Ruby server implementation of the AG-UI protocol (SSE event streaming, run loop, client-tool round-trips, A2UI) for driving CopilotKit frontends from Rack/Falcon.

Binds protocol-smtp's state machine to an endpoint and runs it on the async reactor, one task per connection — what async-http is to protocol-http.

Production-grade coding agent with tool execution, middleware pipeline, context compaction, session persistence, and multi-provider LLM support.

gem_kit-release's `gem kit` command takes subcommands from other gems. This gem adds one, `gem kit plugin`, which prints a page explaining how it got there — and that is all it does. It exists to be read. The whole mechanism is a GemKit::Release.plugin block in lib/gem_kit/plugin.rb and a one-line lib/rubygems_plugin.rb that requires it. RubyGems loads the latter on every `gem` invocation, so installing the gem is the whole installation.

The SMTP command/reply state machine (RFC 5321) and the message it assembles (RFC 5322), over any stream. No sockets and no concurrency: async-smtp binds this to an endpoint, the way async-http binds protocol-http.