Understand the failure.
Verify the repair.
Small, reproducible software failures. The broken implementation, the fix that didn’t work, and the one that passed—preserved together.
Explore the cases ↓How results are verified ↗WHAT THE ARCHIVE CONTAINS
100840 executable cases. 20168 are open.
Every case records the implementation that fails, the fix that did not work, and the repair that passed its checks—with recorded outputs and source hashes. This release adds 100840 cases across 20168 failure mechanisms and 254 domains.
The open tier gives you the failure and the unsuccessful fix for one case in every mechanism. The remaining 80672 cases, 5 variants per mechanism, are member-only: the verified repair, its recorded checks, and the full fixture suite are held in the member archive. Read the methodology ↗
A RECORD OF WHAT WENT WRONG
Browse the archive / 100840
Negative amortization cap recast: deferred interest accrual · case 01
Deferred interest shrinks in months where the payment covers interest.
Negative amortization cap recast: deferred interest accrual · case 02
Deferred interest shrinks in months where the payment covers interest.
Negative amortization cap recast: deferred interest accrual · case 03
Deferred interest shrinks in months where the payment covers interest.
Negative amortization cap recast: deferred interest accrual · case 04
Deferred interest shrinks in months where the payment covers interest.
Negative amortization cap recast: deferred interest accrual · case 05
Deferred interest shrinks in months where the payment covers interest.
Negative amortization cap recast: cap check timing · case 01
The recast is detected a month after the balance crosses the cap.
Negative amortization cap recast: cap check timing · case 02
The recast is detected a month after the balance crosses the cap.
Negative amortization cap recast: cap check timing · case 03
The recast is detected a month after the balance crosses the cap.
Negative amortization cap recast: cap check timing · case 04
The recast is detected a month after the balance crosses the cap.
Negative amortization cap recast: cap check timing · case 05
The recast is detected a month after the balance crosses the cap.
Negative amortization cap recast: balance roll-forward · case 01
Payments above interest never reduce the balance.
Negative amortization cap recast: balance roll-forward · case 02
Payments above interest never reduce the balance.
Negative amortization cap recast: balance roll-forward · case 03
Payments above interest never reduce the balance.
Negative amortization cap recast: balance roll-forward · case 04
Payments above interest never reduce the balance.
Negative amortization cap recast: balance roll-forward · case 05
Payments above interest never reduce the balance.
Rule of 78s early payoff rebate: remaining digits numerator · case 01
Early payoffs receive a smaller rebate than the sum-of-digits formula gives.
Rule of 78s early payoff rebate: remaining digits numerator · case 02
Early payoffs receive a smaller rebate than the sum-of-digits formula gives.
Rule of 78s early payoff rebate: remaining digits numerator · case 03
Early payoffs receive a smaller rebate than the sum-of-digits formula gives.
Rule of 78s early payoff rebate: remaining digits numerator · case 04
Early payoffs receive a smaller rebate than the sum-of-digits formula gives.
Rule of 78s early payoff rebate: remaining digits numerator · case 05
Early payoffs receive a smaller rebate than the sum-of-digits formula gives.
Rule of 78s early payoff rebate: total digits denominator · case 01
Rebates are overstated for every payoff.
Rule of 78s early payoff rebate: total digits denominator · case 02
Rebates are overstated for every payoff.
Rule of 78s early payoff rebate: total digits denominator · case 03
Rebates are overstated for every payoff.
Rule of 78s early payoff rebate: total digits denominator · case 04
Rebates are overstated for every payoff.
Rule of 78s early payoff rebate: total digits denominator · case 05
Rebates are overstated for every payoff.
Rule of 78s early payoff rebate: acquisition fee exclusion · case 01
The fully earned acquisition fee is partly rebated.
Rule of 78s early payoff rebate: acquisition fee exclusion · case 02
The fully earned acquisition fee is partly rebated.
Rule of 78s early payoff rebate: acquisition fee exclusion · case 03
The fully earned acquisition fee is partly rebated.
