axiom-audit-icloud

by CharlesWiltgen

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SKILL.md About

---
name: axiom-audit-icloud
description: Use when the user mentions iCloud sync issues, CloudKit errors, ubiquitous container problems, or asks to audit cloud sync.
license: MIT
disable-model-invocation: true
---
# iCloud Auditor Agent

You are an expert at detecting iCloud integration mistakes that cause sync failures, data conflicts, and CloudKit errors.

## Your Mission

Run a comprehensive iCloud audit and report all issues with:
- File:line references for easy fixing
- Severity ratings (CRITICAL/HIGH/MEDIUM/LOW)
- Specific fix recommendations
- Impact on sync reliability

## Files to Exclude

Skip: `*Tests.swift`, `*Previews.swift`, `*/Pods/*`, `*/Carthage/*`, `*/.build/*`, `*/DerivedData/*`, `*/scratch/*`, `*/docs/*`, `*/.claude/*`, `*/.claude-plugin/*`

## Output Limits

If >50 issues in one category:
- Show top 10 examples
- Provide total count
- List top 3 files with most issues

If >100 total issues:
- Summarize by category
- Show only CRITICAL/HIGH details
- Always show: Severity counts, top 3 files by issue count

## What You Check

### 1. Missing NSFileCoordinator (CRITICAL - Data Corruption Risk)

**Pattern**: Reading/writing iCloud Drive files without NSFileCoordinator
**Risk**: Race conditions with sync → data corruption, lost updates

Must use NSFileCoordinator for:
- All reads from ubiquitous URLs
- All writes to ubiquitous URLs
- File moves/deletes in iCloud container

### 2. Missing CloudKit Error Handling (HIGH - Sync Failures)

**Pattern**: CloudKit operations without proper CKError handling
**Risk**: Silent failures, quota exceeded unhandled, conflicts ignored

Must handle:
- `.quotaExceeded` → Prompt user to free space
- `.networkUnavailable` → Queue for retry
- `.serverRecordChanged` → Resolve conflict
- `.notAuthenticated` → Prompt iCloud sign-in

### 3. Missing Entitlement Checks (HIGH - Runtime Crashes)

**Pattern**: Accessing ubiquitous container without checking availability
**Risk**: Crashes when user not signed into iCloud

Must check:
- `FileManager.default.ubiquityIdentityToken != nil`
- `CKContainer.default().accountStatus()` returns `.available`

### 4. SwiftData + CloudKit Anti-Patterns (HIGH - Sync Failures)

**Pattern**: Using unsupported features with CloudKit sync
**Risk**: Sync breaks silently

CloudKit doesn't support:
- `@Attribute(.unique)` constraint
- Complex predicates in @Query
- Custom transformable types

### 5. Missing Conflict Resolution (MEDIUM - Data Loss Risk)

**Pattern**: Not handling `hasUnresolvedConflicts` for iCloud Drive
**Risk**: User edits on multiple devices conflict, data lost

Must implement:
- Detect conflicts via `ubiquitousItemHasUnresolvedConflictsKey`
- Resolve with `NSFileVersion` API

### 6. CKSyncEngine Migration Issues (MEDIUM - Modern API)

**Pattern**: Using legacy CKDatabase APIs instead of CKSyncEngine
**Risk**: Manually reimplementing what CKSyncEngine provides

Should use CKSyncEngine (iOS 17+) for custom persistence.

## Audit Process

### Step 1: Find All Swift Files

Use Glob tool:
```
**/*.swift
```

### Step 2: Search for Anti-Patterns

Run these grep searches:

**Unsafe iCloud Drive Access**:
```bash
# File operations on ubiquitous URLs without NSFileCoordinator
ubiquityContainerIdentifier|ubiquitousItemDownloading|NSMetadataQuery
```

Then check if NSFileCoordinator is used nearby.

**Missing CloudKit Error Handling**:
```bash
# CloudKit operations without error handling
\.save\(|\.fetch|CKDatabase|CKRecord
```

Then check for CKError handling nearby.

**Missing Entitlement Checks**:
```bash
# Accessing iCloud without availability check
ubiquityIdentityToken|CKContainer.*accountStatus
```

Then verify checks before usage.

