Support MCP client session resumption (sessionId reuse) in Python SDK

Description

Summary

The Python MCP SDK currently appears to create a new session whenever a client is instantiated. It would be valuable to support resuming an existing MCP session using a previously issued sessionId, similar to functionality discussed and addressed in the C# SDK (see modelcontextprotocol/csharp-sdk#946).

This would enable persistent and stateful workflows in agent-based systems.

Problem

At present, there does not appear to be a documented way in the Python SDK to:

• Reuse an existing sessionId
• Resume a previously established MCP session
• Control session lifecycle independently of the client object's lifetime

Why This Is Important

• In agent-driven architectures , session continuity allows:
• More efficient orchestration
• Reduced overhead from repeated session initialization

As MCP adoption grows across SDKs (C#, TypeScript, Python), having consistent session lifecycle capabilities improves cross-language parity and developer experience.

References

https://github.com/modelcontextprotocol/csharp-sdk/issues/946

先追蹤 Python SDK 如何建立及管理用戶端工作階段，然後檢視連結的 C# SDK issue，以了解工作階段恢復的脈絡。完成後應包括一種受支援的方式來重新使用先前簽發的 sessionId、獨立於用戶端生命週期恢復工作階段，以及記錄相關行為。