(bugfix): keep unread and flags stable across cancel and sync races

CHANGELOG.md

@@ -6,6 +6,19 @@ The format follows [Keep a Changelog](https://keepachangelog.com/) and [Semantic
 
 ## [Unreleased]
 
+## [0.4.5] - 2026-10-31
+
+Unread and flag updates stay local when the server store is cancelled or races with sync. Pending Seen/Flagged wait for STORE ack before background sync can overwrite them.
+
+### Fixed
+
+- Opening an unread message no longer brings the unread dot back when you select another row: mark-as-read is not cancelled with the reading pane, and IMAP cancel is not treated as a store failure.
+- Manual Mark Read/Unread/Flag and folder mark-all-read keep optimistic state off the busy `_work` token; IMAP flag stores use a non-folder CTS and pending archive flags until STORE succeeds (or soft “not connected”, which stays pending and flushes on reconnect).
+- Background sync and header upserts no longer clobber newer local Seen/Flagged; `UpsertHeaders` skips flag overwrite by default and `UpdateFlags` respects pending UIDs.
+- IMAP MOVE no longer falls back to copy-then-delete on cancel; remaining UIDs are checked before copy/expunge. Cross-mailbox moves delete each source UID after a successful copy.
+- Rules and headless sync write archive flags only after a successful STORE. SyncFolder no longer advances past a folder on list failure.
+- POP3 Mark Read works locally; spam junk/inbox destinations resolve per message mailbox; Priority is restored on failed flag updates.
+
 ## [0.4.4] - 2026-10-29
 
 HTML mail blocks remote images by default. Windows setup upgrades keep Identity Hub sibling DLLs. Store MSIX is built with each release.

src/Directory.Build.props

@@ -3,7 +3,7 @@
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
     <ImplicitUsings>enable</ImplicitUsings>
-    <Version>0.4.4</Version>
+    <Version>0.4.5</Version>
     <Product>Postclient</Product>
     <AssemblyTitle>Postclient</AssemblyTitle>
     <Authors>Maksym Sadovnychyy</Authors>

src/MaksIT.PostClient.Client/Mail/ImapMailSession.cs

@@ -69,6 +69,10 @@ public sealed class ImapMailSession : IMailSession {
           cancellationToken).ConfigureAwait(false);
         await MailKitAuth.AuthenticateAsync(client, account, resolved.Value, cancellationToken).ConfigureAwait(false);
       }
+      catch (OperationCanceledException) {
+        client.Dispose();
+        throw;
+      }
       catch (Exception ex) {
         client.Dispose();
         return Result.UnprocessableEntity(MailAuthHint.Incoming(account, ex.Message));
@@ -117,6 +121,9 @@ public sealed class ImapMailSession : IMailSession {
 
       return Result<IReadOnlyList<MailFolderInfo>>.Ok(MailFolderCatalog.Normalize(folders, layout));
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result<IReadOnlyList<MailFolderInfo>>.UnprocessableEntity(null, ex.Message);
     }
@@ -240,7 +247,12 @@ public sealed class ImapMailSession : IMailSession {
         Incomplete = range.Incomplete
       });
     }
+    catch (OperationCanceledException) {
+      ClearListCursor(folder);
+      throw;
+    }
     catch (Exception ex) {
+      ClearListCursor(folder);
       return Result<MailFolderSync>.UnprocessableEntity(null, ex.Message);
     }
   }
@@ -358,6 +370,9 @@ public sealed class ImapMailSession : IMailSession {
       var uid = await imapFolder.AppendAsync(new AppendRequest(mime), cancellationToken).ConfigureAwait(false);
       return Result<uint?>.Ok(uid?.Id);
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result<uint?>.UnprocessableEntity(null, ex.Message);
     }
@@ -414,17 +429,42 @@ public sealed class ImapMailSession : IMailSession {
         else
           await CopyThenDeleteAsync(source, dest, uids, cancellationToken).ConfigureAwait(false);
       }
+      catch (OperationCanceledException) {
+        throw;
+      }
       catch (Exception) when (client.Capabilities.HasFlag(ImapCapabilities.Move)) {
-        await CopyThenDeleteAsync(source, dest, uids, cancellationToken).ConfigureAwait(false);
+        var remaining = await RemainingUidsAsync(source, uids, cancellationToken).ConfigureAwait(false);
+        if (remaining.Count > 0)
+          await CopyThenDeleteAsync(source, dest, remaining, cancellationToken).ConfigureAwait(false);
       }
 
       return Result.Ok();
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result.UnprocessableEntity(ex.Message);
     }
   }
 
+  private static async Task<IList<UniqueId>> RemainingUidsAsync(
+    IMailFolder source,
+    IList<UniqueId> uids,
+    CancellationToken cancellationToken) {
+    if (uids.Count == 0)
+      return uids;
+    var set = new UniqueIdSet();
+    foreach (var uid in uids)
+      set.Add(uid);
+    var found = await source.SearchAsync(SearchQuery.Uids(set), cancellationToken).ConfigureAwait(false);
+    if (found.Count == 0)
+      return Array.Empty<UniqueId>();
+    if (found.Count == uids.Count)
+      return uids;
+    return found.ToList();
+  }
+
   private static async Task CopyThenDeleteAsync(
     IMailFolder source,
     IMailFolder dest,
@@ -481,6 +521,9 @@ public sealed class ImapMailSession : IMailSession {
       catch (Exception ex) when (attempt == 0 && IsBrokenConnection(ex)) {
         DropSocket();
       }
+      catch (OperationCanceledException) {
+        throw;
+      }
       catch (Exception ex) {
         return Result.UnprocessableEntity(ex.Message);
       }
@@ -518,6 +561,9 @@ public sealed class ImapMailSession : IMailSession {
       await parent.CreateAsync(leaf, true, cancellationToken).ConfigureAwait(false);
       return Result.Ok();
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result.UnprocessableEntity(ex.Message);
     }
@@ -561,6 +607,9 @@ public sealed class ImapMailSession : IMailSession {
       await imapFolder.RenameAsync(parent, leaf, cancellationToken).ConfigureAwait(false);
       return Result.Ok();
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result.UnprocessableEntity(ex.Message);
     }
@@ -614,6 +663,9 @@ public sealed class ImapMailSession : IMailSession {
 
       return Result.Ok();
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result.UnprocessableEntity(ex.Message);
     }
@@ -672,6 +724,9 @@ public sealed class ImapMailSession : IMailSession {
 
