diff --git a/tests/test_item_id.rs b/tests/test_item_id.rs
new file mode 100644
index 0000000..dfe8b7b
--- /dev/null
+++ b/tests/test_item_id.rs
@@ -0,0 +1,298 @@
+use elseware::common::serverstate::{ClientId, ServerState};
+use elseware::entity::gateway::{EntityGateway, InMemoryGateway};
+use elseware::entity::item;
+use elseware::ship::ship::{ShipServerState, RecvShipPacket};
+use elseware::entity::character::TechLevel;
+//use elseware::ship::items::{ClientItemId, ActiveItemEntityId, HeldItemType, FloorItemType};
+
+use libpso::packet::ship::*;
+use libpso::packet::messages::*;
+
+#[path = "common.rs"]
+mod common;
+use common::*;
+
+
+#[async_std::test]
+async fn test_use_monomate_after_leaving_and_rejoining_room() {
+    let mut entity_gateway = InMemoryGateway::default();
+    let (_user1, char1) = new_user_character(&mut entity_gateway, "a1", "a", 1).await;
+    let (_user2, char2) = new_user_character(&mut entity_gateway, "a2", "a", 1).await;
+
+    let mut p1_items = Vec::new();
+    for tool in vec![item::tool::ToolType::Monomate, item::tool::ToolType::Monofluid].into_iter() {
+        let mut item = Vec::new();
+        for _ in 0..2usize {
+            item.push(entity_gateway.create_item(
+                item::NewItemEntity {
+                    item: item::ItemDetail::Tool(
+                        item::tool::Tool {
+                            tool: tool
+                        }
+                    ),
+                }).await.unwrap());
+        }
+        p1_items.push(item::InventoryItemEntity::Stacked(item));
+    }
+
+    entity_gateway.set_character_inventory(&char1.id, &item::InventoryEntity::new(p1_items)).await.unwrap();
+
+    let mut p2_items = Vec::new();
+    for tool in vec![item::tool::ToolType::Monomate, item::tool::ToolType::Monofluid].into_iter() {
+        let mut item = Vec::new();
+        for _ in 0..2usize {
+            item.push(entity_gateway.create_item(
+                item::NewItemEntity {
+                    item: item::ItemDetail::Tool(
+                        item::tool::Tool {
+                            tool: tool
+                        }
+                    ),
+                }).await.unwrap());
+        }
+        p2_items.push(item::InventoryItemEntity::Stacked(item));
+    }
+
+    entity_gateway.set_character_inventory(&char2.id, &item::InventoryEntity::new(p2_items)).await.unwrap();
+
+    let mut ship = Box::new(ShipServerState::builder()
+        .gateway(entity_gateway.clone())
+        .build());
+    log_in_char(&mut ship, ClientId(1), "a1", "a").await;
+    log_in_char(&mut ship, ClientId(2), "a2", "a").await;
+    join_lobby(&mut ship, ClientId(1)).await;
+    join_lobby(&mut ship, ClientId(2)).await;
+    create_room(&mut ship, ClientId(1), "room", "").await;
+
+    join_room(&mut ship, ClientId(2), 0).await;
+    leave_room(&mut ship, ClientId(2)).await;
+    join_room(&mut ship, ClientId(2), 0).await;
+    leave_room(&mut ship, ClientId(2)).await;
+    join_room(&mut ship, ClientId(2), 0).await;
+    leave_room(&mut ship, ClientId(2)).await;
+    join_room(&mut ship, ClientId(2), 0).await;
+
+    leave_room(&mut ship, ClientId(1)).await;
+    join_room(&mut ship, ClientId(1), 0).await;
+
+    ship.handle(ClientId(1), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x10003,
+    })))).await.unwrap();
+
+    ship.handle(ClientId(2), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x210006,
+    })))).await.unwrap();
+
+    let inventory_items = entity_gateway.get_character_inventory(&char1.id).await.unwrap();
+    assert_eq!(inventory_items.items.len(), 2);
+    inventory_items.items[0].with_stacked(|items| {
+        assert_eq!(items.len(), 2)
+    }).unwrap();
+    inventory_items.items[1].with_stacked(|items| {
+        assert_eq!(items.len(), 1)
+    }).unwrap();
+
+    let inventory_items = entity_gateway.get_character_inventory(&char2.id).await.unwrap();
+    assert_eq!(inventory_items.items.len(), 2);
+    inventory_items.items[0].with_stacked(|items| {
+        assert_eq!(items.len(), 1)
+    }).unwrap();
