fix(mcp): expose table column formatting

superset/mcp_service/chart/chart_utils.py

@@ -24,6 +24,7 @@
 
 import hashlib
 import logging
+from collections.abc import Mapping
 from dataclasses import dataclass
 from typing import Any, Dict, TYPE_CHECKING
 
@@ -570,10 +571,48 @@ def map_table_config(config: TableChartConfig) -> Dict[str, Any]:
 
     form_data["row_limit"] = config.row_limit
     add_color_scheme(form_data, config.color_scheme)
+    if config.column_config is not None:
+        form_data["column_config"] = {
+            label: column.model_dump(by_alias=True, exclude_none=True)
+            for label, column in config.column_config.items()
+        }
 
     return form_data
 
 
+def merge_table_column_config(
+    existing_form_data: Mapping[str, Any], new_form_data: Dict[str, Any]
+) -> None:
+    """Merge MCP table formatting without discarding UI-only settings.
+
+    An omitted ``column_config`` preserves the saved value, an explicit empty
+    mapping clears it, and a non-empty mapping updates only the supplied labels
+    and properties. The nested merge is important because the Superset UI stores
+    additional column settings that the MCP schema does not expose.
+    """
+    if "column_config" not in new_form_data:
+        if "column_config" in existing_form_data:
+            new_form_data["column_config"] = existing_form_data["column_config"]
+        return
+
+    new_column_config = new_form_data["column_config"]
+    if not isinstance(new_column_config, dict) or not new_column_config:
+        return
+
+    existing_column_config = existing_form_data.get("column_config")
+    if not isinstance(existing_column_config, dict):
+        return
+
+    merged_column_config = dict(existing_column_config)
+    for label, settings in new_column_config.items():
+        existing_settings = existing_column_config.get(label)
+        if isinstance(existing_settings, dict) and isinstance(settings, dict):
+            merged_column_config[label] = {**existing_settings, **settings}
+        else:
+            merged_column_config[label] = settings
+    new_form_data["column_config"] = merged_column_config
+
+
 def create_metric_object(col: ColumnRef) -> Dict[str, Any] | str:
     """Create a metric object for a column with enhanced validation.
 

superset/mcp_service/chart/schemas.py

@@ -1540,6 +1540,37 @@ def validate_metric_aggregate(self) -> Self:
         return self
 
 
+class TableColumnConfig(UnknownFieldCheckMixin):
+    """Display formatting supported by the MCP table-chart schema."""
+
+    model_config = ConfigDict(
+        extra="ignore",
+        populate_by_name=True,
+        json_schema_extra={"additionalProperties": False},
+    )
+
+    column_width: int | None = Field(
+        None,
+        alias="columnWidth",
+        description="Minimum column width in pixels.",
+        ge=0,
+    )
+    d3_number_format: str | None = Field(
+        None,
+        alias="d3NumberFormat",
+        description="D3 number format, for example ',.2f', '$,.2f', or '.1%'.",
+        min_length=1,
+        max_length=100,
+    )
+    d3_time_format: str | None = Field(
+        None,
+        alias="d3TimeFormat",
+        description="D3 time format, for example '%Y-%m-%d' or '%b %d, %Y'.",
+        min_length=1,
+        max_length=100,
+    )
+
+
 class TableChartConfig(UnknownFieldCheckMixin):
     model_config = ConfigDict(extra="ignore", populate_by_name=True)
 
@@ -1586,6 +1617,18 @@ class TableChartConfig(UnknownFieldCheckMixin):
         ),
         max_length=100,
     )
+    column_config: dict[str, "TableColumnConfig"] | None = Field(
+        None,
+        description=(
+            "Per-column display settings, keyed by the result column label "
+            "(for a raw column this is usually its column name; for a metric, use "
+            "its label). Use columnWidth for minimum width in pixels, "
+            "d3NumberFormat for D3 number formats such as ',.2f' or '.1%', and "
+            "d3TimeFormat for D3 time formats such as '%Y-%m-%d'. Example: "
+            "{'Total Sales': {'columnWidth': 120, 'd3NumberFormat': '$,.2f'}, "
+            "'Order Date': {'d3TimeFormat': '%Y-%m-%d'}}."
+        ),
+    )
 
