v0.91.2 — log a healthy credential probe at Debug

The probe logged only on failure, so a healthy one was silent: "no auth_failed" was
indistinguishable from "never probed", and the leg could not be demonstrated as running.
That is exactly how v0.91.0 shipped it inert unnoticed.

internal/pbs/live_reporter.go

@@ -100,6 +100,10 @@ func (r *LiveSnapshotReporter) probeAuthAndReport(ctx context.Context, t Target)
 	err := r.probeAuth(ctx, t)
 	switch {
 	case err == nil:
+		// Logged even on success: a safety mechanism that is silent when healthy cannot be shown to be
+		// RUNNING, and "no auth_failed" is indistinguishable from "never probed". Debug level, so it
+		// costs nothing in normal operation but is one log-level away when it matters.
+		r.log.Debug("pbs: credential probe OK", "storage", t.StorageID, "datastore", t.Datastore)
 		r.authSink.NoteAuthResult(t.StorageID, false, "")
 	case errors.Is(err, ErrUnauthorized):
 		// The one case that is TERMINAL and actionable: the credential is rejected, not the network.