Protocol.targets: suppress mentions of in-reply-to authors

fixes #686

protocol.py

@@ -956,10 +956,14 @@ class Protocol:
 
         orig_obj = None
         targets = {}  # maps Target to Object or None
-        in_reply_to = as1.get_object(obj.as1).get('inReplyTo')
-        is_self_reply = False
         owner = as1.get_owner(obj.as1)
 
+        in_reply_to_owner = None
+        if in_reply_to := as1.get_object(obj.as1).get('inReplyTo'):
+            if in_reply_to_obj := Protocol.for_id(in_reply_to).load(in_reply_to):
+                in_reply_to_owner = as1.get_owner(in_reply_to_obj.as1)
+        is_self_reply = False
+
         for id in sorted(target_uris):
             protocol = Protocol.for_id(id)
             if not protocol:
@@ -971,6 +975,9 @@ class Protocol:
             elif protocol.is_blocklisted(id):
                 logger.info(f'{id} is blocklisted')
                 continue
+            elif id == in_reply_to_owner:
+                logger.info(f'Skipping mention of in-reply-to author')
+                continue
 
             orig_obj = protocol.load(id)
             if not orig_obj or not orig_obj.as1:

tests/test_protocol.py

@@ -864,6 +864,41 @@ class ProtocolReceiveTest(TestCase):
             (obj.key.id(), 'other:eve:target'),
         ], OtherFake.sent)
 
+    def test_reply_skips_mention_of_original_post_author(self):
+        bob = self.store_object(id='fake:bob', our_as1={'foo': 1})
+        eve = self.store_object(id='fake:eve', our_as1={'foo': 2})
+
+        reply_as1 = {
+            'id': 'other:reply',
+            'objectType': 'note',
+            'inReplyTo': 'fake:post',
+            'author': 'other:alice',
+            'content': 'foo',
+            'tags': [{
+                'objectType': 'mention',
+                'url': 'fake:eve',
+            }, {
+                'objectType': 'mention',
+                'url': 'fake:bob',
+            }],
+        }
+        Fake.fetchable = {
+            'fake:post': {
+                'objectType': 'note',
+                'id': 'fake:post',
+                'author': 'fake:bob',
+            },
+        }
+        self.assertEqual(('OK', 202), Fake.receive_as1(reply_as1))
+
+        obj = Object.get_by_id('other:reply#bridgy-fed-create')
+        self.assertEqual([Fake(id='fake:bob').key], obj.notify)
+        self.assertEqual([
+            # bob shouldn't be here, we should suppress the mention
+            (obj.key.id(), 'fake:eve:target'),
+            (obj.key.id(), 'fake:post:target'),
+        ], Fake.sent)
+
     def test_update_reply(self):
         self.make_followers()