Phase 2.4: periodic re-check timer + skip-this-version + friendly enum labels

Closes out the 2.x sub-phase sequence. Three independent polish items that finish wiring the three settings AppSettings introduced in 2.2 and complete the banner UX 2.3 started.

Periodic re-check timer: UpdateNotificationViewModel now schedules a DispatcherTimer after each Check / Dismiss / Skip, with the interval driven by AppSettings.UpdateCheckCadence. StartupOnly opts out entirely. If the banner is still visible at tick time the recheck is skipped (user is still looking at a previous notification). Tests cover the pure cadence->TimeSpan mapping (UpdateCheckCadenceExtensions); the DispatcherTimer integration itself stays untested per the §10 view-wiring carve-out and the constructor takes a useDispatcherTimer flag so VM tests opt out.

Skip-this-version persistence: AppSettings.SkippedUpdateVersion (nullable string) added in schema v8 with no-op migration. UpdateNotificationViewModel reads it at check time and short-circuits if the detected version matches; the new SkipCommand writes the pending version via the setSkippedVersion callback. Banner gains a third button ('Skip this version'). Skip is per-version: detecting a newer version overwrites the previous skip and surfaces the banner again.

Friendly enum labels in the Settings dialog: new generic EnumDisplayConverter maps AutoUpdateMode and UpdateCheckCadence values to user-facing strings ('Every six hours', 'Notify only (show banner)', etc.). Wired via ItemTemplate on the Updates section's ComboBoxes.

VM constructor signature grew: now takes Func<UpdateCheckCadence>, Func<string?>, Action<string?> alongside the existing Func<AutoUpdateMode>. App.OnStartup hands each one a closure over settingsService.Current.* and settingsService.Update so live setting changes take effect on the next check / skip without recreating the VM. Tests share a NewVm() helper to keep call sites readable.

Tests: 1403 passing (+22). Breakdown: 5 UpdateCheckCadenceExtensions, 11 EnumDisplayConverter, 4 new UpdateNotificationViewModel (skip-match / skip-differ / SkipCommand x2), 2 SettingsService (v7->v8 migration + skip round-trip). 0 warnings, 0 errors in dotnet build -c Release. CHANGELOG [Unreleased] documents the new banner button and the timer.

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

@@ -14,6 +14,17 @@ body. Keep section headings exact and write notes in Markdown.
 
 ### Added
 
+- **Auto-update banner gets a "Skip this version" button.** Persists
+  the skipped version into `settings.json` so future checks for the
+  same version stay quiet across launches. Detection of a newer
+  version overwrites the previous skip and shows the banner again.
+- **Periodic re-check timer for auto-updates.** Driven by the
+  Settings → Updates → "Check frequency" dropdown (StartupOnly /
+  Hourly / Every six hours / Daily / Weekly). `StartupOnly` opts
+  out of periodic checks entirely; the others schedule a re-check
+  after each `Check`/`Dismiss`/`Skip`. If the banner is still
+  visible at tick time the recheck is skipped (the user is still
+  looking at a previous notification).
 - **Auto-update banner at the top of the main window.** Replaces
   the silent placeholder from the previous Phase 2.1 / 2.2
   iterations:
@@ -23,9 +34,8 @@ body. Keep section headings exact and write notes in Markdown.
   - In `NotifyOnly` mode (the default), the banner appears as soon
     as an update is detected, with an **Install** button that
     triggers the download + apply-on-next-launch sequence.
-  - Either mode's banner has a **Dismiss** button that hides it
-    for the rest of the session. (A persistent "skip this
-    version" gesture is planned as a follow-up.)
+  - Either mode's banner has **Dismiss** (session-scoped) and
+    **Skip this version** (persists) buttons.
 - **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
@@ -35,14 +45,14 @@ body. Keep section headings exact and write notes in Markdown.
     migrated installs), `Automatic`, or `Disabled`. `NotifyOnly`
     is the safe default: silent auto-updates are opt-in.
   - **Check frequency** — `StartupOnly` / `Hourly` / `EverySixHours`
-    / `Daily` (default) / `Weekly`. Currently only the startup
-    check fires; the periodic timer that honors this setting is
-    a planned follow-up.
-  - **Include pre-release versions** — off by default. Now wired
+    / `Daily` (default) / `Weekly`.
+  - **Include pre-release versions** — off by default; wired
     through to the underlying GitHub release source.
-- `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.
+  - Dropdowns display friendly labels ("Every six hours" instead
+    of the raw `EverySixHours` enum identifier).
+- `settings.json` schema bumps v6 → v7 → v8. Both migrations are
+  no-ops: all new fields default to safe values, so pre-v6 files
+  load with the same effective behaviour they had before.
 
