feat: show stippled centering guides while dragging launcher

Sources/Conjure/LauncherAlignmentGuides.swift

@@ -0,0 +1,81 @@
+import AppKit
+
+@MainActor
+final class LauncherAlignmentGuides {
+    private let view = AlignmentGuideView()
+    private lazy var overlay: NSPanel = {
+        let panel = NSPanel(contentRect: .zero, styleMask: [.borderless, .nonactivatingPanel], backing: .buffered, defer: false)
+        panel.backgroundColor = .clear
+        panel.isOpaque = false
+        panel.hasShadow = false
+        panel.ignoresMouseEvents = true
+        panel.isReleasedWhenClosed = false
+        panel.collectionBehavior = [.moveToActiveSpace, .fullScreenAuxiliary]
+        panel.contentView = view
+        panel.setAccessibilityElement(false)
+        return panel
+    }()
+    private var dragging = false
+
+    func begin(for window: NSWindow) {
+        guard window.screen != nil else { return }
+        dragging = true
+        update(for: window)
+        overlay.level = window.level
+        overlay.order(.below, relativeTo: window.windowNumber)
+    }
+
+    func update(for window: NSWindow) {
+        guard dragging, let screen = window.screen else { return }
+        let frame = screen.visibleFrame
+        if overlay.frame != frame {
+            overlay.setFrame(frame, display: false)
+        }
+        view.launcherFrame = window.frame.offsetBy(dx: -frame.minX, dy: -frame.minY)
+        view.alignmentTolerance = 1 / screen.backingScaleFactor
+        view.needsDisplay = true
+    }
+
+    func end() {
+        guard dragging else { return }
+        dragging = false
+        overlay.orderOut(nil)
+    }
+}
+
+@MainActor
+private final class AlignmentGuideView: NSView {
+    var launcherFrame = NSRect.zero
+    var alignmentTolerance: CGFloat = 0.5
+    private static let dash: [CGFloat] = [1, 5]
+    private static let muted = SunsetPalette.accent.withAlphaComponent(0.4).cgColor
+    private static let aligned = SunsetPalette.accent.withAlphaComponent(0.95).cgColor
+    private static let shadow = NSColor.black.withAlphaComponent(0.6).cgColor
+
+    override func hitTest(_ point: NSPoint) -> NSView? { nil }
+
+    override func draw(_ dirtyRect: NSRect) {
+        guard let context = NSGraphicsContext.current?.cgContext else { return }
+        context.saveGState()
+        defer { context.restoreGState() }
+        context.addRect(bounds)
+        context.addRect(launcherFrame.insetBy(dx: -8, dy: -8))
+        context.clip(using: .evenOdd)
+        context.setLineWidth(1.5)
+        context.setLineCap(.round)
+        context.setLineDash(phase: 0, lengths: Self.dash)
+        context.setShadow(offset: .zero, blur: 2, color: Self.shadow)
+
+        let centeredX = abs(launcherFrame.midX - bounds.midX) <= alignmentTolerance
+        context.setStrokeColor(centeredX ? Self.aligned : Self.muted)
+        context.move(to: NSPoint(x: bounds.midX, y: bounds.minY))
+        context.addLine(to: NSPoint(x: bounds.midX, y: bounds.maxY))
+        context.strokePath()
+
+        let centeredY = abs(launcherFrame.midY - bounds.midY) <= alignmentTolerance
+        context.setStrokeColor(centeredY ? Self.aligned : Self.muted)
+        context.move(to: NSPoint(x: bounds.minX, y: bounds.midY))
+        context.addLine(to: NSPoint(x: bounds.maxX, y: bounds.midY))
+        context.strokePath()
+    }
+}

Sources/Conjure/LauncherWindowController.swift

@@ -15,6 +15,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
     private var discoveryTask: Task<Void, Never>?
     private var isLaunching = false
     private var previousApplication: NSRunningApplication?
+    private var alignmentGuides: LauncherAlignmentGuides?
 
     init(history: LaunchHistory = LaunchHistory()) {
         self.history = history
@@ -39,6 +40,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         window.delegate = self
         window.navigateSelection = { [weak self] offset in self?.moveSelection(by: offset) }
         window.dismiss = { [weak self] in self?.dismiss() }
+        window.dragEnded = { [weak self] in self?.alignmentGuides?.end() }
     }
 
     required init?(coder: NSCoder) {
@@ -72,6 +74,7 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
 
     func dismiss(restoringFocus: Bool = true) {
         guard !restoringFocus || (!isLaunching && window?.attachedSheet == nil) else { return }
+        alignmentGuides?.end()
         let previous = previousApplication
         previousApplication = nil
         window?.orderOut(nil)
@@ -81,6 +84,18 @@ final class LauncherWindowController: NSWindowController, NSWindowDelegate, NSSe
         }
     }
 
+    func windowWillMove(_ notification: Notification) {
+        guard let window else { return }
+        let guides = alignmentGuides ?? LauncherAlignmentGuides()
+        alignmentGuides = guides
+        guides.begin(for: window)
+    }
+
+    func windowDidMove(_ notification: Notification) {
+        guard let window else { return }
+        alignmentGuides?.update(for: window)
+    }
+
     func windowDidResignKey(_ notification: Notification) {
         guard !isLaunching, window?.attachedSheet == nil else { return }
         dismiss(restoringFocus: false)
@@ -473,6 +488,7 @@ private final class LauncherPanel: NSPanel {
     override var canBecomeMain: Bool { true }
     var navigateSelection: ((Int) -> Void)?
     var dismiss: (() -> Void)?
+    var dragEnded: (() -> Void)?
 
     override func sendEvent(_ event: NSEvent) {
         if event.type == .keyDown, attachedSheet == nil,
@@ -489,6 +505,9 @@ private final class LauncherPanel: NSPanel {
             }
         }
         super.sendEvent(event)
+        if event.type == .leftMouseDown || event.type == .leftMouseUp {
+            dragEnded?()
+        }
     }
 
     override func performClose(_ sender: Any?) {