Background Aggregated Runtime

1mcp serve --background starts a detached Background Aggregated Runtime for the selected Runtime Scope, while 1mcp serve --status and 1mcp serve --stop own lifecycle inspection and shutdown. Runtime uniqueness is scoped to the configuration directory: the default config directory behaves as the global runtime, and an explicit alternate --config-dir may run its own instance. Client surfaces such as proxy, inspect, and run remain attach-only rather than implicitly starting or stopping runtimes.

Background runtimes are HTTP-only because lifecycle discovery, readiness, and PID-file status all depend on an HTTP runtime URL; stdio cannot be detached safely because the protocol uses the invoking process stdin/stdout.