fix(authentik): census and repair the OAuth defaults on every proxy provider

A proxy provider built by hand in `ak shell` never runs
ProxyProvider.set_oauth_defaults() — the REST serializer does, the ORM does not —
so the row looks fully configured while redirect_uris is empty (they are derived
from external_host by _get_callback_url()), grant_types is [], and
authorization_flow is NULL. Each one kills a guarded login in a different,
unrelated-looking way, all before any credential is requested: authentik's own
"Redirect URI Error" page, then a bodiless HTTP 400 from /application/o/authorize/
once the URIs are filled by hand, and a 500 NoneType.slug in the flow planner.
abs-proxy (abs.franksdank.cloud) hit the first two on 2026-11-03.

The script calls the vendor's own set_oauth_defaults() and points the
authorization flow at default-provider-authorization-implicit-consent for every
proxy provider, idempotently; a provider that already matches is untouched, so a
deliberate deviation is never flattened. `--check` is the census (exit 1 on
drift, writes nothing) for gate use. Applied live 2026-11-03: abs-proxy fixed,
the other ten (REST-created) already compliant, census now reports drift: 0.

This is authentik DB state and no deployable file carries it — a blueprint
re-import or an ak-shell re-creation reverts it and the symptom returns, so the
law and the failure signatures are recorded on the outpost page as provisioning
rule 3.

scripts/authentik-proxy-provider-defaults.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+# Census and repair the OAuth2 defaults on every authentik PROXY provider.
+#
+# A proxy provider built by hand in `ak shell` never runs
+# ProxyProvider.set_oauth_defaults() — the REST serializer calls it, the ORM does
+# not — so the row looks perfectly configured (external_host, internal_host,
+# application bound, embedded-outpost claim present) while three OAuth facts are
+# blank. Each one kills the guarded login in a different, unrelated-looking way,
+# all BEFORE any credential is asked for:
+#
+#   * redirect_uris empty -> authentik answers its own page:
+#     "Redirect URI Error — The request fails due to a missing, invalid, or
+#     mismatching redirection URI (redirect_uri)". Measured on abs-proxy
+#     (abs.franksdank.cloud) 2026-11-03.
+#   * grant_types empty -> the authorize endpoint refuses the outpost's
+#     authorization-code request with a bodiless HTTP 400 (Chromium renders
+#     "This page isn't working / HTTP ERROR 400"). Same provider, one step
+#     later, after the URIs were filled in by hand.
+#   * authorization_flow NULL -> the authorize view crashes building its flow
+#     planner: AttributeError 'NoneType' object has no attribute 'slug', HTTP
+#     500. That is what authentik-grafana-sso-fix.sh exists for.
+#
+# So: a guard that shows ANY of those three pages is not an Anubis problem and
+# not a Caddy problem — run this script before touching the route.
+#
+# Repair calls the VENDOR's own set_oauth_defaults() (grant_types = authz code +
+# client credentials + password, confidential client, the stock scope mappings,
+# redirect_uris derived from external_host by _get_callback_url) and points the
+# authorization flow at default-provider-authorization-implicit-consent, the flow
+# every working provider here uses. Providers that already match are untouched,
+# so a deliberate per-provider deviation is never silently flattened.
+#
+# This is authentik DB state. It is NOT in any deployable file: a blueprint
+# re-import, or an ak-shell re-creation of a provider, reverts these facts and
+# the symptom returns verbatim. Re-run after any such rebuild. Idempotent.
+#
+# Usage: authentik-proxy-provider-defaults.sh [--check]
+#          no argument  repair what drifts, print one line per provider
+#          --check       census only, exit 1 if anything drifts (gate use)
+#        override host: AUTHENTIK_HOST=…
+set -euo pipefail
+HOST="${AUTHENTIK_HOST:-dankclaw}"
+MODE="${1:-}"
+case "$MODE" in
+    "" | --check) : ;;
+    *) echo "usage: $(basename "$0") [--check]" >&2; exit 2 ;;
+esac
+
+ssh "$HOST" 'podman exec -i authentik-server ak shell' <<PYEOF
+from authentik.flows.models import Flow
+from authentik.providers.proxy.models import ProxyProvider, _get_callback_url
+
+CHECK = $( [ "$MODE" = "--check" ] && echo True || echo False )
+FLOW = "default-provider-authorization-implicit-consent"
+WANT_GRANTS = ["authorization_code", "client_credentials", "password"]
+
+flow = Flow.objects.filter(slug=FLOW).first()
+if not flow and not CHECK:
+    raise SystemExit("flow %s is missing; nothing was changed" % FLOW)
+
+drift = 0
+for p in ProxyProvider.objects.all().order_by("pk"):
+    want_uris = [u.url for u in _get_callback_url(p.external_host)]
+    have_uris = [u.url for u in p.redirect_uris]
+    bad = []
+    if [str(g) for g in p.grant_types] != WANT_GRANTS:
+        bad.append("grant_types=%s" % [str(g) for g in p.grant_types])
+    if have_uris != want_uris:
+        bad.append("redirect_uris=%s" % have_uris)
+    if p.authorization_flow_id is None:
+        bad.append("authorization_flow=None")
+    if not bad:
+        print("ok   %s (ext %s)" % (p.name, p.external_host))
+        continue
+    drift += 1
+    if CHECK:
+        print("DRIFT %s: %s" % (p.name, "; ".join(bad)))
+        continue
+    print("fix  %s: %s" % (p.name, "; ".join(bad)))
+    p.set_oauth_defaults()
+    if p.authorization_flow_id is None:
+        p.authorization_flow = flow
+    p.save()
+    after = ProxyProvider.objects.get(pk=p.pk)
+    print("     -> grants %s, %d redirect URIs, flow %s"
+          % ([str(g) for g in after.grant_types], len(after.redirect_uris),
+             after.authorization_flow and after.authorization_flow.slug))
+
+print("providers checked, drift: %d" % drift)
+raise SystemExit(1 if (CHECK and drift) else 0)
+PYEOF
+
+echo "Verify: walk the guarded vhost in a browser — Anubis solves, authentik"
+echo "renders its login form (no Redirect URI Error, no HTTP 400), and the"
+echo "callback lands back on the app."