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.brain/02. Requirements/05. Architecture/C4_Component.md

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+# C4 Architecture Document - Level 3: Component Diagram (Landing Page)
+
+Detailed breakdown of the logical components within the **Sales Landing App** and **BFF Service**.
+
+## 1. Frontend Components (Sales Landing App)
+
+### 1.1. Modules
+- **Auth Module**: Login form, Token handling.
+- **Customer Module**: Input form, Camera/Upload Component for OCR.
+- **Product Module**: Product selection interface (Card selection for UVL-IC/UVL-EL).
+- **Illustration Module**: PDF display (PDF Viewer) and download/Submit buttons.
+
+### 1.2. Shared
+- **UI Kit**: Button, Input, Modal (matching the Design System).
+- **API Client**: Axios wrapper for calling the BFF.
+
+## 2. Backend Components (BFF Service)
+
+### 2.1. Controllers
+- **AuthController**: Authentication via Auth API.
+- **OCRController**: Proxies images to the OCR Service.
+- **IllustrationController**: Aggregates data -> Calls PDF Engine -> Returns URL/File.
+- **SubmissionController**: Submits final data to the Core system.
+
+### 2.2. Services
+- **ClientService**: Saves/Retrieves customer information from the Database.
+
+## 3. Component Diagram
+
+```mermaid
+C4Component
+    title Component Diagram - Landing Page System
+
+    Container_Boundary(frontend, "Sales Landing App") {
+        Component(c_auth, "Auth Module", "React", "Login Screen")
+        Component(c_cust, "Customer Module", "React", "Form & OCR Upload")
+        Component(c_pdf, "Illustration Module", "React", "PDF View & Submit")
+    }
+
+    Container_Boundary(backend, "BFF Service") {
+        Component(ctl_ocr, "OCR Controller", "Node.js", "Handle Upload & Proxy")
+        Component(ctl_ill, "Illustration Controller", "Node.js", "Coordinate PDF Gen")
+        Component(svc_client, "Client Service", "Node.js", "Manage Client Data DB")
+    }
+
+    ContainerDb(db, "PostgreSQL", "Database", "Store Drafts")
+    System_Ext(ocr_ext, "External OCR", "Service")
+    System_Ext(pdf_ext, "External PDF Gen", "Service")
+
+    Rel(c_auth, ctl_ocr, "Authenticated Req")
+    Rel(c_cust, ctl_ocr, "Upload Image")
+    Rel(c_cust, ctl_ill, "Request PDF")
+    
+    Rel(ctl_ocr, ocr_ext, "Proxy")
+    Rel(ctl_ill, pdf_ext, "Proxy")
+    Rel(ctl_ill, svc_client, "Save Info")
+    Rel(svc_client, db, "Persist")
+```
+
+---
+*Authored by: Agent mbl-landing-page-architecture*