       return Result.Ok();
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result.UnprocessableEntity(ex.Message);
     }
@@ -707,6 +762,9 @@ public sealed class ImapMailSession : IMailSession {
         cancellationToken).ConfigureAwait(false);
       return Result.Ok();
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result.UnprocessableEntity(ex.Message);
     }
@@ -1020,6 +1078,9 @@ public sealed class ImapMailSession : IMailSession {
       if (rows.Count > 0 || folder.Count == 0)
         return rows;
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch {
     }
 

src/MaksIT.PostClient.Client/Mail/MailSyncEngine.cs

@@ -200,12 +200,12 @@ public sealed class MailSyncEngine {
     var page = await session.ListMessagesAsync(folder, known, cancellationToken, MailPipeline.HeaderPage)
       .ConfigureAwait(false);
     if (!page.IsSuccess)
-      return true;
+      return false;
     var sync = page.Value ?? new MailFolderSync();
     _archive.SetKeywordIndexEnabled(box.Id, box.InitialSyncCompleted);
     if (sync.Flags.Count > 0)
       _archive.UpdateFlags(box.Id, folder, sync.Flags.Select(f => (f.Id, f.IsSeen, f.IsFlagged)));
-    _archive.UpsertHeaders(box.Id, sync.Headers.Select(MailArchiveMap.FromHeader));
+    _archive.UpsertHeaders(box.Id, sync.Headers.Select(MailArchiveMap.FromHeader), updateFlags: false);
     if (sync.Present is not null) {
       var keep = sync.Present.ToHashSet();
       var gone = _archive.Uids(box.Id, folder).Where(uid => !keep.Contains(uid)).ToList();
@@ -343,18 +343,30 @@ public sealed class MailSyncEngine {
     }
 
     if (read.Count > 0) {
-      await session.SetMessageFlagsAsync(folder, read, new MailFlagUpdate { Seen = true }, cancellationToken)
+      var stored = await session
+        .SetMessageFlagsAsync(folder, read, new MailFlagUpdate { Seen = true }, cancellationToken)
         .ConfigureAwait(false);
+      if (stored.IsSuccess)
         _archive.UpdateFlags(
           box.Id,
           folder,
           headers.Where(header => read.Contains(header.Id))
-          .Select(header => (header.Id, true, header.IsFlagged || flagged.Contains(header.Id))));
+            .Select(header => (header.Id, true, header.IsFlagged || flagged.Contains(header.Id))),
+          respectPending: true);
     }
 
-    if (flagged.Count > 0)
+    if (flagged.Count > 0) {
-      await session.SetMessageFlagsAsync(folder, flagged, new MailFlagUpdate { Flagged = true }, cancellationToken)
+      var stored = await session
+        .SetMessageFlagsAsync(folder, flagged, new MailFlagUpdate { Flagged = true }, cancellationToken)
         .ConfigureAwait(false);
+      if (stored.IsSuccess)
+        _archive.UpdateFlags(
+          box.Id,
+          folder,
+          headers.Where(header => flagged.Contains(header.Id))
+            .Select(header => (header.Id, header.IsSeen || read.Contains(header.Id), true)),
+          respectPending: true);
+    }
   }
 
   private async Task RetentionAsync(

src/MaksIT.PostClient.Client/Mail/Pop3MailSession.cs

@@ -55,6 +55,10 @@ public sealed class Pop3MailSession : IMailSession {
           cancellationToken).ConfigureAwait(false);
         await MailKitAuth.AuthenticateAsync(client, account, resolved.Value, cancellationToken).ConfigureAwait(false);
       }
+      catch (OperationCanceledException) {
+        client.Dispose();
+        throw;
+      }
       catch (Exception ex) {
         client.Dispose();
         return Result.UnprocessableEntity(MailAuthHint.Incoming(account, ex.Message));
@@ -159,6 +163,9 @@ public sealed class Pop3MailSession : IMailSession {
         Incomplete = true
       });
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result<MailFolderSync>.UnprocessableEntity(null, ex.Message);
     }
@@ -180,10 +187,11 @@ public sealed class Pop3MailSession : IMailSession {
     if (client is null)
       return Result<MailMessageBody>.UnprocessableEntity(null, "Not connected.");
 
-    using var linked = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+    using var timeout = interactive ? null : new CancellationTokenSource(MailFetch.BackfillTimeout);
-    using var abort = linked.Token.Register(DropSocket);
+    using var linked = timeout is null
-    if (!interactive)
+      ? CancellationTokenSource.CreateLinkedTokenSource(cancellationToken)
-      linked.CancelAfter(MailFetch.BackfillTimeout);
+      : CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeout.Token);
+    using var abort = timeout is null ? default : timeout.Token.Register(DropSocket);
     MimeMessage mime;
     try {
       var index = (int)id;

src/MaksIT.PostClient.Client/Mail/PstMailSession.cs

@@ -73,6 +73,9 @@ public sealed class PstMailSession : IMailSession {
         OpenStore(path);
         return Task.FromResult(Result.Ok());
       }
+      catch (OperationCanceledException) {
+        throw;
+      }
       catch (Exception ex) {
         return Task.FromResult(Result.UnprocessableEntity(WriteError(ex)));
       }
@@ -104,6 +107,9 @@ public sealed class PstMailSession : IMailSession {
         return Task.FromResult(Result<IReadOnlyList<MailFolderInfo>>.Ok(
           MailFolderCatalog.Normalize(folders, MailFolderLayout.Store)));
       }
+      catch (OperationCanceledException) {
+        throw;
+      }
       catch (Exception ex) {
         return Task.FromResult(Result<IReadOnlyList<MailFolderInfo>>.UnprocessableEntity(null, ex.Message));
       }
@@ -279,6 +285,9 @@ public sealed class PstMailSession : IMailSession {
         Incomplete = incomplete
       });
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result<MailFolderSync>.UnprocessableEntity(null, ex.Message);
     }
@@ -329,6 +338,9 @@ public sealed class PstMailSession : IMailSession {
       using var stream = new MemoryStream(eml, writable: false);
       mime = await MimeMessage.LoadAsync(stream, cancellationToken).ConfigureAwait(false);
     }
+    catch (OperationCanceledException) {
+      throw;
+    }
     catch (Exception ex) {
       return Result<uint?>.UnprocessableEntity(null, ex.Message);
     }
@@ -603,6 +615,15 @@ public sealed class PstMailSession : IMailSession {
         if (!copy.IsSuccess)
           return copy;
       }
+      catch (OperationCanceledException) {
+        try {
+          OpenStore(path);
+        }
+        catch {
+        }
+
+        throw;
+      }
       catch (Exception ex) {
         try {
           OpenStore(path);

src/MaksIT.PostClient.Shared/Archive/MailArchiveCatalog.cs

@@ -118,8 +118,11 @@ public sealed class MailArchiveCatalog : IDisposable {
     return store;
   }
 
