Serve 503 when PocketBase is unavailable across all content pages

Elternbeirat.Web/Features/Embeds/EventsEmbed.razor

@@ -1,12 +1,7 @@
-<section class="embed embed-events">
-    <h2>Kommende Termine</h2>
-
-    @if (_upcoming.Count == 0)
-    {
-        <p>Zurzeit sind keine Termine geplant.</p>
-    }
-    else
-    {
+@if (_upcoming.Count > 0)
+{
+    <section class="embed embed-events">
+        <h2>Kommende Termine</h2>
         <ul class="event-list">
             @foreach (var ev in _upcoming)
             {
@@ -21,5 +16,5 @@
             }
         </ul>
         <p class="embed-more"><a href="/events">Alle Termine <span aria-hidden="true">&rarr;</span></a></p>
-    }
-</section>
+    </section>
+}

Elternbeirat.Web/Features/Embeds/EventsEmbed.razor.cs

@@ -6,14 +6,24 @@ namespace Elternbeirat.Web.Features.Embeds;
 
 public partial class EventsEmbed
 {
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load events for an embed from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
+    // Number of upcoming events shown in the teaser; the full list is one link away.
+    private const int TeaserCount = 3;
+
+    [LoggerMessage(
+        Level = LogLevel.Warning,
+        Message = "Could not load events for an embed from PocketBase; the teaser is omitted.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<EventsEmbed> Logger { get; set; } = default!;
+    private ILogger<EventsEmbed> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<Event> _upcoming = [];
 
@@ -22,22 +32,25 @@ public partial class EventsEmbed
         IReadOnlyList<Event> events;
         try
         {
-            events = await PocketBase.GetEventsAsync();
+            events = await PocketBase.GetEventsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show no teaser instead of a 500.
-            LogLoadFailed(Logger, ex);
+            // Only part of the page fails: omit the teaser, keep the page (and its
+            // 200) intact. A missing teaser is degraded, not broken.
+            LogSourceUnavailable(Logger, exception);
             return;
         }
 
-        // Teaser: the three soonest upcoming events, earliest first. An event
-        // earlier today still counts as upcoming.
+        // Teaser: the soonest upcoming events, earliest first. An event earlier
+        // today still counts as upcoming.
         var today = DateOnly.FromDateTime(DateTime.Today);
-        _upcoming = events
-            .Where(e => DateOnly.FromDateTime(e.Start) >= today)
-            .OrderBy(e => e.Start)
-            .Take(3)
-            .ToList();
+        _upcoming =
+        [
+            .. events
+                .Where(@event => DateOnly.FromDateTime(@event.Start) >= today)
+                .OrderBy(@event => @event.Start)
+                .Take(TeaserCount)
+        ];
     }
 }

Elternbeirat.Web/Features/Embeds/FaqsEmbed.razor

@@ -1,12 +1,7 @@
-<section class="embed embed-faqs">
-    <h2>Häufige Fragen</h2>
-
-    @if (_faqs.Count == 0)
-    {
-        <p>Zurzeit gibt es keine Fragen.</p>
-    }
-    else
-    {
+@if (_faqs.Count > 0)
+{
+    <section class="embed embed-faqs">
+        <h2>Häufige Fragen</h2>
         @foreach (var faq in _faqs)
         {
             <details class="faq-item">
@@ -17,5 +12,5 @@
             </details>
         }
         <p class="embed-more"><a href="/faqs">Alle Fragen <span aria-hidden="true">&rarr;</span></a></p>
-    }
-</section>
+    </section>
+}

Elternbeirat.Web/Features/Embeds/FaqsEmbed.razor.cs

@@ -6,14 +6,24 @@ namespace Elternbeirat.Web.Features.Embeds;
 
 public partial class FaqsEmbed
 {
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load FAQs for an embed from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
+    // Number of questions shown in the teaser; the full hub is one link away.
+    private const int TeaserCount = 3;
+
+    [LoggerMessage(
+        Level = LogLevel.Warning,
+        Message = "Could not load FAQs for an embed from PocketBase; the teaser is omitted.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<FaqsEmbed> Logger { get; set; } = default!;
+    private ILogger<FaqsEmbed> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<Faq> _faqs = [];
 
