Fix drawing canvas corner artifacts at rounded panel edges.

Clip and round the blank canvas fill on the left side so white no longer bleeds past the panel border.

Co-authored-by: Cursor <cursoragent@cursor.com>

smart_printer/DrawPrintView.swift

@@ -135,7 +135,6 @@ final class DrawPrintOverlayView: NSView, AppearanceRefreshable {
         canvasContainer.wantsLayer = true
         canvasContainer.layer?.cornerRadius = AppTheme.contentPanelCornerRadius
         canvasContainer.layer?.borderWidth = 1.5
-        canvasContainer.clipsToBounds = false
         canvasContainer.applyCardShadow()
         canvasContainer.translatesAutoresizingMaskIntoConstraints = false
 
@@ -289,6 +288,9 @@ final class BlankCanvasView: NSView, AppearanceRefreshable {
 
     private func setup() {
         wantsLayer = true
+        layer?.cornerRadius = AppTheme.contentPanelCornerRadius
+        layer?.maskedCorners = [.layerMinXMinYCorner, .layerMinXMaxYCorner]
+        layer?.masksToBounds = true
 
         undoButton.translatesAutoresizingMaskIntoConstraints = false
         redoButton.translatesAutoresizingMaskIntoConstraints = false
@@ -314,7 +316,7 @@ final class BlankCanvasView: NSView, AppearanceRefreshable {
 
     override func draw(_ dirtyRect: NSRect) {
         NSColor.white.setFill()
-        bounds.fill()
+        leftRoundedFillPath().fill()
 
         let context = NSGraphicsContext.current?.cgContext
         for stroke in strokes {
@@ -330,6 +332,31 @@ final class BlankCanvasView: NSView, AppearanceRefreshable {
         }
     }
 
+    private func leftRoundedFillPath() -> NSBezierPath {
+        let radius = AppTheme.contentPanelCornerRadius
+        let rect = bounds
+        let path = NSBezierPath()
+        path.move(to: NSPoint(x: rect.minX + radius, y: rect.maxY))
+        path.line(to: NSPoint(x: rect.maxX, y: rect.maxY))
+        path.line(to: NSPoint(x: rect.maxX, y: rect.minY))
+        path.line(to: NSPoint(x: rect.minX + radius, y: rect.minY))
+        path.appendArc(
+            withCenter: NSPoint(x: rect.minX + radius, y: rect.minY + radius),
+            radius: radius,
+            startAngle: 180,
+            endAngle: 270
+        )
+        path.line(to: NSPoint(x: rect.minX, y: rect.maxY - radius))
+        path.appendArc(
+            withCenter: NSPoint(x: rect.minX + radius, y: rect.maxY - radius),
+            radius: radius,
+            startAngle: 90,
+            endAngle: 180
+        )
+        path.close()
+        return path
+    }
+
     private func drawStroke(_ stroke: CanvasStroke, in context: CGContext?) {
         guard stroke.points.count > 1, let context else { return }
         context.saveGState()