Flag Inversion

Flag inversion lets you flip a flag’s default value for specific native builds based on their bundle ID. This is useful when you have multiple app variants (e.g. internal vs. public) and want different default flag states per variant.

How it works

The invertFor.bundleId matcher compares against the ios.bundleIdentifier and android.package values in your Expo config. If there’s a match, the flag value is inverted during expo prebuild.

Example

flags.yml

mergePath: src/constants/buildFlags.ts
flags:
  internalTools:
    value: false
    invertFor:
      bundleId:
        - com.mycompany.app.internal

With this configuration:

Build variant	Bundle ID	internalTools value
Public	com.mycompany.app	false (default)
Internal	com.mycompany.app.internal	true (inverted)

The inversion happens at prebuild time when the Expo config plugin runs. It reads the bundle identifier from your Expo config and checks it against the bundleId list.

When to use this

• You maintain multiple app variants with different bundle identifiers
• Certain features should be on by default for internal builds but off for public builds (or vice versa)
• You want this to be declarative in flags.yml rather than managed through environment variables

Notes

• Inversion only applies during native builds via expo prebuild. It does not affect build-flags override during local development. Use the CLI +/- syntax to toggle flags locally.
• Both iOS bundleIdentifier and Android package are checked.