oraculo-radiohead: Skill for Cursor

Desktop Principles

Desktop UX context. Loaded when desktop is detected (macOS, Windows, Linux desktop, web desktop). Concise rules here. Deep-dive in references/.

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Hover States Are Mandatory

Hover is the primary affordance signal on desktop, the inverse of mobile. A pointer hovering over a target without immediate visual feedback feels broken: users rely on :hover to confirm an element is interactive before committing to a click. Every clickable surface must have a distinct hover style, ideally with a 100-200ms transition so the change is perceptible without feeling sluggish.

CSS - hover styles for interactive elements:

.button {
  background: var(--surface);
  transition: background 120ms ease-out, transform 120ms ease-out;
}

.button:hover {
  background: var(--surface-hover);
  transform: translateY(-1px);
}

.button:active {
  transform: translateY(0);
}

SwiftUI - .onHover for macOS, .hoverEffect for iPadOS:

struct ToolbarButton: View {
  @State private var hovering = false

  var body: some View {
    Image(systemName: "square.and.arrow.up")
      .padding(8)
      .background(hovering ? Color.gray.opacity(0.15) : .clear)
      .onHover { hovering = $0 }
      .animation(.easeOut(duration: 0.12), value: hovering)
      .hoverEffect(.highlight) // iPadOS pointer support, no-op on macOS
  }
}

Compose Desktop - onPointerEvent or hoverable + interactionSource:

@OptIn(ExperimentalComposeUiApi::class)
@Composable
fun ToolbarButton(onClick: () -> Unit) {
  val interactionSource = remember { MutableInteractionSource() }
  val hovered by interactionSource.collectIsHoveredAsState()

  Box(
    modifier = Modifier
      .hoverable(interactionSource)
      .background(if (hovered) Color.LightGray.copy(alpha = 0.15f) else Color.Transparent)
      .clickable(onClick = onClick)
      .padding(8.dp),
  ) { Icon(Icons.Default.Share, contentDescription = "Share") }
}

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Pointer Precision

Mouse and trackpad pointers are far more accurate than thumbs, so desktop targets can be smaller than the 44pt mobile minimum. Common ranges are 24-32px for icon buttons, 28-36px for toolbar items. WCAG 2.5.8 (AA, target size minimum) sets the absolute floor at 24x24 CSS pixels for non-mobile pointer input. Sub-24px targets need spacing or be grouped with sibling targets.