diff --git a/os2.rkt b/os2.rkt
index e93b7ad..718728e 100644
--- a/os2.rkt
+++ b/os2.rkt
@@ -66,17 +66,18 @@
 	    pending-actions ;; QuasiQueue<(cons PID Action)>
 	    ) #:transparent)
 
-(struct endpoint (id ;; EID
-		  topic ;; Topic
-		  handlers ;; Handlers
-		  ) #:transparent)
+;; An Endpoint is an (endpoint EID Topic Handlers), representing a
+;; facet of a process responsible for playing a particular role (the
+;; topic) in a conversation.
+(struct endpoint (id topic handlers) #:transparent)
 
-(struct process (id ;; PID
-		 state
-		 next-endpoint-id-number ;; NonnegativeInteger
-		 endpoints ;; Set<EID>
-		 ) #:transparent)
+;; A Process is an Exists State . (process PID State
+;; NonnegativeInteger Set<EID>), representing a VM process and its
+;; collection of active endpoints.
+(struct process (id state next-eid-number endpoints) #:transparent)
 
+;; A Topic is a (topic Role Pattern Boolean), describing an Endpoint's
+;; role in a conversation.
 (struct topic (role pattern virtual?) #:prefab)
 
 ;; InterruptK = State -> Transition
@@ -242,7 +243,7 @@
 
 (define (do-subscribe pid topic hs k state)
   (define old-process (hash-ref (vm-processes state) pid))
-  (define eid-number (process-next-endpoint-id-number old-process))
+  (define eid-number (process-next-eid-number old-process))
   (define new-eid (list pid eid-number))
   (struct-copy vm (for*/fold ([state (run-trapk state pid k new-eid)])
 		      ([(matching-pid p) (in-hash (vm-processes state))]
@@ -271,7 +272,7 @@
 	       [processes (hash-set (vm-processes state)
 				    pid
 				    (struct-copy process old-process
-						 [next-endpoint-id-number (+ eid-number 1)]
+						 [next-eid-number (+ eid-number 1)]
 						 [endpoints
 						  (set-add (process-endpoints old-process)
 							   new-eid)]))]
@@ -332,8 +333,7 @@
 (define (run-trapk state pid trap-k . args)
   (if trap-k
       (let ((failure-proc (lambda (e) (lambda (process-state)
-					(transition process-state
-					  (kill #f e))))))
+					(transition process-state (kill #f e))))))
 	(run-ready state pid (apply send-to-user failure-proc trap-k args)))
       state))
 
@@ -344,29 +344,26 @@
 
 (define (run-ready state pid interrupt-k)
   (define old-process (hash-ref (vm-processes state) pid))
-  (match-define (transition new-process-state actions)
+  (define old-state (process-state old-process))
+  (match-define (transition new-state actions)
     (maybe-transition->transition
-     (send-to-user (lambda (e) (transition (process-state old-process) (kill #f e)))
-		   interrupt-k
-		   (process-state old-process))))
+     (send-to-user (lambda (e) (transition old-state (kill #f e))) interrupt-k old-state)))
   (struct-copy vm (enqueue-actions state pid actions)
 	       [processes (hash-set (vm-processes state) pid
 				    (struct-copy process old-process
-						 [state new-process-state]))]))
+						 [state new-state]))]))
 
 (define (do-spawn spawning-pid thunk k state)
   (match-define (transition initial-state initial-actions)
     (send-to-user (lambda (e) (transition #f (kill #f e))) thunk))
   (define new-pid (vm-next-process-id state))
-  (run-trapk (struct-copy vm (enqueue-actions state new-pid initial-actions)
-			  [processes (hash-set (vm-processes state) new-pid (process new-pid
-										     initial-state
-										     0
-										     (set)))]
-			  [next-process-id (+ new-pid 1)])
-	     spawning-pid
-	     k
-	     new-pid))
+  (define spawned-state
+    (struct-copy vm (enqueue-actions state new-pid initial-actions)
+		 [processes (hash-set (vm-processes state)
+				      new-pid
+				      (process new-pid initial-state 0 (set)))]
+		 [next-process-id (+ new-pid 1)]))
+  (run-trapk spawned-state spawning-pid k new-pid))
 
 (define (do-kill pid-to-kill reason state)
   (cond
@@ -384,10 +381,8 @@
 	       [pending-actions (append (reverse (for/list ([a (flatten actions)]) (cons pid a)))
 					(vm-pending-actions state))]))
 
-(define (wrap-trapk pid trapk)
-  (lambda args
-    (lambda (state)
-      (apply run-trapk state pid trapk args))))
+(define (((wrap-trapk pid trapk) . args) state)
+  (apply run-trapk state pid trapk args))
 
 (define (transform-meta-action pid preaction)
   (match preaction