Share Extension: account picker first, hidden folders follow the app's filter + unlock

The app now publishes every uploadable account, the active one, the three
lock settings and each account's own hidden-files filter (ShareAccountSync).
The sheet lists accounts first when there are several, asks for unlock to use
a non-active account (login lock + account-switching lock), and shows hidden
folders per the account's app setting behind the hidden-files unlock.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ios/ShareExtension/SharePickerView.swift

@@ -1,10 +1,11 @@
 import SwiftUI
 
-/// State behind the share sheet's folder picker.
+/// State behind the share sheet's account and folder pickers.
 @MainActor
 final class ShareModel: ObservableObject {
   enum Stage: Equatable {
     case preparing
+    case chooseAccount
     case picking
     case uploading
     case noAccount
@@ -17,18 +18,30 @@ final class ShareModel: ObservableObject {
   @Published var folders: [DavFolder] = []
   @Published var isLoadingFolders = false
   @Published var folderError: String?
+  /// A short explanation shown under the list - e.g. hidden folders stayed
+  /// hidden because the unlock was cancelled.
+  @Published var notice: String?
+  @Published private(set) var selected: SharedAccount?
 
-  let account: SharedAccount?
+  let shared: SharedAccounts?
+
+  /// One successful unlock covers every gate for the rest of this sheet.
+  private var unlocked = false
+  private var hidden: HiddenFilter = .hide
 
   /// Set by the view controller: what each button actually does.
   var onUpload: () -> Void = {}
   var onSaveForLater: () -> Void = {}
   var onCancel: () -> Void = {}
 
-  init(account: SharedAccount?) {
-    self.account = account
+  init(shared: SharedAccounts?) {
+    self.shared = shared
   }
 
+  var accounts: [SharedAccount] { shared?.accounts ?? [] }
+  var canChangeAccount: Bool { accounts.count > 1 }
+  var activeAccountId: String? { shared?.active?.id }
+
   var currentFolderName: String {
     path == "/" ? "All files" : (path as NSString).lastPathComponent
   }
@@ -37,14 +50,66 @@ final class ShareModel: ObservableObject {
     items.count == 1 ? "1 file" : "\(items.count) files"
   }
 
+  /// With several accounts the list comes first; with one it goes straight
+  /// to its folders.
+  func start() async {
+    guard let shared, let first = shared.accounts.first else {
+      stage = .noAccount
+      return
+    }
+    if shared.accounts.count > 1 {
+      stage = .chooseAccount
+    } else {
+      await select(first)
+    }
+  }
+
+  func showAccounts() {
+    notice = nil
+    stage = .chooseAccount
+  }
+
+  /// Uploading to an account other than the one the app is on is "switching"
+  /// in the app's terms, so it asks for the same unlock when the app does.
+  /// Hidden folders follow the account's own app setting, behind the app's
+  /// "lock hidden files" unlock.
+  func select(_ account: SharedAccount) async {
+    guard let shared else { return }
+    notice = nil
+    if account.id != shared.active?.id, shared.needsUnlockToSwitchAccount {
+      guard await unlock("Unlock to upload to \(account.displayName)") else {
+        notice = "Unlock to upload to a different account."
+        stage = .chooseAccount
+        return
+      }
+    }
+    selected = account
+    hidden = HiddenFilter(raw: account.hiddenFilter)
+    if hidden != .hide, shared.needsUnlockForHidden {
+      if await !unlock("Unlock to show hidden folders") {
+        hidden = .hide
+        notice = "Hidden folders are locked, so they're not shown."
+      }
+    }
+    stage = .picking
+    await open("/")
+  }
+
+  private func unlock(_ reason: String) async -> Bool {
+    if unlocked { return true }
+    let ok = await DeviceAuth.authenticate(reason: reason)
+    if ok { unlocked = true }
+    return ok
+  }
+
   func open(_ path: String) async {
-    guard let account else { return }
+    guard let account = selected else { return }
     self.path = path
     isLoadingFolders = true
     folderError = nil
     defer { isLoadingFolders = false }
     do {
-      folders = try await DavClient.listFolders(account: account, path: path)
+      folders = try await DavClient.listFolders(account: account, path: path, hidden: hidden)
     } catch {
       folders = []
       folderError = error.localizedDescription
@@ -107,19 +172,48 @@ struct SharePickerView: View {
       centered {
         Text(message).multilineTextAlignment(.center).foregroundColor(.secondary).padding()
       }
+    case .chooseAccount:
+      accountList
     case .picking:
       folderList
     }
   }
 
+  private var accountList: some View {
+    List {
+      Section(
+        header: Text("Upload \(model.fileCountText) to which account?"),
+        footer: model.notice.map { Text($0) }
+      ) {
+        ForEach(model.accounts) { account in
+          Button {
+            Task { await model.select(account) }
+          } label: {
+            HStack {
+              Label(account.displayName, systemImage: "person.crop.circle")
+              Spacer()
+              if account.id == model.activeAccountId {
+                Text("Active").font(.caption).foregroundColor(.secondary)
+              }
+            }
+          }
+        }
+      }
+    }
+    .listStyle(.insetGrouped)
+  }
+
   private var folderList: some View {
     List {
-      Section(header: Text(model.account?.displayName ?? "")) {
+      Section(
+        header: accountHeader,
+        footer: model.notice.map { Text($0) }
+      ) {
         if model.path != "/" {
           Button {
             Task { await model.openParent() }
           } label: {
-            Label("Up to \((model.path as NSString).deletingLastPathComponent == "/" ? "All files" : ((model.path as NSString).deletingLastPathComponent as NSString).lastPathComponent)", systemImage: "arrow.turn.left.up")
+            Label("Up to \(parentName)", systemImage: "arrow.turn.left.up")
           }
         }
         if model.isLoadingFolders {
@@ -142,6 +236,22 @@ struct SharePickerView: View {
     .listStyle(.insetGrouped)
   }
 
+  private var accountHeader: some View {
+    HStack {
+      Text(model.selected?.displayName ?? "")
+      Spacer()
+      if model.canChangeAccount {
+        Button("Change account") { model.showAccounts() }
+          .font(.caption)
+      }
+    }
+  }
+
+  private var parentName: String {
+    let parent = (model.path as NSString).deletingLastPathComponent
+    return parent.isEmpty || parent == "/" ? "All files" : (parent as NSString).lastPathComponent
+  }
+
   private var footer: some View {
     VStack(spacing: 8) {
       if model.stage == .picking {
@@ -154,7 +264,7 @@ struct SharePickerView: View {
         .buttonStyle(.borderedProminent)
         .disabled(model.isLoadingFolders)
       }
-      if model.stage == .picking || model.stage == .noAccount {
+      if model.stage == .picking || model.stage == .chooseAccount || model.stage == .noAccount {
         Button("Choose a folder later in Noo", action: model.onSaveForLater)
           .font(.subheadline)
       }