diff --git a/tests/channels/test_qq_media.py b/tests/channels/test_qq_media.py
new file mode 100644
index 000000000..80a5ad20e
--- /dev/null
+++ b/tests/channels/test_qq_media.py
@@ -0,0 +1,304 @@
+"""Tests for QQ channel media support: helpers, send, inbound, and upload."""
+
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+try:
+    from nanobot.channels import qq
+
+    QQ_AVAILABLE = getattr(qq, "QQ_AVAILABLE", False)
+except ImportError:
+    QQ_AVAILABLE = False
+
+if not QQ_AVAILABLE:
+    pytest.skip("QQ dependencies not installed (qq-botpy)", allow_module_level=True)
+
+from nanobot.bus.events import OutboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.channels.qq import (
+    QQ_FILE_TYPE_FILE,
+    QQ_FILE_TYPE_IMAGE,
+    QQChannel,
+    QQConfig,
+    _guess_send_file_type,
+    _is_image_name,
+    _sanitize_filename,
+)
+
+
+class _FakeApi:
+    def __init__(self) -> None:
+        self.c2c_calls: list[dict] = []
+        self.group_calls: list[dict] = []
+
+    async def post_c2c_message(self, **kwargs) -> None:
+        self.c2c_calls.append(kwargs)
+
+    async def post_group_message(self, **kwargs) -> None:
+        self.group_calls.append(kwargs)
+
+
+class _FakeHttp:
+    """Fake _http for _post_base64file tests."""
+
+    def __init__(self, return_value: dict | None = None) -> None:
+        self.return_value = return_value or {}
+        self.calls: list[tuple] = []
+
+    async def request(self, route, **kwargs):
+        self.calls.append((route, kwargs))
+        return self.return_value
+
+
+class _FakeClient:
+    def __init__(self, http_return: dict | None = None) -> None:
+        self.api = _FakeApi()
+        self.api._http = _FakeHttp(http_return)
+
+
+# ── Helper function tests (pure, no async) ──────────────────────────
+
+
+def test_sanitize_filename_strips_path_traversal() -> None:
+    assert _sanitize_filename("../../etc/passwd") == "passwd"
+
+
+def test_sanitize_filename_keeps_chinese_chars() -> None:
+    assert _sanitize_filename("文件（1）.jpg") == "文件（1）.jpg"
+
+
+def test_sanitize_filename_strips_unsafe_chars() -> None:
+    result = _sanitize_filename('file<>:"|?*.txt')
+    # All unsafe chars replaced with "_", but * is replaced too
+    assert result.startswith("file")
+    assert result.endswith(".txt")
+    assert "<" not in result
+    assert ">" not in result
+    assert '"' not in result
+    assert "|" not in result
+    assert "?" not in result
+
+
+def test_sanitize_filename_empty_input() -> None:
+    assert _sanitize_filename("") == ""
+
+
+def test_is_image_name_with_known_extensions() -> None:
+    for ext in (".png", ".jpg", ".jpeg", ".gif", ".bmp", ".webp", ".tif", ".tiff", ".ico", ".svg"):
+        assert _is_image_name(f"photo{ext}") is True
+
+
+def test_is_image_name_with_unknown_extension() -> None:
+    for ext in (".pdf", ".txt", ".mp3", ".mp4"):
+        assert _is_image_name(f"doc{ext}") is False
+
+
+def test_guess_send_file_type_image() -> None:
+    assert _guess_send_file_type("photo.png") == QQ_FILE_TYPE_IMAGE
+    assert _guess_send_file_type("pic.jpg") == QQ_FILE_TYPE_IMAGE
+
+
+def test_guess_send_file_type_file() -> None:
+    assert _guess_send_file_type("doc.pdf") == QQ_FILE_TYPE_FILE
+
+
+def test_guess_send_file_type_by_mime() -> None:
+    # A filename with no known extension but whose mime type is image/*
+    assert _guess_send_file_type("photo.xyz_image_test") == QQ_FILE_TYPE_FILE
+
+
+# ── send() exception handling ───────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_send_exception_caught_not_raised() -> None:
+    """Exceptions inside send() must not propagate."""
