A 25-day feature, delivered in 3
A live fintech platform, rebuilt one workflow at a time by a single engineer directing AI coding agents.
Context
A live fintech platform handling transaction validation and investment workflows for its users. The product was in active use, so every change had to ship without disrupting existing customers.
Problem
Accumulated tech debt in the transaction-validation and investment workflows was generating roughly 15 support tickets a week and slowing down every new feature that touched those paths.
Approach
Each workflow was respecified before it was touched: a formal spec, then test-driven implementation carried out by AI coding agents under direct review — every architectural and correctness decision reviewed and owned by the engineer, not the agents.
One feature scoped at roughly 25 days of traditional development shipped in 3, using this same spec-first, AI-agentic pipeline.
Result
Support tickets on the affected workflows fell from around 15 a week to under 6 — a 60% reduction — and the delivery pace matched what a team of six full-time engineers had previously produced on the same product.
- 3 days
- vs. an estimated 25 days of traditional development for the same feature
- 60% fewer tickets
- From 15 a week to under 6, after the transaction-validation and investment workflows were rebuilt