Add URL scheme support for external trigger integration

Register snippingtool:// URL scheme so external tools (Logitech Options,
Shortcuts, Stream Deck) can trigger specific capture modes directly.
Adds AppDelegate for reliable URL handling in MenuBarExtra-only apps.

Supported URLs:
  snippingtool://fullscreen
  snippingtool://window
  snippingtool://region

Co-Authored-By: Claude <noreply@anthropic.com>

Sources/AppCoordinator.swift

@@ -92,6 +92,35 @@ final class AppCoordinator: ObservableObject {
         }
     }
 
+    // MARK: - External triggers (URL scheme)
+
+    /// Handles `snippingtool://<mode>` URLs so external tools (Logitech
+    /// Options, Shortcuts, Stream Deck, `open` from the command line, …)
+    /// can trigger a specific capture mode instead of just launching the app.
+    /// Accepts the mode either as the host (`snippingtool://region`) or as
+    /// a query item (`snippingtool://capture?mode=region`).
+    func handle(url: URL) {
+        guard url.scheme?.caseInsensitiveCompare("snippingtool") == .orderedSame else { return }
+
+        let modeString = url.host?.lowercased()
+            ?? URLComponents(url: url, resolvingAgainstBaseURL: false)?
+                .queryItems?
+                .first(where: { $0.name.caseInsensitiveCompare("mode") == .orderedSame })?
+                .value?
+                .lowercased()
+
+        switch modeString {
+        case "fullscreen", "full", "full-screen", "screen":
+            capture(mode: .fullScreen)
+        case "window":
+            capture(mode: .window)
+        case "region", "area", "selection":
+            capture(mode: .region)
+        default:
+            NSLog("SnippingTool: unrecognized URL trigger \(url.absoluteString)")
+        }
+    }
+
     // MARK: - Capture
 
     func capture(mode: CaptureMode) {

Sources/AppDelegate.swift

@@ -0,0 +1,15 @@
+import AppKit
+
+/// MenuBarExtra-only apps (no WindowGroup) don't reliably receive SwiftUI's
+/// `.onOpenURL` scene events — SwiftUI logs "Cannot use Scene methods for
+/// URL... without using SwiftUI Lifecycle" and the handler never fires.
+/// The classic AppKit delegate callback works regardless, so URL scheme
+/// triggers (from Logitech Options, Shortcuts, Stream Deck, `open`, …) are
+/// routed through here instead.
+final class AppDelegate: NSObject, NSApplicationDelegate {
+    let coordinator = AppCoordinator()
+
+    func application(_ application: NSApplication, open urls: [URL]) {
+        urls.forEach { coordinator.handle(url: $0) }
+    }
+}

Sources/SnippingToolApp.swift

@@ -2,12 +2,12 @@ import SwiftUI
 
 @main
 struct SnippingToolApp: App {
-    @StateObject private var coordinator = AppCoordinator()
+    @NSApplicationDelegateAdaptor(AppDelegate.self) private var appDelegate
 
     var body: some Scene {
         MenuBarExtra("Snipping Tool", systemImage: "camera.viewfinder") {
             MenuBarContentView()
-                .environmentObject(coordinator)
+                .environmentObject(appDelegate.coordinator)
         }
         .menuBarExtraStyle(.menu)
     }

project.yml

@@ -18,6 +18,10 @@ targets:
         CFBundleName: Snipping Tool
         LSUIElement: true
         NSHumanReadableCopyright: "Copyright © 2026"
+        CFBundleURLTypes:
+          - CFBundleURLName: it.wende.snippingtool
+            CFBundleURLSchemes:
+              - snippingtool
     settings:
       base:
         PRODUCT_BUNDLE_IDENTIFIER: it.wende.snippingtool