cant change logic once data are in that column

common/proto/table_definition.proto

@@ -14,6 +14,10 @@ service TableDefinition {
   // Also inserts metadata and default validation rules. Entirely transactional.
   rpc PostTableDefinition(PostTableDefinitionRequest) returns (TableDefinitionResponse);
 
+  // Appends new user-defined columns to an existing table.
+  // Existing columns, links, and table logic are never changed by this call.
+  rpc AddTableColumns(AddTableColumnsRequest) returns (TableDefinitionResponse);
+
   // Lists all profiles (schemas) and their tables with declared dependencies.
   // This provides a tree-like overview of table relationships.
   rpc GetProfileTree(komp_ac.common.Empty) returns (ProfileTreeResponse);
@@ -72,6 +76,21 @@ message PostTableDefinitionRequest {
   string profile_name = 5;
 }
 
+// Defines append-only column additions for an existing table.
+message AddTableColumnsRequest {
+  // Existing profile/schema name.
+  string profile_name = 1;
+
+  // Existing table name in the profile.
+  string table_name = 2;
+
+  // New user-defined columns only. Existing columns cannot be changed here.
+  repeated ColumnDefinition columns = 3;
+
+  // Optional indexes for the new columns only.
+  repeated string indexes = 4;
+}
+
 // Describes one user-defined column for a table.
 message ColumnDefinition {
   // Column name that follows the same validation rules as table_name.