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 ComeOnOliver/skillshub --skill axiom-keychaingit clone --depth 1 https://github.com/ComeOnOliver/skillshubWrote 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/comeonoliver/skillshub/axiom-keychain)<a href="https://agentmods.dev/skills/comeonoliver/skillshub/axiom-keychain"><img src="https://agentmods.dev/badge/skills/comeonoliver/skillshub/axiom-keychain/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/comeonoliver/skillshub/axiom-keychain"><img src="https://agentmods.dev/badge/skills/comeonoliver/skillshub/axiom-keychain.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 | $0.00076 | $0.06206 |
| Opus 5 | $0.00038 | $0.03103 |
| Sonnet 5 | $0.00015 | $0.01241 |
| Haiku 4.5 | $0.00008 | $0.00621 |
Grade A, and why
axiom-keychain 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 9d 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 — 546 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Keychain Services
Secure credential storage, SecItem API mental model, uniqueness constraints, data protection classes, biometric access control, keychain sharing, and Mac keychain differences for iOS/macOS apps.
When to Use This Skill
Use when you need to:
- ☑ Store tokens, passwords, API keys, or cryptographic keys securely
- ☑ Debug errSecDuplicateItem, errSecItemNotFound, or errSecInteractionNotAllowed
- ☑ Choose the right kSecAttrAccessible level for your use case
- ☑ Add biometric or passcode protection to a keychain item
- ☑ Share credentials between apps or app extensions via access groups
- ☑ Migrate from UserDefaults/@AppStorage to keychain for sensitive data
- ☑ Understand why SecItemCopyMatching returns something different than expected
- ☑ Store or retrieve keychain items from a background context
Example Prompts
"How do I store an auth token in the keychain?" "errSecDuplicateItem when saving to keychain but the item doesn't exist" "My keychain read fails in background refresh" "How do I add Face ID protection to a keychain item?" "Share keychain items between my app and widget extension" "What's the difference between kSecAttrAccessibleAfterFirstUnlock and WhenUnlocked?" "SecItemCopyMatching returns errSecItemNotFound but I just saved it" "How do I use the keychain on macOS with Catalyst?" "My keychain wrapper is returning nil — how do I debug this?" "errSecInteractionNotAllowed in background task"
Red Flags
Signs you're making this harder than it needs to be:
- ❌ Using a keychain wrapper without understanding SecItem — Wrappers hide the 4-function model and introduce their own bugs. Quinn "The Eskimo!" explicitly warns: most wrapper issues stem from the wrapper, not the keychain. Learn the model first.
- ❌ Storing tokens in UserDefaults or @AppStorage — These are plist files readable by anyone with device access (or a backup). Credentials belong in the keychain. No exceptions.
- ❌ Force-unwrapping SecItemCopyMatching results — The return type depends on which kSecReturn* flags you passed. A mismatch gives you a surprising type, not your data.
- ❌ Not specifying kSecAttrAccessible — Defaults to kSecAttrAccessibleWhenUnlocked, which fails in background execution. If your app does background refresh, push processing, or VoIP, this will bite you.
- ❌ Catching errSecDuplicateItem by deleting then re-adding — This creates a race condition and destroys metadata (creation date, access control). Use SecItemUpdate instead.
- ❌ Using kSecMatchLimitAll without understanding delete semantics — SecItemDelete has no kSecMatchLimit; it deletes ALL matching items. One careless query can wipe credentials.
- ❌ Ignoring errSecDuplicateItem — "It worked last time" means you have a query/uniqueness mismatch. This is the #1 keychain bug.
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.
- 9d ago First seen · 546 lines · 76 tokens per session scan A 6e74ea18e0e9
axiom-keychain is a skill published in the GitHub repository ComeOnOliver/skillshub (63 stars, last pushed 2mo ago), licensed MIT. It adds 76 tokens to every session and 6,206 once invoked, about $0.0004 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 2026-09-03.
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