// Package useridentity owns side-effect-free persisted-user identity helpers.
package useridentity

import "strings"

// DisplayName composes the stable user label used by live and rebuilt sessions.
func DisplayName(username, firstName, lastName string) string {
	parts := make([]string, 0, 2)
	if firstName != "" {
		parts = append(parts, firstName)
	}
	if lastName != "" {
		parts = append(parts, lastName)
	}
	if len(parts) != 0 {
		return strings.Join(parts, " ")
	}
	return username
}