# ModelCtx

> ModelCtx (modelctx.ai) is an open data model for AI agent context (CCM), converters from agent clients into it, and ModelCtx Studio, a web app (app.modelctx.ai, or self-hosted with `ctx serve`) that shows what each model call actually saw. It is not an agent runtime and not a production observability backend.

## Core ideas

- Thread: one context window (main agent, subagent, or fork).
- Turn: one unit of work started by an input.
- Item: an atomic record in a turn (userMessage, agentMessage, reasoning, toolCall, contextCompaction, contextInjection).
- Memory: a record in a store shared across threads.
- The context window is derived, never stored: model-visible items since the last contextCompaction, plus thread instructions.

## Links

- [Source code](https://github.com/modelctx-ai/modelctx): Apache-2.0
- [CCM specification (README)](https://github.com/modelctx-ai/modelctx/blob/main/packages/spec/README.md)
- [Design document](https://github.com/modelctx-ai/modelctx/blob/main/docs/design.md)
- [Roadmap](https://github.com/modelctx-ai/modelctx/blob/main/docs/roadmap.md)