Worked on enhancing sandbox environment stability and regionalization across the openai/openai-agents-js and mastra-ai/mastra repositories. Focused on preserving environment resolvers during manifest merges, improving error handling, and refining session lifecycle management to increase reliability for sandbox runs. Introduced region selection for sandbox creation in mastra-ai/mastra, enabling deployments in context-appropriate regions with robust fallback logic. Utilized TypeScript and full stack development skills to implement these changes, along with comprehensive unit testing to ensure reliability. Updated documentation and repository alignment to reflect new behaviors, reducing operational toil and improving predictability for users working with sandbox environments in both repositories.