atmos CLAUDE.md

Project instructions for Atmos, a Go command-line tool for managing cloud infrastructure. They cover the project structure, mandatory Git worktrees, concurrent work, and maintenance practices.

In plain words
What is it for?
Use them when working on Atmos code, especially while navigating worktrees, handling parallel sessions, or maintaining pull requests.
Why use it?
They prevent agents from inspecting the wrong worktree or making changes without following the repository's development rules.

Instructions file

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 instructions/cloudposse/atmos/claude-md
Clone the repo
git clone --depth 1 https://github.com/cloudposse/atmos
Per session 6,115 This file is loaded in full into every session.
When invoked 6,115 The same file — it is already loaded in full.
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 $0.06115 $0.06115
Opus 5 $0.03057 $0.03057
Sonnet 5 $0.01223 $0.01223
Haiku 4.5 $0.00611 $0.00611

Measured 3d ago against content hash 54f945dcd765, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

atmos CLAUDE.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 3d 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.

CLAUDE.md · 453 lines

How it starts

The opening of the file, as written. The whole thing — 453 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

Guidance for Claude Code when working with this repository.

Project Overview

Atmos: Go CLI for cloud infrastructure orchestration via Terraform/Helmfile/Packer with stack-based config, templating, policy validation, vendoring, and terminal UI.

Git Worktrees (MANDATORY)

This repository uses git worktrees for parallel development. When working in a worktree:

  • ALWAYS stay within the current working directory - Never escape to parent directories
  • Use relative paths or paths under the current working directory - Do not hardcode /Users/*/atmos/ paths
  • The worktree IS the repository - All files, including pkg/, cmd/, internal/, exist within the worktree
  • Never assume the parent directory is the repo - Worktrees like .conductor/branch-name/ are complete, independent working copies

Why this matters: Searching outside the worktree will find stale code from the main branch instead of the current branch's code. This leads to incorrect analysis and recommendations.

For Task agents: When searching for files, always use the current working directory (.) or relative paths. Never construct absolute paths that might escape the worktree.

Concurrent Sessions (MANDATORY)

Multiple Claude sessions may be working on the same branch or worktree simultaneously. To avoid destroying other sessions' work:

  • NEVER delete, reset, or discard files you didn't create - Other sessions may have created them
  • NEVER run git reset, git checkout --, or git clean without explicit user approval
  • NEVER run go clean. In particular, go clean -cache deletes the shared Go build cache and breaks concurrent builds; it is not an approved troubleshooting step.
  • ALWAYS ask the user before removing untracked files - They may be work-in-progress from another session
  • When you see unfamiliar files, assume another session created them - ask the user what to do
  • If pre-commit hooks fail due to files you didn't touch, ask the user how to proceed rather than trying to fix or remove them

Read the full file on GitHub · 453 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. 3d ago First seen · 453 lines · 6,115 tokens per session scan A 54f945dcd765

Subscribe to this mod's changes

atmos CLAUDE.md is an instructions file published in the GitHub repository cloudposse/atmos (1,367 stars, last pushed yesterday), licensed Apache-2.0. It adds 6,115 tokens to every session, about $0.0306 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 2026-08-30.