Macro image placeholder call is not signed

The call in question is the following:
https://developer.atlassian.com/static/connect/docs/modules/fragment/image-placeholder.html

For our Lucidchart Add-On, we wanted to make the placeholder dynamic, so that it displays a thumbnail of an actual diagram being inserted right inside the editor. This provides a much better user experience, especially if there are several instances of the same macro inserted in a page. See the attached screenshot for illustration.

The problem is that currently the placeholder call is not signed, meaning there is no auth data coming with it. To work around it, we currently actually store the consumerId among other data inside macro parameters to make sure it gets passed with the call, and use it to fetch the right diagram thumbnail, *bypassing the normal authentication flow*. We obvuously wouldn't want to keep such solution out there.

aholmgren, cwhittington, pbrownlow we discussed this during the office ours at the summit, you mentioned that currently assume that placeholders are always static images, but let's work this out. Thanks so much for your time going through our issues!