just ยท diff
git:20260311.2728069 to git:20260619.a0fe9cb
1 added, 0 removed. Audit A to A.
---
name: just
description: >-
Prefer the nearest relevant `justfile` as the default command surface for
build, test, lint, format, run, deploy, and repo automation workflows. Use
when a repo or subproject has a `justfile`, or when the user mentions `just`,
`justfile`, recipes, or Makefile-to-just migration.
---
# Just
Use this skill when a repo may expose commands through `justfile`.
Treat `just` as the canonical task interface when it exists. Prefer existing
recipes over reconstructing the underlying `go`, `npm`, `cargo`, `docker`,
`make`, or shell commands by hand.
## When To Use This Skill
Use it when:
- the repo or a nearby subproject has a `justfile`
- the user asks how to build, test, lint, run, deploy, or inspect commands
- the user mentions `just`, `justfile`, recipes, or recipe arguments
- the repo has both `Makefile` and `justfile` and you need to understand which
command surface is intended
- the user wants to migrate from `make` to `just`
## Default Workflow
1. Find the nearest relevant `justfile`. Do not assume repo root.
2. Run `just --list` in that directory to discover the supported UX.
3. If a recipe is unclear, inspect it with `just --show <recipe>`.
4. Use the recipe directly unless the user explicitly wants the raw command.
5. Fall back to ad hoc commands only when no suitable recipe exists.
Common recipe names to check first: `setup`, `install`, `build`, `test`, `lint`,
`fmt`, `dev`, `run`, `preview`, `deploy`.
## Agent Guardrails
- Prefer the nearest task-specific `justfile` over a broader root-level one.
- If both `Makefile` and `justfile` exist, inspect both before suggesting
migration or replacement.
- Do not bypass an existing recipe unless it is missing, clearly wrong for the
task, or the user asks for the underlying command.
- Do not assume `.env` exists, and do not print secrets just because a
`justfile` uses `dotenv-load` or exported variables.
- Treat destructive or confirmation-gated recipes cautiously.
+ - Test-like shebang recipes (`test`, `test-*`, etc.) should use `#!/usr/bin/env bash` and `set -euo pipefail` so failures propagate instead of being masked by later commands.
## Common Failure Modes
### Wrong Working Directory
Nested `justfile`s are common. If commands look wrong, verify you are running in
the correct subproject. When needed, invoke a specific file directly with
`just --justfile path/to/justfile <recipe>` instead of guessing.
### Sparse Or Misleading `--list` Output
Some repos split recipes across imported files or modules. If `just --list`
looks too small, inspect the `justfile` for `import` or `mod` statements before
assuming recipes are missing.
### Hidden Helper Recipes
`[private]` recipes do not appear in `just --list` or `just --summary`, so they
do not pollute help output. They are still valid recipe entry points and can be
invoked directly with `just <private-recipe>` when an internal workflow, CI job,
or explicit user request needs them. Check `just --show <recipe>`, use
`just --dry-run <recipe>`, or inspect the file if a public recipe depends on
helpers you cannot see in the listing.
### Env Or Shell Drift
Behavior can change based on settings such as:
- `set dotenv-load`
- `set export`
- `set shell := [...]`
- `set positional-arguments`
If a recipe works differently in CI, in a subdirectory, or in the terminal,
check these settings before changing the command.
### Confirmation Gates
Recipes marked with `[confirm]` may block or fail in non-interactive contexts.
Treat them as intentional safety rails, especially for `destroy`, `clean`, or
production deploy flows.
## Quick Command Reference
- `just --list` list public recipes with descriptions
- `just --show <recipe>` show the resolved recipe body
- `just --summary` list recipe names only
- `just --dry-run <recipe>` print commands without executing them, including
private recipes
- `just --dump` print the full justfile
- `just --evaluate` inspect variable evaluation
- `just <recipe> [args...]` run a recipe
- `just --justfile path/to/justfile <recipe>` target a specific justfile
## Notes
- Comments above recipes become descriptions in `just --list`.
- Each recipe line runs in a separate shell unless the recipe is a shebang
script.
- Large repos may use `just` as a command hub over other toolchains rather than
exposing the toolchain directly.
## References
- [references/make-migration.md](references/make-migration.md)
- [references/justfile-patterns.md](references/justfile-patterns.md)