Image Handling: Editor vs. Frontend

I’m working with twentytwenty for the first time, and I feel the way images are handled in the editor is inconsistent.

The default behavior of the theme seems to be placing a thumbnail images with a hard 580px width. Assuming I might change my theme in the future to something that has a wider column width, I’d prefer that the width be set to take up 100% of the container instead.

If I insert an image and then set it to Full Size, the measurements of the image in the block details are correct, and in the editor, the image appears full sized, but when saving the post, the image is smaller than the content width of the main column.

Steps to repro this:

* Add image block and give it an image that is larger than 580px.
* Select “Full Size” in the block options.
* Preview or publish. The image will be significantly smaller than the editor preview.

I *can* accomplish what I want by setting the image to be Full Size, and then clicking the control for 100%, but when doing this, the image within the editor is gigantic and escapes the bounds of the editor.

Steps to repro this:

* Add image block and give it an image larger than 580px.
* Select “Full Size” in the block options.
* Editor version of the image goes Gigantor.
* Preview or publish, and the image will fill 100% of the content width.

I wasn’t sure where to report this, because I do not know whether this is a Gutenberg problem or a theme problem, so I thought bringing it up here would be a decent idea. (shrug)

I guess I should also ask: is this working as intended?