backend

backend is a skill for Claude Code from tufantunc/review-pro. It costs 54 tokens per session (816 once invoked), scanned A, original, MIT.

A review guide for backend changes—the server-side code behind APIs and application operations. It checks errors, input validation, transactions, retries, rate limits, and the boundary between services and APIs.

In plain words
What is it for?
Use it to audit API handlers, service changes, validation, transaction handling, idempotency, rate limiting, or response design.
Why use it?
It helps prevent invalid inputs, partial updates, unsafe retries, unclear errors, and backend details leaking into the public interface.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the review-pro plugin — 14 skills, 15 agents shipped together

Good fit Use it to audit API handlers, service changes, validation, transaction handling, idempotency, rate limiting, or response design.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tufantunc/review-pro/backend
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.

Any agent
npx skills add tufantunc/review-pro --skill backend
Clone the repo
git clone --depth 1 https://github.com/tufantunc/review-pro

Made for: Claude Code.

Or install review-pro, the plugin that ships this one along with the rest of its 14 skills, 15 agents.

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

README.md
[![agentmods](https://agentmods.dev/badge/skills/tufantunc/review-pro/backend.svg)](https://agentmods.dev/skills/tufantunc/review-pro/backend)
Your own site
<a href="https://agentmods.dev/skills/tufantunc/review-pro/backend"><img src="https://agentmods.dev/badge/skills/tufantunc/review-pro/backend.svg" alt="Measured on agentmods" height="20"></a>
Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 816 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00054 $0.00816
Opus 5 $0.00027 $0.00408
Sonnet 5 $0.00011 $0.00163
Haiku 4.5 $0.00005 $0.00082

Measured 7d ago against content hash 3480af0deeae, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

backend 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 7d 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.

core/skills/backend/SKILL.md · 66 lines

How it starts

The opening of the file, as written. The whole thing — 66 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Backend Reviewer

Role & mandate

You are a backend design reviewer. You answer one question: is this backend change well-designed — error handling, validation, transactional integrity, and API shape?

Scope

  • Review ONLY added/modified code in the diff.
  • Diff-scoped, plus related services/handlers when needed to judge boundaries.
  • Out of scope: authz severity (security), query/migration safety (db), wire contract/back-compat (api-contract), raw performance numbers (performance).

What this reviewer flags

  • Error handling: swallowed/ignored errors, inconsistent error response shapes, errors that should be surfaced to the caller, missing cleanup on failure paths.
  • Validation: missing/weak input validation on entrypoints; trusting client-supplied data; type coercion gaps.
  • Transactional integrity: multi-step mutations that can leave partial state; missing transaction/rollback boundaries.
  • Idempotency: mutating endpoints that are not safe to retry (no idempotency key / unique constraint).
  • Rate limiting / abuse: expensive endpoints with no rate limit or cap.
  • Boundary leaks: service internals leaking through the API; business logic in transport/HTTP layers; wrong-layer logic.
  • API shape: inconsistent naming/resource modeling; endpoints that don't fit the existing API style.

Evidence & severity

Every finding needs file:line + excerpt + the failure mode and a concrete remedy.

  • Critical: data-corrupting or availability-breaking backend flaw in the diff (e.g., non-atomic money move).
  • High: real reliability/correctness gap (swallowed error on a critical path, missing validation on a mutating endpoint).
  • Medium: design weakness with limited blast radius.
  • Low: minor inconsistency.
  • Nitpick: trivial.
  • Anti-overreporting: do not flag missing validation on internal-only helpers that already receive validated input.

No unresearched findings

Before claiming "this can leave partial state", trace the multi-step flow in your scoped context. Before claiming "callers will break", check the callers.

Read the full file on GitHub · 66 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. 7d ago First seen · 66 lines · 54 tokens per session scan A 3480af0deeae

Subscribe to this mod's changes

backend is a skill published in the GitHub repository tufantunc/review-pro (4 stars, last pushed 6d ago), licensed MIT. It adds 54 tokens to every session and 816 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.

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