diff --git a/OpenNest.Core/Converters/DrawingMarkRecovery.cs b/OpenNest.Core/Converters/DrawingMarkRecovery.cs
index df92fc1a..bcb4c417 100644
--- a/OpenNest.Core/Converters/DrawingMarkRecovery.cs
+++ b/OpenNest.Core/Converters/DrawingMarkRecovery.cs
@@ -57,8 +57,7 @@ public static class DrawingMarkRecovery
             return false;
 
         AppendMarks(drawing.Program, marks);
-        drawing.UpdateArea();
-        drawing.RecomputeCanonicalAngle();
+        drawing.ProgramChanged();
 
         foreach (var part in placedParts.Where(part => ReferenceEquals(part.BaseDrawing, drawing)
                      && !part.HasManualLeadIns))
diff --git a/OpenNest.Core/Drawing.cs b/OpenNest.Core/Drawing.cs
index de3fee1f..5280a8d3 100644
--- a/OpenNest.Core/Drawing.cs
+++ b/OpenNest.Core/Drawing.cs
@@ -79,17 +79,24 @@ namespace OpenNest
             set
             {
                 program = value;
-                UpdateArea();
-                RecomputeCanonicalAngle();
+                ProgramChanged();
             }
         }
 
         /// <summary>
-        /// Recomputes and stores the canonical angle from the current Program.
-        /// Callers that mutate Program in place (rather than reassigning it) must invoke this explicitly.
-        /// Cut-off drawings are left with Angle=0.
+        /// Refreshes everything derived from <see cref="Program"/>: <see cref="Area"/> and the
+        /// canonical angle in <see cref="SourceInfo.Angle"/>. Assigning <see cref="Program"/>
+        /// calls it; callers that mutate the program in place (rather than reassigning it) must
+        /// call it afterwards.
         /// </summary>
-        public void RecomputeCanonicalAngle()
+        public void ProgramChanged()
+        {
+            UpdateArea();
+            RecomputeCanonicalAngle();
+        }
+
+        // Cut-off drawings are left with Angle=0.
+        private void RecomputeCanonicalAngle()
         {
             if (Source == null)
                 Source = new SourceInfo();
@@ -188,15 +195,25 @@ namespace OpenNest
 
         public double Area { get; protected set; }
 
-        public void UpdateArea()
+        private void UpdateArea()
         {
+            if (program == null)
+            {
+                Area = 0;
+                return;
+            }
+
             var geometry = ConvertProgram
-                .ToGeometry(Program)
+                .ToGeometry(program)
                 .Where(entity => SpecialLayers.IsMaterial(entity.Layer));
             var shapes = ShapeBuilder.GetShapes(geometry);
 
+            // No material left (e.g. only marks): a stale area would still count as material.
             if (shapes.Count == 0)
+            {
+                Area = 0;
                 return;
+            }
 
             var areas = new double[shapes.Count];
 
@@ -255,7 +272,7 @@ namespace OpenNest
         /// setter via <see cref="CanonicalAngle.Compute"/>. A value of 0 means the drawing is
         /// already canonical or <see cref="Drawing.IsCutOff"/> is true. Callers that mutate
         /// <see cref="Drawing.Program"/> in place must invoke
-        /// <see cref="Drawing.RecomputeCanonicalAngle"/> to refresh.
+        /// <see cref="Drawing.ProgramChanged"/> to refresh.
         /// </summary>
         public double Angle { get; set; }
     }
diff --git a/OpenNest.IO/NestReader.cs b/OpenNest.IO/NestReader.cs
index e9d25b6d..e2710b7f 100644
--- a/OpenNest.IO/NestReader.cs
+++ b/OpenNest.IO/NestReader.cs
@@ -336,8 +336,7 @@ namespace OpenNest.IO
                         && ScribeLayerRepair.Apply(drawing.Program, marks, drawing.Source.Offset) > 0
                     )
                     {
-                        drawing.UpdateArea();
-                        drawing.RecomputeCanonicalAngle();
+                        drawing.ProgramChanged();
                     }
                 }
 
diff --git a/OpenNest.Tests/BestFit/BestFitCacheStoreTests.cs b/OpenNest.Tests/BestFit/BestFitCacheStoreTests.cs
index f3ce506a..f853f9f8 100644
--- a/OpenNest.Tests/BestFit/BestFitCacheStoreTests.cs
+++ b/OpenNest.Tests/BestFit/BestFitCacheStoreTests.cs
@@ -194,7 +194,7 @@ public class BestFitCacheStoreTests
     {
         var drawing = MakeDrawing();
         drawing.Program.Rotate(0.5, drawing.Program.BoundingBox().Center);
-        drawing.RecomputeCanonicalAngle();
+        drawing.ProgramChanged();
         Assert.NotEqual(0.0, drawing.Source.Angle);
         return drawing;
     }
diff --git a/OpenNest.Tests/BestFit/BestFitCacheTests.cs b/OpenNest.Tests/BestFit/BestFitCacheTests.cs
index 8c8bc585..3c6c92c2 100644
--- a/OpenNest.Tests/BestFit/BestFitCacheTests.cs
+++ b/OpenNest.Tests/BestFit/BestFitCacheTests.cs
@@ -22,7 +22,7 @@ public class BestFitCacheTests
     {
         var drawing = new TShape { Width = 10, Height = 8 }.GetDrawing();
         drawing.Program.Rotate(Angle.ToRadians(30), drawing.Program.BoundingBox().Center);
-        drawing.RecomputeCanonicalAngle();
+        drawing.ProgramChanged();
         return drawing;
     }
 
