diff --git a/EnvelopeGenerator.sln b/EnvelopeGenerator.sln
index 45a720f9..1158a000 100644
--- a/EnvelopeGenerator.sln
+++ b/EnvelopeGenerator.sln
@@ -22,6 +22,7 @@ EndProject
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{134D4164-B291-4E19-99B9-E4FA3AFAB62C}"
ProjectSection(SolutionItems) = preProject
COPILOT_CONTEXT.md = COPILOT_CONTEXT.md
+ FORM_APPLICATION_CONTEXT.md = FORM_APPLICATION_CONTEXT.md
EndProjectSection
EndProject
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{0CBC2432-A561-4440-89BC-671B66A24146}"
diff --git a/FORM_APPLICATION_CONTEXT.md b/FORM_APPLICATION_CONTEXT.md
new file mode 100644
index 00000000..948290e6
--- /dev/null
+++ b/FORM_APPLICATION_CONTEXT.md
@@ -0,0 +1,788 @@
+# EnvelopeGenerator.Form – VB.NET Desktop Application Context
+
+## Purpose
+**Legacy Windows Forms application** for envelope creation, management, and signature field placement. Built with **DevExpress components** and **GdPicture14** for PDF manipulation. This application is being **migrated to ReceiverUI + API** architecture.
+
+**Primary Libraries:** DevExpress XtraGrid/XtraEditors, GdPicture14, VB.NET (.NET Framework 4.6.2)
+
+---
+
+## Application Architecture
+
+### Projects Structure
+| Project | Purpose |
+|---|---|
+| **EnvelopeGenerator.Form** | Main WinForms UI (VB.NET) |
+| **EnvelopeGenerator.CommonServices** | Shared services/helpers |
+| **EnvelopeGenerator.Service** | Windows Service (legacy) |
+| **EnvelopeGenerator.BBTests** | Tests |
+
+### Key Forms (Pages)
+
+#### 1. **frmMain.vb** - Envelope Overview (Dashboard)
+**Route Equivalent:** `/sender` (EnvelopeSenderPage.razor)
+
+**Purpose:** Main dashboard showing all envelopes with status filtering.
+
+**Key Features:**
+- **Tab-based layout** with 2+2 tabs:
+ - **Tab 0:** Active Envelopes (not sent/partially signed)
+ - **Tab 1:** Completed Envelopes (signed/rejected/deleted)
+ - **Tab 2:** Reports (Admin only)
+ - **Tab 3:** Additional Reports (Admin only)
+
+**Envelope Status Colors:**
+| Status | Color | Hex Code | Description |
+|---|---|---|---|
+| `EnvelopePartlySigned` | Green | `#81C784` (GREEN_300) | At least one receiver signed |
+| `EnvelopeQueued` / `EnvelopeSent` | Orange | `#FFB74D` (ORANGE_300) | Sent to receivers, awaiting signatures |
+| `EnvelopeCompletelySigned` | Green | `#81C784` (GREEN_300) | All receivers signed |
+| `EnvelopeDeleted` / `EnvelopeWithdrawn` / `EnvelopeRejected` | Red | `#E57373` (RED_300) | Envelope cancelled/rejected |
+
+**Receiver Status Colors (in detail grids):**
+| Status | Color | Hex Code |
+|---|---|---|
+| `Signed` | Green | `#81C784` (GREEN_300) |
+| `Not Signed` | Red | `#E57373` (RED_300) |
+
+**Grid Layouts:**
+
+1. **GridEnvelopes** (Active):
+ - Columns: ID, Title, Status, Created Date, Creator
+ - **Master-Detail:** Expands to show:
+ - **ViewReceivers:** Receiver list with status colors
+ - **ViewHistory:** Envelope history (status changes, emails sent)
+
+2. **GridCompleted** (Completed):
+ - Same structure as GridEnvelopes
+ - **ViewReceiversCompleted** and **ViewHistoryCompleted** detail grids
+
+**Toolbar Actions:**
+| Button | Action | Enabled When |
+|---|---|---|
+| **Create Envelope** | Opens `frmEnvelopeEditor` | Always |
+| **Edit Envelope** | Opens `frmEnvelopeEditor` with selected envelope | Envelope selected & not sent |
+| **Delete Envelope** | Shows `frmRueckruf` (reason dialog) ? deletes | Envelope selected |
+| **Show Document** | Opens PDF in temp folder | Envelope & document selected |
+| **Contact Receiver** | Opens mailto link | Receiver selected |
