The battleground queue slots answer "none" from the first frame, so a party login no longer breaks BattlefieldFrame_Update (#603)

The reference's three queue slots are a static array (`0xb6e9d0`): `GetBattlefieldStatus(1..3)`
always reads one (`0x4ab4df`-`0x4ab4f3`), and a zeroed slot answers "none". The VM held an empty
list until the app's first push, so an in-range index took the off-slot leg and answered a nil
status. A party login fires PARTY_LEADER_CHANGED before that push, `BattlefieldFrame_Update` read
the nil status as queued and concatenated the nil map name (`BattlefieldFrame.lua:242`). The VM
now holds exactly three slots, zeroed until pushed, and the push takes three.

Verified: the new app test fires PARTY_LEADER_CHANGED on the stock BattlefieldFrame before any
push and failed with the reported error before the change; live, Probefive relogged into a stored
party raised the same error on the old build and none on this one (slot 1 reads "none", "Eastern
Kingdoms"), and a solo login after leaving the party is clean. Built on macOS only; no platform
seam.

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

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

@@ -13,7 +13,8 @@ use super::Model;
 pub struct BattlefieldQueueSlot {
     /// `+0x00`, the Map.dbc row id; 0 is a cleared slot, its name looked up like any other.
     pub map_id: u32,
-    /// The localized map name, or `None` when the id has no row (a real `nil`).
+    /// The localized map name, or `None` when the id has no row (a real `nil`). The VM holds no
+    /// Map.dbc, so a slot not yet pushed answers `nil` where the reference names row 0.
     pub map_name: Option<String>,
     /// `+0x04`: `0` none, `1` queued, `2` confirm, `3` active; anything else answers `"error"`.
     pub status: u32,
@@ -102,7 +103,7 @@ impl super::UiScript {
     /// clock getters move.
     pub fn set_battlefield_queue(
         &mut self,
-        slots: Vec<BattlefieldQueueSlot>,
+        slots: [BattlefieldQueueSlot; 3],
         instance_expiration_ms: u32,
     ) {
         let mut model = self.model_mut();
@@ -498,7 +499,7 @@ mod tests {
     #[test]
     fn get_battlefield_status_answers_five_values_on_every_leg() {
         let mut s = UiScript::new().unwrap();
-        s.set_battlefield_queue(vec![slot(489, 1, 5), slot(0, 0, 0), slot(529, 9, 2)], 0);
+        s.set_battlefield_queue([slot(489, 1, 5), slot(0, 0, 0), slot(529, 9, 2)], 0);
         let n = |s: &mut UiScript, i: &str| s.arity(&format!("GetBattlefieldStatus({i})")).unwrap();
         assert_eq!(n(&mut s, "1"), 5);
         assert_eq!(n(&mut s, "0"), 5);
@@ -532,7 +533,7 @@ mod tests {
         assert!(err.contains("Usage: GetBattlefieldStatus(index)"), "{err}");
         let mut empty = slot(0, 0, 0);
         empty.map_name = None;
-        s.set_battlefield_queue(vec![empty], 0);
+        s.set_battlefield_queue([empty, Default::default(), Default::default()], 0);
         assert!(
             s.eval::<bool>("local _, name = GetBattlefieldStatus(1) return name == nil")
                 .unwrap(),
@@ -540,10 +541,26 @@ mod tests {
         );
     }
 
+    #[test]
+    fn every_slot_answers_none_before_the_first_push() {
+        let s = UiScript::new().unwrap();
+        for i in 1..=3 {
+            assert_eq!(
+                s.eval::<String>(&format!("return (GetBattlefieldStatus({i}))"))
+                    .unwrap(),
+                "none",
+                "slot {i}"
+            );
+        }
+    }
+
     #[test]
     fn the_time_getters_read_the_pushed_milliseconds() {
         let mut s = UiScript::new().unwrap();
-        s.set_battlefield_queue(vec![slot(489, 1, 5)], 120_000);
+        s.set_battlefield_queue(
+            [slot(489, 1, 5), Default::default(), Default::default()],
+            120_000,
+        );
         assert_eq!(
             s.eval::<i64>("return GetBattlefieldPortExpiration(1)")
                 .unwrap(),
@@ -594,7 +611,7 @@ mod tests {
     #[test]
     fn show_battlefield_list_gates_on_a_queued_slot() {
         let mut s = UiScript::new().unwrap();
-        s.set_battlefield_queue(vec![slot(489, 1, 5), slot(529, 2, 1), slot(0, 1, 0)], 0);
+        s.set_battlefield_queue([slot(489, 1, 5), slot(529, 2, 1), slot(0, 1, 0)], 0);
         s.run("ShowBattlefieldList(1) ShowBattlefieldList(2) ShowBattlefieldList(3) ShowBattlefieldList(4)")
             .unwrap();
         assert_eq!(s.take_battlefield_list_requests(), vec![489]);

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

@@ -490,8 +490,10 @@ pub(crate) struct Model {
     pub(crate) battlefield_list: super::battlefield_queue::BattlefieldListView,
     /// The selected instance id (`[0xb6eba0]`), not an index; written by `SetSelectedBattlefield`.
     pub(crate) battlefield_selected: u32,
-    /// The three queue slots, pushed each frame with their clocks reduced to values.
-    pub(crate) battlefield_slots: Vec<super::battlefield_queue::BattlefieldQueueSlot>,
+    /// The three queue slots, pushed each frame with their clocks reduced to values. Zeroed
+    /// until the first push, as the reference's static slots (`0xb6e9d0`) are, so each answers
+    /// "none" from the first frame.
+    pub(crate) battlefield_slots: [super::battlefield_queue::BattlefieldQueueSlot; 3],
     /// `GetBattlefieldInstanceExpiration()`, pushed each frame.
     pub(crate) battlefield_instance_expiration_ms: u32,
     /// `JoinBattlefield` calls, `(instance id, as group)`.
@@ -1191,7 +1193,7 @@ impl Model {
             battlefield_leave_requests: 0,
             battlefield_list: Default::default(),
             battlefield_selected: 0,
-            battlefield_slots: Vec::new(),
+            battlefield_slots: Default::default(),
             battlefield_instance_expiration_ms: 0,
             battlefield_join_requests: Vec::new(),
             battlefield_list_requests: Vec::new(),