prelude-just

Prelude + Just

The Justfile stays the canonical owner of task semantics; Prelude imports it at runtime — recipes are never copied into prelude.commands. Treat the user's request as the specification, never as shell text to interpolate. Bind every recipe to the project's real canonical command — the invocation the tool owner already uses (bun run test, go test ./..., nix flake check) — and confirm it actually exists in the repo before writing it; never invent placeholder scripts.

Enable the import (once)

In the flake-parts module (sidecar prelude.nix or inline configuration):

prelude.menu.enable = true;
prelude.menu.just.enable = true;
# prelude.menu.just.justfile = ./just/Justfile;  # pin; null = just's own discovery
# prelude.menu.just.group = "tasks";             # menu group for flat recipes

With config.packages.prelude-shell in the consumer devshell, enabling both options provides x and just. The Justfile import flag alone does not enable the menu. See /prelude-install if shell integration is missing.

Attribute support is version-gated in just ([metadata] 1.42+, [arg(long/short)] 1.46+, [arg(pattern)] 1.45+, [arg(min/max)] 1.56+) and the import itself only maps fields the consumer's locked Prelude revision knows — check just --version and confirm against the locked prelude input before relying on an attribute. An existing prelude.commands.<name> entry always wins over a same-named recipe.

Author recipes the import understands

The menu reads just --dump --dump-format json; only these fields surface:

• # doc comment → menu description
• [group('ci')] → menu group; the key stays flat (x check)
• alias ship := deploy → its own entry, inheriting target's doc and group
• mod ops 'ops.just' → ONE x ops row; Enter (or bare x ops) opens a subcommand

picker over the module's recipes, while recipes dispatch publicly via parent routing (x ops migrate, or x ops <recipe> [args…]). The recipe executes internally via its canonical command (just ops::migrate). Imported module recipes cannot be selected through double-colon keys (x ops::migrate). A module de-clutters the menu instead of adding one row per recipe. Modules do not inherit the parent Justfile's set settings or recipes; module recipes need their own private helpers (dependencies cannot cross module boundaries).

• [group('ops')] on a module recipe → the recipe escapes the submenu and stays top-level

in that group in the menu, while remaining callable via parent routing (x ops migrate)

• [private] or leading _ → omitted from the menu (recipes and aliases)
• [metadata('just test --fix')] → one worked Example row in the details pane
• [arg('package', long)] → --package option in argument entry
• [arg('dry', long, flag)] → toggleable flag in argument entry
• [arg('kind', pattern='staging|production')] → pickable options (plain pipe

alternation; a regex like [a-z-]+ is enforced but renders no options)

• default on the recipe line (package="./...") → optional arg pre-filled

Canonical shape — adapt these commands to the project's actual tooling:

# run the unit test suite
[group('ci')]
test:
    bun run test

# run go tests for one package
# (add [group('go')] if a go group is wanted)
[arg('package', help='import path, or ./... for all')]
test-go $package="./...":
    go test "$package"

# E2E suites grouped behind one menu row: `just e2e <suite>`
mod e2e 'e2e.just'

with e2e.just carrying its own private helpers:

[private]
guard:
    @test -n "${IN_NIX_SHELL:-}"

# run the desktop e2e suite
[metadata('just e2e desktop main')]
[arg('revision', help='branch, commit, PR number or URL')]
desktop $revision="main": guard
    bun run desktop-test smoke "$revision"

$package exports the parameter into the recipe environment; "$package" preserves it as one shell argument. Raw {{…}} interpolation inserts text into shell source; merely surrounding it with quotes does not make arbitrary values safe. Prefer exported parameters with quoted shell expansion.

Rules:

• Prefer [group] over renaming — the public key stays x test.
• Argument attributes can change invocation semantics and require a newer

Just version; long/short options in particular change positional usage. Preserve existing invocation forms unless the task calls for changing them. Private/group/metadata attributes affect visibility or presentation and also need support from the installed Just version.

• A parameter with no default is required; argument entry rejects blank submit

until it is filled.

• Scope edits to the request; never rename recipes — that changes public keys.

Moving recipes into a module changes their invocation path (e.g. x coder-e2e → x e2e coder, internal just e2e::coder); do it only when the user asks for that reorganization, and update any docs that show the old invocation.

Dispatch contract

x <recipe> [args…] currently joins extra arguments with spaces and executes the assembled command through sh -c. Original argument boundaries are lost: quotes used by the calling shell do not protect multiword values, and embedded metacharacters can become shell syntax. Use direct just <recipe> "$value" for multiword or untrusted values, with safe parameter handling in the recipe itself. Do not describe x forwarding as argv-preserving.

Bare x <recipe> opens interactive argument entry when parameters exist. Bare x <module> opens the module's subcommand picker. Module recipes dispatch as x <module> <recipe> [args…] (or nested x <parent> [submodule…] <recipe> [args…]), executing the canonical just <module>::<recipe> command internally. Aliases dispatch as x ship.

Documenting workflows

Menu entries are discovery only. A useful workflow doc covers prerequisites, arguments, worked examples, effects, and troubleshooting — write that in the project's docs pages or README (see /prelude-docs), and mirror the worked invocations with one [metadata('just <recipe> <example>')] line each so the menu details pane shows them.

Verify (no source checkout assumed)

Read the recipe before running anything: just evaluates backticks when the file loads, so even --dry-run can execute commands. Then, inside the shell:

just --summary                  # new recipe listed
just --dump --dump-format json  # the exact payload the menu imports
x --list                        # module appears as one row; children indented
just --dry-run <recipe> [args…] # after inspection: prints lines without running them
x <recipe>                     # exercise a safe no-argument recipe

References: Prelude import guide — nix run github:darkmatter/prelude#skill -- guide command-conventions; just manual — https://github.com/casey/just. Initial flake wiring: /prelude-install.