test(67): de-vacuify the template-stamping assertion; cover adopt-then-delete

Whole-branch review found the stamping test was structurally vacuous: a bare
foreach over ChannelTemplates.Where(IsSystem) passes with zero iterations, so
the test would have stayed green if template seeding silently bailed out.
Assert the collection is non-empty first. Proven non-vacuous by a negative
control (forcing SeedChannelTemplates to bail makes exactly this test fail).

Also cover the ACTUAL production sequence -- adopt an existing hand-made row,
then delete it -- which the previous no-resurrect test did not exercise (it
covered seed-then-delete). The marker is written on the adopt path too, so
the deleted row must stay deleted.

docs: note that a deleted preset degrades to no default rather than failing,
and that the default applies to newly created channels, not retroactively.

Refs #67

ErsatzTV.Tests/Infrastructure/DbInitializerChannelBugWatermarkTests.cs

@@ -99,6 +99,37 @@ public class DbInitializerChannelBugWatermarkTests
         context.ChannelWatermarks.Any(w => w.Name == "Channel Bug").ShouldBeFalse();
     }
 
+    // The production sequence is ADOPT (an existing hand-made row) and then, possibly, delete —
+    // not seed-then-delete. The marker is written on the adopt path too, so this must not resurrect.
+    [Test]
+    public async Task Initialize_Should_Not_Resurrect_An_Adopted_Preset_After_Deletion()
+    {
+        await using TvContext context = _db.CreateContext();
+        await context.ChannelWatermarks.AddAsync(
+            new ChannelWatermark
+            {
+                Name = "Channel Bug",
+                Mode = ChannelWatermarkMode.Permanent,
+                ImageSource = ChannelWatermarkImageSource.ChannelLogo,
+                Location = WatermarkLocation.BottomRight,
+                Size = WatermarkSize.Scaled,
+                WidthPercent = 12,
+                Opacity = 55
+            });
+        await context.SaveChangesAsync();
+
+        // First run adopts the existing row and records the marker.
+        await DbInitializer.Initialize(context, CancellationToken.None);
+
+        ChannelWatermark adopted = context.ChannelWatermarks.Single(w => w.Name == "Channel Bug");
+        context.ChannelWatermarks.Remove(adopted);
+        await context.SaveChangesAsync();
+
+        await DbInitializer.Initialize(context, CancellationToken.None);
+
+        context.ChannelWatermarks.Any(w => w.Name == "Channel Bug").ShouldBeFalse();
+    }
+
     [Test]
     public async Task Initialize_Should_Stamp_The_Preset_On_Freshly_Seeded_Templates()
     {
@@ -107,7 +138,12 @@ public class DbInitializerChannelBugWatermarkTests
         await DbInitializer.Initialize(context, CancellationToken.None);
 
         ChannelWatermark watermark = context.ChannelWatermarks.Single(w => w.Name == "Channel Bug");
-        foreach (ChannelTemplate template in context.ChannelTemplates.Where(t => t.IsSystem).ToList())
+        List<ChannelTemplate> templates = context.ChannelTemplates.Where(t => t.IsSystem).ToList();
+
+        // Assert the collection is non-empty FIRST: a bare foreach over zero rows passes vacuously,
+        // so this test would stay green if template seeding silently bailed out.
+        templates.Count.ShouldBe(2);
+        foreach (ChannelTemplate template in templates)
         {
             template.WatermarkId.ShouldBe(watermark.Id);
         }

docs/channels.md

@@ -154,8 +154,11 @@ listing and the bug (#67). An existing `Channel Bug` row is adopted untouched, n
 a `ConfigElement` marker (`watermark.channel_bug_seeded`) makes the seed run once per database, so a
 deliberately deleted preset is not resurrected on the next restart.
 
-Quick-add channel creation defaults to the preset, and the channel editor's Branding tab exposes it
-as a "Use logo as on-screen bug" toggle. On a **fresh** install the seed also stamps the preset onto
+Quick-add channel creation defaults to the preset (if the preset has been deleted, creation falls
+back to no watermark rather than failing), and the channel editor's Branding tab exposes it as a
+"Use logo as on-screen bug" toggle. The default applies to **newly created** channels — an existing
+channel with no watermark does not gain one retroactively when a logo is uploaded; flip the toggle.
+On a **fresh** install the seed also stamps the preset onto
 the system channel templates it creates, so the library-to-lineup builder (which inherits
 `WatermarkId` from the selected template) gets the default too. On an existing install the templates
 are left alone, so builder-created and auto-tuned channels there inherit whatever the template