diff --git a/src/api/SIGCM2.Api/Controllers/ProductPricesController.cs b/src/api/SIGCM2.Api/Controllers/ProductPricesController.cs
new file mode 100644
index 0000000..b3c8fbc
--- /dev/null
+++ b/src/api/SIGCM2.Api/Controllers/ProductPricesController.cs
@@ -0,0 +1,93 @@
+using FluentValidation;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using SIGCM2.Api.Authorization;
+using SIGCM2.Application.Abstractions;
+using SIGCM2.Application.Products.Prices;
+using SIGCM2.Application.Products.Prices.AddPrice;
+using SIGCM2.Application.Products.Prices.GetHistory;
+
+namespace SIGCM2.Api.Controllers;
+
+/// <summary>
+/// PRD-003: ProductPrices historic pricing management.
+/// Read endpoint at GET /api/v1/products/{id}/prices — requires authentication (any role).
+/// Write endpoint at POST /api/v1/admin/products/{id}/prices — requires 'catalogo:productos:gestionar'.
+/// </summary>
+[ApiController]
+public sealed class ProductPricesController : ControllerBase
+{
+    private readonly IDispatcher _dispatcher;
+    private readonly IValidator<AddProductPriceCommand> _addValidator;
+
+    public ProductPricesController(
+        IDispatcher dispatcher,
+        IValidator<AddProductPriceCommand> addValidator)
+    {
+        _dispatcher = dispatcher;
+        _addValidator = addValidator;
+    }
+
+    // ── READ endpoint ──────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Returns the full price history for a Product, ordered descending by PriceValidFrom.
+    /// Returns 200 with empty array if the product has no prices yet.
+    /// Returns 404 if the product does not exist.
+    /// </summary>
+    [HttpGet("api/v1/products/{id:int}/prices")]
+    [Authorize]
+    [ProducesResponseType(typeof(IReadOnlyList<ProductPriceDto>), StatusCodes.Status200OK)]
+    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    public async Task<IActionResult> GetProductPrices([FromRoute] int id)
+    {
+        var query = new GetProductPricesQuery(id);
+        var result = await _dispatcher.Send<GetProductPricesQuery, IReadOnlyList<ProductPriceDto>>(query);
+        return Ok(result);
+    }
+
+    // ── WRITE endpoint ─────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Adds a new price to a Product. Closes the current active price if one exists.
+    /// PriceValidFrom must be >= today_AR and strictly greater than the active price's PriceValidFrom.
+    /// Returns 201 Created with Location header pointing to GET /api/v1/products/{id}/prices.
+    /// </summary>
+    [HttpPost("api/v1/admin/products/{id:int}/prices")]
+    [RequirePermission("catalogo:productos:gestionar")]
+    [ProducesResponseType(typeof(AddProductPriceResponse), StatusCodes.Status201Created)]
+    [ProducesResponseType(StatusCodes.Status400BadRequest)]
+    [ProducesResponseType(StatusCodes.Status401Unauthorized)]
+    [ProducesResponseType(StatusCodes.Status403Forbidden)]
+    [ProducesResponseType(StatusCodes.Status404NotFound)]
+    [ProducesResponseType(StatusCodes.Status409Conflict)]
+    public async Task<IActionResult> AddProductPrice(
+        [FromRoute] int id,
+        [FromBody] AddProductPriceRequest request)
+    {
+        var command = new AddProductPriceCommand(
+            ProductId: id,
+            Price: request.Price,
+            PriceValidFrom: request.PriceValidFrom);
+
+        var validation = await _addValidator.ValidateAsync(command);
+        if (!validation.IsValid)
+        {
+            var errors = validation.Errors
+                .GroupBy(e => e.PropertyName)
+                .ToDictionary(g => g.Key, g => g.Select(e => e.ErrorMessage).ToArray());
+            return BadRequest(new { errors });
+        }
+
+        var result = await _dispatcher.Send<AddProductPriceCommand, AddProductPriceResponse>(command);
+        return CreatedAtAction(nameof(GetProductPrices), new { id }, result);
+    }
+}
+
+// ── Request body record ───────────────────────────────────────────────────────
+
+/// <summary>PRD-003: Add ProductPrice request body.</summary>
+public sealed record AddProductPriceRequest(
+    decimal Price,
+    DateOnly PriceValidFrom);
diff --git a/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs b/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs
index 8fc1884..9b3602e 100644
