command

Command shape widened to the v1 surface + protocol-v2 additions.

• resume — dispatches to thread.input.respond targeting the most recent root-namespace interrupt (honoured today).
• goto — routes execution to a specific node (planned, forwarded via /run.start metadata).
• update — merges a partial state update into the thread's values before resuming (planned, forwarded via /run.start).

Only resume is currently executed by the controller; goto / update are accepted by the type surface so callers can migrate without breakage once the server work lands (plan-roadmap.md §5.3 R2.4).