Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/constellos/claude-codenpx agentmods add skills/constellos/claude-code/feature-sliced-designWrote 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/constellos/claude-code/feature-sliced-design)<a href="https://agentmods.dev/skills/constellos/claude-code/feature-sliced-design"><img src="https://agentmods.dev/badge/skills/constellos/claude-code/feature-sliced-design/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/constellos/claude-code/feature-sliced-design"><img src="https://agentmods.dev/badge/skills/constellos/claude-code/feature-sliced-design.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 | $0.08498 |
| Opus 5.5 | $0.00054 | $0.03399 |
| Sonnet 5.5 | $0.00027 | $0.01700 |
| Haiku 4.5 | $0.00013 | $0.00850 |
Grade C, and why
Feature-Sliced Design scanned grade C with 2 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 1mo 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.
Recursive force deletehighDestructive command
rm -rf with a variable or a broad path is one typo away from removing the wrong tree.
1. Clear `.next` directory: `rm -rf .next` Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
export const apiClient = axios.create({ How it starts
The opening of the file, as written. The whole thing — 1,310 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Feature-Sliced Design
Purpose
Feature-Sliced Design (FSD) is an architectural methodology for organizing frontend applications into a standardized, scalable structure. It provides clear separation of concerns through a layered hierarchy that prevents circular dependencies and promotes maintainability.
Why use FSD:
- Scalability: Grows naturally as your application expands
- Maintainability: Clear boundaries make refactoring safer
- Team collaboration: Consistent structure enables parallel development
- Onboarding: New developers understand architecture quickly
Custom 'views' layer:
This skill uses 'views' instead of the standard FSD 'pages' layer to avoid confusion with Next.js App Router's /app directory. The /app directory handles routing only (minimal logic), while /src/views contains your actual page business logic.
Next.js integration:
FSD works seamlessly with Next.js App Router by separating routing concerns (in /app) from business logic (in /src/views and other FSD layers). This keeps your routing configuration clean while maintaining FSD's architectural benefits.
When to Use
Apply Feature-Sliced Design when:
- Starting new Next.js projects that require clear architectural boundaries
- Refactoring growing codebases that lack consistent structure
- Working with multi-developer teams needing standardized organization
- Building applications with complex business logic requiring separation of concerns
- Developing Turborepo monorepo applications where each app needs independent FSD structure
- Scaling applications where circular dependencies become problematic
- Creating enterprise applications with long-term maintenance requirements
Core Principles
Layer Hierarchy
FSD organizes code into 7 standardized layers (from highest to lowest):
- app - Application initialization, global providers, routing configuration
- processes - Deprecated (functionality moved to features and app)
- views - Page-level business logic (custom naming, replaces standard 'pages')
- widgets - Large composite UI blocks that span multiple features
- features - User-facing interactions with business value
- entities - Business domain objects and models
- shared - Reusable utilities, UI kit, third-party integrations
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.
- 1mo ago First seen · 1,310 lines · 134 tokens per session scan C f64844128436
Feature-Sliced Design is a skill published in the GitHub repository constellos/claude-code (5 stars, last pushed 1mo ago), licensed MIT. It adds 134 tokens to every session and 8,498 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it C with 2 findings (recursive force delete, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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