CallerMiddleware silently preferred X-Auth-Request-User over X-Forwarded-User
with no explanation and no signal when both were set. Documented the precedence
(X-Auth-Request-User is the verified OIDC identity oauth2-proxy sets, so it is
authoritative; X-Forwarded-User is a fallback), and it now takes a *slog.Logger
and warns when both headers are present and disagree, so a proxy
misconfiguration is visible instead of silently resolved. Table-driven tests
cover precedence (both/single/none) and the conflict-warning path.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
mathiasandClaude Opus 4.8
9b7f53bdda