boundary.pony.patch

diff --git a/lib/wallaroo/core/boundary/boundary.pony b/lib/wallaroo/core/boundary/boundary.pony
index 6c947cbd3..e6a819535 100644
--- a/lib/wallaroo/core/boundary/boundary.pony
+++ b/lib/wallaroo/core/boundary/boundary.pony
@@ -34,9 +34,11 @@ use "wallaroo/core/routing"
 use "wallaroo/core/tcp_actor"
 use "wallaroo/core/topology"
 use "wallaroo_labs/bytes"
+use "wallaroo_labs/logging"
 use "wallaroo_labs/mort"
 use "wallaroo_labs/time"
 
+use @l[I32](severity: LogSeverity, category: LogCategory, fmt: Pointer[U8] tag, ...)
 
 class val OutgoingBoundaryBuilder
   let _auth: AmbientAuth
@@ -351,7 +353,11 @@ actor OutgoingBoundary is (Consumer & TCPActor)
     _maybe_mute_or_unmute_upstreams()
 
   fun ref receive_ack(acked_seq_id: SeqId) =>
+    @l(Log.debug(), Log.no_cat(), "acked_seq_id %lu > _lowest_queue_id %lu\n".cstring(), acked_seq_id, _lowest_queue_id)
     ifdef debug then
+      if not (acked_seq_id > _lowest_queue_id) then
+        @printf[I32]("not (acked_seq_id %lu > _lowest_queue_id %lu)\n".cstring(), acked_seq_id, _lowest_queue_id)
+      end
       Invariant(acked_seq_id > _lowest_queue_id)
     end