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-validation-typescriptgit 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-validation-typescript)<a href="https://agentmods.dev/skills/cratis/ai/cratis-arc-validation-typescript"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-arc-validation-typescript/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-validation-typescript"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-arc-validation-typescript.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 | $0.00134 | $0.03802 |
| Opus 5.5 | $0.00054 | $0.01521 |
| Sonnet 5.5 | $0.00027 | $0.00760 |
| Haiku 4.5 | $0.00013 | $0.00380 |
Grade A, and why
cratis-arc-validation-typescript 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 3d 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 — 326 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Validate an Arc command or query in TypeScript (Node.js server)
A rule in Arc for TypeScript lives where the information it needs is available,
and as early as that allows. Validators run before handle() and also answer on
the command's POST <route>/validate, so a form can ask before the user
submits. Every rejection comes back as a ValidationResult with a message and
the member it concerns — never as a thrown error.
Arc for TypeScript is a source preview: @cratis/arc.core and the other
server packages are not published to npm, and the API may change. The published
@cratis/arc client is separate; it runs the client-safe rules the proxy
generator copies into generated proxies. Setup is in
cratis-arc-command-typescript.
Verified product sources
Source: Cratis/Arc.TypeScript (source preview;
server packages not on npm), reading Source/Core/validation/** (including
index.ts, ValidationResult.ts, Severity.ts, RuleBuilder.ts),
Source/Core/commands/Outcome.ts, Documentation/commands/command-validation.md,
validation-severity-filtering.md, command-outcomes.md,
Documentation/queries/validation.md, Documentation/concepts.md,
Documentation/proxy-generation/validation.md, Source/Testing, and the
Samples/Tasks validators.
ValidationResult is both the exported interface and a value with the helpers
ValidationResult.information/warning/error(message, options?); the positional
validation(...) function remains available.
Choose where to reject
| The decision depends on | Put it in | Runs on /validate |
Caller sees |
|---|---|---|---|
| The request's shape: types, required/optional fields | @field plus @optional()/@nullable()/@defaultValue() |
Yes | 400 malformedRequest, no message or members |
| Who is calling | @roles, @authorize, a policy |
Yes | 401 or 403 |
| One value, wherever it appears | ConceptValidator on the concept |
Yes | 400 with your message and member |
| The command's own fields, or a service | CommandValidator |
Yes | 400 with your message and member |
| Stored state for the command's key | CommandValidator rule calling readModelForValidation |
Yes | 400 with your message and member |
| Data you load anyway to do the work | provide() returning rejected(...) or denied(...) |
No | 400 or 403 |
| A decision only the handler can make | handle() returning rejected(...) or denied(...) |
No | 400 or 403 |
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.
- 3d ago Changed · -32 tokens per session 1f48240aeaa9
- 7d ago Changed 49f93ba03655
- 9d ago Changed · +2 lines 0ef1f7d2def5
- 15d ago Changed · +3 lines d3e47775d32b
- 20d ago First seen · 321 lines · 166 tokens per session scan A f7e14c99ee2f
cratis-arc-validation-typescript is a skill published in the GitHub repository Cratis/AI (4 stars, last pushed yesterday), licensed MIT. It adds 134 tokens to every session and 3,802 once invoked, about $0.0005 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 2026-10-02.
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