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-application-slice-specificationsgit 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-application-slice-specifications)<a href="https://agentmods.dev/skills/cratis/ai/cratis-application-slice-specifications"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-application-slice-specifications/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-application-slice-specifications"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-application-slice-specifications.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 | $0.00041 | $0.03660 |
| Opus 5.5 | $0.00016 | $0.01464 |
| Sonnet 5.5 | $0.00008 | $0.00732 |
| Haiku 4.5 | $0.00004 | $0.00366 |
Grade A, and why
cratis-application-slice-specifications 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 today.
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 — 292 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Cratis application slice specifications
Start a pure decision with a plain method call: Handle(),
Handle(providedValue), reducer logic or a reactor's decision needs no host,
services or harness. Add a scenario where the pipeline, validation,
authorization, constraints or projections contribute proof. The scenario family
exercises the real Arc and Chronicle code paths in-process — no HTTP, no fixture,
no server.
This skill decides when to add a scenario and what to cover. The C# mechanics
(Establish/Because, substitutes, contexts) live in
cratis-specifications-csharp.
Product packages
| Package | Purpose |
|---|---|
Cratis.Arc.Testing |
CommandScenario<TCommand> and the CommandResult assertions |
Cratis.Arc.Chronicle.Testing |
Given, EventLog, AppendedEvents and the appended-event assertions on a command scenario |
Cratis.Chronicle.Testing |
EventScenario, ReadModelScenario<T>, ReactorScenario<T> |
Cratis.Specifications.XUnit |
The Specification base and the ShouldXxx assertions |
Reactor read-model setup and the EventContext.From UTC default below need a newer Chronicle than
the Arc scenario surface itself; see cratis-chronicle-reactor/references/specifications.md for sources.
Requires Chronicle 19.46.0 or later for class-based reactor read-model seeding and the EventContext.From UTC default.
Cratis.Testing is the meta-package that brings Cratis.Arc.Testing and
Cratis.Arc.Chronicle.Testing together. Reverify against the owning product
repository before claiming support for another version.
Route near misses
- The repository builds a Cratis library rather than an application: use
cratis-specifications-csharpand stay on the plainSpecificationbase. - React, TypeScript, or a view model: use
cratis-application-react-specifications. - The subject is append semantics or a constraint on its own: use
cratis-chronicle-event-specifications. - The subject is a projection or reducer on its own: use
cratis-chronicle-read-model-specifications. - The question is what the slice should do: settle the behavior first. A specification records a decision; it does not make one.
- The scope is model-first (the
specificationblocks of the.playslice are the contract for this skill). Decide this with the decision rule incratis-screenplay-modeling-lifecycle: model-first only when an accepted model under the model root covers this scope, or the repository is opted in (opted in pergeneral.md"Model first"; wherecratis-screenplay-modeling-lifecycleis installed, run itsscripts/model-first-status.mjs); framework, infrastructure, client, adapter and not-opted-in brownfield work stays code-first. Opted in but no model for this scope: model it first (cratis-screenplay-discovery, thencratis-screenplay-slice-design) before writing specifications. If those Screenplay skills are not installed, say so and stop; never author.playfrom memory. Never edit Stage-managed output, and never change a model specification to match existing code. Author or change model specifications withcratis-screenplay-specificationsandcratis-screenplay-scenario-coverage; check finished code against the model withcratis-application-slice-conformance.
What ships with it
5 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.
- today Changed · -85 tokens per session ba9406ecd23a
- 9d ago Changed · +27 tokens per session 69967e832d7b
- 10d ago Changed · +1 lines d93ec9967d48
- 11d ago Changed · -2 lines 21566b9bbdcc
- 13d ago Changed · -28 lines d8b98852a77f
- 14d ago Changed · +10 lines 7cf8f6d7bfbe
- 15d ago Changed · +13 lines fee41a3508ae
- 18d ago Changed 10f37e28c857
- 20d ago Changed · +65 lines · +12 tokens per session 4f5f2211f555
- 27d ago First seen · 233 lines · 87 tokens per session scan A 5b9f691dbc98
cratis-application-slice-specifications is a skill published in the GitHub repository Cratis/AI (4 stars, last pushed yesterday), licensed MIT. It adds 41 tokens to every session and 3,660 once invoked, about $0.0002 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 2026-09-08.
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