docs(keycloak): record the URL-reconciliation decisions

Records K1-K9: extend-vs-sibling and why, the generated+gated desired state, verbatim
token pass-through, per-pass fail-closed, order-insensitivity, unmanaged-means-untouched,
public clients' URLs managed, one alert pair not two, and the mutation harness.

Also records a process note: my first pass reported three false findings (reconciler
absent from main, import not templated, BASE_DOMAIN dead) because I diffed against
origin/main -- origin is dev's Gitea, stale at 4809199, while the live remote is
prod-gitea at fa4deac. All three were wrong. The rule for this repo is written down so
the next agent does not repeat it: origin is not the source of truth.

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

DECISIONS-LOG.md

@@ -2331,3 +2331,95 @@ vpn-class egress dead until someone noticed.
    > gateway whose tunnel interface is dynamic requires an explicit re-resolution trigger on every
    > interface change. This is a standing operational requirement of the ADR-0015 design, not an
    > implementation detail.*
+
+## Keycloak client REDIRECT URIs reconcile too — the same one-shot, one field over (2026-09-12)
+
+Follow-up to the client-secret reconciler. That CronJob heals the one field the one-shot realm
+import got wrong in the 2026-09-06 outage. This adds the *other* field the same one-shot cannot
+carry: the environment-derived client URLs.
+
+**The trigger.** prod is moving from `prod.home.keithjackson.dev` to the apex `home.keithjackson.dev`.
+`BASE_DOMAIN` is live — the realm import carries **26** `${BASE_DOMAIN}` references and 39 files under
+`platform/` + `apps/` reference it — so flipping the knob re-renders every declared redirect URI in
+git. It reaches Keycloak's database **never**: the `KeycloakRealmImport` rests at
+`Done=True / Started=False` and does not re-run. Measured on prod's live CR:
+`https://grafana.prod.home.keithjackson.dev/login/generic_oauth`, i.e. substitution demonstrably
+happened at the *current* value and then froze. After the flip, every OIDC login fails with a
+`redirect_uri` mismatch while the CR still reads `Done=True` and nothing alerts. Identical shape to
+the literal-`(env:...)` placeholder outage: **declared correctly in git, not in effect, behind a
+green signal.**
+
+### Decisions
+
+| # | Decision | Why |
+|---|---|---|
+| K1 | **EXTEND** the existing reconciler with a second pass; do NOT add a sibling CronJob | Decisive reason: a URL write needs **no new endpoint**. It is the same minimal `PUT /admin/realms/<realm>/clients/<uuid>`, and the current URLs already come back in the allow-listed client lookup. So the hard allow-list that makes `/users`, `/groups`, `/roles`, `/authentication` unreachable is widened by *nothing* and is preserved rather than re-declared in a second copy. The ConfigMap also carries exactly one script key by L0 contract, so a sibling would have had to fork ~300 lines of safety-critical code the file header explicitly forbids forking. Blast radii were already identical (client representations only), so separating them bought nothing real. |
+| K2 | The desired state is **GENERATED** from the realm import (`ci/render-keycloak-client-urls.py`), gated by L0 `--check` | The pod has `automountServiceAccountToken: false` and cannot read the `KeycloakRealmImport` CR, so its desired state must be mounted. A hand-authored ConfigMap would be a second declaration of every public hostname, free to disagree with the import — the same shape as the bug. Generated + gated makes them provably identical. Same `render==golden` idiom as `catalog/render.py`. |
+| K3 | URL strings are copied **verbatim**, tokens included; the renderer never parses a hostname and never reads `cluster-vars` | `client-urls.yaml` therefore carries `https://grafana.${BASE_DOMAIN}/...` unchanged, and L0 asserts it is rendered by the **same** Flux Kustomization as the import. `postBuild.substituteFrom` is per-Kustomization, so a split would let one token resolve to two values and the realm would converge on a hostname the HTTPRoutes do not serve. There is exactly one place the domain is decided, and **no new substitution variable** was introduced. |
+| K4 | The two passes **fail closed independently** | If a malformed URL ConfigMap could abort the run, a hostname typo would stop client-*secret* repair — making credential healing depend on a file that has nothing to do with credentials, a strictly worse posture than before pass 2 existed. Each pass reads its own input, fails closed for its own fields, and the exit code is the OR. |
+| K5 | List fields compare **order-insensitively** (`sorted`, not `set`) | Keycloak does not preserve the authored order of `redirectUris`. An order-sensitive compare would rewrite every client on every run forever while reporting success. `sorted` keeps duplicates as drift. |
+| K6 | A field the desired state omits is **UNMANAGED**, never forced to empty | Only `redirectUris`/`webOrigins` are declared today. Reading absence as "must be empty" would wipe an operator-set `adminUrl`, or any field a future Keycloak version populates itself. |
+| K7 | Public clients' **URLs are managed** even though their secrets are not | `kubernetes` is PKCE-public and its localhost callbacks are what `kubectl` logins land on; a stale URI on any client widens what the realm will redirect to. |
