Here are docs explaining how Gato GraphQL was built.

Service container implementation:

• Building extensible PHP apps with Symfony DI

Explanation of how the codebase is split into granular packages, to enable CMS-agnosticism:

1. Abstracting WordPress Code To Reuse With Other CMSs: Concepts (Part 1)
2. Abstracting WordPress Code To Reuse With Other CMSs: Implementation (Part 2)

Description of how the plugin is scoped:

• Gato GraphQL is now scoped, thanks to PHP-Scoper!

Gato GraphQL is powered by the CMS-agnostic GraphQL server GraphQL by PoP.

Technical information on how the GraphQL server works:

• GraphQL by PoP documentation.

Description of how a GraphQL server using server-side components works:

• Implementing a GraphQL server with components in PHP

These articles explain the concepts, design and implementation of GraphQL by PoP:

1. Designing a GraphQL server for optimal performance
2. Simplifying the GraphQL data model
3. Schema-first vs code-first development in GraphQL
4. Speeding-up changes to the GraphQL schema
5. Versioning fields in GraphQL
6. GraphQL directives are underrated
7. Treating GraphQL directives as middleware
8. Creating an @export GraphQL directive
9. Adding directives to the schema in code-first GraphQL servers
10. Coding a GraphQL server in JavaScript vs. WordPress
11. Supporting opt-in nested mutations in GraphQL
12. HTTP caching in GraphQL

These articles explain the integration with Gutenberg (the WordPress editor).

1. Adding a Custom Welcome Guide to the WordPress Block Editor
2. Using Markdown and Localization in the WordPress Block Editor