OpenAI Updates Agents SDK to Support Secure Sandboxes and Durable Execution

Apr 15, 2026 · Updated Apr 25, 2026

OpenAI released a major update to its Agents SDK, introducing a model-native harness (the core engine managing the agent loop) and native sandbox execution. The harness is optimized for frontier models to handle long-horizon tasks, while the sandbox provides a secure environment where agents can safely run commands, edit files, and install dependencies.

Building reliable agents currently requires complex infrastructure to manage state and security. This update standardizes the agent stack by decoupling the harness from compute, which prevents credential leaks and enables durable execution. If a sandbox fails, the harness can rehydrate (restore state from a snapshot) in a fresh container and continue without losing progress.

You can now build agents that integrate with MCP and use AGENTS.md for instructions. The SDK supports sandbox providers like E2B and Vercel out of the box. These features are generally available to API customers in Python, with TypeScript support coming soon.

View the full update on openai.com

OpenAI Developers

@OpenAIDevsApr 15

Build long-running agents with more control over agent execution. New capabilities in the Agents SDK: • Run agents in controlled sandboxes • Inspect and customize the open-source harness • Control when memories are created and where they’re stored https://t.co/zPyuLup6b6

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