feat: auto-bind chart fields based on dataset columns

When creating a chart, automatically assign first text column to X axis
and first number column to Y axis (varies by chart type).
Charts now show data immediately instead of blank.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/frameworks/hooks/useCreateChart.ts

@@ -7,6 +7,7 @@ import { addChart, setActiveChart } from '@/adapters/state/redux/chartSlice';
 import { addLayoutItem } from '@/adapters/state/redux/layoutSlice';
 import { type ChartType } from '@/domain';
 import { type ChartInstance } from '@/domain/entities/ChartInstance';
+import { type FieldBinding } from '@/domain/entities/FieldBinding';
 
 function mapBackendChart(raw: any): ChartInstance {
   return {
@@ -31,9 +32,58 @@ function mapBackendChart(raw: any): ChartInstance {
   };
 }
 
+/**
+ * Auto-generate default bindings based on chart type and available columns.
+ */
+function autoBindings(
+  chartType: string,
+  columns: { name: string; type: string }[],
+): FieldBinding[] {
+  const textCols = columns.filter((c) => c.type === 'text' || c.type === 'geo');
+  const numCols = columns.filter((c) => c.type === 'number' || c.type === 'percentage');
+  const dateCols = columns.filter((c) => c.type === 'date');
+
+  const bindings: FieldBinding[] = [];
+
+  switch (chartType) {
+    case 'pie':
+    case 'donut':
+    case 'wordcloud':
+    case 'radar':
+      if (textCols[0]) bindings.push({ axis: 'label', columnName: textCols[0].name });
+      if (numCols[0]) bindings.push({ axis: 'value', columnName: numCols[0].name });
+      break;
+    case 'map':
+      const geoCols = columns.filter((c) => c.type === 'geo');
+      if (geoCols[0]) bindings.push({ axis: 'geo', columnName: geoCols[0].name });
+      else if (textCols[0]) bindings.push({ axis: 'geo', columnName: textCols[0].name });
+      if (numCols[0]) bindings.push({ axis: 'value', columnName: numCols[0].name });
+      break;
+    case 'kpi':
+      if (numCols[0]) bindings.push({ axis: 'value', columnName: numCols[0].name });
+      if (textCols[0]) bindings.push({ axis: 'label', columnName: textCols[0].name });
+      break;
+    case 'scatter':
+    case 'boston-matrix':
+      if (numCols[0]) bindings.push({ axis: 'x', columnName: numCols[0].name });
+      if (numCols[1]) bindings.push({ axis: 'y', columnName: numCols[1].name });
+      break;
+    default: // bar, line, area, grouped-bar, stacked-bar, horizontal-bar, combo, heatmap, data-table
+      if (dateCols[0]) bindings.push({ axis: 'x', columnName: dateCols[0].name });
+      else if (textCols[0]) bindings.push({ axis: 'x', columnName: textCols[0].name });
+      if (numCols[0]) bindings.push({ axis: 'y', columnName: numCols[0].name });
+      break;
+  }
+
+  return bindings;
+}
+
 export function useCreateChart() {
   const dispatch = useAppDispatch();
   const activeDataSetId = useAppSelector((s) => s.data.activeDataSetId);
+  const activeDataSet = useAppSelector((s) =>
+    s.data.dataSets.find((ds) => ds.id === s.data.activeDataSetId),
+  );
   const layoutCount = useAppSelector((s) => s.layout.layouts.length);
   const [loading, setLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
@@ -48,12 +98,27 @@ export function useCreateChart() {
       setLoading(true);
       setError(null);
       try {
+        // Auto-generate bindings from dataset columns
+        const columns = (activeDataSet?.columns ?? []).map((c) => ({
+          name: c.name,
+          type: c.type,
+        }));
+        const defaultBindings = autoBindings(chartType ?? 'bar', columns);
+
         const rawChart = await chartServiceClient.createChart(
           activeDataSetId,
           chartType ?? 'bar',
+          defaultBindings.map((b) => ({
+            axis: b.axis,
+            column_name: b.columnName,
+            aggregation: b.aggregation ?? null,
+          })),
         );
         const chart = mapBackendChart(rawChart);
 
+        // Override bindings with our auto-generated ones (backend may not have them)
+        chart.bindings = defaultBindings;
+
         dispatch(addChart(chart));
         dispatch(setActiveChart(chart.id));
 
@@ -76,7 +141,7 @@ export function useCreateChart() {
         setLoading(false);
       }
     },
-    [dispatch, activeDataSetId, layoutCount],
+    [dispatch, activeDataSetId, activeDataSet, layoutCount],
   );
 
   return { handleCreate, activeDataSetId, loading, error };