setup-devenv

setup-devenv is a skill for Claude Code, Codex from urmzd/dotfiles. It costs 102 tokens per session (856 once invoked), scanned A, original, Apache-2.0.

A guide for setting up project-specific programming runtimes and environment variables, using tools such as fnm for Node.js, uv for Python, and rustup for Rust.

In plain words
What is it for?
Use it when bootstrapping a development environment, choosing a runtime version manager, or writing a direnv .envrc file.
Why use it?
It makes local development use the intended language versions and environment settings when entering a project directory.

Skill for Claude CodeCodex

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 skills/urmzd/dotfiles/setup-devenv
Any agent
npx skills add urmzd/dotfiles --skill setup-devenv
Clone the repo
git clone --depth 1 https://github.com/urmzd/dotfiles

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 setup-devenv

README.md
[![agentmods](https://agentmods.dev/badge/skills/urmzd/dotfiles/setup-devenv.svg)](https://agentmods.dev/skills/urmzd/dotfiles/setup-devenv)
Your own site
<a href="https://agentmods.dev/skills/urmzd/dotfiles/setup-devenv"><img src="https://agentmods.dev/badge/skills/urmzd/dotfiles/setup-devenv.svg" alt="Measured on agentmods" height="20"></a>
Per session 102 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 856 The whole file, excluding the scripts and references it only reads on demand.
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 $0.00102 $0.00856
Opus 5 $0.00051 $0.00428
Sonnet 5 $0.00020 $0.00171
Haiku 4.5 $0.00010 $0.00086

Measured 3d ago against content hash 5eeea1d035a8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

setup-devenv 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.

dot_agents/skills/setup-devenv/SKILL.md · 68 lines

How it starts

The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Per-Language Dev Environments

Philosophy

System-installed CLIs (git, gh, fzf, jq, kubectl, terraform, ...) come from Homebrew on macOS or apt/dnf/pacman on Linux. Per-language runtime versions come from the best-in-class tool for that language. No polyglot abstraction layer.

Runtime version managers

Language Tool Project pin Notes
Node fnm .nvmrc eval "$(fnm env --use-on-cd)" in shell rc auto-switches
Python uv .python-version + pyproject.toml uv venv + uv sync
Rust rustup rust-toolchain.toml Auto-installs the pinned channel
Go system go go.mod go directive One toolchain per machine usually fine
Lua system lua n/a Pin via Brewfile/apt

.envrc patterns (vanilla direnv, no nix-direnv)

The standard direnv idioms cover most needs:

# Python: auto-create + activate .venv on cd
layout python

# Node with fnm: load .nvmrc-pinned version
use fnm

# Add project-local bin/ to PATH
PATH_add bin

# Load KEY=VALUE pairs from .env
dotenv

# Inherit ~/.envrc (which sources ~/.envrc.local for personal defaults)
source_up

For a working template, see the chezmoi-tracked ~/.local/share/chezmoi/dot_envrc.project.example (renders to ~/.envrc.project.example); see setup-devenv-with-chezmoi for the chezmoi plumbing. If you are not on chezmoi, copy the idioms above directly into your project .envrc.

When to add an upstream installer

Adopt a one-shot installer script (e.g. a chezmoi run_onchange_after_install-<tool>.sh.tmpl, a Brewfile entry, or a Nix derivation) with a pinned version when:

  • The tool ships security/auth fixes faster than distro repos can package them (gcloud, aws-cli)
  • The vendor distributes only via their own installer with no version-arg support (Snowflake Cortex)
  • Reproducibility across machines matters more than the convenience of brew upgrade

Read the full file on GitHub · 68 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 · 68 lines · 102 tokens per session scan A 5eeea1d035a8

Subscribe to this mod's changes

setup-devenv is a skill published in the GitHub repository urmzd/dotfiles (3 stars, last pushed 21d ago), licensed Apache-2.0. It adds 102 tokens to every session and 856 once invoked, about $0.0005 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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