Two optional, server-class keys in the box.env allowlist. BOX_REQUIRE_VM=1
refuses both the silent container fallback (no /dev/kvm, exit 1) and an
explicit --container (exit 2): such a template's trust boundary is the VM,
and its guest runs docker. BOX_AUTOSTART=1 stamps boot.autostart=true at
launch, per-instance like limits.*, so the box comes back deterministically
after a host reboot; a --from clone needs no code because 'incus copy'
keeps every non-volatile config key — the same ride the user.* stamps take.
Still no key for a network or a security flag, on purpose.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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