-  public void UpsertHeaders(string mailboxId, IEnumerable<MailArchiveHeader> headers) =>
+  public void UpsertHeaders(
-    OffUi(() => Use(mailboxId, store => store.UpsertHeaders(mailboxId, headers)));
+    string mailboxId,
+    IEnumerable<MailArchiveHeader> headers,
+    bool updateFlags = false) =>
+    OffUi(() => Use(mailboxId, store => store.UpsertHeaders(mailboxId, headers, updateFlags)));
 
   public void SetKeywordIndexEnabled(string mailboxId, bool enabled) =>
     OffUi(() => {
@@ -146,8 +149,27 @@ public sealed class MailArchiveCatalog : IDisposable {
   public void UpdateFlags(
     string mailboxId,
     string folder,
-    IEnumerable<(uint Uid, bool IsSeen, bool IsFlagged)> flags) =>
+    IEnumerable<(uint Uid, bool IsSeen, bool IsFlagged)> flags,
-    OffUi(() => Use(mailboxId, store => store.UpdateFlags(mailboxId, folder, flags)));
+    bool respectPending = true) =>
+    OffUi(() => Use(mailboxId, store => store.UpdateFlags(mailboxId, folder, flags, respectPending)));
+
+  public void SetLocalFlags(
+    string mailboxId,
+    string folder,
+    IEnumerable<(uint Uid, bool IsSeen, bool IsFlagged)> flags,
+    bool pending = true) =>
+    OffUi(() => Use(mailboxId, store => store.SetLocalFlags(mailboxId, folder, flags, pending)));
+
+  public void ClearPendingFlags(
+    string mailboxId,
+    string folder,
+    IEnumerable<uint> uids) =>
+    OffUi(() => Use(mailboxId, store => store.ClearPendingFlags(mailboxId, folder, uids)));
+
+  public IReadOnlyList<(string Folder, uint Uid, bool IsSeen, bool IsFlagged)> ListAllPendingFlags(
+    string mailboxId) =>
+    OffUi(() => TryGet(mailboxId)?.ListAllPendingFlags(mailboxId)
+      ?? (IReadOnlyList<(string Folder, uint Uid, bool IsSeen, bool IsFlagged)>)[]);
 
   public void UpsertBody(
     string mailboxId,

src/MaksIT.PostClient.Shared/Archive/MailArchiveStore.cs

@@ -23,12 +23,25 @@ public sealed partial class MailArchiveStore : IDisposable {
     EnsureSchema();
   }
 
-  public void UpsertHeaders(string mailboxId, IEnumerable<MailArchiveHeader> headers) {
+  public void UpsertHeaders(
+    string mailboxId,
+    IEnumerable<MailArchiveHeader> headers,
+    bool updateFlags = false) {
     ArgumentNullException.ThrowIfNull(headers);
     lock (_gate) {
       using var tx = _db.BeginTransaction();
-      foreach (var header in headers)
+      foreach (var header in headers) {
-        UpsertHeader(tx, mailboxId, header, updateFlags: true);
+        var applyFlags = updateFlags;
+        if (applyFlags && TryReadPending(tx, mailboxId, header.Folder, header.Uid, out var pending)) {
+          if (pending.IsSeen == header.IsSeen && pending.IsFlagged == header.IsFlagged)
+            ClearPending(tx, mailboxId, header.Folder, header.Uid);
+          else
+            applyFlags = false;
+        }
+
+        UpsertHeader(tx, mailboxId, header, updateFlags: applyFlags);
+      }
+
       tx.Commit();
     }
   }
@@ -36,11 +49,19 @@ public sealed partial class MailArchiveStore : IDisposable {
   public void UpdateFlags(
     string mailboxId,
     string folder,
-    IEnumerable<(uint Uid, bool IsSeen, bool IsFlagged)> flags) {
+    IEnumerable<(uint Uid, bool IsSeen, bool IsFlagged)> flags,
+    bool respectPending = true) {
     ArgumentNullException.ThrowIfNull(flags);
     lock (_gate) {
       using var tx = _db.BeginTransaction();
       foreach (var row in flags) {
+        if (respectPending && TryReadPending(tx, mailboxId, folder, row.Uid, out var pending)) {
+          if (pending.IsSeen == row.IsSeen && pending.IsFlagged == row.IsFlagged)
+            ClearPending(tx, mailboxId, folder, row.Uid);
+          else
+            continue;
+        }
+
         using var cmd = _db.CreateCommand();
         cmd.Transaction = tx;
         cmd.CommandText = """
@@ -54,12 +75,83 @@ public sealed partial class MailArchiveStore : IDisposable {
         cmd.Parameters.AddWithValue("$f", folder);
         cmd.Parameters.AddWithValue("$u", row.Uid);
         cmd.ExecuteNonQuery();
+        if (!respectPending)
+          ClearPending(tx, mailboxId, folder, row.Uid);
+      }
+
+      tx.Commit();
+    }
+  }
+
+  public void SetLocalFlags(
+    string mailboxId,
+    string folder,
+    IEnumerable<(uint Uid, bool IsSeen, bool IsFlagged)> flags,
+    bool pending = true) {
+    ArgumentNullException.ThrowIfNull(flags);
+    lock (_gate) {
+      using var tx = _db.BeginTransaction();
+      foreach (var row in flags) {
+        using (var cmd = _db.CreateCommand()) {
+          cmd.Transaction = tx;
+          cmd.CommandText = """
+            UPDATE messages
+            SET is_seen = $seen, is_flagged = $flag
+            WHERE mailbox_id = $m AND folder = $f AND uid = $u;
+            """;
+          cmd.Parameters.AddWithValue("$seen", row.IsSeen ? 1 : 0);
+          cmd.Parameters.AddWithValue("$flag", row.IsFlagged ? 1 : 0);
+          cmd.Parameters.AddWithValue("$m", mailboxId);
+          cmd.Parameters.AddWithValue("$f", folder);
+          cmd.Parameters.AddWithValue("$u", row.Uid);
+          cmd.ExecuteNonQuery();
+        }
+
+        if (pending)
+          UpsertPending(tx, mailboxId, folder, row.Uid, row.IsSeen, row.IsFlagged);
+        else
+          ClearPending(tx, mailboxId, folder, row.Uid);
       }
 
