Several years ago (perhaps at least 5, possibly over 10) I came across an article in which the author described a concept OS. It included a database for the filesystem with the hierarchy determined not only by specific file paths, but also optional keywords associated with the files. Accessing the web may also have been abstracted via that DB. Apps were described as UI views on that DB, and all data (including views' states) was natively automatically synchronized across a user's devices. The author was at the time also working on a prototype, perhaps in JavaScript.

I'd love to find and give it another read, and see what progress there might have been on the implementation, but it's a challenge to search. It's very likely that I discovered that article via HN. It's also possible that I "hallucinated" parts of the concept. But if it's out there there's a good chance someone else here has come across it and perhaps remembers the source. Or something similar. Anyone encountered or any thoughts on how to search further?