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-app-attestgit 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-app-attest)<a href="https://agentmods.dev/skills/comeonoliver/skillshub/axiom-app-attest"><img src="https://agentmods.dev/badge/skills/comeonoliver/skillshub/axiom-app-attest/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-app-attest"><img src="https://agentmods.dev/badge/skills/comeonoliver/skillshub/axiom-app-attest.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 | $0.00063 | $0.03593 |
| Opus 5 | $0.00032 | $0.01796 |
| Sonnet 5 | $0.00013 | $0.00719 |
| Haiku 4.5 | $0.00006 | $0.00359 |
Grade A, and why
axiom-app-attest 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 — 336 lines — stays where its author put it; the contents beside it link to each section on GitHub.
App Attest
Device-backed app integrity verification for fraud prevention. Proves three things to your server: the request came from a genuine Apple device, running your genuine app, with an untampered payload.
When to Use This Skill
Use when you need to:
- Verify requests come from legitimate app instances (not modified/cloned apps)
- Prevent fraud in purchases, promotions, or competitive features
- Implement DCAppAttestService attestation or assertion flows
- Handle DeviceCheck 2-bit per-device state for promotional abuse
- Build server-side validation for attestation objects or assertion signatures
- Plan a gradual App Attest rollout for a large install base
Example Prompts
"How do I verify my app hasn't been tampered with?" "DCAppAttestService attestKey keeps failing with serverUnavailable" "How do I prevent users from claiming a free trial multiple times?" "What's the difference between attestation and assertion?" "How do I validate an attestation object on my server?" "isSupported returns false — should I block the user?" "We have 2M DAU, how do I roll out App Attest safely?" "How do I detect if someone is creating fake app instances?"
Red Flags
Signs you're headed for trouble:
- Validating app integrity on-device — Modified apps control the runtime. Any local check can be patched out. Verification MUST happen server-side.
- Not guarding with isSupported — DCAppAttestService crashes on unsupported devices. Always check before calling any API.
- Blocking users when isSupported returns false — Some legitimate devices return false. Treat as risk signal, not hard block.
- Reusing keys across multiple users on same device — One key per user per device. Shared keys break account-level trust association.
- Enabling App Attest for all users at once —
attestKeycalls Apple's servers. At scale, rate limiting causes failures. Gradual rollout required (WWDC 2021-10244). - Using assertions for every API call — Cryptographic cost per call. Reserve for sensitive operations (purchases, account changes), not routine fetches.
- Discarding key on serverUnavailable error — Transient Apple server issue. Retry with same key. Only discard on other errors.
- Skipping counter validation on server — Counter must be ever-increasing. Without this, replay attacks succeed.
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 · 336 lines · 63 tokens per session scan A 303e257bfa9b
axiom-app-attest is a skill published in the GitHub repository ComeOnOliver/skillshub (63 stars, last pushed 2mo ago), licensed MIT. It adds 63 tokens to every session and 3,593 once invoked, about $0.0003 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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