How One Backend Team's Post-Mortem Revealed Why Their AI Agent Audit Logging Strategy Collapsed Under Regulatory Scrutiny , And the Tamper-Evident, Compliance-Ready Event Sourcing Architecture They Built to Survive It in 2026

It started with a routine regulatory review. It ended with a three-week scramble, two engineer burnouts, and a compliance gap so wide that the legal team briefly considered halting the product entirely. The team in question: a seven-person backend engineering group at a mid-sized fintech SaaS company we will call