iw4L/docs/DUO.md

Two local players through the master

make duo builds the game and opens a host and a client in separate 960×540 windows. It uses IW4L_GAMES and the IW4L_MASTER_* connection settings from .env, like make menu. The configured master can be local or remote.

make duo
make duo ZONE=iw4:mp_afghan MODE=dm
make duo HOST_CMDS='spawn 0; wait 20s; dump host' CLIENT_CMDS='spawn 0'

Every run creates a fresh public lobby on the master. The host's actual lobby ID is printed and saved in iw4l-artifacts/duo/<run>/lobby.id; the client joins that ID directly. The host starts the match only after both sides report lobby membership. There is no browser-row selection or fixed lobby startup delay. GSC still owns classes, countdown, scoring, death and respawn.

HOST_CMDS and CLIENT_CMDS run after wait world; both default to spawn 0. During the run, type into the terminal:

host dump host
client dump client
both screenshot
host hold +attack
host release +attack
quit

Each line is forwarded to the regular console queue. Semicolons separate commands; ! retains its normal meaning of bypassing a wait. quit stops the pair. Closing either game window also ends the pair. Logs, settings, dumps and screenshots are isolated under the run's host/ and client/ directories. On Unix, the asset cache is shared through symlinks.

For other launch tools, IW4L_CONSOLE_STDIN=1 enables line-based console input. IW4L_MASTER_STATUS_FILE=<absolute path> writes the current master state as key=value lines (state, room, members, in_match) using atomic replacement. ui_join_lobby_id <id> submits the normal master join request; set ui_mapname and ui_gametype to the lobby's selection first. Admission remains the master's responsibility. These interfaces do not bypass networking or GSC.