 ## [1.4.0] - 2026-05-29
 

DiffViewer.Tests/Services/SettingsServiceTests.cs

@@ -548,6 +548,46 @@ public void Save_Then_Load_RoundTripsAutoUpdateFields()
         svc2.Current.IncludePreReleases.Should().BeTrue();
     }
 
+    [Fact]
+    public void Load_V7File_MigratesToV8_SkippedUpdateVersionDefaultsToNull()
+    {
+        // v7 schema (current minus 1) had no skippedUpdateVersion
+        // field. After v7->v8 migration the field should hydrate to
+        // null (nothing skipped) and other fields should be
+        // preserved. Auto-update fields from v7 carry through
+        // unchanged.
+        var v7 = new JsonObject
+        {
+            ["schemaVersion"] = 7,
+            ["fontSize"] = 21,
+            ["autoUpdate"] = AutoUpdateMode.Automatic.ToString(),
+            ["updateCheckCadence"] = UpdateCheckCadence.Hourly.ToString(),
+            ["includePreReleases"] = true,
+        };
+        File.WriteAllText(_settingsPath, v7.ToJsonString());
+
+        var svc = new SettingsService(_settingsPath);
+
+        svc.LastLoadOutcome.Should().Be(SettingsLoadOutcome.Migrated);
+        svc.Current.FontSize.Should().Be(21);
+        svc.Current.AutoUpdate.Should().Be(AutoUpdateMode.Automatic);
+        svc.Current.UpdateCheckCadence.Should().Be(UpdateCheckCadence.Hourly);
+        svc.Current.IncludePreReleases.Should().BeTrue();
+        svc.Current.SkippedUpdateVersion.Should().BeNull();
+    }
+
+    [Fact]
+    public void Save_Then_Load_RoundTripsSkippedUpdateVersion()
+    {
+        var svc1 = new SettingsService(_settingsPath);
+        svc1.Save(svc1.Current with { SkippedUpdateVersion = "1.5.0-rc1" });
+
+        var svc2 = new SettingsService(_settingsPath);
+
+        svc2.LastLoadOutcome.Should().Be(SettingsLoadOutcome.Loaded);
+        svc2.Current.SkippedUpdateVersion.Should().Be("1.5.0-rc1");
+    }
+
     [Fact]
     public void RepoUrlMappings_StableOrderingOnDisk_AcrossSaves()
     {

