diff --git a/HellionChat/Export/MessageExporter.cs b/HellionChat/Export/MessageExporter.cs
index 3f33006..c6ddb47 100644
--- a/HellionChat/Export/MessageExporter.cs
+++ b/HellionChat/Export/MessageExporter.cs
@@ -92,6 +92,18 @@ internal static class MessageExporter
                 };
             }
 
+            // An export that matched nothing does not replace anything. The
+            // file still has a header and a footer, so moving it would put a
+            // near-empty file where the user's previous export was -- and then
+            // report "no message matched the filter", which reads as "nothing
+            // happened". Dalamud's save dialog has no overwrite confirmation to
+            // fall back on.
+            if (written == 0)
+            {
+                TryDeleteTemp(temp);
+                return 0;
+            }
+
             File.Move(temp, path, overwrite: true);
             return written;
         }
@@ -225,8 +237,13 @@ internal static class MessageExporter
             w.Write($",\"date\":\"{m.Date.ToString("O", CultureInfo.InvariantCulture)}\"");
             w.Write($",\"chat_type\":{(int)m.Code.Type}");
             w.Write($",\"chat_type_name\":\"{chatType}\"");
-            w.Write($",\"source_kind\":{m.Code.Source}");
-            w.Write($",\"target_kind\":{m.Code.Target}");
+            // Cast, not interpolate. These are XivChatRelationKind, and string
+            // interpolation of an enum writes the member name -- so every
+            // message with a recognised relation produced
+            // "source_kind":LocalPlayer, which no parser accepts. This is the
+            // file an access request goes out on.
+            w.Write($",\"source_kind\":{(int)m.Code.Source}");
+            w.Write($",\"target_kind\":{(int)m.Code.Target}");
             w.Write($",\"receiver\":{m.Receiver}");
             w.Write($",\"content_id\":{m.ContentId}");
             w.Write($",\"sender\":{JsonString(SenderText(m))}");
@@ -313,8 +330,17 @@ internal static class MessageExporter
 
     private static string CsvString(string s)
     {
+        // Leading =, +, - and @ make a spreadsheet treat the cell as a formula.
+        // Every value here is text somebody else typed into a chat channel, and
+        // this file exists to be opened in Excel, so a prefixed apostrophe goes
+        // in front. It is the standard defence and it costs one character that
+        // spreadsheets hide.
+        if (s.Length > 0 && s[0] is '=' or '+' or '-' or '@' or '\t' or '\r')
+            s = "'" + s;
+
         if (s.IndexOfAny(['"', ',', '\n', '\r']) < 0)
             return s;
+
         return "\"" + s.Replace("\"", "\"\"") + "\"";
     }
 }
diff --git a/HellionChat/MessageStore.cs b/HellionChat/MessageStore.cs
index 0f390be..b0c6f5a 100644
--- a/HellionChat/MessageStore.cs
+++ b/HellionChat/MessageStore.cs
@@ -493,7 +493,7 @@ internal class MessageStore : IDisposable
         {
             Connection.Execute("DELETE FROM messages;");
             InvalidateFtsIndex();
-            PerformMaintenance();
+            TryPerformMaintenance();
         }
     }
 
@@ -595,7 +595,7 @@ internal class MessageStore : IDisposable
             if (deleted > 0)
             {
                 InvalidateFtsIndex();
-                PerformMaintenance();
+                TryPerformMaintenance();
             }
 
             return deleted;
@@ -628,7 +628,7 @@ internal class MessageStore : IDisposable
             if (deleted > 0)
             {
                 InvalidateFtsIndex();
-                PerformMaintenance();
+                TryPerformMaintenance();
             }
 
             return deleted;
@@ -663,7 +663,7 @@ internal class MessageStore : IDisposable
             if (deleted > 0)
             {
                 InvalidateFtsIndex();
-                PerformMaintenance();
+                TryPerformMaintenance();
             }
 
             return deleted;
@@ -684,6 +684,33 @@ internal class MessageStore : IDisposable
         }
     }
 
