>Unstructured message (max 140 characters)</summary>
-    string? UnstructuredMessage,
-
-    /// <summary>Bill information (structured data for automated processing)</summary>
-    string? BillInformation,
-
-    /// <summary>Alternative procedure parameters (up to 2 entries)</summary>
-    IReadOnlyList<string>? AlternativeProcedureParameters
-);
-
-/// <summary>
-/// Address data in Swiss QR Code (creditor or debtor).
-/// Can be either structured (S) or combined (K) format.
-/// </summary>
-public record AddressDataDto(
-    /// <summary>Address type: "S" for structured, "K" for combined</summary>
-    string AddressType,
-
-    /// <summary>Name of person or company</summary>
-    string Name,
-
-    /// <summary>Street name (structured address only)</summary>
-    string? Street,
-
-    /// <summary>Building number (structured address only)</summary>
-    string? BuildingNumber,
-
-    /// <summary>Address line 1 (combined address only)</summary>
-    string? AddressLine1,
-
-    /// <summary>Address line 2 (combined address only)</summary>
-    string? AddressLine2,
-
-    /// <summary>Postal code</summary>
-    string PostalCode,
-
-    /// <summary>City/town name</summary>
-    string City,
-
-    /// <summary>Two-letter country code (ISO 3166-1 alpha-2)</summary>
-    string Country
+    SwissQrBillDto Bill,
+    IReadOnlyList<string> RawLines
 );

DocumentOperator.Application/Common/DTOs/ZugferdCheckResult.cs

@@ -0,0 +1,27 @@
+namespace DocumentService.Application.Common.DTOs;
+
+/// <summary>
+/// DTO for ZUGFeRD check result
+/// </summary>
+public record ZugferdCheckResult
+{
+    /// <summary>
+    /// Indicates whether the PDF contains ZUGFeRD XML attachment
+    /// </summary>
+    public bool HasZugferd { get; init; }
+
+    /// <summary>
+    /// ZUGFeRD XML file name (e.g., "factur-x.xml")
+    /// </summary>
+    public string? ZugferdFileName { get; init; }
+
+    /// <summary>
+    /// ZUGFeRD XML file size in bytes
+    /// </summary>
+    public long? ZugferdFileSize { get; init; }
+
+    /// <summary>
+    /// MIME type of the ZUGFeRD XML file
+    /// </summary>
+    public string? ZugferdMimeType { get; init; }
+}

DocumentOperator.Application/Common/Interfaces/IPdfProcessor.cs

@@ -1,16 +1,191 @@
-using DocumentOperator.Domain.Models.ValueObjects;
+using DocumentService.Application.Common.DTOs;
 
-namespace DocumentOperator.Application.Common.Interfaces;
+namespace DocumentService.Application.Common.Interfaces;
 
 public interface IPdfProcessor
 {
     /// <summary>
     /// Validates a PDF and extracts metadata.
     /// </summary>
-    /// <param name="pdfBytes">PDF content 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>
     /// <returns>PDF metadata (page count, size, version, attachments)</returns>
-    /// <exception cref="Domain.Common.Exceptions.PdfProcessingException">
-    /// Thrown when PDF is corrupted or cannot be processed
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when stream is empty, invalid, or not positioned at the beginning
     /// </exception>
-    Task<PdfMetadata> ValidateAsync(byte[] pdfBytes);
+    Task<PdfMetadata> ValidateAsync(Stream pdfStream);
+
+    /// <summary>
+    /// Validates a PDF/A document and checks conformance level.
+    /// </summary>
+    /// <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, 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 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, invalid, or not positioned at the beginning
+    /// </exception>
+    Task<AttachmentInfo> CheckAttachmentsAsync(Stream pdfStream);
+
+    /// <summary>
+    /// Extracts all embedded files from a PDF document and returns them as a ZIP archive.
+    /// </summary>
+    /// <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>ZIP archive containing all extracted attachments as byte array</returns>
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when stream is empty, invalid, or not positioned at the beginning
+    /// </exception>
+    /// <exception cref="Domain.Common.Exceptions.NotFoundException">
+    /// Thrown when PDF contains no attachments
+    /// </exception>
+    Task<byte[]> ExtractAttachmentsAsync(Stream pdfStream);
+
+    /// <summary>
+    /// Merges multiple PDF documents into a single PDF.
+    /// </summary>
+    /// <param name="pdfStreams">
+    /// PDF streams to merge (minimum 2 required). Each stream must be readable and positioned 
+    /// at the beginning (Position = 0). Caller is responsible for disposal.
+    /// </param>
+    /// <param name="pageRanges">
+    /// Optional page ranges per PDF (null = all pages). Format: "1-3,5" means pages 1, 2, 3, and 5.
+    /// If null or empty for a PDF, all pages are included. Array length must match pdfStreams length if provided.
+    /// </param>
+    /// <returns>Merged PDF as byte array</returns>
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when fewer than 2 PDFs provided, any stream is empty/invalid/not at Position=0, 
+    /// or page range format is invalid
+    /// </exception>
+    Task<byte[]> MergePdfsAsync(IReadOnlyList<Stream> pdfStreams, IReadOnlyList<string?>? pageRanges = null);
+
+    /// <summary>
+    /// Adds an annotation to a PDF document at the specified page and rectangle.
+    /// </summary>
+    /// <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="annotationType">Type of annotation to add (TextMarkup, FreeText, StickyNote, Circle, Square)</param>
+    /// <param name="pageNumber">Page number (1-based) where annotation should be added</param>
+    /// <param name="rectangle">Annotation bounding rectangle (X1, Y1, X2, Y2)</param>
+    /// <param name="content">Annotation content/comment text (required for FreeText and StickyNote)</param>
+    /// <param name="author">Optional author name</param>
+    /// <param name="color">Optional annotation color in RGB format (hex string like "FF0000" for red)</param>
+    /// <param name="textMarkupStyle">Text markup style (Highlight, Underline, Strikeout) - only for TextMarkup type</param>
+    /// <param name="origin">Coordinate origin (BottomLeft = PDF native, TopLeft = UI-friendly). Default: BottomLeft</param>
+    /// <returns>Annotated PDF as byte array</returns>
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when stream is empty/invalid/not at Position=0, page number out of range, 
+    /// rectangle invalid, or content missing for types that require it
+    /// </exception>
+    Task<byte[]> AddAnnotationAsync(
+        Stream pdfStream,
+        Domain.Models.ValueObjects.AnnotationType annotationType,
+        int pageNumber,
+        (double X1, double Y1, double X2, double Y2) rectangle,
+        string? content = null,
+        string? author = null,
+        string? color = null,
+        Domain.Models.ValueObjects.TextMarkupStyle? textMarkupStyle = null,
+        Domain.Models.ValueObjects.AnnotationOrigin origin = Domain.Models.ValueObjects.AnnotationOrigin.BottomLeft);
+
+    /// <summary>
+    /// Adds a stamp (text, image, or predefined) to specified pages of a PDF document.
+    /// </summary>
+    /// <param name="pdfStream">Input PDF stream (must support reading and seeking)</param>
+    /// <param name="stampType">Type of stamp (Text, Image, or Predefined)</param>
+    /// <param name="pageNumbers">Target page numbers (1-based). Null = all pages.</param>
+    /// <param name="position">Stamp position (X, Y coordinates)</param>
+    /// <param name="size">Stamp size (Width, Height). Null = auto-size for images.</param>
+    /// <param name="origin">Coordinate origin (BottomLeft or TopLeft)</param>
+    /// <param name="text">Text content (required for Text stamps)</param>
+    /// <param name="fontName">Font name (default: Arial)</param>
+    /// <param name="fontSize">Font size in points (default: 12)</param>
+    /// <param name="color">Hex color without # (e.g., "FF0000" for red, default: "000000")</param>
+    /// <param name="opacity">Opacity 0.0 (transparent) to 1.0 (opaque, default: 0.5)</param>
+    /// <param name="rotation">Rotation angle in degrees 0-360 (default: 0)</param>
+    /// <param name="placement">Foreground (on top) or Background (behind content)</param>
+    /// <param name="imageBytes">Image data (required for Image stamps, PNG/JPEG)</param>
+    /// <param name="predefinedType">Predefined stamp type (required for Predefined stamps)</param>
+    /// <returns>Stamped PDF as byte array</returns>
+    /// <exception cref="BadRequestException">Invalid parameters (missing text/image, invalid page numbers, invalid opacity/rotation)</exception>
+    /// <exception cref="PdfProcessingException">DevExpress processing error</exception>
+    Task<byte[]> AddStampAsync(
+        Stream pdfStream,
+        Domain.Models.ValueObjects.StampType stampType,
+        int[]? pageNumbers,
+        (double X, double Y) position,
+        (double Width, double Height)? size = null,
+        Domain.Models.ValueObjects.AnnotationOrigin origin = Domain.Models.ValueObjects.AnnotationOrigin.BottomLeft,
+        string? text = null,
+        string? fontName = null,
+        double? fontSize = null,
+        string? color = null,
+        double? opacity = null,
+        double? rotation = null,
+        Domain.Models.ValueObjects.StampPlacement placement = Domain.Models.ValueObjects.StampPlacement.Foreground,
+        byte[]? imageBytes = null,
+        Domain.Models.ValueObjects.PredefinedStampType? predefinedType = null);
+
+    /// <summary>
+    /// Embeds one or more files as attachments in a PDF document (supports PDF/A-3).
+    /// </summary>
+    /// <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="attachments">List of files to embed (filename, content, optional MIME type)</param>
+    /// <returns>PDF with embedded attachments as byte array</returns>
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when stream is empty/invalid, or attachments list is empty
+    /// </exception>
+    Task<byte[]> AddAttachmentsAsync(
+        Stream pdfStream, 
+        IReadOnlyList<(string FileName, byte[] Content, string? MimeType)> attachments);
+
+    /// <summary>
+    /// Converts a standard PDF to PDF/A format.
+    /// </summary>
+    /// <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="pdfALevel">Target PDF/A level (e.g., "PDF/A-1b", "PDF/A-2b", "PDF/A-3b")</param>
+    /// <returns>PDF/A compliant document as byte array</returns>
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when stream is empty/invalid or PDF/A level is unsupported
+    /// </exception>
+    Task<byte[]> ConvertToPdfAAsync(Stream pdfStream, string pdfALevel);
+
+    /// <summary>
+    /// Converts a PDF/A document to a standard PDF (removes PDF/A restrictions).
+    /// </summary>
+    /// <param name="pdfStream">
+    /// PDF/A document stream. Must be readable and positioned at the beginning (Position = 0).
+    /// Non-seekable streams are supported. Caller is responsible for disposal.
+    /// </param>
+    /// <returns>Standard PDF document as byte array</returns>
+    /// <exception cref="Domain.Common.Exceptions.BadRequestException">
+    /// Thrown when stream is empty/invalid
+    /// </exception>
+    Task<byte[]> ConvertFromPdfAAsync(Stream pdfStream);
 }

DocumentOperator.Application/Common/Interfaces/ISwissQrCodeProcessor.cs

@@ -1,6 +1,6 @@
-using DocumentOperator.Domain.ValueObjects;
+using Codecrete.SwissQRBill.Generator;
 
-namespace DocumentOperator.Application.Common.Interfaces;
+namespace DocumentService.Application.Common.Interfaces;
 
 /// <summary>
 /// Interface for Swiss QR Code processing operations.
@@ -9,16 +9,24 @@ namespace DocumentOperator.Application.Common.Interfaces;
 public interface ISwissQrCodeProcessor
 {
     /// <summary>
-    /// Extracts and parses Swiss QR Code from the last page of a PDF document.
+    /// 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>Parsed Swiss QR Code data</returns>
-    /// <exception cref="Domain.Exceptions.SwissQrCodeNotFoundException">
-    /// Thrown when no Swiss QR Code is found on the last page
+    /// <returns>Tuple: (Parsed Codecrete Bill, Raw QR lines as string array)</returns>
+    /// <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<SwissQrCodeData> ExtractSwissQrCodeAsync(byte[] pdfBytes, CancellationToken cancellationToken = default);
+    Task<(Bill Bill, string[] RawLines)> ExtractSwissQrCodeAsync(
+        Stream pdfStream, 
+        int[]? pageNumbers = null, 
+        CancellationToken cancellationToken = default);
 }

DocumentOperator.Application/Common/Mapping/MappingProfile.cs

@@ -1,12 +1,13 @@
 using AutoMapper;
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Domain.Models.ValueObjects;
-using DocumentOperator.Domain.ValueObjects;
+using Codecrete.SwissQRBill.Generator;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Domain.Models.ValueObjects;
 
-namespace DocumentOperator.Application.Common.Mapping;
+namespace DocumentService.Application.Common.Mapping;
 
 /// <summary>
-/// AutoMapper profile for mapping domain entities to DTOs
+/// AutoMapper profile for mapping domain entities and external models to DTOs.
+/// NOTE: Always use AutoMapper for all mappings in this project.
 /// </summary>
 public class MappingProfile : Profile
 {
@@ -15,10 +16,39 @@ public class MappingProfile : Profile
         // PdfMetadata -> PdfValidationResult
         CreateMap<PdfMetadata, PdfValidationResult>();
 
-        // SwissQrCodeData -> SwissQrCodeDataDto
-        CreateMap<SwissQrCodeData, SwissQrCodeDataDto>();
+        // PdfAMetadata -> PdfAValidationResult
+        CreateMap<PdfAMetadata, PdfAValidationResult>()
+            .ForMember(dest => dest.FileSize, opt => opt.MapFrom(src => src.FileSizeBytes));
 
-        // AddressData -> AddressDataDto
-        CreateMap<AddressData, AddressDataDto>();
+        // Codecrete Bill -> SwissQrBillDto
+        CreateMap<Bill, SwissQrBillDto>()
+            .ForMember(dest => dest.Version, opt => opt.MapFrom(src => src.Version.ToString()))
+            .ForMember(dest => dest.Currency, opt => opt.MapFrom(src => src.Currency ?? "CHF"))
+            .ForMember(dest => dest.Account, opt => opt.MapFrom(src => src.Account ?? string.Empty))
+            .ForMember(dest => dest.ReferenceType, opt => opt.MapFrom(src => src.ReferenceType ?? Bill.ReferenceTypeNoRef));
+
+        // Codecrete Address -> AddressDto
+        CreateMap<Address, AddressDto>()
+            .ForMember(dest => dest.Type, opt => opt.MapFrom(src => src.Type.ToString()))
+            .ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.Name ?? string.Empty))
+            .ForMember(dest => dest.PostalCode, opt => opt.MapFrom(src => src.PostalCode ?? string.Empty))
+            .ForMember(dest => dest.Town, opt => opt.MapFrom(src => src.Town ?? string.Empty))
+            .ForMember(dest => dest.CountryCode, opt => opt.MapFrom(src => src.CountryCode ?? string.Empty))
+#pragma warning disable CS0618 // Suppress obsolete warning for AddressLine1/2 mapping
+            .ForMember(dest => dest.AddressLine1, opt => opt.MapFrom(src => src.AddressLine1))
+            .ForMember(dest => dest.AddressLine2, opt => opt.MapFrom(src => src.AddressLine2));
+#pragma warning restore CS0618
+
+        // Codecrete AlternativeScheme -> AlternativeSchemeDto
+        CreateMap<AlternativeScheme, AlternativeSchemeDto>()
+            .ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.Name ?? string.Empty))
+            .ForMember(dest => dest.Instruction, opt => opt.MapFrom(src => src.Instruction ?? string.Empty));
+
+        // AttachmentInfo -> AttachmentCheckResult
+        CreateMap<AttachmentInfo, AttachmentCheckResult>();
+
+        // AttachmentMetadata -> AttachmentDto
+        CreateMap<AttachmentMetadata, AttachmentDto>()
+            .ForMember(dest => dest.Size, opt => opt.MapFrom(src => src.SizeBytes));
     }
 }

DocumentOperator.Application/ConvertFromPdfA/ConvertFromPdfACommand.cs

@@ -0,0 +1,41 @@
+using DocumentService.Application.Common.Interfaces;
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.ConvertFromPdfA;
+
+/// <summary>
+/// Command to convert a PDF/A document to a standard PDF (removes PDF/A restrictions)
+/// </summary>
+public record ConvertFromPdfACommand : IRequest<byte[]>
+{
+    /// <summary>
+    /// PDF/A document stream. Must be positioned at the beginning (Position = 0).
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for ConvertFromPdfACommand
+/// </summary>
+public class ConvertFromPdfACommandHandler(IPdfProcessor pdfProcessor) 
+    : IRequestHandler<ConvertFromPdfACommand, byte[]>
+{
+    public async Task<byte[]> Handle(ConvertFromPdfACommand request, CancellationToken cancellationToken)
+    {
+        return await pdfProcessor.ConvertFromPdfAAsync(request.PdfStream);
+    }
+}
+
+/// <summary>
+/// Validator for ConvertFromPdfACommand
+/// </summary>
+public class ConvertFromPdfACommandValidator : AbstractValidator<ConvertFromPdfACommand>
+{
+    public ConvertFromPdfACommandValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+    }
+}

