Temporary notes in Emacs buffers?

[Marcin Borkowski]

Hi all,

I've been wondering if there is some package which could let me make
"temporary notes" in Emacs buffers, similar to (but different than) the
"yellow notes" in some pdf viewers.

My use case is that I'm making a sweeping change across a pretty large
codebase, and I'd like to make some notes in places I've already visited
/ ones I need to change / etc.

At present, I use normal code comments, however, this is suboptimal,
since I cannot use them in certain modes (occur buffer, JSON).

Ideally, a place with a comment would have that comment highlighted
somehow, and I should be able to go to the next/previous comment, and
list all comments in a file or in the project (think Git repo,
Projectile project or a directory tree).  Also, mass inserting such
comments from an occur/multi-occur/projectile-ag/counsel-rg/etc. buffers
would be great.

What I /don't/ want is modifying the files - the comments might persist
in some /other/, .gitignore-d file, or just disappear on exiting Emacs.

I know bookmark+ has similar features, but I'd prefer something more
lightweight.

Does there exist something like that?  Am I the only one interested in
such a feature?  (I'd be happy to code it myself, though it would take
time, of course.)

TIA,

--
Marcin Borkowski
http://mbork.pl