diff --git a/docs/docs/configuration/theming.mdx b/docs/docs/configuration/theming.mdx
index 13ee29d39fe..e37d4eb0274 100644
--- a/docs/docs/configuration/theming.mdx
+++ b/docs/docs/configuration/theming.mdx
@@ -165,6 +165,206 @@ Or in the CRUD interface theme JSON:
 
 This feature works with the stock Docker image - no custom build required!
 
+## ECharts Configuration Overrides
+
+:::note
+Available since Superset 6.0
+:::
+
+Superset provides fine-grained control over ECharts visualizations through theme-level configuration overrides. This allows you to customize the appearance and behavior of all ECharts-based charts without modifying individual chart configurations.
+
+### Global ECharts Overrides
+
+Apply settings to all ECharts visualizations using `echartsOptionsOverrides`:
+
+```python
+THEME_DEFAULT = {
+    "token": {
+        "colorPrimary": "#2893B3",
+        # ... other Ant Design tokens
+    },
+    "echartsOptionsOverrides": {
+        "grid": {
+            "left": "10%",
+            "right": "10%",
+            "top": "15%",
+            "bottom": "15%"
+        },
+        "tooltip": {
+            "backgroundColor": "rgba(0, 0, 0, 0.8)",
+            "borderColor": "#ccc",
+            "textStyle": {
+                "color": "#fff"
+            }
+        },
+        "legend": {
+            "textStyle": {
+                "fontSize": 14,
+                "fontWeight": "bold"
+            }
+        }
+    }
+}
+```
+
+### Chart-Specific Overrides
+
+Target specific chart types using `echartsOptionsOverridesByChartType`:
+
+```python
+THEME_DEFAULT = {
+    "token": {
+        "colorPrimary": "#2893B3",
+        # ... other tokens
+    },
+    "echartsOptionsOverridesByChartType": {
+        "echarts_pie": {
+            "legend": {
+                "orient": "vertical",
+                "right": 10,
+                "top": "center"
+            }
+        },
+        "echarts_timeseries": {
+            "xAxis": {
+                "axisLabel": {
+                    "rotate": 45,
+                    "fontSize": 12
+                }
+            },
+            "dataZoom": [{
+                "type": "slider",
+                "show": True,
+                "start": 0,
+                "end": 100
+            }]
+        },
+        "echarts_bubble": {
+            "grid": {
+                "left": "15%",
+                "bottom": "20%"
+            }
+        }
+    }
+}
+```
+
+### UI Configuration
+
+You can also configure ECharts overrides through the theme CRUD interface:
+
+```json
+{
+  "token": {
+    "colorPrimary": "#2893B3"
+  },
+  "echartsOptionsOverrides": {
+    "grid": {
+      "left": "10%",
+      "right": "10%"
+    },
+    "tooltip": {
+      "backgroundColor": "rgba(0, 0, 0, 0.8)"
+    }
+  },
+  "echartsOptionsOverridesByChartType": {
+    "echarts_pie": {
+      "legend": {
+        "orient": "vertical",
+        "right": 10
+      }
+    }
+  }
+}
+```
+
+### Override Precedence
+
+The system applies overrides in the following order (last wins):
+
+1. **Base ECharts theme** - Default Superset styling
+2. **Plugin options** - Chart-specific configurations
+3. **Global overrides** - `echartsOptionsOverrides`
+4. **Chart-specific overrides** - `echartsOptionsOverridesByChartType[chartType]`
+
+This ensures chart-specific overrides take precedence over global ones.
+
+### Common Chart Types
+
+Available chart types for `echartsOptionsOverridesByChartType`:
+
+- `echarts_timeseries` - Time series/line charts
+- `echarts_pie` - Pie and donut charts
+- `echarts_bubble` - Bubble/scatter charts
+- `echarts_funnel` - Funnel charts
+- `echarts_gauge` - Gauge charts
+- `echarts_radar` - Radar charts
+- `echarts_boxplot` - Box plot charts
+- `echarts_treemap` - Treemap charts
+- `echarts_sunburst` - Sunburst charts
+- `echarts_graph` - Network/graph charts
+- `echarts_sankey` - Sankey diagrams
+- `echarts_heatmap` - Heatmaps
+- `echarts_mixed_timeseries` - Mixed time series
+
+### Best Practices
+
+1. **Start with global overrides** for consistent styling across all charts
+2. **Use chart-specific overrides** for unique requirements per visualization type
+3. **Test thoroughly** as overrides use deep merge - nested objects are combined, but arrays are completely replaced
+4. **Document your overrides** to help team members understand custom styling
+5. **Consider performance** - complex overrides may impact chart rendering speed
+
+### Example: Corporate Branding
+
+```python
+# Complete corporate theme with ECharts customization
+THEME_DEFAULT = {
+    "token": {
+        "colorPrimary": "#1B4D3E",
+        "fontFamily": "Corporate Sans, Arial, sans-serif"
+    },
+    "echartsOptionsOverrides": {
+        "grid": {
+            "left": "8%",
+            "right": "8%",
+            "top": "12%",
+            "bottom": "12%"
+        },
+        "textStyle": {
+            "fontFamily": "Corporate Sans, Arial, sans-serif"
+        },
+        "title": {
+            "textStyle": {
+                "color": "#1B4D3E",
+                "fontSize": 18,
+                "fontWeight": "bold"
+            }
+        }
+    },
+    "echartsOptionsOverridesByChartType": {
+        "echarts_timeseries": {
+            "xAxis": {
+                "axisLabel": {
+                    "color": "#666",
+                    "fontSize": 11
+                }
+            }
+        },
+        "echarts_pie": {
+            "legend": {
+                "textStyle": {
+                    "fontSize": 12
+                },
+                "itemGap": 20
+            }
+        }
+    }
+}
+```
+
+This feature provides powerful theming capabilities while maintaining the flexibility of ECharts' extensive configuration options.
+
 ## Advanced Features
 
