Upgrades retire old processes after a grace period, then call
rpc.retired. Services live in boot.json. One preopen / with a mount
table in the sausage-vfs crate, with guards for in-flight file
operations. Draft 7 and our own compatibility check on a fixed subset.
Imports register with inventory. Rules for liveness, stop states,
routing, locks, activation, endpoints (rpc.endpoint handshake), boot,
builds, and a 10 ms scheduling tick.
The design from the redesign discussion: a process per call, JSON-RPC on
stdin and stdout, a virtual /proc, /self, and /run, TCP endpoints, locks,
a central journal, generated imports with interface checks at activation,
and the SDK with examples.