Other projects that depend on sinclair need a reference file they can drop into their own .github/ folder so GitHub Copilot understands how to use the gem correctly.

Changes

• Adds .github/sinclair-usage.md — a self-contained usage guide covering every public-facing feature of the gem with annotated code examples:
  • Sinclair builder: stand-alone, block DSL, string/block/call method definitions, result caching, and subclassing for custom builders
  • Sinclair::Configurable / Sinclair::Config: read-only config with defaults, reset, as_options, and custom config classes
  • Sinclair::Options: validated keyword-argument objects with defaults and InvalidOptions on unknown keys
  • Sinclair::EnvSettable: ENV vars as class methods with prefix and type casting
  • Sinclair::Comparable: attribute-based == via comparable_by
  • Sinclair::Model: quick plain-Ruby models with initialize_with, writter:, and comparable: options
  • Sinclair::Caster: named and class-keyed type-casting registry
  • Sinclair::Matchers: RSpec matchers for testing builders (add_method, add_class_method, change_method, change_class_method)
  • A combined end-to-end example

writter: is intentionally spelled that way throughout — it is the gem's actual keyword argument name.

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.