fix: avoid masking missed Discord parent messages

Preserve startup missed-message backfill behavior while avoiding false address classifications from unrelated parent-channel messages.

plugins/platforms/discord/adapter.py

@@ -2159,7 +2159,7 @@ class DiscordAdapter(BasePlatformAdapter):
         if bot_id is None:
             return False
 
-        async def _scan_history(channel: Any) -> bool:
+        async def _scan_history(channel: Any, *, allow_unreferenced_bot_response: bool) -> bool:
             history = getattr(channel, "history", None)
             if not callable(history):
                 return False
@@ -2172,17 +2172,28 @@ class DiscordAdapter(BasePlatformAdapter):
                         continue
                     reference = getattr(candidate, "reference", None)
                     ref_id = str(getattr(reference, "message_id", "") or "")
-                    if not ref_id or ref_id == str(getattr(message, "id", "")):
+                    if ref_id == str(getattr(message, "id", "")):
+                        return True
+                    if allow_unreferenced_bot_response and not ref_id:
                         return True
             except Exception:
                 return False
             return False
 
-        if await _scan_history(getattr(message, "channel", None)):
+        message_channel = getattr(message, "channel", None)
+        # In a thread, bot responses are usually ordinary unreferenced messages
+        # after the user's post.  In a parent channel, however, an unreferenced
+        # bot post after a user message is not evidence that it answered this
+        # specific message; otherwise one successful reply can mask multiple
+        # missed parent-channel posts after a rate-limit/outage burst.
+        if await _scan_history(
+            message_channel,
+            allow_unreferenced_bot_response=bool(getattr(message_channel, "parent_id", None)),
+        ):
             return True
 
         thread = getattr(message, "thread", None)
-        if thread is not None and await _scan_history(thread):
+        if thread is not None and await _scan_history(thread, allow_unreferenced_bot_response=True):
             return True
         return False
 

tests/gateway/test_discord_missed_message_backfill.py

@@ -60,8 +60,9 @@ class FakeReaction:
 
 
 class FakeChannel:
-    def __init__(self, channel_id=123, history_messages=None):
+    def __init__(self, channel_id=123, history_messages=None, parent_id=None):
         self.id = channel_id
+        self.parent_id = parent_id
         self.name = "wiki-inbox"
         self.guild = SimpleNamespace(name="emo")
         self.topic = None
@@ -124,6 +125,36 @@ async def test_should_not_backfill_message_with_non_down_bot_response(adapter):
     assert await adapter._should_backfill_discord_message(message) is False
 
 
+@pytest.mark.asyncio
+async def test_parent_channel_unreferenced_bot_message_does_not_suppress_backfill(adapter):
+    unrelated_bot_post = SimpleNamespace(
+        id=2,
+        content="Done — captured a different item.",
+        author=SimpleNamespace(id=999, bot=True),
+        reference=None,
+        created_at=datetime.now(timezone.utc),
+    )
+    channel = FakeChannel(history_messages=[unrelated_bot_post])
+    message = make_message(message_id=1, channel=channel)
+
+    assert await adapter._should_backfill_discord_message(message) is True
+
+
+@pytest.mark.asyncio
+async def test_thread_unreferenced_bot_message_suppresses_backfill(adapter):
+    bot_post = SimpleNamespace(
+        id=2,
+        content="Done — captured it.",
+        author=SimpleNamespace(id=999, bot=True),
+        reference=None,
+        created_at=datetime.now(timezone.utc),
+    )
+    thread = FakeChannel(channel_id=456, parent_id=123, history_messages=[bot_post])
+    message = make_message(message_id=1, channel=thread)
+
+    assert await adapter._should_backfill_discord_message(message) is False
+
+
 @pytest.mark.asyncio
 async def test_backfills_when_only_down_notice_exists(adapter):
     down_notice = SimpleNamespace(