@@ -21,14 +31,16 @@ public partial class FaqsEmbed
     {
         try
         {
-            // Teaser: the first three questions, with a link to the full hub.
-            var faqs = await PocketBase.GetFaqsAsync();
-            _faqs = [.. faqs.Take(3)];
+            // GetFaqsAsync is ordered by topic, then question, so the first entries
+            // the teaser takes are stable across requests.
+            var faqs = await PocketBase.GetFaqsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
+            _faqs = [.. faqs.Take(TeaserCount)];
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show no teaser instead of a 500.
-            LogLoadFailed(Logger, ex);
+            // Only part of the page fails: omit the teaser, keep the page (and its
+            // 200) intact. A missing teaser is degraded, not broken.
+            LogSourceUnavailable(Logger, exception);
         }
     }
 }

Elternbeirat.Web/Features/Embeds/PostsEmbed.razor

@@ -1,23 +1,18 @@
-<section class="embed embed-posts">
-    <h2>Aktuelle Beiträge</h2>
-
-    @if (_latest.Count == 0)
-    {
-        <p>Zurzeit gibt es keine Beiträge.</p>
-    }
-    else
-    {
+@if (_latest.Count > 0)
+{
+    <section class="embed embed-posts">
+        <h2>Aktuelle Beiträge</h2>
         <ul class="post-list">
             @foreach (var post in _latest)
             {
                 <li>
                     <a href="@($"/posts/{post.Slug}")">@post.Title</a>
-                    <time datetime="@post.Date.ToString("yyyy-MM-dd")">
-                        @post.Date.ToString("d. MMMM yyyy", German)
+                    <time datetime="@post.Date.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture)">
+                        @post.Date.ToString("d. MMMM yyyy", Cultures.German)
                     </time>
                 </li>
             }
         </ul>
         <p class="embed-more"><a href="/posts">Alle Beiträge <span aria-hidden="true">&rarr;</span></a></p>
-    }
-</section>
+    </section>
+}

Elternbeirat.Web/Features/Embeds/PostsEmbed.razor.cs

@@ -1,4 +1,3 @@
-using System.Globalization;
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
 using Microsoft.AspNetCore.Components;
@@ -7,16 +6,24 @@ namespace Elternbeirat.Web.Features.Embeds;
 
 public partial class PostsEmbed
 {
-    private static readonly CultureInfo German = CultureInfo.GetCultureInfo("de-DE");
+    // Number of posts shown in the teaser; the full list is one link away.
+    private const int TeaserCount = 3;
 
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load posts for an embed from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
+    [LoggerMessage(
+        Level = LogLevel.Warning,
+        Message = "Could not load posts for an embed from PocketBase; the teaser is omitted.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<PostsEmbed> Logger { get; set; } = default!;
+    private ILogger<PostsEmbed> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<Post> _latest = [];
 
@@ -24,14 +31,15 @@ public partial class PostsEmbed
     {
         try
         {
-            // Teaser: the three most recent posts, with a link to the full list.
-            var posts = await PocketBase.GetPostsAsync();
-            _latest = [.. posts.Take(3)];
+            // GetPostsAsync returns newest first, so the first entries are the latest.
+            var posts = await PocketBase.GetPostsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
+            _latest = [.. posts.Take(TeaserCount)];
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show no teaser instead of a 500.
-            LogLoadFailed(Logger, ex);
+            // Only part of the page fails: omit the teaser, keep the page (and its
+            // 200) intact. A missing teaser is degraded, not broken.
+            LogSourceUnavailable(Logger, exception);
         }
     }
 }

