prereq-checker

name	prereq-checker
description	Check tool availability for the current session. Auto-detects required tools from project context or accepts an explicit list. Groups results by status and suggests install commands for missing tools.

Prerequisite Checker

Check whether required CLI tools are available in the current environment.

Step 1: Determine Required Tools

If the user provided specific tool names as arguments, check those.

Otherwise, auto-detect from project context by checking for these files:

File	Tools to check
package.json	node, npm (or yarn, pnpm, bun if referenced in packageManager field)
go.mod	go
Cargo.toml	cargo, rustc
pyproject.toml / requirements.txt	python3, pip (or uv, poetry if referenced)
Gemfile	ruby, bundle
mix.exs	elixir, mix
Dockerfile / docker-compose.yml	docker, docker-compose
.github/ directory	gh
Makefile / justfile	make / just
Taskfile.yml	task

Always check these baseline tools regardless: git, gh.

Step 2: Check Availability

For each tool, run:

command -v <tool> 2>/dev/null && <tool> --version 2>/dev/null | head -1

If --version fails, try -v, -V, or version subcommand. Record:

• Tool name
• Whether it exists (command -v exit code)
• Version string (if available)

Step 3: Detect Environment

Check for devcontainer / remote environment:

# Devcontainer indicators
[ -f /.dockerenv ] && echo "Docker container detected"
[ -n "$REMOTE_CONTAINERS" ] && echo "VS Code devcontainer detected"
[ -d "/workspaces" ] && echo "Codespaces/devcontainer workspace detected"
[ -n "$CODESPACES" ] && echo "GitHub Codespaces detected"

Store the environment type — it affects install command suggestions.

Step 4: Report Results

Group tools into three categories and present:

Installed

List each tool with its version.

Missing (Optional)

Tools that would be useful but aren't strictly required. No action needed.

Missing (Required)

Tools that the project needs to build/run/test. Suggest install commands based on the detected environment:

Environment	Package manager
Debian/Ubuntu container	apt-get install -y <package>
Alpine container	apk add <package>
macOS	brew install <package>
Generic Linux	curl/wget install commands or distro-agnostic methods

Step 5: Summary

Print a one-line summary:

Prerequisites: N/M installed (K required tools missing)

If all required tools are present: "All prerequisites satisfied."