feat(prod): observability for the two failure modes that went unseen, plus OIDC self-healing

Minimal prod delivery, authored directly on main (= prod's live revision d1a6628)
rather than by merging work/prod-standup-campaign. That branch carries the DNS apex
inversion, which would have set prod's BASE_DOMAIN to home.keithjackson.dev; prod
runs external-dns with policy: sync and txtOwnerId: prod, so it would have begun
rewriting apex records dev owns while the non-k3s prod still serves 443 there.
Operator sequencing is "dev migrates first". Nothing under clusters/ is touched
here at all, which is what makes this safe to land now.

Also deliberately EXCLUDED, because prod's live cluster-vars has no CNPG_BACKUP_PATH
key and StrictPostBuildSubstitutions would fail the whole tier: the R2 rework of
platform/velero/ and the CNPG destinationPath changes. Those land as
feat/r2-backup-prod together with the endpoint and bucket knobs.

WHAT THIS FIXES

1. Nothing was watching CNPG. All three prod databases have run since bootstrap with
   ContinuousArchiving=False and firstRecoverabilityPoint=null, and no alert existed
   anywhere. Because archive_mode=on and the archive command fails, Postgres refuses
   to recycle WAL: keycloak-db holds every segment ever written (257 MiB on a 5 GiB
   volume, ~6.8 MiB/h) — roughly 29 days to a disk-full PANIC on the cluster's SSO
   database. Found by hand, 38h late. CNPGWALArchiveBacklog would have fired within
   the hour, and evaluates to 3 firing series on prod today.
   Rules key on cnpg_collector_* rather than cnpg_pg_stat_archiver_*, because
   nextcloud-db's exporter cannot log in to its own database (permission denied for
   database "nextcloud", both clusters) so the pg_stat_archiver family does not exist
   for it — the obvious metric would have been blind to one database in three.

2. No PVC outside namespace=monitoring had any fill alert. New rules are partitioned
   by namespace so they cannot double-fire with MonitoringVolumeFillingUp, pinned to
   job="kubelet" (the apiserver copy of the same series reports namespace=default),
   and guarded by inodes > 0 — block-mode PVCs such as unifi-rootdisk report
   available=0 forever and would otherwise have fired critical permanently.

3. VPNTunnelDown could never clear on a cluster with no gateway node; it has been
   firing critical on prod since 2026-09-05. Now guarded so prod self-arms the moment
   a node carries the egress-gateway label, with dev's behaviour unchanged today.

4. The Keycloak realm import fails OPEN: an unresolved placeholder is stored
   LITERALLY and the import still reports success, then sits at Done=True and never
   re-runs. On 2026-09-06 all 12 prod OIDC clients held the literal
   $(env:..._CLIENT_SECRET) string and every SSO login failed, while every signal was
   green. The CronJob is the level-triggered correction; two alerts make its silence
   observable. Repaired live already — this stops it recurring.

Also: the R-NET-04 conformance scan descended into nested agent worktrees under
.claude/, counting 4 egress policies where 1 is authored.

Co-Authored-By: Claude Opus 5 <[email protected]>

conformance/tests/README.md

@@ -93,9 +93,52 @@ and coverage extraction exact and robust.
   break the thing and assert fail-closed / no-data-loss, with `finally` restoring state.
 - **Never weaken a test to go green (R-TEST-06).** If the spec can't be met, escalate to
   the PM — do not relax the assertion or the requirement.
+- **Never write a per-environment value into a test (R-ENV-02).** No hostname suffix, no
+  Gateway VIP, no LB-pool range. One authored suite must run green against dev *and* prod,
+  so a test **asks the cluster it is pointed at** what it is. The mechanism is a chainsaw
+  binding over the same ConfigMap Flux substitutes from:
+
+  ```yaml
+  spec:
+    bindings:
+      - name: baseDomain
+        value: (x_k8s_get($client, 'v1', 'ConfigMap', 'flux-system', 'cluster-vars').data.BASE_DOMAIN)
+  ```
+
+  Declare it at **test level** (step `outputs`/`bindings` are step-scoped), then consume it:
+  `($baseDomain)` for a pod `env:` value, `(join('.', ['myhost', $baseDomain]))` where a
+  full hostname is needed — including inside a `fixtures/*.yaml` applied with `apply: file:`,
+  which chainsaw templates with the same bindings. Prefer reading the *actual* observed value
+  over restating a range (e.g. assert the DNS answer equals `GATEWAY_VIP`, or equals the LB IP
+  the Service was assigned) — it is both stricter and environment-independent. Never take the
+  environment from a CLI flag or an exported variable: a flag someone forgets is how a suite
+  ends up silently asserting the other cluster's expectations. L1 goldens are the one
+  exception: they are rendering fixtures and carry the literal `${BASE_DOMAIN}` token.
+
+### How a scaffold declares itself (and how `status.py` tells one from a verifier)
 
 Scaffolds in this tree carry `TODO(T-x.y)` markers where a fixture/assertion lands as a
-later roadmap phase delivers the capability under test. `lib/status.py` treats such a
-marker — in the `chainsaw-test.yaml`, in `render-check.sh`, or in `check.sh` — as
-outranking any `conformance.home.k3s/executable: "true"` annotation, so a placeholder body
-can never be reported as an executable test.
+later roadmap phase delivers the capability under test. `lib/status.py` classifies each
+test EXECUTABLE or SCAFFOLD from the test's own files — `chainsaw-test.yaml`,
+`render-check.sh`, `check.sh` — and either signal below **outranks**
+`conformance.home.k3s/executable: "true"`, so a placeholder body can never be reported as
+an executable test. Declare a scaffold in **both** positions:
+
+1. **`# STATUS: scaffold — <what is missing>`** in the file's header comment block. The
+   declared state must be the first token after `STATUS:` (executable tests say
+   `# STATUS: EXECUTABLE` / `IMPLEMENTED` / `RUNNABLE`).
+2. **A `TODO`/`FIXME` marker carrying a message, in the body** — the file from its first
+   non-comment line onward. `echo "TODO(T-4.2): inject a fault to fire a rule"`,
+   or an inline comment on a missing fixture:
+   `file: fixtures/smtp-sink.yaml   # TODO(T-4.1): hermetic SMTP capture sink`.
+
+What is **not** a scaffold marker, and why the distinction is load-bearing: a marker
+mentioned in the **header prose** (the Given/When/Then and the mandatory "what this does
+NOT prove" list), and a marker that is the **entire content of a quoted literal** — a
+placeholder *detector*'s own vocabulary, e.g. `SEED = ["TBD", "TODO", "FIXME", ...]` in
+`l0-static/placeholder-guard-coupling/check.sh`. A whole-file `"TODO" in text` test used to
+classify that 32-assertion check as a scaffold and, through it, report the safety-critical
+R-STATE-03 as `exec=1 scaffold=1`. If your check must hold a marker as data, keep each
+idiom a **standalone quoted literal in a list**; a marker with text attached (a regex
+alternation, several idioms in one string) still classifies as a scaffold, because
+ambiguity here only ever downgrades.