This is a request for two mutations:
add_to_column_value and remove_from_column_value
This would be used for people, dropdown, and tags columns, it would take a normal array of values and add them or remove them from the existing column value.
This isn’t just a shorthand - this is needed to resolve potential race conditions with the API.
To change these three column values, you must write the existing column value with or without the add or removed entities. This requires getting the existing value, and modifying the array and then changing the column with the new value.
Because of the way integrations/automations work, there is a possibility for several different recipes that do not have any awareness of each other (entirely different devs) to be acting simultaneously. Both get the current value and manipulate it, then write their new values - one succeeds, and then is immediately replaced by the other.
This could also be used for board_relation and dependency however these columns have different considerations (since linked items are now first order properties of items - and the columns just act as filters to expose only those connections associated with the column).