fix: drop glare holes before the margin and never auto-pick specks

Filtering holes after the margin let -2 mm grow 1 mm specks past the
3 mm cutoff, and could drop real holes shrunk by a positive margin.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/detect.test.ts

@@ -11,7 +11,7 @@ beforeAll(async () => {
 });
 
 const params = (overrides: Partial<DetectParams> = {}): DetectParams => ({
-  threshold: 128, invert: false, seed: null, marginPx: 0, ...overrides,
+  threshold: 128, invert: false, seed: null, marginPx: 0, minHolePx: 0, ...overrides,
 });
 
 /** Light plate x 40..159, y 30..129 with hole r=15 at (100,80), plus a small light blob, on dark ground. */
@@ -84,4 +84,23 @@ describe('detect', () => {
     });
     expect(detect(cv, speckled, params())!.holes).toHaveLength(0);
   });
+
+  it('fills specks smaller than minHolePx before the margin can grow them', () => {
+    const glare = grayImage(200, 160, (x, y) => {
+      const plate = inRect(x, y, 40, 30, 160, 130) && !inCircle(x, y, 100, 80, 15) && !inCircle(x, y, 60, 50, 3);
+      return plate ? 220 : 30;
+    });
+    expect(detect(cv, glare, params({ marginPx: -6 }))!.holes).toHaveLength(2);
+    expect(detect(cv, glare, params({ marginPx: -6, minHolePx: 10 }))!.holes).toHaveLength(1);
+  });
+
+  it('keeps a long thin hole that is under minHolePx in only one direction', () => {
+    const slotted = grayImage(200, 160, (x, y) => (inRect(x, y, 40, 30, 160, 130) && !inRect(x, y, 60, 60, 120, 66) ? 220 : 30));
+    expect(detect(cv, slotted, params({ minHolePx: 10 }))!.holes).toHaveLength(1);
+  });
+
+  it('does not auto-pick a speck when the real piece touches the border', () => {
+    const framed = grayImage(400, 300, (x, y) => (inRect(x, y, 0, 60, 240, 260) || inRect(x, y, 330, 100, 340, 110) ? 220 : 30));
+    expect(detect(cv, framed, params())).toBeNull();
+  });
 });

tests/fixtures.test.ts

@@ -34,7 +34,7 @@ describe.skipIf(cases.length === 0)('detect on real photos', () => {
   it.each(cases)('$file', (c) => {
     const image = readJpeg(dir + c.file);
     const threshold = c.threshold ?? otsuThreshold(cv, image);
-    const shape = detect(cv, image, { threshold, invert: c.invert, seed: c.seed, marginPx: 0 });
+    const shape = detect(cv, image, { threshold, invert: c.invert, seed: c.seed, marginPx: 0, minHolePx: 3 * c.pxPerMm });
     expect(shape).not.toBeNull();
     const mm = prepareForExport(shape!, c.pxPerMm)!;
     const size = shapeSize(mm);

tests/geometry.test.ts

@@ -53,20 +53,9 @@ describe('prepareForExport', () => {
     expect(mm.outer).toHaveLength(4);
   });
 
-  it('drops holes smaller than 3 mm in both directions (glare/speckle)', () => {
-    const shapePx = {
-      outer: denseSquare(0, 0, 400),
-      holes: [denseSquare(100, 100, 8), denseSquare(200, 200, 40)], // 2 mm and 10 mm at 4 px/mm
-    };
-    const mm = prepareForExport(shapePx, 4)!;
-    expect(mm.holes).toHaveLength(1);
-    expect(shapeSize({ outer: mm.holes[0], holes: [] }).width).toBeCloseTo(10);
-  });
-
-  it('keeps a long thin hole that is under 3 mm in only one direction', () => {
-    const slot: Point[] = [{ x: 100, y: 100 }, { x: 300, y: 100 }, { x: 300, y: 104 }, { x: 100, y: 104 }];
-    const mm = prepareForExport({ outer: denseSquare(0, 0, 400), holes: [slot] }, 4)!;
-    expect(mm.holes).toHaveLength(1);
+  it('keeps every hole, however small (speck filtering happens before the margin)', () => {
+    const shapePx = { outer: denseSquare(0, 0, 400), holes: [denseSquare(100, 100, 8), denseSquare(200, 200, 40)] };
+    expect(prepareForExport(shapePx, 4)!.holes).toHaveLength(2);
   });
 
   it('returns null when the outer ring degenerates', () => {