diff --git a/src/api/SIGCM2.Application/Rubros/Create/CreateRubroCommandHandler.cs b/src/api/SIGCM2.Application/Rubros/Create/CreateRubroCommandHandler.cs
index 7332524..f142877 100644
--- a/src/api/SIGCM2.Application/Rubros/Create/CreateRubroCommandHandler.cs
+++ b/src/api/SIGCM2.Application/Rubros/Create/CreateRubroCommandHandler.cs
@@ -14,17 +14,20 @@ public sealed class CreateRubroCommandHandler : ICommandHandler<CreateRubroComma
     private readonly IAuditLogger _audit;
     private readonly TimeProvider _timeProvider;
     private readonly RubrosOptions _options;
+    private readonly IAvisoQueryRepository _avisoQuery;
 
     public CreateRubroCommandHandler(
         IRubroRepository repo,
         IAuditLogger audit,
         TimeProvider timeProvider,
-        IOptions<RubrosOptions> options)
+        IOptions<RubrosOptions> options,
+        IAvisoQueryRepository avisoQuery)
     {
         _repo = repo;
         _audit = audit;
         _timeProvider = timeProvider;
         _options = options.Value;
+        _avisoQuery = avisoQuery;
     }
 
     public async Task<RubroCreatedDto> Handle(CreateRubroCommand command)
@@ -38,6 +41,12 @@ public sealed class CreateRubroCommandHandler : ICommandHandler<CreateRubroComma
             if (!parent.Activo)
                 throw new RubroPadreInactivoException(command.ParentId.Value);
 
+            // CAT-002: Regla de Oro — padre no puede ser hoja con avisos
+            // CAT-002/PRD-002 TOCTOU — evaluar upgrade a RepeatableRead o constraint DB cuando exista dbo.Aviso
+            var avisosCount = await _avisoQuery.CountAvisosEnRubroAsync(command.ParentId.Value);
+            if (avisosCount > 0)
+                throw new RubroPadreEsHojaConAvisosException(command.ParentId.Value, avisosCount);
+
             // Depth check: parent's depth + 1 must not exceed MaxDepth
             var parentDepth = await _repo.GetDepthAsync(command.ParentId);
             var newDepth = parentDepth + 1;
diff --git a/tests/SIGCM2.Application.Tests/Rubros/Create/CreateRubroCommandHandlerTests.cs b/tests/SIGCM2.Application.Tests/Rubros/Create/CreateRubroCommandHandlerTests.cs
index f4b4798..6181380 100644
--- a/tests/SIGCM2.Application.Tests/Rubros/Create/CreateRubroCommandHandlerTests.cs
+++ b/tests/SIGCM2.Application.Tests/Rubros/Create/CreateRubroCommandHandlerTests.cs
@@ -18,6 +18,7 @@ public class CreateRubroCommandHandlerTests
     private readonly IAuditLogger _audit = Substitute.For<IAuditLogger>();
     private readonly FakeTimeProvider _timeProvider = new(new DateTimeOffset(2026, 4, 18, 12, 0, 0, TimeSpan.Zero));
     private readonly IOptions<RubrosOptions> _options = Options.Create(new RubrosOptions { MaxDepth = 10 });
+    private readonly IAvisoQueryRepository _avisoQuery = Substitute.For<IAvisoQueryRepository>();
     private readonly CreateRubroCommandHandler _handler;
 
     public CreateRubroCommandHandlerTests()
@@ -30,8 +31,11 @@ public class CreateRubroCommandHandlerTests
              .Returns(1);
         _repo.GetDepthAsync(Arg.Any<int?>(), Arg.Any<CancellationToken>())
              .Returns(0);
+        // Default: no avisos (stub behavior)
+        _avisoQuery.CountAvisosEnRubroAsync(Arg.Any<int>(), Arg.Any<CancellationToken>())
+                   .Returns(0);
 
