@farmart-tech/brave-feature-core

Pure, framework-agnostic feature flag evaluation engine for the Brave Ship system.

@farmart-tech/brave-feature-core is the core domain logic for evaluating feature flags. It handles complex targeting rules, user segmentation, and consistent hashing-based rollouts. It is designed to be lightweight and portable, running in browsers, Node.js, and edge environments.

Features

• 🚀 Performance: Ultra-fast evaluation with no external network calls.
• 🎯 Targeting: Support for complex logical conditions (allOf, anyOf) and custom user attributes.
• 📈 Rollouts: Consistent hashing-based percentage rollouts and time-based step rollouts.
• 👥 Segmentation: Evaluate users against predefined segments (user lists, platforms, locations).
• 🛡️ Type-Safe: Written in TypeScript with full type definitions for all configuration models.

Installation

npm install @farmart-tech/brave-feature-core
# or
pnpm add @farmart-tech/brave-feature-core
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Quick Start

Basic Evaluation

import { Feature } from '@farmart-tech/brave-feature-core';

// 1. Define feature configuration (usually fetched from Brave Ship API/Firebase)
const featureData = {
  enabled: true,
  description: 'Enable dark mode',
  rolloutStrategy: {
    type: 'percentage',
    config: { percentage: 50 }
  }
};

// 2. Prepare evaluation context
const context = {
  deviceContext: { 
    deviceID: 'unique-device-id',
    devicePlatform: 'web',
    deviceRegisteredAt: '2024-01-01T00:00:00Z',
    environment: 'production'
  },
  userContext: { 
    userId: 'user-123',
    customAttributes: { tier: 'premium' }
  },
  localFeatureContext: { /* local storage persistence adapter */ },
  segmentContext: { get: async (name) => null },
  featureContext: { get: async (name) => null },
  conditionContext: { get: async (name) => null }
};

// 3. Evaluate
const feature = new Feature(featureData, context);
const isEnabled = await feature.getIsEnabled();

console.log(`Feature enabled: ${isEnabled}`);
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Complex Targeting with Builders

import { FeatureBuilder, ConditionBuilder } from '@farmart-tech/brave-feature-core';

const featureConfig = new FeatureBuilder()
  .setFeatureName('premium_dashboard')
  .setEnabled(true)
  .setCondition(
    ConditionBuilder.allOf(
      ConditionBuilder.condition('user.attributes.tier', '=', 'premium'),
      ConditionBuilder.condition('device.platform', 'in', ['ios', 'android'])
    )
  )
  .build();
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Documentation

Comprehensive API documentation is available at: https://fmt-feature-management.web.app/docs/feature-core/

License

MIT © FarMart