platformOS Check - Development Tool

platformOS Check

platformOS Check is a Node.js-based linter and language server for platformOS Liquid templates. It is part of the platformos-tools monorepo and is bundled with pos-cli.

Installation

Install pos-cli globally via npm — platformOS Check and the Language Server are included:

npm install -g @platformos/pos-cli

You can also install the linter as a standalone package for use in build pipelines:

npm install --save-dev @platformos/platformos-check-node

IDE Integration

Install the platformOS Check extension for VS Code to get inline diagnostics, hover documentation, and code actions directly in your editor. The extension uses the same Language Server bundled with pos-cli.

CLI Usage

Run the linter on your project:

pos-cli check run [path]

Available options:

Flag	Description
-a	Enable automatic fixing of offenses
-f <format>	Output format: text (default) or json
-s, --silent	Only show errors, no success messages

Initialize a .platformos-check.yml configuration file with all available settings:

pos-cli check init

Download the latest platformOS Liquid documentation used by the linter:

pos-cli check update-docs

Start the Language Server Protocol (LSP) server for IDE integration:

pos-cli lsp

Configuration

You can configure platformOS Check to override default check options, enable or disable specific checks. You can make these changes using a config file, disable checks using comments, or selectively run checks using command line flags.

Config file

Add a .platformos-check.yml file to the root of your project to override check defaults. The easiest way to create one is by running pos-cli check init, which generates a config file with all available settings commented out for reference.

The config file supports the following top-level settings:

Setting	Description
extends	Base configuration to extend. Available presets: platformos-check:recommended (default), platformos-check:all, platformos-check:nothing. You can also extend another YAML config file or an npm package.
root	If your app/modules aren't in the root directory, you can provide a relative root path for finding the platformOS app files.
ignore	Exclude directories from platformOS Check. Useful if you use private modules and do not have access to the files.
require	Paths to custom check modules (JS files or npm packages). See Writing custom checks.
check settings	For each check, set enabled to true or false, set the check severity, set specific ignore files and paths, and configure any other check-specific options.

Example config file

# Extend the recommended preset (this is the default if omitted)
extends:
  - platformos-check:recommended

# Ignore directories
ignore:
  - node_modules/**
  - modules/third-party-private-module/**

# Paths to custom check modules
require:
  - ./my-custom-checks/index.js

# Disable a check
MissingPartial:
  enabled: false

# Change severity and configure options for a check
UnusedAssign:
  enabled: true
  severity: error

# Configure a check with custom options
MissingPartial:
  enabled: true
  severity: warning
  ignore:
    - modules/legacy/**
  ignore_missing:
    - shared/deprecated-*

Check severity

The check severity indicates the relative importance of a check. Severity levels are:

Severity	Description
error	Critical issues that indicate bugs or broken functionality
warning	Issues that should be addressed but don't break functionality
info	Style and best practice suggestions

For backwards compatibility, suggestion (maps to warning) and style (maps to info) are also accepted in configuration files.

When running pos-cli check run, the process exits with code 1 if any offenses are found.

Disable checks using Liquid comments

You can disable all checks or specific checks using comments. You can disable checks for a specific section of your app code, or for an entire file.

Disable all checks for a section of your file:

{% # platformos-check-disable %}
{% assign x = 1 %}
{% # platformos-check-enable %}

Disable a specific check by including it in the comment:

{% # platformos-check-disable UnusedAssign %}
{% assign x = 1 %}
{% # platformos-check-enable UnusedAssign %}

Disable multiple checks by including them as a comma-separated list:

{% # platformos-check-disable UnusedAssign,UndefinedObject %}
{% assign x = 1 %}
{% # platformos-check-enable UnusedAssign,UndefinedObject %}

Disable checks for the entire document by placing the comment on the first line:

{% # platformos-check-disable MissingPartial %}
{% render 'legacy-partial' %}

Available checks

The following checks are available in the platformos-check:recommended preset:

Check	Default Severity	Description
DeprecatedFilter	warning	Reports usage of deprecated Liquid filters
DeprecatedTag	warning	Reports usage of deprecated Liquid tags
DuplicateFunctionArguments	warning	Reports duplicate arguments in function calls
DuplicateRenderPartialArguments	warning	Reports duplicate arguments in render tags
GraphQLCheck	error	Validates GraphQL syntax
GraphQLVariablesCheck	error	Validates GraphQL variables
ImgWidthAndHeight	error	Requires width and height on img tags
InvalidHashAssignTarget	error	Reports invalid hash assign targets
JSONSyntaxError	error	Reports JSON syntax errors
LiquidHTMLSyntaxError	error	Reports Liquid/HTML syntax errors
MatchingTranslations	error	Validates translation keys match across locales
MetadataParamsCheck	error	Validates metadata parameters
MissingAsset	error	Reports references to missing assets
MissingPartial	error	Reports references to missing partials
OrphanedPartial	warning	Reports partials that are not referenced anywhere
ParserBlockingScript	error	Reports scripts that block HTML parsing
TranslationKeyExists	error	Reports usage of non-existent translation keys
UnclosedHTMLElement	warning	Reports unclosed HTML elements
UndefinedObject	warning	Reports usage of undefined variables
UniqueDocParamNames	error	Reports duplicate @param names in LiquidDoc
UnknownFilter	error	Reports usage of unknown Liquid filters
UnknownProperty	error	Reports usage of unknown properties
UnrecognizedRenderPartialArguments	warning	Reports unrecognized arguments in render tags
UnusedAssign	warning	Reports assigned but unused variables
UnusedDocParam	warning	Reports @param tags for unused parameters
ValidDocParamTypes	error	Validates @param type annotations
ValidHTMLTranslation	warning	Validates HTML in translations
ValidJSON	error	Validates JSON file contents
ValidRenderPartialArgumentTypes	warning	Validates argument types passed to partials
VariableName	warning	Enforces variable naming conventions (default: snake_case)

Writing custom checks

You can extend platformOS Check with custom checks written in JavaScript. Custom checks are loaded via the require field in your .platformos-check.yml config file, or auto-discovered from npm packages named platformos-check-* or @your-org/platformos-check-* in your node_modules.

Custom check structure

A custom check module must export a checks array containing check definitions. Each check definition has a meta object describing the check and a create function that returns visitor methods.

Create a file, e.g. my-custom-checks/index.js:

const NoHardcodedStrings = {
  meta: {
    code: 'NoHardcodedStrings',
    name: 'No hardcoded strings in HTML',
    docs: {
      description: 'Encourages use of translations instead of hardcoded strings.',
      recommended: false,
    },
    // SourceCodeType: 'LiquidHtml' for Liquid files, 'JSON' for JSON, 'GraphQL' for GraphQL
    type: 'LiquidHtml',
    // Severity: 0 = error, 1 = warning, 2 = info
    severity: 1,
    schema: {},
    targets: [],
  },

  create(context) {
    return {
      async TextNode(node) {
        const text = node.value.trim();
        if (text.length > 0 && /[a-zA-Z]{3,}/.test(text)) {
          context.report({
            message: `Consider using a translation key instead of hardcoded text: "${text.substring(0, 50)}"`,
            startIndex: node.position.start,
            endIndex: node.position.end,
          });
        }
      },
    };
  },
};

module.exports = {
  checks: [NoHardcodedStrings],
};

Then reference it in your .platformos-check.yml:

require:
  - ./my-custom-checks/index.js

# Enable and configure your custom check
NoHardcodedStrings:
  enabled: true
  severity: warning

Visitor methods

The create function receives a context object and returns an object with visitor methods. The available visitor methods depend on the source code type:

For Liquid files (type: 'LiquidHtml'):

• Node type methods like LiquidTag, LiquidVariable, HtmlElement, HtmlRawNode, TextNode, VariableLookup, AssignMarkup, etc.
• Exit methods: append :exit to any node type (e.g. "LiquidTag:exit")
• onCodePathStart(file) — called before traversing a file
• onCodePathEnd(file) — called after traversing a file

The context object provides:

• context.report({ message, startIndex, endIndex, fix?, suggest? }) — report an offense
• context.file — the current source code file
• context.settings — check-specific settings from the config
• context.toRelativePath(uri) / context.toUri(relativePath) — path utilities
• context.fileExists(uri) — check if a file exists
• context.getDefaultTranslations() — access translation data

Publishing custom checks as npm packages

If you name your npm package following the convention platformos-check-* or @your-org/platformos-check-*, it will be auto-discovered when installed in the project's node_modules — no require entry needed in the config.