-        _handler = new CreateRubroCommandHandler(_repo, _audit, _timeProvider, _options);
+        _handler = new CreateRubroCommandHandler(_repo, _audit, _timeProvider, _options, _avisoQuery);
     }
 
     private static CreateRubroCommand RootCommand() => new("Autos", ParentId: null, TarifarioBaseId: null);
@@ -173,4 +177,76 @@ public class CreateRubroCommandHandlerTests
 
         result.Id.Should().Be(99);
     }
+
+    // ── CAT-002: Guard padre sin avisos ──────────────────────────────────────
+
+    [Fact]
+    public async Task Handle_ParentTieneAvisos_Throws_RubroPadreEsHojaConAvisosException()
+    {
+        const int parentId = 5;
+        var parent = new Rubro(parentId, null, "ParentConAvisos", 0, activo: true, tarifarioBaseId: null,
+            fechaCreacion: DateTime.UtcNow, fechaModificacion: null);
+        _repo.GetByIdAsync(parentId, Arg.Any<CancellationToken>()).Returns(parent);
+        _avisoQuery.CountAvisosEnRubroAsync(parentId, Arg.Any<CancellationToken>()).Returns(3);
+
+        var act = () => _handler.Handle(ChildCommand(parentId: parentId));
+
+        await act.Should().ThrowAsync<RubroPadreEsHojaConAvisosException>()
+            .Where(ex => ex.ParentId == parentId && ex.CantidadAvisos == 3);
+    }
+
+    [Fact]
+    public async Task Handle_ParentTieneCeroAvisos_DoesNotThrow()
+    {
+        const int parentId = 5;
+        var parent = new Rubro(parentId, null, "ParentSinAvisos", 0, activo: true, tarifarioBaseId: null,
+            fechaCreacion: DateTime.UtcNow, fechaModificacion: null);
+        _repo.GetByIdAsync(parentId, Arg.Any<CancellationToken>()).Returns(parent);
+        _avisoQuery.CountAvisosEnRubroAsync(parentId, Arg.Any<CancellationToken>()).Returns(0);
+        _repo.AddAsync(Arg.Any<Rubro>(), Arg.Any<CancellationToken>()).Returns(10);
+
+        var result = await _handler.Handle(ChildCommand(parentId: parentId));
+
+        result.Id.Should().Be(10);
+    }
+
+    [Fact]
+    public async Task Handle_ParentNull_SkipsAvisosGuard()
+    {
+        // Root creation — no parent → CountAvisosEnRubroAsync should NOT be called
+        await _handler.Handle(RootCommand());
+
+        await _avisoQuery.DidNotReceive().CountAvisosEnRubroAsync(Arg.Any<int>(), Arg.Any<CancellationToken>());
+    }
+
+    [Fact]
+    public async Task Handle_GuardOrder_ParentInactivo_Wins_OverAvisos()
+    {
+        // Inactive parent with avisos → RubroPadreInactivoException (not avisos exception)
+        const int parentId = 7;
+        var inactiveParent = new Rubro(parentId, null, "InactivoConAvisos", 0, activo: false, tarifarioBaseId: null,
+            fechaCreacion: DateTime.UtcNow, fechaModificacion: null);
+        _repo.GetByIdAsync(parentId, Arg.Any<CancellationToken>()).Returns(inactiveParent);
+        _avisoQuery.CountAvisosEnRubroAsync(parentId, Arg.Any<CancellationToken>()).Returns(3);
+
+        var act = () => _handler.Handle(ChildCommand(parentId: parentId));
+
+        await act.Should().ThrowAsync<RubroPadreInactivoException>();
+    }
+
+    [Fact]
+    public async Task Handle_GuardOrder_Avisos_Wins_OverDepth()
+    {
+        // Parent at MAX_DEPTH AND has avisos → RubroPadreEsHojaConAvisosException (avisos guard fires first)
+        const int parentId = 5;
+        var parent = new Rubro(parentId, null, "ParentAtMaxDepth", 0, activo: true, tarifarioBaseId: null,
+            fechaCreacion: DateTime.UtcNow, fechaModificacion: null);
+        _repo.GetByIdAsync(parentId, Arg.Any<CancellationToken>()).Returns(parent);
+        _avisoQuery.CountAvisosEnRubroAsync(parentId, Arg.Any<CancellationToken>()).Returns(2);
+        _repo.GetDepthAsync(parentId, Arg.Any<CancellationToken>()).Returns(10); // at MaxDepth
+
+        var act = () => _handler.Handle(ChildCommand(parentId: parentId));
+
+        await act.Should().ThrowAsync<RubroPadreEsHojaConAvisosException>();
+    }
 }