+| **Resend Invitation** | Resends email to receiver | Receiver selected |
+| **Send Access Code** | Manually sends access code email | Receiver selected & UseAccessCode=true |
+| **Info Mail** | Opens mailto to support team | Receiver selected (for issues) |
+| **2FA Properties** | Shows `frm2Factor_Properties` dialog | Receiver selected & TFA enabled |
+| **Export Report (EB)** | Exports completed envelope result PDF | Completed envelope selected |
+| **Refresh** | Reloads data | Always |
+| **Export to Excel** | Exports current grid to XLSX | Always |
+
+**Auto-Refresh:** Timer refreshes every N seconds (configurable), but **only when `frmEnvelopeEditor` is not open**.
+
+**Persistence:** Grid layouts saved to `{GridViewName}_UserLayout.xml` in user AppData folder.
+
+---
+
+#### 2. **frmEnvelopeEditor.vb** - Envelope Creation/Edit
+**Route Equivalent:** `/sender/envelope/{id}` (future)
+
+**Purpose:** Create or edit envelope details, add documents, manage receivers.
+
+**Workflow:**
+1. **On New Envelope:** Opens `frmEnvelopeMainData` popup **first** (title, type, settings)
+2. **After popup OK:** Main editor loads
+3. **Add Document:** Single PDF file (via Open Dialog or Drag & Drop)
+4. **Add Receivers:** Grid with auto-complete from previous emails
+5. **Edit Fields:** Opens `frmFieldEditor` for signature field placement
+6. **Send Envelope:** Validates and sends invitations
+
+**UI Layout:**
+- **Top Ribbon:** DevExpress ribbon with actions
+- **Left Panel:** Document list (thumbnail + details)
+- **Right Panel:** Receiver list (name, email, access code, phone)
+- **Bottom Bar:** Envelope ID, Creator Email, Info messages
+
+**Ribbon Actions:**
+| Button | Action | Enabled When |
+|---|---|---|
+| **Add File** | Opens file dialog | No document added |
+| **Merge Files** | Opens `frmOrderFiles` to concatenate PDFs | No document added |
+| **Delete File** | Removes document | Document selected |
+| **Show File** | Opens PDF in default viewer | Document selected |
+| **Edit Fields** | Opens `frmFieldEditor` | Document + receivers exist |
+| **Edit Data** | Opens `frmEnvelopeMainData` | Always |
+| **Save** | Saves envelope without validation | Always |
+| **Send Envelope** | Validates & sends invitations | Document + receivers exist |
+| **Cancel** | Closes with save prompt | Always |
+| **Delete Receiver** | Removes receiver from list | Receiver selected |
+
+**Receiver Grid:**
+- **Columns:** Name, Email, Access Code, Phone (if TFA enabled)
+- **Auto-complete:** Email field suggests previous receivers
+- **Validation:** Email format, Phone format (+49... for TFA)
+- **Access Code:** Auto-generated on email entry (if UseAccessCode=true)
+- **Color Assignment:** Each receiver gets a unique color (for signature fields)
+
+**Document Grid:**
+- **Single file only** (currently limited to 1 PDF)
+- **Thumbnail:** Generated via GdPicture14
+- **Page Count:** Displayed
+
+**Drag & Drop:**
+- Drop PDF files directly onto form
+- Only 1 file allowed
+- Visual feedback (red bar if >1 file)
+
+**Validation:**
+- Title required
+- Message required
+- At least 1 document
+- At least 1 receiver
+- Valid email addresses
+- Valid phone numbers (if TFA enabled)
+- Signature fields exist for each receiver (before sending)
+
+---
+
+#### 3. **frmEnvelopeMainData.vb** - Envelope Settings Popup
+**Route Equivalent:** Part of `/sender/envelope/{id}` (inline in ReceiverUI)
+
+**Purpose:** Configure envelope metadata and behavior. **Shown as modal popup** before main editor.
