refactor: address gemini review round 2 on PR #52

- BarcodeObject: revert textElements guard from Array.isArray to truthy
  check. Non-EAN rotated barcodes assign a single ReactNode (not an
  array), which the stricter check incorrectly filtered out, killing
  HRI text rendering.
- snapGuides.computePointSnap: allow snapping to the label rect's
  centre in addition to its edges. Neighbour objects stay edge-only so
  the original 50%-snap regression remains fixed.

Author: u8array

src/components/Canvas/BarcodeObject.tsx

@@ -695,7 +695,7 @@ export function BarcodeObject({
             strokeWidth={isSelected ? 2 : 0}
             strokeScaleEnabled={false}
           />
-          {Array.isArray(textElements) && textElements.length > 0 && (
+          {textElements && (
             <Group ref={excludeGroupFromBbox}>{textElements}</Group>
           )}
         </Group>

src/lib/snapGuides.test.ts

@@ -192,9 +192,21 @@ describe("computePointSnap", () => {
 
   it("uses the label rect for edge alignment too", () => {
     const lbl = r("_lbl", 0, 0, 1000, 600);
+    // y=300 sits exactly on the label's vertical centre — a valid
+    // label-centre snap, so two guides fire (right edge + centre).
     const result = computePointSnap({ x: 998, y: 300 }, [], 6, lbl);
     expect(result.x).toBe(1000); // right edge of label
-    expect(result.guides).toHaveLength(1);
+    expect(result.y).toBe(300);  // label vertical centre
+    expect(result.guides).toHaveLength(2);
+  });
+
+  it("snaps to label centre (allowed for label only, not for neighbour objects)", () => {
+    const lbl = r("_lbl", 0, 0, 1000, 600);
+    // Point near horizontal centre of label (500, 300).
+    const result = computePointSnap({ x: 502, y: 302 }, [], 6, lbl);
+    expect(result.x).toBe(500);
+    expect(result.y).toBe(300);
+    expect(result.guides).toHaveLength(2);
   });
 
   it("respects the threshold — far targets are ignored", () => {

src/lib/snapGuides.ts

@@ -55,11 +55,18 @@ export function computePointSnap(
       consider(endEdge, perpStart, perpEnd);
     }
     if (labelRect) {
+      // Label edges *and* center are valid endpoint snap targets. Centre
+      // is intentionally only allowed for the label (not for other
+      // objects) — endpoint alignment to a neighbour's midpoint produced
+      // the "50 %" artefact this helper was created to avoid.
       const startEdge = axis === 'x' ? labelRect.x : labelRect.y;
-      const endEdge = startEdge + (axis === 'x' ? labelRect.width : labelRect.height);
+      const size = axis === 'x' ? labelRect.width : labelRect.height;
+      const endEdge = startEdge + size;
+      const center = startEdge + size / 2;
       const perpStart = axis === 'x' ? labelRect.y : labelRect.x;
       const perpEnd = perpStart + (axis === 'x' ? labelRect.height : labelRect.width);
       consider(startEdge, perpStart, perpEnd);
+      consider(center, perpStart, perpEnd);
       consider(endEdge, perpStart, perpEnd);
     }
     return { value: bestValue, guides: bestGuides };