org-msg VS lsp-mode

There is also org-msg as another option (haven't tried both so can't compare).

org-msg replaces a lot of message composition behavior, so it's not a big surprise that it doesn't respect that variable. Make sure you're referencing org-msg's README while customizing it.

Funny, just dealt with the whole O365 authentication just this week. With moving to 2 factor authentication you need to use OAuth 2 to do anything with it. I have my (work) O365 email forwarded, so I do have normal IMAP access. I use isync/mbsync [1] to receive email, goimapnotify [2] to get pushed new email, read/reply/etc with mu4e [3] and org-msg [4] and org-mode, and until recently just plain SMTP to send mail. This last part will break with 2 factor, but found oauth2ms [5] to set up the OAuth to work with O365 SMTP. The trick was to find the "tenet ID" from the Azure page of your organization and to use Thunderbird's credentials [6] (or another mail program, since I can't make new app registrations on Azure to have my own "application"). That should also allow you to use IMAP with OAuth 2 as well, but haven't done that since I still have the forwarding. (As usual, I think the Arch Wiki [7] covers most of this too.)

[1] http://isync.sourceforge.net/

[2] https://gitlab.com/shackra/goimapnotify

[3] https://www.djcbsoftware.nl/code/mu/mu4e.html

[4] https://github.com/jeremy-compostella/org-msg

[5] https://github.com/harishkrupo/oauth2ms

[6] https://hg.mozilla.org/comm-central/file/tip/mailnews/base/s...

[7] https://wiki.archlinux.org/title/Isync#Using_XOAUTH2

I'm using org-msg like this (great package btw, doesn't get enough attention if you ask me):

https://github.com/jeremy-compostella/org-msg/issues/1#issuecomment-426415584 is one of the things which pushed me towards org-msg.

I also tried to the solutions suggested  and , but nothing worked. I moved the (setq lsp-keymap-...) line outside (and before) use-package. I also used :config (define-key lsp-load-map...) in my use-package block. But none of them worked.

Not sure how much this might help, but lsp-mode has lsp-yaml-select-buffer-schema and lsp-yaml-set-buffer-schema commands to pick schema from a list or set from a URI. Checking the source of them might give some hints about how the same could be implemented in eglot?

Beyond that you might as well embrace the suck and install autex with a language server: https://emacs-lsp.github.io/lsp-mode/

Smart completion these days is done primarily through LSP. eglot is fairly minimal but built-in as of 29, also available via GNU Elpa. lsp-mode is another option with more integrations and a bit more fleshed out.

lsp-mode: https://github.com/emacs-lsp/lsp-mode/issues/2080

Are you running emacs-29? It has numerous speed-ups compared to emacs-28 and older versions, many of them coded by Mattias Engdegård, e.g. commit def6fa4246. I have a fresh build of emacs-29 running on Linux and a new mac with an M1 CPU, and it's stupid fast. I don't use the native-comp feature. I rarely notice any hesitation or slowness. I don't use Elpy. I do use lsp mode.

Since you are doing code development, the first things to go for would be setting up your emacs packaging (installing use-package and melpa (use-package's documentation covers this) so you have more packages to choose from (do be careful to not just pick things willy nilly but research them a bit first)) and then setting up lsp-mode. lsp-mode lets you use LSP servers for the specific programming languages you work with in a somewhat unified fashion. You then need to install and setup the LSP servers for the languages you use, and possibly install language specific Emacs packages as support (note, Emacs has builtin functionality for many).

And first of all, I'm trying to understand, how is it connected to https://github.com/emacs-lsp/lsp-mode? I'm sure, that existed lsp implementations already parse source code. Why TreeSitter?