diff --git a/OpenNest.Api/NestRequestPlate.cs b/OpenNest.Api/NestRequestPlate.cs
index 6999ad3..31de3e9 100644
--- a/OpenNest.Api/NestRequestPlate.cs
+++ b/OpenNest.Api/NestRequestPlate.cs
@@ -5,6 +5,9 @@ namespace OpenNest.Api;
 /// <summary>One explicit physical-stock type for a whole nesting job.</summary>
 public class NestRequestPlate
 {
+    /// <summary>Positive per-sheet cost in common units; omit on every row for area scoring.</summary>
+    public double? Cost { get; init; }
+
     public string Id { get; init; }
     public Size Size { get; init; }
 
diff --git a/OpenNest.Api/NestResponse.cs b/OpenNest.Api/NestResponse.cs
index 6cbd21a..85af3f0 100644
--- a/OpenNest.Api/NestResponse.cs
+++ b/OpenNest.Api/NestResponse.cs
@@ -44,6 +44,7 @@ public class NestResponse
     public IReadOnlyList<NestPartFulfillment> Fulfillment { get; init; } = [];
     public IReadOnlyList<NestStockUsage> StockUsage { get; init; } = [];
     public IReadOnlyList<NestPlateStockMapping> PlateStockMappings { get; init; } = [];
+    public NestCostSummary Costs { get; init; }
     public Nest Nest { get; init; }
     public NestRequest Request { get; init; }
 
@@ -86,6 +87,7 @@ public class NestResponse
                     Fulfillment = Fulfillment is null
                         ? []
                         : new List<NestPartFulfillment>(Fulfillment),
+                    Costs = Costs,
                     StockUsage = StockUsage is null ? [] : new List<NestStockUsage>(StockUsage),
                     PlateStockMappings = PlateStockMappings is null
                         ? []
@@ -171,6 +173,7 @@ public class NestResponse
             Fulfillment = hasStatusMetadata ? archive.Fulfillment ?? [] : [],
             StockUsage = hasStatusMetadata ? archive.StockUsage ?? [] : [],
             PlateStockMappings = hasStatusMetadata ? archive.PlateStockMappings ?? [] : [],
+            Costs = archive.Costs,
             Nest = nest,
             Request = request,
         };
@@ -178,6 +181,7 @@ public class NestResponse
 
     private sealed class NestResponseArchiveDto
     {
+        public NestCostSummary Costs { get; init; }
         public int SchemaVersion { get; init; }
         public int SheetCount { get; init; }
         public double Utilization { get; init; }
diff --git a/OpenNest.Api/NestRunner.cs b/OpenNest.Api/NestRunner.cs
index f30e9a5..5e9d265 100644
--- a/OpenNest.Api/NestRunner.cs
+++ b/OpenNest.Api/NestRunner.cs
@@ -28,6 +28,7 @@ public static class NestRunner
         if (requestParts.Count == 0)
             throw new ArgumentException("Request must contain at least one part.", nameof(request));
 
+        var stock = CreateStock(request);
         var sw = Stopwatch.StartNew();
         var parts = IdentifyParts(requestParts);
         var importedByPath = new Dictionary<string, Drawing>(StringComparer.Ordinal);
@@ -82,7 +83,6 @@ public static class NestRunner
             });
         }
 
-        var stock = CreateStock(request);
         var engineName = request.Engine ?? ResolvePlacementStrategy(request);
         var jobProgress = progress == null ? null : new JobProgressBridge(progress);
         var result = NestPipeline.Run(new NestPipelineRequest(
@@ -91,6 +91,9 @@ public static class NestRunner
         // API returns a detached proposal, not an acceptance/commit to a caller's nest.
         // Invalid but representable proposals retain every pose and carry explicit validation status.
         var nest = new Nest { Thickness = request.Thickness, Material = new Material(request.Material) };
+        if (request.Plates != null)
+            nest.PlateOptions = stock.Where(s => s.Quantity != 0).Select(s => new PlateOption
+            { Width = s.Size.Width, Length = s.Size.Length, Cost = s.Cost ?? 0 }).ToList();
         foreach (var item in items)
             nest.Drawings.Add(item.Drawing);
         foreach (var proposed in result.Plates)
@@ -144,6 +147,7 @@ public static class NestRunner
                 Violations = result.Violations,
                 Fulfillment = fulfillment,
                 StockUsage = usage,
+                Costs = result.CanKeep && result.IsValid ? NestCostSummary.FromAccepted(result) : null,
                 PlateStockMappings = result.Plates.Select((value, index) =>
                     new NestPlateStockMapping(index, value.Stock.Id)).ToArray(),
                 Nest = nest,
@@ -209,11 +213,13 @@ public static class NestRunner
                     plate.Quantity,
                     plate.PartSpacing,
                     plate.EdgeSpacing,
-                    plate.Quadrant
+                    plate.Quadrant,
+                    plate.Cost
                 )
             );
         }
 
