docs(obs): record that the gate-sidecar scrape works — four places still said it did not

PR #49 (merged 21c88b0) fixed the blocked scrape and it is verified working on prod
2026-10-05: all 6 targets up == 1, health=up, lastError='', lastScrapeDuration 0.001-0.006s
against 10.0s and "context deadline exceeded" before. oauth2_proxy_* is in the TSDB for
these namespaces for the first time (5 metric names, 148 series).

Four places in the tree still asserted the pre-fix state as current, in the present tense,
in the files a reader consults first:

  platform/oauth2-proxy/podmonitor.yaml  "READ THIS BEFORE BELIEVING THE TARGETS ARE UP:
    THE SCRAPE IS CURRENTLY DENIED BY NETWORKPOLICY" and "SO THE TARGETS BELOW WILL READ
    up == 0 UNTIL AN INGRESS ALLOWANCE LANDS". The first actively instructs the reader to
    disbelieve a correct up == 1. Now a STATUS block with the post-fix numbers, with the
    diagnosis kept below it under an explicit HISTORY heading because it is why the fix is
    shaped the way it is.
  catalog/render.py:159  "THIS IS THE PREREQUISITE ONLY, AND IT IS NOT YET SCRAPED".
  catalog/render.py:1365  the same claim on the sidecar arg.
  platform/oauth2-proxy/README.md  its subsections are dated and so are honest records, but
    a reader hits the stale body long before any correction. A SUPERSEDED pointer now sits
    under the heading and an Update 2026-10-05 section carries the before/after.

The "not scraped" claims are corrected; the "a flag alone is not enough" warning is KEPT
deliberately, because that part is still true and "flag without ingress allowance" is
exactly what caused the 63.7h outage.

Two substantive errors fixed while there, not just tense. The README's "three things are
needed" listed a Service port and a ServiceMonitor — wrong, a PodMonitor targets pod ports
directly, which is why no Service exposes 44180 and the renderer needed no Service change;
following it would have sent someone to edit Service rendering for nothing. And
podmonitor.yaml deferred the fix to "the catalog/renderer, in flight on another branch" —
no such branch existed; it now names r_monitoring_ingress_policy, with a new CRAFTY section
explaining the one namespace this file cannot help.

Comments only in render.py, so the rendered output is byte-identical: no apps/ file and no
golden changes, and therefore no sensitive path and no human approval needed — the opposite
of the PR this documents.

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

platform/oauth2-proxy/README.md

@@ -91,6 +91,10 @@ This proves the R-IDP-02 property (unauthenticated cannot reach the upstream) on
 
 ## Observability: what this component can and cannot see (measured 2026-09-30)
 
+> **SUPERSEDED — read "Update 2026-10-05" at the end of this section first.** The gate sidecars
+> **are** scraped now and the TSDB **does** hold `oauth2_proxy_*` for them. The two subsections
+> below are kept as the dated record of how this was diagnosed, not as current state.
+
 `servicemonitor.yaml` scrapes **this namespace's** deployment and nothing else. On prod that is
 two targets, `job="oauth2-proxy"`, both `up=1`. The complete set of oauth2-proxy-specific series
 in the TSDB is:
@@ -157,3 +161,55 @@ present `up` series. A discovered-but-failing target publishes `up` with value 0
 would have cleared `OAuth2ProxyGateUnobserved` the moment the PodMonitor landed — reporting the gates
 as observed while nothing was being scraped. The unit test pins that scenario; deleting the `== 1`
 fails it and nothing else.
+
+### Update 2026-10-05: the scrape works
+
+PR #49 (merged `21c88b0`) added the missing third piece. `catalog/render.py`'s
+`r_monitoring_ingress_policy` now also fires for the gate sidecar's metrics port, keyed on
+`_needs_oauth2_sidecar`, rendering `<app>-allow-monitoring-scrape` per app: ns `monitoring` → that
+app's `endpointSelector` → TCP 44180 only. Five objects, one each for jackett, pihole, qbittorrent,
+radarr, sonarr.
+
+Measured on prod 2026-10-05 after Flux applied it (`apps-wave-0` 21:37:01Z, `apps-wave-1`
+21:37:46Z):
+
+| | before | after |
+|---|---|---|
+| target health (6) | `down` | `up` |
+| `lastError` | `context deadline exceeded` | `''` |
+| `lastScrapeDuration` | **10.0s** — exactly the `scrapeTimeout` | **0.001–0.006s** |
+| `up` | `0` × 6 | `1` × 6 |
+
+    count by (__name__) ({__name__=~"oauth2_proxy_.*",
+                          namespace=~"jackett|radarr|sonarr|qbittorrent|pihole"})
+      oauth2_proxy_requests_in_flight              => 6
+      oauth2_proxy_requests_total                  => 16
+      oauth2_proxy_response_duration_seconds_bucket => 108
+      oauth2_proxy_response_duration_seconds_sum   => 9
+      oauth2_proxy_response_duration_seconds_count => 9
+
+    sum by (namespace) (oauth2_proxy_requests_total)
+      qbittorrent => 35072    radarr => 23560    sonarr => 1284
+
+`oauth2_proxy_requests_total` is absent for jackett and pihole simply because that counter is not
+created until the gate has served its first request.
+
+**So the auth-churn rule is now writable rather than decorative** — sustained `code="302"` as a
+share of `oauth2_proxy_requests_total`, held across a window longer than the session lifetime. That
+is the rule the 2026-09-30 incident above could not be caught by. It is still unwritten.
+
+**Alert outcome:** all 5 `TargetDown` resolved, and 5 of 6 `OAuth2ProxyGateUnobserved` with them.
+At `repeat_interval: 12h` with `group_by: [alertname, namespace]`, those 11 groups had been
+re-notifying at roughly **22 emails/day** since 2026-10-02; that drops to 2/day.
+
+**`crafty` still fires, and that is correct.** It is a hand-maintained Deployment under
+`platform/crafty`, outside the renderer, whose `oauth2-proxy` container has **no
+`--metrics-address` at all** — no listener, so no port to open and nothing for the PodMonitor's
+pod-label selector to match. Closing it needs the flag and a `metrics` containerPort on crafty's
+own manifest first, then a hand-written allowance beside it. Open follow-up work.
+
+**The paragraph above headed "To close the gap for an app" is superseded**: a *Service* port and a
+ServiceMonitor are **not** required. A PodMonitor targets pod ports directly, which is why no
+Service exposes 44180 and why the renderer needed no Service change. The three things actually
+needed are `--metrics-address` + named container port, a PodMonitor, and the monitoring-ingress
+allowance.