Keeping MCP server sessions alive after restarts

The MCP Python SDK includes a basic event store for reconnecting after a dropped connection, but it keeps data only in memory. That is fine for development, but a restart, redeploy, or switch to another worker can quietly erase session state. The client may not see a clear error, so work that should continue from the last point can start over.

mcp-persist is built to reduce that problem. It adds SQLite, Redis, and PostgreSQL storage so session information survives outside the running server process and can work across multi-worker deployments. When a client reconnects with Last-Event-ID, it can continue from the point where it stopped.

A proxy mode can also add this behavior in front of MCP servers that cannot be changed directly. In about two weeks since launch, it has passed 8,000 downloads, has one confirmed production use, and has received feedback about TTL edge cases.