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/new-vertical-slicenpx skills add Cratis/AI --skill new-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/new-vertical-slice)<a href="https://agentmods.dev/skills/cratis/ai/new-vertical-slice"><img src="https://agentmods.dev/badge/skills/cratis/ai/new-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 | $0.00057 | $0.01271 |
| Opus 5 | $0.00028 | $0.00635 |
| Sonnet 5 | $0.00011 | $0.00254 |
| Haiku 4.5 | $0.00006 | $0.00127 |
Grade A, and why
new-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 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.
Copies of this mod
1 near-identical copy found in the catalogue:
- new-vertical-slice — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 104 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Implement a complete vertical slice following this EXACT order. Never skip steps or work on multiple slices in parallel.
Step 1 — Identify the slice type
Choose one of:
- State Change — a command that mutates state and records events (most common)
- State View — a query that reads from a read model
- Automation — a background reactor triggered by events
- Translation — transforms events into other events
Step 2 — Determine the namespace root
Read global.json and existing .cs files under the app source root to find the namespace root (e.g. Studio, Library). Never hard-code it.
Step 3 — Create the C# slice file
Place ALL backend artifacts in a single file in the slice folder: <Feature>/<Slice>/<Slice>.cs (under the app source root; a <Module>/ grouping above the feature is optional — there is no top-level Features/ wrapper).
File creation order within the slice:
- Concept types (if new strongly-typed IDs are needed — see
add-conceptskill) - Command
recordwithHandle()method and optional validation attributes- If a business rule depends on Chronicle event-sourced state, add the relevant read model as a parameter to
Handle()— seeadd-business-ruleskill (DCB pattern)
- If a business rule depends on Chronicle event-sourced state, add the relevant read model as a parameter to
CommandValidator<T>for command-level rejection rules (seeadd-business-rule);ConceptValidator<T>for value invariants- Constraint class
<Name>Constraint(if needed) - Event
recordwith[EventType](no arguments, no mutable properties) - Read model
recordwith[ReadModel]and model-bound projection attributes ([FromEvent<T>],[Key], etc.)- Use fluent
IProjectionFor<T>only when model-bound attributes don't fit
- Use fluent
Critical rules:
- Commands are
recordtypes with aHandle()method directly on them — DO NOT create separate handler classes - Events use
[EventType]with NO arguments — never pass a GUID or string - Projection: prefer model-bound attributes on the read model; if using
IProjectionFor<T>, AutoMap is on by default — just call.From<>()directly - Namespace mirrors the folder path under the source root:
<RootNamespace>.<Module>.<Feature>.<Slice>(noFeaturessegment — drop any level that isn't present) - Copyright header on every file:
// Copyright (c) Cratis. All rights reserved. // Licensed under the MIT license. See LICENSE file in the project root for full license information.
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 First seen · 104 lines · 57 tokens per session scan A 657c4b0d399a
new-vertical-slice is a skill published in the GitHub repository Cratis/AI (2 stars, last pushed today), licensed MIT. It adds 57 tokens to every session and 1,271 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 2026-08-31.
Other skills, from other repositories
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.
skill-creator
Create new skills, modify and improve existing skills, and measure skill performance. Use when users want to create a skill from scratch, update or optimize an existing skill, run evals to test a skill, benchmark skill performance with variance analysis, or optimize a skill's description for better triggering accuracy.
cratis-command
Step-by-step guidance for creating a Cratis Arc command — [Command] record, Handle() method, CommandValidator, proxy generation, and React .use() hook with CommandDialog. Use when adding or creating a command, wiring up a form or button to the backend, working with IEventLog, CommandResult, CommandValidator…
cratis-readmodel
Step-by-step guidance for creating a Cratis Chronicle read model from scratch — defining events, choosing between projection and reducer, [ReadModel] record with static query methods, and the generated TypeScript proxy in React. Use when creating a read model, working with [EventType], [ReadModel], IProjectionFor…
add-traces
Use this skill when asked to add OpenTelemetry tracing to a class in a Cratis Chronicle Kernel project. Produces Traces.cs companion files using the [Span] source-generator pattern from Cratis.Traces, registers IActivitySource as a keyed DI service, and injects it into the target class.