Thank you to Execute for reporting a subtle loophole that allowed instant battles in certain circumstances. I have given 3 stars as a reward in accordance with the game's responsible disclosure policy. Happy hunting to anyone this motivates. :)
In more detail, the game's default time per attempt is 800 milliseconds. This can become even less too with buffs that increase battle speed, such as the Spirit of Wolf line of buffs. Before this update, the calculation of "how long do you have to wait until you battle again?" rounded down as a way to get second-granularity timestamps. This means that, for instance, a 13.2 second battle actually only keeps your bot occupied for 13 seconds. Another example is that a 0.8 second battle keeps your bot occupied for 0 seconds. In other words, sub-second battles are actually registered as being instant by the game, potentially allowing someone to accumulate wins against multiple bots simultaneously and/or in rapid succession.
To fix this, the minimum battle time is now 1 second. The calculation still rounds down, so a 13.2 second battle will keep your bot occupied for only 13 seconds, but a 0.8 second battle will now occupy your bot for 1 second.
FWIW, I'm not aware of this ever having actually been exploited, but I still awarded stars because this is pretty subtle/sneaky and the behavior is definitely unintended. It's probably pretty hard to exploit this in practice because the battle needs to have exactly 1 attempt[*], meaning the exploiting bot needs decent intelligence to be able to regularly hit first. You also still need to actually initiate battles each time which probably wouldn't be that much faster than just waiting the extra second. A script could certainly abuse this for a lot of quick wins though.
[*] Or maybe even 2 or 3 attempts with the Spirit of Wolf III buff? I didn't test this.