DocumentOperator.Application/ConvertToPdfA/ConvertToPdfACommand.cs

@@ -0,0 +1,59 @@
+using DocumentService.Application.Common.Interfaces;
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.ConvertToPdfA;
+
+/// <summary>
+/// Command to convert a standard PDF to PDF/A format
+/// </summary>
+public record ConvertToPdfACommand : IRequest<byte[]>
+{
+    /// <summary>
+    /// PDF document stream. Must be positioned at the beginning (Position = 0).
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+
+    /// <summary>
+    /// Target PDF/A level (e.g., "PDF/A-1b", "PDF/A-2b", "PDF/A-3b")
+    /// </summary>
+    public required string PdfALevel { get; init; }
+}
+
+/// <summary>
+/// Handler for ConvertToPdfACommand
+/// </summary>
+public class ConvertToPdfACommandHandler(IPdfProcessor pdfProcessor) 
+    : IRequestHandler<ConvertToPdfACommand, byte[]>
+{
+    public async Task<byte[]> Handle(ConvertToPdfACommand request, CancellationToken cancellationToken)
+    {
+        return await pdfProcessor.ConvertToPdfAAsync(request.PdfStream, request.PdfALevel);
+    }
+}
+
+/// <summary>
+/// Validator for ConvertToPdfACommand
+/// </summary>
+public class ConvertToPdfACommandValidator : AbstractValidator<ConvertToPdfACommand>
+{
+    private static readonly string[] ValidPdfALevels = 
+    {
+        "PDF/A-1b", "PDF/A-1a",
+        "PDF/A-2b", "PDF/A-2u", "PDF/A-2a",
+        "PDF/A-3b", "PDF/A-3u", "PDF/A-3a"
+    };
+
+    public ConvertToPdfACommandValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+
+        RuleFor(x => x.PdfALevel)
+            .NotEmpty()
+            .WithMessage("PDF/A level is required")
+            .Must(level => ValidPdfALevels.Contains(level, StringComparer.OrdinalIgnoreCase))
+            .WithMessage($"Invalid PDF/A level. Valid values: {string.Join(", ", ValidPdfALevels)}");
+    }
+}

DocumentOperator.Application/DependencyInjection.cs

@@ -1,7 +1,8 @@
 using FluentValidation;
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 
-namespace DocumentOperator.Application;
+namespace DocumentService.Application;
 
 /// <summary>
 /// Dependency Injection configuration for Application Layer
@@ -11,13 +12,18 @@ public static class DependencyInjection
     /// <summary>
     /// Registers Application Layer services (MediatR, FluentValidation, AutoMapper, Behaviors)
     /// </summary>
-    public static IServiceCollection AddApplication(this IServiceCollection services)
+    public static IServiceCollection AddApplication(this IServiceCollection services, IConfiguration configuration)
     {
         var assembly = typeof(DependencyInjection).Assembly;
 
+        // Read LuckyPennySoft license key from appsettings.json
+        var licenseKey = configuration.GetValue<string>("LuckyPennySoftLicenseKey")
+            ?? throw new InvalidOperationException("LuckyPennySoftLicenseKey not found in configuration");
+
         // Register MediatR (scannt Assembly nach Handlers)
         services.AddMediatR(config =>
         {
+            config.LicenseKey = licenseKey;
             config.RegisterServicesFromAssembly(assembly);
 
             // Pipeline Behaviors (Reihenfolge wichtig!)
@@ -29,7 +35,9 @@ public static class DependencyInjection
         services.AddValidatorsFromAssembly(assembly);
 
         // Register AutoMapper (scannt Assembly nach Profiles)
-        services.AddAutoMapper(cfg => { }, typeof(Common.Mapping.MappingProfile));
+        services.AddAutoMapper(cfg => {
+            cfg.LicenseKey = licenseKey;
+        }, typeof(Common.Mapping.MappingProfile));
 
         return services;
     }

DocumentOperator.Application/DocumentService.Application.csproj

@@ -7,23 +7,30 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="AutoMapper" Version="16.2.0" />
-    <PackageReference Include="FluentValidation" Version="12.1.1" />
-    <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="12.1.1" />
-    <PackageReference Include="MediatR" Version="14.1.0" />
+    <Compile Remove="DependencyInjection\**" />
+    <Compile Remove="Features\**" />
+    <EmbeddedResource Remove="DependencyInjection\**" />
+    <EmbeddedResource Remove="Features\**" />
+    <None Remove="DependencyInjection\**" />
+    <None Remove="Features\**" />
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\DocumentOperator.Domain\DocumentOperator.Domain.csproj" />
+    <PackageReference Include="AutoMapper" Version="16.2.0" />
+    <PackageReference Include="Codecrete.SwissQRBill.Generator" Version="3.4.0" />
+    <PackageReference Include="FluentValidation" Version="12.1.1" />
+    <PackageReference Include="FluentValidation.DependencyInjectionExtensions" Version="12.1.1" />
+    <PackageReference Include="MediatR" Version="14.1.0" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Abstractions" Version="10.0.10" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="10.0.10" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\DocumentOperator.Domain\DocumentService.Domain.csproj" />
   </ItemGroup>
 
   <ItemGroup>
     <Folder Include="Common\Mappings\" />
-    <Folder Include="DependencyInjection\" />
-    <Folder Include="Features\Documents\ExtractAttachments\" />
-    <Folder Include="Features\Documents\ConcatenatePdfs\" />
-    <Folder Include="Features\Documents\ApplyStamp\" />
-    <Folder Include="Features\Documents\EmbedCertificate\" />
   </ItemGroup>
 
 </Project>

DocumentOperator.Application/ExtractPdfAttachments/ExtractPdfAttachmentsCommand.cs

@@ -0,0 +1,43 @@
+using DocumentService.Application.Common.Interfaces;
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.ExtractPdfAttachments;
+
+/// <summary>
+/// Command to extract all embedded files from a PDF document and return as ZIP archive.
+/// </summary>
+public record ExtractPdfAttachmentsCommand : IRequest<byte[]>
+{
+    /// <summary>
+    /// PDF document stream. Must be positioned at the beginning (Position = 0).
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for ExtractPdfAttachmentsCommand.
+/// Extracts all embedded files from PDF and returns as ZIP archive.
+/// </summary>
+public class ExtractPdfAttachmentsCommandHandler(IPdfProcessor pdfProcessor) 
+    : IRequestHandler<ExtractPdfAttachmentsCommand, byte[]>
+{
+    public async Task<byte[]> Handle(ExtractPdfAttachmentsCommand request, CancellationToken cancellationToken)
+    {
+        // Delegate to infrastructure layer
+        return await pdfProcessor.ExtractAttachmentsAsync(request.PdfStream);
+    }
+}
+
+/// <summary>
+/// Validator for ExtractPdfAttachmentsCommand.
+/// </summary>
+public class ExtractPdfAttachmentsCommandValidator : AbstractValidator<ExtractPdfAttachmentsCommand>
+{
+    public ExtractPdfAttachmentsCommandValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+    }
+}

DocumentOperator.Application/ExtractZugferd/ExtractZugferdCommand.cs

@@ -0,0 +1,113 @@
+using DocumentService.Application.Common.Configuration;
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Domain.Common.Exceptions;
+using FluentValidation;
+using MediatR;
+using Microsoft.Extensions.Options;
+
+namespace DocumentService.Application.ExtractZugferd;
+
+/// <summary>
+/// Command to extract ZUGFeRD XML from a PDF document
+/// </summary>
+public record ExtractZugferdCommand : IRequest<ZugferdExtractionResult>
+{
+    /// <summary>
+    /// PDF document stream. Must be positioned at the beginning (Position = 0).
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for ExtractZugferdCommand.
+/// Extracts ZUGFeRD XML from PDF and returns XML content
+/// </summary>
+public class ExtractZugferdCommandHandler(
+    IPdfProcessor pdfProcessor,
+    IOptions<ZugferdSettings> settings) 
+    : IRequestHandler<ExtractZugferdCommand, ZugferdExtractionResult>
+{
+    private readonly ZugferdSettings _settings = settings.Value;
+
+    public async Task<ZugferdExtractionResult> Handle(ExtractZugferdCommand request, CancellationToken cancellationToken)
+    {
+        // Get all attachments
+        var attachmentInfo = await pdfProcessor.CheckAttachmentsAsync(request.PdfStream);
+
+        // Find ZUGFeRD XML file using configured names and patterns
+        var zugferdAttachment = attachmentInfo.Attachments.FirstOrDefault(a =>
+            _settings.ZugferdFileNames.Any(name => 
+                a.FileName.Equals(name, StringComparison.OrdinalIgnoreCase)) ||
+            _settings.ZugferdFileNamePatterns.Any(pattern => 
+                a.FileName.Contains(pattern, StringComparison.OrdinalIgnoreCase)));
+
+        if (zugferdAttachment == null)
+        {
+            throw new NotFoundException("ZUGFeRD XML not found in PDF attachments");
+        }
+
+        // Reset stream position for extraction
+        request.PdfStream.Position = 0;
+
+        // Extract all attachments as ZIP
+        byte[] zipBytes = await pdfProcessor.ExtractAttachmentsAsync(request.PdfStream);
+
+        // Find ZUGFeRD XML in ZIP
+        using var zipStream = new MemoryStream(zipBytes);
+        using var zipArchive = new System.IO.Compression.ZipArchive(zipStream, System.IO.Compression.ZipArchiveMode.Read);
+
+        var zugferdEntry = zipArchive.Entries.FirstOrDefault(e =>
+            e.Name.Equals(zugferdAttachment.FileName, StringComparison.OrdinalIgnoreCase));
+
+        if (zugferdEntry == null)
+        {
+            throw new NotFoundException($"ZUGFeRD XML '{zugferdAttachment.FileName}' not found in extracted attachments");
+        }
+
+        // Read XML content
+        using var entryStream = zugferdEntry.Open();
+        using var reader = new StreamReader(entryStream);
+        string xmlContent = await reader.ReadToEndAsync(cancellationToken);
+
+        return new ZugferdExtractionResult
+        {
+            FileName = zugferdAttachment.FileName,
+            XmlContent = xmlContent,
+            FileSize = zugferdAttachment.SizeBytes
+        };
+    }
+}
+
+/// <summary>
+/// Validator for ExtractZugferdCommand.
+/// </summary>
+public class ExtractZugferdCommandValidator : AbstractValidator<ExtractZugferdCommand>
+{
+    public ExtractZugferdCommandValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+    }
+}
+
+/// <summary>
+/// Result DTO for ZUGFeRD extraction
+/// </summary>
+public record ZugferdExtractionResult
+{
+    /// <summary>
+    /// ZUGFeRD XML file name
+    /// </summary>
+    public required string FileName { get; init; }
+
+    /// <summary>
+    /// ZUGFeRD XML content as string
+    /// </summary>
+    public required string XmlContent { get; init; }
+
+    /// <summary>
+    /// File size in bytes
+    /// </summary>
+    public long FileSize { get; init; }
+}

DocumentOperator.Application/HasZugferd/Queries/HasZugferdQuery.cs

@@ -0,0 +1,62 @@
+using DocumentService.Application.Common.Configuration;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using MediatR;
+using Microsoft.Extensions.Options;
+
+namespace DocumentService.Application.HasZugferd.Queries;
+
+/// <summary>
+/// Query for checking if PDF contains ZUGFeRD XML attachment
+/// </summary>
+public record HasZugferdQuery : IRequest<ZugferdCheckResult>
+{
+    /// <summary>
+    /// PDF as stream (caller is responsible for disposal)
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for HasZugferdQuery
+/// Checks if PDF contains ZUGFeRD/Factur-X XML attachment
+/// </summary>
+public class HasZugferdQueryHandler(
+    IPdfProcessor pdfProcessor,
+    IOptions<ZugferdSettings> settings)
+    : IRequestHandler<HasZugferdQuery, ZugferdCheckResult>
+{
+    private readonly ZugferdSettings _settings = settings.Value;
+
+    /// <summary>
+    /// Checks if PDF contains ZUGFeRD XML and returns metadata
+    /// </summary>
+    public async Task<ZugferdCheckResult> Handle(HasZugferdQuery request, CancellationToken cancellationToken)
+    {
+        // Get all attachments
+        var attachmentInfo = await pdfProcessor.CheckAttachmentsAsync(request.PdfStream);
+
+        // Check for ZUGFeRD/Factur-X XML files using configured names and patterns
+        var zugferdAttachment = attachmentInfo.Attachments.FirstOrDefault(a =>
+            _settings.ZugferdFileNames.Any(name => 
+                a.FileName.Equals(name, StringComparison.OrdinalIgnoreCase)) ||
+            _settings.ZugferdFileNamePatterns.Any(pattern => 
+                a.FileName.Contains(pattern, StringComparison.OrdinalIgnoreCase)));
+
+        if (zugferdAttachment != null)
+        {
+            return new ZugferdCheckResult
+            {
+                HasZugferd = true,
+                ZugferdFileName = zugferdAttachment.FileName,
+                ZugferdFileSize = zugferdAttachment.SizeBytes,
+                ZugferdMimeType = zugferdAttachment.MimeType
+            };
+        }
+
+        return new ZugferdCheckResult
+        {
+            HasZugferd = false
+        };
+    }
+}

DocumentOperator.Application/HasZugferd/Queries/HasZugferdQueryValidator.cs

@@ -0,0 +1,16 @@
+using FluentValidation;
+
+namespace DocumentService.Application.HasZugferd.Queries;
+
+/// <summary>
+/// Validator for HasZugferdQuery
+/// </summary>
+public class HasZugferdQueryValidator : AbstractValidator<HasZugferdQuery>
+{
+    public HasZugferdQueryValidator()
+    {
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PDF stream is required");
+    }
+}

DocumentOperator.Application/MergePdfs/MergePdfsCommand.cs

@@ -0,0 +1,53 @@
+using DocumentService.Application.Common.Interfaces;
+using FluentValidation;
+using MediatR;
+
+namespace DocumentService.Application.MergePdfs;
+
+/// <summary>
+/// Command to merge multiple PDF documents into a single PDF.
+/// </summary>
+public record MergePdfsCommand : IRequest<byte[]>
+{
+    /// <summary>
+    /// PDF streams to merge. Minimum 2 required. Each must be at Position=0.
+    /// </summary>
+    public required IReadOnlyList<Stream> PdfStreams { get; init; }
+
+    /// <summary>
+    /// Optional page ranges per PDF (null = all pages). 
+    /// Format: "1-3,5" means pages 1, 2, 3, and 5.
+    /// If provided, array length must match PdfStreams length.
+    /// </summary>
+    public IReadOnlyList<string?>? PageRanges { get; init; }
+}
+
+/// <summary>
+/// Handler for MergePdfsCommand.
+/// Delegates PDF merge operation to infrastructure layer.
+/// </summary>
+public class MergePdfsCommandHandler(IPdfProcessor pdfProcessor) 
+    : IRequestHandler<MergePdfsCommand, byte[]>
+{
+    public async Task<byte[]> Handle(MergePdfsCommand request, CancellationToken cancellationToken)
+    {
+        return await pdfProcessor.MergePdfsAsync(request.PdfStreams, request.PageRanges);
+    }
+}
+
+/// <summary>
+/// Validator for MergePdfsCommand.
+/// </summary>
+public class MergePdfsCommandValidator : AbstractValidator<MergePdfsCommand>
+{
+    public MergePdfsCommandValidator()
+    {
+        RuleFor(x => x.PdfStreams)
+            .NotNull()
+            .WithMessage("PDF streams are required");
+
+        RuleFor(x => x.PdfStreams)
+            .Must(streams => streams != null && streams.Count >= 2)
+            .WithMessage("At least 2 PDF files are required for merging");
+    }
+}

DocumentOperator.Application/SwissQrCode/Queries/ExtractSwissQrCodeQuery.cs

@@ -1,29 +1,19 @@
 using AutoMapper;
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.Common.Interfaces;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
 using MediatR;
 
-namespace DocumentOperator.Application.SwissQrCode.Queries;
+namespace DocumentService.Application.SwissQrCode.Queries;
 
 /// <summary>
-/// Query for extracting Swiss QR Code from PDF (supports both byte array and Base64 input)
+/// Query for extracting Swiss QR Code from PDF (Stream-based)
 /// </summary>
 public record ExtractSwissQrCodeQuery : IRequest<SwissQrCodeExtractionResult>
 {
     /// <summary>
-    /// PDF as byte array (direct upload)
+    /// PDF as stream (caller is responsible for disposal)
     /// </summary>
-    public byte[]? PdfBytes { get; init; }
-
-    /// <summary>
-    /// PDF as Base64 string (API clients)
-    /// </summary>
-    public string? Base64Pdf { get; init; }
-
-    /// <summary>
-    /// Optional reference strings (passed through to response for external tracking)
-    /// </summary>
-    public IReadOnlyList<string>? References { get; init; }
+    public required Stream PdfStream { get; init; }
 }
 
