Phase 2.2: AppSettings.AutoUpdate / UpdateCheckCadence / IncludePreReleases + Updates dialog section

Adds the three persisted settings the Phase 2.3 banner UI and Phase 3 release pipeline will read, and a 'Updates' section to the Settings dialog so users can opt in or out before the auto-update channel goes live for real users in Phase 3. Schema v6 -> v7 (no-op migration; all three fields have safe defaults).

Defaults diverge from the master plan: AutoUpdate defaults to NotifyOnly, not Automatic. NotifyOnly is the safer choice for a tool that's used by developers who deserve to know when their binary changes under them. The runtime distinction between NotifyOnly and Disabled (NotifyOnly = check + show banner, don't auto-apply) requires the banner UI from Phase 2.3 — until then, both modes short-circuit the App.xaml.cs startup check identically. The user opt-in path through the new Settings dialog section means Phase 3 can ship safely without users being surprise-auto-updated.

Phase 2.2 also doesn't wire UpdateCheckCadence (no periodic timer exists yet — that's Phase 2.3) or IncludePreReleases (VelopackUpdateService hardcodes prerelease: false — also Phase 2.3). Inert settings are flagged in their XML docs so the gap is discoverable.

App.xaml.cs gains one branch around the fire-and-forget background check: AutoUpdate==Automatic still does Phase 2.1's silent download + WaitExitThenApplyUpdates; anything else (NotifyOnly, Disabled) is a no-op until Phase 2.3 differentiates them.

Settings dialog new section follows the existing PR-review section visual conventions (SectionHeader + FieldLabel + ComboBox / CheckBox). ComboBoxes display the raw enum name (StartupOnly, EverySixHours, etc.) — adding a value converter for friendlier display is a Phase 2.3 polish task.

Tests: 1371 passing (+2: v6 -> v7 migration test follows the v4 -> v5 / v5 -> v6 pattern; round-trip test confirms serializer reads back what it writes). 0 warnings, 0 errors in dotnet build -c Release. CHANGELOG [Unreleased] documents the new dialog section.

AI-Local-Session: 4519f6b6-393a-4476-8efa-410e5396c3a9

AI-Cloud-Session: 72f9e474-60ab-42c2-b2a0-28fee827cbbb

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: Geeven Singh

CHANGELOG.md

@@ -12,6 +12,29 @@ body. Keep section headings exact and write notes in Markdown.
 
 ## [Unreleased]
 
+### Added
+
+- **Settings → Updates section.** Three new settings control how
+  DiffViewer handles available updates from GitHub Releases. The
+  settings are inert on portable / from-source builds (those have
+  never checked for updates) and become live when the upcoming
+  Velopack-installed channel ships:
+  - **Auto-update behavior** — `NotifyOnly` (default for new and
+    migrated installs), `Automatic`, or `Disabled`. `NotifyOnly`
+    is the safe default: silent auto-updates are opt-in. The
+    banner UX that distinguishes `NotifyOnly` from `Disabled` lands
+    in a follow-up.
+  - **Check frequency** — `StartupOnly` / `Hourly` / `EverySixHours`
+    / `Daily` (default) / `Weekly`. Currently only the startup
+    check fires; the periodic timer that honors this setting lands
+    in a follow-up.
+  - **Include pre-release versions** — off by default. Currently
+    ignored (the update check is hardcoded stable-only); will be
+    wired through to the Velopack source in a follow-up.
+- `settings.json` schema bump v6 → v7. The migration is a no-op:
+  all three new fields default to safe values, so pre-v7 files load
+  with the same effective behaviour they had before.
+
 ## [1.4.0] - 2026-05-29
 
 ### Changed

DiffViewer.Tests/Services/SettingsServiceTests.cs

@@ -498,6 +498,56 @@ public void Load_V5File_MigratesToV6_RenderSvgImageDefaultsToTrue()
         svc.Current.RenderSvgImage.Should().BeTrue();
     }
 