+
+**Fields:**
+
+| Field | Type | Description |
+|---|---|---|
+| **Title** | Text | Envelope title (required) |
+| **Envelope Type** | Dropdown | Template (ContractType, Language, defaults) |
+| **Language** | Dropdown | de/en |
+| **Use Access Code** | Checkbox | Require 6-digit code for signing |
+| **2FA Enabled** | Checkbox | Require SMS verification (forces Access Code ON) |
+| **Certification Type** | Dropdown | Basic / Advanced / Qualified |
+| **Final Email to Creator** | Dropdown | No / OnComplete / OnCompleteOrReject |
+| **Final Email to Receivers** | Dropdown | No / OnComplete / OnCompleteOrReject |
+| **Send Reminder Emails** | Checkbox | Auto-send reminders |
+| **First Reminder Days** | Number | Days before first reminder |
+| **Reminder Interval Days** | Number | Days between reminders |
+| **Expires When Days** | Number | Days until envelope expires |
+| **Expires Warning Days** | Number | Days before expiry to warn |
+
+**Layout:**
+- **Compact mode:** Only Title, Type, Language visible
+- **Expanded mode:** Click "All Options" to show reminder/expiry settings
+
+**Behavior:**
+- **On Type Selection:** Auto-fills all settings from template
+- **On 2FA Enable:** Forces "Use Access Code" ON and disables checkbox
+- **On New Envelope:** Shows before main editor
+- **On Edit Envelope:** Opens as separate dialog, Type field read-only
+
+**Validation:** Title is required (red border via Adorner).
+
+---
+
+#### 4. **frmFieldEditor.vb** - Signature Field Placement
+**Route Equivalent:** `/sender/envelope/{id}/fields` (future, or inline in editor)
+
+**Purpose:** Place signature fields on PDF pages using **GdPicture14** viewer with annotations.
+
+**UI Layout:**
+- **Left:** PDF Viewer (GdViewer) with annotation tools
+- **Right:** Thumbnail navigator (ThumbnailEx2)
+- **Top:** Toolbar with receiver selector and actions
+
+**Toolbar:**
+| Button | Action |
+|---|---|
+| **Receiver Selector** | Popup menu with receiver names (colored circles) |
+| **Add Signature** | Draws new signature annotation |
+| **Delete** | Removes selected annotation |
+| **Save** | Saves signature fields to database |
+
+**Signature Field Details:**
+- **Size:** 1.77" × 1.96" (4.5cm × 5cm) - **FIXED SIZE**
+- **Color:** Matches receiver color (from grid assignment)
+- **Label:** "SIGNATUR" (or localized "Signature")
+- **Position:** Draggable on PDF canvas
+- **Database Format:** Coordinates stored in **INCHES** (GdPicture native)
+
+**Coordinate System:**
+- **Origin:** Top-left corner
+- **Units:** Inches (not points or pixels)
+- **Axes:** X right, Y down
+- **Storage:** Direct INCHES values (no conversion)
+
+**Evidence from Code:**
+```vb
+Private Const SIGNATURE_WIDTH As Single = 1.77 ' inches
+Private Const SIGNATURE_HEIGHT As Single = 1.96 ' inches
+
+Sub LoadAnnotation(pElement As DocReceiverElement, ...)
