diff --git a/desk/app/activity.hoon b/desk/app/activity.hoon
index 9ee7f17cb0..43cb39bdb0 100644
--- a/desk/app/activity.hoon
+++ b/desk/app/activity.hoon
@@ -48,7 +48,7 @@
   +$  card  card:agent:gall
   ::
   +$  current-state
-    $:  %5
+    $:  %6
         allowed=notifications-allowed:a
         =indices:a
         =activity:a
@@ -135,11 +135,31 @@
   =?  old  ?=(%2 -.old)  (state-2-to-3 old)
   =?  old  ?=(%3 -.old)  (state-3-to-4 old)
   =?  old  ?=(%4 -.old)  (state-4-to-5 old)
-  ?>  ?=(%5 -.old)
+  =?  old  ?=(%5 -.old)  (state-5-to-6 old)
+  ?>  ?=(%6 -.old)
   =.  state  old
-  sync-reads
-  +$  versioned-state  $%(state-5 state-4 state-3 state-2 state-1)
-  +$  state-5  current-state
+  (emit %pass /fix-init-unreads %agent [our.bowl dap.bowl] %poke noun+!>(%fix-init-unreads))
+  +$  versioned-state
+    $%  state-6
+        state-5
+        state-4
+        state-3
+        state-2
+        state-1
+    ==
+  +$  state-6  current-state
+  +$  state-5  _%*(. *state-6 - %5)
+  ++  state-5-to-6
+    |=  old=state-5
+    ^-  state-6
+    =/  [=indices:a =activity:a]
+      (sync-reads indices.old activity.old volume-settings.old)
+    :*  %6
+        allowed.old
+        indices
+        activity
+        volume-settings.old
+    ==
   +$  state-4
     $:  %4
         allowed=notifications-allowed:a
@@ -180,7 +200,7 @@
     :*  %4
         allowed.old
         new-indices
-        (activity-3-to-4 new-indices)
+        (activity-3-to-4 new-indices volume-settings.old)
         volume-settings.old
     ==
   ++  indices-3-to-4
@@ -188,14 +208,14 @@
     ^-  indices:a
     (~(run by indices) |=([=stream:a =reads:a] [stream reads *@da]))
   ++  activity-3-to-4
-    |=  =indices:a
+    |=  [=indices:a vs=volume-settings:a]
     ^-  activity:a
     =/  sources  (sort-sources:src ~(tap in ~(key by indices)))
     %+  roll  sources
     |=  [=source:a =activity:a]
     =/  index  (~(got by indices) source)
     %+  ~(put by activity)  source
-    (summarize-unreads source index)
+    (~(summarize-unreads urd indices activity vs log) source index)
   +$  state-2
     $:  %2
         allowed=notifications-allowed:a
@@ -231,16 +251,19 @@
   ?+  mark  ~|(bad-poke+mark !!)
       %noun
     ?+  q.vase  ~|(bad-poke+mark !!)
+      %refresh-activity  refresh-all-summaries
+      %clean-keys  correct-dm-keys
+      %fix-init-unreads  fix-init-unreads
+    ::
+        %sync-reads
+      =^  indices  activity
+        (sync-reads indices activity volume-settings)
+      cor(indices indices)
+    ::
         %migrate
       =.  state  *current-state
       =.  allowed  %all
       migrate
-        %refresh-activity
-      refresh-all-summaries
-        %clean-keys
-      correct-dm-keys
-        %sync-reads
-      sync-reads
     ==
   ::
       %activity-action
@@ -797,102 +820,63 @@
   =.  allowed  na
   (give-update [%allow-notifications na] [%hose ~])
 ++  summarize-unreads
-  |=  [=source:a =index:a]
-  ^-  activity-summary:a
-  %-  (log |.("summarizing unreads for: {<source>}"))
-  =/  top=time  -:(fall (ram:on-event:a stream.index) [*@da ~])
-  =/  unread-stream=stream:a
-    ::  all base's events are from children so we can ignore
-    ?:  ?=(%base -.source)  ~
-    ::  we don't need to take child events into account when summarizing
-    ::  the activity, so we filter them out
-    ::  TODO: measure performance vs gas+murn+tap+lot
-    =-  ->
-    %^    (dip:on-event:a @)
-        (lot:on-event:a stream.index `floor.reads.index ~)
-      ~
-    |=  [st=@ =time-id:a =event:a]
-    :_  [%.n st]
-    ?.  !child.event  ~
-    `event
-  =/  children  (get-children:src indices source)
-  %-  (log |.("children: {<?:(?=(%base -.source) 'all' children)>}"))
-  (stream-to-unreads source index(stream unread-stream) children top)
-++  stream-to-unreads
-  |=  [=source:a =index:a children=(list source:a) top=time]
-  ^-  activity-summary:a
-  =/  cs=activity-summary:a
-    %+  roll
-      children
-    |=  [=source:a sum=activity-summary:a]
-    =/  =index:a  (~(gut by indices) source *index:a)
-    =/  as=activity-summary:a
-      ?~  summary=(~(get by activity) source)
-        =>  (summarize-unreads source index)
-        .(children ~)
-      u.summary(children ~)
-    %=  sum
-      count  (add count.sum count.as)
-      notify  |(notify.sum notify.as)
-      newest  (max newest.as newest.sum)
-      notify-count  (add notify-count.sum notify-count.as)
-    ==
-  %-  (log |.("children summary: {<cs>}"))
-  =/  newest=time  :(max newest.cs floor.reads.index bump.index top)
-  =/  total
-    ::  if we're a channel, we only want thread notify counts, not totals
-    ::
-    ?:  ?=(%channel -.source)
-      notify-count.cs
-    count.cs
-  =/  notify-count  notify-count.cs
-  =/  main  0
-  =/  notified=?  notify.cs
-  =/  main-notified=?  |
-  =*  stream  stream.index
-  =|  last=(unit message-key:a)
-  ::  for each event
-  ::  update count and newest
-  ::  if reply, update thread state
-  |-
-  ?~  stream
-    :*  newest
-        total
-        notify-count
-        notified
-        ?~(last ~ `[u.last main main-notified])
-        ?:(?=(%base -.source) ~ (sy children))
-        ~
-    ==
-  =/  [[=time =event:a] rest=stream:a]  (pop:on-event:a stream)
-  =/  volume  (get-volume:evt volume-settings -.event)
-  ::TODO  support other event types
-  =*  is-msg  ?=(?(%dm-post %dm-reply %post %reply) -<.event)
-  =*  is-init  ?=(?(%dm-invite %chan-init) -<.event)
-  =*  is-flag  ?=(?(%flag-post %flag-reply) -<.event)
-  =*  supported  |(is-msg is-init is-flag)
-  ?.  supported  $(stream rest)
-  =?  notified  &(notify.volume notified.event)  &
-  =?  notify-count  &(notify.volume notified.event)  +(notify-count)
-  =.  newest  (max newest time)
-  ?.  &(unreads.volume ?=(?(%dm-post %dm-reply %post %reply) -<.event))
-    $(stream rest)
-  =.  total  +(total)
-  =.  main   +(main)
-  =?  main-notified  &(notify:volume notified.event)  &
-  =.  last
-    ?~  last  `key.event
-    last
-  $(stream rest)
+  ~(summarize-unreads urd indices activity volume-settings log)
 ::
+::  when we migrated from chat and channels, we always added an init event
+::  so that we can mark what's been joined and have something affect the
+::  recency so that it ends up in the correct place on the sidebar.
