Custom Rules

You can define project-specific lint rules using the declarative rule({...}) format.

Setup

Add your rule files to the plugins array in chant.config.ts:

export default {
  lint: {
    plugins: ["./lint-rules/org-standards.ts"],
  },
};

Rule Format

Each rule is a top-level rule({...}) call:

rule({
  id: "ORG001",
  severity: "warning",
  message: "Storage resources must have versioning enabled",
  match: match.property("versioning").on(match.anyResource()),
  pattern: "true",
});

Required Fields

Field	Type	Description
id	string	Unique rule identifier
severity	"error" | "warning" | "info"	Default severity level
message	string	Diagnostic message
match	selector	Structural selector for AST nodes

Optional Fields

Field	Type	Description
pattern	string	Regex pattern the matched value must satisfy
require	string	Comma-separated list of required property names
max	number	Numeric threshold

Match Selectors

Selector	Matches
match.resource("ClassName")	new ClassName({...}) expressions
match.anyResource()	Any new expression
match.stringLiteral()	String literal values
match.exportName()	Exported declaration names
match.importSource()	Import module specifiers
match.property("name")	Object property with given key
match.exportedConst()	export const declarations

Narrow a selector with .on():

match.property("tags").on(match.resource("StorageType"))

Duplicate Detection

If a custom rule ID collides with a built-in rule, the linter reports an error at startup. Choose IDs namespaced to your organization (e.g., ORG001, ACME001).