feat(dns): INVERT to operator's simpler layout — dev to subdomain, prod to apex

*** DO NOT MERGE TO main WHILE THE OPERATOR IS AWAY. MERGING IS THE MIGRATION. ***

Operator simplified the architecture, inverting c8c1d29:
  dev  -> *.dev.home.keithjackson.dev        (was the apex)
  prod -> *.home.keithjackson.dev            (the apex; no prod. subdomain, no CNAME layer)

WHY MERGING IS DANGEROUS, and this is the finding that matters most here:
clusters/dev/sync.yaml self-reconciles ./clusters/dev from `main` every 10 minutes. Merging
these files EXECUTES the cutover on the live dev cluster, unattended. And because the same
commit moves dev's GitRepository url to gitea.dev.home.keithjackson.dev, dev STRANDS — it
stops reconciling and cannot be fixed by pushing, because the broken thing IS the path Flux
reads pushes through. Banners added at the top of clusters/dev/kustomization.yaml and beside
the url itself. That url cannot be tokenized: the root Kustomization declares no
substituteFrom, so `gitea.${BASE_DOMAIN}` would ship the literal token.

Verified dev is currently safe: this work is NOT on origin/main, dev is reconciling
main@4809199, and its live BASE_DOMAIN is still home.keithjackson.dev. Deliberately NOT
pushed to the bootstrap Gitea either — prod reconciles from there, and prod on `prod.home.`
cannot collide with dev on the apex, so that is the safer interim for prod.

VALUES
                BASE_DOMAIN                  TXT_OWNER_ID   DOMAIN_FILTER
  base          dev.home.keithjackson.dev    sentinel       keithjackson.dev
  dev           dev.home.keithjackson.dev    dev            keithjackson.dev
  prod          home.keithjackson.dev        prod           keithjackson.dev
Ansible seam inverted too: role default k3s_base_domain = dev's subdomain, group_vars/k3s_prod
overrides to the apex.

dev's txtOwnerId moves `default` -> `dev`. The old value was FORCED (its live apex records
were already registered under `default`, so renaming would have orphaned them). On a new
suffix dev publishes a brand-new record set with no prior registry, so the id is chosen on
merits — and `default` has none: it is what you get by FORGETTING the flag, which is exactly
how both clusters came to share it and delete each other's records. Operationally it also
means dev's old apex records stay owned by a now-unclaimed id, so nothing deletes them
implicitly and vacating the apex becomes an explicit sequenceable step rather than a race
between two reconcile loops. PROD MUST NEVER BE GIVEN `default`: prod inherits the apex
NAMES, so `default` is the one value that would let it adopt and policy:sync-delete dev's
still-live apex records — the same incident with the roles swapped.

DOMAIN_FILTER stays the ZONE for both, with F-DNS1 written into all three files as a
do-not-retry: a subdomain filter drops the parent zone and publishes NOTHING.

VERIFICATION — the property changed, and so did the method. "Dev renders byte-identically" no
longer applies because dev is deliberately migrating. Instead: apply the INVERSE substitution
to the new render and demand byte-identity with the baseline. 145 changed line pairs, every
one classified: 143 hostname-move, 2 declared owner-id, ZERO unexplained, ZERO bare-apex
remnants. cilium and velero show 0 changes and provably contain no hostname, so they are not
blind spots. Prod: 0 occurrences of prod.home., 0 of dev.home., 143 apex names. Certs: dev
*.dev.home.keithjackson.dev, prod *.home.keithjackson.dev.

THREE positive controls, all fire — including one that proves the two checks are not
redundant: injecting a single un-moved hostname SURVIVES the inverse-substitution check and is
caught only by the independent bare-apex scan. That is why both exist.

Ansible probe (connection: local, zero SSH): dev nodes -> keycloak.dev.home..., prod nodes ->
keycloak.home.... Used roles: + --tags probe rather than include_vars, because include_vars
outranks group_vars and would have FALSELY shown prod inheriting dev's value.

Gates all PASS: l0, l1, render-golden (10 goldens), lint, substitution (254 assertions),
render.py --selftest, spec-immutability. Catalog ServiceDefinitions edited, never rendered apps/.