+::  however, we forgot to mark these as read, so we need to do that now.
+::  otherwise we end up with a bunch of dms/channels that are
+::  incorrectly unread.
+++  fix-init-unreads
+  =+  .^(=channels:c %gx (scry-path %channels /v2/channels/full/noun))
+  =.  indices  (fix-channel-init-unreads indices channels)
+  =+  .^  [dms=(map ship dm:ch) clubs=(map id:club:ch club:ch)]
+      %gx  (scry-path %chat /full/noun)
+    ==
+  =.  indices  (fix-dm-init-unreads indices dms clubs)
+  refresh-all-summaries
+++  fix-channel-init-unreads
+  |=  [=indices:a =channels:c]
+  %-  ~(urn by indices)
+  |=  [=source:a =index:a]
+  ::  if we're a channel with only the %chan-init event, we need to set
+  ::  the floor to the last-read time
+  ?.  ?&  ?=(%channel -.source)
+          ?=([[* [[%chan-init *] *]] ~ ~] stream.index)
+      ==
+    index
+  ?~  channel=(~(get by channels) nest.source)  index
+  index(floor.reads last-read.remark.u.channel)
+++  fix-dm-init-unreads
+  |=  [=indices:a dms=(map ship dm:ch) clubs=(map id:club:ch club:ch)]
+  ^-  indices:a
+  %-  ~(urn by indices)
+  |=  [=source:a =index:a]
+  ::  if we're a DM with only the %dm-invite event, we need to set
+  ::  the floor to the last-read time
+  ?.  ?&  ?=(%dm -.source)
+          ?=([[* [[%dm-invite *] *]] ~ ~] stream.index)
+      ==
+    index
+  ?-  -.whom.source
+      %ship
+    ?~  dm=(~(get by dms) p.whom.source)  index
+    index(floor.reads last-read.remark.u.dm)
+  ::
+      %club
+    ?~  club=(~(get by clubs) p.whom.source)  index
+    index(floor.reads last-read.remark.u.club)
+  ==
 ::  previously we used items as a way to track individual reads because
 ::  floors were not local, but we have reverted to local floors and not
 ::  tracking individual reads
 ::
 ++  sync-reads
+  |=  [=indices:a =activity:a vs=volume-settings:a]
   =/  sources  (sort-sources:src ~(tap in ~(key by indices)))
   |-
-  ?~  sources  cor
+  ?~  sources  [indices activity]
   =/  =source:a  i.sources
   =/  =index:a  (~(got by indices) source)
   =/  old-floor  floor.reads.index
@@ -908,13 +892,18 @@
     [~ %.n ?:((gth time-id st) time-id st)]
   =.  reads.index  [new-floor ~]
   ::  with new reads, update our index and summary
-  =.  cor  (refresh-index source index)
-  =/  new=(unit activity-summary:a)  (~(get by activity) source)
-  ?:  !=(?~(old ~ u.old(reads ~)) ?~(new ~ u.new(reads ~)))
+  =.  indices  (~(put by indices) source index)
+  =/  new-summary
+    %+  ~(summarize-unreads urd indices activity vs log)
+      source
+    index
+  =.  activity
+    (~(put by activity) source new-summary)
+  ?:  !=(?~(old ~ u.old(reads ~)) new-summary(reads ~))
     ~&  "%sync-reads: WARNING old and new summaries differ {<source>}"
     ~&  "old floor: {<old-floor>} new floor: {<new-floor>}"
     ~&  "old:  {<old>}"
-    ~&  "new:  {<new>}"
+    ~&  "new:  {<`new-summary>}"
     $(sources t.sources)
   $(sources t.sources)
 ::
@@ -1062,7 +1051,8 @@
   =/  entries  ~(tap by unreads)
   =;  events=(list [time incoming-event:a])
     |-
-    ?~  events  cor
+    ?~  events
+      cor(indices (fix-channel-init-unreads indices channels))
     =.  cor  (%*(. add-event start-time -.i.events) +.i.events)
     $(events t.events)
   |-  ^-  (list [time incoming-event:a])
@@ -1123,7 +1113,8 @@
   =/  entries  ~(tap by unreads)
   =;  events=(list [time incoming-event:a])
     |-
-    ?~  events  cor
+    ?~  events
+      cor(indices (fix-dm-init-unreads indices dms clubs))
     =.  cor  (%*(. add-event start-time -.i.events) +.i.events)
     $(events t.events)
   |-  ^-  (list [time incoming-event:a])
diff --git a/desk/lib/activity.hoon b/desk/lib/activity.hoon
index 114ff50e46..8788bbe43c 100644
--- a/desk/lib/activity.hoon
+++ b/desk/lib/activity.hoon
@@ -172,6 +172,101 @@
   ::
   --
 ::
+++  urd
+  |_  [=indices:a =activity:a =volume-settings:a log=$-((trap tape) _same)]
+  ++  summarize-unreads
+    |=  [=source:a =index:a]
+    ^-  activity-summary:a
+    %-  (log |.("summarizing unreads for: {<source>}"))
+    =/  top=time  -:(fall (ram:on-event:a stream.index) [*@da ~])
+    =/  unread-stream=stream:a
+      ::  all base's events are from children so we can ignore
+      ?:  ?=(%base -.source)  ~
+      ::  we don't need to take child events into account when summarizing
+      ::  the activity, so we filter them out
+      ::  TODO: measure performance vs gas+murn+tap+lot
+      =-  ->
+      %^    (dip:on-event:a @)
+          (lot:on-event:a stream.index `floor.reads.index ~)
+        ~
+      |=  [st=@ =time-id:a =event:a]
+      :_  [%.n st]
+      ?:  child.event  ~
+      `event
+    =/  children  (get-children:src indices source)
+    %-  (log |.("children: {<?:(?=(%base -.source) 'all' children)>}"))
+    (stream-to-unreads source index(stream unread-stream) children top)
+  ++  sum-children
+    |=  children=(list source:a)
+    ^-  activity-summary:a
+    %+  roll
+      children
+    |=  [=source:a sum=activity-summary:a]
+    =/  =index:a  (~(gut by indices) source *index:a)
+    =/  as=activity-summary:a
+      ?~  summary=(~(get by activity) source)
+        =>  (summarize-unreads source index)
+        .(children ~)
+      u.summary(children ~)
+    %=  sum
+      count  (add count.sum count.as)
+      notify  |(notify.sum notify.as)
+      newest  (max newest.as newest.sum)
+      notify-count  (add notify-count.sum notify-count.as)
+    ==
+  ++  stream-to-unreads
+    |=  [=source:a =index:a children=(list source:a) top=time]
+    ^-  activity-summary:a
+    =/  cs=activity-summary:a
+      (sum-children children)
+    %-  (log |.("children summary: {<cs>}"))
