teraWeb/backend/internal/serial/connection_status.go

package serial

import "time"

// Allow several normal four-second sweeps to recover from a slow/noisy reply.
// A CR timeout alone cannot establish physical cable disconnection.
const CRResponseGracePeriod = 15 * time.Second

func CRConnectionStatus(probe CRProbeState, now time.Time) string {
	if !probe.Enabled {
		return "unknown"
	}
	if probe.Up {
		return "up"
	}
	if probe.EverUp && probe.LastResponseAt != nil {
		age := now.Sub(*probe.LastResponseAt)
		if age >= 0 && age <= CRResponseGracePeriod {
			return "up"
		}
	}
	return "unknown"
}