- cargo.build (native): one source copy, tests under WASI, release
build to /state/cargo/builds/<n>/, process groups killed on cancel.
The host writes the SDK copy to /plugins/cargo/sdk/ at start.
- sausage test-runner: one instance per test, in parallel, with its own
mount table (empty world, package folder at its path); answers
core.lock, core.unlock, core.notify, core.log.
- The console: rustyline, notifications while typing, ls/cat through the
process view, methods, ps, log, activate, revert, stop, kill.
- core.notify on stdout is handled in order, before the response.
