diff --git a/tests/SIGCM2.Api.Tests/Products/ProductTypeDeactivationGuardTests.cs b/tests/SIGCM2.Api.Tests/Products/ProductTypeDeactivationGuardTests.cs
new file mode 100644
index 0000000..1d244ed
--- /dev/null
+++ b/tests/SIGCM2.Api.Tests/Products/ProductTypeDeactivationGuardTests.cs
@@ -0,0 +1,158 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+using System.Text.Json;
+using SIGCM2.TestSupport;
+
+namespace SIGCM2.Api.Tests.Products;
+
+/// <summary>
+/// PRD-002 Batch 8 — Guard proof: verifies that deactivating a ProductType with active Products
+/// returns HTTP 409 Conflict. This test closes the W1 (dormant guard) issue from PRD-001:
+/// - PRD-001: NullProductQueryRepository always returned false → guard never fired
+/// - PRD-002: ProductQueryRepository now queries dbo.Product → guard fires correctly
+/// </summary>
+[Collection("ApiIntegration")]
+public sealed class ProductTypeDeactivationGuardTests : IAsyncLifetime
+{
+    private const string AdminUsername = "admin";
+    private const string AdminPassword = "@Diego550@";
+
+    private readonly HttpClient _client;
+
+    public ProductTypeDeactivationGuardTests(TestWebAppFactory factory)
+    {
+        _client = factory.CreateClient();
+    }
+
+    public Task InitializeAsync() => Task.CompletedTask;
+    public Task DisposeAsync() => Task.CompletedTask;
+
+    private async Task<string> GetAdminTokenAsync()
+    {
+        var response = await _client.PostAsJsonAsync("/api/v1/auth/login", new
+        {
+            username = AdminUsername,
+            password = AdminPassword
+        });
+        response.EnsureSuccessStatusCode();
+        var json = await response.Content.ReadFromJsonAsync<JsonElement>();
+        return json.GetProperty("accessToken").GetString()!;
+    }
+
+    private HttpRequestMessage BuildRequest(HttpMethod method, string url, object? body = null, string? bearerToken = null)
+    {
+        var request = new HttpRequestMessage(method, url);
+        if (bearerToken is not null)
+            request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", bearerToken);
+        if (body is not null)
+            request.Content = JsonContent.Create(body);
+        return request;
+    }
+
+    /// <summary>
+    /// E2E proof: seed Medio + ProductType + active Product → DELETE product-type → expect 409.
+    /// This verifies the IProductQueryRepository guard fires against real data in dbo.Product.
+    /// </summary>
+    [Fact]
+    public async Task DeactivateProductType_WithActiveProducts_Returns409Conflict()
+    {
+        var token = await GetAdminTokenAsync();
+
+        // 1. Create a Medio
+        var medioResp = await _client.SendAsync(BuildRequest(HttpMethod.Post, "/api/v1/admin/medios", new
+        {
+            codigo = $"GD{Guid.NewGuid():N}"[..6],
+            nombre = $"Guarda Medio {Guid.NewGuid():N}"[..30],
+            tipo = 1
+        }, token));
+        medioResp.EnsureSuccessStatusCode();
+        var medioJson = await medioResp.Content.ReadFromJsonAsync<JsonElement>();
+        var medioId = medioJson.GetProperty("id").GetInt32();
+
+        // 2. Create a ProductType
+        var ptResp = await _client.SendAsync(BuildRequest(HttpMethod.Post, "/api/v1/admin/product-types", new
+        {
+            nombre = $"Guardado PT {Guid.NewGuid():N}"[..30],
+            hasDuration = false, requiresText = false, requiresCategory = false, isBundle = false,
+            allowImages = false
+        }, token));
+        ptResp.EnsureSuccessStatusCode();
+        var ptJson = await ptResp.Content.ReadFromJsonAsync<JsonElement>();
