2022 01Jan 11
It turns out the thing I had been calling "Spacedock" is an edge case of POSSE:
POSSE is an abbreviation for Publish (on your) Own Site, Syndicate Elsewhere
In the spacedock model, the origin server on your PC is your own site, and the spacedock relays are "Elsewhere".
This is good news because it means there is prior art and people are interested in this type of thing.
It's also bad news because it's not the first time I had a really great idea, worked on it, talked about it, and then realized, not only did it already exist, but I already read about it and just forgot the name.