From a8c57c28bc221f1e4feebbb1660e82ba52f9dd88 Mon Sep 17 00:00:00 2001
From: Krathe <Krathe82@users.noreply.github.com>
Date: Mon, 8 Jun 2026 22:54:13 +0100
Subject: [PATCH] Sorting: stable tiebreak so group frames don't reshuffle
 mid-M+
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The sort comparators ended with `return false` for equal-key members (same role
with Alphabetical off, or tied names), and Lua's table.sort is not stable. A
roster-driven re-sort during an encounter (pet summon/dismiss, role/assist churn
-> GROUP_ROSTER_UPDATE) could then land same-role players in a different order,
changing the rebuilt nameList so the secure header reorders the frames — the
"group frames rearrange mid-M+ after pulls" report.

Add a deterministic final tiebreak by name (invariant per session, realm-
qualified in the nameList) so every re-sort of the same roster yields an
identical order:
- Headers.lua SortMembers — the live nameList path; covers the player too, which
  is re-sorted through the same comparator in SORTED mode.
- Sort.lua CompareUnits + CompareTestData — legacy/test path, same pattern.

Trade-off: with Alphabetical off, members of the same role now order by name
(previously undefined/shuffling) rather than an arbitrary order.
---
 Features/Sort.lua  | 15 +++++++++++++--
 Frames/Headers.lua | 12 +++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/Features/Sort.lua b/Features/Sort.lua
index bd4a2300..8f547ef6 100644
--- a/Features/Sort.lua
+++ b/Features/Sort.lua
@@ -194,7 +194,13 @@ function Sort:CompareUnits(unitA, unitB, db)
             return nameA < nameB
         end
     end
-    
+
+    -- Deterministic final tiebreak: equal-key units need a stable order, or the
+    -- unstable Lua table.sort reshuffles them on each re-sort (group-frame shuffle
+    -- during M+ pulls). Mirrors Headers.lua SortMembers.
+    local tieA = UnitName(unitA) or ""
+    local tieB = UnitName(unitB) or ""
+    if tieA ~= tieB then return tieA < tieB end
     return false
 end
 
@@ -267,7 +273,12 @@ function Sort:CompareTestData(dataA, dataB, db)
             return nameA < nameB
         end
     end
-    
+
+    -- Deterministic final tiebreak (see CompareUnits) so test-mode sorting is
+    -- stable across re-sorts too.
+    local tieA = dataA.name or ""
+    local tieB = dataB.name or ""
+    if tieA ~= tieB then return tieA < tieB end
     return false
 end
 
diff --git a/Frames/Headers.lua b/Frames/Headers.lua
index ab501355..4a007753 100755
--- a/Frames/Headers.lua
+++ b/Frames/Headers.lua
@@ -4878,9 +4878,19 @@ function DF:BuildSortedNameList(members, db, selfPosition, includesPlayer)
                 return a.name < b.name
             end
         end
+        -- Deterministic final tiebreak. Without one, members with equal sort keys
+        -- (same role, Alphabetical off) have no defined order, and Lua's table.sort
+        -- is NOT stable — so a roster-driven re-sort mid-encounter reshuffles
+        -- same-role players, making the group frames rearrange during M+ pulls.
+        -- Break ties by name (invariant for the session, and realm-qualified in the
+        -- nameList so cross-realm names don't collide) so every re-sort of the same
+        -- roster produces an identical order and the secure header never reorders.
+        if a.name ~= b.name then
+            return a.name < b.name
+        end
         return false
     end
-    
+
     -- Sort non-player members
     table.sort(sortedMembers, SortMembers)