codeant-ai-for-open-source[bot] commented on code in PR #44558:
URL: https://github.com/apache/superset/pull/44558#discussion_r4079761566


##########
superset/mcp_service/chart/tool/get_chart_preview.py:
##########
@@ -1087,6 +1094,100 @@ def generate(
         return strategy.generate()
 
 
+async def _generate_png_preview(
+    chart_id: int, request: GetChartPreviewRequest
+) -> PNGPreview | ChartError:
+    """Render saved charts as the caller in an isolated browser and app 
context."""
+    if (
+        not chart_id
+        or request.form_data_key
+        or request.extra_form_data
+        or guest_scope.is_guest_read()
+    ):
+        return ChartError(
+            error="PNG previews require a saved chart and a non-guest user, "
+            "without unsaved state or extra filters.",
+            error_type="UnsupportedFormat",
+        )
+    user_id = getattr(getattr(g, "user", None), "id", None)
+    if not isinstance(user_id, int):
+        return ChartError(error="Authentication required", 
error_type="Forbidden")
+    width = 800 if request.width is None else request.width
+    height = 600 if request.height is None else request.height
+    if not (64 <= width <= 4096 and 64 <= height <= 4096):
+        return ChartError(
+            error="PNG dimensions must be between 64 and 4096 pixels.",
+            error_type="ValidationError",
+        )
+
+    def render() -> PNGPreview | ChartError:
+        from superset import is_feature_enabled
+        from superset.mcp_service.auth import _mcp_tool_call_context
+        from superset.utils.core import override_user
+        from superset.utils.screenshots import validate_screenshot_image
+        from superset.utils.urls import get_url_path
+        from superset.utils.webdriver import (
+            _PlaywrightBrowserManager,
+            WebDriverPlaywright,
+        )
+
+        # Resolve ORM objects in a fresh context; neither the request session 
nor
+        # Flask's mutable g is shared with the rendering worker.
+        with _mcp_tool_call_context():
+            user = security_manager.find_user(id=user_id)
+            if user is None or not user.is_active:
+                return ChartError(
+                    error="Authentication required", error_type="Forbidden"
+                )
+            with override_user(user):
+                chart = find_chart_by_identifier(chart_id)
+                if chart is None:
+                    return ChartError(error="Chart not found", 
error_type="NotFound")
+                security_manager.raise_for_access(chart=chart)
+                if is_feature_enabled(
+                    "GRANULAR_EXPORT_CONTROLS"
+                ) and not security_manager.can_access("can_export_image", 
"Superset"):
+                    return ChartError(
+                        error="Image export is not permitted", 
error_type="Forbidden"
+                    )
+                url = get_url_path(
+                    "Superset.slice", slice_id=chart_id, standalone="true"
+                )
+                manager = _PlaywrightBrowserManager()
+                try:
+                    driver = WebDriverPlaywright(
+                        "",
+                        (width, height),
+                        require_complete_capture=True,
+                        browser_manager=manager,
+                    )
+                    image = driver.get_screenshot(url, "chart-container", 
user=user)
+                    if (
+                        image is None
+                        or not image.startswith(b"\x89PNG\r\n\x1a\n")
+                        or validate_screenshot_image(image)
+                    ):
+                        return ChartError(
+                            error="Chart rendering failed", 
error_type="RenderError"
+                        )
+                    with Image.open(BytesIO(image)) as rendered:
+                        image_width, image_height = rendered.size
+                    return PNGPreview(
+                        data=base64.b64encode(image).decode("ascii"),
+                        width=image_width,
+                        height=image_height,
+                    )
+                finally:
+                    manager._cleanup()
+
+    try:
+        return await asyncio.to_thread(render)

Review Comment:
   ✅ **Customized review instruction saved!**
   
   **Instruction:**
   > Do not flag cancellation-related resource leaks for the bounded render 
operation in this module when the screenshot call has its own timeout and 
browser resources are released in a finally cleanup block; early process 
isolation is out of scope.
   
