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Real-time payments

Curated insights and technical field notes on Real-time payments.

Current note

The 11:47am question real-time rails ask of your ledger

The newest published argument and its visual artifact lead the page.

Editorial posture

The library is organized around decisions that keep recurring in payment architecture, AI systems, and Doric product work. New notes lead by publish date, while topic lanes connect related arguments without turning the index into an archive wall.

Decision frame

Recommendation, rejected paths, and the operating proof behind the call.

Visual proof

Diagrams and original artifacts stay near the argument they explain.

Source posture

Public claims stay tied to released work or cited material.

Architecture

The 11:47am question real-time rails ask of your ledger

What was the cash position at 11:47am? On a snapshot-based model the honest answer is an interpolation between two saved states. Real-time rails turned that guess into a liability, and the fix is to stop storing a position at all and fold an immutable event log into the answer. The event log is not free, and most teams have not put the bill on the budget.

Lead essay

The current Doric argument leads the index ahead of the chronological archive.

Read the note

01 / Payments

Commerce architecture

Merchant-of-record decisions, checkout ownership, billing operations, settlement, reconciliation, and risk boundaries.

02 / AI tooling

Practical AI systems

Agentic commerce, multi-agent orchestration, model fine-tuning, runtime governance, and production deployment.

03 / Build notes

From idea to system

The design, architecture, and operating decisions behind Doric Stack products as they move from prototype to public release.

Latest Notes

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Sep 16, 2025 By Navin Agrawal Architecture 3 min read

Payroll virtual accounts break on the real-world edge cases

A clean virtual-account hierarchy looks simple until an HCM client asks you to reverse payroll for 200 employees across three states from three weeks ago. Multi-entity payroll is where account architecture meets 50 sets of wage law - and where instant rails do not yet fit.

Aug 4, 2025 By Navin Agrawal Payments 3 min read

Instant rails broke the treasury day

ACH cleared overnight, wires ran on business hours, and float was predictable. FedNow and RTP ended that. With 42 percent of RTP payments landing nights, weekends, and holidays, treasury teams are positioning cash by the hour - and the Fed discount window still keeps bankers' hours.

Jul 7, 2025 By Navin Agrawal Payments 3 min read

APP fraud: real-time payments solved the wrong problem

Instant rails stripped out the friction that quietly prevented massive losses - and authorized push payment fraud walked straight through the gap. Once the money hits the rail it is gone, and multi-factor authentication cannot help when the victim authorizes the payment themselves.