From 6d406d93c902e209f56f9f0ec0872fcb8abb5aa6 Mon Sep 17 00:00:00 2001
From: chengyongru <chengyongru.ai@gmail.com>
Date: Mon, 13 Jul 2026 10:20:44 +0800
Subject: [PATCH] fix(discord): route unauthorized DMs to pairing

---
 nanobot/channels/discord.py            |  4 +++-
 tests/channels/test_discord_channel.py | 20 ++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/nanobot/channels/discord.py b/nanobot/channels/discord.py
index 9e0f9829..94781913 100644
--- a/nanobot/channels/discord.py
+++ b/nanobot/channels/discord.py
@@ -664,7 +664,9 @@ class DiscordChannel(BaseChannel):
         content: str,
     ) -> bool:
         """Check if inbound Discord message should be processed."""
-        if not self.is_allowed(sender_id):
+        # Reject unauthorized guild messages before any side effects, but let DMs
+        # reach BaseChannel._handle_message so it can issue a pairing code.
+        if message.guild is not None and not self.is_allowed(sender_id):
             return False
         # Channel-based filtering: only respond in allowed channels
         allow_channels = self.config.allow_channels
diff --git a/tests/channels/test_discord_channel.py b/tests/channels/test_discord_channel.py
index 9ce91a9f..717e3108 100644
--- a/tests/channels/test_discord_channel.py
+++ b/tests/channels/test_discord_channel.py
@@ -362,6 +362,26 @@ async def test_on_message_accepts_allowlisted_dm() -> None:
     assert handled[0]["metadata"] == {"message_id": "789", "guild_id": None, "reply_to": None}
 
 
+@pytest.mark.asyncio
+async def test_on_message_unauthorized_dm_sends_pairing_code(monkeypatch) -> None:
+    channel = DiscordChannel(DiscordConfig(enabled=True, allow_from=[]), MessageBus())
+    client = _FakeDiscordClient(channel, intents=None)
+    message = _make_message(author_id=123, channel_id=456)
+    client.channels[456] = message.channel
+    channel._client = client
+    channel._running = True
+    monkeypatch.setattr("nanobot.channels.base.is_approved", lambda _ch, _sid: False)
+    monkeypatch.setattr(
+        "nanobot.channels.base.generate_code", lambda _ch, _sid: "ABCD-EFGH"
+    )
+
+    await channel._on_message(message)
+
+    assert len(message.channel.sent_payloads) == 1
+    assert "ABCD-EFGH" in message.channel.sent_payloads[0]["content"]
+    assert channel._typing_tasks == {}
+
+
 @pytest.mark.asyncio
 async def test_on_message_accepts_when_channel_in_allow_channels() -> None:
     # When allow_channels is set, messages from listed channels should be forwarded.