Read a post's date as the Berlin calendar day, not the raw UTC day

Elternbeirat.Contracts/Post.cs

@@ -1,3 +1,4 @@
+using System.ComponentModel;
 using System.Text.Json.Serialization;
 
 namespace Elternbeirat.Contracts;
@@ -17,14 +18,16 @@ public record Post
     public string Id { get; init; } = "";
 
     /// <summary>
-    ///     Gets the publication date as Europe/Berlin wall-clock time.
+    ///     Gets the publication date as a calendar day.
     /// </summary>
     /// <remarks>
-    ///     PocketBase stores the value in UTC; it is converted to Berlin local time on
-    ///     deserialization, with daylight saving applied. Only the date part is shown.
+    ///     A post's date is a plain day, not a point in time. It is read as the
+    ///     Berlin calendar day: the UTC value is converted to Europe/Berlin and only
+    ///     the day is kept, so the day an editor picked is the day shown -- no
+    ///     time-of-day, no off-by-one at midnight. See <see cref="DateOnlyConverter"/>.
     /// </remarks>
     [JsonPropertyName("date")]
-    public DateTime Date { get; init; }
+    public DateOnly Date { get; init; }
 
     /// <summary>
     ///     Gets the heading shown to visitors.

Elternbeirat.PocketBase/DateOnlyConverter.cs

@@ -0,0 +1,44 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace Elternbeirat.PocketBase;
+
+/// <summary>
+///     JSON converter that reads and writes a PocketBase date as a calendar date
+///     (<see cref="DateOnly"/>), ignoring the time-of-day and the time zone.
+/// </summary>
+/// <remarks>
+///     PocketBase has no date-only field type: it stores every date as a UTC
+///     instant with a time-of-day (e.g. an editor's <c>2 Jan 00:00</c> Berlin is
+///     stored as <c>"2026-01-01 22:00:00.000Z"</c>). The day the editor meant is
+///     therefore the day <em>in Berlin</em>, not the day of the raw UTC string. This
+///     converter reuses the same UTC-&gt;Berlin conversion as
+///     <see cref="LocalDateTimeConverter"/> and then keeps only the date, so the day
+///     shown is the day that was entered -- with no time-of-day and no off-by-one.
+/// </remarks>
+/// <remarks>
+///     Registered on the client's <see cref="System.Text.Json.JsonSerializerOptions"/>
+///     and matched by the <see cref="DateOnly"/> field type, so a contract needs no
+///     per-field attribute (which would couple the contract to this project).
+/// </remarks>
+public sealed class DateOnlyConverter : JsonConverter<DateOnly>
+{
+    /// <inheritdoc/>
+    /// <exception cref="FormatException">
+    ///     The stored value is not a valid date string.
+    /// </exception>
+    public override DateOnly Read(
+        ref Utf8JsonReader reader,
+        Type typeToConvert,
+        JsonSerializerOptions options)
+        => WallClock.Parse(reader.GetString()) is { } berlin
+            ? DateOnly.FromDateTime(berlin)
+            : default;
+
+    /// <inheritdoc/>
+    public override void Write(
+        Utf8JsonWriter writer,
+        DateOnly value,
+        JsonSerializerOptions options)
+        => writer.WriteStringValue(WallClock.Format(value.ToDateTime(TimeOnly.MinValue)));
+}

Elternbeirat.PocketBase/PocketBaseClient.cs

@@ -83,7 +83,8 @@ public sealed class PocketBaseClient(HttpClient http)
         => GetRecordsAsync<Faq>("faqs", "topic", ct);
 
     /// <summary>
-    ///     Creates the serializer options with both wall-clock date converters registered.
+    ///     Creates the serializer options with the date converters registered: the
+    ///     wall-clock ones for points in time and the calendar-day one for plain dates.
     /// </summary>
     /// <returns>
     ///     The configured options.
@@ -96,6 +97,7 @@ public sealed class PocketBaseClient(HttpClient http)
         };
         options.Converters.Add(new LocalDateTimeConverter());
         options.Converters.Add(new NullableLocalDateTimeConverter());
+        options.Converters.Add(new DateOnlyConverter());
         return options;
     }
 

Elternbeirat.Web.Tests/PocketBaseClientTests.cs

@@ -64,6 +64,20 @@ public sealed class PocketBaseClientTests(PocketBaseFixture pocketBase)
         posts.Select(p => p.Title).ShouldBe(["Neuer Vorstand", "Neue Sporthalle"]);
     }
 
+    [Fact]
+    public async Task Post_date_is_the_berlin_calendar_day()
+    {
+        var client = pocketBase.CreateClient();
+
+        var posts = await client.GetPostsAsync();
+
+        // The post is seeded as 2026-03-01 23:30Z, which is 2 March 00:30 in Berlin.
+        // The date is the Berlin day the editor picked (2 March), not the raw UTC
+        // day (1 March) -- the time zone is applied before the day is taken.
+        var post = posts.Single(p => p.Title == "Neuer Vorstand");
+        post.Date.ShouldBe(new DateOnly(2026, 3, 2));
+    }
+
     [Fact]
     public async Task Pages_exclude_non_public_records()
     {

Elternbeirat.Web.Tests/PocketBaseFixture.cs

@@ -283,10 +283,13 @@ public sealed class PocketBaseFixture : IAsyncLifetime
             order = 9, slug = "draft", embed = Array.Empty<string>(), @public = false,
         });
 
-        // Posts: newest first once sorted by -date.
+        // Posts: newest first once sorted by -date. The first post is stored as
+        // 2026-03-01 23:30Z on purpose: that is 2 March 00:30 in Berlin (winter,
+        // UTC+1). An editor who picked 2 March must get 2 March back -- the date is
+        // the Berlin day, so it must NOT be read as the raw UTC day (1 March).
         await CreateRecordAsync(http, "posts", new
         {
-            date = "2026-03-01 00:00:00.000Z", title = "Neuer Vorstand",
+            date = "2026-03-01 23:30:00.000Z", title = "Neuer Vorstand",
             body = "Text", slug = "new-board", @public = true,
         });
         await CreateRecordAsync(http, "posts", new

docs/redaktion.md

@@ -113,7 +113,9 @@ Ein Beitrag hat `date`, `title`, `body`, `slug` und `public`. Er erscheint unter
 `/posts` (neueste zuerst) und unter `/posts/<slug>`; die neuesten werden auch auf
 der Startseite als Vorschau angeteasert.
 
-- `date` steuert Sortierung und angezeigtes Datum.
+- `date` steuert Sortierung und angezeigtes Datum. Anders als bei Terminen zählt
+  hier nur der **Tag** — eine Uhrzeit wird nie angezeigt, und die UTC-Verschiebung
+  aus dem Termine-Hinweis spielt keine Rolle. Trage einfach das Datum ein.
 - `slug` ist englisch, klein, ohne Umlaute (z. B. `new-sports-hall-opened`).
 
 ---