# Preview and check a workflow

Use **Checks** to find definition problems and **Preview workflow** to follow a path with sample data. Preview does not send messages, change contacts, run lookups, or create a live run.

> Automations is in Early access. Your workspace permissions determine which actions you can perform.

## Review checks

1. Select **Checks** in the editor. If problems are already known, the button shows an issue count instead.
2. Open a reported problem to find the affected step or field.
3. Correct missing values, invalid connections, or expressions that reference unavailable data.
4. Select **Check again** after editing and review the current result.

Errors can block publication. Warnings and suggestions can identify uncertain data or a questionable failure path without blocking publication. Read them in the context of the intended workflow.

Saving an unfinished draft can succeed while checks still report errors. A saved draft is not evidence that it is ready to publish.

## Preview a path

1. Select **Preview workflow** in the editor header to open the preview panel.
2. Choose or edit the trigger sample for the scenario you want to inspect.
3. Supply sample outcomes for actions and waits along that path.
4. Select **Preview workflow** inside the panel to run the simulation.
5. Expand **Previewed path** and select a visited step to inspect its inputs and result.
6. After changing data or a sample result, select **Refresh preview** to explore the new path.

Conditions and value mappings are evaluated using your samples. Actions use simulated results, and waits use simulated outcomes. A wait preview does not pause for the real timeout.

A sample must match the selected node and output. After changing a node, event schema, or template, repair any sample that no longer matches it. Samples on an untaken path can still require repair before preview succeeds.

## Inspect one step

Select a step to inspect **Step preview**. A messaging step also offers **Message preview**; expand **Test with sample data** below it to choose a sample. Select **Preview step** to calculate the result, or **Refresh preview** after making changes. Use **Set sample result** when a later step needs an illustrative output from that action.

Prepared inputs show what the action would receive. A sample result shows what you supplied as its hypothetical response.

For a stored message template, inspect its published content and parameter mappings.

## Interpret the outcome

| Preview message                               | Meaning and next action                                                                                 |
| --------------------------------------------- | ------------------------------------------------------------------------------------------------------- |
| The preview reached the end of this path.     | The simulation reached an ending without an unhandled failure. Check that it took the intended path.    |
| Stopped at a step that needs a sample result. | An action or wait needs a sample outcome. Inspect the prepared input, then supply a sample to continue. |
| The preview reached a failure.                | An unhandled sampled failure or a configured failed exit ended the path. Review the failure handling.   |
| Review the highlighted step.                  | A definition or value problem stopped the preview. Correct the reported problem.                        |
| This event would not start this workflow.     | The sample event does not match the trigger. Review its name, data, and filter.                         |

Preview follows one path at a time. Test the success, rejection, missing-data, and timeout cases that matter to the workflow. An error handled by a failure path can produce a completed preview.

## Keep simulation separate from real runs

Preview can use unsaved editor changes. Saving preserves draft work and samples; it does not turn the sample into a real event.

**Start run** executes the published version with real actions and applicable charges. Its results appear in **Runs** and metrics. Preview results do not.

## Next steps

- [Publish and manage automations](/docs/guides/automations/publishing).
- [Inspect runs](/docs/guides/automations/runs).
- [Troubleshoot an automation](/docs/guides/automations/troubleshooting).
- [Browse the Automations guides](/docs/guides/automations).

## Related resources

- [Preview your first automation](/docs/get-started/automations) (docs)