+    =/  newest=time  :(max newest.cs floor.reads.index bump.index top)
+    =/  total
+      ::  if we're a channel, we only want thread notify counts, not totals
+      ::
+      ?:  ?=(%channel -.source)
+        notify-count.cs
+      count.cs
+    =/  notify-count  notify-count.cs
+    =/  main  0
+    =/  notified=?  notify.cs
+    =/  main-notified=?  |
+    =*  stream  stream.index
+    =|  last=(unit message-key:a)
+    ::  for each event
+    ::  update count and newest
+    ::  if reply, update thread state
+    |-
+    ?~  stream
+      :*  newest
+          total
+          notify-count
+          notified
+          ?~(last ~ `[u.last main main-notified])
+          ?:(?=(%base -.source) ~ (sy children))
+          ~
+      ==
+    =/  [[=time =event:a] rest=stream:a]  (pop:on-event:a stream)
+    =/  volume  (get-volume:evt volume-settings -.event)
+    ::TODO  support other event types
+    =*  is-msg  ?=(?(%dm-post %dm-reply %post %reply) -<.event)
+    =*  is-init  ?=(?(%dm-invite %chan-init) -<.event)
+    =*  is-flag  ?=(?(%flag-post %flag-reply) -<.event)
+    =*  supported  |(is-msg is-init is-flag)
+    ?.  supported  $(stream rest)
+    =?  notified  &(notify.volume notified.event)  &
+    =?  notify-count  &(notify.volume notified.event)  +(notify-count)
+    =.  newest  (max newest time)
+    ?.  &(unreads.volume ?=(?(%dm-post %dm-reply %post %reply) -<.event))
+      $(stream rest)
+    =.  total  +(total)
+    =.  main   +(main)
+    =?  main-notified  &(notify:volume notified.event)  &
+    =.  last
+      ?~  last  `key.event
+      last
+    $(stream rest)
+  --
 ++  convert-to
   |%
   ++  v4
diff --git a/desk/lib/test-agent.hoon b/desk/lib/test-agent.hoon
index 5b499ed1e8..a2d58ab1db 100644
--- a/desk/lib/test-agent.hoon
+++ b/desk/lib/test-agent.hoon
@@ -352,7 +352,7 @@
     ::
     %+  skip  caz
     |=  =card
-    ?=([%give %fact [[%verb %events ~] ~] *] card)
+    ?=([%give %fact [[%verb ?(%events %events-plus) ~] ~] *] card)
   =/  m  (mare ,~)
   ^-  form:m
   |=  s=state
diff --git a/desk/tests/app/activity.hoon b/desk/tests/app/activity.hoon
index bf1e180b5b..ce3147830d 100644
--- a/desk/tests/app/activity.hoon
+++ b/desk/tests/app/activity.hoon
@@ -1,22 +1,22 @@
-/-  a=activity, g=groups, c=channels
+/-  a=activity, g=groups, c=channels, ch=chat
 /+  *activity, *test-agent
 /=  activity-agent  /app/activity
 |%
 ++  dap  %activity
 ++  test-sync-reads-0
-  =+  state-0
+  =+  state-0:sync-reads
   (run-sync-reads pre-sync post-sync activity 5)
 ::
 ++  test-sync-reads-1
-  =+  state-1
+  =+  state-1:sync-reads
   (run-sync-reads pre-sync post-sync activity 5)
 ::
 ++  test-sync-reads-2
-  =+  state-2
+  =+  state-2:sync-reads
   (run-sync-reads pre-sync post-sync activity 5)
 ::
 ++  test-sync-reads-3
-  =+  state-3
+  =+  state-3:sync-reads
   (run-sync-reads pre-sync post-sync activity 9)
 ++  run-sync-reads
   |=  [pre=indices:a post=indices:a =activity:a count=@ud]
@@ -29,445 +29,645 @@
   ;<  *  bind:m  (ex-equal !>(~(wyt by pre)) !>(count))
   ;<  new=vase  bind:m  get-save
   =/  want-indices  post
-  =+  !<(new-state=current-state new)
+  =+  !<(=new-state new)
   =/  new-indices  indices.new-state
   (ex-equal !>(new-indices) !>(want-indices))
 ::
-+$  current-state
-  $:  %5
+++  test-fix-init
+  =+  state-0:fix-init
+  %-  eval-mare
+  =/  m  (mare ,~)
+  ^-  form:m
+  ;<  *  bind:m  (set-scry-gate scries)
+  ;<  *  bind:m  (do-init dap activity-agent)
+  ;<  *  bind:m  (jab-bowl |=(b=bowl b(our ~zod, src ~zod)))
+  =/  start-state  [%6 %some indices pre-fix volumes]
+  ;<  caz=(list card:agent:gall)  bind:m  (do-load activity-agent `!>(start-state))
+  ;<  *  bind:m  (ex-equal !>(~(wyt by pre-fix)) !>(11))
+  =/  cage  noun+!>(%fix-init-unreads)
+  ;<  bowl  bind:m  get-bowl
+  ;<  *  bind:m
+    %+  ex-cards  caz
+    ~[(ex-poke /fix-init-unreads [~zod dap] cage)]
+  ;<  *  bind:m  (do-poke cage)
+  ;<  new=vase  bind:m  get-save
+  =+  !<(=new-state new)
+  (ex-equal !>(activity.new-state) !>(post-fix))
++$  new-state
+  $:  %6
       allowed=notifications-allowed:a
       =indices:a
       =activity:a
       =volume-settings:a
   ==
 +$  index-pair  [=source:a =index:a]
-+$  source-set
-  $:  thrd1=index-pair
-      thrd2=index-pair
-      chnl=index-pair
-      grp=index-pair
-      base=index-pair
-  ==
-::  in this case, we test when a child has unreads before any of the parents,
-::  resulting in a large list of reads and a very early floor
-++  state-0
++$  dms  (map ship dm:ch)
++$  clubs  (map id:club:ch club:ch)
+++  sync-reads
   |%
-  ++  sources
-    ^-  source-set
-    =/  =reads:a
-      :-  d-1
-      %+  gas:on-read-items:a  *read-items:a
-      :~  [d1 ~]
-          [d2 ~]
-          [d3 ~]
-          [d4 ~]
-          [d5 ~]
-      ==
-    =/  thrd1  (thread-source-1 flag nest i0)
-    =/  thrd2  (thread-source-2 flag nest i0)
-    =/  chnl  (channel-source flag nest reads index.thrd1 index.thrd2 i0)
-    =/  grp  (group-source flag index.chnl)
-    :*  thrd1
-        thrd2
-        chnl
-        grp
-        (base-source index.grp)
-    ==
-  ++  pre-sync
-    ^-  indices:a
-    %-  ~(gas by *indices:a)
-    =>  sources
-    .(base [base ~])
-  ++  post-sync
-    ^-  indices:a
-    =+  sources
-    ::  only care about the index
-    %-  my
-    :~  thrd1
-        thrd2
-        chnl(reads.index [d4 ~])
-        grp(reads.index [d-1 ~])
-        base(reads.index [d-1 ~])
+  +$  source-set
+    $:  thrd1=index-pair
+        thrd2=index-pair
+        chnl=index-pair
+        grp=index-pair
+        base=index-pair
     ==
-  ++  activity