Elternbeirat.Web/Features/Events/EventList.razor

@@ -4,53 +4,60 @@
 
 <h1>Termine</h1>
 
-<p class="intro">
-    Alle Termine des Elternbeirats auf einen Blick. Sie können den Kalender auch
-    <a href="/events.ics">abonnieren</a> und in Ihrer Kalender-App automatisch
-    aktuell halten.
-</p>
-
-<h2>Kommende Termine</h2>
-
-@if (_upcoming.Count == 0)
+@if (_unavailable)
 {
-    <p>Zurzeit sind keine Termine geplant.</p>
+    <p>Die Termine sind gerade nicht erreichbar. Bitte später erneut versuchen.</p>
 }
 else
 {
-    <ul class="event-list">
-        @foreach (var ev in _upcoming)
-        {
-            <li>
-                <time datetime="@ev.Start.ToString("s")">@EventFormat.Range(ev)</time>
-                <span class="event-title">@ev.Title</span>
-                @if (!string.IsNullOrWhiteSpace(ev.Location))
-                {
-                    <span class="event-location">@ev.Location</span>
-                }
-                @if (!string.IsNullOrWhiteSpace(ev.Note))
-                {
-                    <p class="event-note">@ev.Note</p>
-                }
-            </li>
-        }
-    </ul>
-}
+    <p class="intro">
+        Alle Termine des Elternbeirats auf einen Blick. Sie können den Kalender auch
+        <a href="/events.ics">abonnieren</a> und in Ihrer Kalender-App automatisch
+        aktuell halten.
+    </p>
 
-@if (_past.Count > 0)
-{
-    <h2>Vergangene Termine</h2>
-    <ul class="event-list event-list-past">
-        @foreach (var ev in _past)
-        {
-            <li>
-                <time datetime="@ev.Start.ToString("s")">@EventFormat.Range(ev)</time>
-                <span class="event-title">@ev.Title</span>
-                @if (!string.IsNullOrWhiteSpace(ev.Location))
-                {
-                    <span class="event-location">@ev.Location</span>
-                }
-            </li>
-        }
-    </ul>
+    <h2>Kommende Termine</h2>
+
+    @if (_upcoming.Count == 0)
+    {
+        <p>Zurzeit sind keine Termine geplant.</p>
+    }
+    else
+    {
+        <ul class="event-list">
+            @foreach (var ev in _upcoming)
+            {
+                <li>
+                    <time datetime="@ev.Start.ToString("s")">@EventFormat.Range(ev)</time>
+                    <span class="event-title">@ev.Title</span>
+                    @if (!string.IsNullOrWhiteSpace(ev.Location))
+                    {
+                        <span class="event-location">@ev.Location</span>
+                    }
+                    @if (!string.IsNullOrWhiteSpace(ev.Note))
+                    {
+                        <p class="event-note">@ev.Note</p>
+                    }
+                </li>
+            }
+        </ul>
+    }
+
+    @if (_past.Count > 0)
+    {
+        <h2>Vergangene Termine</h2>
+        <ul class="event-list event-list-past">
+            @foreach (var ev in _past)
+            {
+                <li>
+                    <time datetime="@ev.Start.ToString("s")">@EventFormat.Range(ev)</time>
+                    <span class="event-title">@ev.Title</span>
+                    @if (!string.IsNullOrWhiteSpace(ev.Location))
+                    {
+                        <span class="event-location">@ev.Location</span>
+                    }
+                </li>
+            }
+        </ul>
+    }
 }