--- a/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs
+++ b/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs
@@ -475,6 +475,45 @@ public sealed class ExceptionFilter : IExceptionFilter
                 context.ExceptionHandled = true;
                 break;
 
+            // PRD-003: ProductPrices exceptions
+            case ProductPriceForwardOnlyException forwardOnlyEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "product_price_forward_only",
+                    message = forwardOnlyEx.Message,
+                    productId = forwardOnlyEx.ProductId
+                })
+                {
+                    StatusCode = StatusCodes.Status409Conflict
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case ProductPriceInvalidException priceInvalidEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "product_price_invalid",
+                    message = priceInvalidEx.Message,
+                    field = priceInvalidEx.Field
+                })
+                {
+                    StatusCode = StatusCodes.Status400BadRequest
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case ProductSinPrecioActivoException sinPrecioEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "product_sin_precio_activo",
+                    message = sinPrecioEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status404NotFound
+                };
+                context.ExceptionHandled = true;
+                break;
+
             // PRD-002: Product exceptions
             case ProductNotFoundException productNotFoundEx:
                 context.Result = new ObjectResult(new
diff --git a/src/api/SIGCM2.Application/Products/Prices/AddPrice/AddProductPriceCommandHandler.cs b/src/api/SIGCM2.Application/Products/Prices/AddPrice/AddProductPriceCommandHandler.cs
index 99861ff..d54ee9f 100644
--- a/src/api/SIGCM2.Application/Products/Prices/AddPrice/AddProductPriceCommandHandler.cs
+++ b/src/api/SIGCM2.Application/Products/Prices/AddPrice/AddProductPriceCommandHandler.cs
@@ -44,30 +44,35 @@ public sealed class AddProductPriceCommandHandler
 
         // 2. TX + SP + audit (fail-closed).
         //    El audit.LogAsync enlista en el mismo TransactionScope — si falla, rollback total.
-        using var tx = new TransactionScope(
+        //    GetByProductIdAsync se ejecuta FUERA del scope (post-commit) para evitar
+        //    "TransactionScope is already complete" al abrir una nueva conexión dentro del using.
+        long newId;
+        long? closedId;
+        using (var tx = new TransactionScope(
             TransactionScopeOption.Required,
             new TransactionOptions { IsolationLevel = System.Transactions.IsolationLevel.ReadCommitted },
-            TransactionScopeAsyncFlowOption.Enabled);
+            TransactionScopeAsyncFlowOption.Enabled))
+        {
+            (newId, closedId) = await _pricesRepo.AddAsync(
+                command.ProductId, command.Price, command.PriceValidFrom);
 
-        var (newId, closedId) = await _pricesRepo.AddAsync(
-            command.ProductId, command.Price, command.PriceValidFrom);
-
-        await _audit.LogAsync(
-            action: "product_price.created",
-            targetType: "ProductPrice",
-            targetId: newId.ToString(),
-            metadata: new
-            {
-                after = new
+            await _audit.LogAsync(
+                action: "product_price.created",
+                targetType: "ProductPrice",
+                targetId: newId.ToString(),
+                metadata: new
                 {
-                    command.ProductId,
-                    command.Price,
-                    priceValidFrom = command.PriceValidFrom.ToString("yyyy-MM-dd"),
-                },
-                closedPriceId = closedId
-            });
+                    after = new
+                    {
+                        command.ProductId,
+                        command.Price,
+                        priceValidFrom = command.PriceValidFrom.ToString("yyyy-MM-dd"),
+                    },
+                    closedPriceId = closedId
+                });
 
-        tx.Complete();
+            tx.Complete();
+        } // TX disposed (committed) here — BEFORE the post-commit read below.
