verb: allow subscribing to events

This excludes, necessarily, events that don't let us emit moves.
(+on-save, +on-peek)

pkg/arvo/lib/verb.hoon

@@ -1,5 +1,7 @@
 ::  Print what your agent is doing.
 ::
+/-  verb
+::
 |=  [loud=? =agent:gall]
 =|  bowl-print=_|
 ^-  agent:gall
@@ -12,7 +14,7 @@
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-init")
   =^  cards  agent  on-init:ag
-  [cards this]
+  [[(emit-event %on-init ~) cards] this]
 ::
 ++  on-save
   ^-  vase
@@ -24,7 +26,7 @@
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-load")
   =^  cards  agent  (on-load:ag old-state)
-  [cards this]
+  [[(emit-event %on-load ~) cards] this]
 ::
 ++  on-poke
   |=  [=mark =vase]
@@ -36,21 +38,26 @@
       %bowl  `this(bowl-print !bowl-print)
     ==
   =^  cards  agent  (on-poke:ag mark vase)
-  [cards this]
+  [[(emit-event %on-poke mark) cards] this]
 ::
 ++  on-watch
   |=  =path
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-watch on path {<path>}")
-  =^  cards  agent  (on-watch:ag path)
-  [cards this]
+  =^  cards  agent
+    ?:  ?=([%verb %events ~] path)
+      [~ agent]
+    (on-watch:ag path)
+  [[(emit-event %on-watch path) cards] this]
 ::
 ++  on-leave
   |=  =path
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-leave on path {<path>}")
+  ?:  ?=([%verb %event ~] path)
+    [~ this]
   =^  cards  agent  (on-leave:ag path)
-  [cards this]
+  [[(emit-event %on-leave path) cards] this]
 ::
 ++  on-peek
   |=  =path
@@ -63,21 +70,21 @@
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-agent on wire {<wire>}, {<-.sign>}")
   =^  cards  agent  (on-agent:ag wire sign)
-  [cards this]
+  [[(emit-event %on-agent wire -.sign) cards] this]
 ::
 ++  on-arvo
   |=  [=wire =sign-arvo]
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-arvo on wire {<wire>}, {<[- +<]:sign-arvo>}")
   =^  cards  agent  (on-arvo:ag wire sign-arvo)
-  [cards this]
+  [[(emit-event %on-arvo wire [- +<]:sign-arvo) cards] this]
 ::
 ++  on-fail
   |=  [=term =tang]
   ^-  (quip card:agent:gall agent:gall)
   %-  (print bowl "{<dap.bowl>}: on-fail with term {<term>}")
   =^  cards  agent  (on-fail:ag term tang)
-  [cards this]
+  [[(emit-event %on-fail term) cards] this]
 --
 ::
 ++  print
@@ -89,4 +96,9 @@
   ?.  loud  same
   %-  (slog leaf+tape ~)
   same
+::
+++  emit-event
+  |=  =event:verb
+  ^-  card:agent:gall
+  [%give %fact ~[/verb/events] %verb-event !>(event)]
 --

pkg/arvo/mar/verb/event.hoon

@@ -0,0 +1,26 @@
+/-  verb
+=,  dejs:format
+|_  =event:verb
+++  grab
+  |%
+  ++  noun  event:verb
+  --
+::
+++  grow
+  |%
+  ++  noun  event
+  ++  json
+    =,  enjs:format
+    %+  frond  -.event
+    ?-  -.event
+      %on-init   ~
+      %on-load   ~
+      %on-poke   s+mark.event
+      %on-watch  (path path.event)
+      %on-leave  (path path.event)
+      %on-agent  (pairs 'wire'^(path wire.event) 'sign'^s+sign.event ~)
+      %on-arvo   (pairs 'wire'^(path wire.event) 'vane'^s+vane.event 'sign'^s+sign.event ~)
+      %on-fail   s+term.event
+    ==
+  --
+--

pkg/arvo/sur/verb.hoon

@@ -0,0 +1,12 @@
+|%
++$  event
+  $%  [%on-init ~]
+      [%on-load ~]
+      [%on-poke =mark]
+      [%on-watch =path]
+      [%on-leave =path]
+      [%on-agent =wire sign=term]
+      [%on-arvo =wire vane=term sign=term]
+      [%on-fail =term]
+  ==
+--