Elternbeirat.Web/Features/Events/EventList.razor.cs

@@ -1,48 +1,67 @@
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
+using Elternbeirat.Web.Shared;
 using Microsoft.AspNetCore.Components;
 
 namespace Elternbeirat.Web.Features.Events;
 
 public partial class EventList
 {
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load events from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
+    [LoggerMessage(
+        Level = LogLevel.Error,
+        Message = "Could not load events from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<EventList> Logger { get; set; } = default!;
+    private ILogger<EventList> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<Event> _upcoming = [];
     private IReadOnlyList<Event> _past = [];
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of "no events", matching the
+    // 503 this sets on the response.
+    private bool _unavailable;
+
     protected override async Task OnInitializedAsync()
     {
         IReadOnlyList<Event> events;
         try
         {
-            events = await PocketBase.GetEventsAsync();
+            events = await PocketBase.GetEventsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show empty sections instead of a 500. The page
-            // stays up; the "keine Termine" note is rendered.
-            LogLoadFailed(Logger, ex);
+            // Empty sections would claim there are no events. The site works, its
+            // data store is down: 503 and an honest note.
+            LogSourceUnavailable(Logger, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
             return;
         }
 
         // Split into upcoming and past by date, so an event earlier today still
         // counts as upcoming. Upcoming earliest first, past most recent first.
         var today = DateOnly.FromDateTime(DateTime.Today);
-        _upcoming = events
-            .Where(e => DateOnly.FromDateTime(e.Start) >= today)
-            .OrderBy(e => e.Start)
-            .ToList();
-        _past = events
-            .Where(e => DateOnly.FromDateTime(e.Start) < today)
-            .OrderByDescending(e => e.Start)
-            .ToList();
+        _upcoming =
+        [
+            .. events
+                .Where(@event => DateOnly.FromDateTime(@event.Start) >= today)
+                .OrderBy(@event => @event.Start)
+        ];
+        _past =
+        [
+            .. events
+                .Where(@event => DateOnly.FromDateTime(@event.Start) < today)
+                .OrderByDescending(@event => @event.Start)
+        ];
     }
 }

Elternbeirat.Web/Features/Faqs/FaqList.razor

@@ -4,7 +4,11 @@
 
 <h1>Häufige Fragen</h1>
 
-@if (_groups.Count == 0)
+@if (_unavailable)
+{
+    <p>Die Fragen sind gerade nicht erreichbar. Bitte später erneut versuchen.</p>
+}
+else if (_groups.Count == 0)
 {
     <p>Zurzeit gibt es keine Fragen.</p>
 }

Elternbeirat.Web/Features/Faqs/FaqList.razor.cs

@@ -1,13 +1,18 @@
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
+using Elternbeirat.Web.Shared;
 using Microsoft.AspNetCore.Components;
 
 namespace Elternbeirat.Web.Features.Faqs;
 
 public partial class FaqList
 {
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load FAQs from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
+    [LoggerMessage(
+        Level = LogLevel.Error,
+        Message = "Could not load FAQs from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     // German heading per topic. Unknown topics fall back to the raw key so a new
     // topic in PocketBase still shows up rather than being silently dropped.
@@ -21,28 +26,38 @@ public partial class FaqList
         };
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<FaqList> Logger { get; set; } = default!;
+    private ILogger<FaqList> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<IGrouping<string, Faq>> _groups = [];
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of "no questions", matching
+    // the 503 this sets on the response.
+    private bool _unavailable;
+
     protected override async Task OnInitializedAsync()
     {
         try
         {
-            var faqs = await PocketBase.GetFaqsAsync();
+            var faqs = await PocketBase.GetFaqsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
             _groups = [.. faqs.GroupBy(faq => faq.Topic)];
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show an empty page instead of a 500. The page
-            // stays up; the "keine Fragen" note is rendered.
-            LogLoadFailed(Logger, ex);
+            // An empty page would claim there are no questions. The site works, its
+            // data store is down: 503 and an honest note.
+            LogSourceUnavailable(Logger, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
         }
     }
 
-    private static string TopicLabel(string topic) =>
-        TopicLabels.TryGetValue(topic, out var label) ? label : topic;
+    private static string TopicLabel(string topic)
+        => TopicLabels.GetValueOrDefault(topic, topic);
 }

Elternbeirat.Web/Features/Home/Home.razor.cs

@@ -8,8 +8,8 @@ public partial class Home
 {
     [LoggerMessage(
         Level = LogLevel.Warning,
-        Message = "Could not load the home page from PocketBase.")]
-    private static partial void LogLoadFailed(
+        Message = "Could not load the home page from PocketBase; embeds are omitted.")]
+    private static partial void LogSourceUnavailable(
         ILogger logger,
         Exception exception);
 
