"Spacedock" improves the ship designs the AI creates.
Shields & Armor
In vanilla Stellaris, how much armor or shields an AI puts on its ships is determined solely by their personality. Erudite Explorers for instance want 70% of their defenses to be Shields, and only 30% as Armor. Even if they had level 5 armor technology and only level 1 shields, they would still only dedicate one defense slot to armor, and put lvl 1 shields in all other slots, in an attempt to reach 70% shields at all costs.
Spacedock changes this. There are now five variations of each AI personality, covering the spectrum from a heavy shield focus over a balanced approach to a heavy armor focus. Which personality is picked, changes during the game based on two main factors:
At the moment you can see on the F1 Contacts screen which defense plan the AI is currently going for. D for Default/Balanced, A or AA for an armor focus, S or SS for a shield focus. I'll probably remove that at some point. For now I'm using it for myself to be able to observe AI behavior more easily. It's also a way for you to verify the mod is in fact active and enabled. That can sometimes be a problem these days with the new launcher...
Weapons
In vanilla Stellaris, similar to with defenses, some of the AI's weapon preferences are hard set by its personality, and often it just uses a random mismatch of whatever weapons it has available.
Spacedock on the other hand follows a similar principle as with shields & armor - now its weapons choice is determined by two main factors:
There are various other factors going into its decision making, too many to list here. Some examples are: