::  graph-store [landscape]
::
/+  store=graph-store, sigs=signatures, res=resource, default-agent, dbug, verb
~%  %graph-store-top  ..part  ~
|%
+$  card  card:agent:gall
+$  versioned-state
  $%  [%0 *]
      [%1 *]
      [%2 network:zero:store]
      [%3 network:one:store]
      [%4 network:store]
      state-5
  ==
::
+$  state-5  [%5 network:store]
++  orm      orm:store
++  orm-log  orm-log:store
--
::
=|  state-5
=*  state  -
::
%-  agent:dbug
%+  verb  |
^-  agent:gall
~%  %graph-store-agent  ..card  ~
|_  =bowl:gall
+*  this  .
    def   ~(. (default-agent this %|) bowl)
::
++  on-init  [~ this]
++  on-save  !>(state)
++  on-load
  |=  =old=vase
  ^-  (quip card _this)
  =+  !<(old=versioned-state old-vase)
  =|  cards=(list card)
  |-
  ?-    -.old
    %0  !!
    %1  !!
  ::
      %2
    =*  upg  upgrade:store
    %_  $
      -.old            %3
      update-logs.old  (~(run by update-logs.old) update-log-to-one:upg)
      graphs.old       (~(run by graphs.old) marked-graph-to-one:upg)
      archive.old      (~(run by archive.old) marked-graph-to-one:upg)
    ==
  ::
      %3
    =*  upg  upgrade:store
    %_  $
      -.old  %4
      graphs.old       (~(run by graphs.old) marked-graph-to-two:upg)
      archive.old      (~(run by archive.old) marked-graph-to-two:upg)
      tag-queries.old  *tag-queries:store
      validators.old   ~
    ::
        update-logs.old
      %-  ~(run by update-logs.old)
      |=(a=* *update-log:store)
    ==
  ::
      %4
    %_   $
      -.old  %5
    ::
        update-logs.old
      %-  ~(gas by *update-logs:store)
      %+  turn  ~(tap by graphs.old)
      |=  [=resource:store =graph:store mar=(unit mark)]
      :-  resource
      =/  log  (~(got by update-logs.old) resource)
      ?.  =(~ log)  log
      =/  =logged-update:store
        [now.bowl %add-graph resource graph mar %.y]
      (gas:orm-log ~ [now.bowl logged-update] ~)
    ==
  ::
    %5  [cards this(state old)]
  ==
::
++  on-watch
  ~/  %graph-store-watch
  |=  =path
  ^-  (quip card _this)
  |^
  ?>  (team:title our.bowl src.bowl)
  =/  cards=(list card)
    ?+  path       (on-watch:def path)
        [%updates ~]   ~
        [%keys ~]      (give [%keys ~(key by graphs)])
        [%tags ~]      (give [%tags ~(key by tag-queries)])
    ==
  [cards this]
  ::
  ++  give
    |=  =action:store
    ^-  (list card)
    [%give %fact ~ [%graph-update-2 !>(`update:store`[now.bowl action])]]~
  --
::
++  on-poke
  ~/  %graph-store-poke
  |=  [=mark =vase]
  ^-  (quip card _this)
  |^
  ?>  (team:title our.bowl src.bowl)
  =^  cards  state
    ?+  mark           (on-poke:def mark vase)
      %graph-update-2  (graph-update !<(update:store vase))
      %import          (poke-import q.vase)
    ==
  [cards this]
  ::
  ++  graph-update
    |=  =update:store
    ^-  (quip card _state)
    |^
    =?  p.update  =(p.update *time)  now.bowl
    ?-  -.q.update
        %add-graph          (add-graph p.update +.q.update)
        %remove-graph       (remove-graph +.q.update)
        %add-nodes          (add-nodes p.update +.q.update)
        %remove-posts       (remove-posts p.update +.q.update)
        %add-signatures     (add-signatures p.update +.q.update)
        %remove-signatures  (remove-signatures p.update +.q.update)
        %add-tag            (add-tag +.q.update)
        %remove-tag         (remove-tag +.q.update)
        %archive-graph      (archive-graph +.q.update)
        %unarchive-graph    (unarchive-graph +.q.update)
        %run-updates        (run-updates +.q.update)
        %keys               ~|('cannot send %keys as poke' !!)
        %tags               ~|('cannot send %tags as poke' !!)
        %tag-queries        ~|('cannot send %tag-queries as poke' !!)
    ==
    ::
    ++  add-graph
      |=  $:  =time
              =resource:store
              =graph:store
              mark=(unit mark:store)
              overwrite=?
          ==
      ^-  (quip card _state)
      ?>  ?|  overwrite
              ?&  !(~(has by archive) resource)
                  !(~(has by graphs) resource)
          ==  ==
      ~|  "validation of graph {<resource>} failed using mark {<mark>}"
      =^  is-valid  state
        (validate-graph graph mark)
      ?>  is-valid
      =/  =logged-update:store
        [time %add-graph resource graph mark overwrite]
      =/  =update-log:store
        (gas:orm-log ~ [time logged-update] ~)
      :_  %_  state
              graphs       (~(put by graphs) resource [graph mark])
              update-logs  (~(put by update-logs) resource update-log)
              archive      (~(del by archive) resource)
          ==
      %-  zing
      :~  (give [/keys ~] %keys (~(put in ~(key by graphs)) resource))
          (give [/updates ~] %add-graph resource ~ mark overwrite)
      ==
    ::
    ++  remove-graph
      |=  =resource:store
      ^-  (quip card _state)
      ?<  (~(has by archive) resource)
      ?>  (~(has by graphs) resource)
      :-  (give [/updates /keys ~] [%remove-graph resource])
      %_  state
          graphs       (~(del by graphs) resource)
          update-logs  (~(del by update-logs) resource)
      ==
    ::
    ++  add-nodes
      |=  [=time =resource:store nodes=(map index:store node:store)]
      ^-  (quip card _state)
      |^
      =/  [=graph:store mark=(unit mark:store)]
        (~(got by graphs) resource)
      ~|  "cannot add duplicate nodes to {<resource>}"
      ?<  (check-for-duplicates graph ~(key by nodes))
      ~|  "validation of nodes failed using mark {<mark>}"
      =^  is-valid  state
        (check-validity ~(tap by nodes) mark)
      ?>  is-valid
      =/  =update-log:store  (~(got by update-logs) resource)
      =.  update-log
        (put:orm-log update-log time [time [%add-nodes resource nodes]])
      ::
      :-  (give [/updates]~ [%add-nodes resource nodes])
      %_  state
          update-logs  (~(put by update-logs) resource update-log)
          graphs
        %+  ~(put by graphs)
          resource
        :_  mark
        (add-node-list resource graph mark (sort-nodes nodes))
      ==
      ::
      ++  check-validity
        |=  [lis=(list (pair index:store node:store)) mark=(unit ^mark)]
        ^-  [? _state]
        |-
        ?~  lis  [& state]
        =^  is-valid  state
          (validate-graph (gas:orm ~ [(rear p.i.lis) q.i.lis]~) mark)
        ?.  is-valid
          [| state]
        $(lis t.lis)
      ::
      ++  check-for-duplicates
        |=  [=graph:store nodes=(set index:store)]
        ^-  ?
        |^
        %+  lien  ~(tap in nodes)
        |=  =index:store
        (has-node graph index)
        ::
        ++  has-node
          |=  [=graph:store =index:store]
          ^-  ?
          =/  node=(unit node:store)  ~
          |-
          ?~  index
            ?=(^ node)
          ?~  t.index
            (has:orm graph i.index)
          =.  node  (get:orm graph i.index)
          ?~  node  %.n
          ?-  -.children.u.node
              %empty  %.n
              %graph  $(graph p.children.u.node, index t.index)
          ==
        --
      ::
      ++  sort-nodes
        |=  nodes=(map index:store node:store)
        ^-  (list [index:store node:store])
        %+  sort  ~(tap by nodes)
        |=  [p=[=index:store *] q=[=index:store *]]
        ^-  ?
        (lth (lent index.p) (lent index.q))
      ::
      ++  add-node-list
        |=  $:  =resource:store
                =graph:store
                mark=(unit mark:store)
                node-list=(list [index:store node:store])
            ==
        ^-  graph:store
        ?~  node-list  graph
        =*  index  -.i.node-list
        =*  node   +.i.node-list
        ~|  "cannot add deleted post"
        ?>  ?=(%& -.post.node)
        =*  p  p.post.node
        ~|  "graph indexes must match"
        ?>  =(index index.p)
        %_  $
            node-list  t.node-list
            graph      (add-node-at-index graph index node mark)
        ==
      ::
      ++  add-node-at-index
        =|  parent-hash=(unit hash:store)
        |=  $:  =graph:store
                =index:store
                =node:store
                mark=(unit mark:store)
            ==
        ^-  graph:store
        ?<  ?=(~ index)
        =*  atom   i.index
        %^  put:orm
            graph
          atom
        ::  add child
        ::
        ?~  t.index
          ~|  "cannot add deleted post"
          ?>  ?=(%& -.post.node)
          =*  p  p.post.node
          ?~  hash.p
            node(signatures.p.post ~)
          =/  =validated-portion:store
            [parent-hash author.p time-sent.p contents.p]
          =/  =hash:store  `@ux`(sham validated-portion)
          ~|  "hash of post does not match calculated hash"
          ?>  =(hash u.hash.p)
          ~|  "signatures do not match the calculated hash"
          ?>  (are-signatures-valid:sigs our.bowl signatures.p hash now.bowl)
          node
        ::  recurse children
        ::
        =/  parent=node:store
          ~|  "index does not exist to add a node to!"
          (got:orm graph atom)
        %_  parent
            children
          ^-  internal-graph:store
          :-  %graph
          %_  $
            index  t.index
          ::
              parent-hash
            ?:  ?=(%| -.post.parent)
              `p.post.parent
            hash.p.post.parent
          ::
              graph
            ?.  ?=(%graph -.children.parent)
              ~
            p.children.parent
          ==
        ==
      --
    ::
    ++  remove-posts
      |=  [=time =resource:store indices=(set index:store)]
      ^-  (quip card _state)
      |^
      =/  [=graph:store mark=(unit mark:store)]
        (~(got by graphs) resource)
      =/  =update-log:store  (~(got by update-logs) resource)
      =.  update-log
        (put:orm-log update-log time [time [%remove-posts resource indices]])
      :-  (give [/updates]~ [%remove-posts resource indices])
      %_  state
        update-logs  (~(put by update-logs) resource update-log)
      ::
          graphs
        %+  ~(put by graphs)
          resource
        :_  mark
        %^  remove-indices
            resource
          graph
        (sort ~(tap in indices) by-lent)
      ==
      ::
      ++  by-lent
        |*  [a=(list) b=(list)]
        ^-  ?
        (gth (lent a) (lent b))
      ::
      ++  remove-indices
        |=  [=resource:store =graph:store indices=(list index:store)]
        ^-  graph:store
        ?~  indices  graph
        %_  $
          indices  t.indices
          graph    (remove-index graph i.indices)
        ==
      ::
      ++  remove-index
        =|  parent-hash=(unit hash:store)
        |=  [=graph:store =index:store]
        ^-  graph:store
        ?~  index  graph
        =*  atom   i.index
        %^  put:orm
            graph
          atom
        ::  last index in list
        ::
        ?~  t.index
          =/  =node:store
            ~|  "cannot remove index that does not exist {<index>}"
            (got:orm graph atom)
          %_    node
              post
            ~|  "cannot remove post that has already been removed"
            ?>  ?=(%& -.post.node)
            =*  p  p.post.node
            ^-  maybe-post:store
            :-  %|
            ?~  hash.p
              =/  =validated-portion:store
                [parent-hash author.p time-sent.p contents.p]
              `@ux`(sham validated-portion)
            u.hash.p
          ==
        ::  recurse children
        ::
        =/  parent=node:store
          ~|  "parent index does not exist to remove a node from!"
          (got:orm graph atom)
        ~|  "child index does not exist to remove a node from!"
        ?>  ?=(%graph -.children.parent)
        %_    parent
            p.children
          %_  $
            index  t.index
            graph  p.children.parent
          ::
              parent-hash
            ?:  ?=(%| -.post.parent)
              `p.post.parent
            hash.p.post.parent
          ==
        ==
      --
    ::
    ++  add-signatures
      |=  [=time =uid:store =signatures:store]
      ^-  (quip card _state)
      |^
      =*  resource  resource.uid
      =/  [=graph:store mark=(unit mark:store)]
        (~(got by graphs) resource)
      =/  =update-log:store  (~(got by update-logs) resource)
      =.  update-log
        (put:orm-log update-log time [time [%add-signatures uid signatures]])
      ::
      :-  (give [/updates]~ [%add-signatures uid signatures])
      %_  state
          update-logs  (~(put by update-logs) resource update-log)
          graphs
        %+  ~(put by graphs)  resource
        [(add-at-index graph index.uid signatures) mark]
      ==
      ::
      ++  add-at-index
        |=  [=graph:store =index:store =signatures:store]
        ^-  graph:store
        ?~  index  graph
        =*  atom   i.index
        =/  =node:store
          ~|  "node does not exist to add signatures to!"
          (got:orm graph atom)
        ::  last index in list
        ::
        %^  put:orm
            graph
          atom
        ?~  t.index
          ~|  "cannot add signatures to a deleted post"
          ?>  ?=(%& -.post.node)
          ~|  "cannot add signatures to a node missing a hash"
          ?>  ?=(^ hash.p.post.node)
          ~|  "signatures did not match public keys!"
          ?>  %:  are-signatures-valid:sigs
                our.bowl  signatures
                u.hash.p.post.node  now.bowl
              ==
          node(signatures.p.post (~(uni in signatures) signatures.p.post.node))
        ~|  "child graph does not exist to add signatures to!"
        ?>  ?=(%graph -.children.node)
        node(p.children $(graph p.children.node, index t.index))
      --
    ::
    ++  remove-signatures
      |=  [=time =uid:store =signatures:store]
      ^-  (quip card _state)
      |^
      =*  resource  resource.uid
      =/  [=graph:store mark=(unit mark:store)]
        (~(got by graphs) resource)
      =/  =update-log:store  (~(got by update-logs) resource)
      =.  update-log
        %^  put:orm-log  update-log
          time
        [time [%remove-signatures uid signatures]]
      ::
      :-  (give [/updates]~ [%remove-signatures uid signatures])
      %_  state
          update-logs  (~(put by update-logs) resource update-log)
          graphs
        %+  ~(put by graphs)  resource
        [(remove-at-index graph index.uid signatures) mark]
      ==
      ::
      ++  remove-at-index
        |=  [=graph:store =index:store =signatures:store]
        ^-  graph:store
        ?~  index  graph
        =*  atom   i.index
        =/  =node:store
          ~|  "node does not exist to add signatures to!"
          (got:orm graph atom)
        ::  last index in list
        ::
        %^  put:orm
            graph
          atom
        ?~  t.index
          ~|  "cannot add signatures to a deleted post"
          ?>  ?=(%& -.post.node)
          node(signatures.p.post (~(dif in signatures) signatures.p.post.node))
        ~|  "child graph does not exist to add signatures to!"
        ?>  ?=(%graph -.children.node)
        node(p.children $(graph p.children.node, index t.index))
      --
    ::
    ++  add-tag
      |=  [=term =uid:store]
      ^-  (quip card _state)
      ?>  (~(has by graphs) resource.uid)
      :-  (give [/updates /tags ~] [%add-tag term uid])
      %_  state
          tag-queries  (~(put ju tag-queries) term uid)
      ==
    ::
    ++  remove-tag
      |=  [=term =uid:store]
      ^-  (quip card _state)
      :-  (give [/updates /tags ~] [%remove-tag term uid])
      %_  state