 /// <summary>
@@ -34,23 +24,21 @@ public class ExtractSwissQrCodeQueryHandler(ISwissQrCodeProcessor qrCodeProcesso
     : IRequestHandler<ExtractSwissQrCodeQuery, SwissQrCodeExtractionResult>
 {
     /// <summary>
-    /// Extracts and parses Swiss QR Code from the last page of the PDF
+    /// Extracts and parses Swiss QR Code from the PDF (default: scans all pages starting with last)
+    /// Returns both parsed Bill DTO and raw QR text lines
     /// </summary>
     public async Task<SwissQrCodeExtractionResult> Handle(ExtractSwissQrCodeQuery request, CancellationToken cancellationToken)
     {
-        // Use byte[] if available, otherwise convert Base64
-        byte[] pdfBytes = request.PdfBytes ?? Convert.FromBase64String(request.Base64Pdf!);
+        // Extract: returns (Bill, RawLines) - pass stream directly
+        var (bill, rawLines) = await qrCodeProcessor.ExtractSwissQrCodeAsync(request.PdfStream, pageNumbers: null, cancellationToken);
 
-        // Extract and parse Swiss QR Code from last page (can throw PdfProcessingException or QrCodeNotFoundException)
-        var qrCodeData = await qrCodeProcessor.ExtractSwissQrCodeAsync(pdfBytes, cancellationToken);
+        // Map Codecrete Bill to DTO using AutoMapper
+        var billDto = mapper.Map<SwissQrBillDto>(bill);
 
-        // Map domain value object to DTO using AutoMapper
-        var qrCodeDto = mapper.Map<SwissQrCodeDataDto>(qrCodeData);
-
-        // Return references (passed through) + QR code data
+        // Return references (passed through) + Bill DTO + raw lines
         return new SwissQrCodeExtractionResult(
-            References: request.References ?? [],
-            QrCodeData: qrCodeDto
+            Bill: billDto,
+            RawLines: rawLines
         );
     }
 }

DocumentOperator.Application/SwissQrCode/Queries/ExtractSwissQrCodeQueryValidator.cs

@@ -1,59 +1,19 @@
-using DocumentOperator.Application.SwissQrCode.Queries;
+using DocumentService.Application.SwissQrCode.Queries;
 using FluentValidation;
 
-namespace DocumentOperator.Application.SwissQrCode.Queries;
+namespace DocumentService.Application.SwissQrCode.Queries;
 
 /// <summary>
 /// Validates ExtractSwissQrCodeQuery before handler execution.
-/// Ensures exactly ONE input method is provided (either PdfBytes OR Base64Pdf, not both, not none).
+/// Ensures PdfStream is not null.
 /// </summary>
 public sealed class ExtractSwissQrCodeQueryValidator : AbstractValidator<ExtractSwissQrCodeQuery>
 {
     public ExtractSwissQrCodeQueryValidator()
     {
-        RuleFor(x => x)
-            .Must(HasExactlyOneInput)
-            .WithMessage("Either PdfBytes or Base64Pdf must be provided, but not both");
-
-        // Validate Base64 format if provided
-        When(x => !string.IsNullOrWhiteSpace(x.Base64Pdf), () =>
-        {
-            RuleFor(x => x.Base64Pdf)
-                .Must(BeValidBase64)
-                .WithMessage("Invalid Base64 format");
-        });
-
-        // Validate byte array if provided
-        When(x => x.PdfBytes != null, () =>
-        {
-            RuleFor(x => x.PdfBytes)
-                .NotEmpty()
-                .WithMessage("PdfBytes cannot be empty");
-        });
-    }
-
-    private static bool HasExactlyOneInput(ExtractSwissQrCodeQuery request)
-    {
-        var hasPdfBytes = request.PdfBytes != null && request.PdfBytes.Length > 0;
-        var hasBase64 = !string.IsNullOrWhiteSpace(request.Base64Pdf);
-
-        // XOR: exactly one must be true
-        return hasPdfBytes ^ hasBase64;
-    }
-
-    private static bool BeValidBase64(string? base64)
-    {
-        if (string.IsNullOrWhiteSpace(base64))
-            return false;
-
-        try
-        {
-            Convert.FromBase64String(base64);
-            return true;
-        }
-        catch (FormatException)
-        {
-            return false;
-        }
+        // Rule: PdfStream must be provided
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PdfStream is required");
     }
 }

DocumentOperator.Application/ValidatePdf/Queries/ValidatePdfQuery.cs

@@ -1,24 +1,19 @@
 using AutoMapper;
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.Common.Interfaces;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
 using MediatR;
 
-namespace DocumentOperator.Application.ValidatePdf.Queries;
+namespace DocumentService.Application.ValidatePdf.Queries;
 
 /// <summary>
-/// Query for PDF validation (supports both byte array and Base64 input)
+/// Query for PDF validation (Stream-based)
 /// </summary>
 public record ValidatePdfQuery : IRequest<PdfValidationResult>
 {
     /// <summary>
-    /// PDF as byte array (direct upload)
+    /// PDF as stream (caller is responsible for disposal)
     /// </summary>
-    public byte[]? PdfBytes { get; init; }
-
-    /// <summary>
-    /// PDF as Base64 string (API clients)
-    /// </summary>
-    public string? Base64Pdf { get; init; }
+    public required Stream PdfStream { get; init; }
 }
 
 /// <summary>
@@ -33,13 +28,10 @@ public class ValidatePdfQueryHandler(IPdfProcessor PdfProcessor, IMapper Mapper)
     /// </summary>
     public async Task<PdfValidationResult> Handle(ValidatePdfQuery request, CancellationToken cancellationToken)
     {
-        // Use byte[] if available, otherwise convert Base64
-        byte[] pdfBytes = request.PdfBytes ?? Convert.FromBase64String(request.Base64Pdf!);
+        // Call DevExpress service directly with stream (exceptions propagate naturally)
+        var metadata = await PdfProcessor.ValidateAsync(request.PdfStream);
 
-        // Call DevExpress service (can throw PdfProcessingException)
-        var metadata = await PdfProcessor.ValidateAsync(pdfBytes);
-
-        // Map domain entity to DTO using AutoMapper
+        // Map DTO to response DTO using AutoMapper
         return Mapper.Map<PdfValidationResult>(metadata);
     }
 }

DocumentOperator.Application/ValidatePdf/Queries/ValidatePdfQueryValidator.cs

@@ -1,59 +1,19 @@
-using DocumentOperator.Application.ValidatePdf.Queries;
+using DocumentService.Application.ValidatePdf.Queries;
 using FluentValidation;
 
-namespace DocumentOperator.Application.ValidatePdf.Queries;
+namespace DocumentService.Application.ValidatePdf.Queries;
 
 /// <summary>
 /// Validator for ValidatePdfQuery
-/// Ensures exactly ONE input method is provided (either PdfBytes OR Base64Pdf, not both, not none)
+/// Ensures PdfStream is not null
 /// </summary>
 public class ValidatePdfQueryValidator : AbstractValidator<ValidatePdfQuery>
 {
     public ValidatePdfQueryValidator()
     {
-        RuleFor(x => x)
-            .Must(HasExactlyOneInput)
-            .WithMessage("Either PdfBytes or Base64Pdf must be provided, but not both");
-
-        // Validate Base64 format if provided
-        When(x => !string.IsNullOrWhiteSpace(x.Base64Pdf), () =>
-        {
-            RuleFor(x => x.Base64Pdf)
-                .Must(BeValidBase64)
-                .WithMessage("Invalid Base64 format");
-        });
-
-        // Validate byte array if provided
-        When(x => x.PdfBytes != null, () =>
-        {
-            RuleFor(x => x.PdfBytes)
-                .NotEmpty()
-                .WithMessage("PdfBytes cannot be empty");
-        });
-    }
-
-    private static bool HasExactlyOneInput(ValidatePdfQuery request)
-    {
-        var hasPdfBytes = request.PdfBytes != null && request.PdfBytes.Length > 0;
-        var hasBase64 = !string.IsNullOrWhiteSpace(request.Base64Pdf);
-
-        // XOR: exactly one must be true
-        return hasPdfBytes ^ hasBase64;
-    }
-
-    private static bool BeValidBase64(string? base64)
-    {
-        if (string.IsNullOrWhiteSpace(base64))
-            return false;
-
-        try
-        {
-            Convert.FromBase64String(base64);
-            return true;
-        }
-        catch (FormatException)
-        {
-            return false;
-        }
+        // Rule: PdfStream must be provided
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PdfStream is required");
     }
 }

DocumentOperator.Application/ValidatePdfA/Queries/ValidatePdfAQuery.cs

@@ -0,0 +1,37 @@
+using AutoMapper;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using MediatR;
+
+namespace DocumentService.Application.ValidatePdfA.Queries;
+
+/// <summary>
+/// Query for PDF/A validation (Stream-based)
+/// </summary>
+public record ValidatePdfAQuery : IRequest<PdfAValidationResult>
+{
+    /// <summary>
+    /// PDF as stream (caller is responsible for disposal)
+    /// </summary>
+    public required Stream PdfStream { get; init; }
+}
+
+/// <summary>
+/// Handler for ValidatePdfAQuery
+/// Orchestrates PDF/A validation using IPdfProcessor and AutoMapper
+/// </summary>
+public class ValidatePdfAQueryHandler(IPdfProcessor PdfProcessor, IMapper Mapper) 
+    : IRequestHandler<ValidatePdfAQuery, PdfAValidationResult>
+{
+    /// <summary>
+    /// Validates PDF/A and returns metadata with conformance level
+    /// </summary>
+    public async Task<PdfAValidationResult> Handle(ValidatePdfAQuery request, CancellationToken cancellationToken)
+    {
+        // Call DevExpress service directly with stream (exceptions propagate naturally)
+        var metadata = await PdfProcessor.ValidatePdfAAsync(request.PdfStream);
+
+        // Map DTO to response DTO using AutoMapper
+        return Mapper.Map<PdfAValidationResult>(metadata);
+    }
+}

DocumentOperator.Application/ValidatePdfA/Validators/ValidatePdfAQueryValidator.cs

@@ -0,0 +1,18 @@
+using FluentValidation;
+
+namespace DocumentService.Application.ValidatePdfA.Validators;
+
+/// <summary>
+/// Validator for ValidatePdfAQuery
+/// Ensures PdfStream is not null
+/// </summary>
+public class ValidatePdfAQueryValidator : AbstractValidator<Queries.ValidatePdfAQuery>
+{
+    public ValidatePdfAQueryValidator()
+    {
+        // Rule: PdfStream must be provided
+        RuleFor(x => x.PdfStream)
+            .NotNull()
+            .WithMessage("PdfStream is required");
+    }
+}

DocumentOperator.Domain/Common/Exceptions/BadRequestException.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.Serialization;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace DocumentService.Domain.Common.Exceptions;
+
+public class BadRequestException : Exception
+{
+    public BadRequestException()
+    {
+    }
+
+    public BadRequestException(string? message) : base(message)
+    {
+    }
+
+    public BadRequestException(string? message, Exception? innerException) : base(message, innerException)
+    {
+    }
+}

DocumentOperator.Domain/Common/Exceptions/DomainException.cs

@@ -1,9 +1,10 @@
-namespace DocumentOperator.Domain.Common.Exceptions;
+namespace DocumentService.Domain.Common.Exceptions;
 
 /// <summary>
 /// Base exception for all domain-related exceptions.
 /// Caught by the Exception Handling Middleware in the API layer.
 /// </summary>
+[Obsolete("This exception is deprecated. Use more specific exceptions for domain errors.")]
 public abstract class DomainException : Exception
 {
     /// <summary>

DocumentOperator.Domain/Common/Exceptions/DomainValidationException.cs

@@ -1,9 +1,10 @@
-namespace DocumentOperator.Domain.Common.Exceptions;
+namespace DocumentService.Domain.Common.Exceptions;
 
 /// <summary>
 /// Exception thrown when domain validation fails (e.g., invalid Value Objects).
 /// Maps to HTTP 400 Bad Request in the API layer.
 /// </summary>
+[Obsolete("This exception is deprecated. Use more specific exceptions for domain validation errors.")]
 public class DomainValidationException : DomainException
 {
     public string PropertyName { get; }

DocumentOperator.Domain/Common/Exceptions/NotFoundException.cs

@@ -1,25 +1,22 @@
-namespace DocumentOperator.Domain.Common.Exceptions;
+using System.Runtime.Serialization;
+
+namespace DocumentService.Domain.Common.Exceptions;
 
 /// <summary>
 /// Exception thrown when a requested resource is not found.
 /// Maps to HTTP 404 Not Found in the API layer.
 /// </summary>
-public class NotFoundException : DomainException
+public class NotFoundException : Exception
 {
-    public string ResourceType { get; }
-    public object ResourceId { get; }
-
-    public NotFoundException(string resourceType, object resourceId)
-        : base($"{resourceType} with ID '{resourceId}' was not found.", "RESOURCE_NOT_FOUND")
+    public NotFoundException()
     {
-        ResourceType = resourceType;
-        ResourceId = resourceId;
     }
 
-    public NotFoundException(string resourceType, object resourceId, string customMessage)
-        : base(customMessage, "RESOURCE_NOT_FOUND")
+    public NotFoundException(string? message) : base(message)
+    {
+    }
+
+    public NotFoundException(string? message, Exception? innerException) : base(message, innerException)
     {
-        ResourceType = resourceType;
-        ResourceId = resourceId;
     }
 }

DocumentOperator.Domain/Common/Exceptions/PdfProcessingException.cs

@@ -1,34 +0,0 @@
-namespace DocumentOperator.Domain.Common.Exceptions;
-
-/// <summary>
-/// Exception thrown when PDF processing operations fail.
-/// Maps to HTTP 500 Internal Server Error or 422 Unprocessable Entity in the API layer.
-/// </summary>
-public class PdfProcessingException : DomainException
-{
-    public string Operation { get; }
-
-    public PdfProcessingException(string operation, string message)
-        : base($"PDF processing failed during '{operation}': {message}", "PDF_PROCESSING_ERROR")
-    {
-        Operation = operation;
-    }
-
-    public PdfProcessingException(string operation, string message, Exception innerException)
-        : base($"PDF processing failed during '{operation}': {message}", "PDF_PROCESSING_ERROR", innerException)
-    {
-        Operation = operation;
-    }
-
-    public PdfProcessingException(string message)
-        : base(message, "PDF_PROCESSING_ERROR")
-    {
-        Operation = "Unknown";
-    }
-
-    public PdfProcessingException(string message, Exception innerException)
-        : base(message, "PDF_PROCESSING_ERROR", innerException)
-    {
-        Operation = "Unknown";
-    }
-}

DocumentOperator.Domain/DocumentOperator.Domain.csproj

@@ -1,14 +0,0 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
-  <PropertyGroup>
-    <TargetFramework>net8.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-  </PropertyGroup>
-
-  <ItemGroup>
-    <Folder Include="Common\Results\" />
-    <Folder Include="Constants\" />
-  </ItemGroup>
-
-</Project>

DocumentOperator.Domain/DocumentService.Domain.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <Compile Remove="Common\Results\**" />
+    <Compile Remove="Constants\**" />
+    <EmbeddedResource Remove="Common\Results\**" />
+    <EmbeddedResource Remove="Constants\**" />
+    <None Remove="Common\Results\**" />
+    <None Remove="Constants\**" />
+  </ItemGroup>
+
+</Project>

DocumentOperator.Domain/Exceptions/SwissQrCodeNotFoundException.cs

@@ -1,22 +0,0 @@
-namespace DocumentOperator.Domain.Exceptions;
-
-/// <summary>
-/// Exception thrown when a Swiss QR Code cannot be found in a PDF document.
-/// </summary>
-public sealed class SwissQrCodeNotFoundException : Exception
-{
-    public SwissQrCodeNotFoundException()
-        : base("No Swiss QR Code found on the last page of the PDF document.")
-    {
-    }
-
-    public SwissQrCodeNotFoundException(string message)
-        : base(message)
-    {
-    }
-
-    public SwissQrCodeNotFoundException(string message, Exception innerException)
-        : base(message, innerException)
-    {
-    }
-}

DocumentOperator.Domain/Models/Enums/DocumentOperationType.cs

@@ -1,10 +0,0 @@
-namespace DocumentOperator.Domain.Models.Enums;
-
-public enum DocumentOperationType
-{
-    Validate,
-    ExtractAttachments,
-    Concatenate,
-    ApplyStamp,
-    EmbedCertificate
-}

DocumentOperator.Domain/Models/Enums/ProcessingStatus.cs

@@ -1,9 +0,0 @@
-namespace DocumentOperator.Domain.Models.Enums;
-
-public enum ProcessingStatus
-{
-    Pending,
-    Processing,
-    Success,
-    Failed
-}

