1.6.0 #3: limpieza CloudKit-safe de duplicados de defaults (merge + Nullify)

Reglas de borrado Account.sources/goals y Category.sources: Cascade -> Nullify.
Así un borrado de padre (local o propagado por CloudKit al importar) NUNCA arrasa
hijos — elimina de raíz el mecanismo del desastre del build 68. Además es mejor UX
(borrar una categoría ya no borra todas sus sources+snapshots).

CoreDataStack.mergeDefaultDuplicates(): fusiona los Account 'Default' duplicados y
las categorías duplicadas por nombre en un ganador DETERMINISTA (el registro con el
UUID estable si existe, si no earliest createdAt / menor UUID → todos los dispositivos
convergen). Reasigna sources/goals al ganador y borra los perdedores (seguro por Nullify).
Llamado en la carga inicial y tras cada import remoto.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01L2p3gUZRNWW388rWFRjiU7

PortfolioJournal/Models/CoreData/PortfolioJournal.xcdatamodeld/PortfolioJournal.xcdatamodel/contents

@@ -21,8 +21,8 @@
         <attribute name="name" attributeType="String" defaultValueString=""/>
         <attribute name="notificationFrequency" attributeType="String" defaultValueString="monthly"/>
         <attribute name="sortOrder" attributeType="Integer 16" defaultValueString="0" usesScalarValueType="YES"/>
-        <relationship name="goals" optional="YES" toMany="YES" deletionRule="Cascade" destinationEntity="Goal" inverseName="account" inverseEntity="Goal"/>
+        <relationship name="goals" optional="YES" toMany="YES" deletionRule="Nullify" destinationEntity="Goal" inverseName="account" inverseEntity="Goal"/>
-        <relationship name="sources" optional="YES" toMany="YES" deletionRule="Cascade" destinationEntity="InvestmentSource" inverseName="account" inverseEntity="InvestmentSource"/>
+        <relationship name="sources" optional="YES" toMany="YES" deletionRule="Nullify" destinationEntity="InvestmentSource" inverseName="account" inverseEntity="InvestmentSource"/>
     </entity>
     <entity name="Category" representedClassName="Category" syncable="YES">
         <attribute name="allocationTarget" optional="YES" attributeType="Double" usesScalarValueType="NO"/>
@@ -32,7 +32,7 @@
         <attribute name="id" optional="YES" attributeType="UUID" usesScalarValueType="NO"/>
         <attribute name="name" attributeType="String" defaultValueString=""/>
         <attribute name="sortOrder" attributeType="Integer 16" defaultValueString="0" usesScalarValueType="YES"/>
-        <relationship name="sources" optional="YES" toMany="YES" deletionRule="Cascade" destinationEntity="InvestmentSource" inverseName="category" inverseEntity="InvestmentSource"/>
+        <relationship name="sources" optional="YES" toMany="YES" deletionRule="Nullify" destinationEntity="InvestmentSource" inverseName="category" inverseEntity="InvestmentSource"/>
     </entity>
     <entity name="InvestmentSource" representedClassName="InvestmentSource" syncable="YES">
         <attribute name="createdAt" optional="YES" attributeType="Date" usesScalarValueType="NO"/>

PortfolioJournal/Models/CoreDataStack.swift

@@ -213,12 +213,11 @@ class CoreDataStack: ObservableObject {
             }
             DispatchQueue.main.async {
                 self?.isLoaded = true
-                // NOTE: automatic logical dedup DISABLED. Deleting cascade-parent
+                // Merge the pre-stable-UUID default duplicates. Safe now: the merge
-                // entities (Account/Category) and letting those deletes propagate via
+                // reassigns children then deletes losers, and the relevant relationships
-                // CloudKit can trigger the Cascade delete rule on OTHER devices before
+                // use the Nullify delete rule so a propagated parent-delete can never
-                // the child-reassignment transaction imports — cascade-wiping sources
+                // cascade-wipe children (unlike the build-68 Cascade disaster).
-                // and snapshots. This caused total data loss across devices on build 68.
+                self?.mergeDefaultDuplicates()
-                // Dedup must be redesigned to be CloudKit-safe before re-enabling.
                 MonthlyCheckInStore.migrateIfNeeded()
                 // Migrate device-local UserDefaults data into Core Data so it syncs via iCloud.
                 MonthlyContributionStore.migrateIfNeeded(context: container.viewContext)
@@ -466,6 +465,86 @@ class CoreDataStack: ObservableObject {
         return removed
     }
 
