New accounts should be set to default when none exist for that currency

[gudnuf]

When a user adds an account for a currency that does not have any other accounts, the new account does not get set as default.

For example, if the user has no USD accounts and adds https://mint.lnvoltz.com for USD, the account gets added successfully, but they still have no default USD account. This is because of the change we made in #699 that makes a default usd account optional, and I didn't handle this case.

We could address this at the database level with a trigger function that sets the default_usd_account_id to the new account ID if no USD accounts exist for that user. The downside of this is that if we add more currencies, then we have to make new triggers (unless we changed our default currency schema to be more general).

To solve this problem, what do you think @jbojcic1 about a trigger that looks something like:

-- Create a trigger function that updates default_usd_account_id
create or replace function wallet.set_default_usd_account_on_insert()
returns trigger
language plpgsql
as $$
begin
  -- If this is a USD account and the user doesn't have a default USD account yet
  if NEW.currency = 'USD' then
    update wallet.users
    set default_usd_account_id = NEW.id
    where id = NEW.user_id
      and default_usd_account_id is null;
  end if;
  
  return NEW;
end;
$$;

-- Create the trigger
create trigger set_default_usd_account_trigger
after insert on wallet.accounts
for each row
execute function wallet.set_default_usd_account_on_insert();

Otherwise, I think we would need to make an add_account database function with a make_default: bool param that we call from the client so that we can be sure that when the account is added the default is set at the same time. If we were to first add the account, then once added set the default_usd_account_id there's a chance the second step would fail.

[gudnuf]

Related to this, would we ever want to add a checkbox to the add account flow that says "Make default"? This way when a user adds an account they can automatically set it to default when the account is created. Currently, when you want to add an account and make it default you have to first add it, then go to the account details page and click make default. @jbojcic1 if we ever wanted to do this, then I think an add_account function would be best.

@bobscully3 do you have thoughts on this idea for a make default checkbox or something similar?

[jbojcic1]

I think db function is cleaner than trigger. We need to be careful with triggers not to make a mess that's hard to track

[gudnuf]

@claude based on the description and discussion in this issue create a plan using opus 4.5 and provide a spec based plan that I can provide to a coding agent to resolve this issue.

• If you don't have the issue in your context fetch it here New accounts should be set to default when none exist for that currency #734 just using tools you have. Do not use the gh cli tool
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• you should repond here when you have created the plan
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