DocumentOperator.Domain/Models/ValueObjects/AnnotationOrigin.cs

@@ -0,0 +1,18 @@
+namespace DocumentService.Domain.Models.ValueObjects;
+
+/// <summary>
+/// Coordinate origin point for PDF annotations.
+/// PDF default is BottomLeft, but users may prefer TopLeft for easier UI integration.
+/// </summary>
+public enum AnnotationOrigin
+{
+    /// <summary>
+    /// Bottom-left corner (PDF native coordinate system, default)
+    /// </summary>
+    BottomLeft,
+    
+    /// <summary>
+    /// Top-left corner (common in UI frameworks)
+    /// </summary>
+    TopLeft
+}

DocumentOperator.Domain/Models/ValueObjects/AnnotationType.cs

@@ -0,0 +1,32 @@
+namespace DocumentService.Domain.Models.ValueObjects;
+
+/// <summary>
+/// Supported PDF annotation types
+/// </summary>
+public enum AnnotationType
+{
+    /// <summary>
+    /// Text markup annotation (highlight, underline, strikeout)
+    /// </summary>
+    TextMarkup,
+    
+    /// <summary>
+    /// Free text annotation (text box with visible text)
+    /// </summary>
+    FreeText,
+    
+    /// <summary>
+    /// Sticky note annotation (popup comment icon)
+    /// </summary>
+    StickyNote,
+    
+    /// <summary>
+    /// Circle shape annotation
+    /// </summary>
+    Circle,
+    
+    /// <summary>
+    /// Square shape annotation
+    /// </summary>
+    Square
+}

DocumentOperator.Domain/Models/ValueObjects/PdfMetadata.cs

@@ -1,32 +0,0 @@
-namespace DocumentOperator.Domain.Models.ValueObjects;
-
-public sealed class PdfMetadata
-{
-    public int PageCount { get; }
-    public long FileSizeBytes { get; }
-    public string PdfVersion { get; }
-    public bool HasAttachments { get; }
-    public int AttachmentCount { get; }
-
-    // Computed Property (berechnet aus FileSizeBytes)
-    public double FileSizeMB => FileSizeBytes / 1024.0 / 1024.0;
-
-    public PdfMetadata(
-        int pageCount,
-        long fileSizeBytes,
-        string pdfVersion,
-        bool hasAttachments,
-        int attachmentCount)
-    {
-        PageCount = pageCount;
-        FileSizeBytes = fileSizeBytes;
-        PdfVersion = pdfVersion;
-        HasAttachments = hasAttachments;
-        AttachmentCount = attachmentCount;
-    }
-
-    public override string ToString()
-    {
-        return $"PDF: {PageCount} pages, {FileSizeMB:F2} MB, Version {PdfVersion}, Attachments: {AttachmentCount}";
-    }
-}

DocumentOperator.Domain/Models/ValueObjects/PredefinedStampType.cs

@@ -0,0 +1,32 @@
+namespace DocumentService.Domain.Models.ValueObjects;
+
+/// <summary>
+/// Predefined stamp types with standard text and styling.
+/// </summary>
+public enum PredefinedStampType
+{
+    /// <summary>
+    /// CONFIDENTIAL stamp (red, bold).
+    /// </summary>
+    Confidential,
+
+    /// <summary>
+    /// APPROVED stamp (green, bold).
+    /// </summary>
+    Approved,
+
+    /// <summary>
+    /// DRAFT stamp (gray, italic).
+    /// </summary>
+    Draft,
+
+    /// <summary>
+    /// VOID stamp (red, strikethrough effect).
+    /// </summary>
+    Void,
+
+    /// <summary>
+    /// FOR REVIEW stamp (orange, bold).
+    /// </summary>
+    ForReview
+}

DocumentOperator.Domain/Models/ValueObjects/StampPlacement.cs

@@ -0,0 +1,17 @@
+namespace DocumentService.Domain.Models.ValueObjects;
+
+/// <summary>
+/// Specifies whether the stamp should appear in the foreground (on top of content) or background (behind content).
+/// </summary>
+public enum StampPlacement
+{
+    /// <summary>
+    /// Stamp appears on top of existing page content.
+    /// </summary>
+    Foreground,
+
+    /// <summary>
+    /// Stamp appears behind existing page content (watermark effect).
+    /// </summary>
+    Background
+}

DocumentOperator.Domain/Models/ValueObjects/StampType.cs

@@ -0,0 +1,22 @@
+namespace DocumentService.Domain.Models.ValueObjects;
+
+/// <summary>
+/// Specifies the type of stamp to add to a PDF document.
+/// </summary>
+public enum StampType
+{
+    /// <summary>
+    /// Text-based stamp with custom text, font, and color.
+    /// </summary>
+    Text,
+
+    /// <summary>
+    /// Image-based stamp (PNG/JPEG overlay).
+    /// </summary>
+    Image,
+
+    /// <summary>
+    /// Predefined stamp with standard text (e.g., CONFIDENTIAL, APPROVED).
+    /// </summary>
+    Predefined
+}

DocumentOperator.Domain/Models/ValueObjects/TenantId.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.Domain.Models.ValueObjects;
+namespace DocumentService.Domain.Models.ValueObjects;
 
 public sealed class TenantId
 {

DocumentOperator.Domain/Models/ValueObjects/TextMarkupStyle.cs

@@ -0,0 +1,23 @@
+namespace DocumentService.Domain.Models.ValueObjects;
+
+/// <summary>
+/// Text markup annotation style (highlight, underline, strikeout)
+/// Maps to DevExpress PdfTextMarkupAnnotationType
+/// </summary>
+public enum TextMarkupStyle
+{
+    /// <summary>
+    /// Highlight text with background color
+    /// </summary>
+    Highlight,
+    
+    /// <summary>
+    /// Underline text
+    /// </summary>
+    Underline,
+    
+    /// <summary>
+    /// Strikeout text (strikethrough)
+    /// </summary>
+    Strikeout
+}

DocumentOperator.Domain/ValueObjects/SwissQrCodeData.cs

@@ -1,129 +0,0 @@
-namespace DocumentOperator.Domain.ValueObjects;
-
-/// <summary>
-/// Represents Swiss QR Code data according to Swiss QR Bill Standard 2.0.
-/// Immutable value object containing all fields from a Swiss QR payment part.
-/// </summary>
-public sealed record SwissQrCodeData
-{
-    /// <summary>
-    /// QR type - always "SPC" for Swiss Payment Code
-    /// </summary>
-    public required string QrType { get; init; }
-
-    /// <summary>
-    /// Version of the Swiss QR Code standard (e.g., "0200" for version 2.0)
-    /// </summary>
-    public required string Version { get; init; }
-
-    /// <summary>
-    /// Character set code (always "1" for UTF-8)
-    /// </summary>
-    public required string CodingType { get; init; }
-
-    /// <summary>
-    /// IBAN of the creditor (payee)
-    /// </summary>
-    public required string Iban { get; init; }
-
-    /// <summary>
-    /// Creditor (payee) information
-    /// </summary>
-    public required AddressData Creditor { get; init; }
-
-    /// <summary>
-    /// Ultimate creditor information (optional)
-    /// </summary>
-    public AddressData? UltimateCreditor { get; init; }
-
-    /// <summary>
-    /// Payment amount (null if not specified)
-    /// </summary>
-    public decimal? Amount { get; init; }
-
-    /// <summary>
-    /// Currency code (CHF or EUR)
-    /// </summary>
-    public required string Currency { get; init; }
-
-    /// <summary>
-    /// Ultimate debtor (payer) information (optional)
-    /// </summary>
-    public AddressData? UltimateDebtor { get; init; }
-
-    /// <summary>
-    /// Reference type (QRR, SCOR, or NON)
-    /// </summary>
-    public required string ReferenceType { get; init; }
-
-    /// <summary>
-    /// Payment reference (format depends on ReferenceType)
-    /// </summary>
-    public string? Reference { get; init; }
-
-    /// <summary>
-    /// Unstructured message (max 140 characters)
-    /// </summary>
-    public string? UnstructuredMessage { get; init; }
-
-    /// <summary>
-    /// Bill information (structured data for automated processing)
-    /// </summary>
-    public string? BillInformation { get; init; }
-
-    /// <summary>
-    /// Alternative procedure parameters (up to 2 entries)
-    /// </summary>
-    public IReadOnlyList<string>? AlternativeProcedureParameters { get; init; }
-}
-
-/// <summary>
-/// Represents address data in Swiss QR Code (creditor or debtor)
-/// </summary>
-public sealed record AddressData
-{
-    /// <summary>
-    /// Address type: "S" for structured, "K" for combined
-    /// </summary>
-    public required string AddressType { get; init; }
-
-    /// <summary>
-    /// Name of person or company
-    /// </summary>
-    public required string Name { get; init; }
-
-    /// <summary>
-    /// Street name (structured address only)
-    /// </summary>
-    public string? Street { get; init; }
-
-    /// <summary>
-    /// Building number (structured address only)
-    /// </summary>
-    public string? BuildingNumber { get; init; }
-
-    /// <summary>
-    /// Address line 1 (combined address only)
-    /// </summary>
-    public string? AddressLine1 { get; init; }
-
-    /// <summary>
-    /// Address line 2 (combined address only)
-    /// </summary>
-    public string? AddressLine2 { get; init; }
-
-    /// <summary>
-    /// Postal code
-    /// </summary>
-    public required string PostalCode { get; init; }
-
-    /// <summary>
-    /// City/town name
-    /// </summary>
-    public required string City { get; init; }
-
-    /// <summary>
-    /// Two-letter country code (ISO 3166-1 alpha-2)
-    /// </summary>
-    public required string Country { get; init; }
-}

DocumentOperator.Infrastructure/Configuration/ApiKeySettings.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.Infrastructure.Configuration;
+namespace DocumentService.Infrastructure.Configuration;
 
 public class ApiKeySettings
 {

DocumentOperator.Infrastructure/Configuration/DocumentServiceSettings.cs

@@ -1,8 +1,8 @@
-namespace DocumentOperator.Infrastructure.Configuration;
+namespace DocumentService.Infrastructure.Configuration;
 
-public class DocumentOperatorSettings
+public class DocumentServiceSettings
 {
-    public const string SectionName = "DocumentOperatorSettings";
+    public const string SectionName = "DocumentServiceSettings";
 
     public string TempFolderPath { get; set; } = string.Empty;
     public int TempFileRetentionHours { get; set; }

DocumentOperator.Infrastructure/Configuration/RedisSettings.cs

@@ -1,10 +1,10 @@
-namespace DocumentOperator.Infrastructure.Configuration;
+namespace DocumentService.Infrastructure.Configuration;
 
 public class RedisSettings
 {
     public const string SectionName = "RedisSettings";
 
     public string ConnectionString { get; set; } = "localhost:6379";
-    public string InstanceName { get; set; } = "DocumentOperator:";
+    public string InstanceName { get; set; } = "DocumentService:";
     public int CacheExpirationMinutes { get; set; } = 60;
 }

DocumentOperator.Infrastructure/Configuration/TenantInfo.cs

@@ -1,4 +1,4 @@
-namespace DocumentOperator.Infrastructure.Configuration;
+namespace DocumentService.Infrastructure.Configuration;
 
 public class TenantInfo
 {

DocumentOperator.Infrastructure/DependencyInjection.cs

@@ -1,9 +1,9 @@
-using DocumentOperator.Application.Common.Interfaces;
-using DocumentOperator.Infrastructure.Services.PdfProcessing;
-using DocumentOperator.Infrastructure.Services.QrCodeProcessing;
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Infrastructure.Services.PdfProcessing;
+using DocumentService.Infrastructure.Services.QrCodeProcessing;
 using Microsoft.Extensions.DependencyInjection;
 
-namespace DocumentOperator.Infrastructure;
+namespace DocumentService.Infrastructure;
 
 /// <summary>
 /// Dependency Injection configuration for Infrastructure Layer

DocumentOperator.Infrastructure/DocumentService.Infrastructure.csproj

@@ -6,23 +6,29 @@
     <Nullable>enable</Nullable>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Compile Remove="DependencyInjection\**" />
+    <Compile Remove="Services\DocumentValidation\**" />
+    <Compile Remove="Services\FileStorage\**" />
+    <EmbeddedResource Remove="DependencyInjection\**" />
+    <EmbeddedResource Remove="Services\DocumentValidation\**" />
+    <EmbeddedResource Remove="Services\FileStorage\**" />
+    <None Remove="DependencyInjection\**" />
+    <None Remove="Services\DocumentValidation\**" />
+    <None Remove="Services\FileStorage\**" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Codecrete.SwissQRBill.Generator" Version="3.4.0" />
     <PackageReference Include="DevExpress.Document.Processor" Version="26.1.3" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="8.0.0" />
+    <PackageReference Include="SkiaSharp.QrCode" Version="1.0.0" />
     <PackageReference Include="System.Drawing.Common" Version="10.0.9" />
-    <PackageReference Include="ZXing.Net.Bindings.Windows.Compatibility" Version="0.16.14" />
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\DocumentOperator.Application\DocumentOperator.Application.csproj" />
-    <ProjectReference Include="..\DocumentOperator.Domain\DocumentOperator.Domain.csproj" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <Folder Include="DependencyInjection\" />
-    <Folder Include="Services\FileStorage\" />
-    <Folder Include="Services\DocumentValidation\" />
+    <ProjectReference Include="..\DocumentOperator.Application\DocumentService.Application.csproj" />
+    <ProjectReference Include="..\DocumentOperator.Domain\DocumentService.Domain.csproj" />
   </ItemGroup>
 
 </Project>

DocumentOperator.Infrastructure/Services/QrCodeProcessing/DevExpressSwissQrCodeProcessor.cs

@@ -1,195 +1,165 @@
 using Codecrete.SwissQRBill.Generator;
 using DevExpress.Drawing;
 using DevExpress.Pdf;
-using DocumentOperator.Application.Common.Interfaces;
-using DocumentOperator.Domain.Exceptions;
-using DocumentOperator.Domain.ValueObjects;
-using System.Drawing;
-using System.Runtime.Versioning;
-using ZXing;
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Domain.Common.Exceptions;
+using SkiaSharp;
+using SkiaSharp.QrCode;
+using System.Collections.Concurrent;
 
-namespace DocumentOperator.Infrastructure.Services.QrCodeProcessing;
+namespace DocumentService.Infrastructure.Services.QrCodeProcessing;
 
 /// <summary>
-/// Swiss QR Code processor using DevExpress PDF API for PDF access
-/// and Codecrete.SwissQRBill.Generator for QR Code parsing.
+/// Swiss QR Code processor using DevExpress PDF API for image extraction,
+/// SkiaSharp.QrCode for QR decoding, and Codecrete.SwissQRBill.Generator for Swiss QR parsing.
+/// 
+/// Strategy:
+/// 1. Extract all embedded images from PDF using GetDXImages()
+/// 2. Try to decode QR code from each image using SkiaSharp.QrCode
+/// 3. Parse Swiss QR format with Codecrete library
+/// 4. Return both parsed Bill and raw QR text lines
 /// </summary>
 public sealed class DevExpressSwissQrCodeProcessor : ISwissQrCodeProcessor
 {
-    private const int QrCodeSearchDpi = 300; // High DPI for better QR code recognition
 
     /// <inheritdoc />
-    [SupportedOSPlatform("windows")]
-    public async Task<SwissQrCodeData> ExtractSwissQrCodeAsync(byte[] pdfBytes, CancellationToken cancellationToken = default)
+    public async Task<(Bill Bill, string[] RawLines)> ExtractSwissQrCodeAsync(
+        Stream pdfStream,
+        int[]? pageNumbers = null,
+        CancellationToken cancellationToken = default)
     {
-        ArgumentNullException.ThrowIfNull(pdfBytes);
+        ArgumentNullException.ThrowIfNull(pdfStream, nameof(pdfStream));
+        
+        if (pdfStream.Length == 0)
+            throw new ArgumentException("PDF stream is empty.", nameof(pdfStream));
 
-        try
+        // Defensive validation: Seekable streams must be at Position = 0
+        // Non-seekable streams (e.g., NetworkStream) are not checked
+        if (pdfStream.CanSeek && pdfStream.Position != 0)
+            throw new BadRequestException(null, new ArgumentException(
+                "PDF stream must be positioned at the beginning (Position = 0).",
+                nameof(pdfStream)));
+
+        using var pdfDocument = new PdfDocumentProcessor();
+        pdfDocument.LoadDocument(pdfStream);
+
+        if (pdfDocument.Document.Pages.Count == 0)
+            throw new ArgumentException("PDF document contains no pages.", nameof(pdfStream));
+
+        // Determine which pages to scan
+        int[] pagesToScan = DeterminePageNumbers(pdfDocument.Document.Pages.Count, pageNumbers);
+
+        // Extract all images from specified pages (no pre-filtering)
+        var allImages = new ConcurrentBag<(int pageNumber, DXBitmap image)>();
+
+        foreach (int pageNumber in pagesToScan)
         {
-            using var pdfDocument = new PdfDocumentProcessor();
-            pdfDocument.LoadDocument(new MemoryStream(pdfBytes));
+            cancellationToken.ThrowIfCancellationRequested();
 
