migrate persistence from JSON to SwiftData

Models:
- Convert Conversation and ChatMessage to SwiftData @Model classes with
  a
  one-to-many relationship and cascade delete.
- Rename ChatMessage.id to clientID and drop Conversation.id in favor of
  jid
  (the string id would clash with PersistentIdentifier).
- Keep MessageReaction as a Codable value stored in an array attribute.

Persistence:
- Add ArchiveStore, a per-account ModelContainer/ModelContext that
  replaces
  the JSON ChatArchive with load/save/erase.
- Add ArchiveMetadataRecord for the durable MAM checkpoints, cursor,
  locally
  deleted message IDs and roster contact JIDs.
- Add LegacyArchiveImporter to import the old JSON snapshot once and
  delete
  the file afterwards, preserving existing history.

AppModel:
- Replace ChatArchive with ArchiveStore and persist via context.save();
  insert new models and delete the replaced object on upsert merges so
  SwiftData never keeps an orphaned duplicate.

Tests:
- Replace ChatArchiveTests with ArchiveStoreTests (store round-trip and
  legacy import) and drop the now-obsolete Codable round-trip
  assertions.

Sources/Shared/UI/CallView.swift

@@ -8,7 +8,7 @@ struct CallView: View {
     let call: CallSnapshot
 
     private var conversation: Conversation {
-        model.conversations.first(where: { $0.id == call.peerJID.lowercased() })
+        model.conversations.first(where: { $0.jid == call.peerJID.lowercased() })
             ?? Conversation(jid: call.peerJID, displayName: model.displayName(for: call.peerJID))
     }
 

Sources/Shared/UI/ChatView.swift

@@ -15,7 +15,7 @@ private enum EmojiPickerPresentation: Identifiable {
 
     var id: String {
         switch self {
-        case .reaction(let message): return "reaction-\(message.id)"
+        case .reaction(let message): return "reaction-\(message.clientID)"
         case .composer: return "composer"
         }
     }
@@ -254,7 +254,7 @@ struct ChatView: View {
         .overlay {
             replyThreadOverlay
         }
-        .onChange(of: conversation.id) { _, _ in
+        .onChange(of: conversation.jid) { _, _ in
             hasCompletedInitialScroll = false
             isNearTimelineBottom = true
             historyLoadAnchorID = nil
@@ -284,7 +284,7 @@ struct ChatView: View {
     @ViewBuilder
     private var replyThreadOverlay: some View {
         if let selection = replyThreadSelection,
-           let root = model.message(withID: selection.rootID, in: conversation.id) {
+           let root = model.message(withID: selection.rootID, in: conversation.jid) {
             ReplyThreadOverlay(
                 model: model,
                 rootMessage: root,
@@ -332,7 +332,7 @@ struct ChatView: View {
     }
 
     private var selectedTimelineMessages: [ChatMessage] {
-        model.selectedMessages.filter { selectedMessageIDs.contains($0.id) }
+        model.selectedMessages.filter { selectedMessageIDs.contains($0.clientID) }
     }
 
     private var isSelectingMessages: Bool {
@@ -396,7 +396,7 @@ struct ChatView: View {
                                         model: model,
                                         message: message,
                                         isSelectionMode: isSelectingMessages,
-                                        isSelected: selectedMessageIDs.contains(message.id),
+                                        isSelected: selectedMessageIDs.contains(message.clientID),
                                         onAttachmentTap: {
                                             Task { await model.previewAttachment(message) }
                                         },
@@ -417,7 +417,7 @@ struct ChatView: View {
                                         onReplyTap: { targetID in
                                             presentReplyThread(
                                                 rootID: targetID,
-                                                selectedReplyID: message.id
+                                                selectedReplyID: message.clientID
                                             )
                                         },
                                         onReact: { emoji in
@@ -427,7 +427,7 @@ struct ChatView: View {
                                             emojiPickerPresentation = .reaction(message)
                                         }
                                     )
-                                    .id(message.id)
+                                    .id(message.clientID)
                                 }
                             }
                         }
@@ -435,7 +435,7 @@ struct ChatView: View {
 
