generating-rbs

name	generating-rbs
description	Generates RBS type signatures from Ruby source files. Triggers when creating type definitions, adding types to Ruby code, or generating .rbs files for classes/modules without existing RBS signatures.

RBS Generate Skill

Generate pure RBS signatures for Ruby source files from scratch. Does not handle RBS-inline signatures or updates for existing signatures.

Instructions

When generating RBS signatures from scratch, always follow these steps.

Copy this checklist and track your progress:

RBS Generation Progress:
- [ ] Step 1: Analyze the Ruby source
- [ ] Step 2: Generate RBS signatures
- [ ] Step 3: Eliminate `untyped` types in generated signatures
- [ ] Step 4: Review and refine RBS signatures
- [ ] Step 5: Validate shape of RBS signatures
- [ ] Step 6: Ensure type safety (only if steep is configured)

Rules

There are several rules that you MUST follow while performing this skill:

• You MUST not run Ruby code of the project.
• You MUST not use untyped. Infer the proper type instead.
• You MUST ask the user to provide more details if something is not clear.
• You MUST prepend any command with bundle exec if the project has Gemfile.

1. Analyze the Ruby Source

Always perform this step.

Read and understand the Ruby source file:

• Identify all classes, modules, methods, constants and instance variables.
• Note inheritance, module inclusion and definitions based on metaprogramming.
• Note visibility modifiers - public, private, protected.
• Note type parameters for generic classes.

2. Generate RBS Signatures

Always perform this step.

• Create necessary .rbs files for the target Ruby file.
• Place generated RBS files in sig/ directory mirroring Ruby source structure.
• You need to strongly follow RBS syntax conventions to describe types for all declarations
  • See syntax.md for the full list of RBS types. Double-check it in tricky cases.
• Take inspiration from RBS signature examples
  • See rbs_by_example.md for short list of RBS signatures examples
  • See core for RBS signatures of Ruby core library
  • See stdlib for RBS signatures of Ruby standard library
  • Pay extra attention to Data and Struct types. See data_and_struct.md for handling guide
  • See gem_rbs_collection for RBS signature examples of different Ruby libraries. This link contains only RBS files, Ruby sources are not included.

3. Eliminate untyped types in generated signatures

Always perform this step.

• Go through all generated signatures and replace untyped with the proper type.
• Use assumptions and calls examples in Ruby code and tests to infer the proper type.
• If you cannot infer the proper type, leave it as untyped.
  • It is a last resort, use it only when there is no other option.

4. Review and refine RBS signatures

Always perform this step.

• Take a look at the generated signatures and make sure they are correct, coherent and complete.
• Try to get rid of any unnecessary untyped types.
• If you find any errors, please fix them and repeat the process until there are no errors.

5. Validate shape of RBS signatures

Always perform this step.

• Run rbs validate to verify that existing and new .rbs files are internally consistent. It will check syntax, name resolution, inheritance, method overloading, type variables, etc.
• Fix any errors reported by rbs validate and repeat the process until there are no errors.

6. Ensure type safety of RBS signatures

Perform this step ONLY if the project Gemfile includes steep gem AND the project has Steepfile.

• Run steep check to verify that generated RBS signatures are type safe.
• Fix any errors reported by steep check and repeat the process until there are no errors.
  • Do not modify Steepfile in an attempt to fix errors.
• Roll back to step 4 if you fixed any errors reported by steep check.

References

• syntax.md - The full list of RBS types and syntax
• rbs_by_example.md - Short list of RBS signatures examples
• core - RBS signatures of Ruby core library
• stdlib - RBS signatures of Ruby standard library
• data_and_struct.md - Explanation on Data and Struct types handling