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cli-just — Claude Code skill: what it does, how to install

Configures task automation with just: creates justfiles, writes recipes, and checks syntax against the installed CLI version.

Install into Claude Code · Skills CLI (Vercel) All methods and platforms ↓
npx skills add PaulRBerg/agent-skills --skill cli-just -a claude-code
Open on GitHub

What cli-just does

This skill guides coding agents through creating and editing justfile configurations. Before making any edits, the agent runs just --version, lists existing recipes with just --list, and inspects module trees. The installed binary sets the rules. The skill avoids enabling unstable flags unless the target environment supports them and the user specifically requests them.

When building a new file, recipes follow a set layout: dependencies and constants come first, followed by public targets, checks, and private helpers. Multi-item strings are kept one per line inside parenthesized concatenations rather than wrapped strings. Triple-quoted blocks are saved strictly for values where newlines carry meaning.

Existing repository formatting takes priority over standard tools. The agent avoids rewriting files with just --fmt, reserving just --fmt --check for repositories that enforce it. Validation always relies on just --list or just --summary, paired with a dry run before running any recipe that alters state.

What it helps with

  • write new build and test recipes in a justfile
  • configure modules, settings, and dotenv files for just
  • validate recipe syntax with just --list or just --summary
  • split targets into public commands and private helper recipes

Example prompts for the agent

  • Create a justfile for building the Go service and running linters
  • Add a recipe to the justfile that runs integration tests with dry-run support
  • Clean up recipes in our justfile and enable default-list

How to install cli-just

1Skills CLI (Vercel)

npx skills add PaulRBerg/agent-skills --skill cli-just -a claude-code

2Manually: put the files in place

~/.claude/skills/cli-just/SKILL.md

Copy the whole skill folder; for one project use .claude/skills/cli-just/

Step by step, with commands for each platform: How to install skills in Claude Code: five ways

Questions about cli-just

How do I install cli-just in Claude Code?

Run npx skills add PaulRBerg/agent-skills --skill cli-just -a claude-code in your terminal.

What does cli-just do?

It guides the agent in writing readable, maintainable justfile recipes that match the repository style and the installed just version.

Does the skill automatically reformat justfiles?

No. It preserves existing formatting instead of running just --fmt, and only uses just --fmt --check if the repository explicitly requires the built-in formatter.

Source text

SKILL.md · MIT
---
name: cli-just
user-invocable: false
description:
  "Use for just/justfile task automation: create justfiles, write recipes, configure settings, add modules/attributes,
  or set up command-runner workflows."
---

# Just Command Runner

Create readable task automation that matches the repository's installed Just version and existing justfile conventions.

## Defaults

- Inspect `just --version`, the existing justfile/module tree, and `just --list` before editing. Installed capabilities
  and existing syntax are authoritative over this skill's examples.
- Preserve bespoke formatting. Do not rewrite a justfile with `just --fmt`. Use `just --fmt --check` only when the
  repository explicitly treats the built-in formatter as authoritative. `just --dump` is inspection output, not a
  formatting source.
- Define multi-item string sequences one item per line with a parenthesized concatenation. Keep a trailing separator in
  every non-final item. Do not combine them into one long string. Triple-quoted strings are for values whose newlines
  are semantic, not visual wrapping. For example:

  ```just
  check-steps := (
    "event-class-coverage " +
    "orphan-disposal " +
    "price-coverage"
  )
  ```

- When creating a new standalone justfile, use the user's section-banner style. Existing repository organization
  overrides that style.

## Workflow

1. Determine the requested recipe behavior, inputs, outputs, cwd, shell, environment, dependencies, and success
   condition.

2. Use the installed manual (`just --help`, `just --man`, or <https://just.systems/man/en/>) for version-sensitive
   syntax. Read only the task-specific reference:

   | Task                                                                    | Reference                      |
   | ----------------------------------------------------------------------- | ------------------------------ |
   | Recipes, parameters, dependencies, cache, executable checks, echo rules | `references/recipes.md`        |
   | Settings, dotenv, lists, modules                                        | `references/settings.md`       |
   | Expressions, functions, constants                                       | `references/syntax.md`         |
   | Shell or script recipes, macOS Bash constraints                         | `references/inline-scripts.md` |
   | Check/write, status, aliases, organization                              | `references/patterns.md`       |

3. Make the smallest recipe or setting change. Do not enable unstable features unless the requested design needs them
   and the installed version supports them.

4. Validate parsing with `just --list` or `just --summary`. Then execute the narrowest safe recipe path. For
   state-changing recipes, use an existing dry-run/check mode or inspect the expanded command first.

## Opinionated Organization

For a new standalone file, prefer dependency declarations, constants, public recipes, checks, then private helpers. Use
`set default-list := true` when no single default action makes sense and the installed version supports it. Example
starting points are in `examples/standalone.just` and `examples/devkit.just`. Load one only when creating that shape.

Completion requires a parsable justfile, the requested recipe behavior, and execution or dry-run evidence appropriate to
its side effects. Finish with `### ✅ Just workflow ready`, a compact recipe/alias/purpose table when several entries
changed, and `### 🧪 Verification` with exact commands and outcomes. Keep confirmation prompts, recipe data output,
compiler output, and `just --list` output undecorated. Preserve the repository's own banner vocabulary.

© PaulRBerg · MIT · PaulRBerg/agent-skills

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