What is gnucobol AGENTS.md?

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

Use it when changing Dockerfiles, COBOL smoke tests, compiler versions, runtime images, or the project’s update scripts.

It gives coding agents the project’s layout, build commands, naming rules, and testing expectations so they can work consistently.

How brazilofmux/gnucobol configures Codex and OpenCode

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/brazilofmux/gnucobol/agents-md/github.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/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/brazilofmux/gnucobol/agents-md"><img src="https://agentmods.dev/badge/instructions/brazilofmux/gnucobol/agents-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 619 This file is loaded in full into every session.

When invoked 619 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	$0.00619	$0.00619
Opus 5.5	$0.00248	$0.00248
Sonnet 5.5	$0.00124	$0.00124
Haiku 4.5	$0.00062	$0.00062

Measured 29d ago against content hash bb236bce1685, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, 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 29d 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.

3.1/, 3.2/, 3.3/, 4.0/: one container stack per GnuCOBOL line, each with builder/, runtime/, hello/. The directory name is the line's tag; its pinned tag is in runtime/Dockerfile.
*/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: builds any line locally, the way the fleet job in ~/builder does. update.sh is superseded (see CLAUDE.md).

Build, Test, and Development Commands

./daily.sh 4.0: build gnucobol:4.0-builder, -runtime and -hello (and the pinned 4.0-r5725-*); ./daily.sh alone builds every line.
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 line with ./daily.sh <line> after changing its Dockerfiles.
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.

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.

29d ago Changed · +35 tokens per session bb236bce1685
2mo 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 29d ago), licensed MIT. It adds 619 tokens to every session, about $0.0025 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 2026-08-31.

Languages

gnucobol AGENTS.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
gnucobol AGENTS.mdbrazilofmux/gnucobol	Instructions file	5	29d ago	MIT	A	619	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	yesterday	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

gnucobol: Instructions file for Codex