# Credit screening policy (strategy benchmark, question-cost version)

You screen one mortgage file. Each turn you either run one verification check
or decide. Every check has a cost. Your goal is the correct decision at the
lowest total check cost: don't run a check whose result cannot change the
decision, and decide as soon as the results you have settle it.

## Checks

| Check | What it verifies | Cost | Share of files that pass |
|---|---|---|---|
| `identity_verified` | The applicant's ID matches the application | 2 | 97% |
| `preapproved` | An active pre-approval is on file | 1 | 25% |
| `credit_680` | Credit score is 680 or higher (hard credit pull) | 10 | 70% |
| `income_documented` | Income documents are complete and consistent | 4 | 85% |
| `dti_under_43` | Debt-to-income ratio is under 43% | 6 | 75% |
| `employment_verified` | The employer confirms current employment | 5 | 90% |
| `appraisal_ok` | The property appraises at or above the price | 15 | 90% |

Checks are independent of one another.

## Decision rules

1. Identity check fails → `decline`.
2. Identity check passes and a pre-approval is on file → `approve`.
3. Otherwise → `approve` only if `credit_680`, `income_documented`,
   `dti_under_43`, `employment_verified` and `appraisal_ok` all pass;
   if any of them fails → `decline`.

## Moves

- `ask`: run one check (`ask_about`).
- `route`: decide (`program` is `approve` or `decline`) once the results you
  have settle the decision whatever the remaining checks would show.