 
         // 3. Compongo la respuesta post-commit con lectura de historial actualizado.
         var prices = await _pricesRepo.GetByProductIdAsync(command.ProductId);
diff --git a/tests/SIGCM2.Api.Tests/Products/ProductPricesControllerTests.cs b/tests/SIGCM2.Api.Tests/Products/ProductPricesControllerTests.cs
new file mode 100644
index 0000000..132293f
--- /dev/null
+++ b/tests/SIGCM2.Api.Tests/Products/ProductPricesControllerTests.cs
@@ -0,0 +1,450 @@
+using System.Net;
+using System.Net.Http.Headers;
+using System.Net.Http.Json;
+using System.Text.Json;
+using Dapper;
+using FluentAssertions;
+using Microsoft.Data.SqlClient;
+using Microsoft.Extensions.DependencyInjection;
+using SIGCM2.Application.Abstractions.Security;
+using SIGCM2.Domain.Entities;
+using SIGCM2.TestSupport;
+using Xunit;
+
+namespace SIGCM2.Api.Tests.Products;
+
+/// <summary>
+/// PRD-003 — Integration tests for:
+///   GET  /api/v1/products/{id}/prices       (requires authentication)
+///   POST /api/v1/admin/products/{id}/prices  (requires catalogo:productos:gestionar)
+/// DB: SIGCM2_Test_Api (ApiIntegration collection — shared TestWebAppFactory).
+///
+/// Each test creates its own product (via SQL) to avoid inter-test dependencies.
+/// </summary>
+[Collection("ApiIntegration")]
+public sealed class ProductPricesControllerTests : IAsyncLifetime
+{
+    private const string ConnectionString = TestConnectionStrings.ApiTestDb;
+
+    private readonly TestWebAppFactory _factory;
+    private readonly HttpClient _client;
+
+    // Seeded once per class — valid MedioId and ProductTypeId from canonical data
+    private int _medioId;
+    private int _productTypeId;
+
+    public ProductPricesControllerTests(TestWebAppFactory factory)
+    {
+        _factory = factory;
+        _client = factory.CreateClient();
+    }
+
+    // ── Lifecycle ─────────────────────────────────────────────────────────────
+
+    public async Task InitializeAsync()
+    {
+        await using var conn = new SqlConnection(ConnectionString);
+        await conn.OpenAsync();
+
+        // Resolve a valid MedioId (dbo.Medio uses 'Activo' column)
+        _medioId = await conn.QuerySingleAsync<int>(
+            "SELECT TOP 1 Id FROM dbo.Medio WHERE Activo = 1 ORDER BY Id");
+
+        // Resolve or seed a valid ProductTypeId (dbo.ProductType uses 'IsActive' column)
+        var ptId = await conn.QuerySingleOrDefaultAsync<int?>(
+            "SELECT TOP 1 Id FROM dbo.ProductType WHERE IsActive = 1 ORDER BY Id");
+        if (ptId is null)
+        {
+            ptId = await conn.QuerySingleAsync<int>("""
+                INSERT INTO dbo.ProductType (Nombre, HasDuration, RequiresText, RequiresCategory, IsBundle, AllowImages, IsActive, FechaCreacion)
+                VALUES ('PT_Prices_Test', 0, 0, 0, 0, 0, 1, SYSUTCDATETIME());
+                SELECT CAST(SCOPE_IDENTITY() AS INT);
+                """);
+        }
+        _productTypeId = ptId.Value;
+    }
+
+    public Task DisposeAsync() => Task.CompletedTask;
+
+    // ── Auth helpers ──────────────────────────────────────────────────────────
+
+    /// <summary>Generates a bearer token for admin (has catalogo:productos:gestionar via 'admin' role).</summary>
+    private string GetAdminToken()
+    {
+        var jwt = _factory.Services.GetRequiredService<IJwtService>();
+        return jwt.GenerateAccessToken(new Usuario(
+            id: 1, username: "admin", passwordHash: "x",
+            nombre: "Admin", apellido: "Sys", email: null,
+            rol: "admin", permisosJson: """{"grant":[],"deny":[]}""", activo: true));
+    }
+
+    /// <summary>Generates a bearer token for cajero (does NOT have catalogo:productos:gestionar).</summary>
+    private string GetCajeroToken()
+    {
+        var jwt = _factory.Services.GetRequiredService<IJwtService>();
+        return jwt.GenerateAccessToken(new Usuario(
+            id: 9999, username: "cajero_test", passwordHash: "x",
+            nombre: "Cajero", apellido: "Test", email: null,
+            rol: "cajero", permisosJson: """{"grant":[],"deny":[]}""", activo: true));
+    }
+
+    private HttpRequestMessage BuildRequest(
+        HttpMethod method, string url, object? body = null, string? token = null)
