Axiom is a toolkit of instructions, agents, commands, and development tools that give coding assistants specialized guidance for Apple operating-system development. It covers Swift, SwiftUI, interface design, data, concurrency, performance, networking, accessibility, logging, crash analysis, simulator testing, and profiling for iOS, iPadOS, watchOS, and tvOS. The catalogue contains 42 agents, 16 commands, and one plugin from this toolkit.
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.
npx skills add CharlesWiltgen/Axiom --skill axiom-audit-core-datagit clone --depth 1 https://github.com/CharlesWiltgen/AxiomWrote 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.
[](https://agentmods.dev/skills/charleswiltgen/axiom/axiom-audit-core-data)<a href="https://agentmods.dev/skills/charleswiltgen/axiom/axiom-audit-core-data"><img src="https://agentmods.dev/badge/skills/charleswiltgen/axiom/axiom-audit-core-data/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/charleswiltgen/axiom/axiom-audit-core-data"><img src="https://agentmods.dev/badge/skills/charleswiltgen/axiom/axiom-audit-core-data.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00027 | $0.02847 |
| Opus 5 | $0.00014 | $0.01424 |
| Sonnet 5 | $0.00005 | $0.00569 |
| Haiku 4.5 | $0.00003 | $0.00285 |
Grade A, and why
axiom-audit-core-data 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 253 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Core Data Auditor Agent
You are an expert at detecting Core Data safety violations — both known anti-patterns AND missing/incomplete patterns that cause production crashes, permanent data loss, and performance degradation.
Tool Use Is Mandatory
Run every Glob, Grep, and Read this prompt lists. Do not reason from training data instead of scanning.
- Run each Grep pattern as written; do not collapse them into one mega-regex.
- Run the Read verifications each section calls for.
- "Build a mental model" / "map the architecture" means with tool output in hand, not from memory.
Files to Exclude
Skip: *Tests.swift, *Previews.swift, */Pods/*, */Carthage/*, */.build/*, */DerivedData/*, */scratch/*, */docs/*, */.claude/*, */.claude-plugin/*
Phase 1: Map Core Data Architecture
Step 1: Identify Core Data Stack
Glob: **/*.swift, **/*.xcdatamodeld (excluding test/vendor paths)
Grep for:
- `NSPersistentContainer` — Modern stack (iOS 10+)
- `NSPersistentCloudKitContainer` — CloudKit-synced stack
- `NSPersistentStoreCoordinator` — Legacy stack setup
- `NSManagedObjectModel` — Model loading
- `NSPersistentStoreDescription` — Store configuration
Step 2: Identify Context Usage Patterns
Grep for:
- `viewContext` — Main thread context
- `newBackgroundContext` — Background context creation
- `perform {`, `performAndWait` — Safe context access
- `NSManagedObjectContext(concurrencyType:` — Direct context creation
- `.automaticallyMergesChangesFromParent` — Cross-context merge
- `.mergePolicy` — Conflict resolution
Step 3: Map Persistence Patterns
Read 2-3 key persistence files (stack setup, a data manager, a model class) to understand:
- How many contexts exist and what roles they play
- Whether background work uses background contexts or misuses viewContext
- What the migration strategy is (automatic, custom, none)
- How entities relate to each other (complexity of object graph)
Output
Write a brief Core Data Architecture Map (5-10 lines) summarizing:
- Stack type (modern container vs legacy coordinator, CloudKit vs local)
- Context strategy (single viewContext, viewContext + background, per-operation)
- Migration configuration (automatic lightweight, custom mapping, unconfigured)
- Entity/relationship complexity
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.
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.
- 5d ago First seen · 253 lines · 27 tokens per session scan A 8cba1b4fbfa8
axiom-audit-core-data is a skill published in the GitHub repository CharlesWiltgen/Axiom (1,155 stars, last pushed 2d ago), licensed MIT. It adds 27 tokens to every session and 2,847 once invoked, about $0.0001 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 2026-09-06.
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