Fix CloudKit data loss on delete-then-reinsert

Fixes #418

Author: jsutula

Sources/SQLiteData/CloudKit/Internal/MockSyncEngine.swift

@@ -173,8 +173,15 @@
     }
 
     package func add(pendingRecordZoneChanges: [CKSyncEngine.PendingRecordZoneChange]) {
-      self._pendingRecordZoneChanges.withValue {
-        $0.append(contentsOf: pendingRecordZoneChanges)
+      self._pendingRecordZoneChanges.withValue { set in
+        for change in pendingRecordZoneChanges {
+          if let id = change.id,
+             let supersededIndex = set.firstIndex(where: { $0.id == id && $0 != change })
+          {
+            set.remove(at: supersededIndex)
+          }
+          set.append(change)
+        }
       }
     }
 
@@ -185,8 +192,15 @@
     }
 
     package func add(pendingDatabaseChanges: [CKSyncEngine.PendingDatabaseChange]) {
-      self._pendingDatabaseChanges.withValue {
-        $0.append(contentsOf: pendingDatabaseChanges)
+      self._pendingDatabaseChanges.withValue { set in
+        for change in pendingDatabaseChanges {
+          if let zoneID = change.zoneID,
+            let supersededIndex = set.firstIndex(where: { $0.zoneID == zoneID && $0 != change })
+          {
+            set.remove(at: supersededIndex)
+          }
+          set.append(change)
+        }
       }
     }
 

Sources/SQLiteData/CloudKit/Internal/Triggers.swift

@@ -82,6 +82,16 @@
             defaultZone: defaultZone,
             privateTables: privateTables
           )
+          SyncMetadata
+            .where {
+              $0.recordPrimaryKey.eq(#sql("\(new.primaryKey)"))
+                && $0.recordType.eq(tableName)
+                && $0._isDeleted
+            }
+            .update {
+              $0._isDeleted = false
+              $0.userModificationTime = $currentTime()
+            }
         }
       )
     }
@@ -242,6 +252,7 @@
         afterZoneUpdateTrigger(),
         afterUpdateTrigger(for: syncEngine),
         afterSoftDeleteTrigger(for: syncEngine),
+        afterUndeleteTrigger(for: syncEngine),
       ]
     }
 
@@ -348,6 +359,29 @@
         }
       )
     }
+
+    fileprivate static func afterUndeleteTrigger(
+      for syncEngine: SyncEngine
+    ) -> TemporaryTrigger<Self> {
+      createTemporaryTrigger(
+        "\(String.sqliteDataCloudKitSchemaName)_after_undelete_on_sqlitedata_icloud_metadata",
+        ifNotExists: true,
+        after: .update(of: \._isDeleted) { _, new in
+          Values(
+            syncEngine.$didUpdate(
+              recordName: new.recordName,
+              zoneName: new.zoneName,
+              ownerName: new.ownerName,
+              oldZoneName: new.zoneName,
+              oldOwnerName: new.ownerName,
+              descendantRecordNames: #bind(nil)
+            )
+          )
+        } when: { old, new in
+          old._isDeleted && !new._isDeleted && !SyncEngine.$isSynchronizing
+        }
+      )
+    }
   }
 
   @available(iOS 17, macOS 14, tvOS 17, watchOS 10, *)

Sources/SQLiteData/CloudKit/SyncEngine.swift

@@ -2092,6 +2092,20 @@
     }
   }
 
+  @available(macOS 14, iOS 17, tvOS 17, watchOS 10, *)
+  extension CKSyncEngine.PendingDatabaseChange {
+    var zoneID: CKRecordZone.ID? {
+      switch self {
+      case .saveZone(let zone):
+        return zone.zoneID
+      case .deleteZone(let zoneID):
+        return zoneID
+      @unknown default:
+        return nil
+      }
+    }
+  }
+
   extension CKRecord.ID {
     var tableName: String? {
       guard