DiffViewer.Tests/Utility/EnumDisplayConverterTests.cs

@@ -0,0 +1,67 @@
+using System.Globalization;
+using System.Windows.Data;
+using DiffViewer.Models;
+using DiffViewer.Utility;
+using FluentAssertions;
+using Xunit;
+
+namespace DiffViewer.Tests.Utility;
+
+public sealed class EnumDisplayConverterTests
+{
+    [Theory]
+    [InlineData(AutoUpdateMode.Automatic, "Automatic (silent install)")]
+    [InlineData(AutoUpdateMode.NotifyOnly, "Notify only (show banner)")]
+    [InlineData(AutoUpdateMode.Disabled, "Disabled")]
+    public void Convert_AutoUpdateMode_ProducesFriendlyString(AutoUpdateMode mode, string expected)
+    {
+        var result = EnumDisplayConverter.Instance.Convert(
+            mode, typeof(string), parameter: null, culture: CultureInfo.InvariantCulture);
+
+        result.Should().Be(expected);
+    }
+
+    [Theory]
+    [InlineData(UpdateCheckCadence.StartupOnly, "Startup only")]
+    [InlineData(UpdateCheckCadence.Hourly, "Hourly")]
+    [InlineData(UpdateCheckCadence.EverySixHours, "Every six hours")]
+    [InlineData(UpdateCheckCadence.Daily, "Daily")]
+    [InlineData(UpdateCheckCadence.Weekly, "Weekly")]
+    public void Convert_UpdateCheckCadence_ProducesFriendlyString(UpdateCheckCadence cadence, string expected)
+    {
+        var result = EnumDisplayConverter.Instance.Convert(
+            cadence, typeof(string), parameter: null, culture: CultureInfo.InvariantCulture);
+
+        result.Should().Be(expected);
+    }
+
+    [Fact]
+    public void Convert_UnknownValue_FallsBackToToString()
+    {
+        var result = EnumDisplayConverter.Instance.Convert(
+            "some-string", typeof(string), parameter: null, culture: CultureInfo.InvariantCulture);
+
+        result.Should().Be("some-string");
+    }
+
+    [Fact]
+    public void Convert_NullValue_ReturnsEmptyString()
+    {
+        var result = EnumDisplayConverter.Instance.Convert(
+            null, typeof(string), parameter: null, culture: CultureInfo.InvariantCulture);
+
+        result.Should().Be(string.Empty);
+    }
+
+    [Fact]
+    public void ConvertBack_ReturnsDoNothing()
+    {
+        // The converter only feeds the display path; the underlying
+        // enum value is what SelectedItem binds to. ConvertBack must
+        // not interfere.
+        var result = EnumDisplayConverter.Instance.ConvertBack(
+            "Daily", typeof(UpdateCheckCadence), parameter: null, culture: CultureInfo.InvariantCulture);
+
+        result.Should().Be(Binding.DoNothing);
+    }
+}

DiffViewer.Tests/Utility/UpdateCheckCadenceExtensionsTests.cs

@@ -0,0 +1,31 @@
+using System;
+using DiffViewer.Models;
+using DiffViewer.Utility;
+using FluentAssertions;
+using Xunit;
+
+namespace DiffViewer.Tests.Utility;
+
+public sealed class UpdateCheckCadenceExtensionsTests
+{
+    [Fact]
+    public void ToInterval_StartupOnly_IsNull()
+    {
+        UpdateCheckCadence.StartupOnly.ToInterval().Should().BeNull();
+    }
+
+    [Theory]
+    [InlineData(UpdateCheckCadence.Hourly, 1)]
+    [InlineData(UpdateCheckCadence.EverySixHours, 6)]
+    [InlineData(UpdateCheckCadence.Daily, 24)]
+    public void ToInterval_HourlyCadences_MapToHours(UpdateCheckCadence cadence, int expectedHours)
+    {
+        cadence.ToInterval().Should().Be(TimeSpan.FromHours(expectedHours));
+    }
+
+    [Fact]
+    public void ToInterval_Weekly_IsSevenDays()
+    {
+        UpdateCheckCadence.Weekly.ToInterval().Should().Be(TimeSpan.FromDays(7));
+    }
+}

DiffViewer.Tests/ViewModels/UpdateNotificationViewModelTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Threading;
 using System.Threading.Tasks;
@@ -15,7 +16,7 @@ public sealed class UpdateNotificationViewModelTests
     public async Task StartAsync_WhenDisabled_DoesNotCheck()
     {
         var fake = new FakeUpdateService();
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.Disabled);
+        var sut = NewVm(fake, () => AutoUpdateMode.Disabled);
 
         await sut.StartAsync(CancellationToken.None);
 
@@ -28,7 +29,7 @@ public async Task StartAsync_WhenAutomatic_ChecksDownloadsAndQueuesSilently_Then
     {
         var available = NewAvailable("1.5.0");
         var fake = new FakeUpdateService { CheckResult = available };
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.Automatic);
+        var sut = NewVm(fake, () => AutoUpdateMode.Automatic);
 
         await sut.StartAsync(CancellationToken.None);
 
