Transaction fraud scorer¶

XGBoost model producing fraud probability on each transaction in <200ms. ≥0.85 auto-decline. 0.60–0.85 step-up auth. <0.60 pass. See ADR-010.

Module dependencies¶

Module	Title	Required?	Contract	Reason
MOD-042	CDC pipeline — Neon logical replication to S3 Iceberg	Required	—	Fraud model is trained and scored on transaction history fed through the CDC pipeline to Snowflake.
MOD-024	Device & session intelligence	Optional	—	Device and session intelligence signals improve fraud score accuracy by adding behavioural context.
MOD-104	AWS shared infrastructure bootstrap	Required	—	AWS shared infrastructure provisioned by MOD-104 (EventBridge buses, S3, KMS, Kinesis, Cognito) is required before this module can be deployed.
MOD-103	Neon database platform bootstrap	Required	—	Neon database and schema provisioned by MOD-103 must exist before this module can read or write Postgres.

Module	Title	As	Contract
MOD-020	Pre-payment validation suite	Hard dependency	—
MOD-119	BPAY payment integration	Hard dependency	—
MOD-120	PayID and Osko integration	Hard dependency	—
MOD-122	NZ faster payments and A2A integration	Hard dependency	—
MOD-123	ATM network integration	Hard dependency	—
MOD-141	Intra-bank transfer engine	Hard dependency	—

Policy	Title	Mode	How
PAY-005	Payment Fraud Prevention Policy	`AUTO`	Fraud model runs on every transaction — not sampled. Score and decision logged.
CON-001	Customer Fairness & Conduct Policy	`AUTO`	Customers protected from fraud automatically — not reliant on reporting it after the fact
DT-005	Model Risk Management Policy	`LOG`	Fraud model versioned, validated, and performance-monitored in Snowflake

Capability	Title	Mode	How
CAP-022	Unusual transaction alert	`ALERT`	Raises an alert for the customer when a transaction score exceeds the unusual-activity threshold.
CAP-038	Real-time fraud scoring & block	`GATE`	Blocks any payment instruction where the real-time fraud score exceeds the configured threshold — the block occurs before the transaction reaches the ledger.
CAP-040	Scam warning system (payee risk scoring)	`ALERT`	Scores payees against scam risk signals and surfaces a warning to the customer before they confirm a payment to a high-risk recipient.

Part of SD04 — Payments Processing Platform Compiled 2026-05-22 from source/entities/modules/MOD-023.yaml