                         timelineBottomSentinel
 #if os(iOS)
-                        ChatScrollMetricsObserver(identity: conversation.id) { isNearBottom in
+                        ChatScrollMetricsObserver(identity: conversation.jid) { isNearBottom in
                             guard isNearTimelineBottom != isNearBottom else { return }
                             isNearTimelineBottom = isNearBottom
                         }
@@ -766,13 +766,13 @@ struct ChatView: View {
 
     private var editingMessage: ChatMessage? {
         guard let editingMessageID else { return nil }
-        return model.selectedMessages.first { $0.id == editingMessageID }
+        return model.selectedMessages.first { $0.clientID == editingMessageID }
     }
 
     private var replyingToMessage: ChatMessage? {
         guard let replyingToMessageID else { return nil }
         return model.selectedMessages.first {
-            $0.id == replyingToMessageID && $0.canBeRepliedTo
+            $0.clientID == replyingToMessageID && $0.canBeRepliedTo
         }
     }
 
@@ -790,7 +790,7 @@ struct ChatView: View {
     }
 
     private var liveConversation: Conversation {
-        model.conversations.first(where: { $0.id == conversation.id }) ?? conversation
+        model.conversations.first(where: { $0.jid == conversation.jid }) ?? conversation
     }
 
     private var chatNavigationTitle: some View {
@@ -1212,7 +1212,7 @@ struct ChatView: View {
     }
 
     private func presentReplyThread(rootID: String, selectedReplyID: String) {
-        guard model.message(withID: rootID, in: conversation.id) != nil else {
+        guard model.message(withID: rootID, in: conversation.jid) != nil else {
             model.errorMessage = "Исходное сообщение ещё не загружено в локальную историю."
             return
         }
@@ -1234,7 +1234,7 @@ struct ChatView: View {
         for root: ChatMessage,
         selectedReplyID: String
     ) -> [ChatMessage] {
-        var sourceIdentifiers: Set<String> = [root.id]
+        var sourceIdentifiers: Set<String> = [root.clientID]
         if let stanzaID = root.stanzaID { sourceIdentifiers.insert(stanzaID) }
         if let replyIdentifier = root.replyIdentifier {
             sourceIdentifiers.insert(replyIdentifier)
@@ -1244,12 +1244,12 @@ struct ChatView: View {
             guard let replyToID = candidate.replyToID else { return false }
             return sourceIdentifiers.contains(replyToID)
         }
-        if !replies.contains(where: { $0.id == selectedReplyID }),
-           let selected = model.message(withID: selectedReplyID, in: conversation.id) {
+        if !replies.contains(where: { $0.clientID == selectedReplyID }),
+           let selected = model.message(withID: selectedReplyID, in: conversation.jid) {
             replies.append(selected)
         }
         return replies.sorted { lhs, rhs in
-            if lhs.timestamp == rhs.timestamp { return lhs.id < rhs.id }
+            if lhs.timestamp == rhs.timestamp { return lhs.clientID < rhs.clientID }
             return lhs.timestamp < rhs.timestamp
         }
     }
@@ -1407,7 +1407,7 @@ struct ChatView: View {
         guard message.canBeEdited else { return }
         cancelComposerRecording(feedback: false)
         replyingToMessageID = nil
-        editingMessageID = message.id
+        editingMessageID = message.clientID
         draft = message.body
         isComposerFocused = true
     }
@@ -1429,14 +1429,14 @@ struct ChatView: View {
         dismissKeyboard()
         if editingMessageID != nil { cancelEditing() }
         cancelReplying()
-        selectedMessageIDs.insert(message.id)
+        selectedMessageIDs.insert(message.clientID)
     }
 
     private func toggleMessageSelection(_ message: ChatMessage) {
-        if selectedMessageIDs.contains(message.id) {
-            selectedMessageIDs.remove(message.id)
+        if selectedMessageIDs.contains(message.clientID) {
+            selectedMessageIDs.remove(message.clientID)
         } else {
-            selectedMessageIDs.insert(message.id)
+            selectedMessageIDs.insert(message.clientID)
         }
     }
 