 - **System Themes**: Manage system-wide default and dark themes via UI or configuration
diff --git a/superset-frontend/packages/superset-ui-core/src/theme/types.ts b/superset-frontend/packages/superset-ui-core/src/theme/types.ts
index a391e80037d..b9e2a000ea3 100644
--- a/superset-frontend/packages/superset-ui-core/src/theme/types.ts
+++ b/superset-frontend/packages/superset-ui-core/src/theme/types.ts
@@ -127,6 +127,15 @@ export interface SupersetSpecificTokens {
   // Spinner-related
   brandSpinnerUrl?: string;
   brandSpinnerSvg?: string;
+
+  // ECharts-related
+  /** Global ECharts configuration overrides applied to all chart types */
+  echartsOptionsOverrides?: any;
+
+  /** Chart-specific ECharts configuration overrides keyed by viz_type */
+  echartsOptionsOverridesByChartType?: {
+    [chartType: string]: any;
+  };
 }
 
 /**
diff --git a/superset-frontend/packages/superset-ui-core/src/utils/index.ts b/superset-frontend/packages/superset-ui-core/src/utils/index.ts
index aebddc5459a..bb099c9bf82 100644
--- a/superset-frontend/packages/superset-ui-core/src/utils/index.ts
+++ b/superset-frontend/packages/superset-ui-core/src/utils/index.ts
@@ -33,3 +33,4 @@ export * from './random';
 export * from './typedMemo';
 export * from './html';
 export * from './tooltip';
+export * from './merge';
diff --git a/superset-frontend/packages/superset-ui-core/src/utils/merge.test.ts b/superset-frontend/packages/superset-ui-core/src/utils/merge.test.ts
new file mode 100644
index 00000000000..73a27f53648
--- /dev/null
+++ b/superset-frontend/packages/superset-ui-core/src/utils/merge.test.ts
@@ -0,0 +1,61 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { mergeReplaceArrays } from './merge';
+
+describe('lodash utilities', () => {
+  describe('mergeReplaceArrays', () => {
+    it('should merge objects and replace arrays', () => {
+      const obj1 = { a: [1, 2], b: { c: 3 } };
+      const obj2 = { a: [4, 5], b: { d: 6 } };
+
+      const result = mergeReplaceArrays(obj1, obj2);
+
+      expect(result).toEqual({
+        a: [4, 5], // array replaced
+        b: { c: 3, d: 6 }, // objects merged
+      });
+    });
+
+    it('should handle precedence with multiple sources', () => {
+      const base = { x: { y: 1 }, z: [1] };
+      const override1 = { x: { y: 2 }, z: [2, 3] };
+      const override2 = { x: { y: 3 }, z: [4] };
+
+      const result = mergeReplaceArrays(base, override1, override2);
+
+      expect(result).toEqual({
+        x: { y: 3 }, // last wins
+        z: [4], // array replaced by last
+      });
+    });
+
+    it('should handle empty and null values', () => {
+      const base = { a: [1], b: { x: 1 } };
+      const override = { a: [], b: { x: null } };
+
+      const result = mergeReplaceArrays(base, override);
+
+      expect(result).toEqual({
+        a: [], // empty array replaces
+        b: { x: null }, // null overrides
+      });
+    });
+  });
+});
diff --git a/superset-frontend/packages/superset-ui-core/src/utils/merge.ts b/superset-frontend/packages/superset-ui-core/src/utils/merge.ts
new file mode 100644
