Generating Sorbet Inline

---
name: generating-sorbet-inline
description: Generates Sorbet inline type signatures using sig blocks directly in Ruby source files. Triggers when adding Sorbet types, annotating Ruby methods with sig syntax, or generating type signatures for Sorbet-typed projects.
---

# Sorbet Inline Generation Skill

Generate Sorbet type signatures using `sig {}` blocks directly in Ruby source files. Sorbet signatures are valid Ruby code that enable both static and runtime type checking.

# Instructions

When generating Sorbet inline signatures, always follow these steps.

Copy this checklist and track your progress:

```
Sorbet Inline Generation Progress:
- [ ] Step 1: Analyze the Ruby source
- [ ] Step 2: Add Sorbet signatures
- [ ] Step 3: Eliminate `T.untyped` in signatures
- [ ] Step 4: Review and refine signatures
- [ ] Step 5: Validate signatures with Sorbet
```

## Rules

- You MUST NOT run Ruby code of the project.
- You MUST NOT use `T.untyped`. Infer the proper type instead.
- You MUST NOT use `T.unsafe` - it bypasses type checking entirely.
- You MUST NOT use `T.cast` - it forces types without verification.
- 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.
- You MUST use `sig { }` block syntax for method signatures.
- You MUST add `extend T::Sig` to classes/modules before using `sig`.
- You MUST focus on method signatures only. Skip local variables, intermediate expressions, and other non-method annotations.
- You MUST NOT use or generate `.rbi` files. This skill is for inline signatures only.
- You MUST preserve the existing `# typed:` sigil level if one exists. Do not upgrade or change strictness without explicit user consent.

## 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 existing `# typed:` sigil level at the top of the file.
- Note type parameters for generic classes.

## 2. Add Sorbet Signatures

Always perform this step.

1. First, check if the file already has a `# typed:` sigil at the top:
    - **If sigil exists**: Preserve the existing level. Do not change it without user consent.
    - **If no sigil exists**: Add `# typed: true` as a sensible default (allows gradual typing).

    Sigil levels (least to most strict): `ignore` < `false` < `true` < `strict` < `strong`

2. Add `extend T::Sig` to the class/module:
    ```ruby
    class MyClass
      extend T::Sig
    end
    ```

3. Then add type signatures using `sig {}` blocks:

**Example - Before:**
```ruby
class User
  attr_reader :name, :age

  def initialize(name, age)
    @name = name
    @age = age
  end

  def greet(greeting)
    "#{greeting}, #{@name}!"
  end
end
```

**Example - After:**
```ruby
# typed: true

class User
  extend T::Sig

  sig { returns(String) }
  attr_reader :name

  sig { returns(Integer) }
  attr_reader :age

  sig { params(name: String, age: Integer).void }
  def initialize(name, age)
    @name = name
    @age = age
  end

  sig { params(greeting: String).returns(String) }
  def greet(greeting)
    "#{greeting}, #{@name}!"
  end
end
```

- Focus on method and attribute signatures only
- See [syntax.md](reference/syntax.md) for the full Sorbet syntax guide

## 3. Eliminate `T.untyped` in Signatures

Always perform this step.

- Review all signatures and replace `T.untyped` with proper types.
- Use code context, method calls, and tests to infer types.
- Use `T.untyped` only as a last resort when type cannot be determined.

## 4. Review and Refine Signatures

Always perform this step.

- Verify signatures are correct, coherent, and complete.
- Remove unnecessary `T.untyped` types.
- Ensure all methods and attributes have signatures.
- Fix any errors and repeat until signatures are correct.

## 5. Validate Signatures with Sorbet

Always perform this step.

Run Sorbet type checker to validate signatures:

```bash
srb tc
```

Or with bundle:

```bash
bundle exec srb tc
```

This checks:
- Signature syntax correctness
- Type consistency
- Method parameter/return type matching
- Instance variable initialization

Fix any errors reported and repeat until validation passes.

# References

- [syntax.md](reference/syntax.md) - Sorbet signature syntax guide
- [sorbet_examples/](reference/sorbet_examples/STRUCTURE.md) - Real-world Sorbet examples from production gems
- [Sorbet documentation](https://sorbet.org/docs/overview) - Official Sorbet docs