feat: Enhance room image handling by introducing default image and updating display logic; add unit tests for image resolution

.gitignore

@@ -88,3 +88,4 @@ Recovered(*)/
 local-releases/**
 DorkNet.Models/bin-verify/**
 DorkNet.Models/bin-verify2/**
+identityserver-signing.pfx

DorkNet.Server.Tests/RoomServiceTests.cs

@@ -0,0 +1,39 @@
+using System.Text.Json;
+using DorkNet.Server.Data.Entities;
+using DorkNet.Server.Services;
+
+namespace DorkNet.Server.Tests;
+
+public sealed class RoomServiceTests
+{
+    [Fact]
+    public void ToWireRoom_never_emits_empty_image_name()
+    {
+        var room = new RoomEntity
+        {
+            Id = 1001,
+            Name = "CustomRoomWithoutImage",
+            Description = "Custom room",
+            ImageName = "",
+            Accessibility = 1,
+            State = 0,
+        };
+
+        var json = JsonSerializer.Serialize(RoomService.ToWireRoom(room));
+        using var document = JsonDocument.Parse(json);
+
+        Assert.Equal(RoomService.DefaultRoomImageName, document.RootElement.GetProperty("ImageName").GetString());
+    }
+
+    [Fact]
+    public void ResolveDisplayImageName_preserves_existing_image_name()
+    {
+        var room = new RoomEntity
+        {
+            Name = "Paintball",
+            ImageName = "custom-thumbnail.png",
+        };
+
+        Assert.Equal("custom-thumbnail.png", RoomService.ResolveDisplayImageName(room));
+    }
+}

DorkNet.Server/Controllers/API/CommunityBoard/CommunityBoardController.cs

@@ -65,7 +65,6 @@ public class CommunityBoardController(
                 ? new()
                 : await db.Rooms
                     .Where(r => ids.Contains(r.Id))
-                    .Select(r => new { r.Id, r.Name, r.ImageName })
                     .ToDictionaryAsync(r => r.Id);
             // 2020.12 FeaturedRoomGroup deserializer (NMPFCIJPODA.PPGFHEDFBEA)
             // reads required keys: FeaturedRoomGroupId, Name, Rooms (NOT
@@ -76,13 +75,13 @@ public class CommunityBoardController(
                 FeaturedRoomGroupId = 0L,
                 Name = group.Name ?? string.Empty,
                 Rooms = ids.Select(id => rooms.TryGetValue(id, out var r)
-                    ? new { RoomName = r.Name, RoomId = r.Id, ImageName = r.ImageName ?? string.Empty }
+                    ? new { RoomName = r.Name, RoomId = r.Id, ImageName = RoomService.ResolveDisplayImageName(r) }
-                    : new { RoomName = string.Empty, RoomId = id, ImageName = string.Empty })
+                    : new { RoomName = string.Empty, RoomId = id, ImageName = RoomService.DefaultRoomImageName })
                     .ToArray(),
                 // Keep the old key around for any 2020.03 clients hitting prod.
                 FeaturedRooms = ids.Select(id => rooms.TryGetValue(id, out var r)
-                    ? new { RoomName = r.Name, RoomId = r.Id, ImageName = r.ImageName ?? string.Empty }
+                    ? new { RoomName = r.Name, RoomId = r.Id, ImageName = RoomService.ResolveDisplayImageName(r) }
-                    : new { RoomName = string.Empty, RoomId = id, ImageName = string.Empty })
+                    : new { RoomName = string.Empty, RoomId = id, ImageName = RoomService.DefaultRoomImageName })
                     .ToArray(),
             };
         }

DorkNet.Server/Services/RoomService.cs

@@ -11,6 +11,8 @@ namespace DorkNet.Server.Services;
 /// </summary>
 public class RoomService(DorkNetDbContext db)
 {
+    public const string DefaultRoomImageName = "image_RecCenter.png";
+
     /// <summary>
     /// Idempotent seed of the well-known Rec Room Original rooms — pulled
     /// from the AGRoomRuntimeConfig.Locations array we walked in
@@ -232,7 +234,6 @@ public class RoomService(DorkNetDbContext db)
         // image/<blob-name> keys, so do NOT require the mapped blob
         // filename to exist on local disk before using it. Local disk
         // is only a fallback for rooms with no blob-name mapping.
-        const string ultimateFallback = "image_RecCenter.png";
         var imagesDir = Path.Combine(AppContext.BaseDirectory, "data", "images");
         bool OnDisk(string name) =>
             !string.IsNullOrEmpty(name) && File.Exists(Path.Combine(imagesDir, name));
@@ -248,7 +249,7 @@ public class RoomService(DorkNetDbContext db)
             else if (OnDisk(r.ImageName))
                 preferred = r.ImageName;
             else
-                preferred = ultimateFallback;
+                preferred = DefaultRoomImageName;
 
             if (r.ImageName != preferred)
             {
@@ -1085,7 +1086,7 @@ public class RoomService(DorkNetDbContext db)
         Description = r.Description,
         CreatorPlayerId = r.CreatorPlayerId,
         CreatorAccountId = r.CreatorPlayerId,
-        ImageName = r.ImageName,
+        ImageName = ResolveDisplayImageName(r),
         State = r.State,
         Accessibility = r.Accessibility,
         SupportsLevelVoting = r.SupportsLevelVoting,
@@ -1129,6 +1130,16 @@ public class RoomService(DorkNetDbContext db)
         },
     };
 
+    public static string ResolveDisplayImageName(RoomEntity r)
+    {
+        if (!string.IsNullOrWhiteSpace(r.ImageName))
+            return r.ImageName;
+
+        return RoomImagesByName.TryGetValue(r.Name, out var imageName) && !string.IsNullOrWhiteSpace(imageName)
+            ? imageName
+            : DefaultRoomImageName;
+    }
+
     /// <summary>
     /// Idempotent admin overrides applied AFTER SeedAsync. Keeps the seed
     /// table itself untouched (so a clean DB build still seeds the