fix(discord): drop invalid reply references

gateway/platforms/discord.py

@@ -873,7 +873,10 @@ class DiscordAdapter(BasePlatformAdapter):
             if reply_to and self._reply_to_mode != "off":
                 try:
                     ref_msg = await channel.fetch_message(int(reply_to))
-                    reference = ref_msg
+                    if hasattr(ref_msg, "to_reference"):
+                        reference = ref_msg.to_reference(fail_if_not_exists=False)
+                    else:
+                        reference = ref_msg
                 except Exception as e:
                     logger.debug("Could not fetch reply-to message: %s", e)
 
@@ -891,14 +894,20 @@ class DiscordAdapter(BasePlatformAdapter):
                     err_text = str(e)
                     if (
                         chunk_reference is not None
-                        and "error code: 50035" in err_text
-                        and "Cannot reply to a system message" in err_text
+                        and (
+                            (
+                                "error code: 50035" in err_text
+                                and "Cannot reply to a system message" in err_text
+                            )
+                            or "error code: 10008" in err_text
+                        )
                     ):
                         logger.warning(
-                            "[%s] Reply target %s is a Discord system message; retrying send without reply reference",
+                            "[%s] Reply target %s rejected the reply reference; retrying send without reply reference",
                             self.name,
                             reply_to,
                         )
+                        reference = None
                         msg = await channel.send(
                             content=chunk,
                             reference=None,

tests/gateway/test_discord_send.py

@@ -48,7 +48,8 @@ from gateway.platforms.discord import DiscordAdapter  # noqa: E402
 async def test_send_retries_without_reference_when_reply_target_is_system_message():
     adapter = DiscordAdapter(PlatformConfig(enabled=True, token="***"))
 
-    ref_msg = SimpleNamespace(id=99)
+    reference_obj = object()
+    ref_msg = SimpleNamespace(id=99, to_reference=MagicMock(return_value=reference_obj))
     sent_msg = SimpleNamespace(id=1234)
     send_calls = []
 
@@ -76,5 +77,45 @@ async def test_send_retries_without_reference_when_reply_target_is_system_messag
     assert result.message_id == "1234"
     assert channel.fetch_message.await_count == 1
     assert channel.send.await_count == 2
-    assert send_calls[0]["reference"] is ref_msg
+    ref_msg.to_reference.assert_called_once_with(fail_if_not_exists=False)
+    assert send_calls[0]["reference"] is reference_obj
     assert send_calls[1]["reference"] is None
+
+
+@pytest.mark.asyncio
+async def test_send_retries_without_reference_when_reply_target_is_deleted():
+    adapter = DiscordAdapter(PlatformConfig(enabled=True, token="***"))
+
+    reference_obj = object()
+    ref_msg = SimpleNamespace(id=99, to_reference=MagicMock(return_value=reference_obj))
+    sent_msgs = [SimpleNamespace(id=1001), SimpleNamespace(id=1002)]
+    send_calls = []
+
+    async def fake_send(*, content, reference=None):
+        send_calls.append({"content": content, "reference": reference})
+        if len(send_calls) == 1:
+            raise RuntimeError(
+                "400 Bad Request (error code: 10008): Unknown Message"
+            )
+        return sent_msgs[len(send_calls) - 2]
+
+    channel = SimpleNamespace(
+        fetch_message=AsyncMock(return_value=ref_msg),
+        send=AsyncMock(side_effect=fake_send),
+    )
+    adapter._client = SimpleNamespace(
+        get_channel=lambda _chat_id: channel,
+        fetch_channel=AsyncMock(),
+    )
+
+    long_text = "A" * (adapter.MAX_MESSAGE_LENGTH + 50)
+    result = await adapter.send("555", long_text, reply_to="99")
+
+    assert result.success is True
+    assert result.message_id == "1001"
+    assert channel.fetch_message.await_count == 1
+    assert channel.send.await_count == 3
+    ref_msg.to_reference.assert_called_once_with(fail_if_not_exists=False)
+    assert send_calls[0]["reference"] is reference_obj
+    assert send_calls[1]["reference"] is None
+    assert send_calls[2]["reference"] is None