+    channel = QQChannel(QQConfig(app_id="app", secret="secret", allow_from=["*"]), MessageBus())
+    channel._client = _FakeClient()
+
+    with patch.object(channel, "_send_text_only", new_callable=AsyncMock, side_effect=RuntimeError("boom")):
+        await channel.send(
+            OutboundMessage(channel="qq", chat_id="user1", content="hello")
+        )
+    # No exception raised — test passes if we get here.
+
+
+@pytest.mark.asyncio
+async def test_send_media_then_text() -> None:
+    """Media is sent before text when both are present."""
+    import tempfile
+
+    channel = QQChannel(QQConfig(app_id="app", secret="secret", allow_from=["*"]), MessageBus())
+    channel._client = _FakeClient()
+
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        tmp = f.name
+
+    try:
+        with patch.object(channel, "_post_base64file", new_callable=AsyncMock, return_value={"file_info": "1"}) as mock_upload:
+            await channel.send(
+                OutboundMessage(
+                    channel="qq",
+                    chat_id="user1",
+                    content="text after image",
+                    media=[tmp],
+                    metadata={"message_id": "m1"},
+                )
+            )
+            assert mock_upload.called
+
+        # Text should have been sent via c2c (default chat type)
+        text_calls = [c for c in channel._client.api.c2c_calls if c.get("msg_type") == 0]
+        assert len(text_calls) >= 1
+        assert text_calls[-1]["content"] == "text after image"
+    finally:
+        import os
+        os.unlink(tmp)
+
+
+@pytest.mark.asyncio
+async def test_send_media_failure_falls_back_to_text() -> None:
+    """When _send_media returns False, a failure notice is appended."""
+    channel = QQChannel(QQConfig(app_id="app", secret="secret", allow_from=["*"]), MessageBus())
+    channel._client = _FakeClient()
+
+    with patch.object(channel, "_send_media", new_callable=AsyncMock, return_value=False):
+        await channel.send(
+            OutboundMessage(
+                channel="qq",
+                chat_id="user1",
+                content="hello",
+                media=["https://example.com/bad.png"],
+                metadata={"message_id": "m1"},
+            )
+        )
+
+    # Should have the failure text among the c2c calls
+    failure_calls = [c for c in channel._client.api.c2c_calls if "Attachment send failed" in c.get("content", "")]
+    assert len(failure_calls) == 1
+    assert "bad.png" in failure_calls[0]["content"]
+
+
+# ── _on_message() exception handling ────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_on_message_exception_caught_not_raised() -> None:
+    """Missing required attributes should not crash _on_message."""
+    channel = QQChannel(QQConfig(app_id="app", secret="secret", allow_from=["*"]), MessageBus())
+    channel._client = _FakeClient()
+
+    # Construct a message-like object that lacks 'author' — triggers AttributeError
+    bad_data = SimpleNamespace(id="x1", content="hi")
+    # Should not raise
+    await channel._on_message(bad_data, is_group=False)
+
+
+@pytest.mark.asyncio
+async def test_on_message_with_attachments() -> None:
+    """Messages with attachments produce media_paths and formatted content."""
+    import tempfile
+
+    channel = QQChannel(QQConfig(app_id="app", secret="secret", allow_from=["*"]), MessageBus())
+    channel._client = _FakeClient()
+
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        saved_path = f.name
+
+    att = SimpleNamespace(url="", filename="screenshot.png", content_type="image/png")
+
+    # Patch _download_to_media_dir_chunked to return the temp file path
+    async def fake_download(url, filename_hint=""):
+        return saved_path
+
+    try:
+        with patch.object(channel, "_download_to_media_dir_chunked", side_effect=fake_download):
+            data = SimpleNamespace(
+                id="att1",
+                content="look at this",
+                author=SimpleNamespace(user_openid="u1"),
+                attachments=[att],
+            )
+            await channel._on_message(data, is_group=False)
+
+        msg = await channel.bus.consume_inbound()
+        assert "look at this" in msg.content
+        assert "screenshot.png" in msg.content
+        assert "Received files:" in msg.content
+        assert len(msg.media) == 1
+        assert msg.media[0] == saved_path
+    finally:
+        import os
+        os.unlink(saved_path)
+
+
+# ── _post_base64file() ─────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_post_base64file_omits_file_name_for_images() -> None:
+    """file_type=1 (image) → payload must not contain file_name."""