       tx.Commit();
     }
   }
 
+  public void ClearPendingFlags(
+    string mailboxId,
+    string folder,
+    IEnumerable<uint> uids) {
+    ArgumentNullException.ThrowIfNull(uids);
+    lock (_gate) {
+      using var tx = _db.BeginTransaction();
+      foreach (var uid in uids)
+        ClearPending(tx, mailboxId, folder, uid);
+      tx.Commit();
+    }
+  }
+
+  public IReadOnlyList<(string Folder, uint Uid, bool IsSeen, bool IsFlagged)> ListAllPendingFlags(
+    string mailboxId) {
+    lock (_gate) {
+      using var cmd = _db.CreateCommand();
+      cmd.CommandText = """
+        SELECT folder, uid, is_seen, is_flagged
+        FROM pending_flags
+        WHERE mailbox_id = $m;
+        """;
+      cmd.Parameters.AddWithValue("$m", mailboxId);
+      var rows = new List<(string Folder, uint Uid, bool IsSeen, bool IsFlagged)>();
+      using var reader = cmd.ExecuteReader();
+      while (reader.Read())
+        rows.Add((
+          reader.GetString(0),
+          (uint)reader.GetInt64(1),
+          reader.GetInt64(2) != 0,
+          reader.GetInt64(3) != 0));
+      return rows;
+    }
+  }
+
   public void UpsertBody(
     string mailboxId,
     MailArchiveHeader header,
@@ -1297,6 +1389,14 @@ public sealed partial class MailArchiveStore : IDisposable {
         fingerprint TEXT PRIMARY KEY,
         dismissed_utc TEXT NOT NULL DEFAULT ''
       );
+      CREATE TABLE IF NOT EXISTS pending_flags (
+        mailbox_id TEXT NOT NULL,
+        folder TEXT NOT NULL,
+        uid INTEGER NOT NULL,
+        is_seen INTEGER NOT NULL,
+        is_flagged INTEGER NOT NULL,
+        PRIMARY KEY (mailbox_id, folder, uid)
+      );
       """;
     cmd.ExecuteNonQuery();
     EnsureColumn("messages", "trashed_utc", "TEXT NOT NULL DEFAULT ''");
@@ -1304,6 +1404,73 @@ public sealed partial class MailArchiveStore : IDisposable {
     EnsureColumn("messages", "spam_score", "REAL");
   }
 
+  private static bool TryReadPending(
+    SqliteTransaction tx,
+    string mailboxId,
+    string folder,
+    uint uid,
+    out (bool IsSeen, bool IsFlagged) pending) {
+    using var cmd = tx.Connection!.CreateCommand();
+    cmd.Transaction = tx;
+    cmd.CommandText = """
+      SELECT is_seen, is_flagged
+      FROM pending_flags
+      WHERE mailbox_id = $m AND folder = $f AND uid = $u;
+      """;
+    cmd.Parameters.AddWithValue("$m", mailboxId);
+    cmd.Parameters.AddWithValue("$f", folder);
+    cmd.Parameters.AddWithValue("$u", uid);
+    using var reader = cmd.ExecuteReader();
+    if (!reader.Read()) {
+      pending = default;
+      return false;
+    }
+
+    pending = (reader.GetInt64(0) != 0, reader.GetInt64(1) != 0);
+    return true;
+  }
+
+  private static void UpsertPending(
+    SqliteTransaction tx,
+    string mailboxId,
+    string folder,
+    uint uid,
+    bool isSeen,
+    bool isFlagged) {
+    using var cmd = tx.Connection!.CreateCommand();
+    cmd.Transaction = tx;
+    cmd.CommandText = """
+      INSERT INTO pending_flags (mailbox_id, folder, uid, is_seen, is_flagged)
+      VALUES ($m, $f, $u, $seen, $flag)
+      ON CONFLICT(mailbox_id, folder, uid) DO UPDATE SET
+        is_seen = excluded.is_seen,
+        is_flagged = excluded.is_flagged;
+      """;
+    cmd.Parameters.AddWithValue("$m", mailboxId);
+    cmd.Parameters.AddWithValue("$f", folder);
+    cmd.Parameters.AddWithValue("$u", uid);
+    cmd.Parameters.AddWithValue("$seen", isSeen ? 1 : 0);
+    cmd.Parameters.AddWithValue("$flag", isFlagged ? 1 : 0);
+    cmd.ExecuteNonQuery();
+  }
+
+  private static void ClearPending(
+    SqliteTransaction tx,
+    string mailboxId,
+    string folder,
+    uint uid) {
+    using var cmd = tx.Connection!.CreateCommand();
+    cmd.Transaction = tx;
+    cmd.CommandText = """
+      DELETE FROM pending_flags
+      WHERE mailbox_id = $m AND folder = $f AND uid = $u;
+      """;
+    cmd.Parameters.AddWithValue("$m", mailboxId);
+    cmd.Parameters.AddWithValue("$f", folder);
+    cmd.Parameters.AddWithValue("$u", uid);
+    cmd.ExecuteNonQuery();
+  }
+
   private void EnsureColumn(string table, string column, string definition) {
     using var info = _db.CreateCommand();
     info.CommandText = "PRAGMA table_info(" + table + ");";

