calculate_refi_breakeven

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Calculation, not advice. Verify with a professional before acting. Deterministic mortgage refinance break-even analysis. Given your current loan (balance, rate, remaining term) and a refinance offer (new rate, new term, closing costs, optional points), computes: - monthly P&I savings; - the cash-flow break-even month (Senaro's formula: total refinance cost divided by monthly savings, rounded up to a whole month, built on the payback test the CFPB toolkit describes); - the interest delta over your remaining-term horizon, and each loan's interest over its whole schedule (the current loan's remaining term, the new loan's full term); - a term-matched scenario that isolates the rate cut from a term reset; - a term-reset-trap flag (a longer term and a lower payment, but more interest over the new loan's full term than over the current loan's remaining term); and - the economic break-even (net-worth crossover) month under an equal-outflow model: both sides spend the same each month; the side that keeps the current loan starts with the upfront refinance cost invested at month 0 (nothing when costs are rolled in); money not spent on a payment is invested at investment_return_pct. The search runs to the end of the longer loan term, and stops earlier where a loan's term ends with money still owed. Rate-and-term refis only (cash-out and tax effects are out of scope). Pick this when refinancing your existing mortgage into a new rate and term is the question; pick `compare_mortgage_terms` when comparing two mortgage structures on a purchase you have not yet taken out. All defaults cite primary sources (LodeStar/ALTA closing-cost data, the CFPB toolkit's payback test). Scalar output, no chart series. payoff_months and payoff_month_shift use {status, value, explanation}; the two break-evens use {code, month, explanation}.