The basics, done carefully

Small things decide whether a tool feels solid: what a bare command
does, what happens in a pipe, and how the CI log reads. Here is how vx
handles each.

Run what you mean

$ cd packages/web && vx run build   # the project you stand in
┌─ @demo/web#build > $ mkdir -p dist && sleep 0.3 && cp src/index.ts dist/index.js
└─ @demo/web#build ── (1ms) up-to-date

$ vx run build --all                # every project that declares build
$ vx run @demo/api#test             # one task, from anywhere
$ vx run build test lint --all      # several at once, one graph

No picker in a pipe

On a terminal, a bare vx run opens a picker. In a pipe, a script or an
agent's shell there is nobody to pick, so vx lists the tasks and exits:

$ vx run | cat
vx run: missing task name (stdin is not a TTY, so no picker; tasks here: build, test)

Off a terminal the live progress region is gone too. The log gets plain
lines that read the same in a file.

One fold per task on GitHub Actions

On Actions, each task's block is wrapped in a log group with its outcome
and time, so a long run collapses to one line per task:

$ vx run test --filter @demo/api
::group::@demo/api#build (success 312ms)
┌─ @demo/api#build > success
$ mkdir -p dist && sleep 0.3 && cp src/index.ts dist/index.js
└─ @demo/api#build ── (312ms) success
::endgroup::

A failed task stays open and adds an error annotation instead, such as
failed (exit 137, 128 + SIGKILL). A task's own output is fenced off,
so a line it prints can never be read as a workflow command.

Colors that listen

Output is truecolor on a terminal and plain elsewhere. NO_COLOR turns
it off. FORCE_COLOR turns it on, except FORCE_COLOR=0 and
FORCE_COLOR=false, which mean off, the way chalk and Node read them.

Packages shipped as source

A package with no build step still matters to the packages that use it.
So a project that declares no build gets one: a group with
dependsOn: ['^build'], keyed on the project's files, that runs nothing.
Edit that package, and its dependents' keys change, so --affected
reaches them.

Every flag is in the CLI reference.

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Originally published on the vx blog. vx is an MIT task runner and build cache for JS monorepos: vznjs.github.io/vx · GitHub.

_{Written with AI assistance.}