Support dropping folders onto the dock icon

Resources/Info.plist

@@ -12,6 +12,21 @@
 	<string>$(PRODUCT_BUNDLE_IDENTIFIER)</string>
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
+	<key>CFBundleDocumentTypes</key>
+	<array>
+		<dict>
+			<key>CFBundleTypeName</key>
+			<string>Folder</string>
+			<key>CFBundleTypeRole</key>
+			<string>Viewer</string>
+			<key>LSHandlerRank</key>
+			<string>Alternate</string>
+			<key>LSItemContentTypes</key>
+			<array>
+				<string>public.folder</string>
+			</array>
+		</dict>
+	</array>
 	<key>CFBundleName</key>
 	<string>$(PRODUCT_NAME)</string>
 	<key>CFBundlePackageType</key>

Sources/AppDelegate.swift

@@ -368,13 +368,24 @@ enum FinderServicePathResolver {
         return canonical
     }
 
+    private static func resolvedDirectoryURL(from url: URL) -> URL {
+        let standardized = url.standardizedFileURL
+        if standardized.hasDirectoryPath {
+            return standardized
+        }
+        if let resourceValues = try? standardized.resourceValues(forKeys: [.isDirectoryKey]),
+           resourceValues.isDirectory == true {
+            return standardized
+        }
+        return standardized.deletingLastPathComponent()
+    }
+
     static func orderedUniqueDirectories(from pathURLs: [URL]) -> [String] {
         var seen: Set<String> = []
         var directories: [String] = []
 
         for url in pathURLs {
-            let standardized = url.standardizedFileURL
-            let directoryURL = standardized.hasDirectoryPath ? standardized : standardized.deletingLastPathComponent()
+            let directoryURL = resolvedDirectoryURL(from: url)
             let path = canonicalDirectoryPath(directoryURL.path(percentEncoded: false))
             guard !path.isEmpty else { continue }
             if seen.insert(path).inserted {
@@ -2154,6 +2165,19 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         Self.shared = self
     }
 
+    func application(_ application: NSApplication, open urls: [URL]) {
+        let directories = externalOpenDirectories(from: urls)
+        guard !directories.isEmpty else { return }
+
+        prepareForExplicitOpenIntentAtStartup()
+        for directory in directories {
+            openWorkspaceForExternalDirectory(
+                workingDirectory: directory,
+                debugSource: "application.openURLs"
+            )
+        }
+    }
+
     func applicationDidFinishLaunching(_ notification: Notification) {
         let env = ProcessInfo.processInfo.environment
         let isRunningUnderXCTest = isRunningUnderXCTest(env)
@@ -5077,19 +5101,15 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
         target: ServiceOpenTarget,
         error: AutoreleasingUnsafeMutablePointer<NSString>
     ) {
-        didHandleExplicitOpenIntentAtStartup = true
-        if !didAttemptStartupSessionRestore {
-            startupSessionSnapshot = nil
-            didAttemptStartupSessionRestore = true
-        }
+        prepareForExplicitOpenIntentAtStartup()
 
         let pathURLs = servicePathURLs(from: pasteboard)
         guard !pathURLs.isEmpty else {
             error.pointee = Self.serviceErrorNoPath
             return
         }
 
-        let directories = FinderServicePathResolver.orderedUniqueDirectories(from: pathURLs)
+        let directories = externalOpenDirectories(from: pathURLs)
         guard !directories.isEmpty else {
             error.pointee = Self.serviceErrorNoPath
             return
@@ -5134,10 +5154,32 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
     }
 
     private func openWorkspaceFromService(workingDirectory: String) {
+        openWorkspaceForExternalDirectory(
+            workingDirectory: workingDirectory,
+            debugSource: "service.openTab"
+        )
+    }
+
+    private func prepareForExplicitOpenIntentAtStartup() {
+        didHandleExplicitOpenIntentAtStartup = true
+        if !didAttemptStartupSessionRestore {
+            startupSessionSnapshot = nil
+            didAttemptStartupSessionRestore = true
+        }
+    }
+
+    private func externalOpenDirectories(from urls: [URL]) -> [String] {
+        FinderServicePathResolver.orderedUniqueDirectories(from: urls.filter { $0.isFileURL })
+    }
+
+    private func openWorkspaceForExternalDirectory(
+        workingDirectory: String,
+        debugSource: String
+    ) {
         if addWorkspaceInPreferredMainWindow(
             workingDirectory: workingDirectory,
             shouldBringToFront: true,
-            debugSource: "service.openTab"
+            debugSource: debugSource
         ) != nil {
             return
         }

cmuxTests/CmuxWebViewKeyEquivalentTests.swift

@@ -1197,6 +1197,55 @@ final class AppDelegateWindowContextRoutingTests: XCTestCase {
         XCTAssertEqual(managerB.tabs.count, originalTabCountB + 1)
         XCTAssertTrue(managerB.tabs.contains(where: { $0.id == createdWorkspaceId }))
     }
+
+    func testApplicationOpenURLsAddsWorkspaceForDroppedFolderURL() throws {
+        _ = NSApplication.shared
+        let app = AppDelegate()
+
+        let windowId = UUID()
+        let window = makeMainWindow(id: windowId)
+        defer { window.orderOut(nil) }
+
+        let manager = TabManager()
+        app.registerMainWindow(
+            window,
+            windowId: windowId,
+            tabManager: manager,
+            sidebarState: SidebarState(),
+            sidebarSelectionState: SidebarSelectionState()
+        )
+
+        window.makeKeyAndOrderFront(nil)
+        _ = app.synchronizeActiveMainWindowContext(preferredWindow: window)
+
+        let defaults = UserDefaults.standard
+        let previousWelcomeShown = defaults.object(forKey: WelcomeSettings.shownKey)
+        defaults.set(true, forKey: WelcomeSettings.shownKey)
+        defer {
+            if let previousWelcomeShown {
+                defaults.set(previousWelcomeShown, forKey: WelcomeSettings.shownKey)
+            } else {
+                defaults.removeObject(forKey: WelcomeSettings.shownKey)
+            }
+        }
+
+        let rootDirectory = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
+            .appendingPathComponent(UUID().uuidString, isDirectory: true)
+        let droppedDirectory = rootDirectory.appendingPathComponent("project", isDirectory: true)
+        try FileManager.default.createDirectory(at: droppedDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(at: rootDirectory) }
+
+        let existingWorkspaceIds = Set(manager.tabs.map(\.id))
+
+        app.application(
+            NSApplication.shared,
+            open: [URL(fileURLWithPath: droppedDirectory.path)]
+        )
+
+        let createdWorkspace = manager.tabs.first { !existingWorkspaceIds.contains($0.id) }
+        XCTAssertNotNil(createdWorkspace)
+        XCTAssertEqual(createdWorkspace?.currentDirectory, droppedDirectory.path)
+    }
 }
 
 @MainActor