@@ -1457,7 +1457,7 @@ struct ChatView: View {
             editingMessageID = nil
             draft = ""
         }
-        replyingToMessageID = message.id
+        replyingToMessageID = message.clientID
         isComposerFocused = true
     }
 
@@ -1526,7 +1526,7 @@ struct ChatView: View {
     }
 
     private func perform(_ action: MessageDestructiveAction) {
-        let ids = Set(action.messages.map(\.id))
+        let ids = Set(action.messages.map(\.clientID))
         if let editingMessageID, ids.contains(editingMessageID) {
             cancelEditing()
         }
@@ -1536,11 +1536,11 @@ struct ChatView: View {
         selectedMessageIDs.subtract(ids)
         switch action.kind {
         case .localDelete:
-            model.deleteMessagesLocally(ids: ids, in: conversation.id)
+            model.deleteMessagesLocally(ids: ids, in: conversation.jid)
         case .retract:
             Task {
                 for message in action.messages where message.canBeRetracted {
-                    await model.retractMessage(id: message.id)
+                    await model.retractMessage(id: message.clientID)
                 }
             }
         }
@@ -2161,7 +2161,7 @@ private struct MessageDestructiveAction: Identifiable {
     let messages: [ChatMessage]
 
     var id: String {
-        let messageIDs = messages.map(\.id).sorted().joined(separator: "-")
+        let messageIDs = messages.map(\.clientID).sorted().joined(separator: "-")
         return "\(kind == .localDelete ? "local" : "retract")-\(messageIDs)"
     }
 

Sources/Shared/UI/Components/AudioMessagePlayer.swift

@@ -129,7 +129,7 @@ struct AudioMessagePlayer: View {
     }
 
     private var isCurrent: Bool {
-        playback.currentMessageID == message.id
+        playback.currentMessageID == message.clientID
     }
 
     private var isPlaying: Bool {
@@ -194,7 +194,7 @@ struct AudioMessagePlayer: View {
                     return
                 }
                 playback.toggle(
-                    messageID: message.id,
+                    messageID: message.clientID,
                     url: downloadedURL,
                     durationHint: message.duration,
                     isVoice: message.kind == .voice
@@ -203,7 +203,7 @@ struct AudioMessagePlayer: View {
             return
         }
         playback.toggle(
-            messageID: message.id,
+            messageID: message.clientID,
             url: localURL,
             durationHint: message.duration,
             isVoice: message.kind == .voice
@@ -213,7 +213,7 @@ struct AudioMessagePlayer: View {
     private func seek(_ fraction: Double) {
         guard let localURL else { return }
         playback.seek(
-            messageID: message.id,
+            messageID: message.clientID,
             url: localURL,
             durationHint: message.duration,
             isVoice: message.kind == .voice,

Sources/Shared/UI/Components/PhotoAttachmentPreview.swift

@@ -124,7 +124,7 @@ struct PhotoAttachmentPreview: View {
     private func openViewer() {
         Task {
             await model.presentMediaViewer(message)
-            if model.mediaViewerItem?.id != message.id,
+            if model.mediaViewerItem?.id != message.clientID,
                message.remoteAttachmentURL == nil {
                 onFallbackTap()
             }

