Whether the node is ready to serve extension traffic.

There is a window in which an extension endpoint exists but its tables do not. The dispatch tree is compiled during Nova's boot, inside nova_sup:init/1; kura_migrator:migrate/1 runs later, from asobi_app:start/2. Anything listening in between would reach a handler whose tables have not been created.

So core signals readiness once, after migrations, and the seam below fails closed until then.

The seam

guard/0 is what the RPC dispatcher calls before dispatching:

case asobi_readiness:guard() of
    ok -> dispatch(Method, Params);
    {error, Object} -> {asobi_error, 503, Object}
end.

The dispatcher itself is Wave 2b and does not exist yet. guard/0 and the not_ready code do, and they are tested, so the dispatcher inherits a readiness contract rather than inventing one.

persistent_term rather than a process: the read is on the dispatch path, it happens once per call, and the value is written exactly once at boot.

The other reader

asobi_extension_sup reads ready/0 at init/1. Migrations run before asobi_sup:start_link/0, so the answer is already final by then, which is what lets an extension's own sup/0 children query at init/1 without a retry path: either the database is there, or no extension started at all.