Assuming a qmd file `index.qmd`

```
---
title: "Test"
format:
  html:
    self-contained: false
---

# Hello

World.
```

Running `quarto render index.qmd -t html` (or `preview`) generates `index.html` and `index_files/` on which it relies.
However, generating a different output format from the same document, e.g. `quarto render index.qmd -t pdf` deletes the `index_files/` folder.

2022-03-14T12:29:30Z
jmbuhr
closed
Rendering a self contained format after a non-self-contained format deletes _files folder needed by first format
https://github.com/quarto-dev/quarto-cli/issues/418