Six Claude sessions were each spawning their own copy of every stdio server in .mcp.json: 84 node processes and 3 GB of swap on an 8 GB Mac. mcp-hub starts each shared server on first use, renumbers request ids so sessions can't collide, serves it at 127.0.0.1:7788/mcp/<name>, and stops it after 30 idle minutes. Per-session servers (acin, the coaches, venue) stay stdio. A machine opts in with local-scope overrides, so the shared .mcp.json keeps working where the hub isn't installed. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>