-    ^-  activity:a
-    =+  sources
-    =/  chan-sum=activity-summary:a
-      :*  newest=d5
-          count=0
-          notify-count=0
-          notify=|
-          unread=~
-          children=(sy (get-children:src pre-sync source.chnl))
-          reads=[d-1 (my [d1 ~] [d2 ~] [d3 ~] [d4 ~] [d5 ~] ~)]
+  ::  in this case, we test when a child has unreads before any of the parents,
+  ::  resulting in a large list of reads and a very early floor
+  ++  state-0
+    |%
+    ++  sources
+      ^-  source-set
+      =/  =reads:a
+        :-  d-1
+        %+  gas:on-read-items:a  *read-items:a
+        :~  [d1 ~]
+            [d2 ~]
+            [d3 ~]
+            [d4 ~]
+            [d5 ~]
+        ==
+      =/  thrd1  (thread-source-1 flag nest i0)
+      =/  thrd2  (thread-source-2 flag nest i0)
+      =/  chnl
+        %+  merge-children  (channel-source flag nest reads i0)
+        ~[stream.index.thrd1 stream.index.thrd2]
+      =/  grp
+        %+  merge-children  (group-source flag reads.index.chnl)
+        ~[stream.index.chnl]
+      :*  thrd1
+          thrd2
+          chnl
+          grp
+          (merge-children (base-source reads.index.grp) ~[stream.index.grp])
+      ==
+    ++  pre-sync
+      ^-  indices:a
+      %-  ~(gas by *indices:a)
+      =>  sources
+      .(base [base ~])
+    ++  post-sync
+      ^-  indices:a
+      =+  sources
+      ::  only care about the index
+      %-  my
+      :~  thrd1
+          thrd2
+          chnl(reads.index [d4 ~])
+          grp(reads.index [d-1 ~])
+          base(reads.index [d-1 ~])
       ==
-    %-  my
-    :~  :-  source.thrd1
+    ++  activity
+      ^-  activity:a
+      =+  sources
+      =/  chan-sum=activity-summary:a
         :*  newest=d5
-            count=2
-            notify-count=0
-            notify=|
-            unread=`[[[~dev d0] d0] 2 |]
-            children=(sy (get-children:src pre-sync source.thrd1))
-            reads=[d-1 ~]
-        ==
-      ::
-        :-  source.thrd2
-        :*  newest=d2
             count=0
             notify-count=0
             notify=|
             unread=~
-            children=(sy (get-children:src pre-sync source.thrd2))
-            reads=[d2 ~]
+            children=(sy (get-children:src pre-sync source.chnl))
+            reads=[d-1 (my [d1 ~] [d2 ~] [d3 ~] [d4 ~] [d5 ~] ~)]
         ==
-      ::
-        [source.chnl chan-sum]
-      ::
-        :-  source.grp
-        chan-sum(children (sy (get-children:src pre-sync source.grp)))
-      ::
-        :-  source.base
-        chan-sum(children ~)
-    ==
-  --
-::  in this case, we test when a child has unreads later than any of the
-::  parents, but all other children are read, resulting in a late floor
-::  and no reads
-++  state-1
-  |%
-  ++  sources
-    ^-  source-set
-    =/  thrd1  (thread-source-2 flag nest i0)
-    =/  thrd2  (thread-source-3 flag nest i0)
-    =/  =reads:a  [d-1 (my [d1 ~] [d2 ~] [d3 ~] ~)]
-    =/  chnl  (channel-source flag nest reads index.thrd1 index.thrd2 i0)
-    =/  grp  (group-source flag index.chnl)
-    :*  thrd1
-        thrd2
-        chnl
-        grp
-        (base-source index.grp)
-    ==
-  ++  pre-sync
-    ^-  indices:a
-    %-  ~(gas by *indices:a)
-    =>  sources
-    .(base [base ~])
-  ++  post-sync
-    ^-  indices:a
-    =+  sources
-    %-  my
-    :~  thrd1
-        thrd2
-        chnl(reads.index [d3 ~])
-        grp(reads.index [d-1 ~])
-        base(reads.index [d-1 ~])
-    ==
-  ++  activity
-    ^-  activity:a
-    =+  sources
-    =/  chan-sum=activity-summary:a
-      :*  newest=d5
-          count=1
-          notify-count=0
-          notify=|
-          unread=`[[[~dev d4] d4] 1 |]
-          children=(sy (get-children:src pre-sync source.chnl))
-          reads=[d-1 (my [d1 ~] [d2 ~] [d3 ~] ~)]
+      %-  my
+      :~  :-  source.thrd1
+          :*  newest=d5
+              count=2
+              notify-count=0
+              notify=|
+              unread=`[[[~dev d0] d0] 2 |]
+              children=(sy (get-children:src pre-sync source.thrd1))
+              reads=[d-1 ~]
+          ==
+        ::
+          :-  source.thrd2
+          :*  newest=d2
+              count=0
+              notify-count=0
+              notify=|
+              unread=~
+              children=(sy (get-children:src pre-sync source.thrd2))
+              reads=[d2 ~]
+          ==
+        ::
+          [source.chnl chan-sum]
+        ::
+          :-  source.grp
+          chan-sum(children (sy (get-children:src pre-sync source.grp)))
+        ::
+          :-  source.base
+          chan-sum(children ~)
       ==
-    %-  my
-    :~  :-  source.thrd1
-        :*  newest=d2
-            count=0
-            notify-count=0
-            notify=|
-            unread=~
-            children=(sy (get-children:src pre-sync source.thrd1))
-            reads=[d-1 ~]
-        ==
-      ::
-        :-  source.thrd2
+    --
+  ::  in this case, we test when a child has unreads later than any of the
+  ::  parents, but all other children are read, resulting in a late floor
+  ::  and no reads
+  ++  state-1
+    |%
+    ++  sources
+      ^-  source-set
+      =/  thrd1  (thread-source-2 flag nest i0)
+      =/  thrd2  (thread-source-3 flag nest i0)
+      =/  =reads:a  [d-1 (my [d1 ~] [d2 ~] [d3 ~] ~)]
+      =/  chnl
+        %+  merge-children  (channel-source flag nest reads i0)
+        ~[stream.index.thrd1 stream.index.thrd2]
+      =/  grp
+        %+  merge-children  (group-source flag reads.index.chnl)
+        ~[stream.index.chnl]
+      :*  thrd1
+          thrd2
+          chnl
