feat(ui): validate Auto Nest stock prices and report costs

OpenNest.WinForms.Tests/Forms/AutoNestFormStockOptionsTests.cs

@@ -10,6 +10,64 @@ namespace OpenNest.WinForms.Tests.Forms;
 
 public class AutoNestFormStockOptionsTests
 {
+    [Theory]
+    [InlineData("invalid", false)]
+    [InlineData("-1", false)]
+    [InlineData("NaN", false)]
+    [InlineData("27", true)]
+    public void PendingCostEditsAreValidatedBeforePublishing(string text, bool valid)
+    {
+        RunSta(() =>
+        {
+            using var form = new AutoNestForm(new Nest());
+            form.LoadPlateOptions(new List<PlateOption> { new() { Width = 48, Length = 96, Cost = 5 } }, 0.5);
+            var grid = GetGrid(form);
+            ((TabControl)form.Controls.Find("tabControl", true).Single()).SelectedIndex = 1;
+            form.Show();
+            grid.Focus();
+            grid.CurrentCell = grid.Rows[0].Cells[1];
+            Assert.True(grid.BeginEdit(false));
+            grid.EditingControl.Text = text;
+            Assert.Equal(valid, form.TryGetPlateOptions(out var options, out var error));
+            if (valid)
+                Assert.Equal(27, Assert.Single(options).Cost);
+            else
+            {
+                Assert.Empty(options);
+                Assert.Contains("cost", error);
+            }
+            grid.CancelEdit();
+        });
+    }
+
+    [Theory]
+    [InlineData(0, 0, true)]
+    [InlineData(5, 8, true)]
+    [InlineData(5, 0, false)]
+    [InlineData(0, 5, false)]
+    [InlineData(-1, -1, false)]
+    [InlineData(double.NaN, 5, false)]
+    [InlineData(double.PositiveInfinity, 5, false)]
+    public void CostRowsRequireConsistentFiniteValues(double first, double second, bool valid)
+    {
+        RunSta(() =>
+        {
+            using var form = new AutoNestForm(new Nest());
+            form.LoadPlateOptions(new List<PlateOption>
+            {
+                new() { Width = 48, Length = 96, Cost = first },
+                new() { Width = 60, Length = 120, Cost = second },
+            }, 0.5);
+            Assert.Equal(valid, form.TryGetPlateOptions(out var options, out var error));
+            if (!valid)
+            {
+                Assert.Empty(options);
+                Assert.Contains("cost", error);
+            }
+            AssertNewRow(GetGrid(form));
+        });
+    }
+
     [Theory]
     [InlineData(false)]
     [InlineData(true)]
@@ -62,7 +120,7 @@ public class AutoNestFormStockOptionsTests
             Assert.True(rows.AllowNew);
             var added = rows.AddNew()!;
             SetValue(added, "Size", "84 x 168");
-            SetValue(added, "Cost", 123.5);
+            SetValue(added, "Cost", loadSavedOptions ? 123.5 : 0);
             ((ICancelAddNew)rows).EndNew(rows.Count - 1);
 
             var options = form.GetPlateOptions();
@@ -70,7 +128,7 @@ public class AutoNestFormStockOptionsTests
             var option = options.Last();
             Assert.Equal(84, option.Width);
             Assert.Equal(168, option.Length);
-            Assert.Equal(123.5, option.Cost);
+            Assert.Equal(loadSavedOptions ? 123.5 : 0, option.Cost);
             AssertNewRow(grid);
         });
     }
@@ -128,6 +186,7 @@ public class AutoNestFormStockOptionsTests
         var rows = Assert.IsAssignableFrom<IBindingList>(grid.DataSource);
         var row = rows.AddNew()!;
         SetValue(row, "Size", invalid);
+        SetValue(row, "Cost", 25);
         ((ICancelAddNew)rows).EndNew(rows.Count - 1);
 
         Assert.False(form.TryGetPlateOptions(out var options, out var error));

OpenNest/Forms/AutoNestForm.cs

@@ -152,6 +152,7 @@ namespace OpenNest.Forms
                 {
                     DataPropertyName = "Cost",
                     HeaderText = "Cost",
+                    ToolTipText = "Per physical sheet, in one common unit. Use zero on every row for area scoring, or positive costs on every row. Salvage credits cost proportionally; set salvage to zero for purchase totals.",
                     Width = 70,
                     AutoSizeMode = DataGridViewAutoSizeColumnMode.None,
                 }
@@ -235,6 +236,15 @@ namespace OpenNest.Forms
                 }
             }
 
+            if (plateGrid.IsCurrentCellInEditMode && plateGrid.CurrentCell != null
+                && plateGrid.Columns[plateGrid.CurrentCell.ColumnIndex].DataPropertyName == "Cost"
+                && plateGrid.EditingControl != null
+                && !ValidCost(plateGrid.EditingControl.Text))
+            {
+                error = $"Invalid stock cost in row {plateGrid.CurrentCell.RowIndex + 1}. Enter a finite positive cost, or zero on every row.";
+                return false;
+            }
+
             bool committed;
             try
             {
@@ -269,6 +279,14 @@ namespace OpenNest.Forms
                     return false;
                 }
 
