they tend to build starbases at the jump point where the constructor entered the system rather than where a human player might deem a "good tactical position" would be, such as near his other structures. 

its a pretty egregious flaw to be perfectly honest. combine that with the fact that they don't seem to actually research very many (if any) upgrades from the Fortifications research path and you have a pretty bad AI implementation of the new stuff in Entrenchment. 

from what i can gather the AI builds mines (way way way too many mines) and starbases but thats more or less it. they don't seem to be capable of researching the nice new upgrades for hangars and turrets and they don't seem to ever research the advanced starbase upgrades (like Frontal Shield, or MAss Disorient, or Docking Booms, etc.) they also don't ever seem to use the Auxiliary Government thing so its possible to sneak a cap ship past the the SB and blast a planet to take a system out of operation even with an SB there. 

they still build normal amounts of turrets, hangars, and repair bays though, that hasn't changed in my observation. 

i'm really hoping the next major update (Entrenchment 1.1, or something) has a big upgrade to the AI. its pretty lacking right now. 

as long as i'm on the topic, i've got a few other AI pet peeves that i'd like to see addressed.

1) obsession with neutral extractors. its good that they actually care about these now, but they seem to care WAY TOO MUCH. the AI will send its entire main battle fleet to take out the 4 or 5 light frigates i send to go secure some neutrals. 

2) oblivious to grav well effects. for example, they'll camp out a fleet of 10 carriers in a Plasma Storm (strikecraft launch disabled effect). 

3) still selects cap ships totally at random. i realize its hard to get a good decision making flow chart set up for something this complicated, however, you can at least improve the FIRST cap ship decision. there are clearly some ships that make good first choices (battleships, colonizers) and others that make terrible first choices (support casters like Dunov or Antorak, Carriers in general). 

4) suicidal with cap ships. i've seen AI's fly a level 1 cap ship directly into a 2 pip planet militia with no support. the cap will obviously get blown away and that AI player is basically permanently out of the game because of it. would it be so hard to get the AI to retreat its cap ships when they go to 50% hull?

i noticed this too, and its also very rare (at least in my experience) to see them build the more advanced defenses, like planetary shields, phase stabilisers/nano-weapon jammers or anti-matter restorers... let alone superweapons.

also, in my experience, whatever defenses ARE built, are built in useless locations, or in so few numbers that they're effectively useless.... the only time i do see good AI turret defenses is on pirate bases... but those are probably pre-programmed, and even then, i usually dont take on pirate bases until i have a very large fleet.

and i totally agree with all of transitive's points, im playing an AI map with an AI TEC ally, and he nearly had his ass handed too him, before i moved in and saved his ass, even retaking his original home planet, then pushing back the attacking AI another 4 or so planets so my ally could get a good empire going. at first, my ally had one cap ship, a Dunov, with like 5 colony frigates and a few meagre reinforcements... it took him 20-30 minutes before he started building fleets again, and took him like 1-2 hours before he had enough ships to defend his own planets...

now, in all fairness, i acknowledge that writing AI good programs a walk in the park, but like it was said, original cap ship choices should be pretty easy... and a line of code that says: IF number of planets = < 3 THEN build coloniser cap OR battleship cap (based on whatever details the devs think significant) should ensure he builds an appropriate cap ship to retake his empire

           I also feel that the ai has not ramped up w/ entrechment. Vasari minelayers warp in and dont lay mines,ai STILL doesnt use super weapons. Pirates are a joke mid game.   And neutral colonys on hard and unfair should have hanger,mine,turret defenses, and maybe mini starbases w/ aux government.

They wouldn't need the labs for that because in original SoaSE, neutral colonies had a couple of hanger defenses anyway so why would they need research labs for mines and mini starbases w/ aux government?

He means in the beta, probably. (there were major changes from the original concept in the beta)

I agree that the AI now tend to use mostly starbases and mines for defense, although I have also seen those backed up with turrets.  I am sure that it's just that I am only minimally competent myself, but I am pretty satisfied overall with the AI.  Not that I would mind further improvements...