+          grp
+          (merge-children (base-source reads.index.grp) ~[stream.index.grp])
+      ==
+    ++  pre-sync
+      ^-  indices:a
+      %-  ~(gas by *indices:a)
+      =>  sources
+      .(base [base ~])
+    ++  post-sync
+      ^-  indices:a
+      =+  sources
+      %-  my
+      :~  thrd1
+          thrd2
+          chnl(reads.index [d3 ~])
+          grp(reads.index [d-1 ~])
+          base(reads.index [d-1 ~])
+      ==
+    ++  activity
+      ^-  activity:a
+      =+  sources
+      =/  chan-sum=activity-summary:a
         :*  newest=d5
             count=1
             notify-count=0
             notify=|
-            unread=`[[[~dev d5] d5] 1 |]
-            children=(sy (get-children:src pre-sync source.thrd2))
-            reads=[d0 ~]
-        ==
-      ::
-        [source.chnl chan-sum]
-      ::
-        :-  source.grp
-        %=  chan-sum
-          unread  ~
-          children  (sy (get-children:src pre-sync source.grp))
+            unread=`[[[~dev d4] d4] 1 |]
+            children=(sy (get-children:src pre-sync source.chnl))
+            reads=[d-1 (my [d1 ~] [d2 ~] [d3 ~] ~)]
         ==
-      ::
-        :-  source.base
-        %=  chan-sum
-          unread  ~
-          children  ~
-        ==
-    ==
-  --
-::  in this case we test a parent having mixed reads with children that
-::  are all read, resulting in a floor up to the parent reads and one
-::  read item that comes later
-++  state-2
-  |%
-  ++  sources
-    ^-  source-set
-    =/  thrd1  (thread-source-2 flag nest i0)
-    =/  thrd2  (thread-source-3 flag nest i0)
-    =.  thrd2  thrd2(reads.index [d5 ~])
-    =/  =reads:a  [d3 (my [d5 ~] ~)]
-    =/  chnl  (channel-source flag nest reads index.thrd1 index.thrd2 i0)
-    =/  grp  (group-source flag index.chnl)
-    :*  thrd1
-        thrd2
-        chnl
-        grp
-        (base-source index.grp)
-    ==
-  ++  pre-sync
-    ^-  indices:a
-    %-  ~(gas by *indices:a)
-    =>  sources
-    .(base [base ~])
-  ++  post-sync
-    ^-  indices:a
-    =+  sources
-    %-  my
-    :~  thrd1
-        thrd2
-        chnl(reads.index [d3 ~])
-        grp(reads.index [d3 ~])
-        base(reads.index [d3 ~])
-    ==
-  ++  activity
-    ^-  activity:a
-    =+  sources
-    =/  chan-sum=activity-summary:a
-      :*  newest=d5
-          count=1
-          notify-count=0
-          notify=|
-          unread=`[[[~dev d4] d4] 1 |]
-          children=(sy (get-children:src pre-sync source.chnl))
-          reads=[d3 (my [d3 ~] [d5 ~] ~)]
+      %-  my
+      :~  :-  source.thrd1
+          :*  newest=d2
+              count=0
+              notify-count=0
+              notify=|
+              unread=~
+              children=(sy (get-children:src pre-sync source.thrd1))
+              reads=[d-1 ~]
+          ==
+        ::
+          :-  source.thrd2
+          :*  newest=d5
+              count=1
+              notify-count=0
+              notify=|
+              unread=`[[[~dev d5] d5] 1 |]
+              children=(sy (get-children:src pre-sync source.thrd2))
+              reads=[d0 ~]
+          ==
+        ::
+          [source.chnl chan-sum]
+        ::
+          :-  source.grp
+          %=  chan-sum
+            unread  ~
+            children  (sy (get-children:src pre-sync source.grp))
+          ==
+        ::
+          :-  source.base
+          %=  chan-sum
+            unread  ~
+            children  ~
+          ==
       ==
-    %-  my
-    :~  :-  source.thrd1
-        :*  newest=d2
-            count=0
-            notify-count=0
-            notify=|
-            unread=~
-            children=(sy (get-children:src pre-sync source.thrd1))
-            reads=[d2 ~]
-        ==
-      ::
-        :-  source.thrd2
+    --
+  ::  in this case we test a parent having mixed reads with children that
+  ::  are all read, resulting in a floor up to the parent reads and one
+  ::  read item that comes later
+  ++  state-2
+    |%
+    ++  sources
+      ^-  source-set
+      =/  thrd1  (thread-source-2 flag nest i0)
+      =/  thrd2  (thread-source-3 flag nest i0)
+      =.  thrd2  thrd2(reads.index [d5 ~])
+      =/  =reads:a  [d3 (my [d5 ~] ~)]
+      =/  chnl
+        %+  merge-children  (channel-source flag nest reads i0)
+        ~[stream.index.thrd1 stream.index.thrd2]
+      =/  grp
+        %+  merge-children  (group-source flag reads.index.chnl)
+        ~[stream.index.chnl]
+      :*  thrd1
+          thrd2
+          chnl
+          grp
+          (merge-children (base-source reads.index.grp) ~[stream.index.grp])
+      ==
+    ++  pre-sync
+      ^-  indices:a
+      %-  ~(gas by *indices:a)
+      =>  sources
+      .(base [base ~])
+    ++  post-sync
+      ^-  indices:a
+      =+  sources
+      %-  my
+      :~  thrd1
+          thrd2
+          chnl(reads.index [d3 ~])
+          grp(reads.index [d3 ~])
+          base(reads.index [d3 ~])
+      ==
+    ++  activity
+      ^-  activity:a
+      =+  sources
+      =/  chan-sum=activity-summary:a
         :*  newest=d5
-            count=0
+            count=1
             notify-count=0
             notify=|
-            unread=~
-            children=(sy (get-children:src pre-sync source.thrd2))
-            reads=[d0 ~]
+            unread=`[[[~dev d4] d4] 1 |]
+            children=(sy (get-children:src pre-sync source.chnl))
+            reads=[d3 (my [d3 ~] [d5 ~] ~)]
         ==
-      ::
-        [source.chnl chan-sum]
-      ::
-        :-  source.grp
-        %=  chan-sum
-          unread  ~
-          children  (sy (get-children:src pre-sync source.grp))
+      %-  my
+      :~  :-  source.thrd1