     @model_validator(mode="after")
     def reject_sql_expression_in_raw_mode(self) -> "TableChartConfig":

superset/mcp_service/chart/tool/update_chart.py

@@ -39,6 +39,7 @@
     analyze_chart_semantics,
     generate_chart_name,
     map_config_to_form_data,
+    merge_table_column_config,
 )
 from superset.mcp_service.chart.compile import validate_and_compile
 from superset.mcp_service.chart.schemas import (
@@ -59,6 +60,20 @@
 logger = logging.getLogger(__name__)
 
 
+def _get_existing_form_data(chart: Any) -> dict[str, Any]:
+    """Return a chart's saved form data, treating malformed params as empty."""
+    if not getattr(chart, "params", None):
+        return {}
+    try:
+        parsed = json.loads(chart.params)
+    except (ValueError, TypeError):
+        parsed = None
+    if not isinstance(parsed, dict):
+        logger.warning("Failed to parse existing chart.params for chart %s", chart.id)
+        return {}
+    return parsed
+
+
 def _validation_error_response(message: str, details: str) -> GenerateChartResponse:
     return GenerateChartResponse.model_validate(
         {
@@ -117,6 +132,7 @@ def _build_update_payload(
             parsed_config, dataset_id=effective_dataset_id
         )
         new_form_data.pop("_mcp_warnings", None)
+        merge_table_column_config(_get_existing_form_data(chart), new_form_data)
 
         chart_name = (
             request.chart_name
@@ -164,15 +180,7 @@ def _build_preview_form_data(
     GenerateChartResponse error when neither config nor chart_name is given.
     ``parsed_config`` is the pre-parsed chart config from the caller.
     """
-    existing_form_data: dict[str, Any] = {}
-    if getattr(chart, "params", None):
-        try:
-            existing_form_data = json.loads(chart.params) or {}
-        except (ValueError, TypeError):
-            logger.warning(
-                "Failed to parse existing chart.params for chart %s", chart.id
-            )
-            existing_form_data = {}
+    existing_form_data = _get_existing_form_data(chart)
 
     effective_dataset_id = (
         request.dataset_id
@@ -185,6 +193,7 @@ def _build_preview_form_data(
             parsed_config, dataset_id=effective_dataset_id
         )
         new_form_data.pop("_mcp_warnings", None)
+        merge_table_column_config(existing_form_data, new_form_data)
         merged = {**existing_form_data, **new_form_data}
     else:
         if not request.chart_name and request.dataset_id is None:

superset/mcp_service/chart/tool/update_chart_preview.py

@@ -38,6 +38,7 @@
     generate_chart_name,
     generate_explore_link,
     map_config_to_form_data,
+    merge_table_column_config,
 )
 from superset.mcp_service.chart.compile import validate_and_compile
 from superset.mcp_service.chart.preview_utils import (
@@ -186,6 +187,8 @@ def update_chart_preview(  # noqa: C901
                 old_adhoc_filters = previous_form_data.get("adhoc_filters")
                 if old_adhoc_filters:
                     new_form_data["adhoc_filters"] = old_adhoc_filters
+            if previous_form_data:
+                merge_table_column_config(previous_form_data, new_form_data)
 
             # Tier-1 schema validation against the dataset (no DB roundtrip).
             # Runs AFTER the filter merge so filter columns are also validated.