index 00000000000..bde3783f908
--- /dev/null
+++ b/superset-frontend/packages/superset-ui-core/src/utils/merge.ts
@@ -0,0 +1,52 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import { mergeWith } from 'lodash';
+
+/**
+ * Merges objects using lodash.mergeWith, but replaces arrays instead of concatenating them.
+ * This is useful for configuration objects where you want to completely override array values
+ * rather than merge them by index.
+ *
+ * @example
+ * const obj1 = { a: [1, 2], b: { c: 3 } };
+ * const obj2 = { a: [4, 5], b: { d: 6 } };
+ * mergeReplaceArrays(obj1, obj2);
+ * // Result: { a: [4, 5], b: { c: 3, d: 6 } }
+ *
+ * @example
+ * // ECharts configuration merging
+ * const baseConfig = { series: [{ type: 'line' }], grid: { left: '10%' } };
+ * const overrides = { series: [{ type: 'bar' }], grid: { right: '10%' } };
+ * mergeReplaceArrays(baseConfig, overrides);
+ * // Result: { series: [{ type: 'bar' }], grid: { left: '10%', right: '10%' } }
+ *
+ * @param sources - Objects to merge (rightmost wins for arrays, deep merge for objects)
+ * @returns Merged object with arrays replaced, not concatenated
+ */
+export function mergeReplaceArrays<T = any>(...sources: any[]): T {
+  const replaceArrays = (objValue: any, srcValue: any) => {
+    if (Array.isArray(srcValue)) {
+      return srcValue; // Replace arrays entirely
+    }
+    return undefined; // Let lodash handle object merging for non-arrays
+  };
+
+  return mergeWith({}, ...sources, replaceArrays);
+}
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/Bubble/EchartsBubble.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/Bubble/EchartsBubble.tsx
index 4aab4a2d240..adfa0acfe30 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/Bubble/EchartsBubble.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/Bubble/EchartsBubble.tsx
@@ -20,13 +20,14 @@ import { BubbleChartTransformedProps } from './types';
 import Echart from '../components/Echart';
 
 export default function EchartsBubble(props: BubbleChartTransformedProps) {
-  const { height, width, echartOptions, refs } = props;
+  const { height, width, echartOptions, refs, formData } = props;
   return (
     <Echart
       height={height}
       width={width}
       echartOptions={echartOptions}
       refs={refs}
+      vizType={formData.vizType}
     />
   );
 }
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/Funnel/EchartsFunnel.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/Funnel/EchartsFunnel.tsx
index 4ae0ab49209..c3b2c81a12a 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/Funnel/EchartsFunnel.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/Funnel/EchartsFunnel.tsx
@@ -21,7 +21,8 @@ import Echart from '../components/Echart';
 import { allEventHandlers } from '../utils/eventHandlers';
 
 export default function EchartsFunnel(props: FunnelChartTransformedProps) {
-  const { height, width, echartOptions, selectedValues, refs } = props;
+  const { height, width, echartOptions, selectedValues, refs, formData } =
+    props;
 
   const eventHandlers = allEventHandlers(props);
 
