Layers: one owner puts orbitals above the ship plane and floaters below; per-hull GridOffset is deleted

GameplaySettings carries ShipLayerHeight 3, OrbitalLayerHeight 15, FloaterLayerHeight 0 (authored in Settings.asset).
Entity.LayerHeight (Ship, OrbitalEntity) is the one offset RideHeight adds; DrawAhead.FloaterHeight is the floater
height ItemPickup and MineInstance draw at. HullData.GridOffset (Key 26) and the pickup/mine/prefab GridOffset fields
are gone with every reader. Fixtures (DrawnPose, FireControl*, ImpactFeedback) take heights from the layer owner;
LayerTests pin each kind's layer. FloatingItemsDrawnSmoke follows. ItemPickup/MineInstance.Bind take the settings from
ZoneRenderer. Builds as one commit with its tests; not compile-verified until the cut's head run.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assets/Scripts/ServerShared/DrawAhead.cs

@@ -26,6 +26,9 @@ public static class DrawAhead
     // The field's height at a point at the drawn time, its wells where their rails put them at T.
     public static float Height(Zone zone, float2 planar, float lead) => zone.GetHeight(planar, Time(zone, lead));
 
+    // The drawn height of a floater (loot, mines): the field at the drawn time plus the floater layer.
+    public static float FloaterHeight(Zone zone, GameplaySettings settings, float2 planar, float lead) => Height(zone, planar, lead) + settings.FloaterLayerHeight;
+
     // A ship in a wormhole animation has its pose scripted by the step, not integrated from Velocity and TurnRate,
     // so it is drawn where the step put it: extrapolating a scripted pose draws a streak that resets every step.
     // A child is drawn where its parent is drawn, as the step copies the parent's pose onto it.

Assets/Scripts/ServerShared/Entity.cs

@@ -1974,9 +1974,13 @@ public abstract class Entity
         Manoeuvre.Observe(Acceleration, delta, ItemManager.GameplaySettings.SolutionWindow);
     }
 
-    // Where an unparented entity sits on the field at a planar point: the zone's height there plus the hull's grid offset.
-    // The step rides at its own time and xz, the presenter at the drawn time and its drawn xz (DrawAhead).
-    public float RideHeight(float2 planar, double time) => Zone.GetHeight(planar, time) + (ItemManager.GetData(Hull) as HullData).GridOffset;
+    // The height above the field of the layer this kind of entity rides on (GameplaySettings): ships the ship plane,
+    // orbital entities the orbital layer above it.
+    public abstract float LayerHeight { get; }
+
+    // Where an unparented entity sits on the field at a planar point: the zone's height there plus the layer this kind of
+    // entity rides on. The step rides at its own time and xz, the presenter at the drawn time and its drawn xz (DrawAhead).
+    public float RideHeight(float2 planar, double time) => Zone.GetHeight(planar, time) + LayerHeight;
 
     public float RideHeight(float2 planar) => RideHeight(planar, Zone.ExactTime);
 

Assets/Scripts/ServerShared/ItemData.cs

@@ -519,8 +519,7 @@ public class HullData : EquippableItemData
     [Inspectable, JsonProperty("hullType"), Key(25)]
     public HullType HullType;
 
-    [Inspectable, JsonProperty("gridOffset"), Key(26)]
-    public float GridOffset;
+    // Key(26) retired 2026-10-16 (per-hull GridOffset; the layer is the kind's, GameplaySettings). Do not reuse.
 
     [Inspectable, JsonProperty("armor"), Key(27)]
     public float Armor;

Assets/Scripts/ServerShared/OrbitalEntity.cs

@@ -23,6 +23,8 @@ public class OrbitalEntity : Entity
         OrbitData = orbit;
     }
 
+    public override float LayerHeight => ItemManager.GameplaySettings.OrbitalLayerHeight;
+
     public override void Update(float delta)
     {
         if (OrbitData.IsSet())

Assets/Scripts/ServerShared/Settings.cs

@@ -278,6 +278,13 @@ public class GameplaySettings
     // normal is this times the speed at which it closed. 0 is perfectly inelastic, 1 perfectly elastic.
     public float ContactRestitution = .5f;
 
+    // Heights above the field of the ship plane, the orbital layer (stations, turrets: every OrbitalEntity) and the floater
+    // layer (loot, mines): orbitals above ships and floaters below them, so no ship ever touches either (ruling
+    // aetheria-gravity:orbitals-above-floaters-below).
+    public float ShipLayerHeight = 3f;
+    public float OrbitalLayerHeight = 15f;
+    public float FloaterLayerHeight = 0f;
+
     // The floor an AI's own predicted hit probability (FireControl.HitProbability) must clear before it counts
     // a firing solution worth taking (Combat.cs, TurretController.cs). Player fire is gated on arc alone
     // (Weapon.ArcAllowsFire, Q2) -- this threshold is an AI fire-discipline heuristic, not part of the roll.

Assets/Scripts/ServerShared/Ship.cs

@@ -16,6 +16,8 @@ using quaternion = CultMath.quaternion;
 [MessagePackObject]
 public class Ship : Entity
 {
+    public override float LayerHeight => ItemManager.GameplaySettings.ShipLayerHeight;
+
     
     // [Key("bindings")]   public Dictionary<KeyCode,Guid>    Bindings = new Dictionary<KeyCode,Guid>();
     //[IgnoreMember] public int HullHardpointCount;