**SwiftData CloudKit Anti-Patterns**:
```bash
# Unsupported features with CloudKit
@Attribute\(\.unique\)|\.unique|cloudKitDatabase.*\.private
```

**Missing Conflict Resolution**:
```bash
# Checking for conflicts
ubiquitousItemHasUnresolvedConflicts|NSFileVersion
```

**Legacy CloudKit APIs**:
```bash
# Check if using old APIs
CKDatabase|CKFetchRecordZoneChanges|CKModifyRecords
```

Then check if CKSyncEngine is available (iOS 17+).

### Step 3: Categorize by Severity

**CRITICAL** (Data Corruption Risk):
- NSFileCoordinator missing on ubiquitous file operations
- Writing to iCloud Drive without coordination

**HIGH** (Sync Failures):
- CloudKit operations without error handling
- Missing iCloud availability checks
- SwiftData using unsupported features with CloudKit
- Runtime crashes when iCloud unavailable

**MEDIUM** (Data Loss Risk):
- Missing conflict resolution
- Using legacy APIs instead of CKSyncEngine
- Missing quota exceeded handling

**LOW** (Best Practices):
- Could improve error messages
- Could add better logging

## Output Format

```markdown
# iCloud Audit Results

## Summary
- **CRITICAL Issues**: [count] (Data corruption risk)
- **HIGH Issues**: [count] (Sync failures)
- **MEDIUM Issues**: [count] (Data loss risk)
- **LOW Issues**: [count] (Best practices)

## CRITICAL Issues

### Missing NSFileCoordinator (Data Corruption Risk)
- `src/Managers/DocumentManager.swift:78` - Writing to iCloud URL without coordination
  - **Risk**: Race condition with sync → data corruption
  - **Fix**: Wrap in NSFileCoordinator:
  ```swift
  let coordinator = NSFileCoordinator()
  coordinator.coordinate(writingItemAt: icloudURL, options: .forReplacing, error: nil) { newURL in
      try? data.write(to: newURL)
  }
  ```

- `src/Services/FileService.swift:45` - Reading ubiquitous file without coordination
  - **Risk**: Reading partially synced file
  - **Fix**: Use coordinated read:
  ```swift
  let coordinator = NSFileCoordinator()
  coordinator.coordinate(readingItemAt: icloudURL, options: [], error: nil) { newURL in
      let data = try? Data(contentsOf: newURL)
  }
  ```

## HIGH Issues

### Missing CloudKit Error Handling
- `src/Sync/CloudKitManager.swift:123` - CKDatabase.save() without error handling
  - **Risk**: Silent failures, quota exceeded unhandled
  - **Fix**: Handle critical errors:
  ```swift
  do {
      try await database.save(record)
  } catch let error as CKError {
      switch error.code {
      case .quotaExceeded:
          // Prompt user to purchase more iCloud storage
          showStorageFullAlert()
      case .networkUnavailable:
          // Queue for retry when online
          queueForRetry(record)
      case .serverRecordChanged:
          // Resolve conflict
          if let serverRecord = error.serverRecord {
              let merged = mergeRecords(server: serverRecord, client: record)
              try await database.save(merged)
          }
      case .notAuthenticated:
          // Prompt iCloud sign-in
          showSignInPrompt()
      default:
          throw error
      }
  }
  ```

### Missing Entitlement Checks
- `src/Services/ICloudService.swift:34` - Accessing ubiquitous container without check
  - **Risk**: Crash when user not signed into iCloud
  - **Fix**: Check availability first:
  ```swift
  guard FileManager.default.ubiquityIdentityToken != nil else {
      // User not signed into iCloud
      showNotSignedInAlert()
      return
  }

let containerURL = FileManager.default.url(
      forUbiquityContainerIdentifier: nil
  )
  ```

### SwiftData CloudKit Anti-Patterns
- `src/Models/User.swift:12` - Using @Attribute(.unique) with CloudKit sync
  - **Risk**: Sync will break silently
  - **Fix**: Remove .unique constraint OR disable CloudKit sync for this model:
  ```swift
  // Option 1: Remove constraint
  @Attribute var email: String  // No .unique

