diff --git a/syndicate-examples/speed-tests/box-and-client/without-dataspace.rkt b/syndicate-examples/speed-tests/box-and-client/without-dataspace.rkt
index 30e340c..0d01b7a 100644
--- a/syndicate-examples/speed-tests/box-and-client/without-dataspace.rkt
+++ b/syndicate-examples/speed-tests/box-and-client/without-dataspace.rkt
@@ -19,7 +19,7 @@
                         'setter
                         (embedded
                          (object #:name 'update-handler
-                                 [#:asserted new-value
+                                 [#:message new-value
                                   (reporter new-value)
                                   (when (= new-value LIMIT) (stop-facet root-facet))
                                   (value new-value)]))))))
@@ -49,7 +49,7 @@
     (define root-facet this-facet)
     (define disarm (facet-prevent-inert-check! this-facet))
     (box (object #:name 'box-boot-handler
-                 [#:asserted refs
+                 [#:message refs
                   (log-info "refs ~v" refs)
                   (match-define (hash-table ('getter (embedded g))
                                             ('setter (embedded s))) refs)
diff --git a/syndicate/drivers/tcp.rkt b/syndicate/drivers/tcp.rkt
index 40f9c55..c24a1d0 100644
--- a/syndicate/drivers/tcp.rkt
+++ b/syndicate/drivers/tcp.rkt
@@ -75,9 +75,9 @@
        (at local-peer
          (assert (ActiveSocket-controller
                   (object #:name (list name 'socket)
-                          [#:asserted (Socket-credit amount mode) (issue-credit amount mode)]
-                          [#:asserted (Socket-data data mode) (relay data mode)]
-                          [#:asserted (Socket-eof) (close-output-port o)]))))))))
+                          [#:message (Socket-credit amount mode) (issue-credit amount mode)]
+                          [#:message (Socket-data data mode) (relay data mode)]
+                          [#:message (Socket-eof) (close-output-port o)]))))))))
 
 (define (spawn-inbound ds custodian i o spec)
   (define name (call-with-values (lambda () (tcp-addresses i #t)) list))
@@ -104,14 +104,14 @@
         [#:asserted (ActiveSocket-close message)
          (log-syndicate/drivers/tcp-debug "closing ~v:\n~a" this-actor message)
          (stop-current-facet)]
-        [#:asserted (ActiveSocket-Socket (Socket-credit amount mode))
+        [#:message (ActiveSocket-Socket (Socket-credit amount mode))
          (if issue-credit
              (issue-credit amount mode)
              (log-syndicate/drivers/tcp-warning
               "Socket-credit ~v/~v ignored because no controller present" amount mode))]
-        [#:asserted (ActiveSocket-Socket (Socket-data data mode))
+        [#:message (ActiveSocket-Socket (Socket-data data mode))
          (relay data mode)]
-        [#:asserted (ActiveSocket-Socket (Socket-eof))
+        [#:message (ActiveSocket-Socket (Socket-eof))
          (close-output-port o)]))
     (at ds
       (assert (ConnectionPeer handle (TcpRemote (caddr name) (cadddr name))))
@@ -246,9 +246,9 @@
              #:retracted
              (on-disconnected)]
             [#:asserted (ActiveSocket-close message) (on-rejected message)]
-            [#:asserted (ActiveSocket-Socket (Socket-credit amount mode)) (on-credit amount mode)]
-            [#:asserted (ActiveSocket-Socket (Socket-data data mode)) (on-data data mode)]
-            [#:asserted (ActiveSocket-Socket (Socket-eof)) (on-eof)]))
+            [#:message (ActiveSocket-Socket (Socket-credit amount mode)) (on-credit amount mode)]
+            [#:message (ActiveSocket-Socket (Socket-data data mode)) (on-data data mode)]
+            [#:message (ActiveSocket-Socket (Socket-eof)) (on-eof)]))
   (at ds (assert (Connection s spec))))
 
 (define (send-credit conn amount mode)
diff --git a/syndicate/syntax.rkt b/syndicate/syntax.rkt
index c45e8b8..8a40439 100644
--- a/syndicate/syntax.rkt
+++ b/syndicate/syntax.rkt
@@ -92,15 +92,15 @@
     [(_ name-stx:<name> handler ...)
      #`(let ((state (make-hash)))
          (define name name-stx.N)
-         (define (handler-function assertion)
-           (-object-clauses name assertion [] [handler ...]))
+         (define (handler-function assertion is-message?)
+           (-object-clauses name assertion is-message?  [] [handler ...]))
          (ref (entity #:name name
                       #:assert (lambda (m h) (-object-assert state handler-function m h))
                       #:retract (lambda (h) (-object-retract state h))
                       #:message (lambda (m) (-object-message handler-function m)))))]))
 
 (define (-object-assert state handler-function assertion handle)
-  (define k (handler-function assertion))
+  (define k (handler-function assertion #f))
   (when k (hash-set! state handle k)))
 
 (define (-object-retract state handle)
@@ -110,44 +110,56 @@
     (k)))
 
 (define (-object-message handler-function message)
-  (define k (handler-function message))
+  (define k (handler-function message #t))
   (when k
     (k)))
 
 (define-syntax (-object-clauses stx)
   (syntax-parse stx
-    [(_ name input [completed ...] [])
+    [(_ name input is-message? [completed ...]
+        [])
      #'(match input
          completed ...
          [_
-          (log-syndicate/object-debug "Unhandled assertion ~v in ~v" input name)
+          (log-syndicate/object-debug "Unhandled ~a ~v in ~v"
+                                      (if is-message? "message" "assertion")
+                                      input name)
           #f])]
 
-    [(_ name input [completed ...] [ [#:spawn pat body ...] more ... ])
+    [(_ name input is-message? [completed ...]
+        [ [#:message pat body+ ...] more ... ])
      #'(-object-clauses name
                         input
-                        [completed ...]
-                        [ [#:during pat (spawn/link body ...)] more ... ])]
+                        is-message?
+                        [ completed ... [(-object-pattern pat) #:when is-message?
+                                         body+ ... #f] ]
+                        [more ...])]
 
-    [(_ name input [completed ...] [ [#:asserted pat body+ ... #:retracted body- ...] more ... ])
+    [(_ name input is-message? [completed ...]
+        [ [#:asserted pat body+ ... #:retracted body- ...] more ... ])
      #`(-object-clauses name
                         input
-                        [ completed ... [(-object-pattern pat)
+                        is-message?
+                        [ completed ... [(-object-pattern pat) #:when (not is-message?)
                                          body+ ...
                                          #,(if (null? (syntax->list #'(body- ...)))
                                                #`#f
                                                #`(lambda () body- ...))] ]
                         [more ...])]
 
-    [(_ name input [completed ...] [ [#:asserted pat body+ ...] more ... ])
+    [(_ name input is-message? [completed ...]
+        [ [#:asserted pat body+ ...] more ... ])
      #'(-object-clauses name
                         input
+                        is-message?
                         [completed ...]
                         [ [#:asserted pat body+ ... #:retracted] more ... ])]
 
-    [(_ name input [completed ...] [ [pat body ...] more ... ])
+    [(_ name input is-message? [completed ...]
+        [ [pat body ...] more ... ])
      #'(-object-clauses name
                         input
+                        is-message?
                         [completed ...]
                         [ [#:asserted pat
                            (define f (react (facet-prevent-inert-check! this-facet) body ...))