[Bug]: Template by schedule incorrectly calculating budgeting amount

[sammichaels]

Verified issue does not already exist?

• I have searched and found no existing issue
• I will be providing steps how to reproduce the bug (in most cases this will also mean uploading a demo budget file)

What happened?

When using a schedule with two transactions per month and a template by schedule, the next month is incorrectly calculated.

Steps to reproduce (calculated on 11/24/24 and 11/25/24):

1. Create schedule with transactions of $100 on the 15th and 30th of every month. Verified upcoming dates listed 11/30, 12/15, 12/30.
2. Add a template by schedule "#template schedule X".
3. Apply for November. Correctly added $100 to category for 11/30.
4. Apply for December. Incorrectly added $100 to category. Expected $200 for the transactions on 12/15 and 12/30.
5. Apply for January. Correctly added $200 to category for 1/15 and 1/30.

I've attached an example budget I created to reproduce the issue.

Where are you hosting Actual?

Docker

What browsers are you seeing the problem on?

Safari

Operating System

Mac OSX

[sammichaels]

The behavior appears to be in goalsSchedule.ts:

actual/packages/loot-core/src/server/budget/goalsSchedule.ts

Lines 227 to 242 in c25e3d4

	if (balance >= totalSinking + totalPayMonthOf) {
	to_budget += Math.round(totalPayMonthOf + totalSinkingBaseContribution);
	} else {
	const totalSinkingContribution = await getSinkingContributionTotal(
	t_sinking,
	remainder,
	last_month_balance,
	);
	if (t_sinking.length === 0) {
	to_budget +=
	Math.round(totalPayMonthOf + totalSinkingContribution) -
	last_month_balance;
	} else {
	to_budget += Math.round(totalPayMonthOf + totalSinkingContribution);
	}
	}

If the balance is less than the amount needed to schedule (if statement on line 227 is evaluating to false), it is incorrectly subtracting last_month_balance from the amount in totalPayMonthOf (setting to_Budget on line 236). I think the issue is that it's not reserving the amount needed for upcoming transactions in previous months that have not yet happened.

In my example above, $100 is added in November, but that transaction has not yet occurred. When December is calculated, it's not taking into consideration the 11/30 upcoming transaction and instead subtracting that balance ($200 total needed for 12/15 and 12/30, $100 already there, so only fund $100). The expected behavior would be $200 total needed for 12/15 and 12/30, $100 already there, $100 needed in upcoming transactions from previous months on 11/30, so fund $200.