Layers Made It Universal. Harnesses Made It Run

A continuation of Flip the Axis: A Layer-Based Approach to Multi-Service Migrations . TL;DR You can't script your way across a fleet of snowflake repositories. Neither can you just ask an AI agent to "migrate this service" and hope. What worked for the eight-quarter migration was a harness -- a prompt pipeline in which each layer was a sequence of ordered steps: some calling scripts for deterministic changes, some using AI to discover and adapt, and some validating the results. The harness chain