I worked on some results jointly with other coauthors. We jointly wrote a first draft of the article, and we started discussing where to submit. Time passed, and there was not much impulse to finish the article. We moved on to other projects and forgot about it. Our shared draft was never touched again. I assumed we lost interest.
Until, a year or so later, I found my coauthors wrote another article on the same result and published it. To be clear, it is a different text – I do not think any of the text is mine – but it follows the same structure and main idea that the document we discussed and drafted together.
What to do now? I imagine this is a common situation: multiple people work on an idea, but a subset takes the idea to a different place and finishes an article. I do not know if I would feel comfortable being added as a coauthor: I have not written this. At the same time, it does feel unfair to have put so much effort and time into a project without my name. Asking them to add an acknowledgement feels a bit unsatisfying to me (although I feel it is the least they could have done). Is there any better option? Apart from contacting them, is there any obvious step I am missing?