feat(ui): add inheritance resolver returning value and source

tests/ClaudeDo.Ui.Tests/InheritanceResolverTests.cs

@@ -0,0 +1,43 @@
+using ClaudeDo.Ui.Services;
+using Xunit;
+
+namespace ClaudeDo.Ui.Tests;
+
+public class InheritanceResolverTests
+{
+    [Fact]
+    public void Task_value_is_an_override()
+    {
+        var (value, source) = InheritanceResolver.Resolve("opus", "sonnet", "haiku");
+        Assert.Equal("opus", value);
+        Assert.Equal(InheritSource.Override, source);
+    }
+
+    [Fact]
+    public void Falls_through_to_list()
+    {
+        var (value, source) = InheritanceResolver.Resolve(null, "sonnet", "haiku");
+        Assert.Equal("sonnet", value);
+        Assert.Equal(InheritSource.List, source);
+    }
+
+    [Fact]
+    public void Falls_through_to_global()
+    {
+        var (value, source) = InheritanceResolver.Resolve("  ", null, "haiku");
+        Assert.Equal("haiku", value);
+        Assert.Equal(InheritSource.Global, source);
+    }
+
+    [Fact]
+    public void List_scope_treats_list_value_as_override()
+    {
+        var (value, source) = InheritanceResolver.ResolveList("sonnet", "haiku");
+        Assert.Equal("sonnet", value);
+        Assert.Equal(InheritSource.Override, source);
+
+        var (value2, source2) = InheritanceResolver.ResolveList(null, "haiku");
+        Assert.Equal("haiku", value2);
+        Assert.Equal(InheritSource.Global, source2);
+    }
+}