platformOS Check — Available Checks

Available Checks

You can run the following checks as part of platformOS Check. Each check identifies a specific problem or a place in your code where a best practice is not being followed.

For configuration options, severity overrides, and how to disable checks per-file, see platformOS Check Configuration.

Liquid File Checks

These checks analyze the style and validity of Liquid templates, including .liquid files in app/views/pages/, app/views/partials/, and app/lib/.

Check	Severity	Description
DeprecatedFilter	warning	Reports usage of deprecated Liquid filters
DeprecatedTag	warning	Reports usage of deprecated Liquid tags
DuplicateFunctionArguments	warning	Reports duplicate argument names in {% function %} calls
DuplicateRenderPartialArguments	warning	Reports duplicate argument names in {% render %} tags
FilterArity	error	Reports a known filter called with the wrong number of arguments — platformOS raises Liquid::ArgumentError at render time
FilterWithoutEffect	warning	Reports a filter in a tag operand or argument, where the runtime never applies it and the value is used unfiltered
GraphQLVariablesCheck	error	Validates that parameters passed to {% graphql %} match the query's variable definitions
ImgWidthAndHeight	error	Requires width and height attributes on img tags to prevent cumulative layout shift
ImplicitIncludeArguments	warning	Reports a variable an {% include %}'d partial reads that the call site does not pass, and so inherits from the caller's scope — working, but invisible at the call site
InvalidWriteTarget	error	Reports a write into a container the runtime rejects — a subscript write ({% assign %}, {% hash_assign %}, {% function %}) that is neither a Hash with a key nor an Array with an index, or << against anything but an Array
JsonLiteralQuoteStyle	error	Enforces double-quoted string literals inside inline object/array literals — single quotes are not valid JSON
LiquidHTMLSyntaxError	error	Reports Liquid and HTML syntax errors
MissingAsset	error	Reports references to asset files that do not exist
MissingContentForLayout	error	Reports layouts that never output {{ content_for_layout }}, which drops the page body
MissingDocParam	error	Reports a variable a partial reads from its caller without declaring it as a @param in its {% doc %} tag, which leaves it required by the implementation and impossible to pass
MissingPage	warning	Reports links and form actions pointing to routes with no matching platformOS page
MissingPartial	error	Reports references to partial, function, or GraphQL files that do not exist
MissingRenderPartialArguments	error	Reports missing required arguments at {% render %} and {% function %} call sites, for partials that declare their parameters with a {% doc %} tag
NestedGraphQLQuery	warning	Detects {% graphql %} tags inside loop tags — the N+1 pattern — including transitive calls via {% render %} and {% function %}
ParserBlockingScript	error	Reports <script> tags without defer or async that block HTML parsing
PartialCallArguments	error	Ensures required arguments are passed to {% render %} and {% function %} call sites and no unknown arguments are passed, for partials with NO {% doc %} tag, inferring the parameter list from the partial body (formerly MetadataParamsCheck)
RequiredDocParamWithDefault	warning	Reports a parameter a {% doc %} tag declares as required that the partial then reads through the default filter, which almost always means the declaration should have been [param]
ReservedVariableName	error	Reports reserved Liquid literals (true, false, nil, null, empty, blank) used as variable names
RollbackOutsideTransaction	error	Reports a {% rollback %} reached outside a {% transaction %} block, following {% render %}, {% function %} and {% background %} calls and reporting on the call site
TranslationKeyExists	error	Reports translation keys used in templates that are not defined in the default language file
UnclosedHTMLElement	warning	Reports unbalanced HTML tags in branching Liquid code
UndefinedObject	warning	Reports references to variables that have not been defined
UniqueDocParamNames	error	Reports duplicate @param names in {% doc %} tags
UnknownFilter	error	Reports usage of Liquid filters that do not exist in the platformOS filter set
UnknownProperty	error	Reports access to properties that do not exist on variables whose structure the linter can determine — including GraphQL results and values returned from a {% function %} call
UnrecognizedRenderPartialArguments	warning	Reports arguments passed to {% render %} or {% function %} that are not declared in the partial's {% doc %} tag
UnusedAssign	warning	Reports variables assigned with {% assign %} or {% function %} that are never used
UnusedDocParam	warning	Reports @param entries in {% doc %} tags that are never used in the partial body
ValidDocParamTypes	error	Reports @param type annotations in {% doc %} tags that are not valid platformOS types
ValidFrontmatter	warning	Validates YAML frontmatter (required fields, allowed values, deprecated keys, association existence) for known platformOS file types
ValidRenderPartialArgumentTypes	warning	Reports type mismatches between arguments passed to {% render %} and the types declared in the partial's {% doc %} tag
ValidFilterArgumentTypes	warning	Reports a value passed to a Liquid filter, the piped value included, whose type contradicts the type the documentation publishes for it
ValidTagArgumentTypes	warning	Reports arguments passed to a Liquid tag whose type contradicts the type the documentation publishes for them
VariableName	warning	Enforces a consistent variable naming convention (default: snake_case)

GraphQL File Checks

These checks analyze .graphql files and validate them against the platformOS schema. Run pos-cli check update-docs to keep the local schema up to date.

Check	Severity	Description
GraphQLCheck	error	Validates GraphQL query and mutation files for syntax errors and schema conformance

YAML File Checks

These checks analyze YAML files: translations in app/translations/, and — for YAMLSyntaxError — every other YAML source the platform deploys, including app/config.yml and model schemas.

Check	Severity	Description
DuplicateYAMLKey	warning	Reports a key defined twice in one mapping, where the earlier value is silently discarded
MatchingTranslations	error	Reports translation files where keys are missing compared to the default language file
ValidHTMLTranslation	warning	Reports translation values that contain invalid HTML markup
YAMLSyntaxError	error	Reports what the YAML parser could not read — the file is rejected on deploy, which fails the whole changeset