In this presentation at RubyKaigi 2025, Soutaro Matsumoto discusses the documentation feature integrated within the Steep tool, which is built for Ruby's type checking via the Ruby type signature (RBS). This feature introduces an innovative approach to how documentation is accessed and interacted with in Ruby code, enhancing developers' productivity and understanding of API components with real-time support.

Key points covered include:
- Updates on RBS and Steep: The latest updates include improvements in RBS 3.9 and Steep 1.0, which allow for better handling of generic types and improved type checking performance, with features like ignoring certain types of errors.

• Documentation Features in Steep: The Steep tool provides integrated documentation visibility, which appears as hover text within the development environment. This means that users can access class and method documentation directly from their code editor, enhancing the coding experience.

• Real-time Documentation Interaction: When writing Ruby code, developers can access documentation through hover actions, method completion suggestions, and signature help features. These features are derived from comments added to RBS files, formatted in Markdown for clarity and ease of use.

• Internal Documentation Structure: Matsumoto explains the internal API structure that supports this documentation feature, noting how RBS files interact with the Language Server Protocol (LSP). This differs from traditional tools like RDoc or YARD that generate static documentation files. Instead, Steep dynamically generates documentation on the fly based on user interactions.

• Challenges with Overloaded Methods: A significant challenge discussed is identifying and managing overloaded methods within RBS. The current identifier system poses complications, and the presentation proposes using method signatures combined with identifiers to improve clarity and usability.

• Future Goals: Matsumoto expresses intentions to refine this documentation API further, allowing greater integration with other Ruby documentation tools. The goal is to create a robust index system that can store various documentation types effectively.

In conclusion, the implementation of the documentation feature within Steep marks a significant evolution in Ruby programming, promising to enhance the way developers interact with documentation directly from their coding environments. The prospect of collaborative API across different tools in the Ruby ecosystem invites ongoing development and validation of these approaches.