+    // Runs maintenance and swallows a failure, for the delete paths only.
+    //
+    // VACUUM needs the database to itself, and a lazily consumed reader on the
+    // primary connection -- which GetMostRecentMessages hands out and the
+    // refilter walks outside the lock -- makes it fail immediately with "cannot
+    // VACUUM - SQL statements in progress". That happens after the DELETE has
+    // committed, so letting it escape means the caller reports "nothing was
+    // removed" about a wipe that emptied the database.
+    //
+    // The rows are gone either way. An uncompacted file is a housekeeping
+    // problem; telling somebody their history is still there when it is not is
+    // a different kind of problem.
+    private void TryPerformMaintenance()
+    {
+        try
+        {
+            PerformMaintenance();
+        }
+        catch (Exception e)
+        {
+            _logger.LogWarning(
+                e,
+                "Maintenance after a delete failed; the rows are gone but the file was not compacted."
+            );
+        }
+    }
+
     private string LogPath => DbPath + "-wal";
 
     internal long DatabaseSize() => !File.Exists(DbPath) ? 0 : new FileInfo(DbPath).Length;
diff --git a/HellionChat/Plugin.cs b/HellionChat/Plugin.cs
index 91c9397..85e9965 100755
--- a/HellionChat/Plugin.cs
+++ b/HellionChat/Plugin.cs
@@ -1064,9 +1064,23 @@ public sealed class Plugin : IAsyncDalamudPlugin
             return false;
 
         // Snapshot the policy so the user can edit settings while the sweep runs.
+        //
+        // Seeded from the spec defaults only when the global limit is not "keep
+        // forever". The slider is labelled "0 = never", and pre-filling 31
+        // channels with 365- and 90-day windows made that label a lie: setting
+        // it to zero still lost free company, linkshell and party history after
+        // ninety days, and the short-circuit in DeleteByRetentionPolicy could
+        // never be reached because the map was never empty.
+        //
+        // Explicit per-channel overrides still apply. Somebody who typed a
+        // number for one channel meant that number.
         var policy = new Dictionary<int, int>();
-        foreach (var (type, days) in Privacy.PrivacyDefaults.DefaultRetentionDays)
-            policy[(int)(ushort)type] = days;
+        if (Config.RetentionDefaultDays > 0)
+        {
+            foreach (var (type, days) in Privacy.PrivacyDefaults.DefaultRetentionDays)
+                policy[(int)(ushort)type] = days;
+        }
+
         // This is the enumerator the wizard's Clear() cuts short. Reading under the
         // same lock the writers take keeps the policy snapshot whole.
         lock (ConfigMapsLock)
@@ -1086,7 +1100,18 @@ public sealed class Plugin : IAsyncDalamudPlugin
             try
             {
                 if (!DbOperations.TryBegin(Util.DbOperation.RetentionSweep))
+                {
+                    // A run the user pressed a button for has to say something.
+                    // The pre-check in StartRetentionSweep only covers a gate
+                    // that was already busy; losing the race here is the same
+                    // outcome and used to be silent.
+                    if (notify)
+                        NotifySweep(
+                            Resources.HellionStrings.Retention_Error,
+                            Dalamud.Interface.ImGuiNotification.NotificationType.Warning
+                        );
                     return;
+                }
 
                 try
                 {
@@ -1142,7 +1167,7 @@ public sealed class Plugin : IAsyncDalamudPlugin
             {
                 Log.Error(e, "Retention sweep failed");
                 if (notify)
-                    Util.WrapperUtil.AddNotification(
+                    NotifySweep(
                         Resources.HellionStrings.Retention_Error,
                         Dalamud.Interface.ImGuiNotification.NotificationType.Error
                     );
@@ -1170,6 +1195,20 @@ public sealed class Plugin : IAsyncDalamudPlugin
         }
     }
 
