Ab Testing Implementation

• Use a threshold-array remote flag value for production defaults.
• Keep reused variants or metadata centralized in a config module when multiple files need the same definitions.
• Keep analytics mappings background-safe in shared modules so background MetaMetrics code can import them without depending on ui/.
• Use the same experiment key format as mobile: {teamName}{ticketId}Abtest{TestName}.

const experiment = useABTest('swapsSWAPS4135AbtestNumpadQuickAmounts', {
  control: { buttons: [25, 50, 75, 'MAX'] },
  treatment: { buttons: [50, 75, 90, 'MAX'] },
});

const activeABTests = experiment.isActive
  ? [
      {
        key: 'swapsSWAPS4135AbtestNumpadQuickAmounts',
        value: experiment.variantName,
      },
    ]
  : undefined;

6. Update tests and fixtures when behavior or flag plumbing changes.
   • If you add or modify the shared analytics registry/enricher, add unit coverage there and in the MetaMetrics controller path.
   • Register every new remote A/B test flag in test/e2e/feature-flags/feature-flag-registry.ts with the production default threshold-array JSON value.
   • Use test overrides such as manifestFlags.remoteFeatureFlags or FixtureBuilder.withRemoteFeatureFlags(...) when a test needs deterministic assignment.
   • If the change is copy-only or config-only, you may skip new tests with a brief rationale.
7. Run the A/B compliance checker using the repository's current supported invocation and report the result.
   • Checker path: .agents/skills/ab-testing-implementation/scripts/check-ab-testing-compliance.ts

# Current pre-commit / local implementation example
node --import tsx .agents/skills/ab-testing-implementation/scripts/check-ab-testing-compliance.ts --staged

# Current review-mode / explicit file set example
node --import tsx .agents/skills/ab-testing-implementation/scripts/check-ab-testing-compliance.ts --files app/path/to/file.ts,test/path/to/file.spec.ts --base origin/main

Review Checklist

• Confirm useABTest always has a control variant.
• Confirm Experiment Viewed is not emitted manually when useABTest is in use.
• Confirm business events use active_ab_tests rather than ab_tests.
• Confirm new automatic enrichment mappings live in background-safe shared modules rather than ui/-only config files.
• Confirm E2E flag registration and local test overrides remain production-accurate.
• Confirm the compliance checker result is included in the final response.

Related Files

• ui/hooks/useABTest.ts
• ui/hooks/useABTest.test.ts
• shared/lib/ab-testing/resolve-ab-test-assignment.ts
• shared/lib/ab-testing/ab-test-analytics.ts
• ui/selectors/remote-feature-flags.ts
• app/scripts/controllers/metametrics-controller.ts
• test/e2e/feature-flags/feature-flag-registry.ts

Use docs/ab-testing.md only when you need deeper background, additional examples, FAQ answers, or local override guidance beyond this workflow.