Runtime Model

Durable state lives under:

~/.local/state/hb

The current runtime model is:

• the builder container is generation-aware
• helper scripts are rewritten declaratively on activation
• the user-side SSH path wakes the builder on demand with ProxyCommand
• the root nix-daemon path can use the localhost bridge when enabled
• idle shutdown runs inside the guest and stops sshd after inactivity

The builder uses the image’s built-in /nix directly. Build outputs live in the container’s writable layer, so recreating the container loses any guest local store writes that were not already available from substituters.

That design keeps the module simpler than the older overlay-based approach, but it also means the builder should be treated as a cache-backed disposable guest, not as a durable Linux machine image.