feat: enhance message sending to include file attachments in Discord API

nanobot/channels/discord.py

@@ -75,7 +75,7 @@ class DiscordChannel(BaseChannel):
             self._http = None
 
     async def send(self, msg: OutboundMessage) -> None:
-        """Send a message through Discord REST API."""
+        """Send a message through Discord REST API, including file attachments."""
         if not self._http:
             logger.warning("Discord HTTP client not initialized")
             return
@@ -84,6 +84,11 @@ class DiscordChannel(BaseChannel):
         headers = {"Authorization": f"Bot {self.config.token}"}
 
         try:
+            # Send file attachments first
+            for media_path in msg.media or []:
+                await self._send_file(url, headers, media_path, reply_to=msg.reply_to)
+
+            # Send text content
             chunks = split_message(msg.content or "", MAX_MESSAGE_LEN)
             if not chunks:
                 return
@@ -91,8 +96,8 @@ class DiscordChannel(BaseChannel):
             for i, chunk in enumerate(chunks):
                 payload: dict[str, Any] = {"content": chunk}
 
-                # Only set reply reference on the first chunk
+                # Only set reply reference on the first chunk (if no media was sent)
-                if i == 0 and msg.reply_to:
+                if i == 0 and msg.reply_to and not msg.media:
                     payload["message_reference"] = {"message_id": msg.reply_to}
                     payload["allowed_mentions"] = {"replied_user": False}
 
@@ -123,6 +128,54 @@ class DiscordChannel(BaseChannel):
                     await asyncio.sleep(1)
         return False
 
+    async def _send_file(
+        self,
+        url: str,
+        headers: dict[str, str],
+        file_path: str,
+        reply_to: str | None = None,
+    ) -> bool:
+        """Send a file attachment via Discord REST API using multipart/form-data."""
+        path = Path(file_path)
+        if not path.is_file():
+            logger.warning("Discord file not found, skipping: {}", file_path)
+            return False
+
+        if path.stat().st_size > MAX_ATTACHMENT_BYTES:
+            logger.warning("Discord file too large (>20MB), skipping: {}", path.name)
+            return False
+
+        payload_json: dict[str, Any] = {}
+        if reply_to:
+            payload_json["message_reference"] = {"message_id": reply_to}
+            payload_json["allowed_mentions"] = {"replied_user": False}
+
+        for attempt in range(3):
+            try:
+                with open(path, "rb") as f:
+                    files = {"files[0]": (path.name, f, "application/octet-stream")}
+                    data: dict[str, Any] = {}
+                    if payload_json:
+                        data["payload_json"] = json.dumps(payload_json)
+                    response = await self._http.post(
+                        url, headers=headers, files=files, data=data
+                    )
+                if response.status_code == 429:
+                    resp_data = response.json()
+                    retry_after = float(resp_data.get("retry_after", 1.0))
+                    logger.warning("Discord rate limited, retrying in {}s", retry_after)
+                    await asyncio.sleep(retry_after)
+                    continue
+                response.raise_for_status()
+                logger.info("Discord file sent: {}", path.name)
+                return True
+            except Exception as e:
+                if attempt == 2:
+                    logger.error("Error sending Discord file {}: {}", path.name, e)
+                else:
+                    await asyncio.sleep(1)
+        return False
+
     async def _gateway_loop(self) -> None:
         """Main gateway loop: identify, heartbeat, dispatch events."""
         if not self._ws: