From 8d95b8f4fbb669216ebe43b5fd2a6da356bafc56 Mon Sep 17 00:00:00 2001
From: Amin Ghadersohi <amin.ghadersohi@gmail.com>
Date: Fri, 31 Jul 2026 21:39:03 +0000
Subject: [PATCH 1/2] fix(mcp): expose table column formatting

---
 superset/mcp_service/chart/chart_utils.py     |  5 +++
 superset/mcp_service/chart/schemas.py         | 39 +++++++++++++++++++
 .../mcp_service/chart/tool/update_chart.py    |  7 ++++
 .../chart/tool/update_chart_preview.py        |  4 ++
 .../mcp_service/chart/test_new_chart_types.py | 35 +++++++++++++++++
 .../chart/tool/test_get_chart_type_schema.py  |  7 +++-
 .../chart/tool/test_update_chart.py           | 20 ++++++++++
 .../chart/tool/test_update_chart_preview.py   |  6 ++-
 8 files changed, 121 insertions(+), 2 deletions(-)

diff --git a/superset/mcp_service/chart/chart_utils.py b/superset/mcp_service/chart/chart_utils.py
index d02e9aeb9ce0..c5eb72b121e4 100644
--- a/superset/mcp_service/chart/chart_utils.py
+++ b/superset/mcp_service/chart/chart_utils.py
@@ -567,6 +567,11 @@ 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
 
diff --git a/superset/mcp_service/chart/schemas.py b/superset/mcp_service/chart/schemas.py
index f58da9460880..c1fd8bc24ec0 100644
--- a/superset/mcp_service/chart/schemas.py
+++ b/superset/mcp_service/chart/schemas.py
@@ -1540,6 +1540,33 @@ 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)
+
+    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 +1613,18 @@ 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":
diff --git a/superset/mcp_service/chart/tool/update_chart.py b/superset/mcp_service/chart/tool/update_chart.py
index b18e8e10f8bc..121293d3cd30 100644
--- a/superset/mcp_service/chart/tool/update_chart.py
+++ b/superset/mcp_service/chart/tool/update_chart.py
@@ -117,6 +117,13 @@ def _build_update_payload(
             parsed_config, dataset_id=effective_dataset_id
         )
         new_form_data.pop("_mcp_warnings", None)
+        if getattr(parsed_config, "column_config", None) is None:
+            try:
+                existing_form_data = json.loads(chart.params) if chart.params else {}
+            except (ValueError, TypeError):
+                existing_form_data = {}
+            if existing_column_config := existing_form_data.get("column_config"):
+                new_form_data["column_config"] = existing_column_config
 
         chart_name = (
             request.chart_name
diff --git a/superset/mcp_service/chart/tool/update_chart_preview.py b/superset/mcp_service/chart/tool/update_chart_preview.py
index 78f11f066ad0..d394164bd735 100644
--- a/superset/mcp_service/chart/tool/update_chart_preview.py
+++ b/superset/mcp_service/chart/tool/update_chart_preview.py
@@ -186,6 +186,10 @@ 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 getattr(config, "column_config", None) is None and previous_form_data:
+                old_column_config = previous_form_data.get("column_config")
+                if old_column_config:
+                    new_form_data["column_config"] = old_column_config
 
             # Tier-1 schema validation against the dataset (no DB roundtrip).
             # Runs AFTER the filter merge so filter columns are also validated.
diff --git a/tests/unit_tests/mcp_service/chart/test_new_chart_types.py b/tests/unit_tests/mcp_service/chart/test_new_chart_types.py
index 48b1631568a9..8b7aa87cf7ad 100644
--- a/tests/unit_tests/mcp_service/chart/test_new_chart_types.py
+++ b/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."""
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py b/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py
index e90cbef3519d..1778f8c8ad9f 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py
@@ -44,10 +44,15 @@ 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
 
     def test_pie_schema_has_dimension_metric(self) -> None:
         result = _call_schema("pie")
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py b/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
index a4d1da7b2693..807fe2a7ad02 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
@@ -114,6 +114,26 @@ async def test_update_chart_with_chart_name(self):
         )
         assert request2.chart_name == "Updated Sales Report"
 
