From db54e5ae1c2412d3e20405da29017fa43fa71f1f Mon Sep 17 00:00:00 2001
From: Kurt <kwsch@users.noreply.github.com>
Date: Sat, 17 Jan 2026 16:14:09 -0600
Subject: [PATCH] Fix identity swap when using span slices

Closes #684

Defensively allocate a copy so that the replacement does not overwrite the original sequence A=>B then continue doing B=>B swaps.
Wasn't a problem before since properties fetched byte[] (allocated separate slice); changing to span introduced this regression -- now fixed.
---
 NHSE.Core/Save/Meta/HorizonSave.cs               | 1 +
 NHSE.Core/Structures/Villager/IVillagerOrigin.cs | 4 ++--
 NHSE.WinForms/Editor.cs                          | 4 ++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/NHSE.Core/Save/Meta/HorizonSave.cs b/NHSE.Core/Save/Meta/HorizonSave.cs
index 526d488..1719c88 100644
--- a/NHSE.Core/Save/Meta/HorizonSave.cs
+++ b/NHSE.Core/Save/Meta/HorizonSave.cs
@@ -77,6 +77,7 @@ public IEnumerable<FileHashRegion> GetInvalidHashes()
 
     public void ChangeIdentity(ReadOnlySpan<byte> original, ReadOnlySpan<byte> updated)
     {
+        original = original.ToArray(); // defensive allocation to ensure the sequence stays the same during replacement
         Main.Data.ReplaceOccurrences(original, updated);
         foreach (var pair in Players.SelectMany(z => z))
             pair.Data.ReplaceOccurrences(original, updated);
diff --git a/NHSE.Core/Structures/Villager/IVillagerOrigin.cs b/NHSE.Core/Structures/Villager/IVillagerOrigin.cs
index cc1a67e..15c182c 100644
--- a/NHSE.Core/Structures/Villager/IVillagerOrigin.cs
+++ b/NHSE.Core/Structures/Villager/IVillagerOrigin.cs
@@ -40,14 +40,14 @@ public static void ChangeOrigins(this IVillagerOrigin visit, IVillagerOrigin hos
     private static void ChangeToHostTown(this IVillagerOrigin visit, IVillagerOrigin host, Span<byte> visitData)
     {
         var hostTown = host.GetTownIdentity();
-        var visitTown = visit.GetTownIdentity();
+        var visitTown = visit.GetTownIdentity().ToArray();
         visitData.ReplaceOccurrences(visitTown, hostTown);
     }
 
     private static void ChangeToHostPlayer(this IVillagerOrigin visit, IVillagerOrigin host, Span<byte> visitData)
     {
         var hostPlayer = host.GetPlayerIdentity();
-        var visitPlayer = visit.GetPlayerIdentity();
+        var visitPlayer = visit.GetPlayerIdentity().ToArray();
         visitData.ReplaceOccurrences(visitPlayer, hostPlayer);
     }
 }
\ No newline at end of file
diff --git a/NHSE.WinForms/Editor.cs b/NHSE.WinForms/Editor.cs
index 54a8574..8734ca4 100644
--- a/NHSE.WinForms/Editor.cs
+++ b/NHSE.WinForms/Editor.cs
@@ -346,14 +346,14 @@ private void SavePlayer(int index)
 
         if (pers.PlayerName != TB_Name.Text)
         {
-            var orig = pers.GetPlayerIdentity();
+            var orig = pers.GetPlayerIdentity().ToArray();
             pers.PlayerName = TB_Name.Text;
             var updated = pers.GetPlayerIdentity();
             SAV.ChangeIdentity(orig, updated);
         }
         if (pers.TownName != TB_TownName.Text)
         {
-            var orig = pers.GetTownIdentity();
+            var orig = pers.GetTownIdentity().ToArray();
             pers.TownName = TB_TownName.Text;
             var updated = pers.GetTownIdentity();
             SAV.ChangeIdentity(orig, updated);