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#event-driven

2 stories

Banner: AWS Lambda function triggering itself through S3 writes in a recursive loop

Cloud & Infrastructure Bug Report

Lambda writes to the bucket that triggers it: a recursive loop and a cost spike

Ryan Pham · Feb 11, 2026 · 6 min read

A refactor changed one output prefix in an image processing Lambda, and the function started triggering itself. Invocations went from 40,000 a day to 9 million in six hours. We stopped it with reserved concurrency, then separated input and output and added loop guards.

Banner: architecture of an event-driven trading bot with order state machine and risk checks

Engineering Practice

Architecture of a reliable trading bot: events, state machines and reconciliation

Ryan Pham · Dec 9, 2025 · 6 min read

Most trading bot failures we have seen are not strategy bugs; they are state bugs: lost fills, duplicate orders, wrong positions after a restart. This guide describes an architecture that keeps state correct: separated components, an order state machine, persistence, risk checks and reconciliation.