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+# C4 Architecture Documentation System - Landing Page Sales Party
+
+This repository consolidates the system architecture for the **Landing Page for Sales** project, helping the development team grasp the structure from a broad overview down to intricate details.
+
+## Document Index
+
+### [Level 1: System Context](./C4_Context.md)
+- **Description**: The big picture of interactions between the Sales Agent, the Landing Page system, and external partners (OCR, Auth, Core).
+- **Focus**: Identifying system boundaries and integration points.
+
+### [Level 2: Container Diagram](./C4_Container.md)
+- **Description**: Decomposing the system into the Web App (Frontend), BFF (Backend), and Database.
+- **Technologies**: React, Node.js, PostgreSQL.
+
+### [Level 3: Component Diagram](./C4_Component.md)
+- **Description**: The internal structure of the Frontend (Modules) and Backend BFF (Controllers/Services).
+- **Focus**: Processing logic for OCR and illustration generation.
+
+### [Level 4: Code Documentation](./C4_Code.md)
+- **Description**: Detailed data processing flows (Sequence Diagram) and State management on the Frontend.
+- **Focus**: The data synchronization mechanism between the input form and the PDF Viewer.
+
+---
+*Last updated by: Agent mbl-landing-page-architecture*