> For the index of every page in Orbital's docs, read https://docs.runorbital.dev/llms.txt.

# Write your first workflow

> Run the smallest complete workflow: one agent step and one terminal

Write a [workflow](/workflows/) with one agent step and one terminal, then run it. It is the smallest workflow that does anything.

```toml title="minimal.toml"
version = 3
entry = "steps.hello"

[steps.hello]
prompt = "Reply with one sentence explaining the goal: {{ inputs.goal }}."
next = "steps.done"

[steps.done]
kind = "terminal"
```

`version = 3` says which workflow format the file uses, and `entry` names the step the run starts at. `hello` is an agent step: a step with a `prompt` and no `kind`. Its `next` sends the run to `done`, a terminal, which ends the run successfully. A reference to a step is always its full path in quotes, such as `"steps.done"`. Every other guide builds on this with more steps and routes.

The prompt asks only for a sentence, so the agent has no reason to change files. To keep a step from changing files, say so in its prompt. With Codex, a style can also give the step a read-only sandbox with `codex.sandbox_mode = "read-only"`.

![hello → done. One prompt followed by a successful terminal.](/minimal.svg?v=b911ee569f)

## Before you start

You need a harness you have signed in to, and a project in Orbital. Any project works. It does not need to be a Git repository, unless you run the example with Codex, which needs one. See [Projects and folders](/projects/).

## 1. Save the workflow

[Download the example](/minimal.zip) and unpack it into your workflow library, `~/.orbital/workflows/`. Keep every relative path. You can also [download minimal.toml](/examples/minimal/minimal.toml) on its own.

## 2. Validate it

```sh
orbital validate ~/.orbital/workflows/minimal.toml
```

Validation calls no agent.

## 3. Start a run

Choose **New task** and pick any project. Choose the `minimal` workflow. One project serves every example.

![The Start page asks what to do in the selected project, with a box for the goal, a preset picker, a workflow picker and a Chat or Workflow switch.](/screenshots/start-page.webp?v=7454bfb8bf)

*Pick the workflow beside the goal box.*

Set the goal to "Explain what a workflow is", and start the run. The `hello` step returns a sentence, then `done` ends the run successfully.

## Related

- [Write prompts](/workflows/write-prompts/): read run values in a prompt.
- [Add branches](/workflows/add-branches/): send a run to different steps.
- [Step kinds](/reference/step-kinds/): the kinds of step you can add.
- [Research report](/examples/research-report/): a workflow that touches no code.
- [Workflows](/workflows/): where Orbital finds workflows and how to validate them.