+| K8 | **Extend** the existing `KeycloakClientSecretReconcilerFailing`/`…Stale` pair rather than adding a second | One CronJob ⇒ one Failing/Stale pair. A second pair keyed to the same `job_name` regex would fire twice for a single cause and train the operator to ignore both. The CronJob exports no metrics of its own, so there is no *new* series to alert on — inventing a rule would have meant inventing a signal. No new critical, nothing permanently firing. |
+| K9 | Commit a **mutation harness** and run it in L0 (~20s) | A passing selftest proves nothing if it cannot fail, and "reported success while the realm was broken" is the exact failure this component exists to end. `mutations.py` injects 12 plausible regressions into the *extracted* script and requires `--selftest` to catch each. Two **survived on the first run** — order-insensitivity and readback verification were untested — and the suite was strengthened until all 12 were killed. That is the harness earning its place, not decoration. |
+
+### Evidence
+
+- reconciler `--selftest`: **84 assertions** pass (up from 39). Covers the domain flip, a client
+  *gaining* a URI, a client *losing* a stale one, a public client's URLs managed while its secret is
+  not, an unmanaged field surviving untouched, per-pass fail-closed, order-insensitivity, and a
+  server that accepts a `PUT` with 204 and does not apply it.
+- `mutations.py`: **12/12 injected regressions killed.**
+- L0 `keycloak-client-secret-reconciler`: **212 assertions.** Verified to FAIL when
+  `client-urls.yaml` is hand-edited away from the realm import.
+- The renderer's own `--check` verified to FAIL and print a diff on a drifted redirect URI.
+
+**Verified against the LIVE prod realm, read-only** (`CLUSTER=prod ... --context k3s-prod`, admin API
+via port-forward, `--audit` mode which provably never writes):
+
+- prod's `KeycloakRealmImport` reads `Done=True / Started=False / HasErrors=False` — the one-shot
+  state, confirmed.
+- Its `spec` carries the SUBSTITUTED value `https://grafana.prod.home.keithjackson.dev/...`, and all
+  13 clients' stored URLs sit on `prod.home.keithjackson.dev`. Substitution demonstrably happens and
+  then freezes.
+- Running the shipped script's `--audit` at prod's CURRENT `BASE_DOMAIN`: **all 13 clients report
+  `urls ok (already correct, no write)`** and it emits `KEYCLOAK_CLIENT_URLS_AUDIT_OK`. The realm is
+  converged today, so the reconciler would be a no-op right now — which is the correct baseline.
+- Re-running with the desired state rendered at the POST-FLIP apex value: **24 drifted fields across
+  12 clients**, each naming the exact before/after, while `kubernetes` correctly reports `ok` (its
+  localhost callbacks are not domain-derived, so it must not drift). That is the precise damage the
+  apex flip will do to SSO, detected, with zero false positives.
+- The same run had pass 1 fail closed on an empty secrets dir while pass 2 completed normally —
+  K4's independence, demonstrated live rather than only in the selftest.
+
+**K5 (order-insensitivity) turned out to be measured, not defensive.** The live realm stores
+`kubernetes`' 8 redirect URIs and `oauth2-proxy`' 2 in a DIFFERENT ORDER than git declares them —
+Keycloak genuinely reorders them. An order-sensitive comparison would therefore have rewritten those
+two clients on **every run, every 15 minutes, forever**, reporting success each time. Both report
+converged under `sorted()`.
+
+### Process note — I initially reported three false findings, from reading the wrong ref
+
+Worth recording because the mistake is cheap to repeat. My first pass concluded that the reconciler
+was absent from `main`, that the realm import was not templated, and that `BASE_DOMAIN` was a dead
+knob. **All three were wrong.** I had diffed against `origin/main`, and `origin` is *dev's* Gitea,
+stale at `4809199`; the live remote is `prod-gitea`, with `main` at `fa4deac` — 68 commits ahead. On
+the real `main` the reconciler is present (delivered file-level, not via a merge, so it is not an
+ancestor of a branch cut from the old ref), the import carries 26 `${BASE_DOMAIN}` references, and 39
+files reference the knob.
+
+Consequences avoided: the branch was rebased off the stale base before merging. As-is it was 221
+files / 20,328 deletions against `main` and would have reverted velero's R2 enablement, the VPN egress
+gateway and the arr config-PVC fix. Rebasing also picked up a reconciler fix that only exists on real
+`main` — `fsGroup: 65532` with the client-secrets volume at `defaultMode: 0440`, without which the
+container dies with `PermissionError` on every run; my older base had `0400` and no `fsGroup`.
+
+**Rule for future agents in this repo: `origin` is not the source of truth. Diff against
+`prod-gitea/main`, or local `main` after confirming it matches.**
+
+### Still open
+
+- `https://${BASE_DOMAIN}/runbooks/keycloak-client-secrets` is referenced by both alerts and still
+  does not exist.
+- The apex flip itself is `migration/dns-apex-inversion`'s job. This change only guarantees the realm
+  follows git once the knob moves; it does not move it.