Designing Custom Reward Functions for Multi-Turn RL in Amazon Nova Forge

Maria Masood· August 14, 2026 View original

Key takeaways

  • Custom reward functions are central to effective multi-turn reinforcement learning.
  • Composite reward functions allow for nuanced guidance of AI model behavior.
  • Safe execution of model-generated code within reward functions is a critical security consideration.
  • Instrumentation helps diagnose and prevent reward function collapse.

Who benefits

Software DevelopmentAI/ML EngineeringGamingCustomer ServiceRobotics

Summary

This post details how to create composite multi-turn reward functions for Amazon Nova Forge, including safe execution of model-generated code and instrumentation to prevent reward function failures. It emphasizes the critical role of reward functions in guiding model learning in multi-turn reinforcement learning.

The article provides a guide on developing sophisticated reward functions for multi-turn reinforcement learning (RL) within Amazon Nova Forge. It highlights that these custom functions are crucial for dictating what an RL model ultimately learns. The content covers the process of constructing a composite reward system, ensuring the secure execution of code generated by the model, and implementing monitoring tools for each component. This instrumentation is vital for identifying and mitigating issues that could subtly undermine the effectiveness of the reward mechanism.

Why it matters

Professionals working with advanced AI models need to understand how to precisely control model behavior, and custom reward functions are key to achieving desired outcomes in complex multi-turn interactions.

How to implement this in your domain

  1. 1Define clear objectives for your multi-turn RL agent to inform reward function design.
  2. 2Design a composite reward function, breaking down complex goals into measurable sub-components.
  3. 3Implement safety measures for executing model-generated code within the reward function environment.
  4. 4Instrument each component of the reward function to monitor its performance and identify potential issues.
  5. 5Iteratively test and refine the reward function based on agent behavior and observed outcomes.

Original post by Maria Masood

"In multi-turn reinforcement learning, your custom reward function decides what the model actually learns. This post shows how to design a composite multi-turn reward for Amazon Nova Forge, execute model-generated code safely inside it, and instrument each component to catch the p…"

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