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Writing
Notes on payment systems, device software, transaction uncertainty, platform design, and the emerging role of AI in commerce. I write from the questions that appear in real operating conditions.
The interchange bill is the visible part. What actually shows up on the underlying scheme fee statement is where the interesting rebalancing is happening.
Merchant support workflows involve looking things up, running checks, and drafting responses. Tool-calling turns an LLM into a first-line agent for well-shaped tasks.
The absence of chargebacks is a feature and a gap. Design patterns for merchant refund flows in a rail with no consumer dispute mechanism.
The insider threat model is different from the external one. Where the discipline usually breaks down.
Sharding a database is often the wrong first move. When it isn't, the choice of shard key is the decision you can't undo.
Saying yes is easier in the moment. Learning to say no well is one of the highest-leverage skills for engineering leaders.
Pushing firmware to a fleet is easy in a lab and hard in the field. What actually goes wrong at scale.
The digital payments story misses the operator on the corner. Some design considerations for cash-out that don't come up in western integrations.
The FATF Travel Rule requires VASPs to share originator and beneficiary information on transfers. Two years in, the compliance patterns are converging.
Anywhere a merchant or customer supplies input that reaches an LLM, prompt injection is a live threat. A field taxonomy of the attack surface.