diff --git a/src/OpenApparatus.IO/Exporters/JsonExporter.cs b/src/OpenApparatus.IO/Exporters/JsonExporter.cs
index 164ea97..322e789 100644
--- a/src/OpenApparatus.IO/Exporters/JsonExporter.cs
+++ b/src/OpenApparatus.IO/Exporters/JsonExporter.cs
@@ -168,6 +168,10 @@ public static EnvironmentDocument BuildDocument(
                         Slot = o.Slot,
                         Position = new[] { o.Position.X, o.Position.Y, o.Position.Z },
                         Rotation = o.Rotation,
+                        GlobalId = o.GlobalId,
+                        TypeId = o.TypeId,
+                        CustomId = o.CustomId,
+                        Name = o.Name,
                     });
                 }
                 entry.Objects = objList;
@@ -193,6 +197,10 @@ public static EnvironmentDocument BuildDocument(
                     Slot = o.Slot,
                     Position = new[] { o.Position.X, o.Position.Y, o.Position.Z },
                     Rotation = o.Rotation,
+                    GlobalId = o.GlobalId,
+                    TypeId = o.TypeId,
+                    CustomId = o.CustomId,
+                    Name = o.Name,
                 });
             }
             if (outsideList != null)
@@ -360,6 +368,10 @@ public sealed class ObjectInstanceEntry
         public int Slot { get; set; }
         public float[] Position { get; set; } = System.Array.Empty<float>();
         public float Rotation { get; set; }
+        public string GlobalId { get; set; } = "";
+        public string TypeId { get; set; } = "";
+        public string CustomId { get; set; } = "";
+        public string Name { get; set; } = "";
     }
 
     public sealed class ShapeSection
diff --git a/src/OpenApparatus.IO/ProjectFile.cs b/src/OpenApparatus.IO/ProjectFile.cs
index 7182d76..2686386 100644
--- a/src/OpenApparatus.IO/ProjectFile.cs
+++ b/src/OpenApparatus.IO/ProjectFile.cs
@@ -109,4 +109,8 @@ public sealed class ObjectInstanceEntry
     public float Y { get; set; }
     public float Z { get; set; }
     public float Rotation { get; set; }
+    public string? GlobalId { get; set; }
+    public string? TypeId { get; set; }
+    public string? CustomId { get; set; }
+    public string? Name { get; set; }
 }
diff --git a/src/OpenApparatus.IO/RoomObject.cs b/src/OpenApparatus.IO/RoomObject.cs
index 07a3429..441dcf6 100644
--- a/src/OpenApparatus.IO/RoomObject.cs
+++ b/src/OpenApparatus.IO/RoomObject.cs
@@ -8,6 +8,11 @@ namespace OpenApparatus.IO;
 /// re-evaluated on Rebuild() so an object whose room shrinks or moves is
 /// reassigned to whatever room now contains its world position.
 /// <see cref="Slot"/> is a 1-based index into the VM's ObjectTypes list.
+///
+/// <see cref="GlobalId"/>, <see cref="TypeId"/>, <see cref="CustomId"/> and
+/// <see cref="Name"/> are user-editable identity strings. They get sensible
+/// defaults at placement time but uniqueness is not enforced — two objects
+/// may legitimately share any of them.
 /// </summary>
 public sealed class RoomObject
 {
@@ -15,6 +20,15 @@ public sealed class RoomObject
     public int Slot { get; set; }
     public Vector3 Position { get; set; }
     public float Rotation { get; set; }
+
+    /// <summary>Per-apparatus running index, assigned at placement (0, 1, 2…).</summary>
+    public string GlobalId { get; set; } = "";
+    /// <summary>Per-type running index, assigned at placement (0, 1, 2… within the object's type).</summary>
+    public string TypeId { get; set; } = "";
+    /// <summary>Free-form identifier; defaults to "{GlobalId}_{TypeId}".</summary>
+    public string CustomId { get; set; } = "";
+    /// <summary>Display name; defaults to "{TypeName}_{GlobalId}_{TypeId}".</summary>
+    public string Name { get; set; } = "";
 }
 
 /// <summary>Shape primitive for object types. Procedural geometry is generated