---

name: just-cli description: This skill should be used when the user asks to "create a justfile", "write just recipes", "configure just settings", "add just modules", "use just attributes", "set up task automation", mentions justfile, just command runner, or task automation with just.

Just Command Runner

Overview

Expert guidance for Just, a command runner with syntax inspired by make. Use this skill for creating justfiles, writing recipes, configuring settings, and implementing task automation workflows.

Justfile Discovery Protocol

When a justfile exists in a project, agents should prefer just recipes over raw commands.

Discovery Steps

1. Check for justfile or Justfile in project root
2. Run just --list to discover available recipes
3. Map common operations to recipes:

Common Recipe Naming Conventions

• test / t - Run test suite
• build / b - Build project
• lint - Run linter
• fmt - Format code
• check - Type checking / static analysis
• coverage - Generate coverage report
• audit - Security audit
• dev / serve - Start development server
• clean - Remove build artifacts
• full-check / fc - Run all checks

Key capabilities:

• Create and organize justfiles with proper structure
• Write recipes with attributes, dependencies, and parameters
• Configure settings for shell, modules, and imports
• Use built-in constants for terminal formatting
• Implement check/write patterns for code quality tools

Quick Reference

Essential Settings

Copyset allow-duplicate-recipes       # Allow recipes to override imported ones
set allow-duplicate-variables     # Allow variables to override imported ones
set shell := ["bash", "-euo", "pipefail", "-c"]  # Strict bash with error handling
set unstable                      # Enable unstable features (modules, script attribute)

Environment Variables: Use mise for environment variable management instead of Just's dotenv settings. mise provides project-scoped env vars via .mise.toml with better tooling integration.

Common Attributes

Multiple attributes can be combined:

Copy[no-cd, private]
[group("checks")]
recipe:
    echo "hello"

Built-in Constants

Terminal formatting constants are globally available (no definition needed):

Usage:

Copy@status:
    echo -e '{{ GREEN }}Success!{{ NORMAL }}'
    echo -e '{{ BOLD + CYAN }}Building...{{ NORMAL }}'

Key Functions

Copy# Require executable exists (fails recipe if not found)
jq := require("jq")

# Get environment variable with default
log_level := env("LOG_LEVEL", "info")

# Get justfile directory path
root := justfile_dir()

Recipe Patterns

Status Reporter Pattern

Display formatted status during multi-step workflows:

Copy@_run-with-status recipe *args:
    echo ""
    echo -e '{{ CYAN }}→ Running {{ recipe }}...{{ NORMAL }}'
    just {{ recipe }} {{ args }}
    echo -e '{{ GREEN }}✓ {{ recipe }} completed{{ NORMAL }}'
alias rws := _run-with-status

Check/Write Pattern

Pair check (verify) and write (fix) recipes for code quality tools:

Copy[group("checks")]
@biome-check +globs=".":
    na biome check {{ globs }}
alias bc := biome-check

[group("checks")]
@biome-write +globs=".":
    na biome check --write {{ globs }}
alias bw := biome-write

Full Check/Write Pattern

Aggregate all checks with status reporting:

Copy[group("checks")]
@full-check:
    just _run-with-status biome-check
    just _run-with-status prettier-check
    just _run-with-status tsc-check
    echo ""
    echo -e '{{ GREEN }}All code checks passed!{{ NORMAL }}'
alias fc := full-check

[group("checks")]
@full-write:
    just _run-with-status biome-write
    just _run-with-status prettier-write
    echo ""
    echo -e '{{ GREEN }}All code fixes applied!{{ NORMAL }}'
alias fw := full-write

Standard Alias Conventions

Modules & Imports

Import Pattern

Include recipes from another file:

Copyimport "./just/settings.just"
import "./just/base.just"
import? "./local.just"    # Optional (no error if missing)

Module Pattern

Load submodule (requires set unstable):

Copymod foo                   # Loads foo.just or foo/justfile
mod bar "path/to/bar"     # Custom path
mod? optional             # Optional module

# Call module recipes
just foo::build

Devkit Import Pattern

For projects using @sablier/devkit:

Copyimport "./node_modules/@sablier/devkit/just/base.just"
import "./node_modules/@sablier/devkit/just/npm.just"

Section Organization

Standard section header format:

Copy# ---------------------------------------------------------------------------- #
#                                 DEPENDENCIES                                 #
# ---------------------------------------------------------------------------- #

Common sections (in order):

1. DEPENDENCIES - Required tools with URLs
2. CONSTANTS - Glob patterns, environment vars
3. RECIPES / COMMANDS - Main entry points
4. CHECKS - Code quality recipes
5. UTILITIES / INTERNAL HELPERS - Private helpers

Default Recipe

Always define a default recipe:

Copy# Show available commands
default:
    @just --list

Dependencies Declaration

Document required tools at the top:

Copy# ---------------------------------------------------------------------------- #
#                                 DEPENDENCIES                                 #
# ---------------------------------------------------------------------------- #

# Bun: https://bun.sh
bun := require("bun")

# Ni: https://github.com/antfu-collective/ni
na := require("na")
ni := require("ni")
nlx := require("nlx")

Context7 Fallback

For Just features not covered in this skill (new attributes, advanced functions, edge cases), fetch the latest documentation:

CopyUse context7 MCP with library ID `/websites/just_systems-man` to get up-to-date Just documentation.

Example topics to search:

• modules import mod - Module system details
• settings - All available settings
• attributes - Recipe attributes
• functions - Built-in functions
• script recipes - Script block syntax

Additional Resources

Reference Files

For detailed patterns and comprehensive coverage, consult:

• reference.md - Complete settings, modules, attributes, functions reference
• patterns.md - Established conventions, section organization, helper patterns

External Documentation

• Official Manual: https://just.systems/man/en/
• GitHub Repository: https://github.com/casey/just
• Context7 Library ID: /websites/just_systems-man

Important Limitations

Just does not support flags. Recipe parameters are positional only:

Copy# WRONG: Flags don't work
build --release:  # This won't work!

# CORRECT: Use positional parameters
build mode="debug":
    cargo build {{ if mode == "release" { "--release" } else { "" } }}

# Usage: just build release

For complex flag-like behavior, use environment variables or positional parameters with defaults.

Tips

1. Use @ prefix to suppress command echo: @echo "quiet"
2. Use + for variadic parameters: test +args
3. Use * for optional variadic: build *flags
4. Quote glob patterns in variables: GLOBS := "\"**/*.json\""
5. Use [no-cd] in monorepos to stay in current directory
6. Private recipes start with _ or use [private]
7. Always define aliases after recipe names for discoverability