fix(cnc): show first internal rapid after cut-first programs

OpenNest.Core/CNC/RapidEnumerator.cs

@@ -31,16 +31,16 @@ namespace OpenNest.CNC
 
         private static Vector AppendProgram(Program pgm, Vector basePos, Vector startPos, List<Segment> results)
         {
-            // Draw the rapid from the previous tool position to the program's first
-            // pierce point. The walk then starts at the program origin (basePos), not
-            // the pierce: the skipped first rapid still advances pos, so starting at
-            // the pierce would apply a nonzero Incremental first delta twice (as in
-            // lead-in programs) and shift every later rapid by it.
+            // Draw the approach to the first rapid destination, or to the program
+            // origin when it starts cutting without a rapid. Only an initial rapid
+            // (or call arrival) is already represented by this approach; a later
+            // first rapid must remain visible. Walk starts at the program origin,
+            // so an incremental initial rapid is not applied twice.
             var firstPierce = FirstPiercePoint(pgm, basePos);
             results.Add(new Segment(startPos, firstPierce));
 
             var pos = basePos;
-            Walk(pgm, basePos, ref pos, skipFirst: true, results);
+            Walk(pgm, basePos, ref pos, skipFirst: StartsWithRapidOrCall(pgm), results);
             // The last rapid ends at a pierce, not necessarily the final tool position.
             return pos;
         }
@@ -53,11 +53,23 @@ namespace OpenNest.CNC
                     return FirstPiercePoint(call.Program, basePos + call.Offset);
 
                 if (pgm[i] is Motion motion)
-                    return motion.EndPoint + basePos;
+                    return motion is RapidMove ? motion.EndPoint + basePos : basePos;
             }
             return basePos;
         }
 
+        private static bool StartsWithRapidOrCall(Program pgm)
+        {
+            for (var i = 0; i < pgm.Length; i++)
+            {
+                if (pgm[i] is SubProgramCall { Program: not null })
+                    return true;
+                if (pgm[i] is Motion motion)
+                    return motion is RapidMove;
+            }
+            return false;
+        }
+
         private static void Walk(
             Program pgm,
             Vector basePos,
@@ -83,7 +95,7 @@ namespace OpenNest.CNC
                         results.Add(new Segment(pos, firstPierce));
 
                     var subPos = holeBase;
-                    Walk(program, holeBase, ref subPos, skipFirst: true, results);
+                    Walk(program, holeBase, ref subPos, skipFirst: StartsWithRapidOrCall(program), results);
                     pos = subPos;
                 }
                 else if (code is Motion motion)

OpenNest.Tests/CNC/RapidEnumeratorTests.cs

@@ -76,6 +76,70 @@ namespace OpenNest.Tests.CNC
             Assert.Equal(new Vector(108, 204), segments[1].To);
         }
 
+        [Theory]
+        [InlineData(Mode.Absolute)]
+        [InlineData(Mode.Incremental)]
+        public void Enumerate_ProgramStartingWithCut_RetainsFirstInternalRapid(Mode mode)
+        {
+            // A saved placed program can start with a lead-in cut rather than a G00.
+            // The first G00 then travels from that cutout to the next one.
+            var pgm = new Program(mode);
+            pgm.Codes.Add(new LinearMove(2, 0));
+            pgm.Codes.Add(new RapidMove(4, 1));
+            pgm.Codes.Add(new LinearMove(5, 1));
+            pgm.Codes.Add(new RapidMove(6, 2));
+
+            var segments = RapidEnumerator.Enumerate(
+                pgm,
+                basePos: new Vector(100, 200),
+                startPos: Vector.Zero
+            );
+
+            Assert.Equal(3, segments.Count);
+            Assert.Equal(new RapidEnumerator.Segment(Vector.Zero, new Vector(100, 200)), segments[0]);
+            Assert.Equal(new Vector(102, 200), segments[1].From);
+            Assert.Equal(mode == Mode.Absolute ? new Vector(104, 201) : new Vector(106, 201), segments[1].To);
+            Assert.Equal(mode == Mode.Absolute ? new Vector(105, 201) : new Vector(111, 202), segments[2].From);
+        }
+
+        [Fact]
+        public void Enumerate_EveryPartStartingWithCut_RetainsItsFirstRapid()
+        {
+            var program = new Program(Mode.Incremental);
+            program.Codes.Add(new LinearMove(1, 0));
+            program.Codes.Add(new RapidMove(1, 1));
+            program.Codes.Add(new LinearMove(0, 1));
+            var drawing = new Drawing("cut-first", program);
+            var parts = new[]
+            {
+                new Part(drawing, new Vector(10, 20)),
+                new Part(drawing, new Vector(30, 40)),
+            };
+
+            var segments = RapidEnumerator.Enumerate(parts);
+
+            Assert.Equal(4, segments.Count);
+            Assert.Equal(new RapidEnumerator.Segment(new Vector(11, 20), new Vector(12, 21)), segments[1]);
+            Assert.Equal(new RapidEnumerator.Segment(new Vector(31, 40), new Vector(32, 41)), segments[3]);
+        }
+
+        [Fact]
+        public void Enumerate_SubProgramStartingWithCut_RetainsFirstInternalRapid()
+        {
+            var hole = new Program(Mode.Incremental);
+            hole.Codes.Add(new LinearMove(1, 0));
+            hole.Codes.Add(new RapidMove(2, 1));
+            hole.Codes.Add(new LinearMove(0, 1));
+            var pgm = new Program(Mode.Absolute);
+            pgm.Codes.Add(new SubProgramCall { Id = 1, Program = hole, Offset = new Vector(5, 5) });
+
+            var segments = RapidEnumerator.Enumerate(pgm, new Vector(100, 200), Vector.Zero);
+
+            Assert.Equal(2, segments.Count);
+            Assert.Equal(new RapidEnumerator.Segment(Vector.Zero, new Vector(105, 205)), segments[0]);
+            Assert.Equal(new RapidEnumerator.Segment(new Vector(106, 205), new Vector(108, 206)), segments[1]);
+        }
+
         [Fact]
         public void Enumerate_SubProgramCall_RapidEndsAtAbsoluteHolePierce()
         {