Write Standalone RBS Signatures

You are writing RBS type signatures in standalone .rbs files for the Ruby code at: $ARGUMENTS

Process

1. Load the RBS Skill

First, load the RBS skill to get comprehensive type syntax knowledge:

Use the Skill tool to load: ruby-inline-rbs

Then read the standalone RBS subskill for file format details:

• subskills/rbs-files/SKILL.md

2. Analyze Target

Read the Ruby file(s) specified by the user:

• Understand class/module structure
• Note method signatures, parameters, return patterns
• Identify instance variables
• Look for DSL usage (attr_*, delegate, etc.)

3. Find Tests

Search for related test files:

Glob for: test/**/*{target_name}*_test.rb, spec/**/*{target_name}*_spec.rb

Read tests to understand:

• Expected method behavior
• Edge cases (nil returns, exceptions)
• Type expectations from assertions

4. Use Type Tracer (If Tests Exist)

If tests exist, consider running the type tracer:

# First locate type_tracer.rb in plugin directory using find
ruby <TRACER_SCRIPT> -c 'TargetClass' -f json path/to/test.rb

Review tracer output to inform type decisions.

5. Generate Scaffold (Optional)

For complex files, generate an initial scaffold:

bundle exec rbs prototype rb lib/target.rb

6. Write RBS

Create the .rbs file in sig/ mirroring the lib/ structure:

lib/my_app/user.rb → sig/my_app/user.rbs

Follow these principles:

• Start with public API methods
• Use appropriate types (avoid untyped where possible)
• Consider generics for container classes
• Use interfaces for duck typing
• Add optional markers (?) for nilable returns

7. Validate

Run validation to check your work:

bundle exec rbs validate
bundle exec steep check lib/target.rb

Fix any errors before completing.

Output

Create/update the following:

1. sig/**/*.rbs - Type signature files
2. Report what was typed and any decisions made

Tips

• Match RBS file structure to Ruby file structure
• Don't type private implementation details unless needed
• Use untyped for genuinely dynamic/complex code
• Check gem_rbs_collection for third-party type definitions
• Reference references/type-syntax.md for syntax questions