diff --git a/build/icon.icns b/build/icon.icns
index 833a2f1a67..9b96da0eb7 100644
Binary files a/build/icon.icns and b/build/icon.icns differ
diff --git a/tools/generate-mac-icon.js b/tools/generate-mac-icon.js
new file mode 100644
index 0000000000..67cabc913e
--- /dev/null
+++ b/tools/generate-mac-icon.js
@@ -0,0 +1,119 @@
+#!/usr/bin/env node
+
+/**
+ * Generate macOS app icon with squircle mask from existing PNG source.
+ *
+ * macOS does not automatically apply a squircle mask to .icns icons —
+ * the shape must be baked into the image. This script applies an
+ * Apple-standard squircle (rounded rect with ~18% corner radius)
+ * to the square source icon and generates build/icon.icns.
+ *
+ * The .icns file is assembled directly from PNG buffers (no native tools needed).
+ */
+
+const sharp = require('sharp');
+const fs = require('fs');
+const path = require('path');
+
+const SOURCE_PNG = path.join(__dirname, '../build/icons/sq2160x2160.png');
+const OUTPUT_ICNS = path.join(__dirname, '../build/icon.icns');
+
+// ICNS OSType codes for PNG-based entries, mapped by pixel size
+// See: https://en.wikipedia.org/wiki/Apple_Icon_Image_format
+const ICNS_TYPES = [
+  { osType: 'ic10', size: 1024 },
+  { osType: 'ic09', size: 512 },
+  { osType: 'ic08', size: 256 },
+  { osType: 'ic07', size: 128 },
+  { osType: 'icp5', size: 32 },
+  { osType: 'icp4', size: 16 },
+];
+
+function squircleSvg(size) {
+  const radius = Math.round(size * 0.18);
+  return `<svg width="${size}" height="${size}">
+  <rect x="0" y="0" width="${size}" height="${size}" rx="${radius}" ry="${radius}" fill="white"/>
+</svg>`;
+}
+
+function buildIcns(entries) {
+  // ICNS file format:
+  // Header: 4 bytes magic ('icns') + 4 bytes total file size
+  // Entries: 4 bytes OSType + 4 bytes entry size (including header) + PNG data
+  const HEADER_SIZE = 8;
+  const ENTRY_HEADER_SIZE = 8;
+
+  let totalSize = HEADER_SIZE;
+  for (const entry of entries) {
+    totalSize += ENTRY_HEADER_SIZE + entry.data.length;
+  }
+
+  const buffer = Buffer.alloc(totalSize);
+  let offset = 0;
+
+  // File header
+  buffer.write('icns', offset, 4, 'ascii');
+  offset += 4;
+  buffer.writeUInt32BE(totalSize, offset);
+  offset += 4;
+
+  // Entries
+  for (const entry of entries) {
+    buffer.write(entry.osType, offset, 4, 'ascii');
+    offset += 4;
+    buffer.writeUInt32BE(ENTRY_HEADER_SIZE + entry.data.length, offset);
+    offset += 4;
+    entry.data.copy(buffer, offset);
+    offset += entry.data.length;
+  }
+
+  return buffer;
+}
+
+async function generateMacIcon() {
+  console.log('Generating macOS app icon with squircle mask...\n');
+
+  if (!fs.existsSync(SOURCE_PNG)) {
+    throw new Error(`Source PNG not found: ${SOURCE_PNG}`);
+  }
+  console.log('Source PNG found:', SOURCE_PNG);
+
+  const entries = [];
+
+  for (const { osType, size } of ICNS_TYPES) {
+    const svg = squircleSvg(size);
+
+    const pngBuffer = await sharp(SOURCE_PNG)
+      .resize(size, size, { fit: 'cover', position: 'center' })
+      .composite([{ input: Buffer.from(svg), blend: 'dest-in' }])
+      .flatten({ background: { r: 255, g: 255, b: 255 } })
+      .removeAlpha()
+      .png()
+      .toBuffer();
+
+    entries.push({ osType, data: pngBuffer });
+    console.log(`  Generated ${size}x${size} (${osType}, ${pngBuffer.length} bytes)`);
+  }
+
+  // Build and write .icns file
+  console.log('\nAssembling .icns file...');
+  const icnsBuffer = buildIcns(entries);
+  fs.writeFileSync(OUTPUT_ICNS, icnsBuffer);
+
+  const stats = fs.statSync(OUTPUT_ICNS);
+  console.log(`Generated: ${OUTPUT_ICNS} (${stats.size} bytes)`);
+
+  // Verify the largest entry has no alpha
+  const metadata = await sharp(entries[0].data).metadata();
+  console.log(`\nVerification (1024px entry):`);
+  console.log(`  Dimensions: ${metadata.width}x${metadata.height}`);
+  console.log(`  Channels: ${metadata.channels} (${metadata.hasAlpha ? 'RGBA' : 'RGB'})`);
+  console.log(`  Has alpha: ${metadata.hasAlpha ? 'YES (unexpected)' : 'NO (correct)'}`);
+
+  console.log('\nDone! macOS squircle icon generated at build/icon.icns');
+}
+
+generateMacIcon().catch((error) => {
+  console.error('\nError generating icon:', error.message);
+  process.exit(1);
+});