+    inventory_items.items[1].with_stacked(|items| {
+        assert_eq!(items.len(), 2)
+    }).unwrap();
+}
+
+
+
+#[async_std::test]
+async fn test_using_some_monomates_after_a_convoluted_series_of_leaves_and_joins() {
+    let mut entity_gateway = InMemoryGateway::default();
+    let (_user1, char1) = new_user_character(&mut entity_gateway, "a1", "a", 1).await;
+    let (_user2, char2) = new_user_character(&mut entity_gateway, "a2", "a", 1).await;
+    let (_user3, char3) = new_user_character(&mut entity_gateway, "a3", "a", 1).await;
+
+    let mut p1_items = Vec::new();
+    for tool in vec![item::tool::ToolType::Monofluid, item::tool::ToolType::Difluid, item::tool::ToolType::Trifluid].into_iter() {
+        let mut item = Vec::new();
+        for _ in 0..2usize {
+            item.push(entity_gateway.create_item(
+                item::NewItemEntity {
+                    item: item::ItemDetail::Tool(
+                        item::tool::Tool {
+                            tool: tool
+                        }
+                    ),
+                }).await.unwrap());
+        }
+        p1_items.push(item::InventoryItemEntity::Stacked(item));
+    }
+    entity_gateway.set_character_inventory(&char1.id, &item::InventoryEntity::new(p1_items)).await.unwrap();
+
+    let mut p2_items = Vec::new();
+    for tool in vec![item::tool::ToolType::Monomate, item::tool::ToolType::Monofluid].into_iter() {
+        let mut item = Vec::new();
+        for _ in 0..6usize {
+            item.push(entity_gateway.create_item(
+                item::NewItemEntity {
+                    item: item::ItemDetail::Tool(
+                        item::tool::Tool {
+                            tool: tool
+                        }
+                    ),
+                }).await.unwrap());
+        }
+        p2_items.push(item::InventoryItemEntity::Stacked(item));
+    }
+    entity_gateway.set_character_inventory(&char2.id, &item::InventoryEntity::new(p2_items)).await.unwrap();
+
+    let mut p3_items = Vec::new();
+    for _ in 0..5usize {
+        p3_items.push(
+            item::InventoryItemEntity::Individual(
+                entity_gateway.create_item(
+                    item::NewItemEntity {
+                        item: item::ItemDetail::Weapon(
+                            item::weapon::Weapon {
+                            weapon: item::weapon::WeaponType::Saber,
+                            grind: 0,
+                            special: None,
+                            attrs: [None, None, None],
+                            tekked: true,
+                            }
+                        ),
+                    }).await.unwrap()
+            ));
+    }
+    entity_gateway.set_character_inventory(&char3.id, &item::InventoryEntity::new(p3_items)).await.unwrap();
+
+    let mut ship = Box::new(ShipServerState::builder()
+        .gateway(entity_gateway.clone())
+        .build());
+    log_in_char(&mut ship, ClientId(1), "a1", "a").await;
+    log_in_char(&mut ship, ClientId(2), "a2", "a").await;
+    log_in_char(&mut ship, ClientId(3), "a3", "a").await;
+    join_lobby(&mut ship, ClientId(1)).await;
+    join_lobby(&mut ship, ClientId(2)).await;
+    join_lobby(&mut ship, ClientId(3)).await;
+
+    // so lets trace the item_ids here as it is dumb:
+    create_room(&mut ship, ClientId(1), "room", "").await;
+    // g1/p1: 0x010000 0x010001 0x010002 ; 0x010003
+    // g2  :                             ; 0x210000
+    // g3  :                             ; 0x410000
+
+    join_room(&mut ship, ClientId(2), 0).await;
+    // g1/p1: 0x010000 0x010001 0x010002 ; 0x10003
+    // g2/p2: 0x210000 0x210001          ; 0x210002
+    // g3   :                            ; 0x410000
+
+    ship.handle(ClientId(2), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x210000,
+    })))).await.unwrap();
+
+    join_room(&mut ship, ClientId(3), 0).await;
+    // g1/p1: 0x010000 0x010001 0x010002                    ; 0x010003
+    // g2/p2: 0x210000 0x210001                             ; 0x210002
+    // g3/p3: 0x410000 0x410001 0x410002 0x410003 0x0410004 ; 0x410005
