   creator = useTracker ->
     displayUser message.creator
   , [message.creator]
-  children = useTracker ->
-    childrenLookup message
-  , [message]
+  children = useChildren message
   inner =
     <>
       {unless root

  formattedBody = useTracker ->
    formatBody historified.format, historified.body
  , [historified.format, historified.body]
  children = useTracker ->
    childrenLookup message
  , [message]
  ref = useRefTooltip()

  onFold = (e) ->

childrenLookup = (message) ->
  ## Lookup children in message.children, and annotate with extra fields
  ## `parent` and `index`.
  ## Alternate approach: single call to Messages.find
  #childrenByID = {}
  #Messages.find _id: $in: message.children
  #.forEach (child) -> childrenByID[child._id] = child
  for childID, index in message.children
    child = Messages.findOne childID #childrenByID[childID]
    continue unless child?
    ## Use canSee to properly fake non-superuser mode.
    continue unless canSee child
