//! Metrics collection (reserved).
//!
//! Placeholder for OpenTelemetry metric registration and recording
//! helpers backing [`super::custom_metrics::MpiMetrics`](crate::observability::custom_metrics::MpiMetrics). Note the
//! crate also exposes a separate Prometheus text-exposition surface in
//! [`crate::metrics`]; this module is the OTLP counterpart and will be
//! filled in when the OTLP pipeline lands.
// OpenTelemetry metrics implementation