Reflena evaluates the robustness of code-generation agents by testing their ability to implement scientific and numerical computing functions under strict correctness and execution constraints. Given a problem description and function signature, participant agents generate Python implementations that are evaluated against a structured benchmark consisting of core, edge, noisy, and hard test cases. The green agent enforces response time limits, executes candidate code in isolated processes, and scores results using weighted correctness. The benchmark is designed to expose numerical instability, fragile logic, and failure handling issues that are not captured by standard unit test only evaluations.