diff --git a/src/types/charts.ts b/src/types/charts.ts
new file mode 100644
index 0000000..da057d5
--- /dev/null
+++ b/src/types/charts.ts
@@ -0,0 +1,12 @@
+/**
+ * Chart types for chart metadata.
+ *
+ * created_at is stored as a PostgreSQL timestamp (returned as Date by Drizzle ORM)
+ * but is often treated as a Unix epoch number in the frontend after JSON serialisation.
+ */
+
+export interface Chart {
+  id: number;
+  name: string;
+  created_at: Date | number;
+}