OldThink/Content.Shared/CombatMode/SharedCombatModeSystem.cs

using Robust.Shared.GameObjects;

namespace Content.Shared.CombatMode
{
    public abstract class SharedCombatModeSystem : EntitySystem
    {
        public override void Initialize()
        {
            base.Initialize();

            SubscribeNetworkEvent<CombatModeSystemMessages.SetCombatModeActiveMessage>(CombatModeActiveHandler);
            SubscribeLocalEvent<CombatModeSystemMessages.SetCombatModeActiveMessage>(CombatModeActiveHandler);
        }

        private void CombatModeActiveHandler(CombatModeSystemMessages.SetCombatModeActiveMessage ev, EntitySessionEventArgs eventArgs)
        {
            var entity = eventArgs.SenderSession.AttachedEntity;

            if (entity == default || !EntityManager.TryGetComponent(entity, out SharedCombatModeComponent? combatModeComponent))
            {
                return;
            }

            combatModeComponent.IsInCombatMode = ev.Active;
        }
    }
}