"hanger bays" for starports

When a planet has ships in port enemy forces must contend with defending ships b4 invading.  Why doesn't a starbase deserve the same luxury when ships are on the same tile. Especialy when it's a military starbase?

Also, why can't starbases be invaded if a invasion ship is in the attacking fleet? have a chance that the base is taken instead of destroyed and have the base attributes operate at minus 50% (or more) bonus until a number of turns has passed and/or atleast one of your own constructors arrives to repair and assimilate the bases systems completely. Heck the possibility could be new tech(s)

Having an option to commit a starport to "planetary defense production and deployment duty" where the starport only replaces the ships stationed in it at the time of assignment and if the planet has an orbital defense platform then the ships are considered already in orbit at all times and thus recieve the bonuses of any starbases in range.

a starbase defense ai that never lets autoattack fleets tied to a military starbase leave the bonus radius. and the ability to attach one fleet too more than one military starbase and have options to tell the ai not to leave overlaps of 2 (or more if desired) starbase fields.