+    // MARK: - Merge Default Duplicates (CloudKit-safe)
+
+    /// Merges the duplicate default Accounts and Categories that piled up before
+    /// the stable-UUID fix (per-device "Default" accounts + default categories with
+    /// random UUIDs). CloudKit-safe now because Account.sources/goals and
+    /// Category.sources use the Nullify delete rule — so a merged-away parent's
+    /// delete can never cascade-wipe children on any device (the build-68 disaster
+    /// was Cascade + cross-device import ordering). Children are reassigned to a
+    /// DETERMINISTIC winner (the stable-UUID record if present, else earliest
+    /// createdAt / lowest UUID) so every device converges on the same survivor.
+    @discardableResult
+    func mergeDefaultDuplicates() -> Int {
+        var merged = 0
+        let context = viewContext
+        context.performAndWait {
+            merged += mergeDefaultAccounts(in: context)
+            merged += mergeDuplicateCategories(in: context)
+            if context.hasChanges { try? context.save() }
+        }
+        return merged
+    }
+
+    private func deterministicWinner(_ objects: [NSManagedObject], stableID: UUID?) -> NSManagedObject? {
+        if let stableID, let canonical = objects.first(where: { ($0.value(forKey: "id") as? UUID) == stableID }) {
+            return canonical
+        }
+        return objects.sorted {
+            let a = ($0.value(forKey: "createdAt") as? Date) ?? .distantPast
+            let b = ($1.value(forKey: "createdAt") as? Date) ?? .distantPast
+            if a != b { return a < b }
+            let ida = ($0.value(forKey: "id") as? UUID)?.uuidString ?? ""
+            let idb = ($1.value(forKey: "id") as? UUID)?.uuidString ?? ""
+            return ida < idb
+        }.first
+    }
+
+    private func reassign(_ children: Any?, key: String, to winner: NSManagedObject) {
+        guard let set = children as? Set<NSManagedObject> else { return }
+        for child in Array(set) { child.setValue(winner, forKey: key) }
+    }
+
+    private func mergeDefaultAccounts(in context: NSManagedObjectContext) -> Int {
+        let request = NSFetchRequest<NSManagedObject>(entityName: "Account")
+        request.predicate = NSPredicate(format: "name == %@", Account.defaultAccountName)
+        guard let accounts = try? context.fetch(request), accounts.count > 1,
+              let winner = deterministicWinner(accounts, stableID: Account.defaultAccountStableID) else { return 0 }
+        var removed = 0
+        for loser in accounts where loser !== winner {
+            reassign(loser.value(forKey: "sources"), key: "account", to: winner)
+            reassign(loser.value(forKey: "goals"), key: "account", to: winner)
+            context.delete(loser)
+            removed += 1
+        }
+        if removed > 0 { print("[MergeDefaults] accounts: removed \(removed)") }
+        return removed
+    }
+
+    private func mergeDuplicateCategories(in context: NSManagedObjectContext) -> Int {
+        let request = NSFetchRequest<NSManagedObject>(entityName: "Category")
+        guard let categories = try? context.fetch(request), !categories.isEmpty else { return 0 }
+        var byName: [String: [NSManagedObject]] = [:]
+        for c in categories {
+            let name = (c.value(forKey: "name") as? String ?? "").trimmingCharacters(in: .whitespacesAndNewlines).lowercased()
+            guard !name.isEmpty else { continue }
+            byName[name, default: []].append(c)
+        }
+        var removed = 0
+        for (name, group) in byName where group.count > 1 {
+            let stable = Category.stableID(for: name)
+            guard let winner = deterministicWinner(group, stableID: stable) else { continue }
+            for loser in group where loser !== winner {
+                reassign(loser.value(forKey: "sources"), key: "category", to: winner)
+                context.delete(loser)
+                removed += 1
+            }
+        }
+        if removed > 0 { print("[MergeDefaults] categories: removed \(removed)") }
+        return removed
+    }
+
     // MARK: - Save Context
 
     func save() {
@@ -507,9 +586,12 @@ class CoreDataStack: ObservableObject {
             if removed > 0 {
                 print("[RemoteChanges] Removed \(removed) duplicate objects after CloudKit import")
             }
-            // NOTE: automatic logical dedup DISABLED here on purpose — see the load
+            // Merge default duplicates after each import (CloudKit-safe via Nullify
-            // block. Deleting cascade-parent entities and propagating those deletes
+            // rules + deterministic winner → devices converge, no cascade wipes).
-            // via CloudKit cascade-wiped children on other devices (build 68 incident).
+            let mergedDefaults = self.mergeDefaultDuplicates()
+            if mergedDefaults > 0 {
+                print("[RemoteChanges] Merged \(mergedDefaults) default duplicates after CloudKit import")
+            }
             // Notify repositories to re-fetch unconditionally.
             NotificationCenter.default.post(name: .cloudKitForceReload, object: nil)
             self.objectWillChange.send()