# Preview

The preview shows the site with a snippet's unsaved draft running, before the
snippet goes live. Open it with the preview control in the workspace header;
it opens beside the editor.

## What it shows

The preview runs the snippet the selected file belongs to, with every file of
that snippet as it stands in the editor, saved or not. Choose a file inside a
snippet first; otherwise the pane asks you to.

It opens the site's home page with a `?sleek_byte_preview=<id>` query, and
links to the same site keep that query, so you can browse on. On a request
that carries it:

- only the draft runs: the saved snippets of every source are left out;
- the draft runs even when its `enabled` is false, and regardless of its
  environments, schedule and conditions, so it shows on every page; its
  contexts and hooks still apply;
- PHP prints every error, warning and notice on the page, whatever the site's
  `WP_DEBUG_DISPLAY` says.

## Keeping it current

The preview reloads when you save, and while it is open the workspace renews
it each time your changed PHP passes the check, about a second after you stop
typing. A draft with a PHP syntax error keeps showing its last valid state.

## How long it lasts

A preview is stored for one hour. Closing the pane or leaving the workspace
deletes it, and an hourly cleanup removes expired previews together with the
temporary files they leave in `uploads/sleek-byte-preview`.

The draft runs only for the user who opened the preview and for site
managers; anyone else who opens the address sees the site as it is. Safe mode
and `SLEEK_BYTE_DISABLE` stop drafts too.

`Actions_createPreview` and `Actions_deletePreview` create and remove previews
for other tools; see the [REST reference](/docs/byte/reference/rest.md).