diff --git a/app/MindWork AI Studio/Chat/ChartDefinition.cs b/app/MindWork AI Studio/Chat/ChartDefinition.cs
new file mode 100644
index 00000000..8598f9fa
--- /dev/null
+++ b/app/MindWork AI Studio/Chat/ChartDefinition.cs	
@@ -0,0 +1,29 @@
+namespace AIStudio.Chat;
+
+/// <summary>
+/// A renderer-independent, validated chart definition produced by an AI response.
+/// </summary>
+public sealed record ChartDefinition(
+    int SchemaVersion,
+    ChartDefinitionType Type,
+    string Title,
+    string? Caption,
+    IReadOnlyList<string> Categories,
+    IReadOnlyList<ChartDefinitionSeries> Series);
+
+/// <summary>
+/// A named series in a chart definition.
+/// </summary>
+public sealed record ChartDefinitionSeries(string Name, IReadOnlyList<double> Values);
+
+/// <summary>
+/// Chart types supported by version 1 of the AI Studio chart contract.
+/// </summary>
+public enum ChartDefinitionType
+{
+    BAR,
+    STACKED_BAR,
+    LINE,
+    PIE,
+    DONUT,
+}