          tag-queries  (~(del ju tag-queries) term uid)
      ==
    ::
    ++  archive-graph
      |=  =resource:store
      ^-  (quip card _state)
      ?<  (~(has by archive) resource)
      ?>  (~(has by graphs) resource)
      :-  (give [/updates /keys /tags ~] [%archive-graph resource])
      %_  state
          archive      (~(put by archive) resource (~(got by graphs) resource))
          graphs       (~(del by graphs) resource)
          update-logs  (~(del by update-logs) resource)
      ==
    ::
    ++  unarchive-graph
      |=  =resource:store
      ^-  (quip card _state)
      ?>  (~(has by archive) resource)
      ?<  (~(has by graphs) resource)
      :-  (give [/updates /keys ~] [%unarchive-graph resource])
      %_  state
          archive      (~(del by archive) resource)
          graphs       (~(put by graphs) resource (~(got by archive) resource))
          update-logs  (~(put by update-logs) resource ~)
      ==
    ::
    ++  run-updates
      |=  [=resource:store =update-log:store]
      ^-  (quip card _state)
      ?<  (~(has by archive) resource)
      ?>  (~(has by graphs) resource)
      =/  updates=(list [=time upd=logged-update:store])
        ::  updates are time-ordered with most recent first
        ::  process with earliest first
        (bap:orm-log update-log)
      =|  cards=(list card)
      |-  ^-  (quip card _state)
      ?~  updates
        [cards state]
      =*  update  upd.i.updates
      =^  crds  state
        %-  graph-update
        ^-  update:store
        ?-  -.q.update
          %add-graph          update(resource.q resource)
          %add-nodes          update(resource.q resource)
          %remove-posts       update(resource.q resource)
          %add-signatures     update(resource.uid.q resource)
          %remove-signatures  update(resource.uid.q resource)
        ==
      $(cards (weld cards crds), updates t.updates)
    ::
    ++  give
      |=  [paths=(list path) update=action:store]
      ^-  (list card)
      [%give %fact paths [%graph-update-2 !>(`update:store`[now.bowl update])]]~
    --
  ::
  ++  validate-graph
    |=  [=graph:store mark=(unit mark:store)]
    ^-  [? _state]
    ?~  mark
      [%.y state]
    =/  validate=$-(indexed-post:store indexed-post:store)
      .^  $-(indexed-post:store indexed-post:store)
          %cf
          (scot %p our.bowl)
          q.byk.bowl
          (scot %da now.bowl)
          u.mark
          %graph-indexed-post
          ~
      ==
    :_  state
    |-  ^-  ?
    ?~  graph  %.y
    %+  all:orm  graph
    |=  [=atom =node:store]
    ^-  ?
    ?&  ?|  ?=(%| -.post.node)
            ?=(^ (validate [atom p.post.node]))
        ==
      ::
        ?-  -.children.node
          %empty  %.y
          %graph  ^$(graph p.children.node)
    ==  ==
  ::
  ++  poke-import
    |=  arc=*
    ^-  (quip card _state)
    =^  cards  state
      (import:store arc our.bowl)
    [cards state]
  --
::
++  on-peek
  ~/  %graph-store-peek
  |=  =path
  ^-  (unit (unit cage))
  ?+    path  (on-peek:def path)
    [%x %export ~]  ``noun+!>(state)
  ::
      [%x %keys ~]
    :-  ~  :-  ~  :-  %graph-update-2
    !>(`update:store`[now.bowl [%keys ~(key by graphs)]])
  ::
      [%x %tag-queries *]
    :-  ~  :-  ~  :-  %graph-update-2
    !>  ^-  update:store
    :-  now.bowl
    ?+  t.t.path  (on-peek:def path)
      ~          [%tag-queries tag-queries]
      [%tags ~]  [%tags ~(key by tag-queries)]
    ==
  ::
      [%x %archive @ @ ~]
    =/  =ship   (slav %p i.t.t.path)
    =/  =term   i.t.t.t.path
    =/  marked-graph=(unit marked-graph:store)
      (~(get by graphs) [ship term])
    ?~  marked-graph  [~ ~]
    =*  graph  p.u.marked-graph
    =*  mark   q.u.marked-graph
    :-  ~  :-  ~  :-  %graph-update-2
    !>(`update:store`[now.bowl [%add-graph [ship term] graph mark %.y]])
  ::
      [%x %update-log @ @ *]
    =/  =ship   (slav %p i.t.t.path)
