Is your feature request related to a problem? Please describe.
The Ruby SDK currently stores sessions in memory, which prevents it from supporting stateless backends. This is a scalability issue because session state cannot be shared across nodes. In contrast, the Python SDK supports a stateless configuration value.

Describe the solution you'd like
We'd like the Ruby SDK to support stateless session management, similar to the Python SDK.

Describe alternatives you've considered

• using sticky sessions — this is not something we can pursue
• forking the library — not ideal, but something we can do to unblock
• switching to a different SDK — fast-mcp has no Streamable HTTP support, so this is a non-starter

Additional context
We use a minimum of 2 pods for all services to ensure availability. This feature is critical for us to use the Ruby SDK to build remote MCPs.