+        NestJobValidator.ValidateStockCosts(stock);
         return stock;
     }
 
diff --git a/OpenNest.Tests/Api/NestRunnerTests.cs b/OpenNest.Tests/Api/NestRunnerTests.cs
index 9076b06..881decd 100644
--- a/OpenNest.Tests/Api/NestRunnerTests.cs
+++ b/OpenNest.Tests/Api/NestRunnerTests.cs
@@ -4,14 +4,59 @@ using System.Linq;
 using System.Threading.Tasks;
 using OpenNest.Api;
 using OpenNest.Converters;
+using OpenNest.Engine.Jobs;
 using OpenNest.Geometry;
 using OpenNest.IO;
-using OpenNest.Engine.Jobs;
 
 namespace OpenNest.Tests.Api;
 
 public class NestRunnerTests
 {
+    [Fact]
+    public async Task ExplicitPricesSelectCheaperStockAndSurviveArchive()
+    {
+        var path = CreateTempSquareDxf(4, 4);
+        var archive = Path.ChangeExtension(path, ".nestquote");
+        try
+        {
+            var response = await NestRunner.RunAsync(new NestRequest
+            {
+                Engine = "Rectangles",
+                Parts = [new NestRequestPart { DxfPath = path, Quantity = 1 }],
+                Plates = [new NestRequestPlate { Id = "small", Size = new Size(10, 10), Quantity = 1, Cost = 50 },
+                    new NestRequestPlate { Id = "large", Size = new Size(12, 12), Quantity = 1, Cost = 7 }],
+            });
+            Assert.Equal(NestValidationStatus.Valid, response.ValidationStatus);
+            Assert.Equal("large", Assert.Single(response.PlateStockMappings).StockId);
+            Assert.Equal("supplied-cost", response.Costs.Basis);
+            Assert.Equal(7, response.Costs.GrossTotal);
+            Assert.Equal(7, response.Costs.NetScore);
+            Assert.Equal(0, response.Costs.SalvageCredit);
+            await response.SaveAsync(archive);
+            var reopened = await NestResponse.LoadAsync(archive);
+            Assert.Equal(7, reopened.Costs.GrossTotal);
+            Assert.Equal(new[] { 50d, 7d }, reopened.Nest.PlateOptions.Select(p => p.Cost));
+            Assert.Equal(7, reopened.Request.Plates[1].Cost);
+        }
+        finally
+        {
+            File.Delete(path);
+            File.Delete(archive);
+        }
+    }
+
+    [Fact]
+    public async Task MixedCostsFailBeforeImport()
+    {
+        var error = await Assert.ThrowsAsync<ArgumentException>(() => NestRunner.RunAsync(new NestRequest
+        {
+            Parts = [new NestRequestPart { DxfPath = "missing.dxf", Quantity = 1 }],
+            Plates = [new NestRequestPlate { Id = "priced", Size = new Size(10, 10), Cost = 2 },
+                new NestRequestPlate { Id = "missing", Size = new Size(12, 12) }],
+        }));
+        Assert.Contains("Missing: missing", error.Message);
+    }
+
     [Fact]
     public async Task RunAsync_LegacySheetSize_UsesUnlimitedLegacyStockAndDerivedPartId()
     {
diff --git a/docs/automatic-nesting.md b/docs/automatic-nesting.md
index c25db52..dd69713 100644
--- a/docs/automatic-nesting.md
+++ b/docs/automatic-nesting.md
@@ -98,3 +98,20 @@ Response archive schema 3 persists validation status and violations. Older archi
 ## Verification
 
 `dotnet test OpenNest.FrontEnd.Tests/OpenNest.FrontEnd.Tests.csproj` exercises Console, MCP and API rejection/override, cancellation, physical-sheet settings, response IDs and archive round-trips. Its current target matches MCP's `net8.0-windows` marker but does not use WindowsDesktop and executes on Linux as well as Windows. It is included in the solution and Windows test workflow. Desktop interaction tests remain in Windows-only `OpenNest.WinForms.Tests`.
+
+## Stock costs
+
+API `NestRequestPlate.Cost` is an optional per-physical-sheet cost in caller-consistent
+units. Omit every cost for area scoring, or supply strictly positive finite costs
+for every available row. Explicit zero and mixed priced/unpriced available stock
+are rejected before import. Quantity-zero rows do not select the cost mode.
+
+Validated proposals expose `Costs` (`Basis`, `Stock`, `GrossTotal`, `SalvageCredit`,
+`NetScore`) and persist them in quote archives. `area` identifies fallback scoring;
+`supplied-cost` identifies explicit prices. API salvage is disabled, so two sheets
+costing 25 each report gross and net totals of 50 with zero salvage credit. Totals
+exclude penalties for unplaced demand. Invalid proposals have no cost summary;
+overflow fails instead of becoming a score.
+
+Returned nests preserve offered stock prices. These are cost-aware heuristics,
+not global cost optimizers; validation and fulfillment remain required.
diff --git a/docs/nest-file-format.md b/docs/nest-file-format.md
index 483ed31..45c6f71 100644
--- a/docs/nest-file-format.md
+++ b/docs/nest-file-format.md
@@ -91,3 +91,8 @@ The existing `plateOptions` entries retain width, length and `cost`; no new `.ne
 format version is required. Legacy zero cost means unspecified, not a free sheet.
 Positive costs are generic per-sheet values in caller-consistent units. Solving
 requires all available options to be priced or all to be unspecified.
+
+API returned nests retain offered options, excluding rows with zero available
+quantity because `.nest` options do not retain inventory. Options are offers, not
+a per-sheet purchase ledger. API quote archives additionally retain request costs
+and validated proposal cost summaries; old archives load with `Costs == null`.