+    // The sweep is a background thread that can outlive an unload, same as the
+    // settings-tab workers. A notification filed against a plugin that is gone
+    // belongs to nobody.
+    private void NotifySweep(
+        string message,
+        Dalamud.Interface.ImGuiNotification.NotificationType type
+    )
+    {
+        if (_isDisposing)
+            return;
+
+        Util.WrapperUtil.AddNotification(message, type);
+    }
+
     // Read by the settings tab every frame so the manual button can say a run is
     // in progress. The gate itself cannot answer that: it goes busy only once
     // the worker reaches TryBegin, which is after Start returns.
diff --git a/HellionChat/Resources/HellionStrings.Designer.cs b/HellionChat/Resources/HellionStrings.Designer.cs
index 887fb2f..8f70b61 100644
--- a/HellionChat/Resources/HellionStrings.Designer.cs
+++ b/HellionChat/Resources/HellionStrings.Designer.cs
@@ -277,6 +277,8 @@ internal class HellionStrings
     internal static string Settings_Database_Op_Export => Get(nameof(Settings_Database_Op_Export));
     internal static string Settings_Database_Op_Cleanup => Get(nameof(Settings_Database_Op_Cleanup));
     internal static string Settings_Database_Op_Clear => Get(nameof(Settings_Database_Op_Clear));
+    internal static string Settings_Database_Op_Preview => Get(nameof(Settings_Database_Op_Preview));
+    internal static string Settings_Database_Op_Maintenance => Get(nameof(Settings_Database_Op_Maintenance));
 