src/MaksIT.PostClient.Tests/Archive/ArchiveTests.cs

@@ -191,6 +191,96 @@ public class MailArchiveStoreTests {
     }
   }
 
+  [Fact]
+  public void PendingFlags_BlockStaleServerSeenUntilAck() {
+    var path = Path.Combine(Path.GetTempPath(), "postclient-archive-" + Guid.NewGuid().ToString("N") + ".db");
+    try {
+      using var store = new MailArchiveStore(path);
+      store.UpsertHeaders("box", [
+        new MailArchiveHeader {
+          Uid = 9,
+          Folder = "INBOX",
+          Subject = "Unread",
+          From = "a@b.c",
+          Date = DateTimeOffset.Parse("2026-01-01T10:00:00Z"),
+          IsSeen = false
+        }
+      ]);
+      store.SetLocalFlags("box", "INBOX", [(9u, true, false)], pending: true);
+      Assert.True(Assert.Single(store.ListFolder("box", "INBOX")).IsSeen);
+      store.UpdateFlags("box", "INBOX", [(9u, false, false)]);
+      Assert.True(Assert.Single(store.ListFolder("box", "INBOX")).IsSeen);
+      store.UpdateFlags("box", "INBOX", [(9u, true, false)]);
+      Assert.True(Assert.Single(store.ListFolder("box", "INBOX")).IsSeen);
+      Assert.Empty(store.ListAllPendingFlags("box"));
+    }
+    finally {
+      DeleteArchive(path);
+    }
+  }
+
+  [Fact]
+  public void UpsertHeaders_DoesNotClobberPendingSeen() {
+    var path = Path.Combine(Path.GetTempPath(), "postclient-archive-" + Guid.NewGuid().ToString("N") + ".db");
+    try {
+      using var store = new MailArchiveStore(path);
+      store.UpsertHeaders("box", [
+        new MailArchiveHeader {
+          Uid = 11,
+          Folder = "INBOX",
+          Subject = "A",
+          From = "a@b.c",
+          Date = DateTimeOffset.Parse("2026-01-01T10:00:00Z"),
+          IsSeen = false
+        }
+      ]);
+      store.SetLocalFlags("box", "INBOX", [(11u, true, false)], pending: true);
+      store.UpsertHeaders(
+        "box",
+        [
+          new MailArchiveHeader {
+            Uid = 11,
+            Folder = "INBOX",
+            Subject = "A renamed",
+            From = "a@b.c",
+            Date = DateTimeOffset.Parse("2026-01-01T10:00:00Z"),
+            IsSeen = false
+          }
+        ],
+        updateFlags: true);
+      var row = Assert.Single(store.ListFolder("box", "INBOX"));
+      Assert.Equal("A renamed", row.Subject);
+      Assert.True(row.IsSeen);
+    }
+    finally {
+      DeleteArchive(path);
+    }
+  }
+
+  [Fact]
+  public void SetLocalFlags_WithoutPending_AllowsServerOverwrite() {
+    var path = Path.Combine(Path.GetTempPath(), "postclient-archive-" + Guid.NewGuid().ToString("N") + ".db");
+    try {
+      using var store = new MailArchiveStore(path);
+      store.UpsertHeaders("box", [
+        new MailArchiveHeader {
+          Uid = 12,
+          Folder = "INBOX",
+          Subject = "Local",
+          From = "a@b.c",
+          Date = DateTimeOffset.Parse("2026-01-01T10:00:00Z"),
+          IsSeen = false
+        }
+      ]);
+      store.SetLocalFlags("box", "INBOX", [(12u, true, false)], pending: false);
+      store.UpdateFlags("box", "INBOX", [(12u, false, false)]);
+      Assert.False(Assert.Single(store.ListFolder("box", "INBOX")).IsSeen);
+    }
+    finally {
+      DeleteArchive(path);
+    }
+  }
+
   [Fact]
   public void UpsertHeaders_KeepsPreviousSizeWhenIncomingIsZero() {
     var path = Path.Combine(Path.GetTempPath(), "postclient-archive-" + Guid.NewGuid().ToString("N") + ".db");

src/MaksIT.PostClient.UI/ViewModels/MainViewModel.Pipeline.cs

@@ -100,22 +100,25 @@ public partial class MainViewModel {
       return true;
     }
 
-    if (token.IsCancellationRequested || Volatile.Read(ref _mailEpoch) != epoch)
+    if (token.IsCancellationRequested)
       return true;
+    var applyFlags = Volatile.Read(ref _mailEpoch) == epoch;
     _folderFailUtc.Remove(key);
 
     var sync = listed.Value ?? new MailFolderSync();
-    ApplyFolderSync(slot.MailboxId, slot.Folder, sync);
+    ApplyFolderSync(slot.MailboxId, slot.Folder, sync, applyFlags);
     var fresh = sync.Headers.Where(header => !known.Contains(header.Id)).ToList();
-    if (fresh.Count > 0) {
+    var openFolder = false;
-      EnqueueFreshRules(slot.MailboxId, slot.Folder, fresh);
     await UiAsync(() => {
-        if (SelectedMailbox?.Id.Equals(slot.MailboxId, StringComparison.OrdinalIgnoreCase) == true
+      openFolder = SelectedMailbox?.Id.Equals(slot.MailboxId, StringComparison.OrdinalIgnoreCase) == true
-            && SelectedFolder?.FullName.Equals(slot.Folder, StringComparison.OrdinalIgnoreCase) == true)
+        && SelectedFolder?.FullName.Equals(slot.Folder, StringComparison.OrdinalIgnoreCase) == true;
+      if (fresh.Count > 0 && openFolder)
         NoticeNewMail(fresh);
     }).ConfigureAwait(false);
+    if (fresh.Count > 0)
+      EnqueueFreshRules(slot.MailboxId, slot.Folder, fresh);
+    if (openFolder && (fresh.Count > 0 || (applyFlags && sync.Flags.Count > 0)))
       await ShowArchiveAsync(slot.MailboxId, slot.Folder, token).ConfigureAwait(false);
-    }
 
     await SetIndexLineAsync(GlobalIndexLine(), token).ConfigureAwait(false);
     var counts = _archive.FolderCounts(slot.MailboxId, slot.Folder);

src/MaksIT.PostClient.UI/ViewModels/MainViewModel.cs

@@ -1829,7 +1829,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       return;
     if (IsLoadedBody(row.Header) && _reading is not null) {
       if (!row.Header.IsSeen)
-        _ = MarkOpenedReadAsync(row.Header, CancellationToken.None);
+        _ = MarkOpenedReadAsync(row.Header);
       ShowMessageWindow(_reading);
       return;
     }
@@ -1932,34 +1932,47 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
   [RelayCommand(CanExecute = nameof(CanOrganize))]
   private async Task MarkSpamAsync() {
     var rows = TargetRows();
-    if (rows.Count == 0 || SelectedMailbox is null)
+    if (rows.Count == 0)
       return;
     foreach (var row in rows)
       _archive.MarkSpam(row.MailboxId, row.Header.Folder, row.Header.Id, EmbeddingModelSpec.Id);
-    var junk = JunkFolder(SelectedMailbox);
+    var moved = false;
-    if (string.IsNullOrWhiteSpace(junk)) {
+    foreach (var group in rows.GroupBy(row => row.MailboxId, StringComparer.OrdinalIgnoreCase)) {
-      Status = Copy.SpamNoJunk;
+      var box = MailboxById(group.Key) ?? SelectedMailbox;
-      PaintSpam(rows);
+      if (box is null)
-      return;
+        continue;
+      var junk = JunkFolder(box);
+      if (string.IsNullOrWhiteSpace(junk))
+        continue;
+      moved = true;
+      await MoveRowsAsync(group.ToList(), junk);
     }
 
-    await MoveRowsAsync(rows, junk);
+    if (!moved) {
+      Status = Copy.SpamNoJunk;
+      PaintSpam(rows);
+    }
   }
 
