add sidebar multi-selection with shift-click, cmd-click, and batch delete

src/SidebarView.swift

@@ -2,6 +2,8 @@ import SwiftUI
 
 struct SidebarView: View {
     @ObservedObject var state: AppState
+    @State private var selection: Set<UUID> = []
+    @State private var lastClickedID: UUID?
 
     private let dateFormatter: DateFormatter = {
         let f = DateFormatter()
@@ -38,46 +40,106 @@ struct SidebarView: View {
                     Spacer()
                 }
             } else {
-                List(state.noteList) { note in
+                ScrollView {
+                    LazyVStack(spacing: 0) {
+                        ForEach(Array(state.noteList.enumerated()), id: \.element.id) { index, note in
                             NoteRow(
                                 note: note,
-                        isSelected: note.id == state.currentNoteID,
+                                isActive: note.id == state.currentNoteID,
+                                isSelected: selection.contains(note.id),
                                 dateFormatter: dateFormatter
                             )
                             .contentShape(Rectangle())
-                    .onTapGesture { state.loadNote(note.id) }
+                            .onTapGesture(count: 2) {
+                                selection = [note.id]
+                                lastClickedID = note.id
+                                state.loadNote(note.id)
+                            }
+                            .onTapGesture(count: 1) {
+                                handleClick(note: note, index: index, modifiers: currentModifiers())
+                            }
                             .contextMenu {
+                                if selection.count > 1 && selection.contains(note.id) {
+                                    Button("Delete \(selection.count) Notes") {
+                                        state.deleteNotes(selection)
+                                        selection.removeAll()
+                                        lastClickedID = nil
+                                    }
+                                } else {
                                     Button("Delete") { state.deleteNote(note.id) }
                                 }
-                    .listRowBackground(
-                        note.id == state.currentNoteID
-                            ? Color(ns: Theme.current.surface1)
-                            : Color.clear
-                    )
                             }
-                .listStyle(.plain)
+                        }
+                    }
+                }
+                .onDeleteCommand {
+                    guard !selection.isEmpty else { return }
+                    state.deleteNotes(selection)
+                    selection.removeAll()
+                    lastClickedID = nil
+                }
             }
         }
         .background(Color(ns: Theme.current.mantle))
         .onAppear { state.refreshNoteList() }
     }
+
+    private func handleClick(note: NoteInfo, index: Int, modifiers: EventModifiers) {
+        if modifiers.contains(.command) {
+            if selection.contains(note.id) {
+                selection.remove(note.id)
+            } else {
+                selection.insert(note.id)
+            }
+            lastClickedID = note.id
+        } else if modifiers.contains(.shift), let lastID = lastClickedID {
+            if let lastIndex = state.noteList.firstIndex(where: { $0.id == lastID }) {
+                let range = min(lastIndex, index)...max(lastIndex, index)
+                for i in range {
+                    selection.insert(state.noteList[i].id)
+                }
+            }
+        } else {
+            selection = [note.id]
+            lastClickedID = note.id
+            state.loadNote(note.id)
+        }
+    }
+
+    private func currentModifiers() -> EventModifiers {
+        let flags = NSEvent.modifierFlags
+        var mods: EventModifiers = []
+        if flags.contains(.command) { mods.insert(.command) }
+        if flags.contains(.shift) { mods.insert(.shift) }
+        return mods
+    }
 }
 
 struct NoteRow: View {
     let note: NoteInfo
+    let isActive: Bool
     let isSelected: Bool
     let dateFormatter: DateFormatter
 
     var body: some View {
         VStack(alignment: .leading, spacing: 2) {
             Text(note.title)
-                .font(.system(size: 13, weight: isSelected ? .semibold : .regular))
+                .font(.system(size: 13, weight: isActive ? .semibold : .regular))
                 .foregroundColor(Color(ns: Theme.current.text))
                 .lineLimit(1)
             Text(dateFormatter.string(from: note.lastModified))
                 .font(.system(size: 11))
                 .foregroundColor(Color(ns: Theme.current.subtext0))
         }
-        .padding(.vertical, 2)
+        .frame(maxWidth: .infinity, alignment: .leading)
+        .padding(.vertical, 4)
+        .padding(.horizontal, 12)
+        .background(
+            isActive
+                ? Color(ns: Theme.current.surface1)
+                : isSelected
+                    ? Color(ns: Theme.current.surface0)
+                    : Color.clear
+        )
     }
 }