+                if (!double.IsFinite(item.Cost) || item.Cost < 0
+                    || validated.Count > 0 && (validated[0].Cost == 0) != (item.Cost == 0))
+                {
+                    error = $"Invalid stock cost in row {index + 1}. Use finite positive costs on every active row, or zero on every row.";
+                    if (index < plateGrid.Rows.Count)
+                        plateGrid.Rows[index].ErrorText = error;
+                    return false;
+                }
                 if (index < plateGrid.Rows.Count)
                     plateGrid.Rows[index].ErrorText = "";
                 validated.Add(new PlateOption { Width = width, Length = length, Cost = item.Cost });
@@ -378,8 +396,17 @@ namespace OpenNest.Forms
                 UpdateSummary();
         }
 
+        private static bool ValidCost(string text) =>
+            double.TryParse(text, out var cost) && double.IsFinite(cost) && cost >= 0;
+
         private void PlateGrid_CellValidating(object sender, DataGridViewCellValidatingEventArgs e)
         {
+            if (plateGrid.Columns[e.ColumnIndex].DataPropertyName == "Cost")
+            {
+                e.Cancel = !plateGrid.Rows[e.RowIndex].IsNewRow && !ValidCost(e.FormattedValue?.ToString());
+                plateGrid.Rows[e.RowIndex].ErrorText = e.Cancel ? "Enter a finite positive cost, or zero on every row." : "";
+                return;
+            }
             if (plateGrid.Columns[e.ColumnIndex].DataPropertyName != "Size")
                 return;
 

OpenNest/Forms/MainForm.cs

@@ -1494,6 +1494,7 @@ namespace OpenNest.Forms
                     allowInvalid = true;
                 }
 
+                var costs = result.IsValid && result.CanKeep ? NestCostSummary.FromAccepted(result) : null;
                 var applied = NestPipelineCommit.ApplyToEmptyPlates(result, target.PlateManager,
                     allowInvalid, cts.Token);
                 if (applied.Count > 0)
@@ -1509,6 +1510,9 @@ namespace OpenNest.Forms
                     target.OverlapDisplay = OverlapDisplayMode.Both;
                     await target.CheckOverlapsAsync();
                 }
+                if (costs?.Basis == "supplied-cost")
+                    MessageBox.Show(this, $"Gross sheet cost: {costs.GrossTotal:G}\nEstimated salvage credit: {costs.SalvageCredit:G}\nNet score: {costs.NetScore:G}",
+                        "Auto Nest Cost", MessageBoxButtons.OK, MessageBoxIcon.Information);
                 if (result.Status != NestJobStatus.Complete)
                     MessageBox.Show(this, $"{engineName} could not place every part ({result.StopReason}).",
                         "Auto Nest", MessageBoxButtons.OK, MessageBoxIcon.Information);

docs/automatic-nesting.md

@@ -101,29 +101,38 @@ Response archive schema 3 persists validation status and violations. Older archi
 
 ## 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.
-
+Auto Nest Stock Options accepts a generic **per physical sheet** Cost. Enter positive
+finite costs on every active row in one common unit (purchase price, area, or another
+consistent scalar). All-zero rows retain legacy area scoring: zero means unspecified,
+not free stock. Negative/nonfinite costs and mixed zero/positive rows are rejected
+before solving. The blank add row is ignored.
 
 MCP `autonest_job` accepts optional `cost` on each `sheets` row, alongside `width`,
-`length` and positive finite `quantity`. Supply positive finite costs on every row
-or omit all costs. MCP continues to reject duplicate sizes and disables salvage.
-Its result reports the cost basis, used physical counts, supplied costs, gross
-subtotals, gross total, estimated salvage credit and net score for the proposal.
+`length` and positive finite `quantity`. API `NestRequestPlate.Cost` uses the same
+nullable contract: omit every cost for area scoring, or supply strictly positive
+finite values for every available row. Explicit zero is invalid in these requests.
+Engine stock with quantity zero is unavailable and does not select the cost mode.
+MCP continues to reject duplicate sizes; API/engine stock IDs keep independent inventory.
+
+With prices, gross sheet cost is the supplied value. Salvage is still computed from
+the largest qualifying material-edge offcut; net cost is
+`Cost * (NetSheetArea / SheetArea)`. Set desktop salvage rate to zero for purchase-price
+comparisons. Entering prices preserves the selected salvage settings. MCP and API
+currently disable salvage. Without prices, scores retain their existing area units
+and tie ordering; fixed strategies retain their legacy no-salvage area tie-break.
+
+Desktop reports gross cost, estimated salvage credit and net score. MCP reports
+`basis`, each stock's used physical count, supplied cost and gross subtotal, plus
+gross total, estimated salvage credit and net score. API exposes these under `Costs`
+(`Basis`, `Stock`, `GrossTotal`, `SalvageCredit`, `NetScore`) and persists them in
+quote archives. For example, two sheets costing 25 each report gross total 50;
+with salvage disabled, credit is 0 and net score is 50. `area` identifies fallback
+scoring; `supplied-cost` identifies explicit prices. Totals cover the returned proposal,
+not previously occupied session sheets, and exclude penalties for unplaced demand.
+Invalid API proposals have no cost summary. Overflow fails instead of becoming a score.
 
 An accepted MCP solve stores requested drawing quantities and offered stock prices;
-save/reopen preserves them and existing nest metadata, plate defaults and salvage
-settings. Rejected/cancelled proposals change neither requirements nor options.
-Inventory remains request-local; saved options are offers, not a purchase ledger.
+save/reopen preserves them and existing nest metadata. Rejected/cancelled proposals
+change neither requirements nor options. Inventory remains request-local; saved
+options are offers, not a per-sheet purchase ledger. These are cost-aware heuristics,
+not global cost optimizers; validation and fulfillment remain required.