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web/src/pages/admin/table_definition/state.rs

@@ -85,6 +85,7 @@ impl TableSummary {
 pub(crate) struct TableDetailView {
     pub id: i64,
     pub row_version: i64,
+    pub has_data: bool,
     pub row_display_columns: Vec<String>,
     pub columns: Vec<DetailColumn>,
     pub scripts: Vec<ScriptView>,
@@ -377,6 +378,12 @@ pub(crate) struct TableDefinitionPageState {
 }
 
 impl TableDefinitionPageState {
+    /// Empty dynamic tables may be reshaped atomically. Once data exists, the
+    /// backend deliberately exposes only append-only column changes.
+    pub(crate) fn can_adjust_definition(&self) -> bool {
+        self.table_is_writable() && self.detail.as_ref().is_some_and(|detail| !detail.has_data)
+    }
+
     pub(crate) fn column_is_selected_for_removal(&self, column_id: &i64) -> bool {
         self.remove_column_ids.contains(column_id)
     }
@@ -486,6 +493,7 @@ mod tests {
         let detail = TableDetailView {
             id: 1,
             row_version: 1,
+            has_data: false,
             row_display_columns: Vec::new(),
             scripts: Vec::new(),
             columns: vec![