# Concepts

> Agent, machine, conversation, turn, channel, connector, skill, engine and plan — the vocabulary of Ghosty Studio.

URL: https://www.ghosty.studio/en/docs/concepts

Eight words are enough to understand everything else.

## Agent

The identity: name, persona, engine and model. An agent is **yours**: it lives in your account, and from there it is activated on whichever channels you want it to work in. The same agent can answer on WhatsApp, in a Teams workspace and in your editor without being duplicated.

## Machine

Each agent runs in its **own isolated machine**: its own disk, its own terminal, no neighbors. That is where it reads your files, runs code and stores what it learns.

- **It sleeps on its own** when nobody is talking to it and **wakes on the first message** (a few seconds). You don't pay for time asleep.
- **It persists**: what the agent wrote to its disk is still there when it wakes up.
- **It recovers**: if the machine is lost, Studio recreates it with the account's history.

Disk limits and how many machines can be awake at once depend on the [plan](/planes).

## Conversation and turn

A **conversation** (`session`) is a thread with memory: the agent remembers what was said in it. A **turn** is what happens between your message and its final reply.

A turn is not an HTTP request: the work lives on the server. You send the message, get `202 Accepted` right away, and follow progress through an [event stream](/en/docs/api/events) you can connect to, disconnect from and come back to without losing anything. A turn can last seconds or an hour, and you can [cancel it](/en/docs/api/reference).

Within a turn the agent may ask for **permission** for a sensitive action. If your client knows how to render that question, it answers it; if not, the turn runs in automatic mode.

## Channel

Where the message comes in from: [WhatsApp](/en/docs/channels/whatsapp), [Teams](/en/docs/channels/teams), the web chat, an [embedded widget](/en/docs/channels/embed), an [editor over ACP](/en/docs/protocols/acp) or [another agent over A2A](/en/docs/protocols/a2a). The agent is the same; what changes is the context it is given and which tools it is allowed to use (fewer on a public channel).

## Connector

An external account the agent can access **on your behalf**: Google, Canva, Spotify, Odoo… Connectors belong **to the account, not to the agent**: you connect Google once and any of your agents can use it. See [Connectors](/en/docs/connectors).

## Skill

A packaged instruction that teaches the agent to do a complete task — produce a designed PDF, clone the layout of a Word file, proofread spelling — with the tools it already has. Skills live in the agent's machine and are read when the task calls for them.

## Engine and model

The **engine** is the harness that runs the turns; the **model** is the brain that answers inside it.

| Engine | Models | When |
|---|---|---|
| Claude | Opus, Sonnet, Fable | Long work with documents and code. |
| DeepSeek | V4 Pro, V4 Flash (with vision) | High volume at low cost. |
| Goose | whatever you configure | Editors over ACP, MCP extensions. |
| Lite | Claude, DeepSeek, OpenAI | Multi-provider; it is the engine of the mobile app. |

You can use **your own provider keys**: they are stored encrypted in your account's vault and only injected into your agent's machine.

## Plan and usage allowance

Each plan includes a monthly token allowance. When it runs out, new turns respond `402` with the reason and the agent does not start work it won't be able to finish. See [Errors and limits](/en/docs/api/errors-and-limits) and [/planes](/planes).