cloudkit-sync

cloudkit-sync is a skill for Claude Code from rshankras/claude-code-apple-skills. It costs 37 tokens per session (2,686 once invoked), scanned A, original, MIT.

A generator for adding iCloud data synchronization to iOS and macOS apps with Apple's CloudKit service. It creates infrastructure for syncing records, resolving conflicts, sharing data, and monitoring account status.

In plain words
What is it for?
Use it when adding CloudKit sync, cross-device data sharing, conflict handling, or iCloud account monitoring to an app.
Why use it?
It reduces the manual work needed to keep app data consistent across devices and handle competing changes or shared records.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: names the AskUserQuestion tool.

Part of the apple-skills plugin — 147 skills shipped together , and of apple-skills

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/rshankras/claude-code-apple-skills/cloudkit-sync
Any agent
npx skills add rshankras/claude-code-apple-skills --skill cloudkit-sync
Clone the repo
git clone --depth 1 https://github.com/rshankras/claude-code-apple-skills

Made for: Claude Code.

Or install apple-skills, the plugin that ships this one along with the rest of its 147 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for cloudkit-sync

README.md
[![agentmods](https://agentmods.dev/badge/skills/rshankras/claude-code-apple-skills/cloudkit-sync.svg)](https://agentmods.dev/skills/rshankras/claude-code-apple-skills/cloudkit-sync)
Your own site
<a href="https://agentmods.dev/skills/rshankras/claude-code-apple-skills/cloudkit-sync"><img src="https://agentmods.dev/badge/skills/rshankras/claude-code-apple-skills/cloudkit-sync.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,686 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.02686
Opus 5 $0.00018 $0.01343
Sonnet 5 $0.00007 $0.00537
Haiku 4.5 $0.00004 $0.00269

Measured 6d ago against content hash 51a56b047105, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

cloudkit-sync scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/generators/cloudkit-sync/SKILL.md · 357 lines

How it starts

The opening of the file, as written. The whole thing — 357 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CloudKit Sync Generator

Generate production-ready CloudKit sync infrastructure using CKSyncEngine (iOS 17+ / macOS 14+), the modern replacement for manual CKOperation chains.

When This Skill Activates

Use this skill when the user:

  • Asks to "add iCloud sync" or "sync data across devices"
  • Mentions "CloudKit", "CKSyncEngine", or "cloud sync"
  • Wants to "share data between users" via iCloud
  • Asks about "conflict resolution" for synced data
  • Mentions "CKRecord", "CKShare", or "CKRecordZone"

Pre-Generation Checks

1. Project Context Detection

Before generating, ALWAYS check:

# Check deployment target (CKSyncEngine requires iOS 17+ / macOS 14+)
grep -r "platform" Package.swift 2>/dev/null || true
grep -r "IPHONEOS_DEPLOYMENT_TARGET\|MACOSX_DEPLOYMENT_TARGET" --include="*.pbxproj" | head -3

# Find existing CloudKit implementations
rg -l "CKSyncEngine\|CKContainer\|CKRecord\|CKOperation" --type swift | head -10

# Check for existing entitlements
find . -name "*.entitlements" -exec cat {} \; 2>/dev/null | grep -i "icloud"

# Check existing persistence layer
rg -l "@Model\|NSManagedObject\|PersistentModel" --type swift | head -5

# Check for existing sync infrastructure
rg "CKSyncEngineDelegate\|CKSubscription\|CKFetchRecordZoneChanges" --type swift | head -5

2. Compatibility Verification

CKSyncEngine requires:

  • iOS 17.0+ / macOS 14.0+ / watchOS 10.0+ / tvOS 17.0+
  • CloudKit entitlement
  • Active iCloud account on device

If deployment target is below iOS 17 / macOS 14, warn the user that CKSyncEngine is not available and suggest either raising the target or using the older CKOperation approach (which this generator does not cover).

3. Conflict Detection

If existing CloudKit code is found:

  • Ask: Replace existing implementation, extend it, or migrate to CKSyncEngine?

Configuration Questions

Ask user via AskUserQuestion:

  1. What data needs syncing?
    • Provide your model types (e.g., Note, Task, Document)
    • What properties does each model have?

Read the full file on GitHub · 357 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 357 lines · 37 tokens per session scan A 51a56b047105

Subscribe to this mod's changes

cloudkit-sync is a skill published in the GitHub repository rshankras/claude-code-apple-skills (700 stars, last pushed 1mo ago), licensed MIT. It adds 37 tokens to every session and 2,686 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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