+    [Fact]
+    public void Load_V6File_MigratesToV7_AutoUpdateFieldsHydrateToDefaults()
+    {
+        // v6 schema (current minus 1) had no auto-update fields.
+        // After v6->v7 migration the three fields should hydrate to
+        // their safe defaults (NotifyOnly / Daily / false) and other
+        // fields should be preserved. Phase 2.2 deliberately defaults
+        // AutoUpdate to NotifyOnly so existing installs do not opt
+        // into silent updates without explicit user consent.
+        var v6 = new JsonObject
+        {
+            ["schemaVersion"] = 6,
+            ["fontSize"] = 19,
+            ["tabWidth"] = 7,
+            ["isSideBySide"] = false,
+            ["renderSvgImage"] = false,
+        };
+        File.WriteAllText(_settingsPath, v6.ToJsonString());
+
+        var svc = new SettingsService(_settingsPath);
+
+        svc.LastLoadOutcome.Should().Be(SettingsLoadOutcome.Migrated);
+        svc.Current.FontSize.Should().Be(19);
+        svc.Current.TabWidth.Should().Be(7);
+        svc.Current.IsSideBySide.Should().BeFalse();
+        svc.Current.RenderSvgImage.Should().BeFalse();
+        svc.Current.AutoUpdate.Should().Be(AutoUpdateMode.NotifyOnly);
+        svc.Current.UpdateCheckCadence.Should().Be(UpdateCheckCadence.Daily);
+        svc.Current.IncludePreReleases.Should().BeFalse();
+    }
+
+    [Fact]
+    public void Save_Then_Load_RoundTripsAutoUpdateFields()
+    {
+        var svc1 = new SettingsService(_settingsPath);
+        svc1.Save(svc1.Current with
+        {
+            AutoUpdate = AutoUpdateMode.Disabled,
+            UpdateCheckCadence = UpdateCheckCadence.Weekly,
+            IncludePreReleases = true,
+        });
+
+        var svc2 = new SettingsService(_settingsPath);
+
+        svc2.LastLoadOutcome.Should().Be(SettingsLoadOutcome.Loaded);
+        svc2.Current.AutoUpdate.Should().Be(AutoUpdateMode.Disabled);
+        svc2.Current.UpdateCheckCadence.Should().Be(UpdateCheckCadence.Weekly);
+        svc2.Current.IncludePreReleases.Should().BeTrue();
+    }
+
     [Fact]
     public void RepoUrlMappings_StableOrderingOnDisk_AcrossSaves()
     {

DiffViewer/App.xaml.cs

@@ -1,8 +1,10 @@
 using System;
+using System.IO;
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Windows;
+using DiffViewer.Models;
 using DiffViewer.Rendering;
 using DiffViewer.Services;
 using DiffViewer.Utility;
@@ -168,19 +170,25 @@ protected override async void OnStartup(StartupEventArgs e)
 
         window.Show();
 
-        // Auto-update lifecycle (Phase 2.1). Fires a single background
-        // check at startup; if an update is available it downloads
-        // and queues to apply silently on the next clean exit.
-        // Velopack-installed copies get the real service; portable /
-        // dev launches get a no-op. Phase 2.2 will add periodic
-        // re-checks driven by a configurable interval; Phase 2.3 will
-        // add the in-app notification banner that turns this silent
-        // path into a user-visible one.
-        IUpdateService updateService =
-            VelopackUpdateService.TryCreateForInstalled()
-                ?? (IUpdateService)new NullUpdateService();
-        var updateCt = _shutdownCts.Token;
-        _ = Task.Run(() => updateService.CheckAndQueueUpdateAsync(updateCt));
+        // Auto-update lifecycle (Phase 2.1 + 2.2). Fires a single
+        // background check at startup IF the user has opted in via
+        // AppSettings.AutoUpdate; Phase 2.2 defaults to NotifyOnly so
+        // no check fires for new installs until either the user flips
+        // the setting or Phase 2.3 redefines NotifyOnly to mean
+        // "check + show banner, don't apply silently." For now,
+        // anything other than AutoUpdateMode.Automatic short-circuits
+        // here. Velopack-installed copies get the real service;
+        // portable / dev launches get a no-op. Phase 2.3 will add the
+        // banner UI; Phase 3 will start producing Velopack-installed
+        // copies in the wild.
+        if (settingsService.Current.AutoUpdate == AutoUpdateMode.Automatic)
+        {
+            IUpdateService updateService =
+                VelopackUpdateService.TryCreateForInstalled()
+                    ?? (IUpdateService)new NullUpdateService();
+            var updateCt = _shutdownCts.Token;
+            _ = Task.Run(() => updateService.CheckAndQueueUpdateAsync(updateCt));
+        }
     }
 
     protected override void OnExit(ExitEventArgs e)

DiffViewer/Models/AppSettings.cs

@@ -16,7 +16,7 @@ namespace DiffViewer.Models;
 public sealed record AppSettings
 {
     /// <summary>Current schema version; bump every time the shape changes.</summary>
-    public const int CurrentSchemaVersion = 6;
+    public const int CurrentSchemaVersion = 7;
 
     public int SchemaVersion { get; init; } = CurrentSchemaVersion;
 