+    channel = QQChannel(QQConfig(app_id="app", secret="secret"), MessageBus())
+    channel._client = _FakeClient(http_return={"file_info": "img_abc"})
+
+    await channel._post_base64file(
+        chat_id="user1",
+        is_group=False,
+        file_type=QQ_FILE_TYPE_IMAGE,
+        file_data="ZmFrZQ==",
+        file_name="photo.png",
+    )
+
+    http = channel._client.api._http
+    assert len(http.calls) == 1
+    payload = http.calls[0][1]["json"]
+    assert "file_name" not in payload
+    assert payload["file_type"] == QQ_FILE_TYPE_IMAGE
+
+
+@pytest.mark.asyncio
+async def test_post_base64file_includes_file_name_for_files() -> None:
+    """file_type=4 (file) → payload must contain file_name."""
+    channel = QQChannel(QQConfig(app_id="app", secret="secret"), MessageBus())
+    channel._client = _FakeClient(http_return={"file_info": "file_abc"})
+
+    await channel._post_base64file(
+        chat_id="user1",
+        is_group=False,
+        file_type=QQ_FILE_TYPE_FILE,
+        file_data="ZmFrZQ==",
+        file_name="report.pdf",
+    )
+
+    http = channel._client.api._http
+    assert len(http.calls) == 1
+    payload = http.calls[0][1]["json"]
+    assert payload["file_name"] == "report.pdf"
+    assert payload["file_type"] == QQ_FILE_TYPE_FILE
+
+
+@pytest.mark.asyncio
+async def test_post_base64file_filters_response_to_file_info() -> None:
+    """Response with file_info + extra fields must be filtered to only file_info."""
+    channel = QQChannel(QQConfig(app_id="app", secret="secret"), MessageBus())
+    channel._client = _FakeClient(http_return={
+        "file_info": "fi_123",
+        "file_uuid": "uuid_xxx",
+        "ttl": 3600,
+    })
+
+    result = await channel._post_base64file(
+        chat_id="user1",
+        is_group=False,
+        file_type=QQ_FILE_TYPE_FILE,
+        file_data="ZmFrZQ==",
+        file_name="doc.pdf",
+    )
+
+    assert result == {"file_info": "fi_123"}
+    assert "file_uuid" not in result
+    assert "ttl" not in result
diff --git a/tests/channels/test_wecom_channel.py b/tests/channels/test_wecom_channel.py
new file mode 100644
index 000000000..164c01ea2
--- /dev/null
+++ b/tests/channels/test_wecom_channel.py
@@ -0,0 +1,583 @@
+"""Tests for WeCom channel: helpers, download, upload, send, and message processing."""
+
+import os
+import tempfile
+from pathlib import Path
+from types import SimpleNamespace
+from unittest.mock import AsyncMock, MagicMock, patch
+
+import pytest
+
+try:
+    import importlib.util
+
+    WECOM_AVAILABLE = importlib.util.find_spec("wecom_aibot_sdk") is not None
+except ImportError:
+    WECOM_AVAILABLE = False
+
+if not WECOM_AVAILABLE:
+    pytest.skip("WeCom dependencies not installed (wecom_aibot_sdk)", allow_module_level=True)
+
+from nanobot.bus.events import OutboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.channels.wecom import (
+    WecomChannel,
+    WecomConfig,
+    _guess_wecom_media_type,
+    _sanitize_filename,
+)
+
+# Try to import the real response class; fall back to a stub if unavailable.
+try:
+    from wecom_aibot_sdk.utils import WsResponse
+
+    _RealWsResponse = WsResponse
+except ImportError:
+    _RealWsResponse = None
+
+
+class _FakeResponse:
+    """Minimal stand-in for wecom_aibot_sdk WsResponse."""
+
+    def __init__(self, errcode: int = 0, body: dict | None = None, errmsg: str = "ok"):
+        self.errcode = errcode
+        self.errmsg = errmsg
+        self.body = body or {}
+
+
+class _FakeWsManager:
+    """Tracks send_reply calls and returns configurable responses."""