diff --git a/OpenNest.Tests/BestFit/BestFitResultFrameTests.cs b/OpenNest.Tests/BestFit/BestFitResultFrameTests.cs
index c791c1a5..8871deff 100644
--- a/OpenNest.Tests/BestFit/BestFitResultFrameTests.cs
+++ b/OpenNest.Tests/BestFit/BestFitResultFrameTests.cs
@@ -35,7 +35,7 @@ public class BestFitResultFrameTests
     {
         var drawing = new TShape { Width = 10, Height = 8 }.GetDrawing();
         drawing.Program.Rotate(Angle.ToRadians(30), drawing.Program.BoundingBox().Center);
-        drawing.RecomputeCanonicalAngle();
+        drawing.ProgramChanged();
 
         var canonical = CanonicalFrame.AsCanonicalCopy(drawing);
         var result = EvaluateOffsetPair(canonical, new Vector(40, 30));
diff --git a/OpenNest.Tests/DrawingProgramChangedTests.cs b/OpenNest.Tests/DrawingProgramChangedTests.cs
new file mode 100644
index 00000000..4c5836d0
--- /dev/null
+++ b/OpenNest.Tests/DrawingProgramChangedTests.cs
@@ -0,0 +1,88 @@
+using System.Linq;
+using OpenNest.CNC;
+using OpenNest.Geometry;
+
+namespace OpenNest.Tests;
+
+public class DrawingProgramChangedTests
+{
+    private static Program Rectangle(double width, double height)
+    {
+        var program = new Program();
+        program.Codes.Add(new RapidMove(new Vector(0, 0)));
+        program.Codes.Add(new LinearMove(new Vector(width, 0)));
+        program.Codes.Add(new LinearMove(new Vector(width, height)));
+        program.Codes.Add(new LinearMove(new Vector(0, height)));
+        program.Codes.Add(new LinearMove(new Vector(0, 0)));
+        return program;
+    }
+
+    [Fact]
+    public void InPlaceEditIsStaleUntilProgramChangedRefreshesAreaAndAngle()
+    {
+        var drawing = new Drawing("r", Rectangle(100, 50));
+        Assert.Equal(5000, drawing.Area, 6);
+        Assert.Equal(0.0, drawing.Source.Angle, 6);
+
+        // Neither edit goes through the Program setter.
+        foreach (var move in drawing.Program.Codes.OfType<LinearMove>())
+            move.EndPoint = new Vector(move.EndPoint.X * 2, move.EndPoint.Y);
+        drawing.Program.Rotate(0.5, drawing.Program.BoundingBox().Center);
+        Assert.Equal(5000, drawing.Area, 6);
+        Assert.Equal(0.0, drawing.Source.Angle, 6);
+
+        drawing.ProgramChanged();
+
+        Assert.Equal(10000, drawing.Area, 6);
+        Assert.InRange(drawing.Source.Angle, -0.52, -0.48);
+    }
+
+    [Fact]
+    public void ClearingTheMaterialZeroesTheArea()
+    {
+        var drawing = new Drawing("r", Rectangle(100, 50));
+
+        foreach (var move in drawing.Program.Codes.OfType<LinearMove>())
+            move.Layer = LayerType.Scribe;
+        drawing.ProgramChanged();
+
+        Assert.Equal(0.0, drawing.Area);
+    }
+
+    [Fact]
+    public void AnEmptiedProgramZeroesTheArea()
+    {
+        var drawing = new Drawing("r", Rectangle(100, 50));
+
+        drawing.Program.Codes.Clear();
+        drawing.ProgramChanged();
+
+        Assert.Equal(0.0, drawing.Area);
+    }
+
+    [Fact]
+    public void ANullProgramZeroesAreaAndAngle()
+    {
+        var program = Rectangle(100, 50);
+        program.Rotate(0.5, program.BoundingBox().Center);
+        var drawing = new Drawing("r", program);
+        Assert.NotEqual(0.0, drawing.Source.Angle);
+
+        drawing.Program = null;
+
+        Assert.Equal(0.0, drawing.Area);
+        Assert.Equal(0.0, drawing.Source.Angle);
+    }
+
+    [Fact]
+    public void ACutOffDrawingKeepsAngleZero()
+    {
+        var drawing = new Drawing("cut", Rectangle(100, 50)) { IsCutOff = true };
+
+        drawing.Program.Rotate(0.5, drawing.Program.BoundingBox().Center);
+        drawing.ProgramChanged();
+
+        Assert.Equal(0.0, drawing.Source.Angle);
+        Assert.Equal(5000, drawing.Area, 6);
+    }
+}
diff --git a/OpenNest.Tests/Engine/CanonicalAngleTests.cs b/OpenNest.Tests/Engine/CanonicalAngleTests.cs
index 3d872f42..b834fb48 100644
--- a/OpenNest.Tests/Engine/CanonicalAngleTests.cs
+++ b/OpenNest.Tests/Engine/CanonicalAngleTests.cs
@@ -185,7 +185,7 @@ public class DrawingCanonicalAngleWiringTests
     }
 
     [Fact]
-    public void RecomputeCanonicalAngle_UpdatesAfterMutation()
+    public void ProgramChanged_UpdatesAngleAfterMutation()
     {
         var d = new Drawing("r", RotatedRectProgram(100, 50, 0.0));
         Assert.Equal(0.0, d.Source.Angle, precision: 6);
@@ -194,7 +194,7 @@ public class DrawingCanonicalAngleWiringTests
         d.Program.Rotate(0.5, d.Program.BoundingBox().Center);
         Assert.Equal(0.0, d.Source.Angle, precision: 6); // still stale
 
-        d.RecomputeCanonicalAngle();
+        d.ProgramChanged();
         Assert.InRange(d.Source.Angle, -0.52, -0.48);
     }
 }
diff --git a/OpenNest.Tests/IO/BestFitPersistenceTests.cs b/OpenNest.Tests/IO/BestFitPersistenceTests.cs
index 3c75a80c..52813b13 100644
--- a/OpenNest.Tests/IO/BestFitPersistenceTests.cs
+++ b/OpenNest.Tests/IO/BestFitPersistenceTests.cs
@@ -237,7 +237,7 @@ public class BestFitPersistenceTests
     {
         var drawing = MakeTShape();
         drawing.Program.Rotate(Angle.ToRadians(30), drawing.Program.BoundingBox().Center);
-        drawing.RecomputeCanonicalAngle();
+        drawing.ProgramChanged();
         return drawing;
     }
 
diff --git a/OpenNest.Tests/Strategies/FillHelpersTests.cs b/OpenNest.Tests/Strategies/FillHelpersTests.cs
index e7c475fc..6cfb893d 100644
--- a/OpenNest.Tests/Strategies/FillHelpersTests.cs
+++ b/OpenNest.Tests/Strategies/FillHelpersTests.cs
@@ -34,7 +34,7 @@ public class FillHelpersTests
         {
             // Program.Rotate mutates in place; refresh the canonical angle the same way
             // a rotated CAD import carries it, or AsCanonicalCopy takes the zero-angle path.
-            drawing.RecomputeCanonicalAngle();
+            drawing.ProgramChanged();
             canonicalAngle = drawing.Source.Angle;
             Assert.False(OpenNest.Math.Tolerance.IsEqualTo(canonicalAngle, 0));
             drawing = CanonicalFrame.AsCanonicalCopy(drawing);
diff --git a/OpenNest.Training/Program.cs b/OpenNest.Training/Program.cs
index 6345a830..2e93dae8 100644
--- a/OpenNest.Training/Program.cs
+++ b/OpenNest.Training/Program.cs
@@ -167,7 +167,6 @@ int RunDataCollection(string dir, string dbPath, string saveDir, double s, strin
                 continue;
             }
 
-            drawing.UpdateArea();
             drawing.Color = PartColors[colorIndex % PartColors.Length];
             colorIndex++;
 
diff --git a/OpenNest.Training/TrainingDatabase.cs b/OpenNest.Training/TrainingDatabase.cs
index a8b7accf..3bd56adf 100644
--- a/OpenNest.Training/TrainingDatabase.cs
+++ b/OpenNest.Training/TrainingDatabase.cs
@@ -4,10 +4,10 @@ using System.IO;
 using System.Linq;
 using System.Text;
 using Microsoft.EntityFrameworkCore;
+using OpenNest.Engine;
 using OpenNest.Engine.ML;
 using OpenNest.IO;
 using OpenNest.Training.Data;
-using OpenNest.Engine;
 
 namespace OpenNest.Training
 {
@@ -137,7 +137,6 @@ namespace OpenNest.Training
                     var program = programReader.Read();
 
                     var drawing = new Drawing("backfill") { Program = program };
-                    drawing.UpdateArea();
 
                     var features = FeatureExtractor.Extract(drawing);
                     if (features == null)
@@ -175,7 +174,7 @@ namespace OpenNest.Training
             {
                 try
                 {
-                    _db.Database.ExecuteSqlRaw($"ALTER TABLE Runs ADD COLUMN {name} {type}");
+                    _db.Database.ExecuteSql($"ALTER TABLE Runs ADD COLUMN {name} {type}");
                 }
                 catch
                 {