feat(weixin): add fallback logic for referenced media download

nanobot/channels/weixin.py

@@ -691,6 +691,52 @@ class WeixinChannel(BaseChannel):
                 else:
                     content_parts.append("[video]")
 
+        # Fallback: when no top-level media was downloaded, try quoted/referenced media.
+        # This aligns with the reference plugin behavior that checks ref_msg.message_item
+        # when main item_list has no downloadable media.
+        if not media_paths:
+            ref_media_item: dict[str, Any] | None = None
+            for item in item_list:
+                if item.get("type", 0) != ITEM_TEXT:
+                    continue
+                ref = item.get("ref_msg") or {}
+                candidate = ref.get("message_item") or {}
+                if candidate.get("type", 0) in (ITEM_IMAGE, ITEM_VOICE, ITEM_FILE, ITEM_VIDEO):
+                    ref_media_item = candidate
+                    break
+
+            if ref_media_item:
+                ref_type = ref_media_item.get("type", 0)
+                if ref_type == ITEM_IMAGE:
+                    image_item = ref_media_item.get("image_item") or {}
+                    file_path = await self._download_media_item(image_item, "image")
+                    if file_path:
+                        content_parts.append(f"[image]\n[Image: source: {file_path}]")
+                        media_paths.append(file_path)
+                elif ref_type == ITEM_VOICE:
+                    voice_item = ref_media_item.get("voice_item") or {}
+                    file_path = await self._download_media_item(voice_item, "voice")
+                    if file_path:
+                        transcription = await self.transcribe_audio(file_path)
+                        if transcription:
+                            content_parts.append(f"[voice] {transcription}")
+                        else:
+                            content_parts.append(f"[voice]\n[Audio: source: {file_path}]")
+                        media_paths.append(file_path)
+                elif ref_type == ITEM_FILE:
+                    file_item = ref_media_item.get("file_item") or {}
+                    file_name = file_item.get("file_name", "unknown")
+                    file_path = await self._download_media_item(file_item, "file", file_name)
+                    if file_path:
+                        content_parts.append(f"[file: {file_name}]\n[File: source: {file_path}]")
+                        media_paths.append(file_path)
+                elif ref_type == ITEM_VIDEO:
+                    video_item = ref_media_item.get("video_item") or {}
+                    file_path = await self._download_media_item(video_item, "video")
+                    if file_path:
+                        content_parts.append(f"[video]\n[Video: source: {file_path}]")
+                        media_paths.append(file_path)
+
         content = "\n".join(content_parts)
         if not content:
             return

tests/channels/test_weixin_channel.py

@@ -176,6 +176,80 @@ async def test_process_message_extracts_media_and_preserves_paths() -> None:
     assert inbound.media == ["/tmp/test.jpg"]
 
 
+@pytest.mark.asyncio
+async def test_process_message_falls_back_to_referenced_media_when_no_top_level_media() -> None:
+    channel, bus = _make_channel()
+    channel._download_media_item = AsyncMock(return_value="/tmp/ref.jpg")
+
+    await channel._process_message(
+        {
+            "message_type": 1,
+            "message_id": "m3-ref-fallback",
+            "from_user_id": "wx-user",
+            "context_token": "ctx-3-ref-fallback",
+            "item_list": [
+                {
+                    "type": ITEM_TEXT,
+                    "text_item": {"text": "reply to image"},
+                    "ref_msg": {
+                        "message_item": {
+                            "type": ITEM_IMAGE,
+                            "image_item": {"media": {"encrypt_query_param": "ref-enc"}},
+                        },
+                    },
+                },
+            ],
+        }
+    )
+
+    inbound = await asyncio.wait_for(bus.consume_inbound(), timeout=1.0)
+
+    channel._download_media_item.assert_awaited_once_with(
+        {"media": {"encrypt_query_param": "ref-enc"}},
+        "image",
+    )
+    assert inbound.media == ["/tmp/ref.jpg"]
+    assert "reply to image" in inbound.content
+    assert "[image]" in inbound.content
+
+
+@pytest.mark.asyncio
+async def test_process_message_does_not_use_referenced_fallback_when_top_level_media_exists() -> None:
+    channel, bus = _make_channel()
+    channel._download_media_item = AsyncMock(side_effect=["/tmp/top.jpg", "/tmp/ref.jpg"])
+
+    await channel._process_message(
+        {
+            "message_type": 1,
+            "message_id": "m3-ref-no-fallback",
+            "from_user_id": "wx-user",
+            "context_token": "ctx-3-ref-no-fallback",
+            "item_list": [
+                {"type": ITEM_IMAGE, "image_item": {"media": {"encrypt_query_param": "top-enc"}}},
+                {
+                    "type": ITEM_TEXT,
+                    "text_item": {"text": "has top-level media"},
+                    "ref_msg": {
+                        "message_item": {
+                            "type": ITEM_IMAGE,
+                            "image_item": {"media": {"encrypt_query_param": "ref-enc"}},
+                        },
+                    },
+                },
+            ],
+        }
+    )
+
+    inbound = await asyncio.wait_for(bus.consume_inbound(), timeout=1.0)
+
+    channel._download_media_item.assert_awaited_once_with(
+        {"media": {"encrypt_query_param": "top-enc"}},
+        "image",
+    )
+    assert inbound.media == ["/tmp/top.jpg"]
+    assert "/tmp/ref.jpg" not in inbound.content
+
+
 @pytest.mark.asyncio
 async def test_send_without_context_token_does_not_send_text() -> None:
     channel, _bus = _make_channel()