Make iterating on a Firecracker-friendly Void guest practical without replacing the Debian default image path.
Add local Void rootfs build/register/verify plumbing, a language-agnostic dev package baseline, and guest SSH/work-disk hardening so new images use the runtime bundle key, keep a normal root bash environment, and repair stale nested /root layouts on restart.
Replace the guest PING/PONG responder with an HTTP /healthz agent over vsock, rename the runtime bundle and config surface from ping helper to agent while still accepting the legacy keys, and route the post-SSH reminder through the new vm.health path.
Validated with GOCACHE=/tmp/banger-gocache go test ./..., make build, bash -n customize.sh make-rootfs-void.sh, and git diff --check.
Remind users when a VM is still running after hanger vm ssh exits instead of silently dropping them back to the host shell.\n\nAttach a Firecracker vsock device to each VM, persist the host vsock path/CID,\nadd a new guest-side banger-vsock-pingd responder to the runtime bundle and both\nimage-build paths, and expose a vm.ping RPC that the CLI and TUI call after SSH\nreturns. Doctor and start/build preflight now validate the helper plus\n/dev/vhost-vsock so the feature fails early and clearly.\n\nValidated with go mod tidy, bash -n customize.sh, git diff --check, make build,\nand GOCACHE=/tmp/banger-gocache go test ./... outside the sandbox because the\ndaemon tests need real Unix/UDP sockets. Rebuild the image/rootfs used for new\nVMs so the guest ping service is present.
Reduce the control plane's dependency on helper scripts while keeping the hard Linux integration points in the approved shell-out layer.
Replace the bash-driven image build path with a native Go builder that clones and optionally resizes the rootfs, boots a temporary Firecracker VM, provisions the guest over SSH, installs packages and modules, and preserves the package-manifest sidecar.
Also replace a few small convenience shell-outs with Go helpers: read process stats from /proc, use os.Truncate for ext4 image growth, add file-clone and normalized-line helpers, drop the sh -c work-disk flattening path, and launch Firecracker via a direct sudo command.
Add tests for the new SSH/archive and system helpers, plus a policy test that keeps os/exec imports confined to cli/firecracker/system. Update the docs to describe customize.sh as a manual helper rather than the daemon's image-build backend.
Validated with go mod tidy, go test ./..., and make build.