@@ -45,7 +46,7 @@ public async Task StartAsync_WhenNotifyOnly_ChecksOnly_ThenShowsBannerWithInstal
     {
         var available = NewAvailable("2.0.0");
         var fake = new FakeUpdateService { CheckResult = available };
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.NotifyOnly);
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly);
 
         await sut.StartAsync(CancellationToken.None);
 
@@ -61,7 +62,7 @@ public async Task StartAsync_WhenNotifyOnly_ChecksOnly_ThenShowsBannerWithInstal
     public async Task StartAsync_WhenNoUpdateAvailable_LeavesBannerHidden()
     {
         var fake = new FakeUpdateService { CheckResult = UpdateCheckResult.NoUpdateAvailable };
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.NotifyOnly);
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly);
 
         await sut.StartAsync(CancellationToken.None);
 
@@ -71,12 +72,46 @@ public async Task StartAsync_WhenNoUpdateAvailable_LeavesBannerHidden()
         sut.ShowInstallButton.Should().BeFalse();
     }
 
+    [Fact]
+    public async Task StartAsync_WhenDetectedVersionMatchesSkipped_LeavesBannerHidden()
+    {
+        // A previously-skipped version should silently consume the
+        // detection: no banner, no download, no apply queue. The
+        // periodic re-check will still try again next interval (in
+        // case the user changes their mind).
+        var available = NewAvailable("1.5.0");
+        var fake = new FakeUpdateService { CheckResult = available };
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly, getSkipped: () => "1.5.0");
+
+        await sut.StartAsync(CancellationToken.None);
+
+        fake.CheckCalls.Should().Be(1);
+        fake.DownloadCalls.Should().BeEmpty();
+        sut.IsBannerVisible.Should().BeFalse();
+    }
+
+    [Fact]
+    public async Task StartAsync_WhenDetectedVersionDiffersFromSkipped_ShowsBanner()
+    {
+        // A previously-skipped older version should NOT suppress a
+        // newer detection — Skip is per-version, not "skip everything
+        // forever".
+        var available = NewAvailable("2.0.0");
+        var fake = new FakeUpdateService { CheckResult = available };
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly, getSkipped: () => "1.5.0");
+
+        await sut.StartAsync(CancellationToken.None);
+
+        sut.IsBannerVisible.Should().BeTrue();
+        sut.StatusText.Should().Contain("2.0.0");
+    }
+
     [Fact]
     public async Task Install_AfterNotifyOnlyCheck_DownloadsAndQueues_HidesInstallButton()
     {
         var available = NewAvailable("3.1.2");
         var fake = new FakeUpdateService { CheckResult = available };
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.NotifyOnly);
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly);
         await sut.StartAsync(CancellationToken.None);
 
         await sut.InstallCommand.ExecuteAsync(null);
@@ -96,7 +131,7 @@ public async Task Install_WithNoPendingUpdate_NoOps()
         // command. The VM should defend against the missing _pending
         // by doing nothing rather than dereferencing null.
         var fake = new FakeUpdateService();
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.NotifyOnly);
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly);
 
         await sut.InstallCommand.ExecuteAsync(null);
 
@@ -107,13 +142,9 @@ public async Task Install_WithNoPendingUpdate_NoOps()
     [Fact]
     public async Task Dismiss_HidesBanner_DoesNotCancelQueuedApply()
     {
-        // The "Dismiss" UX is session-scoped — it hides the banner but
-        // doesn't roll back the queued ApplyOnNextLaunch from the
-        // Automatic-mode flow. The update still installs on next exit;
-        // the user just doesn't keep seeing the notification.
         var available = NewAvailable("1.0.0");
         var fake = new FakeUpdateService { CheckResult = available };
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => AutoUpdateMode.Automatic);
+        var sut = NewVm(fake, () => AutoUpdateMode.Automatic);
         await sut.StartAsync(CancellationToken.None);
         sut.IsBannerVisible.Should().BeTrue();
 