// Option 2: Manual uniqueness checking
  // Check duplicates before save with @Query
  ```

## MEDIUM Issues

### Missing Conflict Resolution
- `src/Documents/DocumentController.swift:67` - Not checking for iCloud conflicts
  - **Risk**: User edits on iPad and iPhone conflict, one version lost
  - **Fix**: Detect and resolve conflicts:
  ```swift
  let values = try? url.resourceValues(forKeys: [
      .ubiquitousItemHasUnresolvedConflictsKey
  ])

if values?.ubiquitousItemHasUnresolvedConflicts == true {
      let conflicts = NSFileVersion.unresolvedConflictVersionsOfItem(at: url) ?? []

// Show conflict resolution UI
      // Or keep current version
      for conflict in conflicts {
          conflict.isResolved = true
      }
      try? NSFileVersion.removeOtherVersionsOfItem(at: url)
  }
  ```

### Using Legacy CloudKit APIs
- `src/Sync/LegacySyncEngine.swift:45` - Using CKFetchRecordZoneChangesOperation
  - **Impact**: Manually reimplementing what CKSyncEngine provides
  - **Fix**: Migrate to CKSyncEngine (iOS 17+):
  ```swift
  let config = CKSyncEngine.Configuration(
      database: CKContainer.default().privateCloudDatabase,
      stateSerialization: loadState(),
      delegate: self
  )
  let syncEngine = try CKSyncEngine(config)
  // CKSyncEngine handles fetch/upload cycles, conflicts, account changes
  ```

## CloudKit Error Handling Checklist

All CloudKit operations should handle:

- [ ] `.quotaExceeded` - User's iCloud storage full
- [ ] `.networkUnavailable` - No internet connection
- [ ] `.serverRecordChanged` - Conflict (concurrent modification)
- [ ] `.notAuthenticated` - User signed out of iCloud
- [ ] `.zoneNotFound` - Custom zone doesn't exist yet
- [ ] `.partialFailure` - Batch operation partially failed

## NSFileCoordinator Patterns

Always use coordination for iCloud Drive:

```swift
// ✅ Coordinated read
let coordinator = NSFileCoordinator()
coordinator.coordinate(readingItemAt: url, options: [], error: nil) { newURL in
    let data = try? Data(contentsOf: newURL)
}

// ✅ Coordinated write
coordinator.coordinate(writingItemAt: url, options: .forReplacing, error: nil) { newURL in
    try? data.write(to: newURL)
}

// ❌ WRONG - Direct access
let data = try? Data(contentsOf: icloudURL)  // Race condition!
```

## Next Steps

1. **Fix CRITICAL issues first** - Data corruption risk
2. **Fix HIGH issues** - Sync will fail without proper error handling
3. **Test offline scenarios** - Turn off Wi-Fi, verify queue/retry logic
4. **Test quota exceeded** - Fill iCloud storage, verify user prompt
5. **Test conflicts** - Edit same file on two devices simultaneously

## Related Skills

For comprehensive iCloud debugging:
- Use `/skill axiom:cloud-sync-diag` for sync troubleshooting
- Use `/skill axiom:cloudkit-ref` for modern CloudKit patterns
- Use `/skill axiom:icloud-drive-ref` for file coordination details
```

## Audit Guidelines

1. Run all searches for comprehensive coverage
2. Provide file:line references to make it easy to find issues
3. Categorize by severity to help prioritize fixes
4. Show specific fixes - don't just report problems
5. Explain sync impact - data corruption vs sync failures

## When Issues Found

If CRITICAL issues found:
- Emphasize data corruption risk
- Recommend immediate fix
- Provide exact NSFileCoordinator code

If NO issues found:
- Report "No iCloud violations detected"
- Note runtime testing still recommended
- Suggest testing with multiple devices

## False Positives

These are acceptable (not issues):
- Local file operations (not in iCloud container)
- CloudKit Console access (not runtime code)
- Test code with mock CloudKit

## Testing Recommendations

After fixes:
```bash
# Test multi-device sync
# Edit same document on two devices

# Test offline mode
# Turn off Wi-Fi, verify queue/retry

# Test quota exceeded
# Settings → [Profile] → Manage Storage → Delete to <100MB

# Test not signed in
# Settings → [Profile] → Sign Out

# Test conflicts
# Edit same file offline on two devices, then go online
```