+          :*  newest=d2
+              count=0
+              notify-count=0
+              notify=|
+              unread=~
+              children=(sy (get-children:src pre-sync source.thrd1))
+              reads=[d2 ~]
+          ==
+        ::
+          :-  source.thrd2
+          :*  newest=d5
+              count=0
+              notify-count=0
+              notify=|
+              unread=~
+              children=(sy (get-children:src pre-sync source.thrd2))
+              reads=[d0 ~]
+          ==
+        ::
+          [source.chnl chan-sum]
+        ::
+          :-  source.grp
+          %=  chan-sum
+            unread  ~
+            children  (sy (get-children:src pre-sync source.grp))
+          ==
+        ::
+          :-  source.base
+          %=  chan-sum
+            unread  ~
+            children  ~
+          ==
+      ==
+    --
+  ::  in this case we test multiple parents one with mixed reads and one
+  ::  with all reads
+  ++  state-3
+    |%
+    ++  sources
+      =/  thrd1-1  (thread-source-1 flag nest i0)
+      =/  thrd1-2  (thread-source-2 flag nest i0)
+      =/  r1=reads:a
+        :-  d-1
+        %+  gas:on-read-items:a  *read-items:a
+        :~  [d1 ~]
+            [d2 ~]
+            [d3 ~]
+            [d4 ~]
         ==
+      =/  chnl1
+        %+  merge-children  (channel-source flag nest r1 i0)
+        ~[stream.index.thrd1-1 stream.index.thrd1-2]
+      =/  grp1
+        %+  merge-children  (group-source flag reads.index.chnl1)
+        ~[stream.index.chnl1]
       ::
-        :-  source.base
-        %=  chan-sum
-          unread  ~
-          children  ~
-        ==
-    ==
-  --
-::  in this case we test multiple parents one with mixed reads and one
-::  with all reads
-++  state-3
-  |%
-  ++  sources
-    =/  thrd1-1  (thread-source-1 flag nest i0)
-    =/  thrd1-2  (thread-source-2 flag nest i0)
-    =/  r1=reads:a
-      :-  d-1
-      %+  gas:on-read-items:a  *read-items:a
-      :~  [d1 ~]
-          [d2 ~]
-          [d3 ~]
-          [d4 ~]
-      ==
-    =/  chnl1  (channel-source flag nest r1 index.thrd1-1 index.thrd1-2 i0)
-    =/  grp1  (group-source flag index.chnl1)
-    ::
-    =/  second-grp=flag:g  [~dev %urbit]
-    =/  second-chnl=nest:c  [%chat ~dev %lobby]
-    =/  thrd2-1  (thread-source-2 second-grp second-chnl i1)
-    =/  thrd2-2  (thread-source-3 second-grp second-chnl i1)
-    =/  r2=reads:a  [(add d3 i1) ~]
-    =/  chnl2
-      (channel-source second-grp second-chnl r2 index.thrd2-1 index.thrd2-2 i1)
-    =/  grp2  (group-source second-grp index.chnl2)
-    =/  base
-      %-  base-source
-      :*  (uni:on-event:a stream.index.grp1 stream.index.grp2)
-        ::
+      =/  second-grp=flag:g  [~dev %urbit]
+      =/  second-chnl=nest:c  [%chat ~dev %lobby]
+      =/  thrd2-1  (thread-source-2 second-grp second-chnl i1)
+      =/  thrd2-2  (thread-source-3 second-grp second-chnl i1)
+      =/  r2=reads:a  [(add d3 i1) ~]
+      =/  chnl2
+        %+  merge-children  (channel-source second-grp second-chnl r2 i1)
+        ~[stream.index.thrd2-1 stream.index.thrd2-2]
+      =/  grp2
+        %+  merge-children  (group-source second-grp reads.index.chnl2)
+        ~[stream.index.chnl2]
+      =/  base
+        %+  merge-children
+          %-  base-source
           :-  d-1
           %+  gas:on-read-items:a  items.r1
           :~  [(add d1 i1) ~]
               [(add d2 i1) ~]
               [(add d3 i1) ~]
           ==
-        ::
-          *@da
-      ==
-    ::
-    :*  thrd1-1=thrd1-1
-        thrd1-2=thrd1-2
-        thrd2-1=thrd2-1
-        thrd2-2=thrd2-2
-        chnl1=chnl1
-        chnl2=chnl2
-        grp1=grp1
-        grp2=grp2
-        base=base
-    ==
-  ++  pre-sync
-    ^-  indices:a
-    %-  ~(gas by *indices:a)
-    =>  sources
-    .(base [base ~])
-  ++  post-sync
-    ^-  indices:a
-    =+  sources
-    %-  my
-    :~  thrd1-1
-        thrd1-2
-        thrd2-1
-        thrd2-2
-        chnl1(reads.index [d4 ~])
-        chnl2
-        grp1(reads.index [d-1 ~])
-        grp2
-        base(reads.index [d-1 ~])
-    ==
-  ++  activity
-    ^-  activity:a
-    =+  sources
-    =/  chan-sum1=activity-summary:a
-      :*  newest=d5
-          count=0
-          notify-count=0
-          notify=|
-          unread=~
-          children=(sy (get-children:src pre-sync source.chnl1))
-          reads=[d-1 (my [d1 ~] [d2 ~] [d3 ~] [d4 ~] ~)]
+        ~[stream.index.grp1 stream.index.grp2]
+      ::
+      :*  thrd1-1=thrd1-1
+          thrd1-2=thrd1-2
+          thrd2-1=thrd2-1
+          thrd2-2=thrd2-2
+          chnl1=chnl1
+          chnl2=chnl2
+          grp1=grp1
+          grp2=grp2
+          base=base
       ==
-    =/  time-chan2  (add d4 i1)
-    =/  time2-2  (add d5 i1)
-    =/  chan-sum2=activity-summary:a
-      :*  newest=time2-2
-          count=1
-          notify-count=0
-          notify=|
-          unread=`[[[~dev time-chan2] time-chan2] 1 |]
-          children=(sy (get-children:src pre-sync source.chnl2))
-          reads=[(add d3 i1) ~]
+    ++  pre-sync
+      ^-  indices:a
+      %-  ~(gas by *indices:a)
+      =>  sources
+      .(base [base ~])
+    ++  post-sync
+      ^-  indices:a
+      =+  sources
+      %-  my
+      :~  thrd1-1
+          thrd1-2
+          thrd2-1
+          thrd2-2
+          chnl1(reads.index [d4 ~])
+          chnl2
+          grp1(reads.index [d-1 ~])
+          grp2
+          base(reads.index [d-1 ~])
       ==
-    %-  my
-    :~  :-  source.thrd1-1
+    ++  activity
+      ^-  activity:a
+      =+  sources
+      =/  chan-sum1=activity-summary:a