     // Hellion Chat — Default tab presets (channel-themed)
     internal static string Tabs_Presets_System => Get(nameof(Tabs_Presets_System));
diff --git a/HellionChat/Resources/HellionStrings.ca.resx b/HellionChat/Resources/HellionStrings.ca.resx
index 7354097..52114ac 100644
--- a/HellionChat/Resources/HellionStrings.ca.resx
+++ b/HellionChat/Resources/HellionStrings.ca.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplica</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>vista prèvia</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>manteniment</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.cs.resx b/HellionChat/Resources/HellionStrings.cs.resx
index aaaa3fa..73e8050 100644
--- a/HellionChat/Resources/HellionStrings.cs.resx
+++ b/HellionChat/Resources/HellionStrings.cs.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplikovat</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>náhled</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>údržba</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.da.resx b/HellionChat/Resources/HellionStrings.da.resx
index d13777b..521f41c 100644
--- a/HellionChat/Resources/HellionStrings.da.resx
+++ b/HellionChat/Resources/HellionStrings.da.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplikér</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>forhåndsvisning</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>vedligeholdelse</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.de.resx b/HellionChat/Resources/HellionStrings.de.resx
index e2760fa..b030897 100644
--- a/HellionChat/Resources/HellionStrings.de.resx
+++ b/HellionChat/Resources/HellionStrings.de.resx
@@ -1322,4 +1322,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplizieren</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>Vorschau</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>Wartung</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.el.resx b/HellionChat/Resources/HellionStrings.el.resx
index f35e762..5ac707e 100644
--- a/HellionChat/Resources/HellionStrings.el.resx
+++ b/HellionChat/Resources/HellionStrings.el.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Αντιγραφή</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>προεπισκόπηση</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>συντήρηση</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.es.resx b/HellionChat/Resources/HellionStrings.es.resx
index 105a5c7..46acd7d 100644
--- a/HellionChat/Resources/HellionStrings.es.resx
+++ b/HellionChat/Resources/HellionStrings.es.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplicar</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>vista previa</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>mantenimiento</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.fi.resx b/HellionChat/Resources/HellionStrings.fi.resx
index 0c02e98..d80898d 100644
--- a/HellionChat/Resources/HellionStrings.fi.resx
+++ b/HellionChat/Resources/HellionStrings.fi.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Kahdenna</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>esikatselu</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>ylläpito</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.fr.resx b/HellionChat/Resources/HellionStrings.fr.resx
index 93aeb61..2f17062 100644
--- a/HellionChat/Resources/HellionStrings.fr.resx
+++ b/HellionChat/Resources/HellionStrings.fr.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Dupliquer</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>aperçu</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>maintenance</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.hu.resx b/HellionChat/Resources/HellionStrings.hu.resx
index ed40eb9..43e6153 100644
--- a/HellionChat/Resources/HellionStrings.hu.resx
+++ b/HellionChat/Resources/HellionStrings.hu.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Másolat</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>előnézet</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>karbantartás</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.it.resx b/HellionChat/Resources/HellionStrings.it.resx
index 98a745c..8880a1f 100644
--- a/HellionChat/Resources/HellionStrings.it.resx
+++ b/HellionChat/Resources/HellionStrings.it.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplica</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>anteprima</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>manutenzione</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.ja.resx b/HellionChat/Resources/HellionStrings.ja.resx
index 9b23c70..f1beb26 100644
--- a/HellionChat/Resources/HellionStrings.ja.resx
+++ b/HellionChat/Resources/HellionStrings.ja.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>複製</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>プレビュー</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>メンテナンス</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.ko.resx b/HellionChat/Resources/HellionStrings.ko.resx
index 47cc108..3fb0e96 100644
--- a/HellionChat/Resources/HellionStrings.ko.resx
+++ b/HellionChat/Resources/HellionStrings.ko.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>복제</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>미리보기</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>유지 관리</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.nb.resx b/HellionChat/Resources/HellionStrings.nb.resx
index f3824e9..e1654d5 100644
--- a/HellionChat/Resources/HellionStrings.nb.resx
+++ b/HellionChat/Resources/HellionStrings.nb.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Dupliser</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>forhåndsvisning</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>vedlikehold</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.nl.resx b/HellionChat/Resources/HellionStrings.nl.resx
index 8e5fed6..59bc189 100644
--- a/HellionChat/Resources/HellionStrings.nl.resx
+++ b/HellionChat/Resources/HellionStrings.nl.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Dupliceren</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>voorbeeld</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>onderhoud</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.pl.resx b/HellionChat/Resources/HellionStrings.pl.resx
index 8164f55..7a74f13 100644
--- a/HellionChat/Resources/HellionStrings.pl.resx
+++ b/HellionChat/Resources/HellionStrings.pl.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplikuj</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>podgląd</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>konserwacja</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.pt-BR.resx b/HellionChat/Resources/HellionStrings.pt-BR.resx
index 4c418ea..89fd3dd 100644
--- a/HellionChat/Resources/HellionStrings.pt-BR.resx
+++ b/HellionChat/Resources/HellionStrings.pt-BR.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplicar</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>pré-visualização</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>manutenção</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.pt-PT.resx b/HellionChat/Resources/HellionStrings.pt-PT.resx
index 361a83f..8087376 100644
--- a/HellionChat/Resources/HellionStrings.pt-PT.resx
+++ b/HellionChat/Resources/HellionStrings.pt-PT.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplicar</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>pré-visualização</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>manutenção</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.resx b/HellionChat/Resources/HellionStrings.resx
index 087d394..2f352d2 100644
--- a/HellionChat/Resources/HellionStrings.resx
+++ b/HellionChat/Resources/HellionStrings.resx
@@ -1339,4 +1339,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplicate</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>preview</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>maintenance</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.ro.resx b/HellionChat/Resources/HellionStrings.ro.resx
index cc06371..bc6d3eb 100644
--- a/HellionChat/Resources/HellionStrings.ro.resx
+++ b/HellionChat/Resources/HellionStrings.ro.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplică</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>previzualizare</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>întreținere</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.ru.resx b/HellionChat/Resources/HellionStrings.ru.resx
index de4d70d..891dae5 100644
--- a/HellionChat/Resources/HellionStrings.ru.resx
+++ b/HellionChat/Resources/HellionStrings.ru.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Дублировать</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>предпросмотр</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>обслуживание</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.sv.resx b/HellionChat/Resources/HellionStrings.sv.resx
index c77e20a..2db63e2 100644
--- a/HellionChat/Resources/HellionStrings.sv.resx
+++ b/HellionChat/Resources/HellionStrings.sv.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Duplicera</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>förhandsgranskning</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>underhåll</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.tr.resx b/HellionChat/Resources/HellionStrings.tr.resx
index 7d95d2c..eeeb1c6 100644
--- a/HellionChat/Resources/HellionStrings.tr.resx
+++ b/HellionChat/Resources/HellionStrings.tr.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Çoğalt</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>önizleme</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>bakım</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.uk.resx b/HellionChat/Resources/HellionStrings.uk.resx
index 403ad43..74744c5 100644
--- a/HellionChat/Resources/HellionStrings.uk.resx
+++ b/HellionChat/Resources/HellionStrings.uk.resx
@@ -1327,4 +1327,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>Дублювати</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>попередній перегляд</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>обслуговування</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.zh-Hans.resx b/HellionChat/Resources/HellionStrings.zh-Hans.resx
index a21a232..f5ab8e6 100644
--- a/HellionChat/Resources/HellionStrings.zh-Hans.resx
+++ b/HellionChat/Resources/HellionStrings.zh-Hans.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>复制</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>预览</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>维护</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/Resources/HellionStrings.zh-Hant.resx b/HellionChat/Resources/HellionStrings.zh-Hant.resx
index f4026a6..357b246 100644
--- a/HellionChat/Resources/HellionStrings.zh-Hant.resx
+++ b/HellionChat/Resources/HellionStrings.zh-Hant.resx
@@ -1328,4 +1328,10 @@
   <data name="Settings_Tabs_Duplicate" xml:space="preserve">
     <value>複製</value>
   </data>
+  <data name="Settings_Database_Op_Preview" xml:space="preserve">
+    <value>預覽</value>
+  </data>
+  <data name="Settings_Database_Op_Maintenance" xml:space="preserve">
+    <value>維護</value>
+  </data>
 </root>
\ No newline at end of file
diff --git a/HellionChat/SelfTests/ExportRoundTripStep.cs b/HellionChat/SelfTests/ExportRoundTripStep.cs
index c7e7731..be1ac17 100644
--- a/HellionChat/SelfTests/ExportRoundTripStep.cs
+++ b/HellionChat/SelfTests/ExportRoundTripStep.cs
@@ -125,6 +125,23 @@ internal sealed class ExportRoundTripStep : ISelfTestStep
             failures.Add("export produced no file");
         if (File.Exists(path + ".part"))
             failures.Add("temporary file left behind after a successful export");
+
+        // Parsed, not merely counted. The writer builds JSON by hand, and it
+        // shipped a build where the chat relation kinds were interpolated as
+        // enum names -- "source_kind":LocalPlayer -- which every parser
+        // rejects. A test that only checks the file exists would have passed.
+        try
+        {
+            using var doc = System.Text.Json.JsonDocument.Parse(File.ReadAllText(path));
+            if (!doc.RootElement.TryGetProperty("messages", out var messages))
+                failures.Add("export JSON has no messages array");
+            else if (messages.GetArrayLength() != 1)
+                failures.Add($"export JSON holds {messages.GetArrayLength()} messages, expected 1");
+        }
+        catch (System.Text.Json.JsonException e)
+        {
+            failures.Add($"export JSON does not parse: {e.Message}");
+        }
     }
 
