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Capturing token IDs during agentic interactions for better reinforcement learning

Amazon just solved a hidden problem in agent training: token-level visibility. Most teams are flying blind.

Illustration of independent geometric mechanisms passing paper tasks along branching amber tracks.
AI agents and the coordination of work.AI illustration by KeyNews
The KeyNews take

Why it matters

Amazon Science's Turnstile proxy enables fine-grained reinforcement learning on agentic systems by capturing token IDs lost in text-only logs. This addresses a critical gap in agent training methodology that affects model performance at scale.

The key facts

11 to know
  1. Amazon Science introduces Turnstile, a Rust proxy for token ID capture

  2. Designed to capture information lost in text transcripts during agentic interactions

  3. Enables reinforcement learning at token level rather than transcript level

  4. Sits between model backend and agent harness

  5. Published by Amazon Science (credible, peer-facing research division)

  6. New Rust proxy called Turnstile

  7. Captures token IDs during agentic interactions

  8. Designed to retain information lost in text-only transcripts

  9. Focus on reinforcement learning optimization for agents

  10. Published by Amazon Science

  11. Published July 9, 2026

Go to the source

Amazon Scienceamazon.science

Publisher excerpt: A new Rust proxy called Turnstile sits between the model backend and the agent harness to capture information lost in mere text transcripts.
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