With the auto-evo exploration tool I’ve seen it pop up quite a few times I think. It’s also common for a AI species to split off the player once the player has evolved a nucleus. But you’re right, the AI has trouble evolving one in a regular playthrough if it can’t rely on the player to “help” it.
I’m glad the proposal is reasonable. And I agree, it doesn’t need to be implemented right away in tandem with endosymbiosis for the player. It can also be implemented a few updates later, and in the meantime people like me who are bugged by a “canonical” inconsistency in the game have to bite that bullet for some time. It would certainly help for immersion if the AI seems like it has the same logic applied to it as the player (even if the systems work differently), but it’s not like it would be an extremely jarring experience if the AI evolved eukaryotic organelles which it theoretically couldn’t for a few releases.
some rambling, feel free to ignore
I think this simple addition could lead to a few interesting emergent situations. It would mean that membranes which would block engulfing could be initially powerful, but would prevent a species from unlocking the powerful eukaryotic organelles. That way they might be dominant for a few generation, but would eventually face competition from species which first went for the eukaryotic organelles and only later evolved the engulfment-blocking membranes.
It’s exiting because other it adds a new kind of dependency of adaptions. The nucleus/eukaryotic organelles dependency is a positive one while this engulfment-blocking membrane/eukaryotic organelles dependency would be a negative one. Still, it feels like it wouldn’t be frustrating as it only takes one generation to switch to a membrane type which allows for engulfment.