The ScadaBridge live gate (check 4) found SecretsHubAuthInterceptor denying
correctly but logging nothing: the only trace of a refusal was a framework
Grpc.AspNetCore.Server Information line. A follower whose bearer token was
mis-rotated therefore stopped converging silently, with the hub showing it
only at INF.
Every denial is now counted and summarised in a Warning emitted on the first
denial after startup or after a 60-second quiet window, carrying the denials
since the previous summary plus a breakdown by cause. A single probe is
visible immediately; a sustained flood is bounded to one line per window,
which is what makes warning safe at all — the endpoint is unauthenticated by
construction, so a per-denial warning would be an unbounded log write driven
by an unauthenticated caller. Counters are Interlocked and the emit is
decided by a compare-exchange on the last-emit timestamp, so exactly one
thread emits per window and a denial counted after the drain carries into
the next summary rather than being lost.
The cause breakdown is server-side diagnostics only. Denied() is untouched:
every rejection still returns the identical uniform Unauthenticated status,
the comparison is still constant-time, and no token material appears in any
log line. The existing warn-once-on-unconfigured-token signal is unchanged
and still emitted exactly once; denials in that state count toward the new
summary's "unconfigured" category.
TimeProvider is an optional default-valued parameter rather than a second
overload — the type must keep exactly one public constructor or the gRPC
interceptor activator silently stops invoking the auth gate.
Two existing tests scoped their assertions to the configuration warning,
since both kinds now share a category: the new line is deliberate behavior,
not drift.
Claude-Session: https://claude.ai/code/session_014WNM4vjoVksyyBraTXSZE1
Joseph Doherty
c86cead5c2