Keep internal tab drags out of Finder

Resources/Info.plist

@@ -93,27 +93,15 @@
 			</array>
 		</dict>
 	</array>
-	<key>UTExportedTypeDeclarations</key>
+	<key>UTImportedTypeDeclarations</key>
 	<array>
 		<dict>
 			<key>UTTypeIdentifier</key>
 			<string>com.splittabbar.tabtransfer</string>
-			<key>UTTypeDescription</key>
-			<string>Bonsplit Tab Transfer</string>
-			<key>UTTypeConformsTo</key>
-			<array>
-				<string>public.data</string>
-			</array>
 		</dict>
 		<dict>
 			<key>UTTypeIdentifier</key>
 			<string>com.cmux.sidebar-tab-reorder</string>
-			<key>UTTypeDescription</key>
-			<string>cmux Sidebar Tab Reorder</string>
-			<key>UTTypeConformsTo</key>
-			<array>
-				<string>public.data</string>
-			</array>
 		</dict>
 	</array>
 	<key>NSAppTransportSecurity</key>

Sources/ContentView.swift

@@ -82,6 +82,40 @@ func sidebarSelectedWorkspaceForegroundNSColor(opacity: CGFloat) -> NSColor {
     let clampedOpacity = max(0, min(opacity, 1))
     return NSColor.white.withAlphaComponent(clampedOpacity)
 }
+
+#if compiler(>=6.2)
+@available(macOS 26.0, *)
+enum InternalTabDragConfigurationProvider {
+    // These drags only make sense inside cmux. Outside the app, Finder should
+    // reject them instead of materializing placeholder files from the payload.
+    static let value = DragConfiguration(
+        operationsWithinApp: .init(allowCopy: false, allowMove: true, allowDelete: false),
+        operationsOutsideApp: .init(allowCopy: false, allowMove: false, allowDelete: false)
+    )
+}
+#endif
+
+private struct InternalTabDragConfigurationModifier: ViewModifier {
+    @ViewBuilder
+    func body(content: Content) -> some View {
+        #if compiler(>=6.2)
+        if #available(macOS 26.0, *) {
+            content.dragConfiguration(InternalTabDragConfigurationProvider.value)
+        } else {
+            content
+        }
+        #else
+        content
+        #endif
+    }
+}
+
+extension View {
+    func internalOnlyTabDrag() -> some View {
+        modifier(InternalTabDragConfigurationModifier())
+    }
+}
+
 struct ShortcutHintPillBackground: View {
     var emphasis: Double = 1.0
 
@@ -9662,6 +9696,7 @@ private struct TabItemView: View {
             dropIndicator = nil
             return SidebarTabDragPayload.provider(for: tab.id)
         }
+        .internalOnlyTabDrag()
         .onDrop(of: SidebarTabDragPayload.dropContentTypes, delegate: SidebarTabDropDelegate(
             targetTabId: tab.id,
             tabManager: tabManager,

Sources/WorkspaceContentView.swift

@@ -106,6 +106,7 @@ struct WorkspaceContentView: View {
                     workspace.bonsplitController.focusPane(paneId)
                 }
         }
+        .internalOnlyTabDrag()
         // Split zoom swaps Bonsplit between the full split tree and a single pane view.
         // Recreate the Bonsplit subtree on zoom enter/exit so stale pre-zoom pane chrome
         // cannot remain stacked above portal-hosted browser content.