+ oAnnotation.Left = CSng(pElement.X) ' Direct INCHES assignment
+ oAnnotation.Top = CSng(pElement.Y)
+End Sub
+```
+
+**Multi-Receiver Support:**
+- **Receiver switcher:** Click receiver name in popup menu
+- **Current receiver:** Highlighted in toolbar (name + colored circle)
+- **Other receivers' fields:** Shown semi-transparent (30% opacity), not selectable
+- **Save:** Saves current receiver's fields, switches receiver, reloads all annotations
+
+**Annotation Behavior:**
+- **New annotation:** User clicks "Add Signature" ? draws interactive annotation ? auto-sized to 1.77×1.96
+- **Existing annotation:** Loaded from database, locked size (can move but not resize)
+- **Styling:** Filled rectangle with centered text "SIGNATUR"
+- **Validation:** No resize, no text edit, no rotation
+
+**Unsaved Changes Prompt:**
+- On form close: "There are unsaved changes. Save? Yes/No/Cancel"
+- Yes ? Saves ? Closes
+- No ? Discards ? Closes
+- Cancel ? Stays open
+
+---
+
+#### 5. **frmRueckruf.vb** - Delete Reason Dialog
+**Route Equivalent:** Inline confirmation in ReceiverUI
+
+**Purpose:** Capture reason for envelope deletion/withdrawal.
+
+**Fields:**
+- **Envelope ID** (display only)
+- **Envelope Title** (display only)
+- **Reason** (required text box)
+
+**Buttons:**
+- **OK:** Confirms deletion with reason
+- **Cancel:** Cancels operation
+
+**Global Variables:**
+```vb
+Public CurrentEnvelopID As Long
+Public CurrentEnvelopetitle As String
+Public Shared Continue_Reject As Boolean = False
+Public Shared Reject_reason As String = ""
+```
+
+---
+
+#### 6. **frm2Factor_Properties.vb** - 2FA Management
+**Route Equivalent:** `/admin/2fa/{email}` (future admin panel)
+
+**Purpose:** View/manage 2FA settings for a receiver.
+
+**Fields:**
+- **Email Address** (display only)
+- **TOTP Secret Key** (display only)
+- **Registration Deadline** (display only)
+
+**Usage:** Admin tool to debug 2FA issues or reset TOTP secrets.
+
+---
+
+#### 7. **frmOrderFiles.vb** - PDF Merge Tool
+**Route Equivalent:** Inline in ReceiverUI (future)
+
+**Purpose:** Select multiple PDFs and merge them into a single document.
+
+**UI:**
+- **File list:** Selected PDFs
+- **Up/Down buttons:** Reorder files
+- **Add/Remove buttons:** Manage list
+
+**Merge Logic:**
+- Uses GdPicture14 `MergeDocuments()`
+- Output: Single PDF in temp folder
+- Auto-loaded as envelope document
+
+---
+
+## Data Models (Controllers)
+
+### EnvelopeListController
+**Purpose:** Load envelope lists for dashboard grids.
+
+**Methods:**
+- `ListEnvelopes()` ? Active envelopes (not completed)
+- `ListCompleted()` ? Completed envelopes (signed/rejected/deleted)
+- `DeleteEnvelope(envelope, reason)` ? Soft delete with reason
+- `GetPieChart()` ? DevExpress ChartControl (not used)
+- `GetEnvelopeReceiverAddresses(userId)` ? List of previous receiver emails (for auto-complete)
+
+---
+
+### EnvelopeEditorController
+**Purpose:** Manage envelope CRUD and document/receiver operations.
