# Core concepts

> The few ideas behind the Cosmos Agent API and Line CLI, explained once.

## Account ID

You sign in to the [Console](https://console.clatterlabs.com) with your Clatter Labs account. Each account has a permanent **Account ID**, like `CL-7K2M9QXA`, shown with a copy button on the Console's Home and Settings pages. The Agent API asks for it in the `X-Clatter-Account` header next to your key, so that a leaked key alone is not enough to act on your account.

## Cosmos Agent and runs

**Cosmos Agent** is an AI coding agent you call over an API. You describe a task; Cosmos plans, writes and runs code, browses, and saves files until it's done. One task is a **run**. A run can split work across parallel **sub-agents** and takes up to 150 steps.

## The cloud computer

Every account has its own **cloud computer** that runs work for it: a Linux terminal and files, a Chromium browser, a database and storage, hosting at `<name>.clatterai.com`, and Cloud Repos for code. Runs use it; you never have to set it up.

## SuperCosmos tiers

Cosmos and Line CLI think with **SuperCosmos by Clatter Labs**, which comes in three tiers:

| Tier | Best for | Input / 1M tokens | Output / 1M tokens |
| --- | --- | --- | --- |
| Flash | Quick edits, answers, everyday steps | $1.60 | $3.40 |
| Max | Planning, debugging, multi-file changes | $1.80 | $3.80 |
| Heavy | Hard bugs, long builds, deep reasoning | $2.00 | $4.40 |

**Long-context input above 262K tokens: 1.5×** (SuperCosmos): a request whose prompt is over 262K tokens bills its whole input at 1.5× the rate above.

`auto` lets Cosmos pick. See [SuperCosmos models](/models/overview).

## Credits

App usage (Line CLI, Cosmos Agent, Cosmos Agent on Telegram) is covered by your **plan** (usage windows and a weekly limit on paid plans, a monthly allowance on Free); API usage (Model API, Agent API) is paid from **one credit balance per Account ID**, in US dollars. New accounts get $5 of free credit ([Plans and credits](/billing/credits)). Tokens are billed at the tier each call actually ran on; computer time, tool actions, browser time and storage writes have their own small rates. When the balance runs out, metered calls answer `402 out_of_credits`. See [Credits and billing](/billing/credits).

## API keys and permissions

Agent API keys (`clsk_…`) are made in the Console. Each key has **permissions** and its own **rate limit**:

| Permission | Allows |
| --- | --- |
| `runs:write` | Create and cancel runs |
| `runs:read` | Read runs, their events and results |
| `account:read` | Read your credit balance and usage |