Function exec_command 

pub fn exec_command(
    id: &ContainerId,
    program: &str,
    args: &[String],
    cwd: &Path,
) -> Command

A docker exec -i command channel for one in-container program: piped stdin/stdout/stderr, working directory inside the container. The caller owns process supervision (group, kill-on-drop) as with every strop process launch. The id is the canonical inspect id — incarnation pinning is the read path’s concern; a spawned session’s liveness is scoped to itself.