+    def test_unrelated_config_update_preserves_existing_column_config(self) -> None:
+        chart = Mock(
+            datasource_id=7,
+            params='{"column_config":{"Revenue":{"columnWidth":160}}}',
+            slice_name="Revenue table",
+        )
+        request = UpdateChartRequest(
+            identifier=123,
+            config=TableChartConfig(
+                chart_type="table",
+                columns=[ColumnRef(name="revenue", aggregate="SUM")],
+                row_limit=500,
+            ),
+        )
+
+        payload = _build_update_payload(request, chart, request.config)
+
+        assert isinstance(payload, dict)
+        assert '"column_config": {"Revenue": {"columnWidth": 160}}' in payload["params"]
+
     @pytest.mark.asyncio
     async def test_update_chart_preview_formats(self):
         """Test preview_formats options in update request."""
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py b/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
index fe5c88b9d91b..6e126dfe13e8 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
@@ -689,7 +689,8 @@ async def test_preserves_previous_adhoc_filters_without_warning(
             }
         ]
         mock_get_previous_form_data.return_value = {
-            "adhoc_filters": cached_adhoc_filters
+            "adhoc_filters": cached_adhoc_filters,
+            "column_config": {"Sales": {"d3NumberFormat": "$,.2f"}},
         }
         mock_generate_explore_link.return_value = (
             "http://localhost:8088/explore/?form_data_key=new_preview_key"
@@ -718,6 +719,9 @@ async def test_preserves_previous_adhoc_filters_without_warning(
 
         generated_form_data = mock_generate_explore_link.call_args.args[1]
         assert generated_form_data["adhoc_filters"] == cached_adhoc_filters
+        assert generated_form_data["column_config"] == {
+            "Sales": {"d3NumberFormat": "$,.2f"}
+        }
         assert result["success"] is True
         assert result["error"] is None
         assert result["warnings"] == []

From 2c31ba146de8a9818ca350d1a85dc811e9f20a54 Mon Sep 17 00:00:00 2001
From: Amin Ghadersohi <amin.ghadersohi@gmail.com>
Date: Tue, 4 Aug 2026 19:45:38 +0000
Subject: [PATCH 2/2] fix(mcp): preserve table column settings

---
 superset/mcp_service/chart/chart_utils.py     | 34 ++++++++
 superset/mcp_service/chart/schemas.py         |  6 +-
 .../mcp_service/chart/tool/update_chart.py    | 34 ++++----
 .../chart/tool/update_chart_preview.py        |  7 +-
 .../mcp_service/chart/test_chart_utils.py     | 38 +++++++++
 .../chart/tool/test_get_chart_type_schema.py  |  2 +
 .../chart/tool/test_update_chart.py           | 83 +++++++++++++++++++
 .../chart/tool/test_update_chart_preview.py   |  9 +-
 8 files changed, 190 insertions(+), 23 deletions(-)

diff --git a/superset/mcp_service/chart/chart_utils.py b/superset/mcp_service/chart/chart_utils.py
index c5eb72b121e4..cba958119980 100644
--- a/superset/mcp_service/chart/chart_utils.py
+++ b/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
 
@@ -576,6 +577,39 @@ def map_table_config(config: TableChartConfig) -> Dict[str, Any]:
     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.
 
diff --git a/superset/mcp_service/chart/schemas.py b/superset/mcp_service/chart/schemas.py
index c1fd8bc24ec0..27ebdaaed70c 100644
--- a/superset/mcp_service/chart/schemas.py
+++ b/superset/mcp_service/chart/schemas.py
@@ -1543,7 +1543,11 @@ def validate_metric_aggregate(self) -> Self:
 class TableColumnConfig(UnknownFieldCheckMixin):
     """Display formatting supported by the MCP table-chart schema."""
 