+
+**Key Methods:**
+
+| Method | Purpose |
+|---|---|
+| `CreateDocument(filePath)` | Imports PDF, extracts pages/thumbnail, saves to DB |
+| `DeleteDocument(document)` | Removes document from envelope |
+| `SaveReceivers(envelope, receivers)` | Saves/updates receivers with access codes |
+| `DeleteReceiver(receiver)` | Removes receiver (checks if fields exist) |
+| `ElementsExist(receiverId)` | Checks if signature fields exist for receiver |
+| `SaveEnvelope()` | Persists envelope to database |
+| `SendEnvelope()` | Validates, queues emails, sends invitations |
+| `ValidateEnvelopeForSending(errors)` | Checks all receivers have signature fields |
+| `GetLastNameByEmailAdress(email)` | Returns previous name for email (auto-fill) |
+| `GetLastPhoneByEmailAdress(email)` | Returns previous phone for email (auto-fill) |
+| `DeleteEnvelopeFromDisk(envelope)` | Cleans up temp files |
+
+**ActionService Methods:**
+- `ResendReceiver(envelope, receiver)` ? Resends invitation email
+- `ManuallySendAccessCode(envelope, receiver)` ? Sends access code email
+
+---
+
+### FieldEditorController
+**Purpose:** Manage signature field annotations (DocReceiverElement).
+
+**Key Methods:**
+
+| Method | Purpose |
+|---|---|
+| `LoadElements()` | Loads all signature fields from database |
+| `AddOrUpdateElement(annotation, orientation)` | Converts GdPicture annotation ? DocReceiverElement |
+| `SaveElements(receiverId)` | Persists signature fields for receiver |
+| `DeleteElement(element)` | Removes signature field |
+| `GetElement(annotation)` | Finds element by annotation tag |
+| `GetElementInfo(tag)` | Parses annotation tag (receiverId\|page\|guid) |
+
+**Annotation Tag Format:**
+```
+"{receiverId}|{page}|{elementId}"
+Example: "42|1|-1" (receiver 42, page 1, unsaved)
+Example: "42|1|137" (receiver 42, page 1, element ID 137)
+```
+
+**Element Coordinate Conversion:**
+```vb
+' Database stores INCHES directly (GdPicture native)
+Sub AddOrUpdateElement(annotation, orientation)
+ element.X = annotation.Left ' INCHES
+ element.Y = annotation.Top ' INCHES
+ element.Width = annotation.Width ' INCHES
+ element.Height = annotation.Height ' INCHES
+ element.Page = currentPage
+End Sub
+```
+
+---
+
+## Migration to ReceiverUI + API
+
+### Mapping Table
+
+| Form Feature | ReceiverUI Equivalent | Status |
+|---|---|---|
+| **frmMain** (Envelope list) | `/sender` (EnvelopeSenderPage.razor) | ? Exists |
+| Tab 0: Active Envelopes | `/sender` default view | ? Grid with filters |
+| Tab 1: Completed Envelopes | `/sender` with status filter | ? Same grid |
+| Status colors (Green/Orange/Red) | CSS classes `.status-signed`, `.status-pending`, etc. | ?? **Needs implementation** |
+| Master-detail grids (Receivers/History) | Expandable rows or modal dialogs | ?? **Needs implementation** |
+| Toolbar: Create Envelope | Button ? `/sender/envelope/new` | ?? **Needs implementation** |
+| Toolbar: Edit Envelope | Button ? `/sender/envelope/{id}` | ?? **Needs implementation** |
+| Toolbar: Delete Envelope | Button ? Shows delete reason modal | ?? **Needs implementation** |
+| Toolbar: Show Document | Downloads PDF | ?? **Needs implementation** |
+| Toolbar: Contact Receiver | `mailto:` link | ?? **Needs implementation** |
+| Toolbar: Resend Invitation | API call ? refresh grid | ?? **Needs implementation** |
+| Toolbar: Export Excel | Download XLSX | ?? **Needs implementation** |
+| Auto-refresh timer | SignalR or polling | ?? **Needs implementation** |
+| Grid layout persistence | LocalStorage | ?? **Needs implementation** |
