Some news to share. I think I have this new AI-AI combat working as expected. If you check out the log messages you'll note several debug messages included that I've been using to help understand what the AI is doing.
From the battle summary we see the at-start corps and factors involved, France with 28 attacking Prussia with 18. I'm using this strength information to calculate battle odds for the AI sides, which now helps them make less reckless chit selection; e.g., France isn't picking Esc Assault and Prussia isn't picking Withdraw at 1:1. The calculated losses for each round are being correctly reported in the summary. Prussia broke after Round 2 with morale -1.77, and France pursued. Prussia took 1 cav loss, again correctly reported in the summary.
Getting the combat screen battle messages for human-AI and AI-human battles correct as well as the summary messages took a bit of effort over the past couple of weeks. Long story short, the way the combat screen handles combat and the way AI-AI combat is handled off-screen is slightly different, and finding and fixing the discrepancies took a while.
I need to playtest more and see some AI-AI naval battles to verify all else is well, but so far so good.
Empires in Arms Development Team