@@ -33,6 +34,7 @@ export default function EchartsFunnel(props: FunnelChartTransformedProps) {
       echartOptions={echartOptions}
       eventHandlers={eventHandlers}
       selectedValues={selectedValues}
+      vizType={formData.vizType}
     />
   );
 }
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/Gauge/EchartsGauge.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/Gauge/EchartsGauge.tsx
index 14ec2ebb7c8..3482977f83e 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/Gauge/EchartsGauge.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/Gauge/EchartsGauge.tsx
@@ -21,7 +21,8 @@ import Echart from '../components/Echart';
 import { allEventHandlers } from '../utils/eventHandlers';
 
 export default function EchartsGauge(props: GaugeChartTransformedProps) {
-  const { height, width, echartOptions, selectedValues, refs } = props;
+  const { height, width, echartOptions, selectedValues, refs, formData } =
+    props;
 
   const eventHandlers = allEventHandlers(props);
 
@@ -33,6 +34,7 @@ export default function EchartsGauge(props: GaugeChartTransformedProps) {
       echartOptions={echartOptions}
       eventHandlers={eventHandlers}
       selectedValues={selectedValues}
+      vizType={formData.vizType}
     />
   );
 }
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/Pie/EchartsPie.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/Pie/EchartsPie.tsx
index fb82cd53bcd..3f4d4f27747 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/Pie/EchartsPie.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/Pie/EchartsPie.tsx
@@ -21,7 +21,8 @@ import Echart from '../components/Echart';
 import { allEventHandlers } from '../utils/eventHandlers';
 
 export default function EchartsPie(props: PieChartTransformedProps) {
-  const { height, width, echartOptions, selectedValues, refs } = props;
+  const { height, width, echartOptions, selectedValues, refs, formData } =
+    props;
 
   const eventHandlers = allEventHandlers(props);
 
@@ -33,6 +34,7 @@ export default function EchartsPie(props: PieChartTransformedProps) {
       echartOptions={echartOptions}
       eventHandlers={eventHandlers}
       selectedValues={selectedValues}
+      vizType={formData.vizType}
     />
   );
 }
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/Radar/EchartsRadar.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/Radar/EchartsRadar.tsx
index b8937bd42d1..e97b06000e6 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/Radar/EchartsRadar.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/Radar/EchartsRadar.tsx
@@ -21,7 +21,8 @@ import Echart from '../components/Echart';
 import { allEventHandlers } from '../utils/eventHandlers';
 
 export default function EchartsRadar(props: RadarChartTransformedProps) {
-  const { height, width, echartOptions, selectedValues, refs } = props;
+  const { height, width, echartOptions, selectedValues, refs, formData } =
+    props;
   const eventHandlers = allEventHandlers(props);
 
   return (
@@ -32,6 +33,7 @@ export default function EchartsRadar(props: RadarChartTransformedProps) {
       echartOptions={echartOptions}
       eventHandlers={eventHandlers}
       selectedValues={selectedValues}
+      vizType={formData.vizType}
     />
   );
 }
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/Timeseries/EchartsTimeseries.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/Timeseries/EchartsTimeseries.tsx
index 79bec925a85..03bf68fd2aa 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/Timeseries/EchartsTimeseries.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/Timeseries/EchartsTimeseries.tsx
@@ -282,6 +282,7 @@ export default function EchartsTimeseries({
         eventHandlers={eventHandlers}
         zrEventHandlers={zrEventHandlers}
         selectedValues={selectedValues}
+        vizType={formData.vizType}
       />
     </>
   );
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/components/Echart.tsx b/superset-frontend/plugins/plugin-chart-echarts/src/components/Echart.tsx
index 77f03521fcf..c4211468809 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/components/Echart.tsx
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/components/Echart.tsx
@@ -27,11 +27,9 @@ import {
   Ref,
   useState,
 } from 'react';
-import { merge } from 'lodash';
-
 import { useSelector } from 'react-redux';
 
-import { styled, useTheme } from '@superset-ui/core';
+import { styled, useTheme, mergeReplaceArrays } from '@superset-ui/core';
 import { use, init, EChartsType, registerLocale } from 'echarts/core';
 import {
   SankeyChart,
@@ -131,6 +129,7 @@ function Echart(
     zrEventHandlers,
     selectedValues = {},
     refs,
+    vizType,
   }: EchartsProps,
   ref: Ref<EchartsHandler>,
 ) {
@@ -237,11 +236,19 @@ function Echart(
         return echartsTheme;
       };
 