@@ -123,6 +154,34 @@ public async Task Dismiss_HidesBanner_DoesNotCancelQueuedApply()
         fake.ApplyOnNextLaunchCalls.Should().HaveCount(1); // unchanged
     }
 
+    [Fact]
+    public async Task Skip_HidesBanner_AndPersistsSkippedVersion()
+    {
+        var available = NewAvailable("1.5.0");
+        var fake = new FakeUpdateService { CheckResult = available };
+        var setCalls = new List<string?>();
+        var sut = NewVm(fake, () => AutoUpdateMode.NotifyOnly, setSkipped: v => setCalls.Add(v));
+        await sut.StartAsync(CancellationToken.None);
+        sut.IsBannerVisible.Should().BeTrue();
+
+        sut.SkipCommand.Execute(null);
+
+        sut.IsBannerVisible.Should().BeFalse();
+        setCalls.Should().ContainSingle().Which.Should().Be("1.5.0");
+    }
+
+    [Fact]
+    public void Skip_WithNoPendingUpdate_NoOps()
+    {
+        var setCalls = new List<string?>();
+        var sut = NewVm(new FakeUpdateService(), () => AutoUpdateMode.NotifyOnly,
+            setSkipped: v => setCalls.Add(v));
+
+        sut.SkipCommand.Execute(null);
+
+        setCalls.Should().BeEmpty();
+    }
+
     [Fact]
     public async Task GetMode_ReadAtEachStart_AllowsLiveModeChanges()
     {
@@ -133,7 +192,7 @@ public async Task GetMode_ReadAtEachStart_AllowsLiveModeChanges()
         // future refactor from accidentally capturing a snapshot).
         var mode = AutoUpdateMode.Disabled;
         var fake = new FakeUpdateService { CheckResult = NewAvailable("9.9.9") };
-        var sut = new UpdateNotificationViewModel(fake, getMode: () => mode);
+        var sut = NewVm(fake, () => mode);
 
         await sut.StartAsync(CancellationToken.None);
         fake.CheckCalls.Should().Be(0);
@@ -143,6 +202,22 @@ public async Task GetMode_ReadAtEachStart_AllowsLiveModeChanges()
         fake.CheckCalls.Should().Be(1);
     }
 
+    private static UpdateNotificationViewModel NewVm(
+        IUpdateService updates,
+        Func<AutoUpdateMode> getMode,
+        Func<UpdateCheckCadence>? getCadence = null,
+        Func<string?>? getSkipped = null,
+        Action<string?>? setSkipped = null)
+    {
+        return new UpdateNotificationViewModel(
+            updates,
+            getMode,
+            getCadence ?? (() => UpdateCheckCadence.Daily),
+            getSkipped ?? (() => null),
+            setSkipped ?? (_ => { }),
+            useDispatcherTimer: false);
+    }
+
     private static UpdateCheckResult NewAvailable(string version) =>
         new() { IsAvailable = true, Version = version, OpaqueHandle = new object() };
 

DiffViewer/App.xaml.cs

@@ -172,7 +172,10 @@ protected override async void OnStartup(StartupEventArgs e)
                 ?? (IUpdateService)new NullUpdateService();
         _updateNotification = new UpdateNotificationViewModel(
             updateService,
-            getMode: () => settingsService.Current.AutoUpdate);
+            getMode: () => settingsService.Current.AutoUpdate,
+            getCadence: () => settingsService.Current.UpdateCheckCadence,
+            getSkippedVersion: () => settingsService.Current.SkippedUpdateVersion,
+            setSkippedVersion: version => settingsService.Update(s => s with { SkippedUpdateVersion = version }));
         window.AttachUpdateNotification(_updateNotification);
 
         window.Closed += async (_, _) =>
@@ -206,6 +209,7 @@ protected override void OnExit(ExitEventArgs e)
         try { _shutdownCts?.Cancel(); } catch { }
         try { _shutdownCts?.Dispose(); } catch { }
         try { _httpClient?.Dispose(); } catch { }
+        try { _updateNotification?.Dispose(); } catch { }
         base.OnExit(e);
     }
 }