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 twostraws/SwiftData-Agent-Skill --skill swiftdata-progit clone --depth 1 https://github.com/twostraws/SwiftData-Agent-SkillWrote 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/twostraws/swiftdata-agent-skill/swiftdata-pro)<a href="https://agentmods.dev/skills/twostraws/swiftdata-agent-skill/swiftdata-pro"><img src="https://agentmods.dev/badge/skills/twostraws/swiftdata-agent-skill/swiftdata-pro/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/twostraws/swiftdata-agent-skill/swiftdata-pro"><img src="https://agentmods.dev/badge/skills/twostraws/swiftdata-agent-skill/swiftdata-pro.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- Snyk 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 | $0.00034 | $0.00819 |
| Opus 5.5 | $0.00014 | $0.00328 |
| Sonnet 5.5 | $0.00007 | $0.00164 |
| Haiku 4.5 | $0.00003 | $0.00082 |
Grade A, and why
swiftdata-pro scanned grade A with 1 finding 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 1mo 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
try modelContext.fetch(FetchDescriptor<Destination>()) Copies of this mod
1 near-identical copy found in the catalogue:
- swiftdata-pro — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 103 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Write and review SwiftData code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems - do not nitpick or invent issues.
Review process:
- Check for core SwiftData issues using
references/core-rules.md. - Check that predicates are safe and supported using
references/predicates.md. - If the project uses CloudKit, check for CloudKit-specific constraints using
references/cloudkit.md. - If the project targets iOS 18+, check for indexing opportunities using
references/indexing.md. - If the project targets iOS 26+, check for class inheritance patterns using
references/class-inheritance.md.
If doing partial work, load only the relevant reference files.
Core Instructions
- Target Swift 6.2 or later, using modern Swift concurrency.
- The user strongly prefers to use SwiftData across the board. Do not suggest Core Data functionality unless it is a feature that cannot be solved with SwiftData.
- Do not introduce third-party frameworks without asking first.
- Use a consistent project structure, with folder layout determined by app features.
Output Format
If the user asks for a review, organize findings by file. For each issue:
- State the file and relevant line(s).
- Name the rule being violated.
- Show a brief before/after code fix.
Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.
If the user asks you to write or improve code, follow the same rules above but make the changes directly instead of returning a findings report.
Example output:
Destination.swift
Line 8: Add an explicit delete rule for relationships.
// Before
var sights: [Sight]
// After
@Relationship(deleteRule: .cascade, inverse: \Sight.destination) var sights: [Sight]
Line 22: Do not use isEmpty == false in predicates – it crashes at runtime. Use ! instead.
// Before
#Predicate<Destination> { $0.sights.isEmpty == false }
// After
#Predicate<Destination> { !$0.sights.isEmpty }
What ships with it
8 files 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.
- 1mo ago First seen · 103 lines · 34 tokens per session scan A 79164f3bc494
swiftdata-pro is a skill published in the GitHub repository twostraws/SwiftData-Agent-Skill (452 stars, last pushed 3d ago), licensed MIT. It adds 34 tokens to every session and 819 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other skills, from other repositories
swift-actor-persistence
Thread-safe data persistence in Swift using actors — in-memory cache with file-backed storage, eliminating data races by design.
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.
axiom-audit-core-data
Use when the user mentions Core Data review, schema migration, production crashes, or data safety checking.
axiom-audit-swiftdata
Use when the user mentions SwiftData review, @Model issues, SwiftData migration safety, or SwiftData performance checking.
axiom-data
Use when working with ANY data persistence, database, storage, CloudKit, migration, or serialization in an Apple app. Covers SwiftData, Core Data, GRDB, SQLite, Realm, CloudKit sync, file storage, Codable, migrations.
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.