+    {
+        var req = new HttpRequestMessage(method, url);
+        if (token is not null)
+            req.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
+        if (body is not null)
+            req.Content = JsonContent.Create(body);
+        return req;
+    }
+
+    // ── DB seed helpers ───────────────────────────────────────────────────────
+
+    /// <summary>Seeds a unique product and returns its Id.</summary>
+    private async Task<int> SeedProductAsync(bool activo = true)
+    {
+        await using var conn = new SqlConnection(ConnectionString);
+        await conn.OpenAsync();
+        var nombre = $"PP_{Guid.NewGuid():N}"[..35];
+        // dbo.Product uses 'IsActive' column (PRD-002 convention)
+        return await conn.QuerySingleAsync<int>("""
+            INSERT INTO dbo.Product (Nombre, MedioId, ProductTypeId, BasePrice, PriceDurationDays, IsActive, FechaCreacion)
+            VALUES (@Nombre, @MedioId, @PtId, 100.00, NULL, @IsActive, SYSUTCDATETIME());
+            SELECT CAST(SCOPE_IDENTITY() AS INT);
+            """,
+            new { Nombre = nombre, MedioId = _medioId, PtId = _productTypeId, IsActive = activo ? 1 : 0 });
+    }
+
+    /// <summary>
+    /// Inserts a ProductPrice row directly (bypasses SP forward-only guard) to set up test scenarios.
+    /// </summary>
+    private async Task<long> SeedPriceDirectAsync(
+        int productId, decimal price, DateOnly pvf, DateOnly? pvt)
+    {
+        await using var conn = new SqlConnection(ConnectionString);
+        await conn.OpenAsync();
+        return await conn.QuerySingleAsync<long>("""
+            INSERT INTO dbo.ProductPrices (ProductId, Price, PriceValidFrom, PriceValidTo, FechaCreacion)
+            VALUES (@ProductId, @Price, @PriceValidFrom, @PriceValidTo, SYSUTCDATETIME());
+            SELECT CAST(SCOPE_IDENTITY() AS BIGINT);
+            """,
+            new
+            {
+                ProductId = productId,
+                Price = price,
+                PriceValidFrom = pvf.ToDateTime(TimeOnly.MinValue),
+                PriceValidTo = pvt.HasValue ? (DateTime?)pvt.Value.ToDateTime(TimeOnly.MinValue) : null
+            });
+    }
+
+    // ── GET /api/v1/products/{id}/prices ─────────────────────────────────────
+
+    [Fact]
+    public async Task GetPrices_WithoutAuth_Returns401()
+    {
+        using var req = BuildRequest(HttpMethod.Get, "/api/v1/products/1/prices");
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.Unauthorized);
+    }
+
+    [Fact]
+    public async Task GetPrices_EmptyHistory_Returns200WithEmptyArray()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+
+        using var req = BuildRequest(HttpMethod.Get, $"/api/v1/products/{productId}/prices", token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.OK);
+        var json = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        json.ValueKind.Should().Be(JsonValueKind.Array);
+        json.GetArrayLength().Should().Be(0);
+    }
+
+    [Fact]
+    public async Task GetPrices_WithHistory_Returns200OrderedDescending()
+    {
+        var productId = await SeedProductAsync();
+
+        // Seed 3 prices: 2 closed + 1 active (in ascending order to verify API returns DESC)
+        await SeedPriceDirectAsync(productId, 50m,  new DateOnly(2026, 1, 1), new DateOnly(2026, 1, 31));
+        await SeedPriceDirectAsync(productId, 75m,  new DateOnly(2026, 2, 1), new DateOnly(2026, 2, 28));
+        await SeedPriceDirectAsync(productId, 100m, new DateOnly(2026, 3, 1), null);
+
+        var token = GetAdminToken();
+        using var req = BuildRequest(HttpMethod.Get, $"/api/v1/products/{productId}/prices", token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.OK);
+        var items = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        items.GetArrayLength().Should().Be(3);
+
+        // First item = most recent (active, March)
+        var first = items[0];
+        first.GetProperty("priceValidFrom").GetString().Should().Be("2026-03-01");
+        first.GetProperty("isActive").GetBoolean().Should().BeTrue();
+        first.GetProperty("priceValidTo").ValueKind.Should().Be(JsonValueKind.Null);
+