         :*  newest=d5
-            count=2
-            notify-count=0
-            notify=|
-            unread=`[[[~dev d0] d0] 2 |]
-            children=(sy (get-children:src pre-sync source.thrd1-1))
-            reads=[d-1 ~]
-        ==
-      ::
-        :-  source.thrd1-2
-        :*  newest=d2
             count=0
             notify-count=0
             notify=|
             unread=~
-            children=(sy (get-children:src pre-sync source.thrd1-2))
-            reads=[d2 ~]
+            children=(sy (get-children:src pre-sync source.chnl1))
+            reads=[d-1 (my [d1 ~] [d2 ~] [d3 ~] [d4 ~] ~)]
         ==
-      ::
-        :-  source.thrd2-1
-        :*  newest=(add d2 i1)
-            count=0
-            notify-count=0
-            notify=|
-            unread=~
-            children=(sy (get-children:src pre-sync source.thrd2-1))
-            reads=[(add d2 i1) ~]
-        ==
-      ::
-        :-  source.thrd2-2
+      =/  time-chan2  (add d4 i1)
+      =/  time2-2  (add d5 i1)
+      =/  chan-sum2=activity-summary:a
         :*  newest=time2-2
             count=1
             notify-count=0
             notify=|
-            unread=`[[[~dev time2-2] time2-2] 1 |]
-            children=(sy (get-children:src pre-sync source.thrd2-2))
-            reads=[(add d0 i1) ~]
-        ==
-      ::
-        [source.chnl1 chan-sum1]
-        [source.chnl2 chan-sum2]
-      ::
-        :-  source.grp1
-        %=  chan-sum1
-          unread  ~
-          children  (sy (get-children:src pre-sync source.grp1))
-        ==
-      ::
-        :-  source.grp2
-        %=  chan-sum2
-          unread  ~
-          children  (sy (get-children:src pre-sync source.grp2))
-        ==
-      ::
-        :-  source.base
-        %=  chan-sum2
-          unread  ~
-          children  ~
+            unread=`[[[~dev time-chan2] time-chan2] 1 |]
+            children=(sy (get-children:src pre-sync source.chnl2))
+            reads=[(add d3 i1) ~]
         ==
+      %-  my
+      :~  :-  source.thrd1-1
+          :*  newest=d5
+              count=2
+              notify-count=0
+              notify=|
+              unread=`[[[~dev d0] d0] 2 |]
+              children=(sy (get-children:src pre-sync source.thrd1-1))
+              reads=[d-1 ~]
+          ==
+        ::
+          :-  source.thrd1-2
+          :*  newest=d2
+              count=0
+              notify-count=0
+              notify=|
+              unread=~
+              children=(sy (get-children:src pre-sync source.thrd1-2))
+              reads=[d2 ~]
+          ==
+        ::
+          :-  source.thrd2-1
+          :*  newest=(add d2 i1)
+              count=0
+              notify-count=0
+              notify=|
+              unread=~
+              children=(sy (get-children:src pre-sync source.thrd2-1))
+              reads=[(add d2 i1) ~]
+          ==
+        ::
+          :-  source.thrd2-2
+          :*  newest=time2-2
+              count=1
+              notify-count=0
+              notify=|
+              unread=`[[[~dev time2-2] time2-2] 1 |]
+              children=(sy (get-children:src pre-sync source.thrd2-2))
+              reads=[(add d0 i1) ~]
+          ==
+        ::
+          [source.chnl1 chan-sum1]
+          [source.chnl2 chan-sum2]
+        ::
+          :-  source.grp1
+          %=  chan-sum1
+            unread  ~
+            children  (sy (get-children:src pre-sync source.grp1))
+          ==
+        ::
+          :-  source.grp2
+          %=  chan-sum2
+            unread  ~
+            children  (sy (get-children:src pre-sync source.grp2))
+          ==
+        ::
+          :-  source.base
+          %=  chan-sum2
+            unread  ~
+            children  ~
+          ==
+      ==
+    --
+  --
+++  fix-init
+  |%
+  +$  source-set
+    $:  thrd1=index-pair
+        thrd2=index-pair
+        chnl=index-pair
+        bad-chnl-migration=index-pair
+        grp=index-pair
+        dm-thread=index-pair
+        read-dm=index-pair
+        unread-dm=index-pair
+        dm-invite=index-pair
+        bad-dm-migration=index-pair
+        base=index-pair
     ==
+  ::  we want to test multiple scenarios in one go. we have a dm that's
+  ::  completely read, a dm that's unread, and a dm with only an invite.
+  ::  we also have a channel with threads that is completely read.
+  ++  state-0
+    |%
+    ++  sources
+      ^-  source-set
+      =/  thrd1  (thread-source-2 flag nest i0)
+      =/  thrd2  (thread-source-3 flag nest i0)
+      =.  thrd2  thrd2(reads.index [d5 ~])
+      =/  =reads:a  [d4 ~]
+      =/  chnl
+        %+  merge-children  (channel-source flag nest reads i0)
+        ~[stream.index.thrd1 stream.index.thrd2]
+      =/  bad-chnl=index-pair
+        :-  [%channel [%chat ~syx %hi] flag]
+        :_  [[d0 ~] d0]
+        %+  gas:on-event:a  *stream:a
+        ~[[d1 [[%chan-init [%chat ~syx %hi] flag] | |]]]
+      =/  grp
+        %+  merge-children  (group-source flag reads)
+        ~[stream.index.chnl stream.index.bad-chnl]
+      =/  dm-thread  (dm-thread-source [[~dev d0] d0] [%ship ~rus])
+      =/  read-dm
+        %+  merge-children  (dm-source [%ship ~rus] [d3 ~])
+        ~[stream.index.dm-thread]
+      =/  unread-dm
+        (dm-source [%ship ~dyl] [d0 ~])
+      =/  dm-invite=index-pair
+        :-  [%dm [%club 0v1d.u717i.b92pp.aa9oh.u044i.joqln]]
+        :_  [[d0 ~] d0]
+        %+  gas:on-event:a  *stream:a
+        ~[[d1 [[%dm-invite [%club 0v1d.u717i.b92pp.aa9oh.u044i.joqln]] & |]]]
+      =/  bad-dm-migration=index-pair
+        :-  [%dm [%ship ~syx]]
+        :_  [[d0 ~] d0]
