ESPHome Designer is a Home Assistant custom component that provides a visual drag-and-drop editor for designing display layouts on ESP32/ESP8266 devices running ESPHome. It supports multiple rendering protocols including native ESPHome C++ lambdas, LVGL, OpenEPaperLink (OEPL), and OpenDisplay (ODP). The editor features a canvas with zoom/pan, snap-to-grid, drag-and-drop, lasso selection, and a property panel for configuring widget attributes. Widgets are organized as plugins, each providing render, export, and lifecycle hooks for all supported output formats. The system can generate complete ESPHome YAML configurations including hardware definitions, sensor registrations, font loading, and display lambdas. The architecture is split between a Python backend (Home Assistant integration) and a JavaScript frontend (Vite-built SPA). The backend provides REST APIs for layout CRUD, entity history proxying, image/RSS proxying, hardware profile management, and PNG rendering. The frontend manages state via an AppState singleton with undo/redo, communicates with the backend through a bridge, and supports offline YAML parsing. An AI integration allows generating layouts from natural language prompts using multiple providers (Gemini, OpenAI, OpenRouter). The codebase demonstrates strong engineering practices with a plugin-based architecture, adapter pattern for multi-format export, schema-driven property panels, and extensive test coverage (200+ Vitest tests plus Python tests). It is actively maintained with CI/CD pipelines, quality gates, and regular releases. While the widget plugin surface is large and some legacy modules coexist with newer code, the overall design is modular and extensible.