tests/unit_tests/mcp_service/chart/test_chart_utils.py

@@ -38,6 +38,7 @@
     map_filter_operator,
     map_table_config,
     map_xy_config,
+    merge_table_column_config,
     validate_chart_dataset,
 )
 from superset.mcp_service.chart.schemas import (
@@ -144,6 +145,43 @@ def test_map_filter_operator_unknown(self) -> None:
         assert map_filter_operator("UNKNOWN") == "UNKNOWN"
 
 
+class TestMergeTableColumnConfig:
+    def test_partial_update_preserves_other_labels_and_settings(self) -> None:
+        existing = {
+            "column_config": {
+                "Revenue": {"columnWidth": 80, "visible": False},
+                "Region": {"customColumnName": "Sales region"},
+            }
+        }
+        updated = {
+            "column_config": {
+                "Revenue": {"columnWidth": 120, "d3NumberFormat": "$,.2f"}
+            }
+        }
+
+        merge_table_column_config(existing, updated)
+
+        assert updated["column_config"] == {
+            "Revenue": {
+                "columnWidth": 120,
+                "d3NumberFormat": "$,.2f",
+                "visible": False,
+            },
+            "Region": {"customColumnName": "Sales region"},
+        }
+
+    def test_omitted_preserves_and_explicit_empty_clears(self) -> None:
+        existing = {"column_config": {"Revenue": {"columnWidth": 80}}}
+        omitted: dict[str, Any] = {}
+        explicit_empty: dict[str, Any] = {"column_config": {}}
+
+        merge_table_column_config(existing, omitted)
+        merge_table_column_config(existing, explicit_empty)
+
+        assert omitted["column_config"] == existing["column_config"]
+        assert explicit_empty["column_config"] == {}
+
+
 class TestMapTableConfig:
     """Test map_table_config function"""
 

tests/unit_tests/mcp_service/chart/test_new_chart_types.py

@@ -1240,6 +1240,41 @@ def test_color_scheme_omitted_when_unset(self) -> None:
 
         assert "color_scheme" not in result
 
+    def test_column_config_in_form_data(self) -> None:
+        config = TableChartConfig.model_validate(
+            {
+                "chart_type": "table",
+                "columns": [
+                    {"name": "order_date"},
+                    {"name": "revenue", "aggregate": "SUM", "label": "Revenue"},
+                ],
+                "column_config": {
+                    "order_date": {
+                        "columnWidth": 120,
+                        "d3TimeFormat": "%Y-%m-%d",
+                    },
+                    "Revenue": {"d3NumberFormat": "$,.2f"},
+                },
+            }
+        )
+
+        result = map_table_config(config)
+
+        assert result["column_config"] == {
+            "order_date": {"columnWidth": 120, "d3TimeFormat": "%Y-%m-%d"},
+            "Revenue": {"d3NumberFormat": "$,.2f"},
+        }
+
+    def test_column_config_rejects_unknown_setting(self) -> None:
+        with pytest.raises(ValidationError, match="Unknown field 'width'"):
+            TableChartConfig.model_validate(
+                {
+                    "chart_type": "table",
+                    "columns": [{"name": "product"}],
+                    "column_config": {"product": {"width": 120}},
+                }
+            )
+
 
 class TestCurrencyFormatModel:
     """CurrencyFormat schema validation."""

tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py

@@ -44,10 +44,17 @@ def test_xy_schema_has_expected_fields(self) -> None:
         assert "y" in props
         assert "kind" in props
 
-    def test_table_schema_has_columns(self) -> None:
+    def test_table_schema_has_columns_and_column_config(self) -> None:
         result = _call_schema("table")
         props = result["schema"]["properties"]
         assert "columns" in props
+        assert "column_config" in props
+        description = props["column_config"]["description"]
+        assert "columnWidth" in description
+        assert "d3NumberFormat" in description
+        assert "d3TimeFormat" in description
+        column_config_schema = result["schema"]["$defs"]["TableColumnConfig"]
+        assert column_config_schema["additionalProperties"] is False
 
     def test_pie_schema_has_dimension_metric(self) -> None:
         result = _call_schema("pie")