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 agentmods add skills/cratis/ai/cratis-vertical-slicenpx skills add Cratis/AI --skill cratis-vertical-slicegit 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-vertical-slice)<a href="https://agentmods.dev/skills/cratis/ai/cratis-vertical-slice"><img src="https://agentmods.dev/badge/skills/cratis/ai/cratis-vertical-slice.svg" alt="Measured on agentmods" 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 | $0.00089 | $0.01566 |
| Opus 5 | $0.00044 | $0.00783 |
| Sonnet 5 | $0.00018 | $0.00313 |
| Haiku 4.5 | $0.00009 | $0.00157 |
Grade A, and why
cratis-vertical-slice 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 4d 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- cratis-vertical-slice — 100% identical, 4 lines differ
How it starts
The opening of the file, as written. The whole thing — 208 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Core principle
A vertical slice contains everything for a single behavior: the command or query, the events it produces, the projections that build read models, the React component, and the specs. Everything lives together because everything changes together.
One feature folder → many slices.
One slice folder → one .cs file (all backend) + one .tsx file (frontend).
Step 1 — Identify the feature and slice type
First, name the feature (a domain noun, pluralized) and identify the slice type:
| Slice type | What it does | Key artifacts |
|---|---|---|
| State Change | Mutates system state | Command + events + validators/constraints |
| State View | Projects events into queryable data | Read model + projection + queries |
| Automation | Reacts to events, makes decisions | Reactor + optional local read models |
| Translation | Adapts events between slices | Reactor → triggers commands in own slice |
Step 2 — Create the folder structure
The feature folder lives directly under the app source root (or under an optional <Module>/ grouping) — there is no top-level Features/ wrapper.
<Feature>/ ← feature root (pluralized domain noun)
├── <Feature>.tsx ← composition page
├── <ConceptName>.cs ← shared ConceptAs<T> / EventSourceId<T> types for the feature
└── <SliceName>/ ← slice (action or view name) — the invariant unit
├── <SliceName>.cs ← ALL backend artifacts in ONE file
├── <Component>.tsx ← React component
└── when_<behavior>/ ← specs
└── and_<scenario>.cs
✅ Correct:
Authors/
├── Authors.tsx
├── AuthorId.cs
├── AuthorName.cs
├── Registration/
│ ├── Registration.cs ← command + event + constraint + validator
│ ├── AddAuthor.tsx
│ └── when_registering/
│ └── and_there_are_no_authors.cs
└── Listing/
├── Listing.cs ← read model + projection + query
└── Listing.tsx
What ships with it
4 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.
- 4d ago First seen · 208 lines · 89 tokens per session scan A a5d90be9cfc3
cratis-vertical-slice is a skill published in the GitHub repository Cratis/AI (2 stars, last pushed yesterday), licensed MIT. It adds 89 tokens to every session and 1,566 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 2026-08-31.
Other skills, from other repositories
add-reactor
Use this skill when asked to add a Chronicle reactor (automation or translation) to a Cratis-based project. Reactors observe events and produce side effects.
cratis-vertical-slice
Explains how vertical feature slices are structured in a Cratis Chronicle + Arc application — folder layout, the single backend .cs file, the four slice types (State Change/View/Automation/Translation), and how features compose slices. Use when asking how slices work, where files go, or which slice type to choose. To…
create-event-model
Create and maintain Mermaid eventmodeling diagrams (EventModel.md) for a Cratis module or feature. Use when adding, renaming, moving, or deleting modules/features/slices, commands, events, read models, automations, translations, or cross-module event flows — to keep the diagram in sync with the code.
event-modeling
Design a Cratis event model before writing code — decide stream boundaries, commands, events, read models, automations/translations, compliance subjects, and the spec outline. Use this when behavior, event vocabulary, stream boundaries, or a multi-slice flow is not yet settled, before implementing a slice.
ship-changes
Ship staged or unstaged local changes: create a branch, make logical commits, push to origin, open a PR with the correct description and label, merge it, close the issues it resolves, and delete the branch locally and on origin. Use whenever the user asks to commit, push, create a PR, ship, or land changes.
add-concept
Use this skill when asked to create a strongly-typed domain identifier or value (such as ProjectId, AuthorName, InvoiceNumber) in a Cratis-based project. Produces a ConceptAs record with the correct conversions and sentinel values.