-            if (pdfDocument.Document.Pages.Count == 0)
+            // Define area: entire page
+            var page = pdfDocument.Document.Pages[pageNumber - 1];
+            var area = new PdfDocumentArea(pageNumber,
+                new PdfRectangle(0, 0, page.CropBox.Width, page.CropBox.Height));
+
+            // Extract images from this page
+            var images = pdfDocument.GetDXImages(area);
+
+            foreach (var image in images)
             {
-                throw new ArgumentException("PDF document contains no pages.", nameof(pdfBytes));
+                // Collect ALL images - QRCodeDecoder will determine if it's a QR code
+                allImages.Add((pageNumber, image));
             }
+        }
 
-            // Get last page
-            int lastPageIndex = pdfDocument.Document.Pages.Count - 1;
+        if (allImages.IsEmpty)
+            throw new NotFoundException($"No images found in pages: {string.Join(", ", pagesToScan)}");
 
-            // Convert last page to image for QR code detection
-            using var pageImage = RenderPageToImage(pdfDocument, lastPageIndex);
-
-            // Detect and decode QR code
-            string? qrCodeContent = DecodeQrCodeFromImage(pageImage);
-
-            if (string.IsNullOrEmpty(qrCodeContent))
+        // Parallel scan all images
+        var qrCodeTasks = allImages.Select(imageData =>
+            Task.Run(() =>
             {
-                throw new SwissQrCodeNotFoundException(
-                    $"No QR Code found on the last page (page {lastPageIndex + 1}) of the PDF document.");
-            }
+                using (imageData.image)
+                {
+                    string? qrText = DecodeQrCodeFromImage(imageData.image);
+                    if (!string.IsNullOrEmpty(qrText))
+                    {
+                        try
+                        {
+                            // Parse with Codecrete
+                            var bill = QRBill.DecodeQrCodeText(qrText);
 
-            // Parse Swiss QR Bill content using Codecrete library
-            SwissQrCodeData qrCodeData = ParseSwissQrBillContent(qrCodeContent);
+                            // Split raw text into lines (handle both \r\n and \n)
+                            // Remove leading/trailing \r and \n from each line
+                            var rawLines = qrText
+                                .Split(["\r\n", "\n"], StringSplitOptions.None)
+                                .Select(line => line.Trim('\r', '\n'))
+                                .ToArray();
 
-            return await Task.FromResult(qrCodeData);
-        }
-        catch (SwissQrCodeNotFoundException)
+                            return (success: true, bill, rawLines, imageData.pageNumber);
+                        }
+                        catch
+                        {
+                            // Not a valid Swiss QR Bill, ignore
+                            return (success: false, bill: (Bill?)null, rawLines: (string[]?)null, pageNumber: 0);
+                        }
+                    }
+                    return (success: false, bill: (Bill?)null, rawLines: (string[]?)null, pageNumber: 0);
+                }
+            }, cancellationToken)
+        ).ToList();
+
+        // Wait for all tasks and find first valid Swiss QR
+        var results = await Task.WhenAll(qrCodeTasks);
+        var validResult = results.FirstOrDefault(r => r.success);
+
+        if (validResult.success && validResult.bill != null)
         {
-            throw;
-        }
-        catch (Exception ex)
-        {
-            throw new ArgumentException("Failed to extract Swiss QR Code from PDF.", nameof(pdfBytes), ex);
+            return (validResult.bill, validResult.rawLines!);
         }
+
+        throw new NotFoundException(
+            $"No valid Swiss QR Code found in {allImages.Count} images across pages: {string.Join(", ", pagesToScan)}.");
     }
 
     /// <summary>
-    /// Renders a PDF page to a high-resolution bitmap for QR code detection
+    /// Determines which pages to scan based on optional page numbers parameter.
+    /// Default: Last page first, then all pages in reverse order.
     /// </summary>
-    private static DXBitmap RenderPageToImage(PdfDocumentProcessor processor, int pageIndex)
+    private static int[] DeterminePageNumbers(int totalPages, int[]? pageNumbers)
     {
-        // Render page at high DPI for better QR code recognition
-        var pageImage = processor.CreateDXBitmap(pageIndex + 1, QrCodeSearchDpi);
-        return pageImage;
+        if (pageNumbers != null && pageNumbers.Length > 0)
+        {
+            // Validate page numbers
+            foreach (int pageNum in pageNumbers)
+                if (pageNum < 1 || pageNum > totalPages)
+                    throw new ArgumentException(
+                        $"Invalid page number {pageNum}. Document has {totalPages} pages.",
+                        nameof(pageNumbers));
+            return pageNumbers;
+        }
+
+        // Default: Scan all pages, last page first (Swiss QR standard)
+        return [.. Enumerable.Range(1, totalPages).OrderByDescending(p => p)];
     }
 
     /// <summary>
-    /// Decodes QR code from a DXBitmap image using ZXing library
+    /// Decodes QR code from a DXBitmap image using SkiaSharp.QrCode.
+    /// Converts DXBitmap to SKBitmap and attempts decoding.
     /// </summary>
-    [SupportedOSPlatform("windows")]
     private static string? DecodeQrCodeFromImage(DXBitmap dxImage)
     {
-        // Convert DXBitmap to System.Drawing.Bitmap via MemoryStream
+        // Convert DXBitmap to SKBitmap via MemoryStream (PNG format)
         using var ms = new MemoryStream();
         dxImage.Save(ms, DXImageFormat.Png);
         ms.Position = 0;
 
-        using var gdiImage = Image.FromStream(ms);
-        using var gdiBitmap = new Bitmap(gdiImage);
+        // Decode using SkiaSharp.QrCode
+        using var skBitmap = SKBitmap.Decode(ms);
+        if (skBitmap == null)
+            return null;
 
-        var reader = new ZXing.Windows.Compatibility.BarcodeReader
-        {
-            AutoRotate = true,
-            Options = new ZXing.Common.DecodingOptions
-            {
-                PossibleFormats = [BarcodeFormat.QR_CODE],
-                TryHarder = true,
-                TryInverted = true
-            }
-        };
-
-        var result = reader.Decode(gdiBitmap);
-        return result?.Text;
-    }
-
-    /// <summary>
-    /// Parses Swiss QR Bill content using Codecrete library
-    /// </summary>
-    private static SwissQrCodeData ParseSwissQrBillContent(string qrCodeText)
-    {
-        try
-        {
-            // Decode Swiss QR Bill using Codecrete library
-            var bill = QRBill.DecodeQrCodeText(qrCodeText);
-
-            // Determine reference type based on presence and format of reference
-            string referenceType = DetermineReferenceType(bill.Reference);
-
-            // Map AlternativeSchemes to string array
-            var alternativeParams = bill.AlternativeSchemes?
-                .Select(s => $"{s.Name}: {s.Instruction}")
-                .ToArray();
-
-            // Map to our domain value object
-            return new SwissQrCodeData
-            {
-                QrType = "SPC", // Always SPC for Swiss Payment Code
-                Version = bill.Version.ToString("D4"), // e.g., "0200" for version 2.0
-                CodingType = "1", // Always UTF-8
-                Iban = bill.Account ?? string.Empty,
-                Creditor = MapAddress(bill.Creditor),
-                UltimateCreditor = null, // Not exposed in Codecrete Bill model
-                Amount = bill.Amount,
-                Currency = bill.Currency ?? "CHF",
-                UltimateDebtor = bill.Debtor != null ? MapAddress(bill.Debtor) : null,
-                ReferenceType = referenceType,
-                Reference = bill.Reference,
-                UnstructuredMessage = bill.UnstructuredMessage,
-                BillInformation = bill.BillInformation,
-                AlternativeProcedureParameters = alternativeParams
-            };
-        }
-        catch (Exception ex)
-        {
-            throw new ArgumentException(
-                "Failed to parse Swiss QR Code content. The QR code may not be a valid Swiss QR Bill.", "qrCodeText", ex);
-        }
-    }
-
-    /// <summary>
-    /// Determines reference type based on reference string format
-    /// </summary>
-    private static string DetermineReferenceType(string? reference)
-    {
-        if (string.IsNullOrWhiteSpace(reference))
-            return "NON";
-
-        // QRR (QR Reference): 27 digits
-        if (reference.Length == 27 && reference.All(char.IsDigit))
-            return "QRR";
-
-        // SCOR (Creditor Reference ISO 11649): starts with RF and has check digits
-        if (reference.StartsWith("RF", StringComparison.OrdinalIgnoreCase) && reference.Length >= 5)
-            return "SCOR";
-
-        return "NON";
-    }
-
-    /// <summary>
-    /// Maps Codecrete Address to our AddressData value object.
-    /// 
-    /// NOTE: AddressLine1 and AddressLine2 (Combined Address / K-Type) are deprecated 
-    /// as of Swiss Payment Standards 2025 (effective 21 Nov 2025). 
-    /// The Swiss QR Bill now mandates Structured Address (S-Type) format.
-    /// These fields are retained for backward compatibility with legacy QR codes 
-    /// generated before the deprecation date.
-    /// </summary>
-    private static AddressData MapAddress(Codecrete.SwissQRBill.Generator.Address address)
-    {
-        return new AddressData
-        {
-            AddressType = address.Type == Codecrete.SwissQRBill.Generator.Address.AddressType.Structured ? "S" : "K",
-            Name = address.Name ?? string.Empty,
-            Street = address.Street,
-            BuildingNumber = address.HouseNo,
-#pragma warning disable CS0618 // AddressLine1/AddressLine2 obsolete but required for backward compatibility
-            AddressLine1 = address.AddressLine1,
-            AddressLine2 = address.AddressLine2,
-#pragma warning restore CS0618
-            PostalCode = address.PostalCode ?? string.Empty,
-            City = address.Town ?? string.Empty,
-            Country = address.CountryCode ?? string.Empty
-        };
+        // TryDecode returns true if QR code found and decoded successfully
+        bool success = QRCodeDecoder.TryDecode(skBitmap, out var text, out _);
+        return success ? text : null;
     }
 }

DocumentOperator.Infrastructure/Services/StringExtensions.cs

@@ -0,0 +1,16 @@
+using System.Xml.Serialization;
+
+namespace DocumentService.Infrastructure.Services;
+
+public static class StringExtensions
+{
+    public static T? DeserializeXml<T>(this string xmlText)
+    {
+        if (string.IsNullOrWhiteSpace(xmlText))
+            return default;
+
+        var serializer = new XmlSerializer(typeof(T));
+        using var reader = new StringReader(xmlText);
+        return (T?)serializer.Deserialize(reader);
+    }
+}

DocumentOperator.Tests/DocumentService.Tests.csproj

@@ -39,10 +39,11 @@
   </ItemGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\DocumentOperator.API\DocumentOperator.API.csproj" />
-    <ProjectReference Include="..\DocumentOperator.Domain\DocumentOperator.Domain.csproj" />
-    <ProjectReference Include="..\DocumentOperator.Application\DocumentOperator.Application.csproj" />
-    <ProjectReference Include="..\DocumentOperator.Infrastructure\DocumentOperator.Infrastructure.csproj" />
+    <ProjectReference Include="..\DocumentOperator.API\DocumentService.API.csproj" />
+    <ProjectReference Include="..\DocumentOperator.Domain\DocumentService.Domain.csproj" />
+    <ProjectReference Include="..\DocumentOperator.Application\DocumentService.Application.csproj" />
+    <ProjectReference Include="..\DocumentOperator.Infrastructure\DocumentService.Infrastructure.csproj" />
+    <ProjectReference Include="..\DocumentService.Client\DocumentService.Client.csproj" />
   </ItemGroup>
 
 </Project>

DocumentOperator.Tests/Integration/API/ExtractSwissQrCodeEndpointTests.cs

@@ -1,5 +1,5 @@
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.SwissQrCode.Queries;
+using DocumentService.API.Controllers; // For ExtractSwissQrCodeBase64Request DTO
+using DocumentService.Application.Common.DTOs;
 using FluentAssertions;
 using Microsoft.AspNetCore.Mvc.Testing;
 using System.Net;
@@ -7,7 +7,7 @@ using System.Net.Http.Json;
 using System.Text.Json;
 using Xunit;
 
-namespace DocumentOperator.Tests.Integration.API;
+namespace DocumentService.Tests.Integration.API;
 
 public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicationFactory<Program>>
 {
@@ -27,11 +27,10 @@ public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicati
     public async Task POST_ExtractSwissQrCode_ValidRequest_Returns200()
     {
         // Arrange
-        var validPdfBase64 = GetEmbeddedResourceAsBase64("DocumentOperator.Tests.TestData.Pdfs.valid.pdf");
+        var validPdfBase64 = GetEmbeddedResourceAsBase64("DocumentService.Tests.TestData.Pdfs.valid.pdf");
 
-        var request = new ExtractSwissQrCodeQuery
+        var request = new ExtractSwissQrCodeBase64Request
         {
-            References = new List<string> { "REF-001", "REF-002" },
             Base64Pdf = validPdfBase64
         };
 
@@ -48,8 +47,8 @@ public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicati
         {
             var result = await response.Content.ReadFromJsonAsync<SwissQrCodeExtractionResult>(_jsonOptions);
             result.Should().NotBeNull();
-            result!.References.Should().BeEquivalentTo(new[] { "REF-001", "REF-002" });
-            result.QrCodeData.Should().NotBeNull();
+            result.Bill.Should().NotBeNull();
+            result.RawLines.Should().NotBeEmpty();
         }
     }
 
@@ -57,9 +56,8 @@ public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicati
     public async Task POST_ExtractSwissQrCode_InvalidBase64_Returns400()
     {
         // Arrange
-        var request = new ExtractSwissQrCodeQuery
+        var request = new ExtractSwissQrCodeBase64Request
         {
-            References = new List<string> { "REF-001" },
             Base64Pdf = "INVALID_BASE64!!!"
         };
 
@@ -68,6 +66,10 @@ public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicati
 
         // Assert
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+        
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // FormatException message contains "Base-64" (with hyphen)
+        problemDetails.Should().MatchRegex("(?i)base.?64", "should contain Base64 validation error");
     }
 
     [Fact]
@@ -75,7 +77,7 @@ public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicati
     {
         // Arrange: References are OPTIONAL - null should not cause validation error (400)
         // Using pdfWithSwissQRCode.pdf which actually has a QR code, so we get 200
-        var validPdfBase64 = GetEmbeddedResourceAsBase64("DocumentOperator.Tests.TestData.Pdfs.pdfWithSwissQRCode.pdf");
+        var validPdfBase64 = GetEmbeddedResourceAsBase64("DocumentService.Tests.TestData.Pdfs.pdfWithSwissQRCode.pdf");
 
         var request = new
         {
@@ -95,7 +97,6 @@ public sealed class ExtractSwissQrCodeEndpointTests : IClassFixture<WebApplicati
         {
             var result = await response.Content.ReadFromJsonAsync<SwissQrCodeExtractionResult>();
             result.Should().NotBeNull();
-            result!.References.Should().BeEmpty(); // Null input → empty output array
         }
     }
 