+
+    leave_room(&mut ship, ClientId(2)).await;
+    // g1/p1: 0x010000 0x010001 0x010002                    ; 0x010003
+    // g2   :                                               ; 0x210002
+    // g3/p3: 0x410000 0x410001 0x410002 0x410003 0x410004  ; 0x410005
+
+    join_room(&mut ship, ClientId(2), 0).await;
+    // g1/p1: 0x010000 0x010001 0x010002                    ; 0x010003
+    // g2/p2: 0x210002 0x210003                             ; 0x210004
+    // g3/p3: 0x410000 0x410001 0x410002 0x410003 0x410004  ; 0x410005
+
+    leave_room(&mut ship, ClientId(2)).await;
+    // g1/p1: 0x010000 0x010001 0x010002                    ; 0x010003
+    // g2   :                                               ; 0x210004
+    // g3/p3: 0x410000 0x410001 0x410002 0x410003 0x410004  ; 0x410005
+    
+    leave_room(&mut ship, ClientId(3)).await;
+    // g1/p1: 0x010000 0x010001 0x010002                     ; 0x010003
+    // g2   :                                                ; 0x210004
+    // g3   :                                                ; 0x410005
+
+    join_room(&mut ship, ClientId(3), 0).await;
+    // g1/p1: 0x010000 0x010001 0x010002                   ; 0x010003
+    // g2/p3: 0x210004 0x210005 0x210006 0x210007 0x210008 ; 0x210009
+    // g3   :                                              ; 0x410007
+
+    join_room(&mut ship, ClientId(2), 0).await;
+    // g1/p1: 0x010000 0x010001 0x010002                   ; 0x010003
+    // g2/p3: 0x210004 0x210005 0x210006 0x210007 0x210008 ; 0x210009
+    // g3/p2: 0x410005 0x410006                            ; 0x410007
+
+    ship.handle(ClientId(2), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x410005,
+    })))).await.unwrap();
+
+    leave_room(&mut ship, ClientId(1)).await;
+    leave_room(&mut ship, ClientId(2)).await;
+    // g1  :                                               ; 0x010003
+    // g2/p3: 0x210004 0x210005 0x210006 0x210007 0x210008 ; 0x210009
+    // g3   :                                              ; 0x410007
+
+    join_room(&mut ship, ClientId(2), 0).await;
+    // g1/p2: 0x010003 0x010004                            ; 0x010005
+    // g2/p3: 0x210004 0x210005 0x210006 0x210007 0x210008 ; 0x210009
+    // g3   :                                              ; 0x410007
+
+    join_room(&mut ship, ClientId(1), 0).await;
+    // g1/p2: 0x010003 0x010004                            ; 0x010005
+    // g2/p3: 0x210004 0x210005 0x210006 0x210007 0x210008 ; 0x210009
+    // g3/p1: 0x410008 0x410009 0x41000A                   ; 0x41000B
+
+    ship.handle(ClientId(2), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x010003,
+    })))).await.unwrap();
+
+    leave_room(&mut ship, ClientId(2)).await;
+    leave_room(&mut ship, ClientId(3)).await;
+    join_room(&mut ship, ClientId(3), 0).await;
+    join_room(&mut ship, ClientId(2), 0).await;
+    // g1/p3: 0x010005 0x010006 0x010007 0x010008 0x010009 ; 0x010009
+    // g2/p2: 0x210009 0x21000A                            ; 0x21000B
+    // g3/p1: 0x410008 0x410009 0x41000A                   ; 0x41000B
+
+    ship.handle(ClientId(2), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x210009,
+    })))).await.unwrap();
+
+    leave_room(&mut ship, ClientId(2)).await;
+    join_room(&mut ship, ClientId(2), 0).await;
+    // g1/p3: 0x010005 0x010006 0x010007 0x010008 0x010009 ; 0x010009
+    // g2/p2: 0x21000B 0x21000C                          ; 0x21000D
+    // g3/p1: 0x410008 0x410009 0x401000A                ; 0x41000B
+
+    ship.handle(ClientId(2), RecvShipPacket::Message(Message::new(GameMessage::PlayerUseItem(PlayerUseItem {
+        client: 0,
+        target: 0,
+        item_id: 0x21000B,
+    })))).await.unwrap();
+
+
+    let inventory_items = entity_gateway.get_character_inventory(&char2.id).await.unwrap();
+    assert_eq!(inventory_items.items.len(), 2);
+    inventory_items.items[0].with_stacked(|items| {
+        assert_eq!(items.len(), 1)
+    }).unwrap();
+    inventory_items.items[1].with_stacked(|items| {
+        assert_eq!(items.len(), 6)
+    }).unwrap();
+}
+