fix(art): re-seed a bundled background when the stored bytes differ

The creator's profile still showed the previous Starting art after the replacement, with
`Art.DefaultVersion = 4` recorded — so the version gate had already declared itself done. It
compared a constant against the embedded resource, and those two were compiled at different
moments (version 4 landed with the OLD image embedded; the corrected image reached the assembly
one build later). A version bump can always be raced that way.

The seed now compares BYTES: `LayoutStore.AssetMatches` hashes the bundled resource and checks the
row the background already points at. Same bytes → leave it untouched (so this is idempotent and
never churns the database). Different bytes → re-stamp. The version constant and its setting are
gone, because a heal that only runs once can silently skip the one launch it was needed for.

`SceneThumbnailTests` planted its own art on a background still flagged as default art — in the
real app that state only ever means stale bundled art, because Browse… sets the path and clears
the flag. The fixture now models a creator's own picture.

Tests: 572 green, 0 warnings. Verified the profile's Starting asset hash (167CDD3B…, the
two-category render) differs from the shipped `starting-background.jpg` (5FC6DD22…), so the next
launch re-seeds it.

Services/LayoutStore.Assets.cs

@@ -35,6 +35,20 @@ public partial class LayoutStore : IDisposable
         return (string)cmd.ExecuteScalar()!;
     }
 
+    /// <summary>True when the asset already holds exactly these bytes. Used to decide whether a
+    /// bundled image needs re-seeding: comparing bytes cannot go stale the way a version constant
+    /// can (the constant and the embedded resource were built at different moments twice).</summary>
+    public bool AssetMatches(string assetId, byte[] data)
+    {
+        if (string.IsNullOrWhiteSpace(assetId)) return false;
+        var hash = Convert.ToHexString(SHA256.HashData(data));
+        using var cmd = _connection.CreateCommand();
+        cmd.CommandText = "SELECT 1 FROM Asset WHERE Id = $id AND Hash = $hash;";
+        cmd.Parameters.AddWithValue("$id", assetId);
+        cmd.Parameters.AddWithValue("$hash", hash);
+        return cmd.ExecuteScalar() != null;
+    }
+
     // ─── License (TASK 10 — Polar billing) ───
 
     /// <summary>The saved license key, or null if never entered.</summary>

Services/LayoutStore.Settings.cs

@@ -63,12 +63,6 @@ public partial class LayoutStore : IDisposable
 
     public void SaveShowMonetaryMetrics(bool show) => UpsertSetting("Metrics.ShowMonetary", show ? "1" : "0");
 
-    /// <summary>Which vintage of the shipped default scene art this layout was stamped with. Bumped when
-    /// a bundled background is replaced, so existing layouts re-seed instead of keeping the old art.</summary>
-    public int LoadDefaultArtVersion() => int.TryParse(GetSetting("Art.DefaultVersion"), out var v) ? v : 1;
-
-    public void SaveDefaultArtVersion(int version) => UpsertSetting("Art.DefaultVersion", version.ToString());
-
     public bool LoadAutoChromaScreen() => GetSetting("Video.AutoChromaScreen") == "1";
 
     public void SaveAutoChromaScreen(bool enabled) => UpsertSetting("Video.AutoChromaScreen", enabled ? "1" : "0");

ViewModels/MainViewModel.Background.cs

@@ -427,37 +427,9 @@ public partial class MainViewModel
     /// <summary>Heals every scene to the locked Background model after a layout
     /// load: keeps the correct flavor per scene at index 0 named "Background",
     /// drops duplicates/stale rows, re-seeds missing ones.</summary>
-    /// <summary>Bump when a bundled background image is replaced. Layouts stamped with an older version
-    /// re-seed their DEFAULT art on next load; a creator's own custom background is never touched.</summary>
-    private const int CurrentDefaultArtVersion = 4;
-
-    /// <summary>Re-stamp the shipped art for scenes still using the default. Without this, a replaced
-    /// <c>starting-background.jpg</c> reaches new installs only: the asset is hash-keyed into the layout
-    /// database on first seed, so an existing profile keeps showing the old image forever.</summary>
-    private void HealDefaultArtVersion()
-    {
-        if (_layoutStore.LoadDefaultArtVersion() >= CurrentDefaultArtVersion) return;
-
-        // Every scene's background, not AllBackgrounds(): that helper only returns the LIVE scene's
-        // capture-flavoured rows, which is why version 2 healed nothing (2026-11-06).
-        var cleared = 0;
-        foreach (var scene in Scenes)
-        foreach (var background in scene.Elements.OfType<Source>().Where(element => element.IsBackground))
-        {
-            if (!background.UseDefaultBackground && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath))
-                continue;                                     // the creator chose their own art
-            background.AssetId = null;                        // the seed below re-stamps the bundled art
-            cleared++;
-        }
-
-        AppLog.Write($"Default art version {CurrentDefaultArtVersion}: re-seeding {cleared} background(s)");
-        _layoutStore.SaveDefaultArtVersion(CurrentDefaultArtVersion);
-    }
-
     private void HealBackgrounds()
     {
         NormalizeBackgrounds(Scenes);
-        HealDefaultArtVersion();
         foreach (var scene in Scenes)
         {
             _sceneGraph.InvalidateBake(scene);
@@ -516,7 +488,6 @@ public partial class MainViewModel
     /// carries none. A custom image (Browse…) always wins and is never overwritten.</summary>
     private void StampDefaultBackgroundAsset(Source background, string sceneName)
     {
-        if (!string.IsNullOrWhiteSpace(background.AssetId)) return;
         if (!background.UseDefaultBackground && !string.IsNullOrWhiteSpace(background.CustomBackgroundPath)) return;
         var asset = DefaultBackgroundAsset(sceneName);
         if (asset == null) return;
@@ -531,7 +502,13 @@ public partial class MainViewModel
             if (stream == null) return;
             using var ms = new MemoryStream();
             stream.CopyTo(ms);
-            background.AssetId = AddAsset(ms.ToArray());
+            var bytes = ms.ToArray();
+
+            // Already the shipped art → leave it. Compared by BYTES, not by a version stamp: assets are
+            // hash-keyed on first seed, so a replaced bundled image never reaches an existing profile on
+            // its own, and the version constant proved just as stale (2026-11-06).
+            if (_layoutStore.AssetMatches(background.AssetId!, bytes)) return;
+            background.AssetId = AddAsset(bytes);
         }
         catch { /* non-critical — the app works without default art */ }
     }