     // Built with empty SeStrings on purpose: the whole point is that the text
diff --git a/HellionChat/Ui/Components/Settings/Tabs/DataPrivacyTab.cs b/HellionChat/Ui/Components/Settings/Tabs/DataPrivacyTab.cs
index e7ea970..8bf389f 100644
--- a/HellionChat/Ui/Components/Settings/Tabs/DataPrivacyTab.cs
+++ b/HellionChat/Ui/Components/Settings/Tabs/DataPrivacyTab.cs
@@ -140,10 +140,11 @@ internal sealed class DataPrivacyTab
                 v => Plugin.Config.RetentionEnabled = v
             );
 
-            // Down to 0, which DeleteByRetentionPolicy reads as "keep forever"
-            // for channels without an override. The slider started at 1, so the
-            // one value that means "never delete anything" was unreachable
-            // through the UI while the label promised it.
+            // Down to 0, which the sweep reads as "keep forever" for every
+            // channel without an explicit override. That only became true in
+            // v1.12.0: the sweep used to seed the spec defaults unconditionally,
+            // so zero still deleted free company and linkshell history after
+            // ninety days while this label said otherwise.
             _w.SliderIntRow(
                 ImGui.GetID("privacy.logging.default"u8),
                 HellionStrings.Retention_Default_Label,
@@ -474,7 +475,7 @@ internal sealed class DataPrivacyTab
                 // MessageCount holds _readLock, and a VACUUM starting under it
                 // is exactly the collision this gate was written for -- being a
                 // read rather than a write does not exempt it.
-                if (!_plugin.DbOperations.TryBegin(DbOperation.Cleanup))
+                if (!_plugin.DbOperations.TryBegin(DbOperation.Preview))
                     return;
 
