D-125: Model B per-DC ISP egress (bridge-in, single-NAT) -- resolves OBS-3 design gap ...

OBS-3: Model B nesting put vr1-dc0-wan (a libvirt NAT) inside vvr1-dc0, whose
only leg is the SEC-010 FORWARD-dropped transit -- so the per-DC simulated ISP
had no egress. Operator ruled bridge-in (single-NAT) over double-NAT.

- modules/wan-bridge (NEW): libvirt forward=bridge onto a pre-existing host
  bridge (bridge={name}, schema measured from the provider, not guessed). No
  subnet/NAT. Sibling to site-wan so every NAT user stays untouched. Covered by
  opentofu-validate S3 (standalone PASS).
- OUTER root: vcloud ISP NAT vr1_dc0_uplink (the single NAT) + a 2nd IP-less
  uplink NIC on vvr1-dc0 + the br-vr1-dc0-wan bridge declared in netplan (transit
  stays NIC1 so SEC-010/--transit-if keep keying on it). New HELD var
  vr1_dc0_uplink_cidr (no default; office1-netbox apex, hard rule 2).
- INNER root: vr1_dc0_wan site-wan(NAT) -> wan-bridge onto br-vr1-dc0-wan;
  OPNsense WAN re-addresses into the vcloud ISP /24 (edge config, D-113, HELD).
- Bootstrap (site-headend-install.sh): --uplink-if/--wan-bridge; --check verifies
  the bridge exists + uplink ENSLAVED (fail-open guard, same class as the transit
  check); SEC-010 rationale corrected (bridge-in has no inner NAT) + br_netfilter
  CONSTRAINT (keep the FORWARD-drop interface-scoped, NEVER global). Harness 49->54.

Records: D-125 (new); D-122 amendment (forward-pointer -- WAN realization
superseded, intent stands); SEC-010 (br_netfilter + hardened --check);
model-a-fallback B->A delta item 8 + revert; platform-traps 1g (bridge +
br_netfilter + nested-foreign-MAC trap).

NOT closed: the L2-NAT-of-foreign-MAC path is a DEPLOY-TIME gate (bridge-in
equivalent of the depth-4 boot gate); fallback = double-NAT. HELD: vr1_dc0_uplink_cidr
+ OPNsense WAN re-address. Both roots validate; gauntlet ALL GREEN (63); repo-lint
0 fail. Present-only; NOT pushed.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ck6xh3jWQi5b3Su8Dx1LEH

Stage-3 review sweep C+D: Model B two-root reshape + SEC-010 hardening ...

Phase C (Model B reshape, D-123 operator ruling):
- outer root (opentofu/main.tf): vvr1-dc0 resized to whole-DC containment VM
  (108 vCPU / 425984 MiB / 3221225472000 bytes; expose_nested_virt=true;
  single Office1 transit leg); node/plane/wan/opnsense modules removed from
  vcloud level (MOVED markers), storage-04 added per R-3.
- inner root (opentofu/vr1-dc0-substrate/): NEW second root, provider
  qemu+ssh to vvr1-dc0; reuses ../modules/* verbatim to build 9 nodes +
  6 planes + wan + opnsense inside the containment VM. dmacvicar/libvirt
  0.9.8 pinned (.terraform.lock.hcl committed). Both roots tofu-validate.
- variables.tf: vvr1_dc0_vcpu/memory_mib/disk_bytes with derivation comment.

Phase D (SEC-010, R3-F02): site-headend-install.sh --host-nodes node-host
bootstrap installs qemu-kvm+libvirt, persists+verifies nested=1, writes a
transit FORWARD-drop (nftables inet sec010) enforcing DC-LOCAL under Model B.
Gate hardened (advisor catch): --check now verifies the keyed transit
interface EXISTS, else nftables oifname loads clean but matches nothing
(fail-open). Harness 49/49.

Records: D-103/107/114/121/122/123/124 amendments (append-only);
model-a-fallback-plan synced; ledgers + Phase-C changelog.

KNOWN GAP (OBS-3, operator-confirmed 2026-07-16): under Model B the inner
vr1-dc0-wan NAT is nested inside vvr1-dc0 (single transit NIC), severing the
simulated-ISP egress that Model A had at vcloud level. DC0/DC1 ARE meant to
have ISP connections -- egress path resolution is follow-up design work, not
resolved by this commit.

Present-only; not pushed. Gauntlet ALL GREEN (63); repo-lint 0 fail.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ck6xh3jWQi5b3Su8Dx1LEH