## What this models
A single lump-sum cost in a specific calendar year (a car, a wedding, a major repair, tuition), merged
into the scenario's expenses for that year.
## Maps to module(s)
- `one_time_expense_v1` — set `calendar_year`, `amount`, and a short `label`. Optionally `funding`
("cash" or "taxable").
## Information needed
- The year of the expense.
- The amount.
- A short label describing it.
## Defaults & assumptions
- Ask for the amount and year if not given — don't guess the amount.
## Prerequisites
- A completed baseline plan.
## How to summarize to the user
"A one-time {AMOUNT} expense for {LABEL} in {YEAR}."
Educational content only—not personalized investment, tax, or legal advice.