Made more progress on my weekend project, a tool for generating images like this for social media:
Right now, it's an open source command-line tool written in Go, with a few configurable options. You can find the AGPL-licensed code on GitHub and start using it now!
Next, I hope to add a web-based option for generating images. That'll probably involve some basic server configuration (e.g. only generate graphics with a certain WriteFreely instance name), some image caching to save resources, then a simple API and a plain HTML page that hooks up to it.
I'll first build this for our use case, which is showcasing photos to share on social media pages like Instagram. For that, I need to generate images on mobile and be able to quickly copy over caption text. Then, we'll make it more widely useful to help people spread their writing.
For now, my real day has started, and I'm back to work on features and fixes for Write.as.