I think aurora knives might mean harnessing solar flares to use as defences. Also I think the bit about the gate to the garden is unrelated to the Black Garden. I think it just refers to the solar system and the perimeter defences. I'm not sure if anyone in the lore is referring to the Darkness. It seems like a term exclusive to post-Collapse propaganda. The object that Rasputin detects outside the solar system is more likely to be the Traveler. The gardener could just be another AI. I'm not sure about this though. Admittedly 'gardener' sounds like a good name for the Traveler if it gird a it'd terraforming planets - but then why not just call it the traveler if that's what 'we called it' ?