1. Introduction
Most public demonstrations of AI coding agents begin with an empty directory and end when a visible feature works. That is useful, but it measures only the first and easiest part of software engineering: generation. Real projects are stateful. They contain existing behavior, data that must survive, security boundaries, partially completed work, and verification steps that cannot be replaced by a convincing demo.
This benchmark was designed as a small, practical record of that harder problem. It documents two Codex runs on the same full-stack task-manager project. Phase 1 was a greenfield build. Phase 2 returned to the existing application for an authentication and database-migration refactor. The second run also included a long, user-initiated interruption, making recovery part of the observed workflow.
The narrow result is encouraging: the initial application was recorded as complete in approximately 34 minutes, and the later refactor took approximately 42 minutes of active execution, excluding the user-initiated pause. The Phase 2 run reported 16 backend tests, 1 legacy-migration test, and 25 frontend tests passing, along with lint, type, build, dependency, and browser-acceptance checks.
