ClearCursor signals CURSOR_UPDATE on every call, an empty cursor included, as 1.12.1's shared tail does (#432)

Fixes #425

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

crates/benilla-ui/src/script/cursor.rs

@@ -223,8 +223,8 @@ pub(super) fn item_link_name(link: Option<&str>) -> String {
         .unwrap_or_default()
 }
 
-/// `ClearCursor()`: drops any payload and frees an item's source slot; an empty cursor fires
-/// nothing.
+/// `ClearCursor()` (`0x495190`): drops any payload and frees an item's source slot, then signals
+/// `CURSOR_UPDATE` from its shared tail (`0x49529b`) on every call, an empty cursor included.
 pub(crate) fn clear_cursor(model: &mut Model) {
     // Any clear first cancels an armed gift wrap, whatever its parameters (`0x495190` opens with
     // `0x5edf10`): the wrapping paper unlocks and the cursor mode returns to the base.
@@ -233,25 +233,12 @@ pub(crate) fn clear_cursor(model: &mut Model) {
         model.ui_cursor = None;
         model.ui_cursor_dirty = true;
     }
-    match model.cursor.take() {
-        Some(CursorPayload::Item(item)) => {
-            queue_cursor_update(model);
-            queue_lock_changed(model, item.bag, item.slot);
-        }
-        Some(
-            CursorPayload::Spell(_)
-            | CursorPayload::Action(_)
-            | CursorPayload::Macro(_)
-            | CursorPayload::PetAction(_)
-            | CursorPayload::StablePet(_)
-            // Coins: the purse was never debited, so nothing goes back.
-            | CursorPayload::Money(_)
-            // A vendor row clears with no packet (`0x49525f`).
-            | CursorPayload::Merchant(_),
-        ) => {
-            queue_cursor_update(model);
-        }
-        None => {}
+    // Coins go back to nothing, as the purse was never debited; a vendor row clears with no
+    // packet (`0x49525f`).
+    let taken = model.cursor.take();
+    queue_cursor_update(model);
+    if let Some(CursorPayload::Item(item)) = taken {
+        queue_lock_changed(model, item.bag, item.slot);
     }
 }
 
@@ -742,6 +729,20 @@ mod tests {
         assert!(s.cursor_payload().is_none());
     }
 
+    /// The clear's shared tail (`0x49529b`) signals on every call: with nothing held, one
+    /// `CURSOR_UPDATE` and no grid event.
+    #[test]
+    fn clear_cursor_with_nothing_held_still_signals() {
+        let s = UiScript::new().unwrap();
+        let before = s.model_ref().pending_events.len();
+        s.run("ClearCursor()").unwrap();
+        let fired: Vec<String> = s.model_ref().pending_events[before..]
+            .iter()
+            .map(|(e, _)| e.clone())
+            .collect();
+        assert_eq!(fired, vec!["CURSOR_UPDATE"]);
+    }
+
     /// Clearing a spell on terrain is the deviation documented on `world_drop_click`.
     #[test]
     fn world_drop_terrain_and_nothing_both_clear_a_spell_payload() {

crates/benilla-ui/src/script/cursor/bag_verbs.rs

@@ -142,15 +142,18 @@ pub(super) fn put_item_in_backpack(model: &mut Model) -> bool {
     true
 }
 
-/// `PickupBagFromSlot(inventorySlot)` (`0x4c7b00`): clears the cursor before it looks at the slot,
-/// where the reference clears only a held item (`0x4c7b70`, `0x4c7b79`); takes only a container
+/// `PickupBagFromSlot(inventorySlot)` (`0x4c7b00`): clears a held payload before it looks at the
+/// slot, where the reference clears only a held item (`0x4c7b70`, `0x4c7b79`); with nothing held it
+/// skips the clear and its `CURSOR_UPDATE`, as the reference does. Takes only a container
 /// (`0x4c7bb3`), and never places or swaps. The client has no empty-bag rule: the server refuses
 /// with `EQUIP_ERR_CAN_ONLY_DO_WITH_EMPTY_BAGS`.
 pub(super) fn pickup_bag_from_slot(model: &mut Model, live: u32) {
     if !accepts(live) {
         return;
     }
-    clear_cursor(model);
+    if model.cursor.is_some() {
+        clear_cursor(model);
+    }
     let picked = usize::try_from(live)
         .ok()
         .and_then(|slot| model.inv_slot("player", slot))
@@ -227,6 +230,17 @@ mod tests {
         InventorySlots, UiScript,
     };
 
+    /// With nothing held the reference skips the clear (`0x4c7b6a`-`0x4c7b70`), so a drag from an
+    /// empty bag slot signals nothing.
+    #[test]
+    fn an_empty_cursor_skips_the_clear_and_its_signal() {
+        let s = UiScript::new().unwrap();
+        let before = s.model_ref().pending_events.len();
+        s.run("PickupBagFromSlot(20)").unwrap();
+        assert!(s.cursor_payload().is_none());
+        assert_eq!(s.model_ref().pending_events.len(), before);
+    }
+
     /// An item that is a bag: `equip_slots` is `find_equip_slot(INVTYPE_BAG)`.
     fn bag_slot_view(item_id: u32) -> InvSlotView {
         InvSlotView {

crates/benilla-ui/src/script/merchant.rs

@@ -1114,8 +1114,9 @@ mod tests {
         (n("updates"), n("shows"), n("hides"))
     }
 
-    /// The grab goes through the cursor setter (`0x4950f0`): `CURSOR_UPDATE` at `0x495159`, and
-    /// no `ACTIONBAR_SHOWGRID` since mode 5 is not mode 7.
+    /// The grab goes through the cursor setter (`0x4950f0`): its `ClearCursor(1,1)` (`0x495112`)
+    /// signals `CURSOR_UPDATE` from the clear's tail, the set signals it again (`0x495159`), and no
+    /// `ACTIONBAR_SHOWGRID` since mode 5 is not mode 7.
     #[test]
     fn a_vendor_grab_fires_cursor_update_but_not_the_bar_grid() {
         let mut s = UiScript::new().unwrap();
@@ -1124,12 +1125,12 @@ mod tests {
         s.run("PickupMerchantItem(1)").unwrap();
         assert_eq!(
             cursor_event_counts(&mut s),
-            (1, 0, 0),
+            (2, 0, 0),
             "(CURSOR_UPDATE, ACTIONBAR_SHOWGRID, ACTIONBAR_HIDEGRID) after a vendor grab"
         );
         // The toggle-off is a plain clear: one more CURSOR_UPDATE, no HIDEGRID.
         s.run("PickupMerchantItem(1)").unwrap();
-        assert_eq!(cursor_event_counts(&mut s), (2, 0, 0));
+        assert_eq!(cursor_event_counts(&mut s), (3, 0, 0));
     }
 
     #[test]