+
+    def __init__(self, responses: list[_FakeResponse] | None = None):
+        self.responses = responses or []
+        self.calls: list[tuple[str, dict, str]] = []
+        self._idx = 0
+
+    async def send_reply(self, req_id: str, data: dict, cmd: str) -> _FakeResponse:
+        self.calls.append((req_id, data, cmd))
+        if self._idx < len(self.responses):
+            resp = self.responses[self._idx]
+            self._idx += 1
+            return resp
+        return _FakeResponse()
+
+
+class _FakeFrame:
+    """Minimal frame object with a body dict."""
+
+    def __init__(self, body: dict | None = None):
+        self.body = body or {}
+
+
+class _FakeWeComClient:
+    """Fake WeCom client with mock methods."""
+
+    def __init__(self, ws_responses: list[_FakeResponse] | None = None):
+        self._ws_manager = _FakeWsManager(ws_responses)
+        self.download_file = AsyncMock(return_value=(None, None))
+        self.reply = AsyncMock()
+        self.reply_stream = AsyncMock()
+        self.send_message = AsyncMock()
+        self.reply_welcome = AsyncMock()
+
+
+# ── Helper function tests (pure, no async) ──────────────────────────
+
+
+def test_sanitize_filename_strips_path_traversal() -> None:
+    assert _sanitize_filename("../../etc/passwd") == "passwd"
+
+
+def test_sanitize_filename_keeps_chinese_chars() -> None:
+    assert _sanitize_filename("文件（1）.jpg") == "文件（1）.jpg"
+
+
+def test_sanitize_filename_empty_input() -> None:
+    assert _sanitize_filename("") == ""
+
+
+def test_guess_wecom_media_type_image() -> None:
+    for ext in (".jpg", ".jpeg", ".png", ".gif", ".webp", ".bmp"):
+        assert _guess_wecom_media_type(f"photo{ext}") == "image"
+
+
+def test_guess_wecom_media_type_video() -> None:
+    for ext in (".mp4", ".avi", ".mov"):
+        assert _guess_wecom_media_type(f"video{ext}") == "video"
+
+
+def test_guess_wecom_media_type_voice() -> None:
+    for ext in (".amr", ".mp3", ".wav", ".ogg"):
+        assert _guess_wecom_media_type(f"audio{ext}") == "voice"
+
+
+def test_guess_wecom_media_type_file_fallback() -> None:
+    for ext in (".pdf", ".doc", ".xlsx", ".zip"):
+        assert _guess_wecom_media_type(f"doc{ext}") == "file"
+
+
+def test_guess_wecom_media_type_case_insensitive() -> None:
+    assert _guess_wecom_media_type("photo.PNG") == "image"
+    assert _guess_wecom_media_type("photo.Jpg") == "image"
+
+
+# ── _download_and_save_media() ──────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_download_and_save_success() -> None:
+    """Successful download writes file and returns sanitized path."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    fake_data = b"\x89PNG\r\nfake image"
+    client.download_file.return_value = (fake_data, "raw_photo.png")
+
+    with patch("nanobot.channels.wecom.get_media_dir", return_value=Path(tempfile.gettempdir())):
+        path = await channel._download_and_save_media("https://example.com/img.png", "aes_key", "image", "photo.png")
+
+    assert path is not None
+    assert os.path.isfile(path)
+    assert os.path.basename(path) == "photo.png"
+    # Cleanup
+    os.unlink(path)
+
+
+@pytest.mark.asyncio
+async def test_download_and_save_oversized_rejected() -> None:
+    """Data exceeding 200MB is rejected → returns None."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    big_data = b"\x00" * (200 * 1024 * 1024 + 1)  # 200MB + 1 byte
+    client.download_file.return_value = (big_data, "big.bin")
+
+    with patch("nanobot.channels.wecom.get_media_dir", return_value=Path(tempfile.gettempdir())):
+        result = await channel._download_and_save_media("https://example.com/big.bin", "key", "file", "big.bin")
+
+    assert result is None
+
+
+@pytest.mark.asyncio
+async def test_download_and_save_failure() -> None:
+    """SDK returns None data → returns None."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    client.download_file.return_value = (None, None)
+
+    with patch("nanobot.channels.wecom.get_media_dir", return_value=Path(tempfile.gettempdir())):
+        result = await channel._download_and_save_media("https://example.com/fail.png", "key", "image")
+
+    assert result is None
+
+
+# ── _upload_media_ws() ──────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_upload_media_ws_success() -> None:
+    """Happy path: init → chunk → finish → returns (media_id, media_type)."""
