Stage 4 cleanup: carve residue 108 fabrics -> 17; dc1 leftover nginx purged ...

Both items were queued to the stage close at the 2026-07-23 carve.

CARVE RESIDUE. Deleted subnet id=8 192.168.1.0/24 (the superseded OPNsense FACTORY LAN -- both
edges were long since re-addressed to 10.12.4.1 / 10.12.64.1), then fabric-5, then the 90
auto-created empties (ids 6..95). 108 fabrics -> 17.

The audit caught an ORDERING DEPENDENCY the original flag did not state: 192.168.1.0/24 was the
ONLY occupant of fabric-5, so deleting the fabric first would have cascaded the subnet away
instead of removing it cleanly. Subnet first, then the fabric.

METHOD, chosen because of this repo's own history: a MAAS fabric delete cascades to its VLANs,
and the 2026-07-21 pod-delete incident cost 9 machine records precisely because the association
check ran AFTER the delete. So emptiness was PROVEN per fabric -- zero subnets, zero ipranges,
zero node interfaces across all its VLANs -- against a fresh occupancy snapshot (fabrics +
subnets + ipranges + every machine's interface_set) taken immediately before the batch, and the
cascade check was re-run afterwards too.

KEPT, all verified occupied: office1 base + GUA (fabric-0), office1 compose with its 2 LXD
guests (fabric-1), both transits (fabric-2 / fabric-141), both metal-admin/boot fabrics with 9
nodes each (fabric-4 / fabric-142), libvirt default (fabric-3), and the 10 named plane fabrics.

POST-STATE: 18 Ready + 2 Deployed office1 guests, all 18 still power_type=virsh, 7 interfaces
each (6 flat planes per D-133 + br-ex), ZERO orphaned interfaces, placement tags 9+9 intact,
both DCs' artifact paths re-verified PASS.

NGINX ON dc1. Purged nginx + nginx-common (dry-run first: nothing else depended on them, no
nginx-core was installed), plus autoremove of liblockfile-simple-perl and liblog-agent-perl --
debmirror's orphaned perl deps. /etc/nginx gone, nothing on :80, proxy still PASS on :3142. dc0
keeps its nginx and was re-verified unaffected (it serves the mirror).

Capture docs/audit/stage4-carve-residue-cleanup-20260727.txt. repo-lint 0-fail.

Revert: fabrics/subnets are MAAS records, not config -- no undo, and nothing needs them (90
were auto-created empties; 192.168.1.0/24 was a superseded factory address). nginx reverts with
apt-get install nginx, which dc1 has no use for while it is the proxy DC.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HvCyrwvYTTcDYnRErfMsNf