   [RelayCommand(CanExecute = nameof(CanOrganize))]
   private async Task MarkNotSpamAsync() {
     var rows = TargetRows();
-    if (rows.Count == 0 || SelectedMailbox is null)
+    if (rows.Count == 0)
       return;
     foreach (var row in rows)
       _archive.DismissMessage(row.MailboxId, row.Header.Folder, row.Header.Id);
-    var inbox = InboxOf(SelectedMailbox)?.FullName ?? "";
+    foreach (var group in rows.GroupBy(row => row.MailboxId, StringComparer.OrdinalIgnoreCase)) {
+      var box = MailboxById(group.Key) ?? SelectedMailbox;
+      if (box is null)
+        continue;
+      var inbox = InboxOf(box)?.FullName ?? "";
       if (string.IsNullOrWhiteSpace(inbox)) {
-      PaintSpam(rows);
+        PaintSpam(group);
-      return;
+        continue;
       }
 
-    await MoveRowsAsync(rows, inbox);
+      await MoveRowsAsync(group.ToList(), inbox);
+    }
   }
 
   public IReadOnlyList<SpamListItem> SpamExamples() =>
@@ -2197,7 +2210,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       row => row.Header.Priority = priority);
   }
 
-  [RelayCommand(CanExecute = nameof(CanOrganize), AllowConcurrentExecutions = true)]
+  [RelayCommand(CanExecute = nameof(CanOrganize))]
   private async Task DeleteMessagesAsync() {
     var rows = TargetRows();
     if (rows.Count == 0)
@@ -2375,27 +2388,59 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     var session = ActiveSession;
     var box = SelectedMailbox;
     var folder = SelectedFolder;
-    if (session is not { IsConnected: true, SupportsFolders: true } || box is null || folder is null)
+    if (box is null || folder is null)
       return;
-    await RunAsync(Copy.UpdatingFlags, async token => {
     NoteUiMailChange();
-      var result = await session.SetFolderSeenAsync(folder.FullName, seen, token);
+    var previous = Messages.Select(row => (row, row.Header.IsSeen, row.Header.IsFlagged)).ToList();
-      if (!result.IsSuccess) {
-        Status = string.Join(" ", result.Messages);
-        return;
-      }
-
-      _archive.SetSeen(box.Id, folder.FullName, seen);
     foreach (var row in Messages) {
       row.Header.IsSeen = seen;
       row.RefreshMarks();
     }
 
     folder.Unread = seen ? 0 : folder.Total;
+    var pending = UsesImap(box);
+    if (Messages.Count > 0)
+      _archive.SetLocalFlags(
+        box.Id,
+        folder.FullName,
+        Messages.Select(row => (row.Header.Id, seen, row.Header.IsFlagged)),
+        pending);
+    else
+      _archive.SetSeen(box.Id, folder.FullName, seen);
     NotifyFolderCounts();
     RefreshFolderStats();
     Status = seen ? Copy.FolderMarkedRead : Copy.FolderMarkedUnread;
-    });
+    if (session is not { IsConnected: true, SupportsFolders: true })
+      return;
+    Result result;
+    try {
+      result = await session.SetFolderSeenAsync(folder.FullName, seen, CancellationToken.None);
+    }
+    catch (OperationCanceledException) {
+      return;
+    }
+
+    if (result.IsSuccess) {
+      _archive.ClearPendingFlags(box.Id, folder.FullName, Messages.Select(row => row.Header.Id));
+      return;
+    }
+
+    if (IsSoftFlagFailure(result))
+      return;
+    foreach (var item in previous) {
+      item.row.Header.IsSeen = item.IsSeen;
+      item.row.RefreshMarks();
+    }
+
+    _archive.SetLocalFlags(
+      box.Id,
+      folder.FullName,
+      previous.Select(item => (item.row.Header.Id, item.IsSeen, item.IsFlagged)),
+      pending: false);
+    ApplyOpenedFolderCounts();
+    NotifyFolderCounts();
+    RefreshFolderStats();
+    Status = string.Join(" ", result.Messages);
   }
 
   private async Task<bool> ConfirmAsync(string title, string message) {
@@ -3561,7 +3606,9 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       }
 
       if (read.Count > 0) {
-        await session.SetMessageFlagsAsync(folder, read, new MailFlagUpdate { Seen = true }, token);
+        var stored = await session.SetMessageFlagsAsync(
+          folder, read, new MailFlagUpdate { Seen = true }, token);
+        if (stored.IsSuccess)
           _archive.UpdateFlags(
             box.Id,
             folder,
@@ -3570,7 +3617,9 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       }
 
       if (flagged.Count > 0) {
-        await session.SetMessageFlagsAsync(folder, flagged, new MailFlagUpdate { Flagged = true }, token);
+        var stored = await session.SetMessageFlagsAsync(
+          folder, flagged, new MailFlagUpdate { Flagged = true }, token);
+        if (stored.IsSuccess)
           _archive.UpdateFlags(
             box.Id,
             folder,
@@ -3624,23 +3673,16 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
         continue;
       await EnsureFoldersForRulesAsync(destBox.Id);
       foreach (var id in pair.Value) {
-        if (await CopyUidToMailboxAsync(source, sourceSession, destBox, sourceFolder, pair.Key.Folder, id, token))
+        if (!await CopyUidToMailboxAsync(source, sourceSession, destBox, sourceFolder, pair.Key.Folder, id, token))
+          continue;
+        await RemoveCopiedUidsAsync(source, sourceSession, sourceFolder, [id], token);
         copied.Add(id);
       }
     }
 
     if (copied.Count == 0)
       return;
-    var unique = copied.Distinct().ToList();
+    RemoveDroppedRows(source.Id, sourceFolder, copied.Distinct().ToList());
-    if (sourceSession is { IsConnected: true, SupportsFolders: true }) {
-      var trash = MailRetention.ResolveTrash(sourceFolders);
-      if (!string.IsNullOrWhiteSpace(trash) && !trash.Equals(sourceFolder, StringComparison.OrdinalIgnoreCase))
-        await sourceSession.MoveMessagesAsync(sourceFolder, unique, trash, token);
-      else
-        await sourceSession.SetMessageFlagsAsync(sourceFolder, unique, new MailFlagUpdate { Deleted = true }, token);
-    }
-
-    DropArchived(source.Id, sourceFolder, unique);
   }
 
   private async Task<bool> CopyUidToMailboxAsync(
@@ -3874,6 +3916,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
         if (missingFolders)
           await LoadFoldersAsync(box, live, token).ConfigureAwait(false);
         KickSyncSession(box, password);
+        await FlushPendingFlagsAsync(box).ConfigureAwait(false);
         return true;
       }
 
