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 Cratis/AI --skill cratis-arc-authentication-authorization-and-identitygit clone --depth 1 https://github.com/Cratis/AIWrote 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/cratis/ai/cratis-arc-authentication-authorization-and-identity)<a href="https://agentmods.dev/skills/cratis/ai/cratis-arc-authentication-authorization-and-identity"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-arc-authentication-authorization-and-identity/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/cratis/ai/cratis-arc-authentication-authorization-and-identity"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-arc-authentication-authorization-and-identity.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 | $0.00107 | $0.02532 |
| Opus 5 | $0.00053 | $0.01266 |
| Sonnet 5 | $0.00021 | $0.00506 |
| Haiku 4.5 | $0.00011 | $0.00253 |
Grade A, and why
cratis-arc-authentication-authorization-and-identity 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 2d 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 — 234 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Authentication, authorization and identity in Arc
Arc separates three things that are easy to conflate: authentication decides who the caller is, authorization decides whether that caller may run this command or query, and the identity provider decides what the frontend is told about them. Each has its own extension point.
Verified product sources
| Package | Version | Purpose |
|---|---|---|
Cratis.Arc.Core |
22.10.4 |
Cratis.Arc.Identity, Cratis.Arc.Authorization, Cratis.Arc.Authentication, Cratis.Arc.Tenancy |
Cratis.Arc |
22.10.4 |
ASP.NET Core hosting, AddMicrosoftIdentityPlatformIdentityAuthentication |
@cratis/arc |
22.10.4 |
IdentityProvider, IIdentity |
@cratis/arc.react |
22.10.4 |
IdentityProvider component, useIdentity, RequireRole |
Reverify before claiming support for another version.
Read this first: what is and is not trusted
Arc's shipped authentication reads a forwarded principal from HTTP headers.
x-ms-client-principal is base64, not a signature, and Arc does not check
who sent it. Any caller that can reach the application can author the entire
serialized principal.
That is not a defect — it is the EasyAuth/reverse-proxy model, where the ingress is the trust boundary. But it means:
- the application must be unreachable except through the ingress that sets those headers;
- nothing Arc gives you makes the forwarded values authentic;
- Arc ships no OpenID Connect and no JWT bearer integration. If you need the application itself to validate a token, that is ordinary ASP.NET Core authentication you configure yourself.
Identity details — what the frontend is told
Implement IProvideIdentityDetails to shape what /.cratis/me returns:
using Cratis.Arc.Identity;
public class <Name>IdentityDetailsProvider : IProvideIdentityDetails<<Details>>
{
public async Task<IdentityDetails> Provide(IdentityProviderContext context)
{
// context.Id, context.Name, context.Claims
return new IdentityDetails(<isAuthorized>, new <Details>(<...>));
}
}
What ships with it
6 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.
- 2d ago First seen · 234 lines · 107 tokens per session scan A ecc33a5d4e9c
cratis-arc-authentication-authorization-and-identity is a skill published in the GitHub repository Cratis/AI (2 stars, last pushed yesterday), licensed MIT. It adds 107 tokens to every session and 2,532 once invoked, about $0.0005 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.
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