DocumentOperator.Tests/Integration/API/PdfAttachmentControllerTests.cs

@@ -0,0 +1,383 @@
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Client.Models.Requests;
+using FluentAssertions;
+using Microsoft.AspNetCore.Mvc.Testing;
+using System.Net;
+using System.Net.Http.Json;
+using Xunit;
+
+namespace DocumentService.Tests.Integration.API;
+
+/// <summary>
+/// Integration tests for PdfAttachmentController.
+/// Tests /api/pdf/attachments/check endpoint with both multipart and Base64 input.
+/// </summary>
+public class PdfAttachmentControllerTests : IClassFixture<WebApplicationFactory<Program>>
+{
+    private readonly WebApplicationFactory<Program> _factory;
+    private readonly HttpClient _client;
+
+    public PdfAttachmentControllerTests(WebApplicationFactory<Program> factory)
+    {
+        _factory = factory;
+        _client = _factory.CreateClient();
+    }
+
+    #region Helper Methods
+
+    /// <summary>
+    /// Loads a test PDF from embedded resources.
+    /// </summary>
+    private static async Task<byte[]> LoadTestPdfAsync(string filename)
+    {
+        var assembly = typeof(PdfAttachmentControllerTests).Assembly;
+        var resourceName = $"DocumentService.Tests.TestData.Pdfs.{filename}";
+
+        using var stream = assembly.GetManifestResourceStream(resourceName);
+        if (stream == null)
+        {
+            throw new InvalidOperationException($"Test resource '{resourceName}' not found");
+        }
+
+        using var ms = new MemoryStream();
+        await stream.CopyToAsync(ms);
+        return ms.ToArray();
+    }
+
+    #endregion
+
+    #region Base64 JSON Tests
+
+    [Fact]
+    public async Task POST_CheckAttachments_Base64_PdfWithoutAttachments_Returns200()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithSwissQRCode.pdf");
+        string base64Pdf = Convert.ToBase64String(pdfBytes);
+        var request = new CheckPdfAttachmentsRequest { Base64Pdf = base64Pdf };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/check", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<AttachmentCheckResult>();
+        result.Should().NotBeNull();
+        result!.HasAttachments.Should().BeFalse();
+        result.AttachmentCount.Should().Be(0);
+        result.Attachments.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task POST_CheckAttachments_Base64_PdfWithMultipleAttachments_Returns200()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithMoreThanOneAttachment.pdf");
+        string base64Pdf = Convert.ToBase64String(pdfBytes);
+        var request = new CheckPdfAttachmentsRequest { Base64Pdf = base64Pdf };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/check", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<AttachmentCheckResult>();
+        result.Should().NotBeNull();
+        result!.HasAttachments.Should().BeTrue();
+        result.AttachmentCount.Should().Be(6, "PDF has exactly 6 attachments");
+        result.Attachments.Should().HaveCount(6);
+
+        // Verify each attachment has required properties
+        foreach (var attachment in result.Attachments)
+        {
+            attachment.FileName.Should().NotBeNullOrEmpty();
+            attachment.MimeType.Should().NotBeNullOrEmpty();
+            attachment.Size.Should().BeGreaterThan(0);
+        }
+    }
+
+    [Fact]
+    public async Task POST_CheckAttachments_Base64_InvalidBase64_Returns400()
+    {
+        // Arrange
+        var request = new CheckPdfAttachmentsRequest { Base64Pdf = "invalid-base64!!!" };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/check", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // FormatException message contains "Base-64" (with hyphen)
+        problemDetails.Should().MatchRegex("(?i)base.?64", "should contain Base64 validation error");
+    }
+
+    [Fact]
+    public async Task POST_CheckAttachments_Base64_EmptyPdf_Returns400()
+    {
+        // Arrange
+        var request = new CheckPdfAttachmentsRequest { Base64Pdf = string.Empty };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/check", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // Empty Base64 causes FormatException or empty stream error
+        problemDetails.Should().MatchRegex("(Base64|empty|stream)", "should contain validation error message");
+    }
+
+    #endregion
+
+    #region Multipart/Form-Data Tests
+
+    [Fact]
+    public async Task POST_CheckAttachments_Multipart_PdfWithoutAttachments_Returns200()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithSwissQRCode.pdf");
+
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(pdfBytes);
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "pdfWithSwissQRCode.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/check", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<AttachmentCheckResult>();
+        result.Should().NotBeNull();
+        result!.HasAttachments.Should().BeFalse();
+        result.AttachmentCount.Should().Be(0);
+        result.Attachments.Should().BeEmpty();
+    }
+
+    [Fact]
+    public async Task POST_CheckAttachments_Multipart_PdfWithMultipleAttachments_Returns200()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithMoreThanOneAttachment.pdf");
+
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(pdfBytes);
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "pdfWithMoreThanOneAttachment.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/check", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<AttachmentCheckResult>();
+        result.Should().NotBeNull();
+        result!.HasAttachments.Should().BeTrue();
+        result.AttachmentCount.Should().Be(6);
+        result.Attachments.Should().HaveCount(6);
+
+        // Verify first attachment details
+        var firstAttachment = result.Attachments.First();
+        firstAttachment.FileName.Should().NotBeNullOrEmpty();
+        firstAttachment.MimeType.Should().NotBeNullOrEmpty();
+        firstAttachment.Size.Should().BeGreaterThan(0);
+    }
+
+    [Fact]
+    public async Task POST_CheckAttachments_Multipart_MissingFile_Returns400()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent(); // No file added
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/check", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task POST_CheckAttachments_Multipart_CorruptedPdf_Returns500()
+    {
+        // Arrange
+        byte[] corruptedBytes = "This is not a valid PDF content"u8.ToArray();
+
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(corruptedBytes);
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "corrupted.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/check", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.InternalServerError);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // Note: Generic error message for security reasons (doesn't expose internal details)
+        problemDetails.Should().Contain("error");
+    }
+
+    #endregion
+
+    #region Edge Cases
+
+    [Fact]
+    public async Task POST_CheckAttachments_Base64_PdfWithSwissQrCode_Returns200()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithSwissQRCode.pdf");
+        string base64Pdf = Convert.ToBase64String(pdfBytes);
+        var request = new CheckPdfAttachmentsRequest { Base64Pdf = base64Pdf };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/check", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<AttachmentCheckResult>();
+        result.Should().NotBeNull();
+        result!.HasAttachments.Should().BeFalse("Swiss QR PDF has no attachments");
+        result.AttachmentCount.Should().Be(0);
+    }
+
+    #endregion
+
+    #region Extract Attachments Tests (Multipart)
+
+    [Fact]
+    public async Task POST_ExtractAttachments_Multipart_ValidPdfWithAttachments_Returns200WithZip()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithMoreThanOneAttachment.pdf");
+
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(pdfBytes);
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "test.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/extract", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        response.Content.Headers.ContentType?.MediaType.Should().Be("application/zip");
+        response.Content.Headers.ContentDisposition?.FileName.Should().Be("attachments.zip");
+
+        byte[] zipBytes = await response.Content.ReadAsByteArrayAsync();
+        zipBytes.Should().NotBeEmpty("ZIP should contain data");
+
+        // Verify ZIP structure
+        using var zipStream = new MemoryStream(zipBytes);
+        using var zipArchive = new System.IO.Compression.ZipArchive(zipStream, System.IO.Compression.ZipArchiveMode.Read);
+        
+        zipArchive.Entries.Should().HaveCount(6, "PDF contains 6 attachments");
+    }
+
+    [Fact]
+    public async Task POST_ExtractAttachments_Multipart_EmptyPdf_Returns400()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(Array.Empty<byte>());
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "empty.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/extract", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task POST_ExtractAttachments_Multipart_CorruptedPdf_Returns500()
+    {
+        // Arrange
+        byte[] corruptedBytes = "This is not a valid PDF content"u8.ToArray();
+
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(corruptedBytes);
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "corrupted.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/attachments/extract", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.InternalServerError);
+    }
+
+    #endregion
+
+    #region Extract Attachments Tests (Base64)
+
+    [Fact]
+    public async Task POST_ExtractAttachments_Base64_ValidPdfWithAttachments_Returns200WithZip()
+    {
+        // Arrange
+        byte[] pdfBytes = await LoadTestPdfAsync("pdfWithMoreThanOneAttachment.pdf");
+        string base64Pdf = Convert.ToBase64String(pdfBytes);
+        var request = new ExtractPdfAttachmentsRequest { Base64Pdf = base64Pdf };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/extract", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        response.Content.Headers.ContentType?.MediaType.Should().Be("application/zip");
+        response.Content.Headers.ContentDisposition?.FileName.Should().Be("attachments.zip");
+
+        byte[] zipBytes = await response.Content.ReadAsByteArrayAsync();
+        zipBytes.Should().NotBeEmpty("ZIP should contain data");
+
+        // Verify ZIP structure
+        using var zipStream = new MemoryStream(zipBytes);
+        using var zipArchive = new System.IO.Compression.ZipArchive(zipStream, System.IO.Compression.ZipArchiveMode.Read);
+        
+        zipArchive.Entries.Should().HaveCount(6, "PDF contains 6 attachments");
+    }
+
+    [Fact]
+    public async Task POST_ExtractAttachments_Base64_InvalidBase64_Returns400()
+    {
+        // Arrange
+        var request = new ExtractPdfAttachmentsRequest { Base64Pdf = "invalid-base64!!!" };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/extract", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // FormatException message contains "Base-64" (with hyphen)
+        problemDetails.Should().MatchRegex("(?i)base.?64", "should contain Base64 validation error");
+    }
+
+    [Fact]
+    public async Task POST_ExtractAttachments_Base64_EmptyPdf_Returns400()
+    {
+        // Arrange
+        var request = new ExtractPdfAttachmentsRequest { Base64Pdf = string.Empty };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/attachments/extract", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        problemDetails.Should().MatchRegex("(Base64|empty|stream)", "should contain validation error message");
+    }
+
+    #endregion
+}

DocumentOperator.Tests/Integration/API/PdfOperationsControllerTests.cs

@@ -0,0 +1,500 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Reflection;
+using System.Text;
+using System.Text.Json;
+using DocumentService.API.Controllers;
+using DocumentService.Domain.Models.ValueObjects;
+using FluentAssertions;
+using Microsoft.AspNetCore.Mvc.Testing;
+
+namespace DocumentService.Tests.Integration.API;
+
+public class PdfOperationsControllerTests : IClassFixture<WebApplicationFactory<Program>>
+{
+    private readonly HttpClient _client;
+
+    public PdfOperationsControllerTests(WebApplicationFactory<Program> factory)
+    {
+        _client = factory.CreateClient();
+    }
+
+    private static Stream LoadTestPdfAsStream(string fileName)
+    {
+        var assembly = Assembly.GetExecutingAssembly();
+        var resourceName = $"DocumentService.Tests.TestData.Pdfs.{fileName}";
+        return assembly.GetManifestResourceStream(resourceName) 
+               ?? throw new FileNotFoundException($"Embedded resource not found: {resourceName}");
+    }
+
+    private static string LoadTestPdfAsBase64(string fileName)
+    {
+        using var stream = LoadTestPdfAsStream(fileName);
+        using var ms = new MemoryStream();
+        stream.CopyTo(ms);
+        return Convert.ToBase64String(ms.ToArray());
+    }
+
+    #region Merge Endpoint Tests (existing - keeping for reference)
+
+    [Fact]
+    public async Task MergeFromFiles_ValidPdfs_ReturnsMergedPdf()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        
+        using var pdf1Stream = LoadTestPdfAsStream("valid.pdf");
+        using var pdf2Stream = LoadTestPdfAsStream("valid.pdf");
+        
+        var pdf1Content = new StreamContent(pdf1Stream);
+        var pdf2Content = new StreamContent(pdf2Stream);
+        
+        pdf1Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        pdf2Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        
+        content.Add(pdf1Content, "files", "file1.pdf");
+        content.Add(pdf2Content, "files", "file2.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        response.Content.Headers.ContentType?.MediaType.Should().Be("application/pdf");
+        
+        byte[] mergedPdf = await response.Content.ReadAsByteArrayAsync();
+        mergedPdf.Should().NotBeEmpty();
+        mergedPdf.Length.Should().BeGreaterThan(100); // Sanity check
+    }
+
+    [Fact]
+    public async Task MergeFromBase64_ValidPdfs_ReturnsMergedPdf()
+    {
+        // Arrange
+        string base64Pdf1 = LoadTestPdfAsBase64("valid.pdf");
+        string base64Pdf2 = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new MergePdfsBase64Request
+        {
+            Base64Pdfs = new List<string> { base64Pdf1, base64Pdf2 },
+            PageRanges = null
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        byte[] mergedPdf = await response.Content.ReadAsByteArrayAsync();
+        mergedPdf.Should().NotBeEmpty();
+    }
+
+    [Fact]
+    public async Task MergeFromBase64_WithPageRanges_ReturnsMergedPdf()
+    {
+        // Arrange
+        string base64Pdf1 = LoadTestPdfAsBase64("valid.pdf");
+        string base64Pdf2 = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new MergePdfsBase64Request
+        {
+            Base64Pdfs = new List<string> { base64Pdf1, base64Pdf2 },
+            PageRanges = new List<string?> { "1", "1" } // Only first page from each
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        byte[] mergedPdf = await response.Content.ReadAsByteArrayAsync();
+        mergedPdf.Should().NotBeEmpty();
+    }
+
+    [Fact]
+    public async Task MergeFromFiles_OnePdf_Returns400()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        using var pdfStream = LoadTestPdfAsStream("valid.pdf");
+        var pdfContent = new StreamContent(pdfStream);
+        pdfContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        content.Add(pdfContent, "files", "file1.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task MergeFromBase64_InvalidBase64_Returns400()
+    {
+        // Arrange
+        var request = new MergePdfsBase64Request
+        {
+            Base64Pdfs = new List<string> { "INVALID_BASE64!!!", "ANOTHER_INVALID" }
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task MergeFromBase64_InvalidPageRange_Returns400()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new MergePdfsBase64Request
+        {
+            Base64Pdfs = new List<string> { base64Pdf, base64Pdf },
+            PageRanges = new List<string?> { "999-1000", null } // Exceeds page count
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task MergeFromFiles_CorruptedPdf_Returns500()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        
+        byte[] corruptedData = "NOT A PDF FILE"u8.ToArray();
+        var corruptedContent = new ByteArrayContent(corruptedData);
+        corruptedContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        
+        using var validPdfStream = LoadTestPdfAsStream("valid.pdf");
+        var validContent = new StreamContent(validPdfStream);
+        validContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        
+        content.Add(corruptedContent, "files", "corrupted.pdf");
+        content.Add(validContent, "files", "valid.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/merge", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.InternalServerError);
+    }
+
+    #endregion
+
+    #region Annotate Endpoint Tests
+
+    [Fact]
+    public async Task AnnotateFromFile_TextMarkupHighlight_ReturnsAnnotatedPdf()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        
+        using var pdfStream = LoadTestPdfAsStream("valid.pdf");
+        var pdfContent = new StreamContent(pdfStream);
+        pdfContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        content.Add(pdfContent, "file", "test.pdf");
+        
+        content.Add(new StringContent(AnnotationType.TextMarkup.ToString()), "annotationType");
+        content.Add(new StringContent("1"), "pageNumber");
+        content.Add(new StringContent("100"), "x1");
+        content.Add(new StringContent("100"), "y1");
+        content.Add(new StringContent("200"), "x2");
+        content.Add(new StringContent("120"), "y2");
+        content.Add(new StringContent("Important text"), "content");
+        content.Add(new StringContent("Test Author"), "author");
+        content.Add(new StringContent("FFFF00"), "color");
+        content.Add(new StringContent(TextMarkupStyle.Highlight.ToString()), "textMarkupStyle");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        response.Content.Headers.ContentType?.MediaType.Should().Be("application/pdf");
+        
+        byte[] annotatedPdf = await response.Content.ReadAsByteArrayAsync();
+        annotatedPdf.Should().NotBeEmpty();
+        annotatedPdf.Length.Should().BeGreaterThan(100);
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_FreeText_ReturnsAnnotatedPdf()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.FreeText,
+            PageNumber = 1,
+            X1 = 50,
+            Y1 = 50,
+            X2 = 150,
+            Y2 = 100,
+            Content = "Free text annotation",
+            Author = "John Doe",
+            Color = "FF0000"
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        byte[] annotatedPdf = await response.Content.ReadAsByteArrayAsync();
+        annotatedPdf.Should().NotBeEmpty();
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_StickyNote_ReturnsAnnotatedPdf()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.StickyNote,
+            PageNumber = 1,
+            X1 = 300,
+            Y1 = 300,
+            X2 = 320,
+            Y2 = 320,
+            Content = "Please review this section",
+            Author = "Reviewer"
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        byte[] annotatedPdf = await response.Content.ReadAsByteArrayAsync();
+        annotatedPdf.Should().NotBeEmpty();
+    }
+
+    [Fact]
+    public async Task AnnotateFromFile_Circle_ReturnsAnnotatedPdf()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        
+        using var pdfStream = LoadTestPdfAsStream("valid.pdf");
+        var pdfContent = new StreamContent(pdfStream);
+        pdfContent.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
+        content.Add(pdfContent, "file", "test.pdf");
+        
+        content.Add(new StringContent(AnnotationType.Circle.ToString()), "annotationType");
+        content.Add(new StringContent("1"), "pageNumber");
+        content.Add(new StringContent("100"), "x1");
+        content.Add(new StringContent("200"), "y1");
+        content.Add(new StringContent("200"), "x2");
+        content.Add(new StringContent("300"), "y2");
+        content.Add(new StringContent("Circle annotation"), "content");
+        content.Add(new StringContent("00FF00"), "color");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        byte[] annotatedPdf = await response.Content.ReadAsByteArrayAsync();
+        annotatedPdf.Should().NotBeEmpty();
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_Square_ReturnsAnnotatedPdf()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.Square,
+            PageNumber = 1,
+            X1 = 250,
+            Y1 = 250,
+            X2 = 350,
+            Y2 = 350,
+            Color = "0000FF"
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+        byte[] annotatedPdf = await response.Content.ReadAsByteArrayAsync();
+        annotatedPdf.Should().NotBeEmpty();
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_InvalidBase64_Returns400()
+    {
+        // Arrange
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = "INVALID_BASE64!!!",
+            AnnotationType = AnnotationType.Circle,
+            PageNumber = 1,
+            X1 = 0,
+            Y1 = 0,
+            X2 = 100,
+            Y2 = 100
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_InvalidPageNumber_Returns400()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.FreeText,
+            PageNumber = 999, // Exceeds page count
+            X1 = 0,
+            Y1 = 0,
+            X2 = 100,
+            Y2 = 100,
+            Content = "Test"
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_FreeTextWithoutContent_Returns400()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.FreeText,
+            PageNumber = 1,
+            X1 = 0,
+            Y1 = 0,
+            X2 = 100,
+            Y2 = 100
+            // Missing required Content
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_TextMarkupWithoutStyle_Returns400()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.TextMarkup,
+            PageNumber = 1,
+            X1 = 0,
+            Y1 = 0,
+            X2 = 100,
+            Y2 = 100
+            // Missing required TextMarkupStyle
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task AnnotateFromBase64_InvalidColorFormat_Returns400()
+    {
+        // Arrange
+        string base64Pdf = LoadTestPdfAsBase64("valid.pdf");
+
+        var request = new AddAnnotationBase64Command
+        {
+            Base64Pdf = base64Pdf,
+            AnnotationType = AnnotationType.Circle,
+            PageNumber = 1,
+            X1 = 0,
+            Y1 = 0,
+            X2 = 100,
+            Y2 = 100,
+            Color = "INVALID" // Invalid hex format
+        };
+
+        var json = JsonSerializer.Serialize(request);
+        var content = new StringContent(json, Encoding.UTF8, "application/json");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/operations/annotate", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    #endregion
+}

