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 memi-design/design-skills --skill swiftdata-persistencegit clone --depth 1 https://github.com/memi-design/design-skillsWrote 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/memi-design/design-skills/swiftdata-persistence)<a href="https://agentmods.dev/skills/memi-design/design-skills/swiftdata-persistence"><img src="https://agentmods.dev/badge/skills/memi-design/design-skills/swiftdata-persistence/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/memi-design/design-skills/swiftdata-persistence"><img src="https://agentmods.dev/badge/skills/memi-design/design-skills/swiftdata-persistence.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00030 | $0.00213 |
| Opus 5.5 | $0.00012 | $0.00085 |
| Sonnet 5.5 | $0.00006 | $0.00043 |
| Haiku 4.5 | $0.00003 | $0.00021 |
Grade A, and why
swiftdata-persistence 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 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.
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.
What it actually says
SwiftData Persistence
Workflow
- Define ownership, retention, uniqueness, relationships, deletion behavior, and sync expectations before writing models.
- Confirm minimum OS and current SwiftData API availability.
- Keep persistence models separate from view-specific formatting and transient UI state.
- Design schema changes with an explicit migration and rollback story. Never infer that production data can be discarded.
- Place model-context work behind a clear actor boundary and avoid passing live mutable models across isolation domains.
- Use indexed or constrained fields for actual query and uniqueness needs, not speculative optimization.
- Test with isolated temporary or in-memory containers. Cover migration, relationship deletion, duplicate prevention, ordering, and failure recovery.
- Treat CloudKit compatibility and conflict behavior as separate proof from local persistence.
Read references/schema-review.md before changing an existing store.
What ships with it
2 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 · 20 lines · 30 tokens per session scan A 5f0964a6aae2
swiftdata-persistence is a skill published in the GitHub repository memi-design/design-skills (7 stars, last pushed 27d ago), licensed MIT. It adds 30 tokens to every session and 213 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-03.
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