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        tmp = f.name
+
+    try:
+        responses = [
+            _FakeResponse(errcode=0, body={"upload_id": "up_1"}),
+            _FakeResponse(errcode=0, body={}),
+            _FakeResponse(errcode=0, body={"media_id": "media_abc"}),
+        ]
+
+        client = _FakeWeComClient(responses)
+        channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+        channel._client = client
+
+        with patch("wecom_aibot_sdk.utils.generate_req_id", side_effect=lambda x: f"req_{x}"):
+            media_id, media_type = await channel._upload_media_ws(client, tmp)
+
+        assert media_id == "media_abc"
+        assert media_type == "image"
+    finally:
+        os.unlink(tmp)
+
+
+@pytest.mark.asyncio
+async def test_upload_media_ws_oversized_file() -> None:
+    """File >200MB triggers ValueError → returns (None, None)."""
+    # Instead of creating a real 200MB+ file, mock os.path.getsize and open
+    with patch("os.path.getsize", return_value=200 * 1024 * 1024 + 1), \
+         patch("builtins.open", MagicMock()):
+        client = _FakeWeComClient()
+        channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+        channel._client = client
+
+        result = await channel._upload_media_ws(client, "/fake/large.bin")
+        assert result == (None, None)
+
+
+@pytest.mark.asyncio
+async def test_upload_media_ws_init_failure() -> None:
+    """Init step returns errcode != 0 → returns (None, None)."""
+    with tempfile.NamedTemporaryFile(suffix=".txt", delete=False) as f:
+        f.write(b"hello")
+        tmp = f.name
+
+    try:
+        responses = [
+            _FakeResponse(errcode=50001, errmsg="invalid"),
+        ]
+
+        client = _FakeWeComClient(responses)
+        channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+        channel._client = client
+
+        with patch("wecom_aibot_sdk.utils.generate_req_id", side_effect=lambda x: f"req_{x}"):
+            result = await channel._upload_media_ws(client, tmp)
+
+        assert result == (None, None)
+    finally:
+        os.unlink(tmp)
+
+
+@pytest.mark.asyncio
+async def test_upload_media_ws_chunk_failure() -> None:
+    """Chunk step returns errcode != 0 → returns (None, None)."""
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        tmp = f.name
+
+    try:
+        responses = [
+            _FakeResponse(errcode=0, body={"upload_id": "up_1"}),
+            _FakeResponse(errcode=50002, errmsg="chunk fail"),
+        ]
+
+        client = _FakeWeComClient(responses)
+        channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+        channel._client = client
+
+        with patch("wecom_aibot_sdk.utils.generate_req_id", side_effect=lambda x: f"req_{x}"):
+            result = await channel._upload_media_ws(client, tmp)
+
+        assert result == (None, None)
+    finally:
+        os.unlink(tmp)
+
+
+@pytest.mark.asyncio
+async def test_upload_media_ws_finish_no_media_id() -> None:
+    """Finish step returns empty media_id → returns (None, None)."""
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        tmp = f.name
+
+    try:
+        responses = [
+            _FakeResponse(errcode=0, body={"upload_id": "up_1"}),
+            _FakeResponse(errcode=0, body={}),
+            _FakeResponse(errcode=0, body={}),  # no media_id
+        ]
+
+        client = _FakeWeComClient(responses)
+        channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+        channel._client = client
+
+        with patch("wecom_aibot_sdk.utils.generate_req_id", side_effect=lambda x: f"req_{x}"):
+            result = await channel._upload_media_ws(client, tmp)
+
+        assert result == (None, None)
+    finally:
+        os.unlink(tmp)
+
+
+# ── send() ──────────────────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_send_text_with_frame() -> None:
+    """When frame is stored, send uses reply_stream for final text."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+    channel._generate_req_id = lambda x: f"req_{x}"
+    channel._chat_frames["chat1"] = _FakeFrame()
+
+    await channel.send(
+        OutboundMessage(channel="wecom", chat_id="chat1", content="hello")
+    )
+
+    client.reply_stream.assert_called_once()
+    call_args = client.reply_stream.call_args
+    assert call_args[0][2] == "hello"  # content arg
+
+
+@pytest.mark.asyncio
+async def test_send_progress_with_frame() -> None:
+    """When metadata has _progress, send uses reply (not reply_stream)."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+    channel._chat_frames["chat1"] = _FakeFrame()
+
+    await channel.send(
+        OutboundMessage(channel="wecom", chat_id="chat1", content="thinking...", metadata={"_progress": True})
+    )
+
+    client.reply.assert_called_once()
+    client.reply_stream.assert_not_called()
+    call_args = client.reply.call_args
+    assert call_args[0][1]["text"]["content"] == "thinking..."
