iOS transfers: 'Uploading...' then 'Uploaded' notification, and count share uploads

The Share Extension's session had no delegate, so a fast upload finished
unseen and the invalidated session was discarded before the app could hear of
it - no summary notification. Results are now handled by a shared delegate in
whichever process is alive, started/finished notifications replace each
other in place, and the app refreshes the folder the extension uploaded to.

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

ios/Shared/TransferNotifications.swift

@@ -0,0 +1,80 @@
+import Foundation
+import UserNotifications
+
+/// The local notifications for an upload/download batch - one "Uploading 3
+/// files…" when it starts, replaced in place by "Uploaded 3 files" when it
+/// ends (both use the batch's id as the request identifier, so the second
+/// *replaces* the first instead of stacking). Posted from whichever process
+/// sees the event - the app, or the Share Extension while it's still alive.
+/// iOS can't update a notification with live byte progress from a background
+/// session, so start/finish is as much as a notification can say.
+/// Compiled into both targets.
+enum TransferNotifications {
+  static func started(kind: TransferTaskInfo.Kind, batch: String, count: Int) {
+    let verb = kind == .upload ? "Uploading" : "Downloading"
+    post(id: batch, body: "\(verb) \(files(count))…", sound: false)
+  }
+
+  static func finished(_ batch: TransferBatch, id: String) {
+    let verb = batch.kind == .upload ? "upload" : "download"
+    let past = batch.kind == .upload ? "Uploaded" : "Downloaded"
+    let body: String
+    if batch.failed == 0 {
+      body = "\(past) \(files(batch.succeeded))"
+    } else if batch.succeeded == 0 {
+      body = "Couldn't \(verb) \(files(batch.failed))"
+    } else {
+      body = "\(past) \(files(batch.succeeded)), \(batch.failed) failed"
+    }
+    post(id: id, body: body, sound: true)
+  }
+
+  static func files(_ count: Int) -> String {
+    count == 1 ? "1 file" : "\(count) files"
+  }
+
+  private static func post(id: String, body: String, sound: Bool) {
+    let content = UNMutableNotificationContent()
+    content.title = "Noo"
+    content.body = body
+    if sound { content.sound = .default }
+    UNUserNotificationCenter.current().add(
+      UNNotificationRequest(identifier: "transfer.\(id)", content: content, trigger: nil))
+  }
+}
+
+/// Counting one finished upload task - shared so the result is handled the
+/// same way whether the Share Extension (still alive) or the app (relaunched
+/// later) receives it.
+enum UploadResults {
+  /// Deletes the task's staged copy, records its outcome, and - if it was the
+  /// last file of its batch - posts the summary notification and returns the
+  /// finished batch.
+  static func handle(_ task: URLSessionTask, error: Error?) -> (info: TransferTaskInfo, batch: TransferBatch?)? {
+    guard let info = task.taskDescription
+      .flatMap({ $0.data(using: .utf8) })
+      .flatMap({ try? JSONDecoder().decode(TransferTaskInfo.self, from: $0) }),
+      info.kind == .upload
+    else { return nil }
+    if let staged = info.stagedPath { try? FileManager.default.removeItem(atPath: staged) }
+    let status = (task.response as? HTTPURLResponse)?.statusCode ?? 0
+    let ok = error == nil && (200..<300).contains(status)
+    let batch = TransferBatchStore.record(info, success: ok)
+    if let batch { TransferNotifications.finished(batch, id: info.batch) }
+    return (info, batch)
+  }
+}
+
+/// Delegate for the Share Extension's upload session while the extension is
+/// still alive: files that finish before it closes are counted here, the
+/// rest by the app (`TransferManager`) once the system relaunches it.
+final class ShareUploadDelegate: NSObject, URLSessionTaskDelegate {
+  func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
+    guard let result = UploadResults.handle(task, error: error) else { return }
+    // The app wasn't running to hear about this, so leave a note for it to
+    // refresh that folder next time it's active.
+    if let batch = result.batch, batch.succeeded > 0, let folder = batch.remoteFolder {
+      TransferBatchStore.noteFinishedUpload(folder: folder)
+    }
+  }
+}