ytLive.Tests/BackgroundDefaultArtTests.cs

@@ -10,9 +10,10 @@ namespace ytLive.Tests;
 
 /// <summary>
 /// 2026-11-06: replacing a bundled background reached new installs only. Default art is hash-keyed into the
-/// layout database on first seed, so an existing profile kept the old image for ever — and the first
-/// attempt at a version heal silently did nothing because it iterated `AllBackgrounds()`, which returns
-/// only the LIVE scene's rows.
+/// layout database on first seed, so an existing profile kept the old image for ever. A version-stamp heal
+/// failed twice (first it iterated `AllBackgrounds()`, which returns only the LIVE scene's rows; then the
+/// constant and the embedded resource were built at different moments). The seed now compares BYTES, which
+/// is what this test pins: a profile already pointing at other art is re-stamped without any version bump.
 /// </summary>
 [Collection("RealApp")]
 public sealed class BackgroundDefaultArtTests
@@ -35,8 +36,8 @@ public sealed class BackgroundDefaultArtTests
             Assert.False(string.IsNullOrWhiteSpace(firstId), "the bundled Starting art never seeded");
             var firstBytes = AssetLength(tempDb, firstId!);
 
-            // Simulate a profile stamped with the OLD art: point the Starting background at a planted
-            // asset and mark the layout as an older art vintage. The heal must re-stamp the shipped art.
+            // Simulate a profile stamped with the OLD art. No version flag is touched — the seed has to
+            // notice the bytes are not the shipped ones by itself.
             using (var connection = new SqliteConnection($"Data Source={tempDb}"))
             {
                 connection.Open();
@@ -49,8 +50,6 @@ public sealed class BackgroundDefaultArtTests
                 plant.ExecuteNonQuery();
             }
             SqliteConnection.ClearAllPools();
-            using (var store = new LayoutStore(tempDb))
-                store.SaveDefaultArtVersion(1);
 
             var second = new MainViewModel();
             var secondId = StartingBackgroundId(second);
@@ -64,6 +63,10 @@ public sealed class BackgroundDefaultArtTests
                 AppContext.BaseDirectory, "..", "..", "..", "..", "Assets", "starting-background.jpg")).Length,
                 AssetLength(tempDb, secondId!));
             Assert.NotEqual(firstBytes, 0);
+
+            // Idempotent: a third launch finds the shipped bytes already in place and must not re-seed.
+            var third = new MainViewModel();
+            Assert.Equal(secondId, StartingBackgroundId(third));
         }
         finally
         {

ytLive.Tests/SceneThumbnailTests.cs

@@ -263,6 +263,11 @@ public sealed class SceneThumbnailTests
                 var id = LayoutStore.Instance!.UpsertAsset(bytes, 320, 180);
                 Assert.NotNull(id);
                 bg!.AssetId = id;
+                // The creator's own picture, not the shipped art: a default-art background pointing at
+                // other bytes is re-seeded by StampDefaultBackgroundAsset (2026-11-06), and this fixture
+                // needs its planted art to stay put. Browse… always sets the path alongside the asset.
+                bg.UseDefaultBackground = false;
+                bg.CustomBackgroundPath = Path.Combine(Path.GetTempPath(), $"ytLive-missing-{i}.jpg");
                 backgroundIds[scene.Name] = id;
             }
             builder.SaveLayoutNow();