Loan affordability

A personal-loan application decided on affordability: the applicant answers a short flow, four rules check identity, repayments against income, the amount and repeat applications, and borderline files go to an underwriter. Pack: examples/policies/loan-affordability/.

A pattern for expressing a lending & credit policy, not compliance guidance: the thresholds, lists and fields are placeholders chosen to make the example run; a real policy comes from the business's own rules. It calls no app, so it runs in an empty workspace as it is.

The decision it automates

Whether to offer the loan, refer it to an underwriter, or decline it, at the moment the application is submitted.

Data expected

• The applicant as a subject (kind user) with identityVerified, the result of your identity check, written by your backend before it starts the run.
• The flow's answers under submission: amount, purpose, employment, employerName, monthlyIncome and an optional payslip.
• loan.application events posted through POST /events for each application, so the velocity rule can count them.

Steps and rules

Step	Type	Why
collect	wait_for_collection	The loan-application flow; employed applicants are asked for their employer and a payslip.
rules	evaluate_rules	The loan-affordability rule set under max_severity: a failed block rule declines, a failed warn rule refers.
route	branch	rules.outcome == manual_review opens a case.
review	create_case	loan_underwriting, 48-hour SLA.
decide	emit_decision	From the rules, or the reviewer's decision.

The rule set loan-affordability (useCase: underwriting) uses max_severity: a failed block rule rejects, a failed warn rule sends the run to review, and the weights add up to the score.

Rule	Type	Severity, weight	Fails when
loan_identity_verified	comparison	block, 100	subject.identityVerified is not true
loan_affordability	expression	warn, 40	amount / 36 is more than 35% of monthlyIncome
loan_amount_referral	score threshold	warn, 20	amount is above 25 000
loan_repeat_applications	velocity	warn, 20	more than one loan.application event in 30 days

What a reviewer sees

A loan_underwriting case with the application, the optional payslip and each rule's result. The underwriter's decision and note become the decision and its reasons.

How to adapt it

Read the term from the flow instead of assuming 36 months, add a call_app step for your credit bureau (an app you build with the SDK) and rules over its answer, and backtest a new affordability limit over past applications before publishing it. A doc-verify-mock step on the payslip shows the asynchronous document path (Individual KYC with documents).

Run it

pnpm policy:import examples/policies/loan-affordability --publish

The fixture asks for 12 000 on an income of 900: repayments of 333 a month are above the 315 that 35% allows, so the affordability rule fails, a loan_underwriting case opens, the check approves it and the run completes with a manual approve.