Client bots can't issue grouped commands

[dgant]

The Brood War engine has some special rules for commands issued to multiple units at the same time. Commanding grouped units allows those units to do things which they can't do individually. Some examples:

• Mutalisk stacking
• Hold Position Lurkers
• The new Stop-Hold Carrier micro to double Carrier DPS
• Half-price Archons
• Magic boxing

The BWAPI module API allows issuing grouped commands via Game.issueCommand().

But the client API doesn't support grouped commands. The front-end splits the commands up because the back-end has no mechanism for receiving commands to more than one unit at a time.

In practice bots have gotten by without Mutalisk stacking or magic boxing (individual commands achieve the same effect), and Hold Position Lurkers may (I haven't tested) be achievable just by issuing hold position commands despite their absence from the command card (according to McRave, this works for workers and XIMP already does it). The Carrier trick and half-price Archons may actually require grouped commands, though.

Another use of grouped commands (yet unexplored) is allowing authors to lower the APM (actions per minute) of their bots to be comparable to human levels, addressing some complaints about bot-vs-human fairness.

[dgant]

https://youtu.be/6W0B0jZEQrc?t=260
A bit more on why the grouped command for Carriers appears to do something that an individual command would not.