Kit

Kit is a coding agent runtime. It gives the model one tool for writing and running programs.

Kit provides a terminal client, an Agent Client Protocol (ACP) server, an A2A endpoint, and a subagent orchestrator in one static binary.

ACP separates agent clients from agent runtimes, so Kit works in compatible editors and can orchestrate other harnesses without custom integrations.

Fewer model round trips repeat less context and complete more work in each request. In size-matched production tasks, Kit used approximately half the input tokens and active time per hand-written line of Codex CLI or Claude Code ( comparison ).

Reusable subagents. A subagent is a reusable value. You can continue, fork, inspect, and close a subagent. You can require JSON that matches a schema. You can also use Claude Code, Codex, Cursor, or Kit as the subagent harness over ACP.

Open protocols. Kit supports ACP v1 and v2 over stdio, HTTP/SSE, and WebSocket. Kit supports A2A v1 in both directions. It also supports MCP, Agent Skills, and Agent Plugin packages.

Model choice. Kit supports ChatGPT subscriptions through native OAuth. It also supports models through OpenRouter and the Speakeasy AI Control Plane. Use /model to change the model during a session.