Establish the live state and find a rollout precondition for G10

G10 waits on custody and platform owners and cannot close from here. What was
doable: verify the handoffs actually went out, replace a remembered live state
with an observed one, and find out whether main is safe to deploy. The last
question found a defect in this repository's own recent work.

Handoffs verified independently rather than trusted: all seven messages are in
the hub with receipt ids. This gap was reopened once for claimed-but-unsent
delivery, so the claim deserved the same scrutiny.

Live state read from the cluster read-only: image main-153258b, only the Qonto
secret materialized so the approval clients remain unprovisioned, four registered
clients, no tenantEngine block. That also corrects an earlier claim of mine --
the deployed config sets userOU explicitly, so the KEY-WP-0023 default fix was
never a production issue.

The precondition: KEY-WP-0019 discovers the expected issuer from
authelia.tokenBaseURL, and the deployed Authelia derives its advertised issuer
from the request Host, advertising the in-cluster address to KeyCape and the
browser-facing one to browsers. Verification fails closed, so a mismatch breaks
every human login and looks like a broken login rather than a misconfiguration.
Which value the token carries needs a real login against production to settle and
was not determined here.

Two mitigations: docs/operations.md documents pinning authelia.issuer and
jwksUrl, with the curl that reveals what the provider advertises for a given
Host; and the authentication failure event now carries a specific reason, so
id_token_issuer_mismatch is distinguishable from a signature failure or an
unreachable key set. The browser still learns nothing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NV9oijZukGyGbRQGGKnK4P

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 713576@bnt-lap001
Assistant-Session: 384c511d-9bce-4cb8-a676-2aef6c0c8df6

src/internal/adapters/authelia/adapter.go

@@ -101,7 +101,10 @@ func (a *AutheliaAdapter) HandleCallback(ctx context.Context, params domain.Call
 			EventType: telemetry.EventAuthFailure,
 			Endpoint:  "/api/oidc/token",
 			Result:    "failure",
-			ErrorType: "id_token_verification_error",
+			// Name which check failed: an issuer mismatch from a provider that
+			// derives its issuer from the request Host is a misconfiguration,
+			// not an attack, and is indistinguishable from one without this.
+			ErrorType: FailureReason(err),
 		})
 		return nil, domain.ErrAuthFailed
 	}