backend-design

backend-design is a skill for Claude Code from xenitV1/claude-code-maestro. It costs 24 tokens per session (2,176 once invoked), scanned A, original, MIT.

A set of backend development rules covering how server code is organised, secured, tested, and designed for reliable API performance.

In plain words
What is it for?
Use it when designing backend features, APIs, business logic, tests, and project structure.
Why use it?
It helps prevent fragile server code by requiring attention to security, edge cases, data problems, and competing requests.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the maestro plugin — 13 skills, 1 command, 1 agent, 7 hooks, 1 MCP server shipped together

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 skills/xenitv1/claude-code-maestro/backend-design
Any agent
npx skills add xenitV1/claude-code-maestro --skill backend-design
Clone the repo
git clone --depth 1 https://github.com/xenitV1/claude-code-maestro

Made for: Claude Code.

Or install maestro, the plugin that ships this one along with the rest of its 13 skills, 1 command, 1 agent, 7 hooks, 1 MCP server.

Wrote 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.

agentmods badge for backend-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/xenitv1/claude-code-maestro/backend-design.svg)](https://agentmods.dev/skills/xenitv1/claude-code-maestro/backend-design)
Your own site
<a href="https://agentmods.dev/skills/xenitv1/claude-code-maestro/backend-design"><img src="https://agentmods.dev/badge/skills/xenitv1/claude-code-maestro/backend-design.svg" alt="Measured on agentmods" height="20"></a>
Per session 24 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,176 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 5.1 $0.00024 $0.02176
Opus 5 $0.00012 $0.01088
Sonnet 5 $0.00005 $0.00435
Haiku 4.5 $0.00002 $0.00218

Measured 6d ago against content hash 1696132e0581, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

backend-design 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 6d 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.

skills/backend-design/SKILL.md · 175 lines

How it starts

The opening of the file, as written. The whole thing — 175 lines — stays where its author put it; the contents beside it link to each section on GitHub.

<domain_overview>

Backend Design System

Philosophy: The Backend is the Fortress. Logic is Law. Latency is the Enemy. Core Principle: ISOLATE features. TRUST no one. SCALE linearly.

ANTI-HAPPY PATH MANDATE (CRITICAL): Never assume the ideal scenario. AI-generated code often fails by ignoring edge cases and failure modes. For every business logic slice, you MUST document and test at least three failure scenarios: Race Conditions, Data Integrity violations (e.g., unique constraint overlaps), and Boundary failures. Reject any implementation that only covers the 'Happy Path'. Engineering is the art of handling what shouldn't happen. </domain_overview>

<architectural_protocols>

🚀 ELITE TIER KNOWLEDGE (ARCHITECTURAL PROTOCOLS)

0. The "Vertical Slice" Law (The Anti-Layer Mandate)

CRITICAL: You are FORBIDDEN from creating "Horizontal Layers" (Controllers, Services, Repositories) as primary folders.

The "Feature-First" Protocol: Code must be organized by BUSINESS CAPABILITY, not technical role.

  1. The Slice: A single directory (e.g., features/create-order/) contains EVERYTHING needed for that feature:
    • handler.ts (Controller)
    • logic.ts (Domain/Service)
    • schema.ts (DTO/Validation)
    • db.ts (Data Access)
  2. The Benefit: Changing a feature requires touching only ONE folder. No "Shotgun Surgery" across 5 layers.
  3. Shared Kernel: Only truly generic code (Logging, Auth Middleware, Database Connection) goes into shared/.

1. The "Modular Monolith" Mandate

  • Microservices Ban: Do NOT start with microservices. Start with a Modular Monolith.
  • Modulith Rules:
    • Modules must be isolated (like internal microservices).
    • Modules communicate via Events (Sub-Process or Message Bus), NEVER by importing another module's code directly.
    • The Outbox Pattern (Guaranteed Delivery):
      • Problem: If DB commit succeeds but Event Bus fails, the system is inconsistent.
      • Mandate: Write events to an outbox table in the SAME transaction as the data change.
      • Relay: A background worker pushes outbox entries to the Message Bus (RabbitMQ/Kafka).
    • Data Sovereignty: Module A cannot query Module B's tables. It must ask Module B via API/Event.

Read the full file on GitHub · 175 lines

Files

What ships with it

1 file 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.

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. 6d ago First seen · 175 lines · 24 tokens per session scan A 1696132e0581

Subscribe to this mod's changes

backend-design is a skill published in the GitHub repository xenitV1/claude-code-maestro (230 stars, last pushed 7mo ago), licensed MIT. It adds 24 tokens to every session and 2,176 once invoked, about $0.0001 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 2026-08-30.

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