devenv-init

name	devenv-init
description	Use when initializing a new project with devenv, direnv, and jj version control. Triggers on: setting up dev environment, configuring nix shell, project bootstrap.

Initialize Devenv + Direnv + JJ

Overview

Bootstrap a development environment with jj (git-backed), devenv (nix-based tools), and direnv (auto-activation). Idempotent - safe to run multiple times to update configuration.

Quick Start

bash .claude/skills/devenv-init/setup-devenv.sh           # Full setup
bash .claude/skills/devenv-init/setup-devenv.sh --force   # Regenerate devenv.nix
bash .claude/skills/devenv-init/setup-devenv.sh --analyze # Analyze only

What It Does

1. Ensures jj repo - Initializes if git exists but jj doesn't
2. Warns on missing remotes - Continues anyway
3. Analyzes repo - Detects language, tools, scripts, tasks
4. Creates/updates .envrc - Works with OR without devenv
5. Generates devenv.nix - With detected configuration
6. Creates devenv.yaml - Nixpkgs input

Auto-Detection

Detected	Source	Generated Config
Rust	Cargo.toml	languages.rust, cargo-watch, rustfmt/clippy hooks
Python	pyproject.toml	languages.python, ruff, uv, pytest
Node	package.json	languages.javascript, pnpm/yarn, scripts from package.json
Go	go.mod	languages.go, golangci-lint, gofmt hook
Tools	Makefile, justfile	packages (gnumake, just)

Idempotency

File	Behavior on Re-run
.envrc	Updates if managed, backs up if not
devenv.nix	Skips unless --force, backs up if unmanaged
devenv.yaml	Skips if exists
.jj	Initializes only if missing

Files managed by this skill contain a marker comment. Unmanaged files are backed up before overwriting.

Options

--force, -f    Regenerate devenv.nix even if already managed
--analyze, -a  Only analyze repo, show recommendations, don't write
--help, -h     Show help

Generated Sections

Section	Auto-populated From
packages	Detected tools (cargo-watch, ruff, pnpm, etc)
scripts	Common dev commands (check, lint, test, dev)
tasks	Build/test commands for devenv tasks run
processes	Dev servers from package.json scripts
pre-commit.hooks	Language-appropriate formatters/linters

.envrc Behavior

The generated .envrc gracefully handles:

1. devenv installed: Full devenv shell activation
2. nix only: Falls back to use_nix
3. Neither: Succeeds silently (no-op)

Querying Devenv Options

Use devenv-query.sh to explore available options without loading full docs:

# List all available languages
bash .claude/skills/devenv-init/devenv-query.sh langs

# List all available services
bash .claude/skills/devenv-init/devenv-query.sh services

# Search options for a specific feature
bash .claude/skills/devenv-init/devenv-query.sh options languages.rust
bash .claude/skills/devenv-init/devenv-query.sh options services.postgres

# Search nixpkgs for packages
bash .claude/skills/devenv-init/devenv-query.sh packages ripgrep

# Evaluate current devenv.nix config (returns JSON)
bash .claude/skills/devenv-init/devenv-query.sh eval languages.rust.enable

Results are cached for 24h in ~/.cache/devenv-init/.

Troubleshooting

Issue	Fix
"No git or jj repository"	Run git init first
"Not git-backed"	Run jj git init --colocate
Want to regenerate	Run with --force
Wrong detection	Edit devenv.nix manually, it won't be overwritten
Need option details	Run devenv-query.sh options <path>