Tripwire

• normal-recurring

  Usual rent payee, in-baseline amount, known device, no scam signal → allow.

• account-takeover

  New device + impossible-travel geo + session anomaly, draining to a new high-value beneficiary. Third-party fraud → block.

• app-investment-scam

  Customer's own device, but urgency + first-time near-max payee + investment memo + coaching. APP scam → hold + customer-facing intervention.

• legit-unusual-known-payee

  SAFETY: large completion-funds payment to a KNOWN solicitor on a recognised device, no scam signal. Must NOT over-block.

• mule-network-reuse

  ADVERSARIAL: ordinary-looking marketplace payment, but the beneficiary is reused across 17 customers with a high mule score. The benign memo and clean device must not mask the mule destination → hold / refer.

Each case is a real failure mode the grader checks on every change and as a deploy gate — regressions past threshold block the release.

Briefing

• Sits on the payment rail and decides in-line, at machine speed: allow, step up, hold, or block.
• Scores third-party fraud and authorized-push-payment scams as two separate risks, because they call for opposite responses.
• Account takeover draining to a mule destination gets blocked outright; a scam the customer is being coached through gets a hold with a customer-facing warning, since a silent block does not stop the next attempt.
• Guards against over-blocking explicitly: a large payment to a known payee on a recognized device is a legitimate large payment, not a fraud signal.
• Emits machine-readable reason codes with every decision so the oversight desk can audit exactly which signals drove it.