Rule of 78s early payoff rebate: acquisition fee exclusion · case 04
The fully earned acquisition fee is partly rebated.
Rule of 78s early payoff rebate: acquisition fee exclusion · case 05
The fully earned acquisition fee is partly rebated.
Rule of 78s early payoff rebate: minimum rebate threshold · case 01
A rebate exactly at the minimum is suppressed.
Rule of 78s early payoff rebate: minimum rebate threshold · case 02
A rebate exactly at the minimum is suppressed.
Rule of 78s early payoff rebate: minimum rebate threshold · case 03
A rebate exactly at the minimum is suppressed.
Rule of 78s early payoff rebate: minimum rebate threshold · case 04
A rebate exactly at the minimum is suppressed.
Rule of 78s early payoff rebate: minimum rebate threshold · case 05
A rebate exactly at the minimum is suppressed.
Rule of 78s early payoff rebate: remaining installment count · case 01
Payoff quotes omit one remaining installment and its rebate.
Rule of 78s early payoff rebate: remaining installment count · case 02
Payoff quotes omit one remaining installment and its rebate.
Rule of 78s early payoff rebate: remaining installment count · case 03
Payoff quotes omit one remaining installment and its rebate.
Rule of 78s early payoff rebate: remaining installment count · case 04
Payoff quotes omit one remaining installment and its rebate.
Rule of 78s early payoff rebate: remaining installment count · case 05
Payoff quotes omit one remaining installment and its rebate.
Rule of 78s early payoff rebate: earned charge · case 01
Earned finance charge omits the acquisition fee.
Rule of 78s early payoff rebate: earned charge · case 02
Earned finance charge omits the acquisition fee.
Rule of 78s early payoff rebate: earned charge · case 03
Earned finance charge omits the acquisition fee.
Rule of 78s early payoff rebate: earned charge · case 04
Earned finance charge omits the acquisition fee.
Rule of 78s early payoff rebate: earned charge · case 05
Earned finance charge omits the acquisition fee.
Payoff quote with per diem: per diem rounding stage · case 01
Payoff interest does not equal the quoted per diem times the days.
Payoff quote with per diem: per diem rounding stage · case 02
Payoff interest does not equal the quoted per diem times the days.
Payoff quote with per diem: per diem rounding stage · case 03
Payoff interest does not equal the quoted per diem times the days.
Payoff quote with per diem: per diem rounding stage · case 04
Payoff interest does not equal the quoted per diem times the days.
Payoff quote with per diem: per diem rounding stage · case 05
Payoff interest does not equal the quoted per diem times the days.
Payoff quote with per diem: interest day count · case 01
Payoff quotes charge one extra day of interest.
Payoff quote with per diem: interest day count · case 02
Payoff quotes charge one extra day of interest.
Payoff quote with per diem: interest day count · case 03
Payoff quotes charge one extra day of interest.
Payoff quote with per diem: interest day count · case 04
Payoff quotes charge one extra day of interest.
Payoff quote with per diem: interest day count · case 05
Payoff quotes charge one extra day of interest.
Payoff quote with per diem: penalty window · case 01
Payoffs on the last day of the penalty window escape the prepayment penalty.
Payoff quote with per diem: penalty window · case 02
Payoffs on the last day of the penalty window escape the prepayment penalty.
Payoff quote with per diem: penalty window · case 03
Payoffs on the last day of the penalty window escape the prepayment penalty.
Payoff quote with per diem: penalty window · case 04
Payoffs on the last day of the penalty window escape the prepayment penalty.
Payoff quote with per diem: penalty window · case 05
Payoffs on the last day of the penalty window escape the prepayment penalty.
Payoff quote with per diem: escrow credit · case 01
Escrow balances increase the payoff amount.
Payoff quote with per diem: escrow credit · case 02
Escrow balances increase the payoff amount.
Payoff quote with per diem: escrow credit · case 03
Escrow balances increase the payoff amount.
Payoff quote with per diem: escrow credit · case 04
Escrow balances increase the payoff amount.
Payoff quote with per diem: escrow credit · case 05
Escrow balances increase the payoff amount.
