Tools and file types

vfor does not format or minify anything itself. For every file it looks up the extension in a fixed, ordered list of external tools and runs the first one that is installed. The lists are defined in ToolManager._setup_tool_commands() in src/vexy_formi/tools.py.

How a tool is chosen

1. Take the file's extension in lower case, for example .js.
2. Walk the list for that extension and operation from top to bottom.
3. Skip tools that are not installed. A tool counts as installed when which <tool> (where on Windows) finds it, or when <tool> --version exits with 0.
4. Run the first installed tool on the file.
5. If it fails, run the next installed tool in the list. If every tool fails, the file fails with All <operation> tools failed - followed by each tool's error.

A tool that exits with an error whose message suggests a temporary problem (for example resource temporarily unavailable or device busy) is retried up to two more times. Each tool run has a 30-second time limit.

The order is fixed. The preferred_*_tool settings in Configuration are read but do not change it in this version.

Format

vfor fmt handles these extensions. {file} is the file being processed; every command rewrites it in place.

Extension	Tools, in order of preference	Command
.py	ruff, black	ruff format {file} · black {file}
.js, .ts	biome, prettier, dprint	biome format --write {file} · prettier --write {file} · dprint fmt {file}
.jsx, .tsx	biome, prettier	as above
.css, .scss	biome, prettier	as above
.html	prettier, biome	as above
.json	biome, prettier, jq	as above · jq . {file}
.toml	taplo, dprint	taplo fmt {file} · dprint fmt {file}
.yaml, .yml	prettier, yq	prettier --write {file} · yq -i e . {file}
.md	dprint, prettier	dprint fmt {file} · prettier --write {file}

.htm and .jsonc are not formatted.

Minify

vfor mini handles these extensions.

Extension	Tools, in order of preference	Command
.js	esbuild, swc, terser	esbuild {file} --minify --outfile={file} · swc {file} --minify -o {file} · terser {file} -c -m -o {file}
.ts, .jsx, .tsx	esbuild, swc	as above
.css	lightningcss, biome	lightningcss {file} -o {file} --minify · biome format {file} --write
.scss	lightningcss	as above
.html, .htm	html-minifier-terser	html-minifier-terser {file} -o {file} --collapse-whitespace --remove-comments
.json	jq	jq -c . {file}, output written back to the file
.jsonc	biome	biome format {file} --write

Two entries are not real minifiers. For .css without lightningcss, and for .jsonc, the tool is biome format, which reformats the file and may make it larger.

Python, Markdown, TOML and YAML files are never minified.

The tool list in vfor tools

Tool	Type	Written in	Formats
esbuild	minifier	Go	JS, TS
swc	minifier	Rust	JS, TS
biome	formatter	Rust	JS, TS, JSON, CSS
ruff	formatter	Rust	Python
lightningcss	minifier	Rust	CSS
taplo	formatter	Rust	TOML
dprint	formatter	Rust	Multiple
terser	minifier	Node.js	JS
prettier	formatter	Node.js	Multiple
black	formatter	Python	Python
jq	processor	C	JSON
yq	processor	Go	YAML
html-minifier-terser	minifier	Node.js	HTML

Tool settings

vfor passes no settings of its own to the tools; the commands above are run exactly as shown, from the directory where you started vfor. Each tool finds and reads its own configuration files the way it normally does.

dprint refuses to run without a configuration file. vfor install writes a starter dprint.json into the current directory; you can also run dprint init.

The tool cache

Each tool check starts a subprocess, so vfor caches the results in ~/.cache/vfor/tool_cache.json:

• The cache is valid for one hour.
• It is discarded early when PATH, HOME, VIRTUAL_ENV or NODE_PATH changes.
• On a cache miss, only ruff, biome, prettier, black and esbuild are checked at once; other tools are checked the first time a file needs them.
• If a tool disappears between the check and the run, it is marked unavailable in the cache.

Delete the file to force a fresh check.