some backend stuff for air alarms

finally, some UI states!!!

Content.Shared/Atmos/Monitor/AtmosSensorData.cs

@@ -0,0 +1,37 @@
+using Content.Shared.Atmos.Monitor.Components;
+
+namespace Content.Shared.Atmos.Monitor;
+
+public sealed class AtmosSensorData : IAtmosDeviceData
+{
+    public bool Enabled { get; set; }
+    public bool Dirty { get; set; }
+    public bool IgnoreAlarms { get; set; }
+
+    /// Most fields are readonly, because it's data that's meant to be transmitted.
+
+    /// <summary>
+    ///     Current pressure detected by this sensor.
+    /// </summary>
+    public float? Pressure { get; }
+    /// <summary>
+    ///     Current temperature detected by this sensor.
+    /// </summary>
+    public float? Temperature { get; }
+    /// <summary>
+    ///     Current amount of moles detected by this sensor.
+    /// </summary>
+    public float? TotalMoles { get; }
+    /// <summary>
+    ///     Current alarm state of this sensor. Does not reflect the highest alarm state on the network.
+    /// </summary>
+    public AtmosMonitorAlarmType AlarmState { get; }
+    /// <summary>
+    ///     Current number of gases on this sensor.
+    /// </summary>
+    public Dictionary<Gas, float> Gases { get; }
+    /// <summary>
+    ///     If this sensor is currently detecting a fire.
+    /// </summary>
+    public bool OnFire { get; }
+}

Content.Shared/Atmos/Monitor/Components/SharedAirAlarmComponent.cs

@@ -55,11 +55,34 @@ namespace Content.Shared.Atmos.Monitor.Components
         public bool IgnoreAlarms { get; set; }
     }
 
-    // would be nice to include the entire state here
-    // but it's already handled by messages
     [Serializable, NetSerializable]
     public sealed class AirAlarmUIState : BoundUserInterfaceState
-    {}
+    {
+        public AirAlarmUIState(Dictionary<string, IAtmosDeviceData> deviceData, AirAlarmMode mode, AirAlarmTab tab, AtmosMonitorAlarmType alarmType)
+        {
+            DeviceData = deviceData;
+            Mode = mode;
+            Tab = tab;
+            AlarmType = alarmType;
+        }
+
+        /// <summary>
+        ///     Every single device data that can be seen from this
+        ///     air alarm. This includes vents, scrubbers, and sensors.
+        ///     The device data you get, however, depends on the current
+        ///     selected tab.
+        /// </summary>
+        public Dictionary<string, IAtmosDeviceData> DeviceData { get; }
+        public AirAlarmMode Mode { get; }
+        public AirAlarmTab Tab { get; }
+        public AtmosMonitorAlarmType AlarmType { get; }
+    }
+
+    [Serializable, NetSerializable]
+    public sealed class AirAlarmTabSetMessage : BoundUserInterfaceMessage
+    {
+        public AirAlarmTab Tab { get; }
+    }
 
     [Serializable, NetSerializable]
     public sealed class AirAlarmResyncAllDevicesMessage : BoundUserInterfaceMessage
@@ -126,5 +149,11 @@ namespace Content.Shared.Atmos.Monitor.Components
         }
     }
 
-
+    public enum AirAlarmTab
+    {
+        Vent,
+        Scrubber,
+        Sensors,
+        Settings
+    }
 }