   **Applied to:**
     - `superset/mcp_service/chart/tool/get_chart_preview.py`
   
   ---
   💡 *To manage or update this instruction, visit: [CodeAnt AI 
Settings](https://app.codeant.ai/org/settings/learnings)*



##########
superset/mcp_service/chart/tool/get_chart_preview.py:
##########
@@ -1087,6 +1094,100 @@ def generate(
         return strategy.generate()
 
 
+async def _generate_png_preview(
+    chart_id: int, request: GetChartPreviewRequest
+) -> PNGPreview | ChartError:
+    """Render saved charts as the caller in an isolated browser and app 
context."""
+    if (
+        not chart_id
+        or request.form_data_key
+        or request.extra_form_data
+        or guest_scope.is_guest_read()
+    ):
+        return ChartError(
+            error="PNG previews require a saved chart and a non-guest user, "
+            "without unsaved state or extra filters.",
+            error_type="UnsupportedFormat",
+        )
+    user_id = getattr(getattr(g, "user", None), "id", None)
+    if not isinstance(user_id, int):
+        return ChartError(error="Authentication required", 
error_type="Forbidden")
+    width = 800 if request.width is None else request.width
+    height = 600 if request.height is None else request.height
+    if not (64 <= width <= 4096 and 64 <= height <= 4096):
+        return ChartError(
+            error="PNG dimensions must be between 64 and 4096 pixels.",
+            error_type="ValidationError",
+        )
+
+    def render() -> PNGPreview | ChartError:
+        from superset import is_feature_enabled
+        from superset.mcp_service.auth import _mcp_tool_call_context
+        from superset.utils.core import override_user
+        from superset.utils.screenshots import validate_screenshot_image
+        from superset.utils.urls import get_url_path
+        from superset.utils.webdriver import (
+            _PlaywrightBrowserManager,
+            WebDriverPlaywright,
+        )
+
+        # Resolve ORM objects in a fresh context; neither the request session 
nor
+        # Flask's mutable g is shared with the rendering worker.
+        with _mcp_tool_call_context():
+            user = security_manager.find_user(id=user_id)
+            if user is None or not user.is_active:
+                return ChartError(
+                    error="Authentication required", error_type="Forbidden"
+                )
+            with override_user(user):
+                chart = find_chart_by_identifier(chart_id)
+                if chart is None:
+                    return ChartError(error="Chart not found", 
error_type="NotFound")
+                security_manager.raise_for_access(chart=chart)

Review Comment:
   ✅ **CodeAnt verified this suggestion was addressed in subsequent commits and 
marked this thread resolved** as of `3522c87`.
   
   Added a dedicated `except SupersetSecurityException` handler around the 
render call, returning a `ChartError` with `error_type="Forbidden"` instead of 
treating the denial as a rendering failure.
   
   <sub>If that's not right, unresolve this thread and CodeAnt will leave it 
open.</sub>
   
