Linux-to-Linux keyboard/mouse forwarding over ssh. Type/click on host B, have the events land on host A. ssh is just the pipe carrier; the wire format is HID-shaped so non-Linux ends can be added later without a protocol break.

uv sync
uv run evpipe-send --help
uv run evpipe-recv --help

Sender needs read+grab access to the source /dev/input/event* nodes (usually the input group). Receiver needs read+write on /dev/uinput.

uv run evpipe-send --list-devices                  # pick paths
uv run evpipe-send --kb /dev/input/eventXX | uv run evpipe-recv

Press a few keys on the source kb. They appear on the receiver's virtual evpipe: <name> uinput device (visible in xev / Wayland's key logs). Ctrl-C either end -- the grabs are released cleanly.

Run the receiver on host A (where you want the input to land), the sender on host B (where the physical kb/mouse lives):

# On A:
ssh -o ServerAliveInterval=5 -o ServerAliveCountMax=2 \
    user@B 'evpipe-send --kb /dev/input/event3 --mouse /dev/input/event7' \
  | evpipe-recv

ServerAliveInterval=5 ServerAliveCountMax=2 is the load-bearing piece: without it, a hung network leaves the sender holding EVIOCGRAB on B's keyboard, which means the user at B can't type until the TCP stack notices. With it, ssh tears down within ~10s on a stall, the sender gets SIGPIPE -> ungrab path, and B's keyboard returns to the local compositor.

--toggle-chord takes a comma- or plus-separated list of evdev key names. The last key is the trigger; the rest must be held when it transitions to pressed. The trigger event is consumed (never reaches A), and the chord works whether forwarding is currently ON or OFF -- so it also serves as the bailout when B's keyboard is grabbed.

The default is KEY_F10 -- a single dedicated key, no modifiers, no QMK-layer/tap-hold complications. Pass an empty string to disable toggling entirely (always-on, kill the ssh to bail out). If a chord isn't firing, run the sender with --log-level=DEBUG; the log shows which modifiers were missing when the trigger pressed.

ssh user@B '
  evpipe-send --kb /dev/input/event3 --mouse /dev/input/event7 \
              --toggle-chord KEY_F10 \
              --start-off
' | evpipe-recv

--start-off is useful when you want B's keyboard to start out local-only and flip into forwarding mode only after you press the chord.

• Keyboard keys on the HID Keyboard usage page (a-z, 0-9, modifiers, function keys, navigation, numpad, common consumer media keys).
• Mouse buttons 1-8 (left, right, middle, side, extra, forward, back, task).
• REL_X, REL_Y, REL_WHEEL, REL_HWHEEL (incl. hi-res variants).

Anything outside the static hid_map table is dropped at the sender with a debug log line. EV_ABS (tablets, touchscreens) is reserved in the wire format but not yet wired in either direction.

• ~/k/42-evpipe/start-here.md -- project overview, next-tasks list.
• ~/k/42-evpipe/design.md -- full architecture, wire format, teardown.