@@ -3904,6 +3947,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
         pst.StorePathChanged += path => PersistPstStorePath(box, path);
       await LoadFoldersAsync(box, session, token).ConfigureAwait(false);
       KickSyncSession(box, password);
+      await FlushPendingFlagsAsync(box).ConfigureAwait(false);
       await UiAsync(() => {
         EnsureIndexing(box.Id);
         NotifyFolderCommands();
@@ -3916,6 +3960,33 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     }
   }
 
+  private async Task FlushPendingFlagsAsync(MailboxAccount box) {
+    if (!UsesImap(box))
+      return;
+    var session = SessionFor(box);
+    if (session is not { IsConnected: true, SupportsFolders: true })
+      return;
+    var pending = _archive.ListAllPendingFlags(box.Id);
+    foreach (var group in pending.GroupBy(item => item.Folder, StringComparer.OrdinalIgnoreCase)) {
+      foreach (var item in group) {
+        Result result;
+        try {
+          result = await session.SetMessageFlagsAsync(
+            group.Key,
+            [item.Uid],
+            new MailFlagUpdate { Seen = item.IsSeen, Flagged = item.IsFlagged },
+            CancellationToken.None).ConfigureAwait(false);
+        }
+        catch (OperationCanceledException) {
+          return;
+        }
+
+        if (result.IsSuccess)
+          _archive.ClearPendingFlags(box.Id, group.Key, [item.Uid]);
+      }
+    }
+  }
+
   private async Task ConnectIdleMailboxesAsync() {
     foreach (var box in Mailboxes.ToList()) {
       if (SessionFor(box) is { IsConnected: true })
@@ -3936,21 +4007,24 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     }
   }
 
-  private void ApplyFolderSync(string mailboxId, string folder, MailFolderSync sync) {
+  private void ApplyFolderSync(
+    string mailboxId,
+    string folder,
+    MailFolderSync sync,
+    bool applyFlags = true) {
     if (!EnsureArchive(mailboxId))
       return;
     var ready = IsInitialSyncComplete(mailboxId);
     _archive.SetKeywordIndexEnabled(mailboxId, ready);
-    if (sync.Flags.Count > 0)
+    if (applyFlags && sync.Flags.Count > 0)
       _archive.UpdateFlags(mailboxId, folder, sync.Flags.Select(f => (f.Id, f.IsSeen, f.IsFlagged)));
-    _archive.UpsertHeaders(mailboxId, sync.Headers.Select(MailArchiveMap.FromHeader));
+    _archive.UpsertHeaders(mailboxId, sync.Headers.Select(MailArchiveMap.FromHeader), updateFlags: false);
     if (sync.Present is not null) {
       var keep = sync.Present.ToHashSet();
       var gone = _archive.Uids(mailboxId, folder).Where(uid => !keep.Contains(uid)).ToList();
       if (gone.Count > 0)
         DropArchived(mailboxId, folder, gone);
     }
-
   }
 
   private bool EnsureArchive(string mailboxId) {
@@ -4000,10 +4074,9 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       }
 
       token.ThrowIfCancellationRequested();
-      if (Volatile.Read(ref _mailEpoch) != epoch)
+      var applyFlags = Volatile.Read(ref _mailEpoch) == epoch;
-        return;
       var sync = result.Value ?? new MailFolderSync();
-      ApplyFolderSync(box.Id, folder, sync);
+      ApplyFolderSync(box.Id, folder, sync, applyFlags);
       var fresh = sync.Headers.Where(h => !known.Contains(h.Id)).ToList();
       if (known.Count > 0) {
         await UiAsync(() => {
@@ -4325,11 +4398,14 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     StoreArchivedBody(box.Id, header, body);
     await Dispatcher.UIThread.InvokeAsync(async () => {
       MarkRowAttachments(header);
-      if (SelectedMessage is null
+      var stillSelected = SelectedMessage is not null
-          || SelectedMessage.Header.Id != header.Id
+        && SelectedMessage.Header.Id == header.Id
-          || !SelectedMessage.Header.Folder.Equals(header.Folder, StringComparison.OrdinalIgnoreCase)) {
+        && SelectedMessage.Header.Folder.Equals(header.Folder, StringComparison.OrdinalIgnoreCase);
+      if (!stillSelected) {
         if (Status == Copy.OpeningMessage)
           Status = "";
+        // Body finished after the user moved on — still keep the Seen mark.
+        await MarkOpenedReadAsync(header).ConfigureAwait(true);
         return;
       }
 
@@ -4353,7 +4429,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
           Status = explain;
       }
 
-      await MarkOpenedReadAsync(header, token).ConfigureAwait(true);
+      await MarkOpenedReadAsync(header).ConfigureAwait(true);
       if (_pendingWindow is { } pending
           && pending.Header.Id == header.Id
           && pending.Header.Folder.Equals(header.Folder, StringComparison.OrdinalIgnoreCase)) {
@@ -4387,7 +4463,7 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     MessageWindowRequested?.Invoke(vm);
   }
 
-  private async Task MarkOpenedReadAsync(MailMessageHeader header, CancellationToken token) {
+  private async Task MarkOpenedReadAsync(MailMessageHeader header) {
     var row = Messages.FirstOrDefault(m =>
       m.Header.Id == header.Id
       && m.Header.Folder.Equals(header.Folder, StringComparison.OrdinalIgnoreCase));
@@ -4405,30 +4481,54 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     var flagged = row.Header.IsFlagged;
     row.Header.IsSeen = true;
     row.RefreshMarks();
+    var pending = box is not null && UsesImap(box);
     if (box is not null)
-      _archive.UpdateFlags(box.Id, folder, [(row.Header.Id, true, flagged)]);
+      _archive.SetLocalFlags(box.Id, folder, [(row.Header.Id, true, flagged)], pending);
     NotifyFolderCounts();
     RefreshFolderStats();
     var session = SessionFor(box);
-    if (session is not { SupportsFolders: true })
+    if (session is not { IsConnected: true, SupportsFolders: true })
       return;
-    var result = await session.SetMessageFlagsAsync(
+    Result result;
+    try {
+      result = await session.SetMessageFlagsAsync(
         folder,
         [row.Header.Id],
         new MailFlagUpdate { Seen = true },
-      token).ConfigureAwait(true);
+        CancellationToken.None).ConfigureAwait(true);
-    if (result.IsSuccess)
+    }
+    catch (OperationCanceledException) {
+      return;
+    }
+
+    if (result.IsSuccess) {
+      if (box is not null)
+        _archive.ClearPendingFlags(box.Id, folder, [row.Header.Id]);
+      return;
+    }
+
+    if (IsSoftFlagFailure(result))
       return;
     if (folderRow is not null)
       ApplyUnreadDelta(folderRow, [row], false);
     row.Header.IsSeen = false;
     row.RefreshMarks();
     if (box is not null)
-      _archive.UpdateFlags(box.Id, folder, [(row.Header.Id, false, flagged)]);
+      _archive.SetLocalFlags(box.Id, folder, [(row.Header.Id, false, flagged)], pending: false);
     NotifyFolderCounts();
     RefreshFolderStats();
   }
 
