gnucobol: Instructions file for Codex

AGENTS.md

gnucobol AGENTS.md is an instructions file for Codex, OpenCode from brazilofmux/gnucobol. It costs 584 tokens per session, scanned A, original, MIT.

A repository instruction file for the GnuCOBOL project, which packages several versions of the COBOL programming language compiler into container images.

In plain words
What is it for?
Use it when changing Dockerfiles, COBOL smoke tests, compiler versions, runtime images, or the project’s update scripts.
Why use it?
It gives coding agents the project’s layout, build commands, naming rules, and testing expectations so they can work consistently.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md.

This is brazilofmux/gnucobol's own configuration. It tells Codex and OpenCode how to work on gnucobol itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything gnucobol configures →

Reuse

Borrowing it

Nothing to install: this file belongs to brazilofmux/gnucobol. 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/brazilofmux/gnucobol/master/AGENTS.md
Clone the repo
git clone --depth 1 https://github.com/brazilofmux/gnucobol

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.

agentmods badge for gnucobol AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/brazilofmux/gnucobol/agents-md.svg)](https://agentmods.dev/instructions/brazilofmux/gnucobol/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/brazilofmux/gnucobol/agents-md"><img src="https://agentmods.dev/badge/instructions/brazilofmux/gnucobol/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 584 This file is loaded in full into every session.
When invoked 584 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00584 $0.00584
Opus 5 $0.00292 $0.00292
Sonnet 5 $0.00117 $0.00117
Haiku 4.5 $0.00058 $0.00058

Measured 6d ago against content hash 605a5fa4770c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

gnucobol 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 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.

AGENTS.md · 40 lines

How it starts

The opening of the file, as written. The whole thing — 40 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Repository Guidelines

Project Structure & Module Organization

This repository wraps multiple GnuCOBOL releases as container builds.

  • 3.0/, 3.1/, 3.2/, 4.0/: versioned container stacks with builder/, runtime/, hello/, and a local daily.sh.
  • */builder/Dockerfile: builds the compiler image from the packaged source tarball.
  • */runtime/Dockerfile: trims the runtime dependencies for compiled COBOL programs.
  • */hello/test.cob: minimal smoke-test program used by the hello image.
  • daily.sh and update.sh: reference scripts that document the release/update flow more than day-to-day development.

Build, Test, and Development Commands

  • cd 4.0 && ./daily.sh: build gnucobol:4.0-builder, gnucobol:4.0-runtime, and gnucobol:4.0-hello with podman.
  • cd 4.0/builder && podman build -t gnucobol:4.0-builder .: rebuild one image while iterating on a Dockerfile.
  • cd 4.0/hello && podman build -t gnucobol:4.0-hello .: rebuild the smoke-test image after editing test.cob.
  • cd 4.0/runtime && podman build -t gnucobol:4.0-runtime .: validate runtime-layer changes in isolation.

Coding Style & Naming Conventions

Follow the style already in the tree.

  • Use 4-space indentation in shell scripts and keep loops/simple command sequences compact.
  • Preserve the existing split between builder, runtime, and hello under each version directory.
  • Keep COBOL examples minimal and readable; the current test.cob files use classic uppercase COBOL formatting.
  • Prefer small, targeted edits and keep version-specific changes isolated to the matching directory.

Testing Guidelines

There is no separate test framework in this repository; validation is build-based.

  • Rebuild the affected container stack with ./daily.sh after changing Dockerfiles or version scripts.
  • Rebuild the specific hello image if you change a sample program or compiler flags.
  • Treat a clean podman build and a working hello image as the minimum acceptance bar.

Commit & Pull Request Guidelines

Recent history favors short, imperative commit subjects such as Fix build again and Add update.sh.

Read the full file on GitHub · 40 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. 6d ago First seen · 40 lines · 584 tokens per session scan A 605a5fa4770c

Subscribe to this mod's changes

gnucobol AGENTS.md is an instructions file published in the GitHub repository brazilofmux/gnucobol (5 stars, last pushed 22d ago), licensed MIT. It adds 584 tokens to every session, about $0.0029 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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