> ## Documentation Index
> Fetch the complete documentation index at: https://actelos.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Specification Overview

> What the cyrnel sdk is and how to use it

`@cyrnel/sdk` is the TypeScript package every cyrnel module is written against.
It defines the data shapes cyrnel exchanges (services, tools, execution
state) and the interfaces that adapter and environment modules implement.

## Who implements what

* **Adapter authors** implement [`AdapterModule`](/cyrnel/specs/adapter-module).
* **Environment authors** implement
  [`EnvironmentModule`](/cyrnel/specs/environment-module).
* **Cyrnel itself** implements [`EnvironmentBindings`](/cyrnel/specs/environment-bindings),
  which is what an environment module *calls into*.

## Module Manifests

Every module exposes metadata (id, name, type, description) via a
`module.json` file on disk, plus schemas and a factory via a default
code export.

* **Built-in modules** use a default export that bundles both schemas
  and `instantiate`:

  ```ts theme={null}
  export default {
    configSchema: { type: "object", properties: {} },
    secretsSchema: { type: "null" },
    instantiate(): AdapterModule {
      return new MyAdapter();
    },
  };
  ```

* **Custom modules** declare basic metadata in `module.json` and the
  schemas + factory in a default export from their entry file.  See
  [Writing a custom module](/cyrnel/specs/writing-custom-modules) for
  the full layout.

Config and secrets schemas are **not** part of `module.json`; they come
from the code export instead. This ensures schemas are kept close to the
logic that consumes them.