fix: parser skips non-drawing moves; clean up TS build

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/gcode/parser.test.ts

@@ -47,4 +47,23 @@ describe('parseGcode', () => {
     expect(segments).toHaveLength(1);
     expect(warnings).toHaveLength(0);
   });
+
+  it('does not emit segments for pure-Z plunge moves but keeps drawing XY after', () => {
+    const { segments } = parseGcode(`G21 G90\nG1 X5 Y0\nG1 Z-3\nG1 X10 Y0`);
+    expect(segments).toHaveLength(2);
+    expect(segments[1]!.points).toEqual([[5, 0], [10, 0]]);
+  });
+
+  it('does not emit a segment or warning for a bare motion word', () => {
+    const { segments, warnings } = parseGcode(`G21 G90\nG2\nG1 X5 Y0`);
+    expect(segments).toHaveLength(1);
+    expect(warnings).toHaveLength(0);
+  });
+
+  it('still flattens a full-circle arc where start == end', () => {
+    const { segments } = parseGcode(`G21 G90\nG0 X10 Y0\nG2 X10 Y0 I-10 J0`);
+    const arc = segments[1]!;
+    expect(arc.kind).toBe('cut');
+    expect(arc.points.length).toBeGreaterThan(4);
+  });
 });

src/gcode/parser.ts

@@ -39,13 +39,11 @@ export function parseGcode(text: string): ParseResult {
     }
 
     const axis: Record<string, number> = {};
-    let motionThisLine: number | null = null;
     for (const [letter, value] of words) {
       switch (letter) {
         case 'G':
           if (value === 0 || value === 1 || value === 2 || value === 3) {
             st.motion = value;
-            motionThisLine = value;
           } else if (value === 20) st.scale = 25.4;
           else if (value === 21) st.scale = 1;
           else if (value === 90) st.absolute = true;
@@ -61,8 +59,12 @@ export function parseGcode(text: string): ParseResult {
       }
     }
 
-    const hasCoord = 'X' in axis || 'Y' in axis || 'Z' in axis;
-    if (motionThisLine === null && !hasCoord) continue; // no movement on this line
+    if ('Z' in axis) st.z = axis['Z']!; // track depth even on pure-Z moves
+    const hasXY = 'X' in axis || 'Y' in axis;
+    const hasArc = 'I' in axis || 'J' in axis || 'R' in axis;
+    // Only XY motion (or an arc, including full circles) yields a drawable segment.
+    // This skips bare motion words (e.g. `G1`), pure-Z plunges, and modal/comment lines.
+    if (!hasXY && !hasArc) continue;
 
     const start: Vec2 = [st.x, st.y];
     const target = resolveTarget(st, axis);
@@ -88,7 +90,6 @@ export function parseGcode(text: string): ParseResult {
     }
     st.x = target[0];
     st.y = target[1];
-    if ('Z' in axis) st.z = axis['Z']!;
   }
 
   return { segments, warnings };

src/geometry/arc.test.ts

@@ -17,7 +17,7 @@ describe('flattenArc', () => {
   it('CW arc sweeps the other way (midpoint has negative y)', () => {
     // centre (0,0), radius 10, from (10,0) CW to (0,10) → goes the long way through y<0
     const pts = flattenArc([10, 0], [0, 10], [0, 0], true, 0.1);
-    const mid = pts[Math.floor(pts.length / 2)];
+    const mid = pts[Math.floor(pts.length / 2)]!;
     expect(mid[1]).toBeLessThan(0);
   });