go-api-contract

go-api-contract is a skill for Claude Code, Codex from Dankosik/go-service-template-rest. It costs 32 tokens per session (344 once invoked), scanned A, original, MIT.

A guide for checking the observable behavior of a REST API, meaning everything a client can detect from requests and responses. REST APIs are web interfaces that other programs use to exchange data.

In plain words
What is it for?
Use it when changing published API operations and you need to compare old and new client-visible behavior, including failures, replays, and recovery.
Why use it?
It reveals compatibility breaks that a valid schema check can miss, such as changed status codes, response bodies, errors, pagination, retries, or resource identity.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it when changing published API operations and you need to compare old and new client-visible behavior, including failures, replays, and recovery.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/dankosik/go-service-template-rest/go-api-contract
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 Dankosik/go-service-template-rest --skill go-api-contract
Clone the repo
git clone --depth 1 https://github.com/Dankosik/go-service-template-rest

Made for: Claude Code, Codex.

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 go-api-contract

README.md
[![agentmods](https://agentmods.dev/badge/skills/dankosik/go-service-template-rest/go-api-contract/github.svg)](https://agentmods.dev/skills/dankosik/go-service-template-rest/go-api-contract)
Your own site
<a href="https://agentmods.dev/skills/dankosik/go-service-template-rest/go-api-contract"><img src="https://agentmods.dev/badge/skills/dankosik/go-service-template-rest/go-api-contract/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.

agentmods 80×15 button for go-api-contract

Your own site · 80×15
<a href="https://agentmods.dev/skills/dankosik/go-service-template-rest/go-api-contract"><img src="https://agentmods.dev/badge/skills/dankosik/go-service-template-rest/go-api-contract.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 344 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 $0.00032 $0.00344
Opus 5 $0.00016 $0.00172
Sonnet 5 $0.00006 $0.00069
Haiku 4.5 $0.00003 $0.00034

Measured 2d ago against content hash 687814e94b08, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

go-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 2d 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.

.agents/skills/go-api-contract/SKILL.md · 38 lines

What it actually says

Go API Contract

A public API is an observable contract: every distinction a deployed client can detect is a clause.

request acceptance -> success -> failure -> replay or async recovery -> compatibility -> proof

For a delegated Decision or Review, or when the active artifact requires its result interface, load the shared specialist contract. For each affected operation, build one ObservableCell{surface, old, accepted, client_consequence, owner, proof} matrix from api/openapi/service.yaml, the serving router, internal/problem, and affected consumers. Each changed cell names the old behavior, accepted behavior, client consequence, canonical owner, and proof.

Status, body shape or absence, error code and details, default and nullability, pagination order and cursor, resource identity, retry outcome, and unknown mutation outcome are observables. A green schema diff proves syntax, not compatibility.

A Decision fills every missing cell and its migration behavior. A Review tries to falsify every accepted cell through a client-visible example. Complete only when every changed observable has one stable clause and consumer-runnable proof or a named evidence gap.

The scope starts at the changed published operation and closes only after every terminal, replay, and unknown-outcome state that a client can distinguish. Load the reference selector only for its stated pressure.

Files

What ships with it

5 files 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. 2d ago Changed · +2 lines 687814e94b08
  2. 10d ago First seen · 36 lines · 32 tokens per session scan A aecc688fd93c

Subscribe to this mod's changes

go-api-contract is a skill published in the GitHub repository Dankosik/go-service-template-rest (7 stars, last pushed yesterday), licensed MIT. It adds 32 tokens to every session and 344 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.

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