+        // Last item = oldest (January)
+        var last = items[2];
+        last.GetProperty("priceValidFrom").GetString().Should().Be("2026-01-01");
+        last.GetProperty("isActive").GetBoolean().Should().BeFalse();
+        last.GetProperty("priceValidTo").GetString().Should().Be("2026-01-31");
+    }
+
+    [Fact]
+    public async Task GetPrices_ProductNotFound_Returns404()
+    {
+        var token = GetAdminToken();
+        using var req = BuildRequest(HttpMethod.Get, "/api/v1/products/999999999/prices", token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.NotFound);
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        body.GetProperty("error").GetString().Should().Be("product_not_found");
+    }
+
+    // ── POST /api/v1/admin/products/{id}/prices ───────────────────────────────
+
+    [Fact]
+    public async Task PostPrice_WithoutAuth_Returns401()
+    {
+        using var req = BuildRequest(HttpMethod.Post, "/api/v1/admin/products/1/prices",
+            body: new { price = 200m, priceValidFrom = "2026-05-01" });
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.Unauthorized);
+    }
+
+    [Fact]
+    public async Task PostPrice_WithoutPermission_Returns403()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetCajeroToken();
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 200m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.Forbidden);
+    }
+
+    [Fact]
+    public async Task PostPrice_FirstPrice_Returns201WithClosedNull()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+        // Use tomorrow to ensure >= hoy_AR passes FluentValidation
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 250m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.Created);
+
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        body.TryGetProperty("created", out var created).Should().BeTrue();
+        body.TryGetProperty("closed", out var closed).Should().BeTrue();
+
+        created.GetProperty("price").GetDecimal().Should().Be(250m);
+        created.GetProperty("priceValidFrom").GetString().Should().Be(pvf);
+        created.GetProperty("isActive").GetBoolean().Should().BeTrue();
+        closed.ValueKind.Should().Be(JsonValueKind.Null);
+
+        // Location header must be present
+        resp.Headers.Location.Should().NotBeNull();
+    }
+
+    [Fact]
+    public async Task PostPrice_SecondPrice_Returns201WithClosedNotNull()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+
+        // Seed an existing active price at a past date (direct insert bypasses SP)
+        await SeedPriceDirectAsync(productId, 100m, new DateOnly(2026, 4, 1), null);
+
+        // New price must be strictly greater than active PVF
+        var newPvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(2).ToString("yyyy-MM-dd");
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 300m, priceValidFrom = newPvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.Created);
+
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        var closed = body.GetProperty("closed");
+        closed.ValueKind.Should().NotBe(JsonValueKind.Null);
+        closed.GetProperty("price").GetDecimal().Should().Be(100m);
+
+        // PriceValidTo of closed = newPvf - 1 day
+        var expectedPvt = DateOnly.ParseExact(newPvf, "yyyy-MM-dd").AddDays(-1).ToString("yyyy-MM-dd");
+        closed.GetProperty("priceValidTo").GetString().Should().Be(expectedPvt);
+
+        var created = body.GetProperty("created");
+        created.GetProperty("price").GetDecimal().Should().Be(300m);
+        created.GetProperty("priceValidFrom").GetString().Should().Be(newPvf);
+        created.GetProperty("isActive").GetBoolean().Should().BeTrue();
+    }
+
+    [Fact]
+    public async Task PostPrice_PriceZero_Returns400()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 0m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task PostPrice_NegativePrice_Returns400()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = -5m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task PostPrice_PastDate_Returns400()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+        // Clearly in the past
+        const string pastDate = "2020-01-01";