   <!-- codeant-auto-resolve-reply -->



##########
tests/unit_tests/mcp_service/chart/tool/test_get_chart_preview.py:
##########
@@ -1839,3 +1839,250 @@ def 
test_saved_gauge_preview_skips_empty_aggregate_groups(
     else:
         assert "Blue" in result.ascii_content
         assert "Empty" not in result.ascii_content
+
+
[email protected]
[email protected]("user_id", [11, 29])
+async def test_png_preview_renders_as_caller_in_isolated_context(app_context, 
user_id):
+    import base64
+    import threading
+    from io import BytesIO
+
+    from flask import g
+    from PIL import Image
+
+    module = importlib.import_module(
+        "superset.mcp_service.chart.tool.get_chart_preview"
+    )
+    caller_thread = threading.get_ident()
+    g.user = SimpleNamespace(id=user_id)
+    g.request_marker = "request-only"
+    user = SimpleNamespace(id=user_id, is_active=True)
+    chart = SimpleNamespace(id=104)
+    png = BytesIO()
+    Image.new("RGB", (80, 60), "white").save(png, format="PNG")
+
+    def screenshot(url, element, *, user):
+        assert threading.get_ident() != caller_thread
+        assert g.user.id == user_id
+        assert not hasattr(g, "request_marker")
+        assert user.id == user_id
+        assert url == "http://localhost/superset/slice/104/?standalone=true";
+        assert element == "chart-container"
+        return png.getvalue()
+
+    with (
+        patch.object(module, "security_manager", new=MagicMock()) as manager,
+        patch.object(module, "find_chart_by_identifier", return_value=chart),
+        patch.object(module.guest_scope, "is_guest_read", return_value=False),
+        patch("superset.is_feature_enabled", return_value=False),
+        patch(
+            "superset.utils.urls.get_url_path",
+            
return_value="http://localhost/superset/slice/104/?standalone=true";,
+        ),
+        patch("superset.utils.webdriver._PlaywrightBrowserManager") as 
browser_manager,
+        patch("superset.utils.webdriver.WebDriverPlaywright") as driver,
+    ):
+        manager.find_user.return_value = user
+        driver.return_value.get_screenshot.side_effect = screenshot
+        result = await module._generate_png_preview(
+            104, GetChartPreviewRequest(identifier=104, format="png")
+        )
+        assert base64.b64decode(result.data) == png.getvalue()
+        assert (result.width, result.height) == (80, 60)
+        manager.raise_for_access.assert_called_once_with(chart=chart)
+        browser_manager.return_value._cleanup.assert_called_once()
+        assert (
+            driver.call_args.kwargs["browser_manager"] is 
browser_manager.return_value
+        )
+        assert g.request_marker == "request-only"
+        assert g.user.id == user_id
+
+
[email protected]
[email protected](
+    "guest,kwargs",
+    [
+        (True, {}),
+        (False, {"form_data_key": "unsaved"}),
+        (False, {"extra_form_data": {"filters": []}}),
+    ],
+)
+async def test_png_preview_rejects_unpropagated_context(app_context, guest, 
kwargs):
+    module = importlib.import_module(
+        "superset.mcp_service.chart.tool.get_chart_preview"
+    )
+    with (
+        patch.object(module.guest_scope, "is_guest_read", return_value=guest),
+        patch("superset.utils.webdriver._PlaywrightBrowserManager") as manager,
+    ):
+        result = await module._generate_png_preview(
+            104, GetChartPreviewRequest(identifier=104, format="png", **kwargs)
+        )
+        assert result.error_type == "UnsupportedFormat"
+        manager.assert_not_called()
+
+
[email protected]
[email protected]("failure", ["denied", "missing", "inactive", 
"export"])
+async def test_png_preview_authorizes_before_browser(app_context, failure):
+    from flask import g
+
+    module = importlib.import_module(
+        "superset.mcp_service.chart.tool.get_chart_preview"
+    )
+    g.user = SimpleNamespace(id=11)
+    with (
+        patch.object(module, "security_manager", new=MagicMock()) as manager,
+        patch.object(
+            module,
+            "find_chart_by_identifier",
+            return_value=None if failure == "missing" else 
SimpleNamespace(id=104),
+        ),
+        patch.object(module.guest_scope, "is_guest_read", return_value=False),
+        patch("superset.is_feature_enabled", return_value=failure == "export"),
+        patch("superset.utils.webdriver._PlaywrightBrowserManager") as browser,
+    ):
+        manager.find_user.return_value = SimpleNamespace(
+            id=11, is_active=failure != "inactive"
+        )
+        manager.can_access.return_value = False
+        if failure == "denied":
+            manager.raise_for_access.side_effect = ValueError("secret denied 
URL")
+        result = await module._generate_png_preview(
+            104, GetChartPreviewRequest(identifier=104, format="png")
+        )
+        assert isinstance(result, ChartError)
+        assert "secret" not in result.error
+        browser.assert_not_called()

Review Comment:
   ✅ **CodeAnt verified this suggestion was addressed in subsequent commits and 
marked this thread resolved** as of `3522c87`.
   
   The denied-case test now explicitly asserts `result.error_type == 
"Forbidden"` while still verifying that sensitive error text is not exposed.
   
   <sub>If that's not right, unresolve this thread and CodeAnt will leave it 
open.</sub>
   
   <!-- codeant-auto-resolve-reply -->



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