feat: meeting data migration and backup

notetaker/Managers/DataMigrationManager.swift

@@ -0,0 +1,54 @@
+// DataMigrationManager.swift
+// Handles data migration between different app versions
+
+import Foundation
+
+/// Manages data migration between different app versions
+class DataMigrationManager {
+    static let shared = DataMigrationManager()
+    
+    private init() {}
+    
+    /// Migrates a meeting from an older version to the current version
+    /// - Parameter meeting: The meeting to migrate
+    /// - Returns: The migrated meeting, or nil if migration failed
+    func migrateMeeting(_ meeting: Meeting) -> Meeting? {
+        // No releases prior to version 1 – any older file is considered unsupported.
+        guard meeting.dataVersion >= 1 else {
+            print("🚫 Cannot migrate meeting \(meeting.id) – unsupported data version \(meeting.dataVersion)")
+            return nil
+        }
+
+        // Future migrations can be added here as `switch` cases.
+        if meeting.dataVersion < Meeting.currentDataVersion {
+            print("⚠️ No migration path for versions \(meeting.dataVersion + 1)...\(Meeting.currentDataVersion)")
+            return nil
+        }
+
+        return meeting
+    }
+    
+    // Future migrateXToVersionY helpers will go here as needed
+    
+    /// Performs a backup of the meetings directory before migration
+    /// - Returns: The backup directory URL, or nil if backup failed
+    func backupMeetingsDirectory() -> URL? {
+        let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
+        let meetingsDirectory = documentsDirectory.appendingPathComponent("Meetings")
+        
+        let formatter = DateFormatter()
+        formatter.dateFormat = "yyyy-MM-dd_HH-mm-ss"
+        let timestamp = formatter.string(from: Date())
+        
+        let backupDirectory = documentsDirectory.appendingPathComponent("Meetings_Backup_\(timestamp)")
+        
+        do {
+            try FileManager.default.copyItem(at: meetingsDirectory, to: backupDirectory)
+            print("✅ Created backup at: \(backupDirectory)")
+            return backupDirectory
+        } catch {
+            print("❌ Failed to create backup: \(error)")
+            return nil
+        }
+    }
+} 

notetaker/Managers/LocalStorageManager.swift

@@ -30,15 +30,19 @@ class LocalStorageManager {
     /// - Returns: True if successful, false otherwise
     func saveMeeting(_ meeting: Meeting) -> Bool {
         let fileURL = meetingsDirectory.appendingPathComponent("\(meeting.id.uuidString).json")
-        
+
         do {
             let encoder = JSONEncoder()
-            encoder.outputFormatting = .prettyPrinted
+            encoder.outputFormatting = [.prettyPrinted]
             encoder.dateEncodingStrategy = .iso8601
-            
+
             let data = try encoder.encode(meeting)
-            try data.write(to: fileURL)
-            
+
+            // Write atomically using a temp file then replace
+            let tmpURL = fileURL.appendingPathExtension("tmp")
+            try data.write(to: tmpURL, options: .atomic)
+            try FileManager.default.replaceItem(at: fileURL, withItemAt: tmpURL, backupItemName: nil, options: [], resultingItemURL: nil)
+
             print("✅ Saved meeting: \(meeting.id)")
             return true
         } catch {
@@ -58,12 +62,41 @@ class LocalStorageManager {
             let decoder = JSONDecoder()
             decoder.dateDecodingStrategy = .iso8601
             
+            var didCreateBackup = false
+            
             let meetings = fileURLs.compactMap { url -> Meeting? in
                 guard let data = try? Data(contentsOf: url),
                       let meeting = try? decoder.decode(Meeting.self, from: data) else {
                     print("⚠️ Failed to decode meeting at: \(url)")
                     return nil
                 }
+                // Forward-compatibility guard – skip if file was written by a newer build
+                if meeting.dataVersion > Meeting.currentDataVersion {
+                    print("🚫 Meeting \(meeting.id) written by newer app version (\(meeting.dataVersion)). Skipping load.")
+                    return nil
+                }
+
+                // Check if migration is needed
+                if meeting.dataVersion < Meeting.currentDataVersion {
+                    // Create backup **once** before we start mutating anything
+                    if !didCreateBackup {
+                        _ = DataMigrationManager.shared.backupMeetingsDirectory()
+                        didCreateBackup = true
+                    }
+
+                    if let migratedMeeting = DataMigrationManager.shared.migrateMeeting(meeting) {
+                        if saveMeeting(migratedMeeting) {
+                            print("✅ Migrated and saved meeting: \(migratedMeeting.id)")
+                            return migratedMeeting
+                        }
+                        print("❌ Failed to save migrated meeting: \(migratedMeeting.id)")
+                    } else {
+                        print("❌ Failed to migrate meeting: \(meeting.id)")
+                    }
+                    // Return original if anything failed
+                    return meeting
+                }
+
                 return meeting
             }
             

notetaker/Models/Meeting.swift

@@ -69,21 +69,30 @@ struct Meeting: Codable, Identifiable, Hashable {
     var transcriptChunks: [TranscriptChunk]
     var userNotes: String
     var generatedNotes: String
+    // MARK: - Data versioning
+    /// Version of this Meeting record on disk. Useful for migration.
+    var dataVersion: Int
+    /// Current app data version. Increment whenever you make a breaking change to `Meeting` that requires migration.
+    static let currentDataVersion = 1
     
     init(id: UUID = UUID(), 
          date: Date = Date(),
          title: String = "",
          transcriptChunks: [TranscriptChunk] = [],
          userNotes: String = "", 
-         generatedNotes: String = "") {
+         generatedNotes: String = "",
+         dataVersion: Int = Meeting.currentDataVersion) {
         self.id = id
         self.date = date
         self.title = title
         self.transcriptChunks = transcriptChunks
         self.userNotes = userNotes
         self.generatedNotes = generatedNotes
+        self.dataVersion = dataVersion
     }
     
+    // `Codable` conformance now uses the compiler-synthesised implementation.
+    
     // Computed property for backward compatibility with existing code
     var transcript: String {
         return transcriptChunks