@@ -19,6 +19,9 @@ public partial class Home
     [Inject]
     private ILogger<Home> Logger { get; set; } = null!;
 
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
+
     // Which dynamic blocks the home page shows is editorial: it comes from the
     // "home" page's embed field in PocketBase, not from hard-coded markup.
     private IReadOnlyList<string> _embed = [];
@@ -27,14 +30,15 @@ public partial class Home
     {
         try
         {
-            var pages = await PocketBase.GetPagesAsync();
+            var pages = await PocketBase.GetPagesAsync(HttpContext?.RequestAborted ?? default);
             var home = pages.FirstOrDefault(page => Page.IsHomeSlug(page.Slug));
             _embed = home?.Embed ?? [];
         }
-        catch (HttpRequestException exception)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> render the intro without embeds instead of a 500.
-            LogLoadFailed(Logger, exception);
+            // Only the embeds fail: render the static intro without them instead of a
+            // 500. The home page's own text is markup, so it stays intact.
+            LogSourceUnavailable(Logger, exception);
         }
     }
 }

Elternbeirat.Web/Features/Pages/ContentPage.razor

@@ -1,14 +1,18 @@
 @page "/{Slug}"
 
-@if (_page is null)
+@if (_unavailable)
 {
-    <PageTitle>Nicht gefunden</PageTitle>
+    <PageTitle>Vorübergehend nicht erreichbar</PageTitle>
+    <p>Die Seite ist gerade nicht erreichbar. Bitte später erneut versuchen.</p>
 }
-else
+else if (_page is not null)
 {
     <PageTitle>@_page.Title</PageTitle>
     <article>
+        <h1>@_page.Title</h1>
         @Body
     </article>
     <PageEmbeds Embed="_page.Embed" />
 }
+@* No page and not unavailable: the slug was unknown; NavigationManager.NotFound()
+   already ran in OnParametersSetAsync and renders the not-found page. *@

Elternbeirat.Web/Features/Pages/ContentPage.razor.cs

@@ -8,9 +8,9 @@ namespace Elternbeirat.Web.Features.Pages;
 public partial class ContentPage
 {
     [LoggerMessage(
-        Level = LogLevel.Warning,
-        Message = "Could not load page '{slug}' from PocketBase.")]
-    private static partial void LogLoadFailed(
+        Level = LogLevel.Error,
+        Message = "Could not load page '{Slug}' from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
         ILogger logger,
         string slug,
         Exception exception);
@@ -24,11 +24,19 @@ public partial class ContentPage
     [Inject]
     private ILogger<ContentPage> Logger { get; set; } = null!;
 
+    [Inject]
+    private NavigationManager Navigation { get; set; } = null!;
+
     [CascadingParameter]
     private HttpContext? HttpContext { get; set; }
 
     private Page? _page;
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of a not-found page, matching
+    // the 503 this sets on the response.
+    private bool _unavailable;
+
     // The page body rendered from Markdown to HTML, ready to emit as a
     // MarkupString in the markup.
     private MarkupString Body => (MarkupString)Markdown.ToHtml(_page?.Body);
@@ -37,24 +45,23 @@ public partial class ContentPage
     {
         try
         {
-            var pages = await PocketBase.GetPagesAsync();
+            var pages = await PocketBase.GetPagesAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
             _page = pages.FirstOrDefault(
-                p => string.Equals(p.Slug, Slug, StringComparison.OrdinalIgnoreCase));
+                page => string.Equals(page.Slug, Slug, StringComparison.OrdinalIgnoreCase));
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> treat as "not found" rather than a 500. The
-            // 404 branch below serves the friendly /not-found page.
-            LogLoadFailed(Logger, Slug, ex);
-            _page = null;
+            // The site works, its data store is down: 503, not 404.
+            LogSourceUnavailable(Logger, Slug, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
+            return;
         }
 