@@ -111,6 +111,34 @@ public sealed record AppSettings
     /// </summary>
     public IReadOnlyDictionary<RepoUrlKey, string> RepoUrlMappings { get; init; }
         = new Dictionary<RepoUrlKey, string>();
+
+    // ---- Auto-update (added in v7) ----
+    /// <summary>
+    /// How DiffViewer handles available updates from the configured
+    /// update source. Default <see cref="AutoUpdateMode.NotifyOnly"/>
+    /// — silent auto-updates are opt-in. See
+    /// <see cref="AutoUpdateMode"/> for the per-value semantics and
+    /// the cross-phase rollout story.
+    /// </summary>
+    public AutoUpdateMode AutoUpdate { get; init; } = AutoUpdateMode.NotifyOnly;
+
+    /// <summary>
+    /// How often the update check fires. Default
+    /// <see cref="UpdateCheckCadence.Daily"/>. Inert in Phase 2.2
+    /// (only the startup check exists); Phase 2.3 wires a periodic
+    /// timer that honors this value.
+    /// </summary>
+    public UpdateCheckCadence UpdateCheckCadence { get; init; } = UpdateCheckCadence.Daily;
+
+    /// <summary>
+    /// When <c>true</c>, the update source includes pre-release tags
+    /// (e.g. <c>v1.5.0-rc1</c>). Default <c>false</c> — stable
+    /// releases only. Inert in Phase 2.2 (the Velopack adapter
+    /// hardcodes <c>prerelease: false</c>); Phase 2.3 will read this
+    /// and pass it through to
+    /// <see cref="Velopack.Sources.GithubSource"/>.
+    /// </summary>
+    public bool IncludePreReleases { get; init; }
 }
 
 /// <summary>

DiffViewer/Models/AutoUpdateMode.cs

@@ -0,0 +1,31 @@
+namespace DiffViewer.Models;
+
+/// <summary>
+/// How DiffViewer handles available updates from the configured update
+/// source. Persisted as <c>AppSettings.AutoUpdate</c> in
+/// <c>settings.json</c>; added in schema v7. The runtime effect of
+/// each value evolves across phases of the auto-update rollout:
+///
+/// <list type="bullet">
+///   <item><see cref="Automatic"/>: download new releases in the
+///     background and apply them silently on the next clean exit.
+///     Phase 2.3 will add a banner to surface "update available";
+///     until then, this mode is fully silent.</item>
+///   <item><see cref="NotifyOnly"/>: <b>Phase 2.2</b> — effectively
+///     the same as <see cref="Disabled"/> (no banner UI exists yet
+///     to surface notifications); <b>Phase 2.3 onward</b> — check,
+///     download, but only apply when the user clicks the banner's
+///     "install" action. The default for new installs.</item>
+///   <item><see cref="Disabled"/>: skip the update check entirely.
+///     Useful for tightly-controlled environments where updates are
+///     managed externally, or users who prefer to drive their own
+///     upgrade cadence by downloading new installers from the
+///     Releases page.</item>
+/// </list>
+/// </summary>
+public enum AutoUpdateMode
+{
+    Automatic,
+    NotifyOnly,
+    Disabled,
+}

DiffViewer/Models/UpdateCheckCadence.cs

@@ -0,0 +1,26 @@
+namespace DiffViewer.Models;
+
+/// <summary>
+/// How often DiffViewer should poll the configured update source for
+/// a newer release. Persisted as
+/// <c>AppSettings.UpdateCheckCadence</c> in <c>settings.json</c>;
+/// added in schema v7. Inert in Phase 2.2 — only the startup-time
+/// check fires today, regardless of this setting. Phase 2.3 will add
+/// a periodic re-check timer that honors the configured cadence.
+///
+/// <para>The five values cover the documented choices from the auto-update
+/// design ("startup-only / 1h / 6h / 24h / 7d"). DiffViewer launches
+/// are deliberate (it's not a chat client), so anything more frequent
+/// than <see cref="Hourly"/> would be wasted polling against GitHub
+/// rate limits.</para>
+/// </summary>
+public enum UpdateCheckCadence
+{
+    /// <summary>Only check at startup; no periodic re-check.</summary>
+    StartupOnly,
+
+    Hourly,
+    EverySixHours,
+    Daily,
+    Weekly,
+}

