dual-era

One server factory, both protocol eras (2025 initialize and 2026-07-28 per-request envelope), both transports (stdio and Streamable HTTP). The client connects once as a plain 2025 client and once with versionNegotiation: { mode: 'auto' }; the same greet tool answers both and reports which era served the call.

This is the recommended first example to read if you are migrating an existing server to the 2026 era: the entry (serveStdio / createMcpHandler) owns the era decision, the factory is era-agnostic.

pnpm tsx examples/dual-era/client.ts                              # stdio
pnpm tsx examples/dual-era/server.ts --http --port 3000           # term 1
pnpm tsx examples/dual-era/client.ts --http http://127.0.0.1:3000/ # term 2

Source: examples/dual-era/README.md