-      const themedEchartOptions = merge(
-        {},
-        getEchartsTheme(echartOptions),
+      const baseTheme = getEchartsTheme(echartOptions);
+      const globalOverrides = theme.echartsOptionsOverrides || {};
+      const chartOverrides = vizType
+        ? theme.echartsOptionsOverridesByChartType?.[vizType] || {}
+        : {};
+
+      const themedEchartOptions = mergeReplaceArrays(
+        baseTheme,
         echartOptions,
+        globalOverrides,
+        chartOverrides,
       );
+
       chartRef.current?.setOption(themedEchartOptions, true);
     }
   }, [didMount, echartOptions, eventHandlers, zrEventHandlers, theme]);
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/types.ts b/superset-frontend/plugins/plugin-chart-echarts/src/types.ts
index c8da425f65c..817996b3182 100644
--- a/superset-frontend/plugins/plugin-chart-echarts/src/types.ts
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/types.ts
@@ -55,6 +55,7 @@ export interface EchartsProps {
   selectedValues?: Record<number, string>;
   forceClear?: boolean;
   refs: Refs;
+  vizType?: string;
 }
 
 export interface EchartsHandler {
diff --git a/superset-frontend/plugins/plugin-chart-echarts/src/utils/themeOverrides.test.ts b/superset-frontend/plugins/plugin-chart-echarts/src/utils/themeOverrides.test.ts
new file mode 100644
index 00000000000..931f026cb5f
--- /dev/null
+++ b/superset-frontend/plugins/plugin-chart-echarts/src/utils/themeOverrides.test.ts
@@ -0,0 +1,263 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+import { mergeReplaceArrays } from '@superset-ui/core';
+
+describe('Theme Override Deep Merge Behavior', () => {
+  test('should merge nested objects correctly', () => {
+    const baseOptions = {
+      grid: {
+        left: '5%',
+        right: '5%',
+        top: '10%',
+      },
+      xAxis: {
+        type: 'category',
+        axisLabel: {
+          fontSize: 12,
+        },
+      },
+    };
+
+    const globalOverrides = {
+      grid: {
+        left: '10%',
+        bottom: '15%',
+      },
+      xAxis: {
+        axisLabel: {
+          color: '#333',
+          rotate: 45,
+        },
+      },
+    };
+
+    const result = mergeReplaceArrays(baseOptions, globalOverrides);
+
+    expect(result).toEqual({
+      grid: {
+        left: '10%', // overridden
+        right: '5%', // preserved
+        top: '10%', // preserved
+        bottom: '15%', // added
+      },
+      xAxis: {
+        type: 'category', // preserved
+        axisLabel: {
+          fontSize: 12, // preserved
+          color: '#333', // added
+          rotate: 45, // added
+        },
+      },
+    });
+  });
+
+  test('should replace arrays instead of merging them', () => {
+    const baseOptions = {
+      series: [
+        { name: 'Series 1', type: 'line' },
+        { name: 'Series 2', type: 'bar' },
+      ],
+    };
+
+    const overrides = {
+      series: [{ name: 'New Series', type: 'pie' }],
+    };
+
+    const result = mergeReplaceArrays(baseOptions, overrides);
+
+    // Arrays are replaced entirely, not merged by index
+    expect(result.series).toEqual([{ name: 'New Series', type: 'pie' }]);
+    expect(result.series).toHaveLength(1);
+  });
+
+  test('should handle null overrides correctly', () => {
+    const baseOptions = {
+      grid: {
+        left: '5%',
+        right: '5%',
+        top: '10%',
+      },
+      tooltip: {
+        show: true,
+        backgroundColor: '#fff',
+      },
+    };
+
+    const overrides = {
+      grid: {
+        left: null,
+        bottom: '20%',
+      },
+      tooltip: {
+        backgroundColor: null,
+        borderColor: '#ccc',
+      },
+    };
+
+    const result = mergeReplaceArrays(baseOptions, overrides);
+
+    expect(result).toEqual({
+      grid: {
+        left: null, // overridden with null
+        right: '5%', // preserved (undefined values are ignored by lodash merge)