+
+
+@pytest.mark.asyncio
+async def test_send_proactive_without_frame() -> None:
+    """Without stored frame, send uses send_message with markdown."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    await channel.send(
+        OutboundMessage(channel="wecom", chat_id="chat1", content="proactive msg")
+    )
+
+    client.send_message.assert_called_once()
+    call_args = client.send_message.call_args
+    assert call_args[0][0] == "chat1"
+    assert call_args[0][1]["msgtype"] == "markdown"
+
+
+@pytest.mark.asyncio
+async def test_send_media_then_text() -> None:
+    """Media files are uploaded and sent before text content."""
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        tmp = f.name
+
+    try:
+        responses = [
+            _FakeResponse(errcode=0, body={"upload_id": "up_1"}),
+            _FakeResponse(errcode=0, body={}),
+            _FakeResponse(errcode=0, body={"media_id": "media_123"}),
+        ]
+
+        channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+        client = _FakeWeComClient(responses)
+        channel._client = client
+        channel._generate_req_id = lambda x: f"req_{x}"
+        channel._chat_frames["chat1"] = _FakeFrame()
+
+        await channel.send(
+            OutboundMessage(channel="wecom", chat_id="chat1", content="see image", media=[tmp])
+        )
+
+        # Media should have been sent via reply
+        media_calls = [c for c in client.reply.call_args_list if c[0][1].get("msgtype") == "image"]
+        assert len(media_calls) == 1
+        assert media_calls[0][0][1]["image"]["media_id"] == "media_123"
+
+        # Text should have been sent via reply_stream
+        client.reply_stream.assert_called_once()
+    finally:
+        os.unlink(tmp)
+
+
+@pytest.mark.asyncio
+async def test_send_media_file_not_found() -> None:
+    """Non-existent media path is skipped with a warning."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+    channel._generate_req_id = lambda x: f"req_{x}"
+    channel._chat_frames["chat1"] = _FakeFrame()
+
+    await channel.send(
+        OutboundMessage(channel="wecom", chat_id="chat1", content="hello", media=["/nonexistent/file.png"])
+    )
+
+    # reply_stream should still be called for the text part
+    client.reply_stream.assert_called_once()
+    # No media reply should happen
+    media_calls = [c for c in client.reply.call_args_list if c[0][1].get("msgtype") in ("image", "file", "video")]
+    assert len(media_calls) == 0
+
+
+@pytest.mark.asyncio
+async def test_send_exception_caught_not_raised() -> None:
+    """Exceptions inside send() must not propagate."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+    channel._generate_req_id = lambda x: f"req_{x}"
+    channel._chat_frames["chat1"] = _FakeFrame()
+
+    # Make reply_stream raise
+    client.reply_stream.side_effect = RuntimeError("boom")
+
+    await channel.send(
+        OutboundMessage(channel="wecom", chat_id="chat1", content="fail test")
+    )
+    # No exception — test passes if we reach here.
