Squashed commit of the following:

commit 44803e06d1aa45496c04127930aa8897272d42f6
Author: vnugent <public@vaughnnugent.com>
Date:   Mon Apr 8 21:41:38 2024 -0400

    fix: dangling/expired session security check and cookie cleanup

commit 1082bd146549a1aff47877bcd28e6be1ce0ef5e9
Author: vnugent <public@vaughnnugent.com>
Date:   Sat Mar 30 22:20:29 2024 -0400

    feat(app): Add AppData client plugin and browser library updated

commit ec9b42f4cacbeae8a0b4d96e48bd9e522b3a9145
Merge: 2a11454 27b487b
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Mar 24 21:16:05 2024 -0400

    Merge branch 'master' into develop

commit 2a114541a3bfddae887adaa98c1ed326b125d511
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Mar 24 20:53:38 2024 -0400

    refactor: pull apart session authorization for future dev

commit f8aea6453ddb2d56c1ce2ecb6a9e67d1af523c2e
Author: vnugent <public@vaughnnugent.com>
Date:   Thu Mar 21 14:33:21 2024 -0400

    feat: Add optional svg base64 icons for social OAuth2 connections

commit cc29bed99dc9e151315cce75e50d55dca306b532
Author: vnugent <public@vaughnnugent.com>
Date:   Sun Mar 10 21:58:27 2024 -0400

    source tree project location updated

1 files changed, 75 insertions, 0 deletions

diff --git a/plugins/VNLib.Plugins.Essentials.Accounts.AppData/src/Model/HttpExtensions.cs b/plugins/VNLib.Plugins.Essentials.Accounts.AppData/src/Model/HttpExtensions.cs
new file mode 100644
index 0000000..9628b79
--- /dev/null
+++ b/plugins/VNLib.Plugins.Essentials.Accounts.AppData/src/Model/HttpExtensions.cs
@@ -0,0 +1,75 @@
+/*
+* Copyright (c) 2024 Vaughn Nugent
+* 
+* Library: VNLib
+* Package: VNLib.Plugins.Essentials.Accounts.AppData
+* File: HttpExtensions.cs 
+*
+* HttpExtensions.cs is part of VNLib.Plugins.Essentials.Accounts.AppData which 
+* is part of the larger VNLib collection of libraries and utilities.
+*
+* VNLib.Plugins.Essentials.Accounts is free software: you can redistribute it and/or modify 
+* it under the terms of the GNU Affero General Public License as 
+* published by the Free Software Foundation, either version 3 of the
+* License, or (at your option) any later version.
+*
+* VNLib.Plugins.Essentials.Accounts is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+* GNU Affero General Public License for more details.
+*
+* You should have received a copy of the GNU Affero General Public License
+* along with this program.  If not, see https://www.gnu.org/licenses/.
+*/
+
+using System;
+using System.Net;
+
+using VNLib.Net.Http;
+
+namespace VNLib.Plugins.Essentials.Accounts.AppData.Model
+{
+    internal static class HttpExtensions
+    {
+        const string ChecksumHeader = "X-Data-Checksum";
+
+        public static void SetRecordResponse(this HttpEntity entity, UserRecordData record, HttpStatusCode code)
+        {
+            //Set checksum header
+            entity.Server.Headers.Append(ChecksumHeader, $"{record.Checksum}");
+
+            //Set the response to a new memory reader with the record data
+            entity.CloseResponse(
+                code, 
+                ContentType.Binary,
+                new BinDataRecordReader(record.Data)
+            );
+        }
+
+        public static ulong? GetUserDataChecksum(this IConnectionInfo server)
+        {
+            string? checksumStr = server.Headers[ChecksumHeader];
+            return string.IsNullOrWhiteSpace(checksumStr) && ulong.TryParse(checksumStr, out ulong checksum) ? checksum : null;
+        }
+
+        sealed class BinDataRecordReader(byte[] recordData) : IMemoryResponseReader
+        {
+            private int _read;
+
+            ///<inheritdoc/>
+            public int Remaining => recordData.Length - _read;
+
+            ///<inheritdoc/>
+            public void Advance(int written) => _read += written;
+
+            ///<inheritdoc/>
+            public void Close()
+            {
+                //No-op
+            }
+
+            ///<inheritdoc/>
+            public ReadOnlyMemory<byte> GetMemory() => recordData.AsMemory(_read);
+        }
+    }
+}