+        var productTypeId = ptJson.GetProperty("id").GetInt32();
+
+        // 3. Create an active Product for this ProductType
+        var prodResp = await _client.SendAsync(BuildRequest(HttpMethod.Post, "/api/v1/admin/products", new
+        {
+            nombre = $"Prod Guarda {Guid.NewGuid():N}"[..28],
+            medioId,
+            productTypeId,
+            basePrice = 100m
+        }, token));
+        prodResp.EnsureSuccessStatusCode();
+
+        // 4. Attempt to deactivate the ProductType — should be blocked by guard
+        using var deactivateReq = BuildRequest(HttpMethod.Delete, $"/api/v1/admin/product-types/{productTypeId}", bearerToken: token);
+        var deactivateResp = await _client.SendAsync(deactivateReq);
+
+        // CRITICAL ASSERTION: 409 Conflict — guard fires because Product is active
+        Assert.Equal(HttpStatusCode.Conflict, deactivateResp.StatusCode);
+
+        var body = await deactivateResp.Content.ReadFromJsonAsync<JsonElement>();
+        Assert.Equal("product_type_en_uso", body.GetProperty("error").GetString());
+    }
+
+    /// <summary>
+    /// Verify guard does NOT block deactivation when Products exist but are all inactive.
+    /// </summary>
+    [Fact]
+    public async Task DeactivateProductType_WithOnlyInactiveProducts_Returns204()
+    {
+        var token = await GetAdminTokenAsync();
+
+        // 1. Create Medio
+        var medioResp = await _client.SendAsync(BuildRequest(HttpMethod.Post, "/api/v1/admin/medios", new
+        {
+            codigo = $"GI{Guid.NewGuid():N}"[..6],
+            nombre = $"Guarda Inact {Guid.NewGuid():N}"[..28],
+            tipo = 1
+        }, token));
+        medioResp.EnsureSuccessStatusCode();
+        var medioJson = await medioResp.Content.ReadFromJsonAsync<JsonElement>();
+        var medioId = medioJson.GetProperty("id").GetInt32();
+
+        // 2. Create ProductType
+        var ptResp = await _client.SendAsync(BuildRequest(HttpMethod.Post, "/api/v1/admin/product-types", new
+        {
+            nombre = $"PT Inact {Guid.NewGuid():N}"[..28],
+            hasDuration = false, requiresText = false, requiresCategory = false, isBundle = false,
+            allowImages = false
+        }, token));
+        ptResp.EnsureSuccessStatusCode();
+        var ptJson = await ptResp.Content.ReadFromJsonAsync<JsonElement>();
+        var productTypeId = ptJson.GetProperty("id").GetInt32();
+
+        // 3. Create then deactivate Product
+        var prodResp = await _client.SendAsync(BuildRequest(HttpMethod.Post, "/api/v1/admin/products", new
+        {
+            nombre = $"Prod Inact {Guid.NewGuid():N}"[..28],
+            medioId,
+            productTypeId,
+            basePrice = 50m
+        }, token));
+        prodResp.EnsureSuccessStatusCode();
+        var prodJson = await prodResp.Content.ReadFromJsonAsync<JsonElement>();
+        var productId = prodJson.GetProperty("id").GetInt32();
+
+        // Deactivate the Product first
+        using var deactivateProdReq = BuildRequest(HttpMethod.Delete, $"/api/v1/admin/products/{productId}", bearerToken: token);
+        var deactivateProdResp = await _client.SendAsync(deactivateProdReq);
+        Assert.Equal(HttpStatusCode.NoContent, deactivateProdResp.StatusCode);
+
+        // 4. Now deactivate ProductType — should succeed since no active products
+        using var deactivatePtReq = BuildRequest(HttpMethod.Delete, $"/api/v1/admin/product-types/{productTypeId}", bearerToken: token);
+        var deactivatePtResp = await _client.SendAsync(deactivatePtReq);
+
+        Assert.Equal(HttpStatusCode.NoContent, deactivatePtResp.StatusCode);
+    }
+}