I wanted a notebook app that:
1) doesn't do any network connectivity/syncing (it runs in a vault Qube on my QubesOS workstation)
2) is encrypted at rest (something like KeepassXC etc) - and I know SQLCipher well already
3) has version control (not just autosave, but the ability to view and revert to older versions)
4) supports Markdown
Like most tools, through active use it quickly grew beyond that. For example, I wanted to:
a) be able to move 'unchecked' checkbox TODO items automatically to the next day as the click ticked over midnight, so that my remaining unfinished work was at the top of tomorrow's list
b) add documents
c) tag pages and documents with common tags
I'm a contractor, and I log my time all day long for different clients. I realised I was 'planning' my work in Bouquin, but still logging my time in a crusty old local Redmine instance. So, rather than spread my effort across tools, I added time logging (including a Pomodoro-style timer within the app).
That led to me realising I use a separate invoicing tool at the end of the month, as well. So, I added an invoicing feature to feed off the logged time, and also auto-save the invoices into the Documents system :)
Most of these features are 'modular', they can be turned on or off.
In the end, I've been able to consolidate a whole lot of functionality into one app, and I'm much more productive as a result.
There are other features too such as Reminders (which do support sending to a remote webhook, as well as flashing up on the screen - invoices also auto-add reminders for the due date if they aren't paid by that date).
More features can be found at https://git.mig5.net/mig5/bouquin#features and more docs at https://git.mig5.net/mig5/bouquin/wiki/
In retrospect, I maybe shouldn't have chosen PySide6 - even though I know Qt, it sometimes is a real hassle to work with (especially the 'live markdown' rendering). It's working okay, but doesn't look great on MacOS, because of something MacOS does with font sizes