-        // Unknown slug (or unreachable source) -> 404, so
-        // UseStatusCodePagesWithReExecute serves the /not-found page instead of an
-        // empty 200 response.
-        if (_page is null && HttpContext is not null)
+        if (_page is null)
         {
-            HttpContext.Response.StatusCode = StatusCodes.Status404NotFound;
+            // The source answered, but there is no page with this slug: a genuine 404.
+            Navigation.NotFound();
         }
     }
 }

Elternbeirat.Web/Features/Posts/PostDetail.razor

@@ -1,19 +1,25 @@
 @page "/posts/{Slug}"
 
-@if (_post is null)
+@if (_unavailable)
 {
-    <PageTitle>Nicht gefunden</PageTitle>
+    <PageTitle>Vorübergehend nicht erreichbar</PageTitle>
+    <p>Der Beitrag ist gerade nicht erreichbar. Bitte später erneut versuchen.</p>
 }
-else
+else if (_post is not null)
 {
     <PageTitle>@_post.Title</PageTitle>
+    <nav>
+        <a href="/posts">&larr; Alle Beiträge</a>
+    </nav>
     <article>
-        <p class="post-meta">
-            <a href="/posts">&larr; Alle Beiträge</a>
-            <time datetime="@_post.Date.ToString("yyyy-MM-dd")">
-                @_post.Date.ToString("d. MMMM yyyy", German)
+        <header>
+            <h1>@_post.Title</h1>
+            <time class="post-meta" datetime="@_post.Date.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture)">
+                @_post.Date.ToString("d. MMMM yyyy", Cultures.German)
             </time>
-        </p>
+        </header>
         @Body
     </article>
 }
+@* No post and not unavailable: the slug was unknown; NavigationManager.NotFound()
+   already ran in OnParametersSetAsync and renders the not-found page. *@

Elternbeirat.Web/Features/Posts/PostDetail.razor.cs

@@ -1,33 +1,42 @@
-using System.Globalization;
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
 using Elternbeirat.Web.Shared;
 using Microsoft.AspNetCore.Components;
-using Microsoft.AspNetCore.Http;
 
 namespace Elternbeirat.Web.Features.Posts;
 
 public partial class PostDetail
 {
-    private static readonly CultureInfo German = CultureInfo.GetCultureInfo("de-DE");
-
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load post '{slug}' from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, string slug, Exception exception);
+    [LoggerMessage(
+        Level = LogLevel.Error,
+        Message = "Could not load post '{Slug}' from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        string slug,
+        Exception exception);
 
     [Parameter]
     public string Slug { get; set; } = string.Empty;
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<PostDetail> Logger { get; set; } = default!;
+    private ILogger<PostDetail> Logger { get; set; } = null!;
+
+    [Inject]
+    private NavigationManager Navigation { get; set; } = null!;
 
     [CascadingParameter]
     private HttpContext? HttpContext { get; set; }
 
     private Post? _post;
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of a not-found page, matching
+    // the 503 this sets on the response.
+    private bool _unavailable;
+
     // The post body rendered from Markdown to HTML, ready to emit as a
     // MarkupString in the markup.
     private MarkupString Body => (MarkupString)Markdown.ToHtml(_post?.Body);
@@ -36,24 +45,23 @@ public partial class PostDetail
     {
         try
         {
-            var posts = await PocketBase.GetPostsAsync();
+            var posts = await PocketBase.GetPostsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
             _post = posts.FirstOrDefault(
-                p => string.Equals(p.Slug, Slug, StringComparison.OrdinalIgnoreCase));
+                post => string.Equals(post.Slug, Slug, StringComparison.OrdinalIgnoreCase));
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> treat as "not found" rather than a 500. The
-            // 404 branch below serves the friendly /not-found page.
-            LogLoadFailed(Logger, Slug, ex);
-            _post = null;
+            // The site works, its data store is down: 503, not 404.
+            LogSourceUnavailable(Logger, Slug, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
+            return;
         }
 