+
+
+# ── _process_message() ──────────────────────────────────────────────
+
+
+@pytest.mark.asyncio
+async def test_process_text_message() -> None:
+    """Text message is routed to bus with correct fields."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["user1"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    frame = _FakeFrame(body={
+        "msgid": "msg_text_1",
+        "chatid": "chat1",
+        "chattype": "single",
+        "from": {"userid": "user1"},
+        "text": {"content": "hello wecom"},
+    })
+
+    await channel._process_message(frame, "text")
+
+    msg = await channel.bus.consume_inbound()
+    assert msg.sender_id == "user1"
+    assert msg.chat_id == "chat1"
+    assert msg.content == "hello wecom"
+    assert msg.metadata["msg_type"] == "text"
+
+
+@pytest.mark.asyncio
+async def test_process_image_message() -> None:
+    """Image message: download success → media_paths non-empty."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["user1"]), MessageBus())
+    client = _FakeWeComClient()
+
+    with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
+        f.write(b"\x89PNG\r\n")
+        saved = f.name
+
+    client.download_file.return_value = (b"\x89PNG\r\n", "photo.png")
+    channel._client = client
+
+    try:
+        with patch("nanobot.channels.wecom.get_media_dir", return_value=Path(os.path.dirname(saved))):
+            frame = _FakeFrame(body={
+                "msgid": "msg_img_1",
+                "chatid": "chat1",
+                "from": {"userid": "user1"},
+                "image": {"url": "https://example.com/img.png", "aeskey": "key123"},
+            })
+            await channel._process_message(frame, "image")
+
+        msg = await channel.bus.consume_inbound()
+        assert len(msg.media) == 1
+        assert msg.media[0].endswith("photo.png")
+        assert "[image:" in msg.content
+    finally:
+        if os.path.exists(saved):
+            pass  # may have been overwritten; clean up if exists
+        # Clean up any photo.png in tempdir
+        p = os.path.join(os.path.dirname(saved), "photo.png")
+        if os.path.exists(p):
+            os.unlink(p)
+
+
+@pytest.mark.asyncio
+async def test_process_file_message() -> None:
+    """File message: download success → media_paths non-empty (critical fix verification)."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["user1"]), MessageBus())
+    client = _FakeWeComClient()
+
+    with tempfile.NamedTemporaryFile(suffix=".pdf", delete=False) as f:
+        f.write(b"%PDF-1.4 fake")
+        saved = f.name
+
+    client.download_file.return_value = (b"%PDF-1.4 fake", "report.pdf")
+    channel._client = client
+
+    try:
+        with patch("nanobot.channels.wecom.get_media_dir", return_value=Path(os.path.dirname(saved))):
+            frame = _FakeFrame(body={
+                "msgid": "msg_file_1",
+                "chatid": "chat1",
+                "from": {"userid": "user1"},
+                "file": {"url": "https://example.com/report.pdf", "aeskey": "key456", "name": "report.pdf"},
+            })
+            await channel._process_message(frame, "file")
+
+        msg = await channel.bus.consume_inbound()
+        assert len(msg.media) == 1
+        assert msg.media[0].endswith("report.pdf")
+        assert "[file: report.pdf]" in msg.content
+    finally:
+        p = os.path.join(os.path.dirname(saved), "report.pdf")
+        if os.path.exists(p):
+            os.unlink(p)
+
+
+@pytest.mark.asyncio
+async def test_process_voice_message() -> None:
+    """Voice message: transcribed text is included in content."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["user1"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    frame = _FakeFrame(body={
+        "msgid": "msg_voice_1",
+        "chatid": "chat1",
+        "from": {"userid": "user1"},
+        "voice": {"content": "transcribed text here"},
+    })
+
+    await channel._process_message(frame, "voice")
+
+    msg = await channel.bus.consume_inbound()
+    assert "transcribed text here" in msg.content
+    assert "[voice]" in msg.content
+
+
+@pytest.mark.asyncio
+async def test_process_message_deduplication() -> None:
+    """Same msg_id is not processed twice."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["user1"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    frame = _FakeFrame(body={
+        "msgid": "msg_dup_1",
+        "chatid": "chat1",
+        "from": {"userid": "user1"},
+        "text": {"content": "once"},
+    })
+
+    await channel._process_message(frame, "text")
+    await channel._process_message(frame, "text")
+
+    msg = await channel.bus.consume_inbound()
+    assert msg.content == "once"
+
+    # Second message should not appear on the bus
+    assert channel.bus.inbound.empty()
+
+
+@pytest.mark.asyncio
+async def test_process_message_empty_content_skipped() -> None:
+    """Message with empty content produces no bus message."""
+    channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["user1"]), MessageBus())
+    client = _FakeWeComClient()
+    channel._client = client
+
+    frame = _FakeFrame(body={
+        "msgid": "msg_empty_1",
+        "chatid": "chat1",
+        "from": {"userid": "user1"},
+        "text": {"content": ""},
+    })
+
+    await channel._process_message(frame, "text")
+
+    assert channel.bus.inbound.empty()