AP: Fix incoming conversations.

lib/pleroma/web/activity_pub/transmogrifier.ex

@@ -14,6 +14,12 @@ def fix_object(object) do
     object
     |> Map.put("actor", object["attributedTo"])
     |> fix_attachments
+    |> fix_context
+  end
+
+  def fix_context(object) do
+    object
+    |> Map.put("context", object["conversation"])
   end
 
   def fix_attachments(object) do
@@ -130,7 +136,8 @@ def add_hashtags(object) do
   end
 
   def add_mention_tags(object) do
-    mentions = object["to"]
+    recipients = object["to"] ++ (object["cc"] || [])
+    mentions = recipients
     |> Enum.map(fn (ap_id) -> User.get_cached_by_ap_id(ap_id) end)
     |> Enum.filter(&(&1))
     |> Enum.map(fn(user) -> %{"type" => "Mention", "href" => user.ap_id, "name" => "@#{user.nickname}"} end)

test/web/activity_pub/transmogrifier_test.exs

@@ -33,6 +33,7 @@ test "it works for incoming notices" do
       ]
       assert object["actor"] == "http://mastodon.example.org/users/admin"
       assert object["attributedTo"] == "http://mastodon.example.org/users/admin"
+      assert object["context"] == "tag:mastodon.example.org,2018-02-12:objectId=20:objectType=Conversation"
       assert object["sensitive"] == true
     end
 
@@ -111,6 +112,7 @@ test "it turns mentions into tags" do
         "name" => "@#{other_user.nickname}",
         "type" => "Mention"
       }
+
       expected_tag = %{
         "href" => Pleroma.Web.Endpoint.url <> "/tags/2hu",
         "type" => "Hashtag",