Production mode

Restrict fallow’s dead code analysis to production code by excluding test files, devDependencies, and type-only imports.

Production mode restricts analysis to code that ships to users, ignoring test and development files.

fallow dead-code --production

Or set it in your config:

// .fallowrc.json
{
  "production": true
}

What changes in production mode

Behavior	Default	Production
Test files (*.test.*, *.spec.*, __tests__/)	Included	Excluded
Story files (*.stories.*)	Included	Excluded
Mock files (__mocks__/)	Included	Excluded
Package.json scripts analyzed	All	Only start, build, serve, preview, prepare, prepublishOnly, postinstall, and pre/post lifecycle hooks for start, build, serve, install
Unused devDependencies	Reported	Skipped
Type-only dependencies	Not flagged	Flagged (should be devDependencies)

$ fallow dead-code --production

● Unused exports (2)
  src/utils/format.ts
    :12 formatCurrency
    :28 formatPercentage
  Exported symbols with zero references — https://docs.fallow.tools/explanations/dead-code#unused-exports

● Unused dependencies (1)
  moment
  Packages in dependencies never imported — https://docs.fallow.tools/explanations/dead-code#unused-dependencies

● Type-only dependencies (1)
  zod  →  move to devDependencies (only imported via 'import type')
  Production dependencies only used as types — https://docs.fallow.tools/explanations/dead-code#type-only-dependencies

✗ 4 issues (19ms, production mode, 623/847 files)

Type-only dependency detection

In production mode, fallow detects dependencies that are only imported via import type:

import type { Config } from 'some-package';  // Type-only, erased at runtime

These packages belong in devDependencies since types are erased at runtime and don’t need to be installed in production.

In monorepos, production mode catches dependencies that should be devDependencies, keeping each package’s install footprint minimal.

See also

CI Integration

Use production mode in your CI pipeline for lean, fast checks.

Rules & Severity

Control which issue types are errors, warnings, or disabled.