8 Agents Wrote Perfect Components - And Nothing Worked

TL;DR: Parallel AI agents don't coordinate on shared contracts, such as column names, URL paths, parameter formats, or identifiers. Extract those contracts into a single reference file before generation, and run a review agent that traces end-to-end data flows once the parallel agents are done. This single step fixed all 17 bugs in one pass. I launched 8 AI agents in parallel to build a full-stack app on AWS: infrastructure stacks, a React frontend, and a Java backend. Each agent owned one piece, and they all delivered clean, compiling code. The CDK type-checked, the Java backend followed Spring Boot conventions, the React UI looked nice. But when I tried to wire them together I hit bugs at every single boundary. The architecture A full-stack app on AWS with a lot of moving parts. Multiple CDK stacks for the infrastructure (IAM, VPC, DB with seed functions, Cognito, CodePipeline, CloudFront/WAF), a Spring Boot backend on ECS Fargate, and a React frontend hosted on S3. The implementatio