Sources/Shared/UI/Components/ReplyThreadOverlay.swift

@@ -112,10 +112,10 @@ struct ReplyThreadOverlay: View {
                     model: model,
                     message: reply,
                     maximumBubbleWidth: maximumBubbleWidth,
-                    isSelected: reply.id == selectedReplyID,
-                    showsDeliveryStatus: reply.id == selectedReplyID
+                    isSelected: reply.clientID == selectedReplyID,
+                    showsDeliveryStatus: reply.clientID == selectedReplyID
                 )
-                .id(reply.id)
+                .id(reply.clientID)
             }
         }
         .padding(.leading, showsBracket && bracketOnLeadingEdge ? 43 : 0)

Sources/Shared/UI/Components/VideoAttachmentPreview.swift

@@ -142,7 +142,7 @@ struct VideoAttachmentPreview: View {
     private func openViewer() {
         Task {
             await model.presentMediaViewer(message)
-            if model.mediaViewerItem?.id != message.id,
+            if model.mediaViewerItem?.id != message.clientID,
                message.remoteAttachmentURL == nil {
                 onFallbackTap()
             }

Sources/Shared/UI/Components/VideoNotePreview.swift

@@ -82,7 +82,7 @@ struct VideoNotePreview: View {
         }
         .onReceive(NotificationCenter.default.publisher(for: .lumaExclusiveMediaPlayback)) { notification in
             guard let activeID = notification.object as? String,
-                  activeID != message.id else { return }
+                  activeID != message.clientID else { return }
             player?.pause()
             isPlaying = false
         }
@@ -146,7 +146,7 @@ struct VideoNotePreview: View {
             model.audioPlayback.stop()
             NotificationCenter.default.post(
                 name: .lumaExclusiveMediaPlayback,
-                object: message.id
+                object: message.clientID
             )
             player.play()
         }

Sources/Shared/UI/GroupInfoView.swift

@@ -92,7 +92,7 @@ struct GroupInfoView: View {
     }
 
     private var liveConversation: Conversation {
-        model.conversations.first(where: { $0.id == conversation.id }) ?? conversation
+        model.conversations.first(where: { $0.jid == conversation.jid }) ?? conversation
     }
 
     private var parsedInvitees: [String] {

Sources/Shared/UI/MainChatView.swift

@@ -28,7 +28,7 @@ struct MainChatView: View {
 
     private var filteredRosterContacts: [Conversation] {
         model.conversations
-            .filter { !$0.isGroup && model.rosterContactJIDs.contains($0.id) }
+            .filter { !$0.isGroup && model.rosterContactJIDs.contains($0.jid) }
             .filter { searchText.isEmpty || matchesSearch($0) }
             .sorted(by: contactSort)
     }
@@ -91,7 +91,7 @@ struct MainChatView: View {
         } detail: {
             if let conversation = model.selectedConversation {
                 ChatView(model: model, conversation: conversation)
-                    .id(conversation.id)
+                    .id(conversation.jid)
             } else {
                 WelcomeDetailView()
             }
@@ -120,7 +120,7 @@ struct MainChatView: View {
                     imageData: model.avatarData(for: conversation.jid),
                     isEncrypted: model.encryptionEnabled(for: conversation.jid)
                 )
-                .tag(conversation.id)
+                .tag(conversation.jid)
                 .listRowInsets(EdgeInsets(top: 6, leading: 12, bottom: 6, trailing: 12))
             }
         }
@@ -149,7 +149,7 @@ struct MainChatView: View {
                             conversation: conversation,
                             imageData: model.avatarData(for: conversation.jid)
                         )
-                        .tag(conversation.id)
+                        .tag(conversation.jid)
                         .listRowInsets(EdgeInsets(top: 7, leading: 12, bottom: 7, trailing: 12))
                     }
                 } header: {
@@ -164,7 +164,7 @@ struct MainChatView: View {
                             conversation: conversation,
                             imageData: model.avatarData(for: conversation.jid)
                         )
-                        .tag(conversation.id)
+                        .tag(conversation.jid)
                         .listRowInsets(EdgeInsets(top: 7, leading: 12, bottom: 7, trailing: 12))
                     }
                 } header: {