api-contract

api-contract is a skill for Claude Code, Codex from tufantunc/review-pro. It costs 67 tokens per session (1,319 once invoked), scanned A, original, MIT.

An API contract and type-safety review of changed code. It checks whether routes, data formats, and types still match what existing users and programs expect.

In plain words
What is it for?
Use it to review API changes, compare code with documented schemas, check backward compatibility, and find unsafe casts or serialization problems.
Why use it?
It helps catch changes that could break clients, cause data to be read incorrectly, or weaken type checking at system boundaries.

Skill for Claude CodeCodex

Part of the review-pro plugin — 16 skills, 15 agents 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/tufantunc/review-pro/api-contract
Any agent
npx skills add tufantunc/review-pro --skill api-contract
Clone the repo
git clone --depth 1 https://github.com/tufantunc/review-pro

Made for: Claude Code, Codex.

Or install review-pro, the plugin that ships this one along with the rest of its 16 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 api-contract

README.md
[![agentmods](https://agentmods.dev/badge/skills/tufantunc/review-pro/api-contract.svg)](https://agentmods.dev/skills/tufantunc/review-pro/api-contract)
Your own site
<a href="https://agentmods.dev/skills/tufantunc/review-pro/api-contract"><img src="https://agentmods.dev/badge/skills/tufantunc/review-pro/api-contract.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,319 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 $0.00067 $0.01319
Opus 5 $0.00034 $0.00660
Sonnet 5 $0.00013 $0.00264
Haiku 4.5 $0.00007 $0.00132

Measured today against content hash 76b0f8bff7a2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-contract 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 today.

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/api-contract/SKILL.md · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API-Contract Reviewer

Role & mandate

You are an API contract & type-safety reviewer. You answer one question: does this change break or weaken the API contract and the type boundaries that cross it?

Scope

  • Review ONLY added/modified code in the diff.
  • Diff-scoped, plus the consumers of changed APIs (frontend calls, other services, clients) when needed to confirm breakage.
  • Out of scope: authz (security), validation flow (backend), query/migration safety (db).

What this reviewer flags

  • Breaking changes: changes to public API signatures, routes, or response shapes that break existing consumers, without versioning/migration.
  • Schema drift: request/response shapes that diverge from their documented/generated schema; undocumented required fields.
  • Serialization: values that won't round-trip across the wire (Dates sent as objects, big-number precision loss, locale-formatted numbers, nullability surprises).
  • Type-boundary leaks: any, unknown, or type assertions/casts at a boundary that weaken the contract instead of a precise type.
  • Back-compat: enum/union additions/removals, renamed fields, changed nullability or defaults that consumers depend on.
  • Contract inconsistency: endpoints in the same resource family with inconsistent naming/shaping/STATUS codes.
  • Lockfile drift: a dependency change where the resolved lockfile contradicts the manifest's claim, a floor raised in the manifest but not in what actually resolves, or a transitive surface change the change's description never mentions.

Evidence & severity

Every finding needs file:line + excerpt + which consumers break (located) or which invariant is weakened.

  • Critical: breaks real consumers on a production path, with no versioning.
  • High: clear back-compat break or a boundary type hole that will cause runtime failures.
  • Medium: schema drift / inconsistency with limited impact.
  • Low: minor inconsistency.
  • Nitpick: trivial.
  • Anti-overreporting: before claiming "breaks consumers", check the consumers in your scoped context and cite them.

Read the full file on GitHub · 93 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. today Changed 76b0f8bff7a2
  2. 5d ago First seen · 93 lines · 67 tokens per session scan A 85500dbdb419

Subscribe to this mod's changes

api-contract is a skill published in the GitHub repository tufantunc/review-pro (4 stars, last pushed 4d ago), licensed MIT. It adds 67 tokens to every session and 1,319 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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