+  private static bool IsSoftFlagFailure(Result result) {
+    foreach (var message in result.Messages) {
+      if (message.Contains("Not connected", StringComparison.OrdinalIgnoreCase)
+          || message.Contains("cancel", StringComparison.OrdinalIgnoreCase))
+        return true;
+    }
+
+    return false;
+  }
+
   private void ApplyReading(MailMessageBody body, bool keepKind = false) {
     var inner = UnwrapEnvelope && body.Envelope.HasInnerMessage;
     ReadingSubject = inner && !string.IsNullOrWhiteSpace(body.InnerSubject)
@@ -4987,7 +5087,9 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
       NoteUiMailChange();
       var copied = new List<uint>();
       foreach (var id in ids) {
-        if (await CopyUidToMailboxAsync(sourceBox, sourceSession, destBox, source, dest, id, token))
+        if (!await CopyUidToMailboxAsync(sourceBox, sourceSession, destBox, source, dest, id, token))
+          continue;
+        await RemoveCopiedUidsAsync(sourceBox, sourceSession, source, [id], token);
         copied.Add(id);
       }
 
@@ -4996,7 +5098,6 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
         return;
       }
 
-      await RemoveCopiedUidsAsync(sourceBox, sourceSession, source, copied, token);
       ApplyFolderMoveCounts(sourceBox, destBox, source, dest, copied.Count, rows);
       RemoveDroppedRows(sourceBox.Id, source, copied);
       await LoadFoldersAsync(destBox, destSession, token);
@@ -5121,20 +5222,25 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
     var targets = rows ?? TargetRows();
     if (targets.Count == 0)
       return false;
-    var ok = false;
+    var ok = true;
-    await RunAsync(Copy.UpdatingFlags, async token => {
+    Status = Copy.UpdatingFlags;
     foreach (var group in targets.GroupBy(row => MailMessageKey.Of(row.MailboxId, row.Header.Folder, 0))) {
       var box = MailboxById(group.Key.MailboxId) ?? SelectedMailbox;
       var session = SessionFor(box);
-        if (session is not { SupportsFolders: true }) {
+      var folder = group.Key.Folder;
+      var groupRows = group.ToList();
+      var previous = groupRows
+        .Select(row => (row, row.Header.IsSeen, row.Header.IsFlagged, row.Header.Priority))
+        .ToList();
+      var remote = session is { SupportsFolders: true };
+      var pending = box is not null && UsesImap(box) && !update.Deleted;
+      if (!remote && box is null) {
         Status = Copy.Connecting;
-          return;
+        ok = false;
+        continue;
       }
 
       NoteUiMailChange();
-        var folder = group.Key.Folder;
-        var groupRows = group.ToList();
-        var previous = groupRows.Select(row => (row, row.Header.IsSeen, row.Header.IsFlagged)).ToList();
       if (update.Seen is { } seen && SelectedFolder is { } current
           && current.FullName.Equals(folder, StringComparison.OrdinalIgnoreCase))
         ApplyUnreadDelta(current, groupRows, seen);
@@ -5143,46 +5249,72 @@ public partial class MainViewModel : ObservableObject, IAsyncDisposable {
           apply(row);
           row.RefreshMarks();
         }
-
-          if (box is not null)
-            _archive.UpdateFlags(
-              box.Id,
-              folder,
-              groupRows.Select(r => (r.Header.Id, r.Header.IsSeen, r.Header.IsFlagged)));
       }
 
+      if (box is not null && apply is not null)
+        _archive.SetLocalFlags(
+          box.Id,
+          folder,
+          groupRows.Select(r => (r.Header.Id, r.Header.IsSeen, r.Header.IsFlagged)),
+          pending);
       NotifyFolderCounts();
       RefreshFolderStats();
-        var result = await session.SetMessageFlagsAsync(
+      if (!remote || session is null) {
+        if (apply is not null)
+          continue;
+        Status = Copy.Connecting;
+        ok = false;
+        continue;
+      }
+
+      Result result;
+      try {
+        result = await session.SetMessageFlagsAsync(
           folder,
           TargetIds(groupRows),
           update,
-          token).ConfigureAwait(true);
+          CancellationToken.None).ConfigureAwait(true);
-        if (result.IsSuccess)
+      }
+      catch (OperationCanceledException) {
         continue;
+      }
+
+      if (result.IsSuccess) {
+        if (box is not null && pending)
+          _archive.ClearPendingFlags(box.Id, folder, TargetIds(groupRows));
+        continue;
+      }
+
+      if (IsSoftFlagFailure(result) || update.Deleted) {
+        if (!result.IsSuccess && update.Deleted)
+          ok = false;
+        continue;
+      }
+
       foreach (var item in previous) {
         item.row.Header.IsSeen = item.IsSeen;
         item.row.Header.IsFlagged = item.IsFlagged;
+        item.row.Header.Priority = item.Priority;
         item.row.RefreshMarks();
       }
 
-        if (box is not null)
+      if (box is not null && apply is not null)
-          _archive.UpdateFlags(
+        _archive.SetLocalFlags(
           box.Id,
           folder,
-            previous.Select(item => (item.row.Header.Id, item.IsSeen, item.IsFlagged)));
+          previous.Select(item => (item.row.Header.Id, item.IsSeen, item.IsFlagged)),
+          pending: false);
       if (SelectedFolder is { } open
           && open.FullName.Equals(folder, StringComparison.OrdinalIgnoreCase))
         ApplyOpenedFolderCounts();
       NotifyFolderCounts();
       RefreshFolderStats();
       Status = string.Join(" ", result.Messages);
-        return;
+      ok = false;
     }
 
+    if (ok)
       Status = "Updated.";
-      ok = true;
-    });
     return ok;
   }