-        // Unknown slug (or unreachable source) -> 404, so
-        // UseStatusCodePagesWithReExecute serves the /not-found page instead of an
-        // empty 200 response.
-        if (_post is null && HttpContext is not null)
+        if (_post is null)
         {
-            HttpContext.Response.StatusCode = StatusCodes.Status404NotFound;
+            // The source answered, but there is no post with this slug: a genuine 404.
+            Navigation.NotFound();
         }
     }
 }

Elternbeirat.Web/Features/Posts/PostList.razor

@@ -4,7 +4,11 @@
 
 <h1>Beiträge</h1>
 
-@if (_posts.Count == 0)
+@if (_unavailable)
+{
+    <p>Die Beiträge sind gerade nicht erreichbar. Bitte später erneut versuchen.</p>
+}
+else if (_posts.Count == 0)
 {
     <p>Zurzeit gibt es keine Beiträge.</p>
 }
@@ -15,8 +19,8 @@ else
         {
             <li>
                 <a href="@($"/posts/{post.Slug}")">@post.Title</a>
-                <time datetime="@post.Date.ToString("yyyy-MM-dd")">
-                    @post.Date.ToString("d. MMMM yyyy", German)
+                <time datetime="@post.Date.ToString("yyyy-MM-dd", CultureInfo.InvariantCulture)">
+                    @post.Date.ToString("d. MMMM yyyy", Cultures.German)
                 </time>
             </li>
         }

Elternbeirat.Web/Features/Posts/PostList.razor.cs

@@ -1,36 +1,48 @@
-using System.Globalization;
 using Elternbeirat.Contracts;
 using Elternbeirat.PocketBase;
+using Elternbeirat.Web.Shared;
 using Microsoft.AspNetCore.Components;
 
 namespace Elternbeirat.Web.Features.Posts;
 
 public partial class PostList
 {
-    [LoggerMessage(Level = LogLevel.Warning, Message = "Could not load posts from PocketBase.")]
-    private static partial void LogLoadFailed(ILogger logger, Exception exception);
-
-    private static readonly CultureInfo German = CultureInfo.GetCultureInfo("de-DE");
+    [LoggerMessage(
+        Level = LogLevel.Error,
+        Message = "Could not load posts from PocketBase; content source is unavailable.")]
+    private static partial void LogSourceUnavailable(
+        ILogger logger,
+        Exception exception);
 
     [Inject]
-    private PocketBaseClient PocketBase { get; set; } = default!;
+    private PocketBaseClient PocketBase { get; set; } = null!;
 
     [Inject]
-    private ILogger<PostList> Logger { get; set; } = default!;
+    private ILogger<PostList> Logger { get; set; } = null!;
+
+    [CascadingParameter]
+    private HttpContext? HttpContext { get; set; }
 
     private IReadOnlyList<Post> _posts = [];
 
+    // Set when the content source could not be reached or read. The markup then
+    // shows a "temporarily unavailable" note instead of "no posts", matching the
+    // 503 this sets on the response.
+    private bool _unavailable;
+
     protected override async Task OnInitializedAsync()
     {
         try
         {
-            _posts = await PocketBase.GetPostsAsync();
+            _posts = await PocketBase.GetPostsAsync(HttpContext?.RequestAborted ?? CancellationToken.None);
         }
-        catch (HttpRequestException ex)
+        catch (PocketBaseUnavailableException exception)
         {
-            // Source unreachable -> show an empty list instead of a 500. The page
-            // stays up; the "keine Beiträge" note is rendered.
-            LogLoadFailed(Logger, ex);
+            // An empty list would claim there are no posts. The site works, its
+            // data store is down: 503 and an honest note.
+            LogSourceUnavailable(Logger, exception);
+            _unavailable = true;
+            SourceUnavailable.SetStatus(HttpContext);
         }
     }
 }