A %coup failure from gall should return a 500 to the client.

sys/vane/rver.hoon

@@ -1357,20 +1357,29 @@
     --
   ::  +handle-ford-response: translates a ford response for the outside world
   ::
-  ::    TODO: Get the authentication state and source url here.
-  ::
   ++  handle-ford-response
     |=  made-result=made-result:ford
     ^-  [(list move) server-state]
     ::
+    =+  connection=(~(got by connections.state) duct)
+    ::
     ?:  ?=(%incomplete -.made-result)
       %^  return-static-data-on-duct  500  'text/html'
-      ::  TODO: Thread original URL and authentication state here.
+      ::
-      (internal-server-error %.y 'http://' tang.made-result)
+      %-  internal-server-error  :*
+          authenticated.inbound-request.connection
+          url.request.inbound-request.connection
+          tang.made-result
+      ==
     ::
     ?:  ?=(%error -.build-result.made-result)
       %^  return-static-data-on-duct  500  'text/html'
-      (internal-server-error %.y 'http://' message.build-result.made-result)
+      ::
+      %-  internal-server-error  :*
+          authenticated.inbound-request.connection
+          url.request.inbound-request.connection
+          message.build-result.made-result
+      ==
     ::
     =/  =cage  (result-to-cage:ford build-result.made-result)
     ::
@@ -1387,6 +1396,21 @@
         `(unit octs)`[~ q.result]
         complete=%.y
     ==
+  ::  +handle-gall-error: a call to +poke-http-response resulted in a %coup
+  ::
+  ++  handle-gall-error
+    |=  =tang
+    ^-  [(list move) server-state]
+    ::
+    =+  connection=(~(got by connections.state) duct)
+    ::
+    %^  return-static-data-on-duct  500  'text/html'
+    ::
+    %-  internal-server-error  :*
+        authenticated.inbound-request.connection
+        url.request.inbound-request.connection
+        tang
+    ==
   ::  +handle-response: check a response for correctness and send to earth
   ::
   ::    All outbound responses including %http-server generated responses need to go
@@ -1710,11 +1734,23 @@
   ::
   ++  run-app
     ::
-    ?.  ?=([%g %unto %http-response *] sign)
+    ?>  ?=([%g %unto *] sign)
-      ::  entirely normal to get things other than http-response calls, but we
+    ::
-      ::  don't care.
+    ::
+    ?:  ?=([%coup *] p.sign)
+      ?~  p.p.sign
+        ::  received a positive acknowledgment: take no action
+        ::
+        [~ http-server-gate]
+      ::  we have an error; propagate it to the client
       ::
-      [~ http-server-gate]
+      =/  event-args  [[our eny duct now scry-gate] server-state.ax]
+      =/  handle-gall-error
+        handle-gall-error:(per-server-event event-args)
+      =^  moves  server-state.ax  (handle-gall-error u.p.p.sign)
+      [moves http-server-gate]
+    ::
+    ?>  ?=([%g %unto %http-response *] sign)
     ::
     =/  event-args  [[our eny duct now scry-gate] server-state.ax]
     =/  handle-response  handle-response:(per-server-event event-args)

tests/sys/vane/rver.hoon

@@ -285,6 +285,96 @@
     results4
   ==
 ::
+++  test-app-error
+  ::
+  =^  results1  http-server-gate
+    %-  http-server-call  :*
+      http-server-gate
+      now=~1111.1.1
+      scry=scry-provides-code
+      call-args=[duct=~[/init] ~ [%init ~nul]]
+      expected-moves=~
+    ==
+  ::  app1 binds successfully
+  ::
+  =^  results2  http-server-gate
+    %-  http-server-call  :*
+      http-server-gate
+      now=~1111.1.2
+      scry=scry-provides-code
+      call-args=[duct=~[/app1] ~ [%connect [~ /] %app1]]
+      expected-moves=[duct=~[/app1] %give %bound %.y [~ /]]~
+    ==
+  ::  outside requests a path that app1 has bound to
+  ::
+  =^  results3  http-server-gate
+    %-  http-server-call-with-comparator  :*
+      http-server-gate
+      now=~1111.1.3
+      scry=scry-provides-code
+      ^=  call-args
+        :*  duct=~[/http-blah]  ~
+            %request
+            %.n
+            [%ipv4 .192.168.1.1]
+            [%'GET' '/' ~ ~]
+        ==
+      ^=  comparator
+        |=  moves=(list move:http-server-gate)
+        ^-  tang
+        ::
+        ?.  ?=([* ~] moves)
+          [%leaf "wrong number of moves: {<(lent moves)>}"]~
+        ::
+        ::
+        =/  move=move:http-server-gate                              i.moves
+        =/  =duct                                             duct.move
+        =/  card=(wind note:http-server-gate gift:able:http-server-gate)  card.move
+        ::
+        %+  weld
+          (expect-eq !>(~[/http-blah]) !>(duct))
+        ::
+        %+  expect-gall-deal
+          :+  /run-app/app1  [~nul ~nul]
+              ^-  cush:gall
+              :*  %app1  %poke  %handle-http-request
+                  !>([%.n %.n [%ipv4 .192.168.1.1] [%'GET' '/' ~ ~]])
+              ==
+          card
+    ==
+  ::  the poke fails. we should relay this to the client
+  ::
+  =^  results4  http-server-gate
+    %-  http-server-take  :*
+      http-server-gate
+      now=~1111.1.4
+      scry=scry-provides-code
+      ^=  take-args
+        :*  wire=/run-app/app1  duct=~[/http-blah]
+            ^-  (hypo sign:http-server-gate)
+            :-  *type
+            :*  %g  %unto  %coup  ~
+                :~  [%leaf "/~zod/...../app1:<[1 1].[1 20]>"]
+            ==  ==
+         ==
+      ^=  expected-move
+        :~  :*  duct=~[/http-blah]  %give  %response
+                %start
+                :-  500
+                :~  ['content-type' 'text/html']
+                    ['content-length' '180']
+                ==
+                [~ (internal-server-error:http-server-gate %.n '/' ~)]
+                complete=%.y
+    ==  ==  ==
+  ::
+  ;:  weld
+    results1
+    results2
+    results3
+    results4
+  ==
+::
 ++  test-multipart-app-request
   ::
   =^  results1  http-server-gate