Replies go through the RPC exchange keyed by the caller's reply-queue name, not
the default exchange — so a serving module's scoped account answers with write
on mesh.rpc alone, never the default exchange (which would let it publish into
any queue). 'mesh-tools invoke <module> <tool> [args]' is the caller's side, the
sibling of emit. Verified against a real broker: a scoped account serves its
tool and is refused another module's serve queue.
jschoubben
4558248f16