    =/  =term   i.t.t.t.path
    =/  update-log
      (~(get by update-logs) [ship term])
    ?~  update-log  [~ ~]
    :-  ~  :-  ~  :-  %noun
    !>
    ?+    t.t.t.t.path  (on-peek:def path)
      ~  `update-log:store`u.update-log
    ::
        [%latest ~]
      ^-  (unit time)
      %+  biff  update-log
      |=  =update-log:store
      (bind (pry:orm-log:store update-log) head)
    ::
        [%subset @ @ ~]
      ^-  update-log:store
      =*  start  i.t.t.t.t.t.path
      =*  end    i.t.t.t.t.t.t.path
      %^  lot:orm-log
          u.update-log
        (slaw %da start)
      (slaw %da end)
    ==
  ::
      [%x %graph @ @ *]
    =/  =ship   (slav %p i.t.t.path)
    =/  =term   i.t.t.t.path
    =/  marked-graph=(unit marked-graph:store)
      (~(get by graphs) [ship term])
    ?~  marked-graph  [~ ~]
    =*  graph  p.u.marked-graph
    =*  mark   q.u.marked-graph
    ?+    t.t.t.t.path  (on-peek:def path)
        ~  
      :-  ~  :-  ~  :-  %graph-update-2
      !>(`update:store`[now.bowl [%add-graph [ship term] graph mark %.y]])
    ::
        [%mark ~]
      ``noun+!>(`(unit ^mark)`mark)
    ::
        [%subset ?(%lone %kith) @ @ ~]
      =/  start=(unit atom)  (rush i.t.t.t.t.t.t.path dem:ag)
      =/  end=(unit atom)    (rush i.t.t.t.t.t.t.t.path dem:ag)
      :-  ~  :-  ~  :-  %graph-update-2
      !>  ^-  update:store
      :^  now.bowl  %add-nodes  [ship term]
      %-  ~(gas by *(map index:store node:store))
      %+  turn  (tap:orm (lot:orm graph start end))
      |=  [=atom =node:store]
      ^-  [index:store node:store]
      :-  atom^~
      ?:  ?=(%kith i.t.t.t.t.t.path)
        node
      node(children [%empty ~])
    ::
        [%node *]
      |^
      =*    pax  t.t.t.t.t.path
      ?+    pax  (on-peek:def path)
          [%exists ^]
        =/  =index:store
          (turn t.pax (cury slav %ud))
        =/  node  (get-node graph index)
        ``noun+!>(`?`?=(^ node))
      ::
          [%index ?(%lone %kith) ^]
        =/  =index:store
          (turn t.t.pax (cury slav %ud))
        =/  node  (get-node graph index)
        ?~  node  [~ ~]
        :-  ~  :-  ~  :-  %graph-update-2
        !>  ^-  update:store
        :^  now.bowl  %add-nodes  [ship term]
        %-  ~(gas by *(map index:store node:store))
        :_  ~  :-  index
        ?:  ?=(%kith i.t.pax)  u.node
        u.node(children [%empty ~])
      ::
          [%children ?(%lone %kith) @ @ *]
        =/  start=(unit atom)  (rush i.t.t.path dem:ag)
        =/  end=(unit atom)    (rush i.t.t.t.path dem:ag)
        =/  =index:store
          (turn t.t.t.t.pax (cury slav %ud))
        =/  node  (get-node graph index)
        ?:  ?&  ?=(~ node)
                ?=(^ index)
            ==
          [~ ~]
        =/  children=graph:store
          ?~  node
            graph
          ?:  ?=(%empty -.children.u.node)
            ~
          p.children.u.node
        :-  ~  :-  ~  :-  %graph-update-2
        !>  ^-  update:store
        :^  now.bowl  %add-nodes  [ship term]
        %-  ~(gas by *(map index:store node:store))
        %+  turn  (tap:orm (lot:orm children end start))
        |=  [=atom =node:store]
        ^-  [index:store node:store]
        :-  (snoc index atom)
        ?:  ?=(%kith i.t.pax)  node
        node(children [%empty ~])
      ::
          [%siblings ?(%older %newer %oldest %newest) ?(%lone %kith) @ *]
        =/  count  (slav %ud i.t.t.t.pax)
        =/  =index:store
          (turn t.t.t.t.pax (cury slav %ud))
        =/  parent=index:store  (snip index)
        =/  node
          (get-node graph ?:(?=(?(%oldest %newest) i.t.pax) index parent))
        =/  children=graph:store
          ?~  node
            graph
          ?:  ?=(%empty -.children.u.node)
            ~
          p.children.u.node
        :-  ~  :-  ~  :-  %graph-update-2
        !>  ^-  update:store
        :^  now.bowl  %add-nodes  [ship term]
        %-  ~(gas by *(map index:store node:store))