RUNBOOK rewritten in §10 + §10a with the ordering that avoids stranding: D0 snapshot escape
routes -> D1 break the automatic trigger -> D2 publish and PROVE gitea.dev.home + the new
wildcard cert WHILE dev still serves the apex -> D3 merge -> D4 release reconciliation
deliberately -> D5 Keycloak issuer + ~12 clients (headlamp's is SOPS, by hand) -> D6
one-server-at-a-time k3s restart + SSO re-issue (service restart only, NO reboots) -> D7
retire old apex records -> D8 verify the apex is empty AGAINST CLOUDFLARE, not pfSense —
the gate on everything after. Then P1 unsuspend prod.

ACME: prod's wildcard is EXACTLY the name set dev holds today, so prod's orders share dev's
5-per-week duplicate-certificate bucket. Order after D8, delete dev's old Certificate rather
than let it renew, rehearse on staging.

The 6 L2 chainsaw tests hardcoding the apex are enumerated but deliberately NOT edited — while
dev is live on the apex they are correct; they need per-environment parameterisation.

Serves: R-ENV-02, R-DNS-01/02/03, R-TLS-01.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

clusters/prod/kustomization.yaml

@@ -129,14 +129,23 @@ patches:
   #
   # WHY THE IN-CLUSTER URL CANNOT BE USED YET (blocker found 2026-09-01, still true; the
   # unusable value was `https://gitea.home.keithjackson.dev/Home-Network/home-network-k3s-impl.git`).
-  # Two independent reasons, both consequences of the split-horizon design:
-  #   1. SELF-HOSTING CIRCULARITY. Gitea runs ON THE DEV CLUSTER. Prod syncing from it means prod's
-  #      GitOps source lives inside the very cluster slated for decommission. Gitea must move to
-  #      prod (or off-cluster) BEFORE dev is retired, or prod loses its source of truth.
-  #   2. SPLIT-HORIZON DNS SENDS IT TO THE WRONG PLACE. platform/coredns/coredns-custom.yaml
-  #      answers the ENTIRE home.keithjackson.dev zone with ${GATEWAY_VIP}. On prod that is
-  #      192.168.2.20 — PROD's own gateway, where no Gitea is listening. Prod's Flux would resolve
-  #      gitea.home.keithjackson.dev to itself and never reach a repository.
+  # REASONING UPDATED 2026-09-04 for the new suffix direction (prod = the apex, dev = dev.home.),
+  # which changes WHY the blocker holds but not THAT it holds:
+  #   1. SELF-HOSTING CIRCULARITY — still true, and now the only reason. The Gitea this repo is
+  #      pushed to runs ON THE DEV CLUSTER. Prod syncing from it would put prod's GitOps source
+  #      inside the very cluster slated for decommission. Gitea must move to prod (or off-cluster)
+  #      BEFORE dev is retired, or prod loses its source of truth.
+  #      NOTE the suffix change makes the two Giteas DIFFERENT HOSTS: dev's is now
+  #      gitea.dev.home.keithjackson.dev and prod's is gitea.home.keithjackson.dev. Prod pointing at
+  #      the apex name therefore means "prod's OWN Gitea", never dev's — which is what makes the
+  #      cutover below a one-line change once prod actually runs Gitea.
+  #   2. SPLIT-HORIZON DNS — NO LONGER A BLOCKER, and the note is kept because the old reasoning is
+  #      easy to re-derive incorrectly. platform/coredns/coredns-custom.yaml answers the whole
+  #      ${BASE_DOMAIN} zone with ${GATEWAY_VIP}; when prod's BASE_DOMAIN was `prod.home.` that meant
+  #      prod resolved gitea.home.keithjackson.dev to PROD's gateway (192.168.2.20) where no Gitea
+  #      listened — a misdirection. Now that prod IS the apex, resolving gitea.home.keithjackson.dev
+  #      to prod's own Gateway is CORRECT: that is where prod's Gitea will be served from. What
+  #      remains is purely reason 1 — the Gitea is not there YET.
   #
   # WHAT THE TEMPORARY SOURCE IS (stood up 2026-09-04 on explicit operator direction):
   #   bootstrap/gitea/bootstrap-gitea.sh with HOST_NAT_IP=192.168.2.132 — a podman container on the
@@ -202,28 +211,41 @@ patches:
         path: /data/ACME_CLUSTER_ISSUER
         value: "letsencrypt-prod"
       # ==========================================================================================
-      # PROD DNS IDENTITY (R-DNS-01/02/03) — the fix for the 2026-09-04 incident.
+      # PROD DNS IDENTITY (R-DNS-01/02/03) — PROD **IS** THE APEX.
