Configuration

FlagLint reads the first matching config file from:

.flaglintrc
.flaglintrc.json
flaglint.config.json

Use --config <path> to pass a specific file.

Example

{
  "include": ["**/*.{ts,js}"],
  "exclude": ["**/node_modules/**", "**/dist/**"],
  "provider": "launchdarkly",
  "minFileCount": 0,
  "wrappers": ["evaluateFlag"],
  "openFeatureClientBindings": [
    {
      "importName": "openFeatureClient",
      "modulePatterns": ["**/platform/feature-flags"]
    }
  ]
}

Fields

Field	Type	Default	Purpose
include	string[]	["**/*.{ts,tsx,js,jsx}"]	Files to scan.
exclude	string[]	common build/test output	Files to skip.
provider	"launchdarkly"	"launchdarkly"	Provider scope. Currently only "launchdarkly" is supported — other values exit 2.
minFileCount	number	0	Optional local source review heuristic.
wrappers	(string | WrapperObject)[]	[]	Wrapper functions to detect as flag evaluations. Accepts string names or object form (see below).
openFeatureClientBindings	string[]	[]	Imported shared client allowlist for migrate --apply.
reportTitle	string (optional)	unset	Optional report title injected into HTML and Markdown reports.
outputDir	string	"."	Directory for generated report files.

Wrappers — String and Object Form

The wrappers field accepts two forms, which can be mixed in the same array.

String form — any call to a function with that name is treated as a flag evaluation:

{
  "wrappers": ["evaluateFlag", "getFeature"]
}

Object form — the call is only detected when the function is imported from a specific package, preventing false positives from unrelated functions with the same name:

{
  "wrappers": [
    "evaluateFlag",
    {
      "import": "my-feature-sdk",
      "function": "getFlag",
      "flagKeyArgument": 0
    }
  ]
}

Object form fields:

Field	Purpose
import	The package name that must be imported for this call to be detected.
function	The exported function name to detect.
flagKeyArgument	Zero-based index of the argument that holds the flag key.

With the example above, getFlag("my-flag-key", ctx) is detected only when getFlag is imported from my-feature-sdk. A getFlag call imported from any other package is ignored.

Feedback

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• Report an unsupported pattern
• Next: Report Formats

OpenFeature Client Bindings

openFeatureClientBindings tells flaglint migrate --apply which variables in your code hold an OpenFeature client. When applying transformations, FlagLint substitutes LD SDK evaluation calls with the corresponding OpenFeature client method calls — but only when it can identify the client variable to substitute.

Each entry is a variable name (not a package name, not a file path) that FlagLint should treat as an OpenFeature client.

Example

Your application code:

import openFeatureClient from './platform/of-client'

const value = openFeatureClient.getBooleanValue('my-flag', false)

Your config:

{
  "openFeatureClientBindings": ["openFeatureClient"]
}

With this configured, migrate --apply can generate the correct OpenFeature replacement call. Without it, files that use an imported client are listed in the “skipped” output.

Multiple bindings

If different parts of your codebase use different variable names for the OpenFeature client, list all of them:

{
  "openFeatureClientBindings": ["openFeatureClient", "featureClient", "ofClient"]
}

Difference from wrappers

openFeatureClientBindings is for the OpenFeature client used in migration output — it tells FlagLint what to generate, not what to detect. wrappers is for existing LD-compatible wrappers — it tells FlagLint what to detect as flag evaluations in your current code.