        %+  turn
          ?-    i.t.pax
            %oldest  (scag count (bap:orm children))
            %older   (tab:orm children `(rear index) count)
            %newest  (scag count (tap:orm children))
          ::
              %newer
            %+  slag  (safe-sub (lent -) count)
            (tap:orm (lot:orm children ~ `(rear index)))
          ==
        |=  [=atom =node:store]
        ^-  [index:store node:store]
        :-  %-  snoc
            :_  atom
            ?:(?=(?(%newest %oldest) i.t.pax) index parent)
        ?:  ?=(%kith i.t.t.pax)  node
        node(children [%empty ~])
      ::
          [%firstborn ^]
        |^
        =/  =index:store
          (turn t.pax (cury slav %ud))
        %-  (bond |.(`(unit (unit cage))`[~ ~]))
        %+  biff
          (collect-parents graph index)
        (corl some collect-firstborn)
        ::
        ++  collect-parents
          |=  [=graph:store =index:store]
          ^-  (unit [node:store index:store (map index:store node:store)])
          =|  =(map index:store node:store)
          =|  =node:store
          =|  ind=index:store
          =/  len  (lent index)
          |-
          ?:  (gte (lent ind) len)
            `[node ind map]
          ?>  ?=(^ index)
          =*  atom  i.index
          ?.  (has:orm graph atom)
            ~
          =:  node   (got:orm graph atom)
              ind    (snoc ind atom)
            ==
          ?:  ?=(%empty -.children.node)
            ?.  (gte (lent ind) len)
              ~
            `[node ind (~(put by map) ind node)]
          %_  $
            index  t.index
            graph  p.children.node
            map    (~(put by map) ind node(children empty+~))
          ==
        ::
        ++  collect-firstborn
          |=  [=node:store =index:store =(map index:store node:store)]
          ^-  (unit (unit cage))
          ?:  ?=(%empty -.children.node)
            :-  ~  :-  ~  :-  %graph-update-2
            !>(`update:store`[now.bowl [%add-nodes [ship term] map]])
          =/  item=[k=atom v=node:store]
            (need (ram:orm p.children.node))
          =.  index  (snoc index k.item)
          $(map (~(put by map) index v.item(children empty+~)), node v.item)
        --
      ==
      ::
      ++  get-node
        |=  [=graph:store =index:store]
        ^-  (unit node:store)
        =|  node=(unit node:store)
        |-
        ?~  index    node
        ?~  t.index  (get:orm graph i.index)
        =.  node     (get:orm graph i.index)
        ?~  node     ~
        ?:  ?=(%empty -.children.u.node)
          ~
        $(graph p.children.u.node, index t.index)
      ::
      ++  safe-sub
        |=  [a=@ b=@]
        ^-  @
        ?:((gte b a) 0 (sub a b))
      --
    ::
        [%depth-first @ @ ~]
      =/  count=(unit atom)  (rush i.t.t.t.t.path dem:ag)
      =/  start=(unit atom)  (rush i.t.t.t.t.t.path dem:ag)
      ?:  ?=(~ count)
        [~ ~]
      :-  ~  :-  ~  :-  %graph-update-2
      !>  ^-  update:store
      :^  now.bowl  %add-nodes  [ship term]
      =*  a  u.count
      =/  b=(list (pair atom node:store))
        (tab:orm graph start u.count)
      =|  c=index:store
      =|  d=(map index:store node:store)
      =|  e=@ud
      =-  d
      |-  ^-  [e=@ud d=(map index:store node:store)]
      ?:  ?|(?=(~ b) =(e a))
        [e d]
      =*  atom  p.i.b
      =*  node  q.i.b
      =.  c     (snoc c atom)
      ?-    -.children.node
          %empty
        $(b t.b, e +(e), d (~(put by d) c node), c (snip c))
      ::
          %graph
        =/  f  $(b (tab:orm p.children.node ~ (sub a e)))
        ?:  =(e.f a)  f
        %_  $
          b  t.b
          e  +(e.f)
          d  (~(put by d.f) c node(children [%empty ~]))
          c  (snip c)
        ==
      ==
    ==
  ==
::
++  on-arvo   on-arvo:def
++  on-agent  on-agent:def
++  on-leave  on-leave:def
++  on-fail   on-fail:def
--