What is apigen AGENTS.md?

Project instructions for apigen, a code generator that creates Go HTTP API code from OpenAPI specifications. OpenAPI is a format for describing how web APIs work, and the project includes Java, Go, examples, and tests.

It helps install dependencies, build the Java generator, regenerate Go examples and routes, and run the generated-code test suite.

It gives contributors the setup, build, generation, and test steps needed to change the generator without losing synchronisation between its parts.

How gemyago/apigen configures Codex and OpenCode

Reuse

Borrowing it

Nothing to install: this file belongs to gemyago/apigen. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/gemyago/apigen/main/AGENTS.md

Clone the repo

git clone --depth 1 https://github.com/gemyago/apigen

Made for: Codex, OpenCode.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/gemyago/apigen/agents-md/github.svg)](https://agentmods.dev/instructions/gemyago/apigen/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/gemyago/apigen/agents-md"><img src="https://agentmods.dev/badge/instructions/gemyago/apigen/agents-md/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/gemyago/apigen/agents-md"><img src="https://agentmods.dev/badge/instructions/gemyago/apigen/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,468 This file is loaded in full into every session.

When invoked 1,468 The same file — it is already loaded in full.

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.

Model	Per session	Once invoked
Fable 5.1	$0.01468	$0.01468
Opus 5.5	$0.00587	$0.00587
Sonnet 5.5	$0.00294	$0.00294
Haiku 4.5	$0.00147	$0.00147

Measured 1mo ago against content hash 4df3a9f8b1cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

apigen AGENTS.md 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 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.

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.md · 198 lines

How it starts

The opening of the file, as written. The whole thing — 198 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

This file is auto-generated and should be kept in sync with the project's build processes, dependencies, and conventions. Update this file whenever you modify the Makefile, CI workflows, or core development practices.

Project Overview

This is a code generator that creates HTTP API layer code for Go projects from OpenAPI specifications. The project is a monorepo containing:

/generators/go-apigen-server - Java-based OpenAPI Generator plugin (Maven project)
/lang/go/apigen - Go CLI tool for invoking the generator
/examples - Generated example projects (petstore, ping)
/tests/golang - Comprehensive test suite using generated code

Setup Commands

Install required dependencies and tools:

make deps

This installs all the necessary dependencies required to work locally.

Build Commands

Build the Java-based generator plugin:

mvn -f generators/go-apigen-server/pom.xml package

The output JAR is at generators/go-apigen-server/target/server.jar.

Regenerate all example code and test routes:

make generate/golang

This regenerates code in examples/ and tests/golang/routes using the latest generator.

Test Commands

Run full test suite with coverage:

make tests

Run only generated routes tests:

make tests/golang-generated-routes

Run only apigen CLI tests:

make tests/golang-apigen

Run tests for a specific package:

cd tests/golang && go test -v ./controllers/...

Linting

Run all linters:

make lint

This runs golangci-lint on:

lang/go/apigen
tests/golang
All example projects

Configuration is in .golangci.yml with strict settings (cyclomatic complexity max 30, exhaustive switch checks, etc.).

Code Style

Go Version: 1.24+
Linter: golangci-lint with comprehensive rules (see .golangci.yml)
Testing: Use testify/assert for assertions
Error Handling: Check all errors (errcheck enabled)
Type Assertions: Must check type assertions (check-type-assertions enabled)
Exhaustiveness: Switch statements and map iterations must be exhaustive

Read the full file on GitHub · 198 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.

1mo ago First seen · 198 lines · 1,468 tokens per session scan A 4df3a9f8b1cd

Subscribe to this mod's changes

apigen AGENTS.md is an instructions file published in the GitHub repository gemyago/apigen (6 stars, last pushed 11mo ago), licensed Apache-2.0. It adds 1,468 tokens to every session, about $0.0059 per session on Opus 5.5. 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 2026-10-02.

Backend and APIs Code Generation Go Languages api go http openapi

apigen AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
apigen AGENTS.mdgemyago/apigen	Instructions file	6	11mo ago	Apache-2.0	A	1,468	Codex, OpenCode
vscode buildNext.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	9,719	GitHub Copilot
next.js AGENTS.mdvercel/next.js	Instructions file	143k	today	MIT	A	7,461	Codex, OpenCode
langchain AGENTS.mdlangchain-ai/langchain	Instructions file	149k	yesterday	MIT	A	4,680	Codex, OpenCode
vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

apigen: Instructions file for Codex