refering different tables that are not directly FK

common/proto/table_script.proto

@@ -70,6 +70,12 @@ message PostTableScriptRequest {
   //       • current-table references are read directly from the active row
   //       • other tables require an explicit link from the source table
   //         (table_definition_links) or the request fails
+  //   - Related collections use allowlisted aggregate shorthand:
+  //       @sum(table.column), @min(table.column), @max(table.column),
+  //       @count(table.column), @count_distinct(table.column),
+  //       @any(table.boolean), @all(table.boolean),
+  //       @count_rows(table), @exists(table)
+  //       The related table must be a direct child or share exactly one parent.
   //   - Raw SQL access is not supported; steel_query_sql is rejected
   //
   // Math operations:
@@ -130,4 +136,7 @@ message ScriptDependency {
   string column = 3;
   // Deprecated legacy field. Raw SQL dependencies are no longer produced.
   string query_fragment = 4;
+  string operation = 5;
+  // Relationship table used to match the owner row to the related collection.
+  string via_table = 6;
 }