postgres - two roles working on the same objects - postgresql

Question

I have a DB with many objects. All are owned by a role called app. This role is currently used by everyone and everything (manual users, rollout scripts, app itself ...).
The goal now is to have a shorter idle_in_transaction_session_timeout for manual users than for the rollout scripts.
I was told that creating a new role for manual users is the way to go. For simplicity, let's say there is only one manual user frank.
The goal would be that frank can create/alter/drop every object he or app created/owns and that app can create/alter/drop every object he or frank created/owns.
This seems difficult in postgres due to the way it works (creator = owner, only owner can alter/drop etc...).
Searching the internet for a solution only brings partial and quite complicated solutions such as event trigger on create table or not forgetting to issue set role always.
What is the best practice here?
*** Update: one suggestion below is to grant app to frank, but that does not do the trick. It causes the scenario that app can not modify objects created by frank:
CREATE ROLE "app" LOGIN;
CREATE ROLE "frank" LOGIN;
GRANT "app" TO "frank";
set role app;
create table created_by_app (id int);
set role frank;
create table created_by_frank (id int);
drop table created_by_app; -- works
set role app;
drop table created_by_frank; -- does not work
-- SQL Error [42501]: ERROR: must be owner of table created_by_frank

Answer 1

Use a single owner, like the "app" role, and let other inherit this role. Something like this:
CREATE ROLE "app" LOGIN;
CREATE ROLE "frank" LOGIN;
GRANT "app" TO "frank";
When "app" is the owner of a table, "frank" can still make changes to this table or even drop this table.
An event trigger could solve the issue that user might forget to set the ownership of a table. The function and the trigger could be something like this:
CREATE OR REPLACE FUNCTION tr_set_table_owner()
RETURNS event_trigger
LANGUAGE plpgsql
AS
$$
DECLARE
_table_name TEXT;
_schema_name TEXT;
_ddl_owner TEXT;
BEGIN
SELECT
objid::regclass
, schema_name
FROM pg_event_trigger_ddl_commands()
WHERE object_type = 'table'
AND command_tag = 'CREATE TABLE'
INTO _table_name, _schema_name;
IF FOUND THEN
_ddl_owner := format('ALTER TABLE %I.%I OWNER TO app;', _schema_name, _table_name);
RAISE NOTICE 'DDL: %', _ddl_owner;
EXECUTE _ddl_owner;
END IF;
END;
$$;
CREATE EVENT TRIGGER name
ON ddl_command_end
EXECUTE FUNCTION tr_set_table_owner();
Any new table created in your database, should now be assigned to the role "app". If you want this for other objects as well, just change the code in the trigger function.