       # ==========================================================================================
-      # PROD SERVES ITS OWN SUBDOMAIN. Until 2026-09-04 every hostname was HARDCODED to
-      # home.keithjackson.dev in the base manifests, so prod was authored to serve the EXACT SAME
-      # public names as the live dev cluster out of the SAME Cloudflare zone. Two consequences, one
-      # of which already happened:
+      # OPERATOR DECISION 2026-09-04, superseding the interim split committed earlier the same day
+      # (prod on `prod.home.` behind apex CNAMEs). The simpler target, and the one authored here:
+      #
+      #   dev   -> dev.home.keithjackson.dev     (dev carries the label; clusters/dev)
+      #   prod  -> home.keithjackson.dev         (THE APEX — this knob)
+      #
+      # There is NO `prod.` label and NO CNAME layer. `<svc>.home.keithjackson.dev` is prod's REAL
+      # name, so nothing has to alias anything: prod's Gitea is gitea.home.keithjackson.dev, its
+      # Keycloak keycloak.home.keithjackson.dev, and the wildcard cert is `*.home.keithjackson.dev`.
+      #
+      # BACKGROUND — WHY THE SUFFIXES HAD TO SPLIT AT ALL. Until 2026-09-04 every hostname was
+      # HARDCODED to home.keithjackson.dev in the base manifests, so prod was authored to serve the
+      # EXACT SAME public names as the live dev cluster out of the SAME Cloudflare zone. Two
+      # consequences, one of which already happened:
       #   1. HAPPENED: prod's external-dns (policy: sync, owner id `default` — the same implicit
       #      default dev had) concluded it owned dev's records and DELETED EVERY ONE of them.
       #   2. QUEUED BEHIND IT: platform-config would have requested a `*.home.keithjackson.dev`
       #      wildcard from letsencrypt-prod for a cert dev already holds, and both clusters would
       #      have raced each other's `_acme-challenge` TXT records on that one zone.
-      # Moving prod to its own suffix dissolves both: the two clusters can no longer name the same
-      # record. This is what makes ACME_CLUSTER_ISSUER: letsencrypt-prod above safe here.
       #
-      #   dev   -> home.keithjackson.dev         (UNCHANGED — dev is live; phase 2 moves it)
-      #   prod  -> prod.home.keithjackson.dev    (this knob)
-      #
-      # CONSEQUENCE — prod's hostnames are NOT the apex names. Prod's Gitea is
-      # gitea.prod.home.keithjackson.dev, its Keycloak keycloak.prod.home.keithjackson.dev, and so
-      # on; the wildcard cert becomes `*.prod.home.keithjackson.dev`. The apex CNAMEs that make
-      # `<svc>.home.keithjackson.dev` point at prod are PHASE 2, deliberately not done here — they
-      # would take traffic off the live dev cluster. infra/PROD-PROVISIONING.md §10.
+      # *** THE ORDERING CONSTRAINT THIS VALUE CREATES — READ BEFORE UNSUSPENDING ANYTHING. ***
+      # Prod now claims the very names the LIVE dev cluster is serving today. Both hazards above are
+      # therefore still armed until DEV HAS VACATED THE APEX. Prod's `platform` and its 10 downstream
+      # tiers are SUSPENDED for exactly this reason. The gate is not "review is done", it is:
+      #   (a) dev is reconciling on *.dev.home.keithjackson.dev with a Ready wildcard cert, AND
+      #   (b) dev's old apex A/CNAME records and their TXT registry entries are GONE from Cloudflare
+      #       (verified against Cloudflare directly — a pfSense override is NOT evidence about public
+      #       DNS; that mistake was made on 2026-09-04), AND
+      #   (c) dev's old `*.home.keithjackson.dev` cert/Certificate is released, because prod ordering
+      #       that same name set while dev's still exists counts against LE's duplicate-certificate
+      #       limit (5 per week per identical name set).
+      # Full ordered runbook: infra/PROD-PROVISIONING.md §10. Unsuspending before (a)-(c) re-creates
+      # the 2026-09-04 incident with the roles reversed.
       #
       # [parity] MUST equal k3s_base_domain in infra/ansible/inventory/group_vars/k3s_prod/vars.yml.
       # The kube-apiserver's oidc-issuer-url is an INSTALL-TIME k3s flag, not a manifest, so it is