-    model_config = ConfigDict(extra="ignore", populate_by_name=True)
+    model_config = ConfigDict(
+        extra="ignore",
+        populate_by_name=True,
+        json_schema_extra={"additionalProperties": False},
+    )
 
     column_width: int | None = Field(
         None,
diff --git a/superset/mcp_service/chart/tool/update_chart.py b/superset/mcp_service/chart/tool/update_chart.py
index 121293d3cd30..c26e90d91347 100644
--- a/superset/mcp_service/chart/tool/update_chart.py
+++ b/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(
         {
@@ -117,13 +132,7 @@ def _build_update_payload(
             parsed_config, dataset_id=effective_dataset_id
         )
         new_form_data.pop("_mcp_warnings", None)
-        if getattr(parsed_config, "column_config", None) is None:
-            try:
-                existing_form_data = json.loads(chart.params) if chart.params else {}
-            except (ValueError, TypeError):
-                existing_form_data = {}
-            if existing_column_config := existing_form_data.get("column_config"):
-                new_form_data["column_config"] = existing_column_config
+        merge_table_column_config(_get_existing_form_data(chart), new_form_data)
 
         chart_name = (
             request.chart_name
@@ -171,15 +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
@@ -192,6 +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:
diff --git a/superset/mcp_service/chart/tool/update_chart_preview.py b/superset/mcp_service/chart/tool/update_chart_preview.py
index d394164bd735..08a6b6f03ffe 100644
--- a/superset/mcp_service/chart/tool/update_chart_preview.py
+++ b/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 (
@@ -186,10 +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 getattr(config, "column_config", None) is None and previous_form_data:
-                old_column_config = previous_form_data.get("column_config")
-                if old_column_config:
-                    new_form_data["column_config"] = old_column_config
+            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.
diff --git a/tests/unit_tests/mcp_service/chart/test_chart_utils.py b/tests/unit_tests/mcp_service/chart/test_chart_utils.py
index 256ee7032c43..314d9575f4a0 100644
--- a/tests/unit_tests/mcp_service/chart/test_chart_utils.py
+++ b/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"""
 
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py b/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py
index 1778f8c8ad9f..e1fbb27d0ae6 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_get_chart_type_schema.py
@@ -53,6 +53,8 @@ def test_table_schema_has_columns_and_column_config(self) -> None:
         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")
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py b/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
index 807fe2a7ad02..723ce42c4941 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_update_chart.py
@@ -43,6 +43,7 @@
     _build_preview_form_data,
     _build_update_payload,
 )
+from superset.utils import json
 
 # The __init__.py re-exports the update_chart *function*, so a plain
 # `from ... import update_chart` gives the function, not the module.
@@ -134,6 +135,51 @@ def test_unrelated_config_update_preserves_existing_column_config(self) -> None:
         assert isinstance(payload, dict)
         assert '"column_config": {"Revenue": {"columnWidth": 160}}' in payload["params"]
 
+    @pytest.mark.parametrize("params", ["null", "[]", '"text"', "1", "true"])
+    def test_config_update_treats_non_object_params_as_empty(self, params: str) -> None:
+        chart = Mock(datasource_id=7, params=params, slice_name="Revenue table", id=123)
+        request = UpdateChartRequest(
+            identifier=123,
+            config=TableChartConfig(
+                chart_type="table", columns=[ColumnRef(name="revenue")]
+            ),
+        )
+
+        payload = _build_update_payload(request, chart, request.config)
+
+        assert isinstance(payload, dict)
+        assert "column_config" not in json.loads(payload["params"])
+
+    def test_explicit_column_update_merges_saved_ui_settings(self) -> None:
+        chart = Mock(
+            datasource_id=7,
+            params=json.dumps(
+                {
+                    "column_config": {
+                        "Revenue": {"columnWidth": 80, "visible": False},
+                        "Region": {"customColumnName": "Sales region"},
+                    }
+                }
+            ),
+            slice_name="Revenue table",
+        )
+        config = TableChartConfig.model_validate(
+            {
+                "chart_type": "table",
+                "columns": [{"name": "revenue", "aggregate": "SUM"}],
+                "column_config": {"Revenue": {"columnWidth": 120}},
+            }
+        )
+        request = UpdateChartRequest(identifier=123, config=config)
+
+        payload = _build_update_payload(request, chart, config)
+
+        assert isinstance(payload, dict)
+        assert json.loads(payload["params"])["column_config"] == {
+            "Revenue": {"columnWidth": 120, "visible": False},
+            "Region": {"customColumnName": "Sales region"},
+        }
+
     @pytest.mark.asyncio
     async def test_update_chart_preview_formats(self):
         """Test preview_formats options in update request."""
@@ -905,6 +951,43 @@ def test_merges_existing_params_with_new_config(self):
         assert result["datasource"] == "7__table"
         assert result["slice_name"] == "Existing"
 
