fix: show cutting parameters dialog before assigning lead-ins

Auto-assign lead-ins silently reused existing plate parameters with no
way to change them after the first assignment. Now a dialog with the
full CuttingPanel is shown every time, pre-populated with the current
settings, so the user can review and modify before confirming.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

OpenNest/Forms/CuttingParametersDialog.cs

@@ -0,0 +1,68 @@
+using OpenNest.CNC.CuttingStrategy;
+using OpenNest.Controls;
+using System.Drawing;
+using System.Windows.Forms;
+
+namespace OpenNest.Forms
+{
+    public class CuttingParametersDialog : Form
+    {
+        private readonly CuttingPanel cuttingPanel;
+
+        public CuttingParametersDialog()
+        {
+            Text = "Cutting Parameters";
+            Size = new Size(400, 560);
+            FormBorderStyle = FormBorderStyle.FixedDialog;
+            MaximizeBox = false;
+            MinimizeBox = false;
+            StartPosition = FormStartPosition.CenterParent;
+
+            cuttingPanel = new CuttingPanel
+            {
+                Dock = DockStyle.Fill
+            };
+
+            var buttonPanel = new Panel
+            {
+                Dock = DockStyle.Bottom,
+                Height = 40
+            };
+
+            var btnOk = new Button
+            {
+                Text = "OK",
+                DialogResult = DialogResult.OK,
+                Size = new Size(80, 28),
+                Location = new Point(220, 6)
+            };
+
+            var btnCancel = new Button
+            {
+                Text = "Cancel",
+                DialogResult = DialogResult.Cancel,
+                Size = new Size(80, 28),
+                Location = new Point(305, 6)
+            };
+
+            buttonPanel.Controls.Add(btnOk);
+            buttonPanel.Controls.Add(btnCancel);
+
+            Controls.Add(cuttingPanel);
+            Controls.Add(buttonPanel);
+
+            AcceptButton = btnOk;
+            CancelButton = btnCancel;
+        }
+
+        public void LoadParameters(CuttingParameters parameters)
+        {
+            cuttingPanel.LoadFromParameters(parameters);
+        }
+
+        public CuttingParameters GetParameters()
+        {
+            return cuttingPanel.BuildParameters();
+        }
+    }
+}

OpenNest/Forms/EditNestForm.cs

@@ -719,19 +719,17 @@ namespace OpenNest.Forms
 
             var plate = PlateView.Plate;
 
-            if (plate.CuttingParameters == null)
-            {
-                var json = Properties.Settings.Default.CuttingParametersJson;
-                if (!string.IsNullOrEmpty(json))
-                {
-                    try { plate.CuttingParameters = CuttingParametersSerializer.Deserialize(json); }
-                    catch { plate.CuttingParameters = new CuttingParameters(); }
-                }
-                else
-                {
-                    plate.CuttingParameters = new CuttingParameters();
-                }
-            }
+            var parameters = LoadOrDefaultParameters(plate.CuttingParameters);
+
+            using var dlg = new CuttingParametersDialog();
+            dlg.LoadParameters(parameters);
+
+            if (dlg.ShowDialog() != DialogResult.OK)
+                return;
+
+            parameters = dlg.GetParameters();
+            plate.CuttingParameters = parameters;
+            SaveCuttingParameters(parameters);
 
             var assigner = new LeadInAssigner
             {
@@ -782,17 +780,16 @@ namespace OpenNest.Forms
             if (Nest == null)
                 return;
 
-            CuttingParameters parameters;
-            var json = Properties.Settings.Default.CuttingParametersJson;
-            if (!string.IsNullOrEmpty(json))
-            {
-                try { parameters = CuttingParametersSerializer.Deserialize(json); }
-                catch { parameters = new CuttingParameters(); }
-            }
-            else
-            {
-                parameters = new CuttingParameters();
-            }
+            var parameters = LoadOrDefaultParameters(PlateView?.Plate?.CuttingParameters);
+
+            using var dlg = new CuttingParametersDialog();
+            dlg.LoadParameters(parameters);
+
+            if (dlg.ShowDialog() != DialogResult.OK)
+                return;
+
+            parameters = dlg.GetParameters();
+            SaveCuttingParameters(parameters);
 
             var assigner = new LeadInAssigner
             {
@@ -840,24 +837,34 @@ namespace OpenNest.Forms
 
             var plate = PlateView.Plate;
 
-            // If no cutting parameters exist, initialize from saved settings or defaults
             if (plate.CuttingParameters == null)
-            {
-                var json = Properties.Settings.Default.CuttingParametersJson;
-                if (!string.IsNullOrEmpty(json))
-                {
-                    try { plate.CuttingParameters = CuttingParametersSerializer.Deserialize(json); }
-                    catch { plate.CuttingParameters = new CuttingParameters(); }
-                }
-                else
-                {
-                    plate.CuttingParameters = new CuttingParameters();
-                }
-            }
+                plate.CuttingParameters = LoadOrDefaultParameters(null);
 
             PlateView.SetAction(typeof(Actions.ActionLeadIn));
         }
 
+        private static CuttingParameters LoadOrDefaultParameters(CuttingParameters existing)
+        {
+            if (existing != null)
+                return existing;
+
+            var json = Properties.Settings.Default.CuttingParametersJson;
+            if (!string.IsNullOrEmpty(json))
+            {
+                try { return CuttingParametersSerializer.Deserialize(json); }
+                catch { /* fall through */ }
+            }
+
+            return new CuttingParameters();
+        }
+
+        private static void SaveCuttingParameters(CuttingParameters parameters)
+        {
+            var json = CuttingParametersSerializer.Serialize(parameters);
+            Properties.Settings.Default.CuttingParametersJson = json;
+            Properties.Settings.Default.Save();
+        }
+
         private void ImportDrawings_Click(object sender, EventArgs e)
         {
             Import();