fix(desktop): build macOS icns with sips + iconutil - #596
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wails3's encoder resizes with Mitchell-Netravali, whose negative lobe overshoots on the logo's high-contrast edges. The R channel clips at 0 while G/B keep mid values, leaving near-opaque dark pixels scattered over the red tile: 4 in the 64px layer, 13 at 128px, 23 at 256px. It also emits only 8 layers, missing icon_16x16 and icon_32x32, so Finder has to downscale a larger layer for small sizes. Generate the .iconset with sips and pack it with iconutil instead. All 10 layers are present and Core Graphics downsampling leaves no overshoot. generate:icons is split because sips and iconutil are macOS-only: the shared task keeps emitting the Windows .ico on every platform, while the new darwin-only task owns the .icns. Co-authored-by: Cursor <cursoragent@cursor.com>
liukewia
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September 7, 2026 11:26
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Problem
The Dock/Finder icon has visible dark specks at 64, 128 and 256 px.
wails3 generate iconsencodes the.icnsthroughjackmordaunt/icns, whichresizes with Mitchell-Netravali. Its negative lobe overshoots on the logo's
high-contrast edges (white glyph on red, squircle on transparent): the R channel
clips at 0 while G/B keep mid values, producing near-opaque teal-black pixels
such as
(1, 51, 54, 254)scattered across the red tile.Measured against the source image's opaque RGB gamut:
That encoder also emits only 8 layers. Its smallest osType is 32px (
ic11),which icns treats as
icon_16x16@2x— soicon_16x16andicon_32x32areabsent and Finder downscales a larger layer for small sizes.
Change
Build the
.iconsetwithsips -zand pack it withiconutil. All 10 layersare present, and Core Graphics downsampling leaves no overshoot.
generate:iconsis split becausesips/iconutilare macOS-only: the sharedtask still emits the Windows
.icoon every platform, and the newgenerate:icons:darwinowns the.icns. The darwin build depends on the latter(it never needed the Windows
.ico).Verification
Not covered: the source
appicon-macos.pngcarries black RGB in itssemi-transparent edge (4138 px at alpha 6-9, RGB ~
(39,30,30)) — non-premultipliedexport without edge extend. It tints the 256px edge band but stays under
alpha 120, so it is not the speck problem above and would need a fix in the
design source, not the packaging script.