fix(webui): render local CLI image artifacts

tests/channels/test_websocket_channel.py

@@ -480,6 +480,38 @@ async def test_send_delta_emits_delta_and_stream_end() -> None:
     assert second["stream_id"] == "sid"
 
 
+@pytest.mark.asyncio
+async def test_send_delta_stream_end_rewrites_local_markdown_image(monkeypatch, tmp_path) -> None:
+    bus = MagicMock()
+    workspace = tmp_path / "workspace"
+    workspace.mkdir()
+    (workspace / "diagram.png").write_bytes(b"\x89PNG\r\n\x1a\nimage")
+    media = tmp_path / "media"
+
+    def fake_media_dir(channel: str | None = None):
+        path = media / channel if channel else media
+        path.mkdir(parents=True, exist_ok=True)
+        return path
+
+    monkeypatch.setattr("nanobot.channels.websocket.get_media_dir", fake_media_dir)
+    channel = WebSocketChannel(
+        {"enabled": True, "allowFrom": ["*"], "streaming": True},
+        bus,
+        workspace_path=workspace,
+    )
+    mock_ws = AsyncMock()
+    channel._attach(mock_ws, "chat-1")
+
+    await channel.send_delta("chat-1", "![Diagram](", {"_stream_delta": True, "_stream_id": "sid"})
+    await channel.send_delta("chat-1", "diagram.png)", {"_stream_delta": True, "_stream_id": "sid"})
+    await channel.send_delta("chat-1", "", {"_stream_end": True, "_stream_id": "sid"})
+
+    assert mock_ws.send.await_count == 3
+    final = json.loads(mock_ws.send.call_args_list[2][0][0])
+    assert final["event"] == "stream_end"
+    assert final["text"].startswith("![Diagram](/api/media/")
+
+
 @pytest.mark.asyncio
 async def test_send_reasoning_delta_emits_streaming_frame() -> None:
     bus = MagicMock()

tests/channels/test_websocket_media_route.py

@@ -44,6 +44,7 @@ def _ch(
     bus: Any,
     *,
     session_manager: SessionManager | None = None,
+    workspace_path: Path | None = None,
     port: int,
 ) -> WebSocketChannel:
     return WebSocketChannel(
@@ -57,6 +58,7 @@ def _ch(
         },
         bus,
         session_manager=session_manager,
+        workspace_path=workspace_path,
     )
 
 
@@ -67,6 +69,15 @@ def bus() -> MagicMock:
     return b
 
 
+def _fake_media_dir(root: Path):
+    def inner(channel: str | None = None) -> Path:
+        path = root / channel if channel else root
+        path.mkdir(parents=True, exist_ok=True)
+        return path
+
+    return inner
+
+
 async def _http_get(
     url: str, headers: dict[str, str] | None = None
 ) -> httpx.Response:
@@ -123,6 +134,45 @@ def test_sign_media_path_round_trips_via_hmac(
     assert _b64url_decode(payload).decode() == "a.png"
 
 
+def test_local_markdown_image_is_staged_and_rewritten(
+    bus: MagicMock,
+    tmp_path: Path,
+) -> None:
+    workspace = tmp_path / "workspace"
+    workspace.mkdir()
+    (workspace / "demo_arch.png").write_bytes(_PNG_BYTES)
+    media = tmp_path / "media"
+    channel = _ch(bus, workspace_path=workspace, port=0)
+
+    with patch("nanobot.channels.websocket.get_media_dir", side_effect=_fake_media_dir(media)):
+        rewritten = channel._rewrite_local_markdown_images(
+            "The result:\n![Cloud Architecture Diagram](demo_arch.png)"
+        )
+
+    assert "![Cloud Architecture Diagram](/api/media/" in rewritten
+    staged = list((media / "websocket").iterdir())
+    assert len(staged) == 1
+    assert staged[0].read_bytes() == _PNG_BYTES
+
+
+def test_local_markdown_image_rejects_workspace_escape(
+    bus: MagicMock,
+    tmp_path: Path,
+) -> None:
+    workspace = tmp_path / "workspace"
+    workspace.mkdir()
+    outside = tmp_path / "outside.png"
+    outside.write_bytes(_PNG_BYTES)
+    media = tmp_path / "media"
+    channel = _ch(bus, workspace_path=workspace, port=0)
+    text = "![nope](../outside.png)"
+
+    with patch("nanobot.channels.websocket.get_media_dir", side_effect=_fake_media_dir(media)):
+        assert channel._rewrite_local_markdown_images(text) == text
+
+    assert not (media / "websocket").exists()
+
+
 # ---------------------------------------------------------------------------
 # /api/media/<sig>/<payload>: the serving handler
 # ---------------------------------------------------------------------------