DocumentOperator.Tests/Integration/API/PdfValidationControllerTests.cs

@@ -1,12 +1,12 @@
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.ValidatePdf.Queries;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Client.Models.Requests;
 using FluentAssertions;
 using Microsoft.AspNetCore.Mvc.Testing;
 using System.Net;
 using System.Net.Http.Json;
 using Xunit;
 
-namespace DocumentOperator.Tests.Integration.API;
+namespace DocumentService.Tests.Integration.API;
 
 public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<Program>>
 {
@@ -27,7 +27,7 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
         // Arrange
         // Verwende ein echtes Test-PDF (embedded resource aus Unit Tests)
         var assembly = typeof(PdfValidationControllerTests).Assembly;
-        var resourceName = "DocumentOperator.Tests.TestData.Pdfs.valid.pdf";
+        var resourceName = "DocumentService.Tests.TestData.Pdfs.valid.pdf";
 
         byte[] pdfBytes;
         using (var stream = assembly.GetManifestResourceStream(resourceName))
@@ -43,7 +43,7 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
         }
 
         var base64Pdf = Convert.ToBase64String(pdfBytes);
-        var request = new ValidatePdfQuery { Base64Pdf = base64Pdf };
+        var request = new ValidatePdfBase64Request { Base64Pdf = base64Pdf };
 
         // Act
         var response = await _client.PostAsJsonAsync("/api/pdf/validation/validate", request);
@@ -62,7 +62,7 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
     public async Task POST_ValidatePdf_Base64_InvalidBase64_Returns400()
     {
         // Arrange
-        var request = new ValidatePdfQuery { Base64Pdf = "invalid-base64!!!" }; // Kein gültiges Base64
+        var request = new ValidatePdfBase64Request { Base64Pdf = "invalid-base64!!!" }; // Kein gültiges Base64
 
         // Act
         var response = await _client.PostAsJsonAsync("/api/pdf/validation/validate", request);
@@ -71,14 +71,15 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
 
         var problemDetails = await response.Content.ReadAsStringAsync();
-        problemDetails.Should().Contain("Base64");
+        // FormatException message contains "Base-64" (with hyphen)
+        problemDetails.Should().MatchRegex("(?i)base.?64", "should contain Base64 validation error");
     }
 
     [Fact]
     public async Task POST_ValidatePdf_Base64_EmptyPdf_Returns400()
     {
         // Arrange
-        var request = new ValidatePdfQuery { Base64Pdf = string.Empty }; // Leerer String
+        var request = new ValidatePdfBase64Request { Base64Pdf = string.Empty }; // Leerer String
 
         // Act
         var response = await _client.PostAsJsonAsync("/api/pdf/validation/validate", request);
@@ -87,7 +88,8 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
         response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
 
         var problemDetails = await response.Content.ReadAsStringAsync();
-        problemDetails.Should().Contain("Either PdfBytes or Base64Pdf must be provided");
+        // Empty Base64 causes FormatException or empty stream error
+        problemDetails.Should().MatchRegex("(Base64|empty|stream)", "should contain validation error message");
     }
 
     #endregion
@@ -99,7 +101,7 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
     {
         // Arrange
         var assembly = typeof(PdfValidationControllerTests).Assembly;
-        var resourceName = "DocumentOperator.Tests.TestData.Pdfs.valid.pdf";
+        var resourceName = "DocumentService.Tests.TestData.Pdfs.valid.pdf";
 
         byte[] pdfBytes;
         using (var stream = assembly.GetManifestResourceStream(resourceName))
@@ -166,4 +168,153 @@ public class PdfValidationControllerTests : IClassFixture<WebApplicationFactory<
     }
 
     #endregion
+
+    #region PDF/A Validation Tests (Base64)
+
+    [Fact]
+    public async Task POST_ValidatePdfA_Base64_ValidPdf_Returns200()
+    {
+        // Arrange
+        var assembly = typeof(PdfValidationControllerTests).Assembly;
+        var resourceName = "DocumentService.Tests.TestData.Pdfs.valid.pdf";
+
+        byte[] pdfBytes;
+        using (var stream = assembly.GetManifestResourceStream(resourceName))
+        {
+            if (stream == null)
+            {
+                throw new InvalidOperationException($"Test resource '{resourceName}' not found");
+            }
+
+            using var ms = new MemoryStream();
+            await stream.CopyToAsync(ms);
+            pdfBytes = ms.ToArray();
+        }
+
+        var base64Pdf = Convert.ToBase64String(pdfBytes);
+        var request = new ValidatePdfABase64Request { Base64Pdf = base64Pdf };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/validation/validate-pdfa", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<PdfAValidationResult>();
+        result.Should().NotBeNull();
+        result!.IsValid.Should().BeTrue();
+        result.PageCount.Should().BeGreaterThan(0);
+        result.PdfVersion.Should().NotBeNullOrEmpty();
+    }
+
+    [Fact]
+    public async Task POST_ValidatePdfA_Base64_InvalidBase64_Returns400()
+    {
+        // Arrange
+        var request = new ValidatePdfABase64Request { Base64Pdf = "invalid-base64!!!" };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/validation/validate-pdfa", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // FormatException message contains "Base-64" (with hyphen)
+        problemDetails.Should().MatchRegex("(?i)base.?64", "should contain Base64 validation error");
+    }
+
+    [Fact]
+    public async Task POST_ValidatePdfA_Base64_EmptyPdf_Returns400()
+    {
+        // Arrange
+        var request = new ValidatePdfABase64Request { Base64Pdf = string.Empty };
+
+        // Act
+        var response = await _client.PostAsJsonAsync("/api/pdf/validation/validate-pdfa", request);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        // Empty Base64 causes FormatException or empty stream error
+        problemDetails.Should().MatchRegex("(Base64|empty|stream)", "should contain validation error message");
+    }
+
+    #endregion
+
+    #region PDF/A Validation Tests (Multipart)
+
+    [Fact]
+    public async Task POST_ValidatePdfA_Multipart_ValidPdf_Returns200()
+    {
+        // Arrange
+        var assembly = typeof(PdfValidationControllerTests).Assembly;
+        var resourceName = "DocumentService.Tests.TestData.Pdfs.valid.pdf";
+
+        byte[] pdfBytes;
+        using (var stream = assembly.GetManifestResourceStream(resourceName))
+        {
+            if (stream == null)
+            {
+                throw new InvalidOperationException($"Test resource '{resourceName}' not found");
+            }
+
+            using var ms = new MemoryStream();
+            await stream.CopyToAsync(ms);
+            pdfBytes = ms.ToArray();
+        }
+
+        // Create multipart/form-data content
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(pdfBytes);
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "test.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/validation/validate-pdfa", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var result = await response.Content.ReadFromJsonAsync<PdfAValidationResult>();
+        result.Should().NotBeNull();
+        result!.IsValid.Should().BeTrue();
+        result.PageCount.Should().BeGreaterThan(0);
+        result.PdfVersion.Should().NotBeNullOrEmpty();
+    }
+
+    [Fact]
+    public async Task POST_ValidatePdfA_Multipart_EmptyFile_Returns400()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+        var fileContent = new ByteArrayContent(Array.Empty<byte>());
+        fileContent.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/pdf");
+        content.Add(fileContent, "file", "empty.pdf");
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/validation/validate-pdfa", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+
+        var problemDetails = await response.Content.ReadAsStringAsync();
+        problemDetails.Should().Contain("cannot be empty");
+    }
+
+    [Fact]
+    public async Task POST_ValidatePdfA_Multipart_NoFile_Returns400()
+    {
+        // Arrange
+        using var content = new MultipartFormDataContent();
+
+        // Act
+        var response = await _client.PostAsync("/api/pdf/validation/validate-pdfa", content);
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    #endregion
 }

DocumentOperator.Tests/TestData/Pdfs/attachment.xml

@@ -0,0 +1,152 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<rsm:CrossIndustryInvoice xmlns:rsm="urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100" xmlns:ram="urn:un:unece:uncefact:data:standard:ReusableAggregateBusinessInformationEntity:100" xmlns:udt="urn:un:unece:uncefact:data:standard:UnqualifiedDataType:100" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="urn:un:unece:uncefact:data:standard:CrossIndustryInvoice:100 ../../../schemas/UN_CEFACT/CrossIndustryInvoice_100pD16B.xsd">
+  <rsm:ExchangedDocumentContext>
+    <ram:GuidelineSpecifiedDocumentContextParameter>
+      <ram:ID>urn:cen.eu:en16931:2017</ram:ID>
+    </ram:GuidelineSpecifiedDocumentContextParameter>
+  </rsm:ExchangedDocumentContext>
+  <rsm:ExchangedDocument>
+    <ram:ID>2021_10</ram:ID>
+    <ram:TypeCode>380</ram:TypeCode>
+    <ram:IssueDateTime>
+      <udt:DateTimeString format="102">20210924</udt:DateTimeString>
+    </ram:IssueDateTime>
+  </rsm:ExchangedDocument>
+  <rsm:SupplyChainTradeTransaction>
+    <ram:IncludedSupplyChainTradeLineItem>
+      <ram:AssociatedDocumentLineDocument>
+        <ram:LineID>1</ram:LineID>
+      </ram:AssociatedDocumentLineDocument>
+      <ram:SpecifiedTradeProduct>
+        <ram:Name>Project management</ram:Name>
+        <ram:Description/>
+      </ram:SpecifiedTradeProduct>
+      <ram:SpecifiedLineTradeAgreement>
+        <ram:NetPriceProductTradePrice>
+          <ram:ChargeAmount>500.000000</ram:ChargeAmount>
+        </ram:NetPriceProductTradePrice>
+      </ram:SpecifiedLineTradeAgreement>
+      <ram:SpecifiedLineTradeDelivery>
+        <ram:BilledQuantity unitCode="C62">2.00</ram:BilledQuantity>
+      </ram:SpecifiedLineTradeDelivery>
+      <ram:SpecifiedLineTradeSettlement>
+        <ram:ApplicableTradeTax>
+          <ram:TypeCode>VAT</ram:TypeCode>
+          <ram:CategoryCode>S</ram:CategoryCode>
+          <ram:RateApplicablePercent>19.00</ram:RateApplicablePercent>
+        </ram:ApplicableTradeTax>
+        <ram:SpecifiedTradeSettlementLineMonetarySummation>
+          <ram:LineTotalAmount>1000.00</ram:LineTotalAmount>
+        </ram:SpecifiedTradeSettlementLineMonetarySummation>
+      </ram:SpecifiedLineTradeSettlement>
+    </ram:IncludedSupplyChainTradeLineItem>
+    <ram:IncludedSupplyChainTradeLineItem>
+      <ram:AssociatedDocumentLineDocument>
+        <ram:LineID>2</ram:LineID>
+      </ram:AssociatedDocumentLineDocument>
+      <ram:SpecifiedTradeProduct>
+        <ram:Name>Consulting</ram:Name>
+        <ram:Description/>
+      </ram:SpecifiedTradeProduct>
+      <ram:SpecifiedLineTradeAgreement>
+        <ram:NetPriceProductTradePrice>
+          <ram:ChargeAmount>40.000000</ram:ChargeAmount>
+        </ram:NetPriceProductTradePrice>
+      </ram:SpecifiedLineTradeAgreement>
+      <ram:SpecifiedLineTradeDelivery>
+        <ram:BilledQuantity unitCode="C62">5.00</ram:BilledQuantity>
+      </ram:SpecifiedLineTradeDelivery>
+      <ram:SpecifiedLineTradeSettlement>
+        <ram:ApplicableTradeTax>
+          <ram:TypeCode>VAT</ram:TypeCode>
+          <ram:CategoryCode>S</ram:CategoryCode>
+          <ram:RateApplicablePercent>19.00</ram:RateApplicablePercent>
+        </ram:ApplicableTradeTax>
+        <ram:SpecifiedTradeSettlementLineMonetarySummation>
+          <ram:LineTotalAmount>200.00</ram:LineTotalAmount>
+        </ram:SpecifiedTradeSettlementLineMonetarySummation>
+      </ram:SpecifiedLineTradeSettlement>
+    </ram:IncludedSupplyChainTradeLineItem>
+    <ram:ApplicableHeaderTradeAgreement>
+      <ram:BuyerReference>139877</ram:BuyerReference>
+      <ram:SellerTradeParty>
+        <ram:Name>Webware Internet Solutions GmbH</ram:Name>
+        <ram:SpecifiedLegalOrganization>
+          <ram:ID>HRB 15635</ram:ID>
+        </ram:SpecifiedLegalOrganization>
+        <ram:DefinedTradeContact>
+          <ram:PersonName>John Doe</ram:PersonName>
+          <ram:TelephoneUniversalCommunication>
+            <ram:CompleteNumber>+49(0)561-560123456</ram:CompleteNumber>
+          </ram:TelephoneUniversalCommunication>
+          <ram:EmailURIUniversalCommunication>
+            <ram:URIID>johndoe@webware24.de</ram:URIID>
+          </ram:EmailURIUniversalCommunication>
+        </ram:DefinedTradeContact>
+        <ram:PostalTradeAddress>
+          <ram:PostcodeCode>34130</ram:PostcodeCode>
+          <ram:LineOne>Teichstr. 14-16</ram:LineOne>
+          <ram:CityName>Kassel</ram:CityName>
+          <ram:CountryID>DE</ram:CountryID>
+        </ram:PostalTradeAddress>
+        <ram:URIUniversalCommunication>
+          <ram:URIID schemeID="9930">DE279247134</ram:URIID>
+        </ram:URIUniversalCommunication>
+        <ram:SpecifiedTaxRegistration>
+          <ram:ID schemeID="FC">262/481/0918</ram:ID>
+        </ram:SpecifiedTaxRegistration>
+        <ram:SpecifiedTaxRegistration>
+          <ram:ID schemeID="VA">DE279247134</ram:ID>
+        </ram:SpecifiedTaxRegistration>
+      </ram:SellerTradeParty>
+      <ram:BuyerTradeParty>
+        <ram:Name>Agoratech</ram:Name>
+        <ram:PostalTradeAddress>
+          <ram:PostcodeCode>34130</ram:PostcodeCode>
+          <ram:LineOne>Teichstr. 14-16</ram:LineOne>
+          <ram:CityName>Kassel</ram:CityName>
+          <ram:CountryID>DE</ram:CountryID>
+        </ram:PostalTradeAddress>
+        <ram:URIUniversalCommunication>
+          <ram:URIID schemeID="9930">DE319642369</ram:URIID>
+        </ram:URIUniversalCommunication>
+      </ram:BuyerTradeParty>
+    </ram:ApplicableHeaderTradeAgreement>
+    <ram:ApplicableHeaderTradeDelivery>
+      <ram:ActualDeliverySupplyChainEvent>
+        <ram:OccurrenceDateTime>
+          <udt:DateTimeString format="102">20211101</udt:DateTimeString>
+        </ram:OccurrenceDateTime>
+      </ram:ActualDeliverySupplyChainEvent>
+    </ram:ApplicableHeaderTradeDelivery>
+    <ram:ApplicableHeaderTradeSettlement>
+      <ram:InvoiceCurrencyCode>EUR</ram:InvoiceCurrencyCode>
+      <ram:SpecifiedTradeSettlementPaymentMeans>
+        <ram:TypeCode>42</ram:TypeCode>
+        <ram:PayeePartyCreditorFinancialAccount>
+          <ram:IBANID/>
+        </ram:PayeePartyCreditorFinancialAccount>
+        <ram:PayeeSpecifiedCreditorFinancialInstitution>
+          <ram:BICID/>
+        </ram:PayeeSpecifiedCreditorFinancialInstitution>
+      </ram:SpecifiedTradeSettlementPaymentMeans>
+      <ram:ApplicableTradeTax>
+        <ram:CalculatedAmount>228</ram:CalculatedAmount>
+        <ram:TypeCode>VAT</ram:TypeCode>
+        <ram:BasisAmount>1200</ram:BasisAmount>
+        <ram:CategoryCode>S</ram:CategoryCode>
+        <ram:RateApplicablePercent>19.00</ram:RateApplicablePercent>
+      </ram:ApplicableTradeTax>
+      <ram:SpecifiedTradeSettlementHeaderMonetarySummation>
+        <ram:LineTotalAmount>1200</ram:LineTotalAmount>
+        <ram:ChargeTotalAmount>0</ram:ChargeTotalAmount>
+        <ram:AllowanceTotalAmount>0</ram:AllowanceTotalAmount>
+        <ram:TaxBasisTotalAmount>1200.00</ram:TaxBasisTotalAmount>
+        <ram:TaxTotalAmount currencyID="EUR">228.00</ram:TaxTotalAmount>
+        <ram:GrandTotalAmount>1428.00</ram:GrandTotalAmount>
+        <ram:TotalPrepaidAmount>0.00</ram:TotalPrepaidAmount>
+        <ram:DuePayableAmount>1428.00</ram:DuePayableAmount>
+      </ram:SpecifiedTradeSettlementHeaderMonetarySummation>
+    </ram:ApplicableHeaderTradeSettlement>
+  </rsm:SupplyChainTradeTransaction>
+</rsm:CrossIndustryInvoice>

