Replace one instance of yield with a use of wait-for.

new-server.rkt

@@ -133,6 +133,14 @@
      (flush-output)
      state]))
 
+(define-syntax-rule (wait-for topic-of-interest #:state state action ...)
+  (let ((role-name (gensym 'wait-for)))
+    (role role-name topic-of-interest
+      #:state state
+      #:on-presence (sequence-actions state
+		      (delete-role role-name)
+		      action ...))))
+
 (define (session-vm local-addr remote-addr)
   (define local-identification #"SSH-2.0-RacketSSH_0.0")
 
@@ -160,12 +168,13 @@
 	    (spawn (ssh-writer local-addr remote-addr)
 		   #:exit-signal? #t
 		   #:debug-name 'ssh-writer)
-	    ;; (Wait for a cycle to let the reader and writer get
-	    ;; started, then tell the reader we are ready for a single
-	    ;; packet and spawn the session manager.)
-	    ;; TODO: try using presence instead of the yield.
-	    (yield #:state state
-	      (transition state
+	    ;; Wait for the reader and writer get started, then tell
+	    ;; the reader we are ready for a single packet and spawn
+	    ;; the session manager.
+	    (wait-for (topic-subscriber (inbound-packet (wild) (wild) (wild) (wild)) #:monitor? #t)
+	      #:state state
+	      (wait-for (topic-publisher (outbound-packet (wild)) #:monitor? #t)
+		#:state state
 		(send-message (inbound-credit 1))
 		(spawn (ssh-session local-identification
 				    remote-identification