Round window-capture corners with a clip instead of masking()

The masking() call could silently fail against ScreenCaptureKit's pixel
format, leaving sharp corners. Clip to a rounded path and redraw instead,
verified headlessly for corner clipping and orientation.

💘 Generated with Crush

Assisted-by: Crush:deepseek-v4-flash-0731

Sources/Kapture/CaptureController.swift

@@ -402,23 +402,19 @@ final class ScreenCapture {
         // Apply a rounded-corner alpha mask for window captures, matching
         // macOS window chrome (≈10pt radius, scaled to image pixels).
         if roundedCorners {
+            // Clip to a rounded rect and redraw — deterministic corner alpha
+            // (masking() can fail depending on the source pixel format).
             let radius = 10 * scaleX
-            let maskRect = CGRect(x: 0, y: 0, width: result.width, height: result.height)
-            guard let maskCtx = CGContext(
+            guard let ctx = CGContext(
                 data: nil, width: result.width, height: result.height,
                 bitsPerComponent: 8, bytesPerRow: 0,
                 space: CGColorSpaceCreateDeviceRGB(),
                 bitmapInfo: CGImageAlphaInfo.premultipliedLast.rawValue
             ) else { return result }
-            maskCtx.setFillColor(CGColor(gray: 1, alpha: 1))
-            maskCtx.fill(maskRect)
-            maskCtx.setBlendMode(.clear)
-            maskCtx.setFillColor(CGColor(gray: 0, alpha: 1))
-            maskCtx.addPath(CGPath(roundedRect: maskRect, cornerWidth: radius, cornerHeight: radius, transform: nil))
-            maskCtx.fillPath()
-            maskCtx.setBlendMode(.normal)
-            if let mask = maskCtx.makeImage(),
-               let masked = result.masking(mask) {
+            ctx.addPath(CGPath(roundedRect: CGRect(x: 0, y: 0, width: result.width, height: result.height), cornerWidth: radius, cornerHeight: radius, transform: nil))
+            ctx.clip()
+            ctx.draw(result, in: CGRect(x: 0, y: 0, width: result.width, height: result.height))
+            if let masked = ctx.makeImage() {
                 result = masked
             }
         }