From 9ea5bdd88b79d7c9db88021e568c8a66789a21fa Mon Sep 17 00:00:00 2001
From: James Sutula <james@sutula.us>
Date: Sat, 7 Mar 2026 19:55:28 -0800
Subject: [PATCH] Setup to repro CloudKit data loss on delete-then-reinsert

---
 .../CloudKitDemo/CountersListFeature.swift    | 47 +++++++++++++++++--
 Examples/CloudKitDemo/Schema.swift            | 20 +++++++-
 2 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/Examples/CloudKitDemo/CountersListFeature.swift b/Examples/CloudKitDemo/CountersListFeature.swift
index ae9e0de0..bac46b9a 100644
--- a/Examples/CloudKitDemo/CountersListFeature.swift
+++ b/Examples/CloudKitDemo/CountersListFeature.swift
@@ -2,12 +2,15 @@ import CloudKit
 import SQLiteData
 import SwiftUI
 
+let initialAssetSize = 10
+
 struct CountersListView: View {
   @FetchAll(
     Counter
-      .leftJoin(SyncMetadata.all) { $0.syncMetadataID.eq($1.id) }
+      .leftJoin(CounterAsset.all) { $0.id.eq($1.counterID) }
+      .leftJoin(SyncMetadata.all) { $0.syncMetadataID.eq($2.id) }
       .select {
-        Row.Columns(counter: $0, isShared: $1.isShared.ifnull(false))
+        Row.Columns(counter: $0, counterAsset: $1, isShared: $2.isShared.ifnull(false))
       }
   ) var rows
   @Dependency(\.defaultDatabase) var database
@@ -15,6 +18,7 @@ struct CountersListView: View {
 
   @Selection struct Row {
     let counter: Counter
+    let counterAsset: CounterAsset?
     let isShared: Bool
   }
 
@@ -39,10 +43,13 @@ struct CountersListView: View {
           Task {
             withErrorReporting {
               try database.write { db in
-                try Counter.insert {
+                let counterID = try Counter.insert {
                   Counter.Draft()
-                }
-                .execute(db)
+                }.returning(\.id)
+                  .fetchOne(db)!
+                try CounterAsset.insert {
+                  CounterAsset(counterID: counterID, assetData: Data(count: initialAssetSize))
+                }.execute(db)
               }
             }
           }
@@ -66,6 +73,7 @@ struct CountersListView: View {
 struct CounterRow: View {
   let row: CountersListView.Row
   @State var sharedRecord: SharedRecord?
+  @State var updateAssetCount = 0
   @Dependency(\.defaultDatabase) var database
   @Dependency(\.defaultSyncEngine) var syncEngine
 
@@ -83,6 +91,16 @@ struct CounterRow: View {
           incrementButtonTapped()
         }
         Spacer()
+        if let assetData = row.counterAsset?.assetData {
+          Text("Asset: \(assetData.count) bytes")
+        } else {
+          Text("<no asset>").foregroundStyle(.red)
+        }
+        Spacer()
+        Button("Update asset") {
+          updateAssetCount += 1
+          updateAssetButtonTapped()
+        }
         Button {
           shareButtonTapped()
         } label: {
@@ -124,6 +142,25 @@ struct CounterRow: View {
       }
     }
   }
+  
+  func updateAssetButtonTapped() {
+    withErrorReporting {
+      let sizeInBytes = initialAssetSize + updateAssetCount
+      let assetData = Data(count: sizeInBytes)
+      try database.write { db in
+        // This delete isn't strictly necessary, but it's
+        // what causes the data loss
+        try CounterAsset
+          .where { $0.counterID.eq(row.counter.id) }
+          .delete()
+          .execute(db)
+        
+        try CounterAsset.upsert {
+          CounterAsset(counterID: row.counter.id, assetData: assetData)
+        }.execute(db)
+      }
+    }
+  }
 }
 
 #Preview {
diff --git a/Examples/CloudKitDemo/Schema.swift b/Examples/CloudKitDemo/Schema.swift
index b4194cc1..19206655 100644
--- a/Examples/CloudKitDemo/Schema.swift
+++ b/Examples/CloudKitDemo/Schema.swift
@@ -8,6 +8,13 @@ nonisolated struct Counter: Identifiable {
   var count = 0
 }
 
+@Table
+nonisolated struct CounterAsset: Identifiable {
+  @Column(primaryKey: true) public let counterID: Counter.ID
+  public var id: Counter.ID { counterID }
+  public var assetData: Data
+}
+
 extension DependencyValues {
   mutating func bootstrapDatabase() throws {
     var configuration = Configuration()
@@ -37,11 +44,22 @@ extension DependencyValues {
       )
       .execute(db)
     }
+    migrator.registerMigration("Add CounterAsset") { db in
+      try #sql(
+        """
+        CREATE TABLE "counterAssets" (
+          "counterID" TEXT PRIMARY KEY NOT NULL,
+          "assetData" BLOB NOT NULL DEFAULT (x'')
+        ) STRICT
+        """
+      )
+      .execute(db)
+    }
     try migrator.migrate(database)
     defaultDatabase = database
     defaultSyncEngine = try SyncEngine(
       for: defaultDatabase,
-      tables: Counter.self
+      tables: Counter.self, CounterAsset.self
     )
   }
 }