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-swiftdatagit 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-swiftdata)<a href="https://agentmods.dev/skills/charleswiltgen/axiom/axiom-audit-swiftdata"><img src="https://agentmods.dev/badge/skills/charleswiltgen/axiom/axiom-audit-swiftdata/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-swiftdata"><img src="https://agentmods.dev/badge/skills/charleswiltgen/axiom/axiom-audit-swiftdata.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 | $0.00032 | $0.03562 |
| Opus 5 | $0.00016 | $0.01781 |
| Sonnet 5 | $0.00006 | $0.00712 |
| Haiku 4.5 | $0.00003 | $0.00356 |
Grade A, and why
axiom-audit-swiftdata 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.
How it starts
The opening of the file, as written. The whole thing — 284 lines — stays where its author put it; the contents beside it link to each section on GitHub.
SwiftData Auditor Agent
You are an expert at detecting SwiftData violations — both known anti-patterns AND missing/incomplete patterns that cause crashes, data loss, silent corruption, sync failures, 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 SwiftData Architecture
Step 1: Identify the @Model Inventory
Glob: **/*.swift (excluding test/vendor paths)
Grep for:
- `@Model\s+(final\s+)?class\s+\w+` — every @Model class declaration
- `@Model\s+struct` — illegal struct models (Pattern 1)
- `@Attribute(` — attribute customization
- `@Relationship(` — relationship declarations and inverses
- `@Transient` — properties excluded from persistence
Step 2: Identify Container & Context Topology
Grep for:
- `ModelContainer(` — container construction sites
- `ModelConfiguration(` — configuration (App Group, CloudKit, in-memory)
- `.modelContainer(` — view modifier hookup
- `@Environment(\.modelContext)` — UI-side context use
- `ModelContext(` — explicit (often background) context creation
- `mainContext` — explicit main-context access
- `isAutosaveEnabled` — autosave configuration
Step 3: Identify Migration Surface
Grep for:
- `VersionedSchema` — schema versions
- `static var versionIdentifier` — version markers
- `static var models` — model arrays per version
- `SchemaMigrationPlan` — migration plan
- `MigrationStage.lightweight`, `MigrationStage.custom` — stage types
- `willMigrate`, `didMigrate` — custom migration hooks
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.
- 6d ago First seen · 284 lines · 32 tokens per session scan A f37b73022440
axiom-audit-swiftdata is a skill published in the GitHub repository CharlesWiltgen/Axiom (1,155 stars, last pushed 3d ago), licensed MIT. It adds 32 tokens to every session and 3,562 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 2026-09-06.
Other skills, from other repositories
setup-datamodel
Use when the user wants to design or redesign the Dataverse schema and connector plan for an existing mobile app, or has an ER diagram (image, Mermaid, or text) to apply. Skip when the user is creating a brand-new app — /create-mobile-app handles the data model inline.
firebase-database
Use when syncing real-time data, structuring JSON trees, reading/writing, creating listeners, enabling offline persistence, managing presence, sharding, or writing security rules.
android-persistence
Implement Room schemas and DataStore preferences with proper async patterns in Android. Use when the primary task is storage schema, DAO, migration, or preference isolation; defer auth-token/security storage, any CoroutineWorker/WorkManager task, Hilt graph wiring, and cache-policy design.
android-data-layer
Guidance on implementing the Data Layer using Repository pattern, Room (Local), and Retrofit (Remote) with offline-first synchronization.
boutique-store
Create and use Boutique Store for Swift data persistence, including initialization, @Stored controllers, CRUD operations, operation chaining, and granular event monitoring. Use when persisting arrays of items, building data controllers, or working with Boutique's Store type.
boutique-stored-values
Persist individual values with Boutique's @StoredValue (UserDefaults) and @SecurelyStoredValue (Keychain), including set, reset, toggle, bindings, keypath setters, array and dictionary helpers, and async observation. Use when storing preferences, settings, feature flags, or sensitive data like auth tokens.