                 try
@@ -487,7 +488,7 @@ internal sealed class DataPrivacyTab
                 }
                 finally
                 {
-                    _plugin.DbOperations.End(DbOperation.Cleanup);
+                    _plugin.DbOperations.End(DbOperation.Preview);
                 }
             }
             catch (Exception e)
@@ -692,7 +693,7 @@ internal sealed class DataPrivacyTab
         {
             try
             {
-                if (!_plugin.DbOperations.TryBegin(DbOperation.Cleanup))
+                if (!_plugin.DbOperations.TryBegin(DbOperation.Maintenance))
                 {
                     // Said out loud, like every other refusal. A developer tool
                     // that silently does nothing is how you end up debugging the
@@ -707,7 +708,7 @@ internal sealed class DataPrivacyTab
                 }
                 finally
                 {
-                    _plugin.DbOperations.End(DbOperation.Cleanup);
+                    _plugin.DbOperations.End(DbOperation.Maintenance);
                 }
             }
             catch (Exception e)
@@ -880,7 +881,7 @@ internal sealed class DataPrivacyTab
         {
             try
             {
-                if (!_plugin.DbOperations.TryBegin(DbOperation.Cleanup))
+                if (!_plugin.DbOperations.TryBegin(DbOperation.Preview))
                 {
                     NotifyBusy();
                     return;
@@ -892,7 +893,7 @@ internal sealed class DataPrivacyTab
                 }
                 finally
                 {
-                    _plugin.DbOperations.End(DbOperation.Cleanup);
+                    _plugin.DbOperations.End(DbOperation.Preview);
                 }
             }
             catch (Exception e)
@@ -1235,6 +1236,8 @@ internal sealed class DataPrivacyTab
             DbOperation.Export => HellionStrings.Settings_Database_Op_Export,
             DbOperation.Cleanup => HellionStrings.Settings_Database_Op_Cleanup,
             DbOperation.Clear => HellionStrings.Settings_Database_Op_Clear,
+            DbOperation.Preview => HellionStrings.Settings_Database_Op_Preview,
+            DbOperation.Maintenance => HellionStrings.Settings_Database_Op_Maintenance,
             _ => string.Empty,
         };
 
diff --git a/HellionChat/Util/DbOperationGate.cs b/HellionChat/Util/DbOperationGate.cs
index ffa585a..4fc3516 100644
--- a/HellionChat/Util/DbOperationGate.cs
+++ b/HellionChat/Util/DbOperationGate.cs
@@ -8,6 +8,12 @@ internal enum DbOperation
     Export,
     Cleanup,
     Clear,
+
+    // Read-only, but they hold the store long enough to matter: the preview
+    // scans every row, the metadata read takes the read lock, and maintenance
+    // rewrites the file without touching a single row.
+    Preview,
+    Maintenance,
 }
 
 // One gate for every operation that holds the message store for longer than a
@@ -47,6 +53,16 @@ internal sealed class DbOperationGate
 
     internal long Revision => Interlocked.Read(ref _revision);
 
+    // Which operations can change what a preview counted. Getting this wrong in
+    // the permissive direction only costs a needless recount; getting it wrong
+    // the other way lets somebody confirm a number that is no longer true.
+    //
+    // The preview itself must not be in here, and that is not a detail: it takes
+    // the gate, so counting its own release would mark every preview stale the
+    // instant it finished and the apply button would never appear.
+    private static bool Mutates(DbOperation operation) =>
+        operation is DbOperation.RetentionSweep or DbOperation.Cleanup or DbOperation.Clear;
+
     internal bool IsBusy => _current != DbOperation.None;
 
     // False when another operation already owns the store. Callers must not
@@ -84,7 +100,7 @@ internal sealed class DbOperationGate
                 return;
 
             _current = DbOperation.None;
-            if (operation != DbOperation.Export)
+            if (Mutates(operation))
                 Interlocked.Increment(ref _revision);
         }
     }