DocumentOperator.Tests/Unit/Application/CheckPdfAttachments/CheckPdfAttachmentsQueryHandlerTests.cs

@@ -0,0 +1,122 @@
+using AutoMapper;
+using DocumentService.Application.CheckPdfAttachments.Queries;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+
+using FluentAssertions;
+using Moq;
+
+namespace DocumentService.Tests.Unit.Application.CheckPdfAttachments;
+
+/// <summary>
+/// Unit tests for CheckPdfAttachmentsQueryHandler.
+/// Tests handler logic with mocked dependencies (IPdfProcessor, IMapper).
+/// </summary>
+public class CheckPdfAttachmentsQueryHandlerTests
+{
+    private readonly Mock<IPdfProcessor> _mockPdfProcessor;
+    private readonly Mock<IMapper> _mockMapper;
+    private readonly CheckPdfAttachmentsQueryHandler _sut;
+
+    public CheckPdfAttachmentsQueryHandlerTests()
+    {
+        _mockPdfProcessor = new Mock<IPdfProcessor>();
+        _mockMapper = new Mock<IMapper>();
+        _sut = new CheckPdfAttachmentsQueryHandler(_mockPdfProcessor.Object, _mockMapper.Object);
+    }
+
+    [Fact]
+    public async Task Handle_WithPdfBytes_CallsProcessorAndMapper()
+    {
+        // Arrange
+        byte[] pdfBytes = "fake-pdf-content"u8.ToArray();
+        var query = new CheckPdfAttachmentsQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        var domainResult = new AttachmentInfo(
+            hasAttachments: true,
+            attachmentCount: 2,
+            attachments:
+            [
+                new("invoice.xml", "text/xml", 1024),
+                new("metadata.json", "application/json", 512)
+            ]
+        );
+
+        var expectedDto = new AttachmentCheckResult
+        {
+            HasAttachments = true,
+            AttachmentCount = 2,
+            Attachments =
+            [
+                new() { FileName = "invoice.xml", MimeType = "text/xml", Size = 1024 },
+                new() { FileName = "metadata.json", MimeType = "application/json", Size = 512 }
+            ]
+        };
+
+        _mockPdfProcessor.Setup(p => p.CheckAttachmentsAsync(It.IsAny<Stream>())).ReturnsAsync(domainResult);
+        _mockMapper.Setup(m => m.Map<AttachmentCheckResult>(domainResult)).Returns(expectedDto);
+
+        // Act
+        var result = await _sut.Handle(query, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Should().BeEquivalentTo(expectedDto);
+
+        _mockPdfProcessor.Verify(p => p.CheckAttachmentsAsync(It.IsAny<Stream>()), Times.Once);
+        _mockMapper.Verify(m => m.Map<AttachmentCheckResult>(domainResult), Times.Once);
+    }
+
+    [Fact]
+    public async Task Handle_WithBase64Pdf_DecodesAndCallsProcessor()
+    {
+        // Arrange
+        byte[] pdfBytes = "fake-pdf-content"u8.ToArray();
+        var query = new CheckPdfAttachmentsQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        var domainResult = new AttachmentInfo(false, 0, []);
+        var expectedDto = new AttachmentCheckResult { HasAttachments = false, AttachmentCount = 0, Attachments = [] };
+
+        _mockPdfProcessor.Setup(p => p.CheckAttachmentsAsync(It.IsAny<Stream>())).ReturnsAsync(domainResult);
+        _mockMapper.Setup(m => m.Map<AttachmentCheckResult>(domainResult)).Returns(expectedDto);
+
+        // Act
+        var result = await _sut.Handle(query, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.HasAttachments.Should().BeFalse();
+        result.AttachmentCount.Should().Be(0);
+
+        _mockPdfProcessor.Verify(p => p.CheckAttachmentsAsync(It.IsAny<Stream>()), Times.Once);
+    }
+
+    [Fact]
+    public async Task Handle_WithEmptyAttachments_ReturnsEmptyList()
+    {
+        // Arrange
+        byte[] pdfBytes = "fake-pdf-content"u8.ToArray();
+        var query = new CheckPdfAttachmentsQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        var domainResult = new AttachmentInfo(false, 0, []);
+        var expectedDto = new AttachmentCheckResult
+        {
+            HasAttachments = false,
+            AttachmentCount = 0,
+            Attachments = []
+        };
+
+        _mockPdfProcessor.Setup(p => p.CheckAttachmentsAsync(It.IsAny<Stream>())).ReturnsAsync(domainResult);
+        _mockMapper.Setup(m => m.Map<AttachmentCheckResult>(domainResult)).Returns(expectedDto);
+
+        // Act
+        var result = await _sut.Handle(query, CancellationToken.None);
+
+        // Assert
+        result.HasAttachments.Should().BeFalse();
+        result.AttachmentCount.Should().Be(0);
+        result.Attachments.Should().BeEmpty();
+    }
+}
+
+

DocumentOperator.Tests/Unit/Application/Features/ValidatePdf/ValidatePdfHandlerTests.cs

@@ -1,14 +1,13 @@
 using AutoMapper;
-using DocumentOperator.Application.Common.DTOs;
-using DocumentOperator.Application.Common.Interfaces;
-using DocumentOperator.Application.ValidatePdf.Queries;
-using DocumentOperator.Domain.Common.Exceptions;
-using DocumentOperator.Domain.Models.ValueObjects;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Application.ValidatePdf.Queries;
+using DocumentService.Domain.Common.Exceptions;
 using FluentAssertions;
 using Moq;
 using Xunit;
 
-namespace DocumentOperator.Tests.Unit.Application.Features.ValidatePdf;
+namespace DocumentService.Tests.Unit.Application.Features.ValidatePdf;
 
 public class ValidatePdfHandlerTests
 {
@@ -27,8 +26,8 @@ public class ValidatePdfHandlerTests
     public async Task Handle_ValidPdf_ReturnsPdfMetadata()
     {
         // Arrange
-        var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
-        var query = new ValidatePdfQuery { PdfBytes = pdfBytes };
+        var pdfBytes = "%PDF"u8.ToArray(); // "%PDF"
+        var query = new ValidatePdfQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         var domainMetadata = new PdfMetadata(
             pageCount: 5,
@@ -48,7 +47,7 @@ public class ValidatePdfHandlerTests
         );
 
         _mockPdfProcessor
-            .Setup(x => x.ValidateAsync(It.IsAny<byte[]>()))
+            .Setup(x => x.ValidateAsync(It.IsAny<Stream>()))
             .ReturnsAsync(domainMetadata);
 
         _mockMapper
@@ -66,7 +65,7 @@ public class ValidatePdfHandlerTests
         result.HasAttachments.Should().BeFalse();
         result.AttachmentCount.Should().Be(0);
 
-        _mockPdfProcessor.Verify(x => x.ValidateAsync(It.IsAny<byte[]>()), Times.Once);
+        _mockPdfProcessor.Verify(x => x.ValidateAsync(It.IsAny<Stream>()), Times.Once);
         _mockMapper.Verify(x => x.Map<PdfValidationResult>(domainMetadata), Times.Once);
     }
 
@@ -74,19 +73,19 @@ public class ValidatePdfHandlerTests
     public async Task Handle_PdfProcessorThrowsException_PropagatesException()
     {
         // Arrange
-        var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
-        var query = new ValidatePdfQuery { PdfBytes = pdfBytes };
+        var pdfBytes = "%PDF"u8.ToArray(); // "%PDF"
+        var query = new ValidatePdfQuery { PdfStream = new MemoryStream(pdfBytes) };
 
         _mockPdfProcessor
-            .Setup(x => x.ValidateAsync(It.IsAny<byte[]>()))
-            .ThrowsAsync(new PdfProcessingException("Invalid PDF format"));
+            .Setup(x => x.ValidateAsync(It.IsAny<Stream>()))
+            .ThrowsAsync(new BadRequestException("Invalid PDF format"));
 
         // Act & Assert
-        var exception = await Assert.ThrowsAsync<PdfProcessingException>(
+        var exception = await Assert.ThrowsAsync<BadRequestException>(
             () => _handler.Handle(query, CancellationToken.None)
         );
 
         exception.Message.Should().Be("Invalid PDF format");
-        _mockPdfProcessor.Verify(x => x.ValidateAsync(It.IsAny<byte[]>()), Times.Once);
+        _mockPdfProcessor.Verify(x => x.ValidateAsync(It.IsAny<Stream>()), Times.Once);
     }
 }

DocumentOperator.Tests/Unit/Application/Features/ValidatePdfA/ValidatePdfAQueryHandlerTests.cs

@@ -0,0 +1,214 @@
+using AutoMapper;
+using DocumentService.Application.Common.DTOs;
+using DocumentService.Application.Common.Interfaces;
+using DocumentService.Application.ValidatePdfA.Queries;
+using DocumentService.Domain.Common.Exceptions;
+
+using FluentAssertions;
+using Moq;
+using Xunit;
+
+namespace DocumentService.Tests.Unit.Application.Features.ValidatePdfA;
+
+public class ValidatePdfAQueryHandlerTests
+{
+    private readonly Mock<IPdfProcessor> _mockPdfProcessor;
+    private readonly Mock<IMapper> _mockMapper;
+    private readonly ValidatePdfAQueryHandler _handler;
+
+    public ValidatePdfAQueryHandlerTests()
+    {
+        _mockPdfProcessor = new Mock<IPdfProcessor>();
+        _mockMapper = new Mock<IMapper>();
+        _handler = new ValidatePdfAQueryHandler(_mockPdfProcessor.Object, _mockMapper.Object);
+    }
+
+    [Fact]
+    public async Task Handle_ValidPdfA_ReturnsPdfAMetadata()
+    {
+        // Arrange
+        var pdfBytes = "%PDF"u8.ToArray(); // "%PDF"
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        var domainMetadata = new PdfAMetadata(
+            isValid: true,
+            pdfVersion: "1.7",
+            pageCount: 3,
+            fileSizeBytes: 2048,
+            encrypted: false,
+            pdfaVersion: "PDF/A-3b",
+            pdfaCompliant: true,
+            errors: [],
+            warnings: []
+        );
+
+        var expectedDto = new PdfAValidationResult
+        {
+            IsValid = true,
+            PdfVersion = "1.7",
+            PageCount = 3,
+            FileSize = 2048,
+            Encrypted = false,
+            PdfAVersion = "PDF/A-3b",
+            PdfACompliant = true,
+            Errors = new List<string>(),
+            Warnings = new List<string>()
+        };
+
+        _mockPdfProcessor
+            .Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))
+            .ReturnsAsync(domainMetadata);
+
+        _mockMapper
+            .Setup(x => x.Map<PdfAValidationResult>(domainMetadata))
+            .Returns(expectedDto);
+
+        // Act
+        var result = await _handler.Handle(query, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.IsValid.Should().BeTrue();
+        result.PageCount.Should().Be(3);
+        result.PdfVersion.Should().Be("1.7");
+        result.PdfAVersion.Should().Be("PDF/A-3b");
+        result.PdfACompliant.Should().BeTrue();
+        result.Encrypted.Should().BeFalse();
+        result.Errors.Should().BeEmpty();
+        result.Warnings.Should().BeEmpty();
+
+        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
+        _mockMapper.Verify(x => x.Map<PdfAValidationResult>(domainMetadata), Times.Once);
+    }
+
+    [Fact]
+    public async Task Handle_NonCompliantPdfA_ReturnsErrorsAndWarnings()
+    {
+        // Arrange
+        var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        var errors = new List<string> { "Missing XMP metadata", "Invalid color space" };
+        var warnings = new List<string> { "Embedded font not subset" };
+
+        var domainMetadata = new PdfAMetadata(
+            isValid: false,
+            pdfVersion: "1.4",
+            pageCount: 2,
+            fileSizeBytes: 1024,
+            encrypted: false,
+            pdfaVersion: null,
+            pdfaCompliant: false,
+            errors: errors,
+            warnings: warnings
+        );
+
+        var expectedDto = new PdfAValidationResult
+        {
+            IsValid = false,
+            PdfVersion = "1.4",
+            PageCount = 2,
+            FileSize = 1024,
+            Encrypted = false,
+            PdfAVersion = null,
+            PdfACompliant = false,
+            Errors = errors,
+            Warnings = warnings
+        };
+
+        _mockPdfProcessor
+            .Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))
+            .ReturnsAsync(domainMetadata);
+
+        _mockMapper
+            .Setup(x => x.Map<PdfAValidationResult>(domainMetadata))
+            .Returns(expectedDto);
+
+        // Act
+        var result = await _handler.Handle(query, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.IsValid.Should().BeFalse();
+        result.PdfACompliant.Should().BeFalse();
+        result.PdfAVersion.Should().BeNull();
+        result.Errors.Should().HaveCount(2);
+        result.Errors.Should().Contain("Missing XMP metadata");
+        result.Warnings.Should().HaveCount(1);
+
+        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
+    }
+
+    [Fact]
+    public async Task Handle_EncryptedPdf_ReturnsEncryptedFlag()
+    {
+        // Arrange
+        var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        var domainMetadata = new PdfAMetadata(
+            isValid: true,
+            pdfVersion: "1.7",
+            pageCount: 1,
+            fileSizeBytes: 512,
+            encrypted: true,
+            pdfaVersion: null,
+            pdfaCompliant: false,
+            errors: new List<string> { "Encrypted PDFs cannot be PDF/A compliant" },
+            warnings: new List<string>()
+        );
+
+        var expectedDto = new PdfAValidationResult
+        {
+            IsValid = true,
+            PdfVersion = "1.7",
+            PageCount = 1,
+            FileSize = 512,
+            Encrypted = true,
+            PdfAVersion = null,
+            PdfACompliant = false,
+            Errors = new List<string> { "Encrypted PDFs cannot be PDF/A compliant" },
+            Warnings = new List<string>()
+        };
+
+        _mockPdfProcessor
+            .Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))
+            .ReturnsAsync(domainMetadata);
+
+        _mockMapper
+            .Setup(x => x.Map<PdfAValidationResult>(domainMetadata))
+            .Returns(expectedDto);
+
+        // Act
+        var result = await _handler.Handle(query, CancellationToken.None);
+
+        // Assert
+        result.Should().NotBeNull();
+        result.Encrypted.Should().BeTrue();
+        result.PdfACompliant.Should().BeFalse();
+        result.Errors.Should().Contain("Encrypted PDFs cannot be PDF/A compliant");
+
+        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
+    }
+
+    [Fact]
+    public async Task Handle_PdfProcessorThrowsException_PropagatesException()
+    {
+        // Arrange
+        var pdfBytes = new byte[] { 0x25, 0x50, 0x44, 0x46 }; // "%PDF"
+        var query = new ValidatePdfAQuery { PdfStream = new MemoryStream(pdfBytes) };
+
+        _mockPdfProcessor
+            .Setup(x => x.ValidatePdfAAsync(It.IsAny<Stream>()))
+            .ThrowsAsync(new BadRequestException("Invalid PDF format"));
+
+        // Act & Assert
+        var exception = await Assert.ThrowsAsync<BadRequestException>(
+            () => _handler.Handle(query, CancellationToken.None)
+        );
+
+        exception.Message.Should().Be("Invalid PDF format");
+        _mockPdfProcessor.Verify(x => x.ValidatePdfAAsync(It.IsAny<Stream>()), Times.Once);
+    }
+}
+