Payoff quote with per diem: penalty base · case 01
The prepayment penalty is charged on accrued interest as well as principal.
Payoff quote with per diem: penalty base · case 02
The prepayment penalty is charged on accrued interest as well as principal.
Payoff quote with per diem: penalty base · case 03
The prepayment penalty is charged on accrued interest as well as principal.
Payoff quote with per diem: penalty base · case 04
The prepayment penalty is charged on accrued interest as well as principal.
Payoff quote with per diem: penalty base · case 05
The prepayment penalty is charged on accrued interest as well as principal.
Annual escrow analysis: cushion computation · case 01
Cushions drift by a few cents from the annual formula.
Annual escrow analysis: cushion computation · case 02
Cushions drift by a few cents from the annual formula.
Annual escrow analysis: cushion computation · case 03
Cushions drift by a few cents from the annual formula.
Annual escrow analysis: cushion computation · case 04
Cushions drift by a few cents from the annual formula.
Annual escrow analysis: cushion computation · case 05
Cushions drift by a few cents from the annual formula.
Annual escrow analysis: shortage spread rounding · case 01
Twelve shortage installments do not recover the whole shortage.
Annual escrow analysis: shortage spread rounding · case 02
Twelve shortage installments do not recover the whole shortage.
Annual escrow analysis: shortage spread rounding · case 03
Twelve shortage installments do not recover the whole shortage.
Annual escrow analysis: shortage spread rounding · case 04
Twelve shortage installments do not recover the whole shortage.
Annual escrow analysis: shortage spread rounding · case 05
Twelve shortage installments do not recover the whole shortage.
Annual escrow analysis: refund threshold test · case 01
A surplus exactly at the threshold is not refunded.
Annual escrow analysis: refund threshold test · case 02
A surplus exactly at the threshold is not refunded.
Annual escrow analysis: refund threshold test · case 03
A surplus exactly at the threshold is not refunded.
Annual escrow analysis: refund threshold test · case 04
A surplus exactly at the threshold is not refunded.
Annual escrow analysis: refund threshold test · case 05
A surplus exactly at the threshold is not refunded.
Annual escrow analysis: credit after refund · case 01
Borrowers receive a refund and a monthly credit for the same surplus.
Annual escrow analysis: credit after refund · case 02
Borrowers receive a refund and a monthly credit for the same surplus.
Annual escrow analysis: credit after refund · case 03
Borrowers receive a refund and a monthly credit for the same surplus.
Annual escrow analysis: credit after refund · case 04
Borrowers receive a refund and a monthly credit for the same surplus.
Annual escrow analysis: credit after refund · case 05
Borrowers receive a refund and a monthly credit for the same surplus.
Annual escrow analysis: monthly base rounding · case 01
The monthly escrow deposit is a cent short for many tax bills.
Annual escrow analysis: monthly base rounding · case 02
The monthly escrow deposit is a cent short for many tax bills.
Annual escrow analysis: monthly base rounding · case 03
The monthly escrow deposit is a cent short for many tax bills.
Annual escrow analysis: monthly base rounding · case 04
The monthly escrow deposit is a cent short for many tax bills.
Annual escrow analysis: monthly base rounding · case 05
The monthly escrow deposit is a cent short for many tax bills.
Annual escrow analysis: low point comparison · case 01
Escrow accounts with plenty of funds are told they have a shortage.
Annual escrow analysis: low point comparison · case 02
Escrow accounts with plenty of funds are told they have a shortage.
Annual escrow analysis: low point comparison · case 03
Escrow accounts with plenty of funds are told they have a shortage.
Annual escrow analysis: low point comparison · case 04
Escrow accounts with plenty of funds are told they have a shortage.
Annual escrow analysis: low point comparison · case 05
Escrow accounts with plenty of funds are told they have a shortage.
INSPECTABLE BY DESIGN
Every result has a runnable source.
Runnable implementations with recorded outputs, source hashes, and explicit contracts. Related variants share a failure mechanism and belong together in evaluation splits.
Read the methodology ↗