Fix multi-file drag-and-drop and debounce FSEvents full rescans

- Properly create one NSItemProvider per dragged file
- Expose dragItemProviders for multi-item external drag support
- Clear providers on drag end
- Add debounce protection against duplicate full rescans from bursty FSEvents
- Suppress repeated full rescans within 1s window

This fixes external drag copying only a single file
and reduces UI freezes caused by duplicate full rescans.

Author: Iakov Senatov

GUI/Sources/ContextMenu/Services/OpenWithService.swift

@@ -82,16 +82,14 @@ final class OpenWithService {
     func getApplications(for fileURL: URL) -> [AppInfo] {
         let cacheKey = fileURL.path as NSString
         if let cached = OpenWithService.appsCache.object(forKey: cacheKey) as? [AppInfo] {
-            log.debug("\(#function) cache hit for '\(fileURL.lastPathComponent)' (\(cached.count) apps)")
+            //log.debug("\(#function) cache hit for '\(fileURL.lastPathComponent)' (\(cached.count) apps)")
             return cached
         }
-        log.debug("\(#function) file='\(fileURL.lastPathComponent)' ext=\(fileURL.pathExtension)")
-
+        //log.debug("\(#function) file='\(fileURL.lastPathComponent)' ext=\(fileURL.pathExtension)")
         guard UTType(filenameExtension: fileURL.pathExtension) != nil else {
-            log.warning("\(#function) unknown UTType for ext='\(fileURL.pathExtension)', using fallback editors")
+            //log.warning("\(#function) unknown UTType for ext='\(fileURL.pathExtension)', using fallback editors")
             return getAllEditors()
         }
-
         let defaultApp = workspace.urlForApplication(toOpen: fileURL)
         var apps: [AppInfo] = []
         var seenBundles = Set<String>()
@@ -242,7 +240,7 @@ final class OpenWithService {
             return makeAppInfo(from: url, isDefault: false)
         }
 
-        log.debug("\(#function) returning \(editors.count) fallback editors")
+        //log.debug("\(#function) returning \(editors.count) fallback editors")
         return editors
     }
 }

GUI/Sources/DragDrop/DragDropManager.swift

@@ -23,19 +23,31 @@ final class DragDropManager {
     /// Currently dragged files (for visual feedback)
     var draggedFiles: [CustomFile] = []
 
+    /// NSPasteboard providers for current drag session
+    var dragItemProviders: [NSItemProvider] = []
+
     /// Currently highlighted drop target (folder or panel)
     var dropTargetPath: URL?
 
     // MARK: - Start dragging files
     func startDrag(files: [CustomFile], from panelSide: PanelSide) {
         log.debug("DragDropManager: started dragging \(files.count) items from \(panelSide)")
+
         draggedFiles = files
+
+        // Create one NSItemProvider per file (required for multi-file drag)
+        dragItemProviders = files.map { file in
+            let provider = NSItemProvider(object: file.urlValue as NSURL)
+            provider.suggestedName = file.nameStr
+            return provider
+        }
     }
 
     // MARK: - End drag operation
     func endDrag() {
         log.debug("DragDropManager: drag ended")
         draggedFiles = []
+        dragItemProviders = []
         dropTargetPath = nil
     }
 

GUI/Sources/Services/Scanner/FSEventsDirectoryWatcher.swift

@@ -47,6 +47,10 @@ final class FSEventsDirectoryWatcher: @unchecked Sendable {
     private var pendingWork: DispatchWorkItem?
     private let throttleDelay: TimeInterval = 0.3
 
+    // Full-rescan protection (avoid duplicate rescans from bursty FSEvents)
+    private var lastFullRescanDate: Date?
+    private let fullRescanMinInterval: TimeInterval = 1.0
+
     // FSEvents kernel-side coalescing latency
     private static let latency: CFTimeInterval = 0.5
 
@@ -124,7 +128,7 @@ final class FSEventsDirectoryWatcher: @unchecked Sendable {
     /// Coalesces rapid bursts: cancels previous work item, schedules new one after throttleDelay.
     private func scheduleHandleEvents(paths: [String], flags: [FSEventStreamEventFlags]) {
         pendingWork?.cancel()
-        log.debug("[FSEvents] scheduleHandleEvents: \(paths.count) paths for '\(watchedPath)': \(paths)")
+        //log.debug("[FSEvents] scheduleHandleEvents: \(paths.count) paths for '\(watchedPath)': \(paths)")
         let work = DispatchWorkItem { [weak self] in
             self?.handleEvents(paths: paths, flags: flags)
         }
@@ -170,9 +174,18 @@ final class FSEventsDirectoryWatcher: @unchecked Sendable {
         // When dir-level event fires for watched dir itself, trigger full rescan.
         // Dir-level FSEvents cannot tell us which files were added/removed —
         // only that "something changed" in the directory.
-        log.debug("[FSEvents] handleEvents: watchedDirChanged=\(watchedDirChanged) directChildren=\(directChildren.count) childCountUpdates=\(childCountUpdates.count)")
+        //log.debug("[FSEvents] handleEvents: watchedDirChanged=\(watchedDirChanged) directChildren=\(directChildren.count) childCountUpdates=\(childCountUpdates.count)")
         if watchedDirChanged && directChildren.isEmpty {
-            log.info("[FSEvents] watched dir event → full rescan for '\(watched)'")
+            let now = Date()
+            if let last = lastFullRescanDate,
+               now.timeIntervalSince(last) < fullRescanMinInterval {
+                log.debug("[FSEvents] full rescan suppressed (debounced) for '\(watched)'")
+                return
+            }
+
+            lastFullRescanDate = now
+            log.info("[FSEvents] watched dir event → full rescan for '\(watched)' (debounced)")
+
             let patch = DirectoryPatch(
                 childCountUpdates: childCountUpdates,
                 addedOrModified: [],
@@ -184,7 +197,7 @@ final class FSEventsDirectoryWatcher: @unchecked Sendable {
             return
         }
         guard !directChildren.isEmpty || !childCountUpdates.isEmpty else { return }
-        
+
         var added: [CustomFile] = []
         var removed: [String] = []