Sub-project 2 of the mesh-hardening follow-on (the post-incident roadmap
ordering puts ubongo first). Harden the control node's inbound surface via
base's nftables firewall as INPUT-only default-deny: the forward chain stays
permissive (new base__firewall_input_only knob) so Docker egress + the
libvirt-NAT integration harness keep working, and there is no sshd ListenAddress
change — sidestepping the ip_nonlocal_bind boot-race that sank askari. SSH
allowed from wt0, ssh-from-control (Ansible self), and mamba on the LAN (new
base__firewall_admin_addrs). Harness-validated before an operator-supervised
cutover; the physical console is the permanent break-glass.
Design maps to the four relevant 2026-06-17 incident lessons (FRICTION signals
1/2/3/6).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