@@ -231,30 +253,33 @@ patches:
       # trusts a different Keycloak than the one prod actually runs.
       - op: replace
         path: /data/BASE_DOMAIN
-        value: "prod.home.keithjackson.dev"
-      # SAFETY NET #2 (independent of the owner id below): narrow ExternalDNS's name scope to prod's
-      # OWN subtree, so prod cannot create, update or delete any record outside it no matter what the
-      # TXT registry says. VERIFY ON FIRST RECONCILE — the Cloudflare provider uses this value for
-      # ZONE selection too, and on the version in use in 2026-08 a strict-subdomain filter dropped
-      # the parent zone ("no hosted zone matching record DNS Name"). If prod's external-dns logs no
-      # matching zone, it will create NOTHING — fail-closed, and it can still never delete dev's
-      # records. Fallback in that case: set this to "keithjackson.dev" (dev's value) and rely on
-      # EXTERNALDNS_TXT_OWNER_ID below, which is sufficient on its own.
+        value: "home.keithjackson.dev"
       - op: replace
         path: /data/EXTERNALDNS_DOMAIN_FILTER
-        # MUST be the Cloudflare ZONE, not prod's subdomain. FINDING F-DNS1 (DECISIONS-LOG,
-        # 2026-08-17) proved a subdomain filter DROPS THE PARENT ZONE: ExternalDNS generated the
-        # record then skipped it with "no hosted zone matching record DNS Name", so prod would
-        # publish NOTHING. Isolation from dev does NOT come from this filter — it comes from
-        # (1) prod only requesting *.prod.home.keithjackson.dev hostnames, and
-        # (2) txtOwnerId: prod, so prod's registry never claims dev's `default`-owned records.
+        # MUST be the Cloudflare ZONE. Prod now serves the apex, so `home.keithjackson.dev` looks
+        # like a tighter, more honest filter than the zone — IT IS NOT, IT IS AN OUTAGE. FINDING
+        # F-DNS1 (DECISIONS-LOG 2026-08-17) proved a STRICT SUBDOMAIN of the hosted zone drops the
+        # zone entirely: ExternalDNS generates the record then skips it with "no hosted zone matching
+        # record DNS Name", so prod publishes NOTHING. An agent narrowed this to
+        # prod.home.keithjackson.dev on 2026-09-04 and it was reverted in review; do not retry it.
+        # Isolation from dev does NOT come from this filter — it comes from
+        # (1) the two clusters requesting DISJOINT hostname sets (apex vs dev.home.), and
+        # (2) txtOwnerId: prod vs dev, so neither registry ever claims the other's records.
         # That pairing is what the 2026-09-04 incident needed and this filter cannot provide.
         value: "keithjackson.dev"
       # SAFETY NET #1 — THE ACTUAL ROOT CAUSE OF THE INCIDENT. Both clusters left this unset and so
       # both inherited the chart default `default`; prod then treated dev's TXT-registry entries as
-      # its own and, under policy: sync, deleted the records behind them. This value MUST differ from
-      # dev's (`default`, pinned in clusters/dev — dev's live records are registered under it and
-      # cannot be renamed without orphaning them). `prod` is distinct, which is the entire fix.
+      # its own and, under policy: sync, deleted the records behind them.
+      #
+      # PROD MUST NOT BE GIVEN `default`, however tempting it now looks. Prod is taking over the apex
+      # NAMES, and dev's existing apex records are registered under owner `default` — so `default` is
+      # the one value that would let prod adopt them. It would also let prod SYNC-DELETE the ones no
+      # prod source claims, on a cluster dev is still serving. Prod inherits the apex names; it must
+      # never inherit the apex OWNER ID. `prod` keeps prod fail-safe: records owned by `default` are
+      # invisible to it, so an early unsuspend cannot destroy dev's DNS the way 2026-09-04 did — it
+      # simply fails to publish until those records are retired, which is the correct behaviour.
+      # dev is `dev` (clusters/dev, changed with dev's migration); the base default is a
+      # non-colliding sentinel. All three differ.
       - op: replace
         path: /data/EXTERNALDNS_TXT_OWNER_ID
         value: "prod"