I've seen a lot of variations of this, and i myself would love an open-source personal/project management system, but they all ignore just how crucial UX is in one way or another. They either make it so simplistic that you may as well just be using an actual text editor, or they make it so complex with assumptions that everyone cares about things like recurrence and goal tracking. Not hating on this project at all, but i've used about every single system out there that's been built, if often only to compare, critique, and work out how i should build such a system.

There are currently only two absolute truths to what i feel is necessary to combine power and ease of use, and honestly i think i learned that from git more than any todo list, or habit builder, or project management app, but it applies very well to the things that an intelligent personal/project management system needs to be powerful and accessible.

1. The source of truth should be an append only log of events, in this way state can be infinitely rebuilt and reused. That said, rewriting history could be an allowable function, such as the way a distributed git branch COULD be rewritten, but is generally avoided and requires serious intent to do so. I once considered (and built) a file-system driven personal management system, but too much valuable data is lost when your source of truth is the current state rather than the 'story'.

2. The UX needs to be both simple & powerful, with graceful complexity. As a simple example, allowing the ability to tag todos is a good idea, but you shouldn't have a tag sidebar taking up real estate if none (or even just a couple) of your todos are tagged. There should be a combination of enabling features and having the system be able to build a suggestive state based on the actions you take in the app in an attempt to delight users and give them what they would presumably expect given the path they've chosen. Think of the user experience as a Choose Your Own Adventure novel, where the choices they make progressively shape it.

That said, i humbly admit that aside from a successful career making other people money, i haven't yet built a successful product of my own, so take that opinion/advice with a grain of salt. I applaud your efforts and i hope one day the world has a great piece of software that makes it delightful to get shit done. If anyone is passionate about making that software, i'd love to talk to you, as i recently left my position as a software architect and have been doing my damnedest to avoid working for another shitty S-Corp that claims to have an altruistic vision while consistently putting profit over people.

(As an aside, i do realize that git does not really use an append-only log, in the way that databases and message brokers do, but it is very similar, and in many other ways is much more robust. The point isn't so much that the record of what happened should be absolutely immutable -- especially if one has their heart set on rewriting history --, but to keep the 'story' intact so that you can build a meaningful application state that improves over time.)

(As a last aside, i realize in English, the word 'i' is traditionally capitalized, i won't go into why i refuse to capitalize it, though i am open to discussing it, but i just wanted to point out that it's intentional, not a grammatical error. Throughout my professional life i've refused to capitalize and it hasn't hurt my career.)