Local SRs.

src/helpers.coffee

@@ -112,7 +112,10 @@ $watch = (collection, {
   # avoid an infinite loop.
   loops = 0
 
+  updating = false
+
   process = (event, items) ->
+    return if updating
 
     # Values are grouped by namespace.
     valuesByNamespace = Object.create null
@@ -162,10 +165,12 @@ $watch = (collection, {
       # changed.
       unless changed is false
         values[namespace] = ctx.value
+        updating = true
         if namespace is 'common'
           collection.touch consumers
         else
           collection.touch (namespace.substr 1)
+        updating = false
 
     loops = previousLoops
 

src/spec.coffee

@@ -502,6 +502,14 @@ module.exports = ->
     }
 
   @rule SR: ->
+    @data = {
+      # Note: not dynamic.
+      host: $link(
+        -> @genval.PBDs[0] ? 'OpaqueRef:NULL'
+        -> @val.host
+      )
+    }
+
     @val = {
       name_label: -> @genval.name_label
 
@@ -521,7 +529,7 @@ module.exports = ->
         if @genval.shared
           @genval.$poolRef
         else
-          null # TODO
+          @data.host
 
       $PBDs: -> @genval.PBDs