MCP removed stream resumability — a dropped connection now loses the in-flight request, and clients MUST retry with a new request ID

Model Context Protocol·medium signalXBlueskyLinkedInCopy link

SEP-2575 strips SSE stream resumability and message redelivery (the `Last-Event-ID` header and SSE event IDs) from Streamable HTTP; a broken response stream loses the request outright. Long-running work moves to the `io.modelcontextprotocol/tasks` extension, which now polls via `tasks/get`, adds `tasks/update` for client-to-server input, drops `tasks/list`, and lets servers return task handles unsolicited. Server-to-client change notifications move to a single `subscriptions/listen` POST stream that clients opt into by type. Practical consequence: any MCP tool call longer than your network's patience needs to be idempotent and task-handle-based, because the transport no longer resumes it for you.