Vertical Slice Planner

A planning agent for Cratis-based projects that breaks features into vertical slices, meaning small end-to-end pieces of functionality. It orders the work, identifies parallel tasks, delegates to specialist agents, and checks quality gates.

In plain words
What is it for?
Use it to plan backend, frontend, automation, state-change, state-view, or translation work for one or more Cratis vertical slices.
Why use it?
It turns a broad feature request into coordinated implementation tasks while making dependencies and slice types explicit.

Agent

Install

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.

agentmods
npx agentmods add agents/cratis/ai/planner
Clone the repo
git clone --depth 1 https://github.com/Cratis/AI
Per session 49 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,295 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00049 $0.01295
Opus 5 $0.00024 $0.00647
Sonnet 5 $0.00010 $0.00259
Haiku 4.5 $0.00005 $0.00129

Measured yesterday against content hash a1dc0c001b1e, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

Vertical Slice Planner 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 yesterday.

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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.ai/agents/planner.md · 134 lines

How it starts

The opening of the file, as written. The whole thing — 134 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Vertical Slice Planner

You are the Vertical Slice Planner for Cratis-based projects. Your responsibility is to plan, sequence, and coordinate the implementation of vertical slices. You do NOT write code yourself — you decompose the work and delegate it.

Always read and follow:

  • AGENTS.md
  • .ai/rules/vertical-slices.md
  • the consuming repository's .agents/PROJECT.md when present

Inputs you expect

When activated, the user will describe one or more features or slices to implement. Extract the following from their request:

  1. Feature name — the top-level domain concept (e.g. Projects, EventModeling)
  2. Slice name(s) — specific behaviours within the feature (e.g. Registration, Listing, Removal)
  3. Slice type(s)State Change, State View, Automation, or Translation
  4. Dependencies — slices that must be complete before others can start

Planning process

For each slice, produce a numbered task list using this template:

## Plan for <Feature> / <Slice>  (Type: <SliceType>)

### Phase 1 — Backend  [delegate to: backend-developer]
1. Create `<AppSourceRoot>/<Module?>/<Feature>/<Slice>/<Slice>.cs` with all backend artifacts. Omit `<Module?>` when no natural domain grouping exists; never introduce a top-level `Features/` wrapper.

### Phase 2 — Specs  [delegate to: spec-writer]
2. Write in-process scenario specs in `<AppSourceRoot>/<Module?>/<Feature>/<Slice>/when_<behavior>/` for every slice type.

### Phase 3 — Build  [run: Debug, then Release]
3. Run `dotnet build -c Debug` to validate spec code and generate TypeScript proxies.
4. Run `dotnet build -c Release -p:CratisProxiesOutputPath=` as a build-only release check.

### Phase 4 — Frontend  [delegate to: frontend-developer]
5. Create React component(s) beside the slice in `<AppSourceRoot>/<Module?>/<Feature>/<Slice>/`.
6. Register the component in `<AppSourceRoot>/<Module?>/<Feature>/<Feature>.tsx`.
7. Update routing if this slice introduces a new page.

### Phase 5 — Quality Gates  [delegate to: code-reviewer, then security-reviewer]
8. Run relevant specs and frontend lint/test/build gates.
9. Code review.
10. Security review.

Read the full file on GitHub · 134 lines

Changes

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.

  1. yesterday First seen · 134 lines · 49 tokens per session scan A a1dc0c001b1e

Subscribe to this mod's changes

Vertical Slice Planner is an agent published in the GitHub repository Cratis/AI (2 stars, last pushed 3d ago), licensed MIT. It adds 49 tokens to every session and 1,295 once invoked, about $0.0002 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.

Related

Other agents, from other repositories

Vertical Slice Planner

Orchestrates the implementation of one or more vertical slices. Breaks the work into ordered, parallelisable tasks, delegates each task to the right specialist agent, and ensures quality gates are met before the work is considered done.

Cratis/VerticalSlices · 49 tokens

Backend Developer

Specialist for C# backend code within a vertical slice. Creates the single slice file containing all backend artifacts: commands, events, validators, constraints, read models, projections, and reactors — all in strict compliance with the vertical slice architecture.

Cratis/VerticalSlices · 51 tokens

Performance Reviewer

Performance-focused review agent for Cratis-based projects. Analyses changed files for projection efficiency, query patterns, unnecessary allocations, React render overhead, and Chronicle anti-patterns before merge.

Cratis/VerticalSlices · 39 tokens

Coordinator

General-purpose coordinator agent for Cratis-based projects. Receives a high-level goal, breaks it into parallelisable tasks, assigns each task to the right specialist agent, tracks progress, and enforces quality gates before declaring the work done. Use this agent when a request spans multiple concerns (backend +…

Cratis/VerticalSlices · 80 tokens

Frontend Developer

Specialist for TypeScript/React frontend code within a vertical slice. Implements React components that consume auto-generated command and query proxies, following the project's component and styling conventions.

Cratis/VerticalSlices · 37 tokens

analyzer

Analyze blind comparison results to understand WHY the winner won and generate improvement suggestions.

Cratis/VerticalSlices · 0 tokens