LITTER-MORTALITY: DeathsWithin8Weeks field (Frühsterblichkeit)

Litter.DeathsWithin8Weeks (int?, nullable). LitterDto + LitterInput extended.
Validation: negative → 400, > TotalBorn → 400 (skipped when TotalBorn null).
Migration AddLitterMortality (additive, nullable). 5 new tests. 194/194 green.
Contract: camelCase field deathsWithin8Weeks in LitterDto/LitterInput.

GerbilManager.Tests/LitterMortalityTests.cs

@@ -0,0 +1,88 @@
+using System.Net;
+using System.Net.Http.Json;
+using System.Text.Json;
+
+namespace GerbilManager.Tests;
+
+/// <summary>LITTER-MORTALITY: deathsWithin8Weeks field — round-trip, validation, null default.</summary>
+public class LitterMortalityTests : IClassFixture<ApiFactory>
+{
+    private readonly HttpClient _client;
+    public LitterMortalityTests(ApiFactory factory) => _client = factory.CreateClient();
+
+    private static int? GetInt(JsonElement el, string prop) =>
+        el.TryGetProperty(prop, out var v) && v.ValueKind == JsonValueKind.Number
+            ? v.GetInt32() : null;
+
+    private async Task<JsonElement> CreateAndGet(object body)
+    {
+        var post = await _client.PostAsJsonAsync("/litters", body);
+        post.EnsureSuccessStatusCode();
+        var idStr = JsonDocument.Parse(await post.Content.ReadAsStringAsync()).RootElement
+            .GetProperty("id").GetString()!;
+        return JsonDocument.Parse(await _client.GetStringAsync($"/litters/{idStr}")).RootElement;
+    }
+
+    [Fact]
+    public async Task DeathsWithin8Weeks_round_trips()
+    {
+        var el = await CreateAndGet(new
+        {
+            name = "Wurf Mortalitätstest",
+            date = "2026-05-01",
+            totalBorn = 6,
+            deathsWithin8Weeks = 2,
+        });
+        Assert.Equal(6, GetInt(el, "totalBorn"));
+        Assert.Equal(2, GetInt(el, "deathsWithin8Weeks"));
+    }
+
+    [Fact]
+    public async Task DeathsWithin8Weeks_defaults_null()
+    {
+        var el = await CreateAndGet(new { name = "Wurf Kein Mort", date = "2026-05-02" });
+        Assert.True(el.TryGetProperty("deathsWithin8Weeks", out var v));
+        Assert.Equal(JsonValueKind.Null, v.ValueKind);
+    }
+
+    [Fact]
+    public async Task DeathsWithin8Weeks_exceeding_TotalBorn_returns_400()
+    {
+        var resp = await _client.PostAsJsonAsync("/litters", new
+        {
+            name = "Ungültig",
+            date = "2026-05-03",
+            totalBorn = 4,
+            deathsWithin8Weeks = 5,
+        });
+        Assert.Equal(HttpStatusCode.BadRequest, resp.StatusCode);
+        var body = await resp.Content.ReadAsStringAsync();
+        Assert.Contains("TotalBorn", body);
+    }
+
+    [Fact]
+    public async Task Negative_DeathsWithin8Weeks_returns_400()
+    {
+        var resp = await _client.PostAsJsonAsync("/litters", new
+        {
+            name = "Negativ",
+            date = "2026-05-04",
+            deathsWithin8Weeks = -1,
+        });
+        Assert.Equal(HttpStatusCode.BadRequest, resp.StatusCode);
+        var body = await resp.Content.ReadAsStringAsync();
+        Assert.Contains("negativ", body);
+    }
+
+    [Fact]
+    public async Task DeathsWithin8Weeks_allowed_when_TotalBorn_null()
+    {
+        var el = await CreateAndGet(new
+        {
+            name = "Kein TotalBorn",
+            date = "2026-05-05",
+            deathsWithin8Weeks = 3,
+        });
+        Assert.Equal(3, GetInt(el, "deathsWithin8Weeks"));
+    }
+}

GerbilManagerWebAPI/Dtos/ApiDtos.cs

@@ -36,6 +36,7 @@ namespace GerbilManagerWebAPI.Dtos
         string Name,
         DateOnly Date,
         int? TotalBorn,
+        int? DeathsWithin8Weeks,
         Guid? FatherId,
         Guid? MotherId,
         DateOnly? ExpectedGoHomeDate,
@@ -85,6 +86,7 @@ namespace GerbilManagerWebAPI.Dtos
         string Name,
         DateOnly Date,
         int? TotalBorn,
+        int? DeathsWithin8Weeks,
         Guid? FatherId,
         Guid? MotherId,
         DateOnly? ExpectedGoHomeDate,

GerbilManagerWebAPI/Endpoints/LitterEndpoints.cs

@@ -23,10 +23,12 @@ namespace GerbilManagerWebAPI.Endpoints
                 return l is null ? TypedResults.NotFound() : TypedResults.Ok(ToDto(l));
             });
 
