Ha, this one hits home 😅

Our Outpost front-end already reads five container systems — Snaps, Threads,
Waves, Hangs and D.Buzz — all reverse-engineered straight off the chain, exactly
like you describe. And then last week we cheerfully added two more undeclared
ones of our own (BBH Chats and Alive Pings). So yeah, we're both halves of your
problem 🤣

The reason I'm interested: it's one codebase serving two tribes (BBH and Alive),
config-only per tribe. So whatever we declare lands on both at once, and on every
tribe that comes after. Just made "read another tribe's feed" a one-line setting
this week — no code, no new container, nothing posted into anyone else's account.

Will register our attributes. container: true is already in there; the
short-form posts themselves are the gap, they carry nothing that says what they
are.
And am seeing the same error on your site as mentioned before here in the comments...

!ALIVE !BBH !MMB !INDEED