pub fn write_node(paths: &RunPaths, n: &Node) -> Result<()>Expand description
Atomically write a node’s projection file, keyed by its node_id.
Stays pub (unlike the other write_* helpers) as the sanctioned
lock-held composition path for the supervisor batch: the supervisor
mirrors per-child report cursors and a child’s supervisor_pid directly
onto the node projection while holding the run’s flock — fields no
event/reducer path manages. Pair it with crate::RunLock.