-            group.MapPost("/", async Task<Results<Created<LitterDto>, BadRequest<ParentGenderError>>> (LitterInput input, ApplicationContext db) =>
+            group.MapPost("/", async Task<Results<Created<LitterDto>, BadRequest<ParentGenderError>, BadRequest<string>>> (LitterInput input, ApplicationContext db) =>
             {
                 var err = await ValidateParents(db, input.FatherId, input.MotherId);
                 if (err is not null) return TypedResults.BadRequest(err);
+                var mortalityErr = ValidateMortality(input.DeathsWithin8Weeks, input.TotalBorn);
+                if (mortalityErr is not null) return TypedResults.BadRequest(mortalityErr);
 
                 var l = new Litter { Id = Guid.NewGuid(), Name = input.Name, Date = input.Date };
                 Apply(l, input);
@@ -35,12 +37,14 @@ namespace GerbilManagerWebAPI.Endpoints
                 return TypedResults.Created($"/litters/{l.Id}", ToDto(l));
             });
 
-            group.MapPut("/{id:guid}", async Task<Results<NoContent, NotFound, BadRequest<ParentGenderError>>> (Guid id, LitterInput input, ApplicationContext db) =>
+            group.MapPut("/{id:guid}", async Task<Results<NoContent, NotFound, BadRequest<ParentGenderError>, BadRequest<string>>> (Guid id, LitterInput input, ApplicationContext db) =>
             {
                 var l = await db.Litters.FirstOrDefaultAsync(x => x.Id == id);
                 if (l is null) return TypedResults.NotFound();
                 var err = await ValidateParents(db, input.FatherId, input.MotherId);
                 if (err is not null) return TypedResults.BadRequest(err);
+                var mortalityErr = ValidateMortality(input.DeathsWithin8Weeks, input.TotalBorn);
+                if (mortalityErr is not null) return TypedResults.BadRequest(mortalityErr);
                 l.Name = input.Name;
                 l.Date = input.Date;
                 Apply(l, input);
@@ -76,14 +80,25 @@ namespace GerbilManagerWebAPI.Endpoints
         private static void Apply(Litter l, LitterInput i)
         {
             l.TotalBorn = i.TotalBorn;
+            l.DeathsWithin8Weeks = i.DeathsWithin8Weeks;
             l.FatherId = i.FatherId;
             l.MotherId = i.MotherId;
             l.ExpectedGoHomeDate = i.ExpectedGoHomeDate;
             l.Notes = i.Notes;
         }
 
+        private static string? ValidateMortality(int? deaths, int? totalBorn)
+        {
+            if (deaths is null) return null;
+            if (deaths < 0) return "DeathsWithin8Weeks darf nicht negativ sein.";
+            if (totalBorn is not null && deaths > totalBorn)
+                return "DeathsWithin8Weeks darf nicht größer als TotalBorn sein.";
+            return null;
+        }
+
         private static LitterDto ToDto(Litter l) => new(
-            l.Id, l.Name, l.Date, l.TotalBorn, l.FatherId, l.MotherId, l.ExpectedGoHomeDate, l.Notes);
+            l.Id, l.Name, l.Date, l.TotalBorn, l.DeathsWithin8Weeks,
+            l.FatherId, l.MotherId, l.ExpectedGoHomeDate, l.Notes);
     }
 
     /// <summary>400 body for a father×mother gender mismatch; frontend localises by Code.</summary>

GerbilManagerWebAPI/Migrations/20260607013052_AddLitterMortality.cs

@@ -0,0 +1,28 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace GerbilManagerWebAPI.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddLitterMortality : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "DeathsWithin8Weeks",
+                table: "Litters",
+                type: "integer",
+                nullable: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "DeathsWithin8Weeks",
+                table: "Litters");
+        }
+    }
+}

GerbilManagerWebAPI/Migrations/ApplicationContextModelSnapshot.cs

@@ -924,6 +924,9 @@ namespace GerbilManagerWebAPI.Migrations
                     b.Property<DateOnly>("Date")
                         .HasColumnType("date");
 
+                    b.Property<int?>("DeathsWithin8Weeks")
+                        .HasColumnType("integer");
+
                     b.Property<DateOnly?>("ExpectedGoHomeDate")
                         .HasColumnType("date");
 

GerbilManagerWebAPI/Models/Litter.cs

@@ -13,6 +13,10 @@ namespace GerbilManagerWebAPI.Models
         /// <summary>Total born count (was "Strength").</summary>
         public int? TotalBorn { get; set; }
 
+        /// <summary>Frühsterblichkeit: Anzahl der in den ersten 8 Wochen verstorbenen Tiere.
+        /// Null = unbekannt (Altdaten). Must be ≤ TotalBorn if both are set.</summary>
+        public int? DeathsWithin8Weeks { get; set; }
+
         public Guid? FatherId { get; set; }
         public Gerbil? Father { get; set; }
         public Guid? MotherId { get; set; }