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 100m, priceValidFrom = pastDate },
+            token: token);
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.BadRequest);
+    }
+
+    [Fact]
+    public async Task PostPrice_ProductNotFound_Returns404()
+    {
+        var token = GetAdminToken();
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, "/api/v1/admin/products/999999999/prices",
+            body: new { price = 100m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.NotFound);
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        body.GetProperty("error").GetString().Should().Be("product_not_found");
+    }
+
+    [Fact]
+    public async Task PostPrice_ForwardOnlyViolation_Returns409()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+
+        // Seed active price at a far-future date
+        await SeedPriceDirectAsync(productId, 200m, new DateOnly(2099, 12, 1), null);
+
+        // Try to add price with a date BEFORE the active one
+        const string retroPvf = "2099-11-01";
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 150m, priceValidFrom = retroPvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.Conflict);
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        body.GetProperty("error").GetString().Should().Be("product_price_forward_only");
+    }
+
+    [Fact]
+    public async Task PostPrice_SamePvfAsActive_Returns409()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+
+        // Seed active price at a far-future date
+        await SeedPriceDirectAsync(productId, 200m, new DateOnly(2099, 12, 1), null);
+
+        // Try to add price with the SAME date — also rejected (forward-only: must be strictly greater)
+        const string samePvf = "2099-12-01";
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 250m, priceValidFrom = samePvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+
+        resp.StatusCode.Should().Be(HttpStatusCode.Conflict);
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        body.GetProperty("error").GetString().Should().Be("product_price_forward_only");
+    }
+
+    // ── Audit Event ───────────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task PostPrice_Success_CreatesAuditEvent()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 500m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.Created);
+
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        var newId = body.GetProperty("created").GetProperty("id").GetInt64();
+
+        // Verify audit event row in SIGCM2_Test_Api
+        await using var conn = new SqlConnection(ConnectionString);
+        await conn.OpenAsync();
+        var auditCount = await conn.QuerySingleAsync<int>("""
+            SELECT COUNT(1) FROM dbo.AuditEvent
+            WHERE Action = 'product_price.created'
+              AND TargetType = 'ProductPrice'
+              AND TargetId = @TargetId
+            """, new { TargetId = newId.ToString() });
+
+        auditCount.Should().Be(1, because: "IAuditLogger must record product_price.created after a successful POST");
+    }
+
+    // ── DateOnly JSON format ──────────────────────────────────────────────────
+
+    [Fact]
+    public async Task PostPrice_DateOnly_SerializesAsYyyyMmDd()
+    {
+        var productId = await SeedProductAsync();
+        var token = GetAdminToken();
+        var pvf = DateOnly.FromDateTime(DateTime.UtcNow).AddDays(1).ToString("yyyy-MM-dd");
+
+        using var req = BuildRequest(HttpMethod.Post, $"/api/v1/admin/products/{productId}/prices",
+            body: new { price = 999m, priceValidFrom = pvf },
+            token: token);
+        var resp = await _client.SendAsync(req);
+        resp.StatusCode.Should().Be(HttpStatusCode.Created);
+
+        var body = await resp.Content.ReadFromJsonAsync<JsonElement>();
+        var returnedPvf = body.GetProperty("created").GetProperty("priceValidFrom").GetString();
+
+        // DateOnlyJsonConverter must produce "yyyy-MM-dd" — no time, no TZ suffix
+        returnedPvf.Should().MatchRegex(@"^\d{4}-\d{2}-\d{2}$",
+            because: "DateOnlyJsonConverter (UDT-011) must serialize DateOnly as yyyy-MM-dd");
+        returnedPvf.Should().Be(pvf);
+    }
+}