fix(discord): preserve native document and video attachment support

Salvaged from PR #1115 onto current main by reusing the shared
Discord file-attachment helper for local video and document sends,
including file_name support for documents and regression coverage.

gateway/platforms/discord.py

@@ -669,6 +669,7 @@ class DiscordAdapter(BasePlatformAdapter):
         chat_id: str,
         file_path: str,
         caption: Optional[str] = None,
+        file_name: Optional[str] = None,
     ) -> SendResult:
         """Send a local file as a Discord attachment."""
         if not self._client:
@@ -680,7 +681,7 @@ class DiscordAdapter(BasePlatformAdapter):
         if not channel:
             return SendResult(success=False, error=f"Channel {chat_id} not found")
 
-        filename = os.path.basename(file_path)
+        filename = file_name or os.path.basename(file_path)
         with open(file_path, "rb") as fh:
             file = discord.File(fh, filename=filename)
             msg = await channel.send(content=caption if caption else None, file=file)
@@ -1142,6 +1143,41 @@ class DiscordAdapter(BasePlatformAdapter):
             )
             return await super().send_image(chat_id, image_url, caption, reply_to)
 
+    async def send_video(
+        self,
+        chat_id: str,
+        video_path: str,
+        caption: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> SendResult:
+        """Send a local video file natively as a Discord attachment."""
+        try:
+            return await self._send_file_attachment(chat_id, video_path, caption)
+        except FileNotFoundError:
+            return SendResult(success=False, error=f"Video file not found: {video_path}")
+        except Exception as e:  # pragma: no cover - defensive logging
+            logger.error("[%s] Failed to send local video, falling back to base adapter: %s", self.name, e, exc_info=True)
+            return await super().send_video(chat_id, video_path, caption, reply_to, metadata=metadata)
+
+    async def send_document(
+        self,
+        chat_id: str,
+        file_path: str,
+        caption: Optional[str] = None,
+        file_name: Optional[str] = None,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> SendResult:
+        """Send an arbitrary file natively as a Discord attachment."""
+        try:
+            return await self._send_file_attachment(chat_id, file_path, caption, file_name=file_name)
+        except FileNotFoundError:
+            return SendResult(success=False, error=f"File not found: {file_path}")
+        except Exception as e:  # pragma: no cover - defensive logging
+            logger.error("[%s] Failed to send document, falling back to base adapter: %s", self.name, e, exc_info=True)
+            return await super().send_document(chat_id, file_path, caption, file_name, reply_to, metadata=metadata)
+    
     async def send_typing(self, chat_id: str, metadata=None) -> None:
         """Send typing indicator."""
         if self._client:

tests/gateway/test_send_image_file.py

@@ -199,6 +199,57 @@ class TestDiscordSendImageFile:
         assert result.message_id == "99"
         mock_channel.send.assert_awaited_once()
 
+    def test_send_document_uploads_file_attachment(self, adapter, tmp_path):
+        """send_document should upload a native Discord attachment."""
+        pdf = tmp_path / "sample.pdf"
+        pdf.write_bytes(b"%PDF-1.4\n%\xe2\xe3\xcf\xd3\n")
+
+        mock_channel = MagicMock()
+        mock_msg = MagicMock()
+        mock_msg.id = 100
+        mock_channel.send = AsyncMock(return_value=mock_msg)
+        adapter._client.get_channel = MagicMock(return_value=mock_channel)
+
+        with patch.object(discord_mod_ref, "File", MagicMock()) as file_cls:
+            result = _run(
+                adapter.send_document(
+                    chat_id="67890",
+                    file_path=str(pdf),
+                    file_name="renamed.pdf",
+                    metadata={"thread_id": "123"},
+                )
+            )
+
+        assert result.success
+        assert result.message_id == "100"
+        assert "file" in mock_channel.send.call_args.kwargs
+        assert file_cls.call_args.kwargs["filename"] == "renamed.pdf"
+
+    def test_send_video_uploads_file_attachment(self, adapter, tmp_path):
+        """send_video should upload a native Discord attachment."""
+        video = tmp_path / "clip.mp4"
+        video.write_bytes(b"\x00\x00\x00\x18ftypmp42" + b"\x00" * 50)
+
+        mock_channel = MagicMock()
+        mock_msg = MagicMock()
+        mock_msg.id = 101
+        mock_channel.send = AsyncMock(return_value=mock_msg)
+        adapter._client.get_channel = MagicMock(return_value=mock_channel)
+
+        with patch.object(discord_mod_ref, "File", MagicMock()) as file_cls:
+            result = _run(
+                adapter.send_video(
+                    chat_id="67890",
+                    video_path=str(video),
+                    metadata={"thread_id": "123"},
+                )
+            )
+
+        assert result.success
+        assert result.message_id == "101"
+        assert "file" in mock_channel.send.call_args.kwargs
+        assert file_cls.call_args.kwargs["filename"] == "clip.mp4"
+
     def test_returns_error_when_file_missing(self, adapter):
         result = _run(
             adapter.send_image_file(chat_id="67890", image_path="/nonexistent.png")