DiffViewer/Services/SettingsJsonSerializer.cs

@@ -55,6 +55,9 @@ public static string Serialize(AppSettings s)
             ["repoRoots"] = SerializeStringList(s.RepoRoots),
             ["defaultCloneDestination"] = s.DefaultCloneDestination,
             ["repoUrlMappings"] = SerializeRepoUrlMappings(s.RepoUrlMappings),
+            ["autoUpdate"] = s.AutoUpdate.ToString(),
+            ["updateCheckCadence"] = s.UpdateCheckCadence.ToString(),
+            ["includePreReleases"] = s.IncludePreReleases,
         };
         return obj.ToJsonString(WriteOptions);
     }
@@ -89,6 +92,9 @@ public static AppSettings Deserialize(JsonObject obj)
             RepoRoots = DeserializeStringList(obj["repoRoots"]) ?? defaults.RepoRoots,
             DefaultCloneDestination = TryString(obj, "defaultCloneDestination"),
             RepoUrlMappings = DeserializeRepoUrlMappings(obj["repoUrlMappings"]) ?? defaults.RepoUrlMappings,
+            AutoUpdate = TryEnum<AutoUpdateMode>(obj, "autoUpdate") ?? defaults.AutoUpdate,
+            UpdateCheckCadence = TryEnum<UpdateCheckCadence>(obj, "updateCheckCadence") ?? defaults.UpdateCheckCadence,
+            IncludePreReleases = TryBool(obj, "includePreReleases") ?? defaults.IncludePreReleases,
         };
     }
 

DiffViewer/Services/SettingsMigrations.cs

@@ -37,6 +37,15 @@ namespace DiffViewer.Services;
 /// because the field has a sensible default (<c>true</c>) — pre-v6
 /// files deserialize with the rasterised view enabled, matching the
 /// headline behaviour the feature was designed to deliver.</para>
+///
+/// <para>v7 introduced the three auto-update settings:
+/// <c>autoUpdate</c> (<see cref="AutoUpdateMode"/>),
+/// <c>updateCheckCadence</c> (<see cref="UpdateCheckCadence"/>), and
+/// <c>includePreReleases</c>. The migration is a no-op because every
+/// field has a safe default — pre-v7 files deserialize to
+/// <see cref="AutoUpdateMode.NotifyOnly"/> / <see cref="UpdateCheckCadence.Daily"/> /
+/// <c>false</c>, which exactly reflects the "no auto-update opted into yet"
+/// posture Phase 2.2 ships with.</para>
 /// </summary>
 internal static class SettingsMigrations
 {
@@ -58,6 +67,7 @@ public static JsonObject MigrateUpTo(JsonObject obj, int fromVersion, int toVers
                 3 => MigrateV3ToV4, // adds fileListPaneWidthPixels (double, default 320)
                 4 => MigrateV4ToV5, // adds repoRoots, defaultCloneDestination, repoUrlMappings (all defaultable)
                 5 => MigrateV5ToV6, // adds renderSvgImage (bool, default true)
+                6 => MigrateV6ToV7, // adds autoUpdate / updateCheckCadence / includePreReleases (all defaultable)
                 _ => throw new InvalidOperationException($"No migration registered from version {v} to {v + 1}."),
             };
             current = step(current);
@@ -116,4 +126,14 @@ public static JsonObject MigrateUpTo(JsonObject obj, int fromVersion, int toVers
     /// <see cref="AppSettings.RenderSvgImage"/> as <c>true</c>.
     /// </summary>
     private static JsonObject MigrateV5ToV6(JsonObject obj) => obj;
+
+    /// <summary>
+    /// v7 adds the three auto-update settings (<c>autoUpdate</c>,
+    /// <c>updateCheckCadence</c>, <c>includePreReleases</c>). All have
+    /// safe defaults that map to "no auto-update opted into yet" so
+    /// the migration is a no-op; the deserializer fills in
+    /// <see cref="AutoUpdateMode.NotifyOnly"/> /
+    /// <see cref="UpdateCheckCadence.Daily"/> / <c>false</c>.
+    /// </summary>
+    private static JsonObject MigrateV6ToV7(JsonObject obj) => obj;
 }

DiffViewer/ViewModels/SettingsViewModel.cs

@@ -120,6 +120,17 @@ public SettingsViewModel(
     partial void OnDefaultCloneDestinationChanged(string value) =>
         OnPropertyChanged(nameof(HasDefaultCloneDestination));
 
