#5 fix camera capture preview after shooting

- Dismiss the camera fullScreenCover through the SwiftUI binding
  synchronously in the picker delegate before background file
  preparation, so UIImagePickerController no longer dismisses itself
  and desynchronizes the presentation state that the preview sheet
  waits on.
- Keep the archive-sync suspension reserved across the dismissal and
  surface an explicit error when the captured file fails to prepare.
- Add verify.sh invariants for the camera dismissal flow.

Scripts/verify.sh

@@ -336,6 +336,14 @@ grep -q 'let items = pickedMediaItems' Sources/Shared/UI/ChatView.swift || {
   echo "Gallery staging must run on picker dismissal only"
   exit 1
 }
+grep -q 'onDismissRequest' Sources/Shared/UI/SystemPhotoCameraView.swift || {
+  echo "The camera picker must request dismissal before background preparation"
+  exit 1
+}
+grep -q 'onDismissRequest' Sources/Shared/UI/ChatView.swift || {
+  echo "The camera cover must dismiss through the SwiftUI binding"
+  exit 1
+}
 grep -q 'ArchiveSyncCursorPolicy.requestPosition' Sources/Shared/XMPP/XMPPService.swift || {
   echo "MAM reconnects must prefer the durable archive UID over timestamps"
   exit 1

Sources/Shared/UI/ChatView.swift

@@ -254,13 +254,23 @@ struct ChatView: View {
                 }
             ) {
                 SystemPhotoCameraView(
-                    onMedia: { result in
+                    onDismissRequest: {
+                        // Runs synchronously in the picker delegate while the
+                        // camera is still presented: dismiss through the
+                        // binding so SwiftUI owns the transition, and reserve
+                        // the archive-sync suspension across the dismissal
+                        // while the file is prepared in the background.
                         showingPhotoCamera = false
+                        photoCameraIsPreparingResult = true
+                    },
+                    onMedia: { result in
                         switch result {
                         case .success(let media):
                             photoCameraIsPreparingResult = true
                             Task { await stageCapturedMedia(media) }
                         case .failure(let error):
+                            photoCameraIsPreparingResult = false
+                            releaseArchiveSyncAfterCapture()
                             model.errorMessage = error.localizedDescription
                         }
                     },
@@ -1227,11 +1237,12 @@ struct ChatView: View {
         }
     }
 
+    @discardableResult
     private func stageImportedFiles(
         _ urls: [URL],
         preferredKind: ChatMessage.Kind? = nil
-    ) async {
-        guard !urls.isEmpty else { return }
+    ) async -> Bool {
+        guard !urls.isEmpty else { return false }
         isPreparingAttachments = true
         defer { isPreparingAttachments = false }
         let prepared = await model.prepareAttachmentDrafts(
@@ -1239,10 +1250,11 @@ struct ChatView: View {
             preferredKind: preferredKind,
             for: conversation.jid
         )
-        guard !prepared.isEmpty else { return }
+        guard !prepared.isEmpty else { return false }
         model.discardAttachmentDrafts(attachmentDrafts)
         attachmentDrafts = prepared
         presentAttachmentPreviewAfterPickerDismissal()
+        return true
     }
 
     private func stageCapturedMedia(_ media: CapturedCameraMedia) async {
@@ -1251,7 +1263,10 @@ struct ChatView: View {
             photoCameraIsPreparingResult = false
             releaseArchiveSyncAfterCapture()
         }
-        await stageImportedFiles([media.url], preferredKind: media.kind)
+        let staged = await stageImportedFiles([media.url], preferredKind: media.kind)
+        if !staged, model.errorMessage == nil {
+            model.errorMessage = "Камера вернула файл, который не удалось подготовить к отправке."
+        }
     }
 
     private func presentCamera() {

Sources/Shared/UI/SystemPhotoCameraView.swift

@@ -12,6 +12,13 @@ import UIKit
 
 @MainActor
 struct SystemPhotoCameraView: UIViewControllerRepresentable {
+    /// Called synchronously on the main thread inside
+    /// `didFinishPickingMediaWithInfo`, before any background preparation.
+    /// The host must flip its `isPresented` binding here so SwiftUI drives
+    /// the dismissal; letting UIImagePickerController dismiss itself leaves
+    /// the fullScreenCover state desynchronized and breaks the follow-up
+    /// preview presentation.
+    let onDismissRequest: () -> Void
     let onMedia: (Result<CapturedCameraMedia, Error>) -> Void
     let onCancel: () -> Void
 
@@ -20,7 +27,11 @@ struct SystemPhotoCameraView: UIViewControllerRepresentable {
     }
 
     func makeCoordinator() -> Coordinator {
-        Coordinator(onMedia: onMedia, onCancel: onCancel)
+        Coordinator(
+            onDismissRequest: onDismissRequest,
+            onMedia: onMedia,
+            onCancel: onCancel
+        )
     }
 
     func makeUIViewController(context: Context) -> UIImagePickerController {
@@ -42,14 +53,17 @@ struct SystemPhotoCameraView: UIViewControllerRepresentable {
     ) {}
 
     final class Coordinator: NSObject, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
+        private let onDismissRequest: () -> Void
         private let onMedia: (Result<CapturedCameraMedia, Error>) -> Void
         private let onCancel: () -> Void
         private var completed = false
 
         init(
+            onDismissRequest: @escaping () -> Void,
             onMedia: @escaping (Result<CapturedCameraMedia, Error>) -> Void,
             onCancel: @escaping () -> Void
         ) {
+            self.onDismissRequest = onDismissRequest
             self.onMedia = onMedia
             self.onCancel = onCancel
         }
@@ -60,6 +74,7 @@ struct SystemPhotoCameraView: UIViewControllerRepresentable {
         ) {
             guard !completed else { return }
             completed = true
+            onDismissRequest()
 
             let mediaType = (info[.mediaType] as? String).flatMap { UTType($0) }
             if mediaType?.conforms(to: .movie) == true,