diff --git a/src/api/SIGCM2.Application/Rubros/Common/RubroTreeBuilder.cs b/src/api/SIGCM2.Application/Rubros/Common/RubroTreeBuilder.cs
index 3e92ddf..04c3fc0 100644
--- a/src/api/SIGCM2.Application/Rubros/Common/RubroTreeBuilder.cs
+++ b/src/api/SIGCM2.Application/Rubros/Common/RubroTreeBuilder.cs
@@ -12,7 +12,8 @@ public static class RubroTreeBuilder
 {
     public static IReadOnlyList<RubroTreeNodeDto> Build(
         IEnumerable<Rubro> flat,
-        bool incluirInactivos)
+        bool incluirInactivos,
+        IReadOnlyDictionary<int, int> avisoCounts)
     {
         var filtered = incluirInactivos
             ? flat.ToList()
@@ -36,6 +37,7 @@ public static class RubroTreeBuilder
                 Activo: r.Activo,
                 ParentId: r.ParentId,
                 TarifarioBaseId: r.TarifarioBaseId,
+                TieneAvisos: avisoCounts.GetValueOrDefault(r.Id, 0) > 0,
                 Hijos: children);
         }
 
diff --git a/src/api/SIGCM2.Application/Rubros/Dtos/RubroTreeNodeDto.cs b/src/api/SIGCM2.Application/Rubros/Dtos/RubroTreeNodeDto.cs
index 1bf5468..2f4d2c6 100644
--- a/src/api/SIGCM2.Application/Rubros/Dtos/RubroTreeNodeDto.cs
+++ b/src/api/SIGCM2.Application/Rubros/Dtos/RubroTreeNodeDto.cs
@@ -10,4 +10,5 @@ public sealed record RubroTreeNodeDto(
     bool Activo,
     int? ParentId,
     int? TarifarioBaseId,
+    bool TieneAvisos,
     IReadOnlyList<RubroTreeNodeDto> Hijos);
diff --git a/src/api/SIGCM2.Application/Rubros/GetTree/GetRubroTreeQueryHandler.cs b/src/api/SIGCM2.Application/Rubros/GetTree/GetRubroTreeQueryHandler.cs
index 6fcefcc..884b869 100644
--- a/src/api/SIGCM2.Application/Rubros/GetTree/GetRubroTreeQueryHandler.cs
+++ b/src/api/SIGCM2.Application/Rubros/GetTree/GetRubroTreeQueryHandler.cs
@@ -17,6 +17,7 @@ public sealed class GetRubroTreeQueryHandler : ICommandHandler<GetRubroTreeQuery
     public async Task<IReadOnlyList<RubroTreeNodeDto>> Handle(GetRubroTreeQuery query)
     {
         var all = await _repo.GetAllAsync(query.IncluirInactivos);
-        return RubroTreeBuilder.Build(all, query.IncluirInactivos);
+        // CAT-002: avisoCounts injected via IAvisoQueryRepository (wired in Batch 6)
+        return RubroTreeBuilder.Build(all, query.IncluirInactivos, new Dictionary<int, int>());
     }
 }
diff --git a/tests/SIGCM2.Application.Tests/Rubros/RubroTreeBuilderTests.cs b/tests/SIGCM2.Application.Tests/Rubros/RubroTreeBuilderTests.cs
index 14e8338..c56aa9a 100644
--- a/tests/SIGCM2.Application.Tests/Rubros/RubroTreeBuilderTests.cs
+++ b/tests/SIGCM2.Application.Tests/Rubros/RubroTreeBuilderTests.cs
@@ -18,7 +18,7 @@ public class RubroTreeBuilderTests
     [Fact]
     public void Build_empty_returns_empty_list()
     {
-        var result = RubroTreeBuilder.Build([], incluirInactivos: false);
+        var result = RubroTreeBuilder.Build([], incluirInactivos: false, new Dictionary<int, int>());
 
         result.Should().BeEmpty();
     }
@@ -30,7 +30,7 @@ public class RubroTreeBuilderTests
     {
         var rubros = new[] { MakeRubro(1, null, "Autos", 0) };
 
