diff --git a/src/syndicate.nim b/src/syndicate.nim
index b26ccba..35e8524 100644
--- a/src/syndicate.nim
+++ b/src/syndicate.nim
@@ -156,11 +156,23 @@ macro onRetracted*(class: static[RecordClass]; doHandler: untyped) =
 macro onMessage*(class: static[RecordClass]; doHandler: untyped) =
   onEvent(messageEvent, class, doHandler)
 
-template assert*(class: RecordClass; field: untyped): untyped =
+template onStart*(body: untyped): untyped =
+  mixin getCurrentFacet
+  getCurrentFacet().addStartScript do (facet: Facet):
+    proc getCurrentFacet(): Facet {.inject, used.} = facet
+    body
+
+template onStop*(body: untyped): untyped =
+  mixin getCurrentFacet
+  getCurrentFacet().addStopScript do (facet: Facet):
+    proc getCurrentFacet(): Facet {.inject, used.} = facet
+    body
+
+template assert*(class: RecordClass; fields: varargs[Preserve, toPreserve]): untyped =
   mixin getCurrentFacet
   let facet = getCurrentFacet()
   discard facet.addEndpoint do (_: Facet) -> EndpointSpec:
-    let a = init(class, getPreserve(field))
+    let a = init(class, fields)
     result.assertion = some(a)
 
 template field*(F: untyped; T: typedesc; initial: T): untyped =