+| **frmEnvelopeEditor** | `/sender/envelope/{id}` | ? **Not implemented** |
+| ? **frmEnvelopeMainData** popup | Inline form section or stepper | ? **Not implemented** |
+| Document upload (Drag & Drop) | Blazor InputFile with drag zone | ?? **Needs implementation** |
+| Receiver grid (auto-complete) | DevExpress Blazor Grid with lookup | ?? **Needs implementation** |
+| Merge PDFs (frmOrderFiles) | Client-side PDF.js or server-side | ?? **Needs implementation** |
+| **frmFieldEditor** | `/sender/envelope/{id}/fields` or inline | ? **Not implemented** |
+| GdPicture PDF viewer | PDF.js + canvas overlay (like EnvelopeReceiverPage) | ?? **Partial (receiver side only)** |
+| Signature field placement | Drag & drop signature boxes on canvas | ? **Not implemented** |
+| Receiver color coding | CSS variables + signature field borders | ? **Not implemented** |
+| Multi-receiver switcher | Dropdown or tabs | ? **Not implemented** |
+| Thumbnail navigator | PDF.js thumbnail sidebar (like receiver) | ?? **Exists for receiver** |
+| Save signature fields | API POST `/api/Envelope/{id}/Elements` | ? **Not implemented** |
+| **frm2Factor_Properties** | Admin panel `/admin/2fa/{email}` | ? **Not implemented** |
+| **frmRueckruf** (Delete reason) | Modal dialog in EnvelopeSenderPage | ?? **Needs implementation** |
+
+---
+
+## Critical Implementation Notes
+
+### 1. **Coordinate System Consistency**
+**Database (Form App):** INCHES (GdPicture native)
+**ReceiverUI (PDF.js):** Pixels on canvas
+**Conversion Required:**
+```csharp
+// Sender side (placing fields):
+float xInches = canvasPixelX / (canvasWidth / pageWidthInches);
+float yInches = canvasPixelY / (canvasHeight / pageHeightInches);
+
+// Receiver side (displaying fields):
+float canvasX = (xInches / pageWidthInches) * canvasWidth;
+float canvasY = (yInches / pageHeightInches) * canvasHeight;
+```
+
+**A4 Page Dimensions:**
+- Width: 8.27" = 595pt
+- Height: 11.69" = 842pt
+
+---
+
+### 2. **Status Color System**
+Form app uses **DevExpress CustomDrawCell** event for row coloring. ReceiverUI should use:
+
+```css
+/* Envelope status colors */
+.envelope-row.status-partly-signed { background-color: #81C784; } /* GREEN_300 */
+.envelope-row.status-queued,
+.envelope-row.status-sent { background-color: #FFB74D; } /* ORANGE_300 */
+.envelope-row.status-completed { background-color: #81C784; } /* GREEN_300 */
+.envelope-row.status-deleted,
+.envelope-row.status-rejected { background-color: #E57373; } /* RED_300 */
+
+/* Receiver status colors */
+.receiver-row.signed { background-color: #81C784; }
+.receiver-row.unsigned { background-color: #E57373; }
+```
+
+---
+
+### 3. **Master-Detail Grid Pattern**
+Form app uses **nested GridViews** (ViewReceivers, ViewHistory). ReceiverUI options:
+
+**Option A:** DevExpress Blazor Grid with master-detail template
+```razor
+
+
+
+
+
+
+
+
+
+```
+
+**Option B:** Click row ? show modal with receivers/history
+```razor
+
+...
+
+
+
+
+ ...
+
+
+```
+
+---
+
+### 4. **Signature Field Editor Architecture**
+
+**Form App:**
+- GdPicture14 native annotations
+- Fixed size (1.77×1.96 inches)
+- Color-coded per receiver
+- Draggable, non-resizable
+
+**ReceiverUI Equivalent:**
+- PDF.js canvas + HTML overlay (like receiver signature buttons)
+- `
` positioned absolutely
+- Drag & drop with JS (`onmousedown`, `onmousemove`, `onmouseup`)
+- Snap to grid (optional)
+- Store coordinates in INCHES (convert from pixels)
+
+**Example HTML Overlay:**
+```html
+