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, new Dictionary<int, int>());
 
         result.Should().HaveCount(1);
         result[0].Id.Should().Be(1);
@@ -50,7 +50,7 @@ public class RubroTreeBuilderTests
             MakeRubro(2, null, "Camiones", 1)
         };
 
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, new Dictionary<int, int>());
 
         result.Should().HaveCount(3);
         result[0].Id.Should().Be(1); // Orden=0
@@ -70,7 +70,7 @@ public class RubroTreeBuilderTests
             MakeRubro(3, 2, "Compactos", 0),
         };
 
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, new Dictionary<int, int>());
 
         result.Should().HaveCount(1);
         result[0].Id.Should().Be(1);
@@ -91,7 +91,7 @@ public class RubroTreeBuilderTests
             MakeRubro(2, null, "Motos", 1, activo: false),
         };
 
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, new Dictionary<int, int>());
 
         result.Should().HaveCount(1);
         result[0].Id.Should().Be(1);
@@ -106,7 +106,7 @@ public class RubroTreeBuilderTests
             MakeRubro(2, null, "Motos", 1, activo: false),
         };
 
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: true);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: true, new Dictionary<int, int>());
 
         result.Should().HaveCount(2);
     }
@@ -125,7 +125,7 @@ public class RubroTreeBuilderTests
             MakeRubro(5, 1, "A", 0),
         };
 
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, new Dictionary<int, int>());
 
         var hijos = result[0].Hijos;
         hijos.Should().HaveCount(4);
@@ -135,6 +135,47 @@ public class RubroTreeBuilderTests
         hijos[3].Nombre.Should().Be("D"); // Orden=3
     }
 
+    // ── TieneAvisos from avisoCounts dict ────────────────────────────────────
+
+    [Fact]
+    public void Build_SetsTieneAvisos_True_WhenCountGreaterThanZero()
+    {
+        var rubros = new[]
+        {
+            MakeRubro(1, null, "Autos", 0),
+            MakeRubro(2, null, "Motos", 1),
+        };
+        var avisoCounts = new Dictionary<int, int> { { 1, 2 }, { 2, 0 } };
+
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, avisoCounts);
+
+        result.Single(n => n.Id == 1).TieneAvisos.Should().BeTrue();
+        result.Single(n => n.Id == 2).TieneAvisos.Should().BeFalse();
+    }
+
+    [Fact]
+    public void Build_SetsTieneAvisos_False_WhenCountIsZero()
+    {
+        var rubros = new[] { MakeRubro(1, null, "Autos", 0) };
+        var avisoCounts = new Dictionary<int, int> { { 1, 0 } };
+
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, avisoCounts);
+
+        result[0].TieneAvisos.Should().BeFalse();
+    }
+
+    [Fact]
+    public void Build_SetsTieneAvisos_False_WhenIdMissingFromDict()
+    {
+        // Stub semantics: missing key = 0 = false
+        var rubros = new[] { MakeRubro(1, null, "Autos", 0) };
+        var avisoCounts = new Dictionary<int, int>(); // empty dict
+
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, avisoCounts);
+
+        result[0].TieneAvisos.Should().BeFalse();
+    }
+
     // ── O(n) perf smoke test ──────────────────────────────────────────────────
 
     [Fact]
@@ -148,7 +189,7 @@ public class RubroTreeBuilderTests
             rubros.Add(MakeRubro(i, 1, $"Child{i}", i - 2));
 
         var sw = System.Diagnostics.Stopwatch.StartNew();
-        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false);
+        var result = RubroTreeBuilder.Build(rubros, incluirInactivos: false, new Dictionary<int, int>());
         sw.Stop();
 
         result.Should().HaveCount(1);