+        top: '10%', // preserved
+        bottom: '20%', // added
+      },
+      tooltip: {
+        show: true, // preserved
+        backgroundColor: null, // overridden with null
+        borderColor: '#ccc', // added
+      },
+    });
+  });
+
+  test('should handle override precedence correctly', () => {
+    const baseTheme = {
+      textStyle: { color: '#000', fontSize: 12 },
+    };
+
+    const pluginOptions = {
+      textStyle: { fontSize: 14 },
+      title: { text: 'Chart Title' },
+    };
+
+    const globalOverrides = {
+      textStyle: { color: '#333' },
+      grid: { left: '10%' },
+    };
+
+    const chartOverrides = {
+      textStyle: { color: '#666', fontWeight: 'bold' },
+      legend: { orient: 'vertical' },
+    };
+
+    // Simulate the merge order in Echart.tsx
+    const result = mergeReplaceArrays(
+      baseTheme,
+      pluginOptions,
+      globalOverrides,
+      chartOverrides,
+    );
+
+    expect(result).toEqual({
+      textStyle: {
+        color: '#666', // chart override wins
+        fontSize: 14, // from plugin options
+        fontWeight: 'bold', // from chart override
+      },
+      title: { text: 'Chart Title' }, // from plugin options
+      grid: { left: '10%' }, // from global override
+      legend: { orient: 'vertical' }, // from chart override
+    });
+  });
+
+  test('should preserve deep nested structures', () => {
+    const baseOptions = {
+      xAxis: {
+        axisLabel: {
+          textStyle: {
+            color: '#000',
+            fontSize: 12,
+            fontFamily: 'Arial',
+          },
+        },
+      },
+    };
+
+    const overrides = {
+      xAxis: {
+        axisLabel: {
+          textStyle: {
+            color: '#333',
+            fontWeight: 'bold',
+          },
+          rotate: 45,
+        },
+        splitLine: {
+          show: true,
+        },
+      },
+    };
+
+    const result = mergeReplaceArrays(baseOptions, overrides);
+
+    expect(result).toEqual({
+      xAxis: {
+        axisLabel: {
+          textStyle: {
+            color: '#333', // overridden
+            fontSize: 12, // preserved
+            fontFamily: 'Arial', // preserved
+            fontWeight: 'bold', // added
+          },
+          rotate: 45, // added
+        },
+        splitLine: {
+          show: true, // added
+        },
+      },
+    });
+  });
+
+  test('should handle function values correctly', () => {
+    const formatFunction = (value: any) => `${value}%`;
+    const overrideFunction = (value: any) => `$${value}`;
+
+    const baseOptions = {
+      yAxis: {
+        axisLabel: {
+          formatter: formatFunction,
+        },
+      },
+    };
+
+    const overrides = {
+      yAxis: {
+        axisLabel: {
+          formatter: overrideFunction,
+        },
+      },
+    };
+
+    const result = mergeReplaceArrays(baseOptions, overrides);
+
+    expect(result.yAxis.axisLabel.formatter).toBe(overrideFunction);
+    expect(result.yAxis.axisLabel.formatter('100')).toBe('$100');
+  });
+
+  test('should handle empty objects and arrays', () => {
+    const baseOptions = {
+      series: [{ name: 'Test', data: [1, 2, 3] }],
+      grid: { left: '5%' },
+    };
+
+    const emptyOverrides = {};
+    const arrayOverride = { series: [] };
+    const objectOverride = { grid: {} };
+
+    const resultEmpty = mergeReplaceArrays(baseOptions, emptyOverrides);
+    const resultArray = mergeReplaceArrays(baseOptions, arrayOverride);
+    const resultObject = mergeReplaceArrays(baseOptions, objectOverride);
+
+    expect(resultEmpty).toEqual(baseOptions);
+    // Empty array completely replaces existing array
+    expect(resultArray.series).toEqual([]);
+    expect(resultObject.grid).toEqual({ left: '5%' });
+  });
+});
diff --git a/superset-frontend/scripts/build.js b/superset-frontend/scripts/build.js
old mode 100644
new mode 100755