In short this plugin assumes news of the Hai spreads rapidly. Therefore in the late game a small percentage of humans start using their ships in ambient fleets. It therefore adds Hai vessels and many variants (like full Proton SB or Plasma/QuadBlaster Solifuge + many more) as rare additions to almost all human fleets in the late-game (more details below). This makes ambient pirate combat much more spicy and varied, with the tide of pirate battle being turned when a Hai ship from either side jumps in.
Ambient spawn rate of Hai ships should be around or below 10%. The plugin attempts to maintain NPC combat balance by adding strength evenly to opposing fleets (pirate/merchant etc), and maintain vanilla feeling fleet compositions.
It activates these changes after player completes both the missions related to the Solifuge and Pond Strider, and has also completed the main plot.
The general idea behind this change is that news of advanced squirrel aliens in close proximity to humanity would plausibly spread very rapidly and that the more prosperous/badass merchants and pirates will be therefore occasionally seen using their ships in human space.
Now if merchants/pirates start using Hai ships, then by golly gosh the military can't allow themselves to be outgunned and is forced to get on board the acorn train too. Therefore this plugin gives the Republic and FW custom variants of the SB as well as the standard Hai weapon setups. Deep/Syndicate use the Strider in the same way. Militia get nothing because they are poor.
Merchants/navy don't use the Solifuge, but pirates do because... somehow. To be honest I couldn't come up with any plausible process for pirates to get their hands on Solifuges - maybe they could buy from the De-fettered though pirates getting through Hai space seems unlikely - but whatever. It's a cool Hai ship, I didn't want to leave it out, so some Solifuge variants pop up in pirate fleets just because. Also the Proton Solifuge (used by Core pirates) is freaking badass.
This plugin doesn't add Hai outfitted human ships in a similar fashion (BetterVanillaPirates does).
Enjoy!