+    def test_partial_column_config_merges_saved_ui_settings(self) -> None:
+        config = TableChartConfig.model_validate(
+            {
+                "chart_type": "table",
+                "columns": [{"name": "revenue", "aggregate": "SUM"}],
+                "column_config": {
+                    "Revenue": {"columnWidth": 120, "d3NumberFormat": "$,.2f"}
+                },
+            }
+        )
+        request = UpdateChartRequest(identifier=1, config=config)
+        chart = Mock(
+            id=42,
+            datasource_id=7,
+            slice_name="Existing",
+            params=json.dumps(
+                {
+                    "column_config": {
+                        "Revenue": {"columnWidth": 80, "visible": False},
+                        "Region": {"customColumnName": "Sales region"},
+                    }
+                }
+            ),
+        )
+
+        result = _build_preview_form_data(request, chart, parsed_config=config)
+
+        assert isinstance(result, dict)
+        assert result["column_config"] == {
+            "Revenue": {
+                "columnWidth": 120,
+                "d3NumberFormat": "$,.2f",
+                "visible": False,
+            },
+            "Region": {"customColumnName": "Sales region"},
+        }
+
     def test_name_only_preview_keeps_existing_form_data(self):
         """Name-only preview preserves existing form_data and renames."""
         request = UpdateChartRequest(identifier=1, chart_name="Brand New Name")
diff --git a/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py b/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
index 6e126dfe13e8..b33100a07447 100644
--- a/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
+++ b/tests/unit_tests/mcp_service/chart/tool/test_update_chart_preview.py
@@ -690,7 +690,7 @@ async def test_preserves_previous_adhoc_filters_without_warning(
         ]
         mock_get_previous_form_data.return_value = {
             "adhoc_filters": cached_adhoc_filters,
-            "column_config": {"Sales": {"d3NumberFormat": "$,.2f"}},
+            "column_config": {"Sales": {"d3NumberFormat": "$,.2f", "visible": False}},
         }
         mock_generate_explore_link.return_value = (
             "http://localhost:8088/explore/?form_data_key=new_preview_key"
@@ -708,6 +708,7 @@ async def test_preserves_previous_adhoc_filters_without_warning(
                     ColumnRef(name="sales", label="Sales", aggregate="SUM"),
                 ],
                 sort_by=["sales"],
+                column_config={"Sales": {"columnWidth": 120}},
             ),
             generate_preview=True,
             preview_formats=["table"],
@@ -720,7 +721,11 @@ async def test_preserves_previous_adhoc_filters_without_warning(
         generated_form_data = mock_generate_explore_link.call_args.args[1]
         assert generated_form_data["adhoc_filters"] == cached_adhoc_filters
         assert generated_form_data["column_config"] == {
-            "Sales": {"d3NumberFormat": "$,.2f"}
+            "Sales": {
+                "columnWidth": 120,
+                "d3NumberFormat": "$,.2f",
+                "visible": False,
+            }
         }
         assert result["success"] is True
         assert result["error"] is None