reka lets emacs' logic just flow into river. It is a window manager inside of Emacs for the Wayland world.
Background
I spent many years using EXWM, it was great but quite wonky. At some point Wayland became unavoidable (I really need per-monitor fractional scaling!) and I switched to niri, which is one of the highest quality pieces of software in the world.
At some point my friend ezemtsov wrote EWM, which is a full Emacs compositor running as a dynamic module inside of Emacs. It's a great project, but I wanted to see if we can avoid the complexity of a full compositor implementation with the river WM protocol, and classic brain-coding.
What else ... the name? Oh, it's obvious to Russian speakers.
Status
Most things work, and I use reka as my daily driver. The main feature that is still missing is floating windows. There are likely still some bugs and rough edges outside of my particular configuration, though, so be ready for that.
There is no simulation key support, this will need a new protocol on the river side.
Reka does not expose any input or output management to Emacs Lisp right now, and I'm not sure that it will. River has external tools (channel for input management, and kanshi for output management) that are sufficient for me.
If you want something more fully featured, look in the direction of EWM instead!
Using this
You should be a sufficiently committed person to use this. There is no hand-holding!
First, get the source either from TVL directly, or from the mirror:
# clone directly from TVL: git clone https://code.tvl.fyi/depot.git:/tools/emacs-pkgs/reka.git # or clone from Codeberg mirror: git clone https://codeberg.org/tazjin/reka.git
After that, build the Rust project (you need pkg-config and libxkbcommon),
and make yourself a script that launches Emacs approximately like this:
emacs --directory $reka_src/target/release --directory $reka_src/lisp ...
and then pass that script to river's -c flag on launch. In your Emacs config,
make sure to (require 'reka) and then (reka-enable).
Contributing
The upstream code location is in the TVL monorepo. Issues can be reported to the TVL bug tracker for those that have an account here, or on the Codeberg mirror.
Reka follows the standard TVL contribution guidelines. Patches must be written by real humans using fleshy brains.