The rearview mirror analogy is spot on. Traditional budgeting tells you what happened, cash flow forecasting tells you when you'll actually hit the wall.
The tricky bit is handling irregular income and timing uncertainty. Are you modeling confidence intervals or just point estimates? Most forecasting tools I've seen fall apart when income isn't predictable - would be curious how you're approaching that.
thanks for comment! i'm tracking both irregular and regular income/expense via common frequencies: weekly, bi-weekly, semi-monthly, monthly, quarterly, annually. Then that income/expense shows up appropriately on the Money Calendar with projected running balance. so even if irregular (either income or expense) you can easily see it play out in the calendar. so nothing too fancy on the technical end. user just needs to pick a frequency and/or insert one-off income/expenses as needed. I use this obsessively and find it works well.
The tricky bit is handling irregular income and timing uncertainty. Are you modeling confidence intervals or just point estimates? Most forecasting tools I've seen fall apart when income isn't predictable - would be curious how you're approaching that.