SessionProcess

Starts and manages a long-lived Claude Code CLI session process.

The process is spawned once and kept alive for the whole session. stdin is fed from a queue (keeping the pipe open across sends). ONE internal reader fiber owns the stdout stream: it parses each line, captures the session id, routes control responses to their waiting request, folds results into the readable SessionState, and fans every message out over a Hub — so any number of events/stateChanges consumers each see the full stream. Scope finalizers close stdin and kill the process on exit.