[Backend] Implement Feature Flags

[gelluisaac]

Overview

Implement a feature flag system for controlled feature rollouts.

Current State

• No feature flag system
• Features are always on/off
• No A/B testing capability
• No gradual rollouts

Requirements

1. Feature Flag Features

   • Feature flag CRUD
   • Flag targeting (users, segments)
   • Flag rollouts (percentage)
   • Flag scheduling
   • Flag dependencies

2. Flag Types

   • Boolean flags
   • Multivariate flags
   • Remote config
   • A/B testing flags
   • Kill switches

3. Integration

   • Express middleware
   • Flag evaluation
   • Flag overrides
   • Flag analytics
   • Flag monitoring

4. Management

   • Admin UI for flags
   • Flag history
   • Flag audit logs
   • Flag permissions
   • Flag documentation

Technical Details

• Use feature flag library (LaunchDarkly, Unleash, or custom)
• Implement flag evaluation
• Add flag middleware
• Create flag admin interface

Files to Create/Modify

• backend/src/services/featureFlagService.ts (create)
• backend/src/models/FeatureFlag.ts (create)
• backend/src/middleware/featureFlags.ts (create)
• backend/src/routes/featureFlags.ts (create)
• backend/src/config/featureFlags.ts (create)

Acceptance Criteria

• Flags can be created
• Flag evaluation works
• Targeting works
• Rollouts work
• Admin UI works
• Analytics work
• Performance is good
• Documentation is complete

References

• LaunchDarkly: https://launchdarkly.com/
• Unleash: https://github.com/Unleash/unleash
• Feature flag best practices: https://martinfowler.com/articles/feature-toggles.html

[favourawaku]

Hi maintainer, I have experience building feature flag systems with percentage rollouts, user targeting, and admin management in Node.js/Express and would love to work on this issue.

[Hassanmovic98]

I'll design and implement a complete feature flag system: flag CRUD, targeting logic, percentage-based rollouts, and flag dependencies. I'll integrate with Express middleware for runtime evaluation, build the admin interface with flag history and audit logs, and set up analytics integration. I'll use a proven approach (Unleash or LaunchDarkly integration), implement comprehensive tests, and document the architecture.

[anoncon]

Hi I’d like to work on this issue if it’s available. I’m a full-stack Web2 & Web3 developer with solid open-source experience and can start working on it right away.

[grantfox-oss]

🦊 GrantFox — @anoncon has been assigned to this issue as part of the Official Campaign campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #189)
2. Your PR will be reviewed by the nexoraorg maintainers

Good luck! Track your progress on GrantFox.