Library of Expertise

Field Notes

Decision notes on payments, AI tools, and product architecture, written for people who need to choose a path rather than collect takes.

Reader guide

Start with the newest decision note, then follow the topic lanes when you need payments, AI systems, or product architecture depth.

Decision notes

Clear recommendation, rejected paths, and proof trail.

Systems maps

Visual artifacts sit near the section they explain.

Source posture

Public claims stay tied to released work or cited material.

Strategy

BRICS payment rails are real, and they are at pilot scale

Five central banks are testing a settlement platform that does not touch SWIFT or the dollar. mBridge has been live since 2022, reached minimum viable product in mid-2024, and has moved about 55 billion dollars across roughly 4,000 transactions. SWIFT moves about 53 million messages on an average day. These are parallel rails for specific corridors, and infrastructure moves at infrastructure speed, not headline speed.

Lead essay

Start here when you want the current Doric argument instead of a chronological archive.

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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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By Navin Agrawal Strategy 3 min read

The core was never the bottleneck. The operating model was

The plan said twelve months and the core replacement landed in year three. Nobody in that room was lying. They budgeted for a software install and got an operating-model change. After two decades on the payments, treasury, and integration side of these programs, here is the math I give clients before they sign a full legacy core replacement, and where the months actually go.

By Navin Agrawal Architecture 2 min read

The broker pattern is older than the agentic-commerce headline

Stripe Shared Payment Tokens are the agentic-commerce headline, but anyone who ran a card tokenization rollout in 2014 recognizes the shape in five seconds. A scoped surrogate credential with a thin stable interface in front and brokered complexity behind is not new. Visa Token Service shipped it twelve years ago, and the architects who see the pattern early build the right systems instead of rebuilding every eighteen months.

By Navin Agrawal AI systems 3 min read

Context rot can start before the first prompt

My LLM session loaded 276,989 tool-schema tokens before I typed anything - eleven MCP servers, 609 tool definitions, 27.7 percent of a million-token window spent on payload the model might never call. A bigger context window did not fix that, it gave the problem more room. So I built mcp-broker, PgBouncer for MCP, and the always-loaded tool payload dropped by more than 80 percent.