...It documents the kernel, capsule model, host ABI, bus, and security model in one structured technical book. The project is built with mdBook, making it suitable for browsing, serving, and maintaining as developer documentation. It is intended to act as a stable reference for how Astrid OS components interact and how its core abstractions are defined. The repository also includes tooling that generates reference appendices from the Astrid source tree. These appendices cover areas such as the capability catalog, host ABI error codes, and topic registry, while additional scripts generate cross-chapter navigation aids.