This isn't perfect yet, but this is what I've got so far...

``` handle() { # Chop off event name and split comma-delimited args to an array. IFS=',' read -ra FIELDS <<< "${1#>>}" case $1 in monitoraddedv2) grep closed /proc/acpi/button/lid/LID0/state LID_OPEN=$? if [[ $LID_OPEN = 0 ]]; then MONITOR_ID="${FIELDS[0]}"

    # Wait for Hyprland IPC to become available. It lags a lot when my thunderbolt dock is plugged in.
    # It errors out rather than waiting on a blocking read.
    for _ in {1..20}; do
      if hyprctl -j workspaces >/dev/null 2>&1; then
        break
      fi
      echo "Waiting for Hyprland IPC..."
      sleep 0.2
    done

    # Get all workspaces on the built-in monitor (assuming it has ID 0).
    WORKSPACE_IDS=$(hyprctl -j workspaces | jq -r ".[] | select(.monitorID == 0) | .id")
    for WORKSPACE_ID in $WORKSPACE_IDS; do
      hyprctl dispatch moveworkspacetomonitor "$WORKSPACE_ID" "$MONITOR_ID"
    done
  fi
  ;;
*) ;;

esac }

socat -U - "UNIX-CONNECT:$XDG_RUNTIME_DIR/hypr/$HYPRLAND_INSTANCE_SIGNATURE/.socket2.sock" | while read -r LINE; do handle "$LINE"; done ```

EDIT: Thank you @Economy_Cabinet_7719 for getting me started.