> ## Documentation Index
> Fetch the complete documentation index at: https://www.latentcast.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Tuning by chat

> Change a finished story by asking for it — how the chat works, what it does immediately, and what it asks you to approve first.

**Where:** the round blue button at the bottom right of a story, or **Tuning Chat** in the header

The <Tooltip tip="The chat beside the preview. Tell it what to change and it edits the Video Story for you, with undo."><strong>tuning chat</strong></Tooltip> is how you change a story without hunting for the
right control. You say what you want in ordinary words and it makes the change, shows you the
result, and gives you a way back.

> *"Make the opening punchier."*
> *"Replace the background in scene 2 with something darker."*
> *"Add our logo when I mention the partnership."*
> *"Drop scene 4."*

It reads the story before every change, so it is never working from memory of an earlier version.

## Two kinds of change

This is the distinction to hold on to, because it tells you when something will cost time.

**Immediate changes** happen as you ask. Moving the presenter, hiding a background layer, changing a
title's wording, reordering scenes, adjusting timing. The preview updates in seconds and the chat
tells you what it did.

**Changes that need approval** show you an <Tooltip tip="The chat's confirmation step before anything slow or costly runs. Nothing happens until you approve it."><strong>approval card</strong></Tooltip> first: what
will be generated, for which scene, and what it will replace. Generating a new image, animating a
background, rewriting narration. **Nothing runs until you approve the card**, and cancelling costs
nothing at all.

<Note>
  That rule is the whole safety model of the chat. Anything slow or expensive stops and asks. Anything
  instant and reversible just happens.
</Note>

## Undo, and checkpoints

Every change the chat makes can be undone from the chat itself. One approval is one undo, even when
the change touched several scenes at once.

For anything larger, save a <Tooltip tip="A saved point in a story's history you can return to. Cheaper than caution: save one before a big change."><strong>checkpoint</strong></Tooltip> first, using **Save checkpoint**
above the preview. A checkpoint is a named point in the story's history that you can come back to
from the **History** tab. Checkpoints are cheap and there is no reason to be sparing with them.

## Bringing in your own material

Drag an image, a video or an audio file into the chat and it is stored with the story, ready to
place. Uploaded images are used exactly as you supplied them, never regenerated.

Audio files are stored but cannot yet be placed in a story. That is on the way.

## Long-running work

Generating a video background takes minutes rather than seconds. When you approve one, the work moves
to the background and the chat stays usable. A placeholder holds the slot in the preview, and the
real clip swaps itself in when it is ready. The activities button in the header shows what is still
running.

## What the chat will not do

Deliberate boundaries, so you do not spend time trying:

* **It cannot edit a flow.** Scenes built as a step-by-step sequence are owned by their own editor.
  The chat will re-align a flow after a script change, but will not restructure one.
* **It cannot pick avatars and voices.** Those are set on the story itself, and the chat will point
  you there.
* **It cannot turn an image into a video or edit an existing clip.** It can generate a new one.
* **It stays on the subject.** It will decline things unrelated to the story you have open.

## Limits at a glance

|                                    |                                |
| ---------------------------------- | ------------------------------ |
| Uploads                            | Images, video, and audio files |
| Shortest background a layer can be | 1.5 seconds                    |
| Generated video clip length        | 5 to 15 seconds                |
| Messages in one conversation       | 40, then start a new one       |
| Time to generate an image          | About 25 seconds               |
| Time to generate a video clip      | 1 to 15 minutes                |

## Next

<CardGroup cols={2}>
  <Card title="Backgrounds" href="/docs/guides/stories/backgrounds">
    Change what is behind the presenter.
  </Card>

  <Card title="Narration" href="/docs/guides/stories/narration">
    Change what the presenter says.
  </Card>
</CardGroup>