+        %+  gas:on-event:a  *stream:a
+        ~[[d1 [[%dm-invite [%ship ~syx]] & |]]]
+      :*  thrd1
+          thrd2
+          chnl
+          bad-chnl
+          grp
+          dm-thread
+          read-dm
+          unread-dm
+          dm-invite
+          bad-dm-migration
+          %+  merge-children  (base-source [d0 ~])
+          :~  stream.index.grp
+              stream.index.read-dm
+              stream.index.unread-dm
+              stream.index.dm-invite
+              stream.index.bad-dm-migration
+          ==
+      ==
+    ++  scries
+      |=  =path
+      ^-  (unit vase)
+      ?+  path  ~
+        [%gx @ %chat @ %full *]   `!>(chat-scry)
+        [%gx @ %channels @ %v2 %channels %full *]   `!>(channels-scry)
+      ==
+    ++  channels-scry
+      ^-  channels:c
+      =+  sources
+      =|  empty=channel:c
+      %-  ~(gas by *channels:c)
+      :~  :-  (get-nest source.chnl)
+          empty(remark [d5 d4 & ~])
+          :-  (get-nest source.bad-chnl-migration)
+          empty(remark [d1 d1 & ~])
+      ==
+    ++  chat-scry
+      ^-  [dms clubs]
+      =+  sources
+      =|  empty-club=club:ch
+      =|  empty-dm=dm:ch
+      =/  =dms
+        %-  ~(gas by *dms)
+        :~  :-  (get-ship source.read-dm)
+            empty-dm(remark [d4 d3 & ~])
+            :-  (get-ship source.unread-dm)
+            empty-dm(remark [d3 d0 & ~])
+            :-  (get-ship source.bad-dm-migration)
+            empty-dm(remark [d1 d1 & ~])
+        ==
+      =/  =clubs
+        %+  ~(put by *clubs)  (get-club source.dm-invite)
+        empty-club(remark [d0 d0 & ~])
+      [dms clubs]
+    ++  get-nest
+      |=  =source:a
+      ^-  nest:c
+      ?>  ?=(%channel -.source)
+      nest.source
+    ++  get-ship
+      |=  =source:a
+      ^-  ship
+      ?>  ?=(%dm -.source)
+      ?>  ?=(%ship -.whom.source)
+      p.whom.source
+    ++  get-club
+      |=  =source:a
+      ^-  id:club:ch
+      ?>  ?=(%dm -.source)
+      ?>  ?=(%club -.whom.source)
+      p.whom.source
+    ++  volumes
+      %+  roll
+        ~(tap by indices)
+      |=  [[=source:a =index:a] =volume-settings:a]
+      %+  ~(put by volume-settings)  source
+      default-volumes:a
+    ++  indices
+      %-  ~(gas by *indices:a)
+      =>  sources
+      .(base [base ~])
+    ++  pre-fix
+      ^-  activity:a
+      %+  roll
+        ~(tap by indices)
+      |=  [[=source:a =index:a] =activity:a]
+      %+  ~(put by activity)  source
+      (~(summarize-unreads urd indices *activity:a volumes fake-log) source index)
+    ++  post-fix
+      ^-  activity:a
+      =+  sources
+      %-  ~(uni by pre-fix)
+      %-  ~(gas by *activity:a)
+      :~  :-  source.bad-chnl-migration
+          [d1 0 0 | ~ ~ ~]
+          :-  source.chnl
+          [d5 0 0 | ~ (sy source.thrd1 source.thrd2 ~) ~]
+          :-  source.grp
+          [d5 0 0 | ~ (sy source.chnl source.bad-chnl-migration ~) ~]
+          :-  source.read-dm
+          [d4 0 0 | ~ (sy source.dm-thread ~) ~]
+          :-  source.bad-dm-migration
+          [d1 0 0 | ~ ~ ~]
+          :-  source.base
+          [d5 2 1 & ~ ~ ~]
+      ==
+    --
   --
 ::  base
 ++  base-source
-  |=  group-idx=index:a
+  |=  =reads:a
   ^-  index-pair
   :-  [%base ~]
-  group-idx(stream (child-stream stream.group-idx))
+  [*stream:a reads d0]
 ::  the group has no posts of its own only from children, it is "unread"
 ++  group-source
-  |=  [=flag:g channel-idx=index:a]
+  |=  [=flag:g =reads:a]
   ^-  index-pair
   :-  [%group flag]
-  channel-idx(stream (child-stream stream.channel-idx))
+  [*stream:a reads d0]
 ::  the channel only has two posts, and it is completely read
 ++  channel-source
-  |=  [=flag:g =nest:c =reads:a thrd1=index:a thrd2=index:a interval=@dr]
+  |=  [=flag:g =nest:c =reads:a interval=@dr]
   ^-  index-pair
   :-  [%channel nest flag]
-  :*  %+  uni:on-event:a  (child-stream stream.thrd1)
-      %+  gas:on-event:a  (child-stream stream.thrd2)
+  :*  %+  gas:on-event:a  *stream:a
       =/  key1  (mod [[~dev d3] d3] interval)
       =/  key2  (mod [[~dev d4] d4] interval)
       :~  [time.key1 [[%post key1 nest flag *story:c |] | |]]
@@ -476,7 +676,16 @@
     ::
       reads
     ::
-      *@da
+      d0
+  ==
+++  dm-source
+  |=  [=whom:ch =reads:a]
+  ^-  index-pair
+  :-  [%dm whom]
+  :_  [reads d0]
+  %+  gas:on-event:a  *stream:a
+  :~  [d2 [[%dm-post [[~rus d2] d2] whom *story:c |] | |]]
+      [d3 [[%dm-post [[~rus d3] d3] whom *story:c |] | |]]
   ==
 ::
 ::  this thread has two messages and is unread
@@ -521,6 +730,15 @@
     ::
       *@da
   ==
+++  dm-thread-source
+  |=  [parent=message-key:a =whom:ch]
+  ^-  index-pair
+  :-  [%dm-thread parent whom]
+  :_  [[d4 ~] d0]
+  %+  gas:on-event:a  *stream:a
+  :~  [d4 [[%dm-reply [[~rus d4] d4] parent whom *story:c |] | |]]
+      [d1 [[%dm-reply [[~rus d1] d1] parent whom *story:c |] | |]]
+  ==
 ++  create-reply-pair
   |=  [key=message-key:a parent=message-key:a interval=@dr]
   =.  key  (mod key interval)
@@ -528,9 +746,24 @@
 ++  mod
   |=  [key=message-key:a interval=@dr]
   key(time (add time.key interval), q.id (add q.id.key interval))
+++  merge-children
+  |=  [index-pair children=(list stream:a)]
+  ^-  index-pair
+  :-  source
+  %=  index
+      stream
+    %+  roll
+      children
+    |=  [=stream:a acc=_stream.index]
+    (uni:on-event:a acc (child-stream stream))
+  ==
 ++  child-stream
   |=  =stream:a
   (run:on-event:a stream |=(=event:a event(child &)))
+++  fake-log
+  |=  msg=(trap tape)
+  same
+  :: (slog leaf+"%activity {(msg)}" ~)
 ++  i0  *@dr
 ++  i1  (add i0 ~s1)
 ++  d-1  (dec *@da)