+    // Auto-update settings (v7)
+    [ObservableProperty] private AutoUpdateMode _autoUpdate = AutoUpdateMode.NotifyOnly;
+    [ObservableProperty] private UpdateCheckCadence _updateCheckCadence = UpdateCheckCadence.Daily;
+    [ObservableProperty] private bool _includePreReleases;
+
+    /// <summary>Option list for the AutoUpdate dropdown in the dialog.</summary>
+    public IReadOnlyList<AutoUpdateMode> AutoUpdateOptions { get; } = Enum.GetValues<AutoUpdateMode>();
+
+    /// <summary>Option list for the UpdateCheckCadence dropdown in the dialog.</summary>
+    public IReadOnlyList<UpdateCheckCadence> UpdateCheckCadenceOptions { get; } = Enum.GetValues<UpdateCheckCadence>();
+
     // Status line
     [ObservableProperty] private string _statusMessage = string.Empty;
 
@@ -225,6 +236,15 @@ partial void OnConfirmRevertHunkChanged(bool value) =>
     partial void OnConfirmDeleteFileChanged(bool value) =>
         SaveIfNotSuppressed(s => s with { SuppressDeleteFileConfirmation = !value });
 
+    partial void OnAutoUpdateChanged(AutoUpdateMode value) =>
+        SaveIfNotSuppressed(s => s with { AutoUpdate = value });
+
+    partial void OnUpdateCheckCadenceChanged(UpdateCheckCadence value) =>
+        SaveIfNotSuppressed(s => s with { UpdateCheckCadence = value });
+
+    partial void OnIncludePreReleasesChanged(bool value) =>
+        SaveIfNotSuppressed(s => s with { IncludePreReleases = value });
+
     partial void OnSelectedColorPresetChanged(ColorSchemePresetName value)
     {
         if (_suppress) return;
@@ -411,6 +431,10 @@ private void LoadFromSettings()
             ConfirmRevertHunk = !s.SuppressRevertHunkConfirmation;
             ConfirmDeleteFile = !s.SuppressDeleteFileConfirmation;
 
+            AutoUpdate = s.AutoUpdate;
+            UpdateCheckCadence = s.UpdateCheckCadence;
+            IncludePreReleases = s.IncludePreReleases;
+
             RepoRoots.Clear();
             foreach (var root in s.RepoRoots) RepoRoots.Add(root);
 

DiffViewer/Views/SettingsDialog.xaml

@@ -272,6 +272,40 @@
                            Visibility="{Binding RepoUrlMappings.Count,
                                                 Converter={x:Static vm:ZeroToVisibleConverter.Instance}}"
                            Text="No remembered clones yet."/>
+
+                <!-- Updates (added in v7) -->
+                <TextBlock Text="Updates" Style="{StaticResource SectionHeader}"/>
+                <TextBlock Margin="0,0,0,6" Foreground="#666" TextWrapping="Wrap" FontStyle="Italic">
+                    DiffViewer can check GitHub Releases for a newer version. The check
+                    only runs when launched from a Velopack-installed copy; portable
+                    builds ignore these settings.
+                </TextBlock>
+
+                <Grid Margin="0,2">
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="160"/>
+                        <ColumnDefinition Width="*"/>
+                    </Grid.ColumnDefinitions>
+                    <Grid.RowDefinitions>
+                        <RowDefinition/><RowDefinition/><RowDefinition/>
+                    </Grid.RowDefinitions>
+
+                    <TextBlock Grid.Row="0" Grid.Column="0" Style="{StaticResource FieldLabel}"
+                               Text="Auto-update behavior"/>
+                    <ComboBox  Grid.Row="0" Grid.Column="1" Margin="0,4"
+                               ItemsSource="{Binding AutoUpdateOptions}"
+                               SelectedItem="{Binding AutoUpdate}"/>
+
+                    <TextBlock Grid.Row="1" Grid.Column="0" Style="{StaticResource FieldLabel}"
+                               Text="Check frequency"/>
+                    <ComboBox  Grid.Row="1" Grid.Column="1" Margin="0,4"
+                               ItemsSource="{Binding UpdateCheckCadenceOptions}"
+                               SelectedItem="{Binding UpdateCheckCadence}"/>
+
+                    <CheckBox  Grid.Row="2" Grid.Column="1" Margin="0,6,0,0"
+                               Content="Include pre-release versions"
+                               IsChecked="{Binding IncludePreReleases}"/>
+                </Grid>
             </StackPanel>
         </ScrollViewer>
     </DockPanel>