# Nexical Ecosystem Documentation > The SaaS Operating System for the AI Era. ## Documentation Map - [Nexical Ecosystem](http://localhost:4321/): The SaaS Operating System for the AI Era. - [Coding Standards](http://localhost:4321/architecture/coding-standards): Strict guidelines for ensuring maintainability and scalability. - [Architectural Overview](http://localhost:4321/architecture/overview): The high-level design of the Nexical Ecosystem. - [Database & Schema](http://localhost:4321/core-api/database): The Additive Schema Architecture. - [Email System](http://localhost:4321/core-api/email): Pluggable email templates and sending logic. - [Event Bus (HookSystem)](http://localhost:4321/core-api/hooks): Decoupling modules with cross-module events and filters. - [Internationalization (i18n)](http://localhost:4321/core-api/i18n): Translations and locale management. - [Registries](http://localhost:4321/core-api/registries): Understanding the dynamic registration patterns. - [Security & Auth](http://localhost:4321/core-api/security): Middleware pipelines, RBAC, and ABAC patterns. - [System Utilities](http://localhost:4321/core-api/utilities): Logger, Config, and other core helpers. - [Theming System](http://localhost:4321/ui/theming): Guide to the styling architecture and component vocabulary. - [How to Add a Database Model](http://localhost:4321/guides/add-model): Step-by-step guide to extending the database schema. - [How to Create an API Endpoint](http://localhost:4321/guides/create-endpoint): Step-by-step guide to building a new API route using the Modular API system. - [How to Create a Widget](http://localhost:4321/guides/create-widget): Step-by-step guide to adding a component to the registry. - [Agent Runtime](http://localhost:4321/module-dev/agent-runtime): Background job processing and autonomous actors. - [Module Anatomy](http://localhost:4321/module-dev/anatomy): detailed guide to the structure of a Nexical module. - [Introduction to Modules](http://localhost:4321/module-dev/introduction): Understanding the ArcNexus Modular Extension System. - [E2E Testing (Playwright)](http://localhost:4321/module-dev/testing-e2e): The Playwright-based End-to-End testing framework. - [Integration Testing](http://localhost:4321/module-dev/testing-integration): The "Black Box API / White Box Data" testing framework. ## Full Documentation For the complete context, access [llms-full.txt](http://localhost:4321/llms-full.txt).