As someone who's built a forum software for 10+ years (NodeBB), I'm glad you found the experience exciting.

I find building out forums exceedingly fun too (which is why I've been at it for a decade). Like you, we realized that federation between forums is quite important from a communication POV, though I'm not sure if you went that direction or just used PDSes as your user store.

We ended up integrating ActivityPub and its really reinvigorated my passion for building forums again :)

Usually when someone on HN talks about building a forum out, I tell them it took me a year (3 devs) before we reached rough feature parity. Perhaps it's possible for AI assisted clones to reach this point in weeks or months rather than years.

Good luck! When you get tired of it, just tell your agent to migrate all your data to NodeBB.