Indian lending lifecycle¶

The full Underwrite underwriting journey, end-to-end, against an in-memory runtime. Twelve stages from onboarding to origination — each one a nano-service, each transition a typed event, each event carrying the runtime guarantees into the next stage.

This page is the primary mental model for the platform. The same flow runs in production against Sqlite + OTLP + Vault; here it runs in a single Python process with no broker, no cluster, no external dependencies.

The flow¶

01

Onboarding¶

The mechanism service seeds capital and creates a sponsor → borrower pair. The first durable identity. seed.added · user.added

02

Identity¶

PAN and Aadhaar identifiers attach to the borrower. The identity service emits an attestable identity-registered event. identity.registered

03

DPDPA consent is recorded with a specific purpose (KYC verification). Withdrawable at any time. The consent service enforces re-consent on purpose change. consent.recorded

04

KYC¶

PAN format validation, Aadhaar Verhoeff checksum, AML risk score, CKYC registry trigger. Wire-protocol clients against NSDL / UIDAI / Karza. kyc.verified

05

AML¶

Sanctions screening, transaction pattern checks, risk scoring. AML clears or freezes; the runtime routes to the next stage or to the DLQ with a recorded error. aml.cleared · aml.flagged

06

Credit bureau¶

CIBIL / Experian / Equifax pull. The credit_bureau service emits a normalized credit_bureau.checked event regardless of which bureau responded. credit_bureau.checked

07

Underwriting¶

Rule engine + ML risk model evaluate the application against business rules. Approved, rejected, conditional, or escalated. underwriter.approved · underwriter.rejected

08

Pricing¶

RBI rate caps applied. All-in-cost APR (interest + fees + GST + insurance) computed. EMI, total interest, processing fee emitted. pricing.computed

09

Compliance¶

Cooling-off period enforced. Breach checks run. Compliance emits kfs.generated and gates the next stage. kfs.generated

10

KFS¶

Key Fact Statement issued to the borrower — a complete, versioned disclosure of every pricing and consent fact. kfs.generated

11

Mandate¶

e-NACH / UPI Autopay mandate collection. Roadmap item — not yet wired to a partner. When enabled, the razorpay service emits mandate events. razorpay.mandate.active (planned)

12

Origination¶

The mechanism service books the loan. The audit service persists a redacted copy. The NPA classifier starts watching. The lifecycle is complete. loan.originated

What the runtime adds at every transition¶

Concern	Where it attaches	What it adds
Signing	`Core.emit`	Ed25519 over canonical bytes; deterministic across processes
Verification	`Core.dispatch`	Signature checked before handler runs
Idempotency	`Core.dispatch`	Duplicates dropped silently; cache bounded
Tracing	`Core.handle_event`	Span lifecycle, parent / child propagation
Metrics	`Core.handle_event`	Counters, timers, gauges per service and event type
Authz	`Core.dispatch` + `Core.emit`	Default-deny policy evaluation
DLQ	`LocalBus.dispatch`	Failed events captured with original error
Circuit breaking	`LocalBus.dispatch`	Per-subscriber breaker; OPEN after threshold
Saga coordination	`Orchestrator`	Multi-step workflows with compensating rollback

These guarantees are not optional. Every Core-derived service inherits them through the dispatch pipeline; there is no way for a service to opt out, and no way for a service to write the dispatch logic itself.

Compliance responsibility by stage¶

Stage	Responsibility
Onboarding	KYC for the sponsor; sponsor authorization
Identity	Identity verification; re-attestation on key rotation
Consent	DPDPA consent validity; purpose binding; withdrawal
KYC	PAN format, Aadhaar Verhoeff, AML risk score
AML	Sanctions screening; PEP screening; transaction patterns
Credit bureau	Bureau response normalization; consent re-check
Underwriting	Business rules; model versioning; explainability
Pricing	RBI rate caps; all-in-cost APR disclosure
Compliance	Cooling-off; KFS issuance before disbursement
KFS	Complete disclosure; version pinning
Mandate	e-NACH / UPI Autopay consent; revocation handling
Origination	Audit ledger; NPA classifier activation

Visualizing the flow¶

sequenceDiagram
    participant B as Borrower
    participant M as mechanism
    participant ID as identity
    participant CO as consent
    participant KY as compliance
    participant CR as credit_bureau
    participant U as underwriter
    participant PR as pricing
    participant K as kfs
    participant AU as audit

    B->>M: add_user
    M->>AU: user.added
    B->>CO: record_consent
    CO->>AU: consent.recorded
    B->>KY: kyc_check
    KY->>AU: kyc.verified
    B->>CR: credit_check
    CR->>AU: credit_bureau.checked
    B->>U: evaluate
    U->>AU: underwriter.approved
    B->>PR: compute
    PR->>AU: pricing.computed
    B->>K: generate
    K->>AU: kfs.generated
    B->>M: originate
    M->>AU: loan.originated

Every event flows through audit — the persistent, PII-redacted record of the run.