Question 1

How do I add a new feature flag to a Node.js Express server?

Accepted Answer

Add the env var read in the relevant server file, gate the route or service logic with an early return or fallback, document it in docs/LAUNCH_CONFIG.md, add it to .env.example, and write tests covering both enabled and disabled paths.

Question 2

How do I expose a feature flag to a React client safely?

Accepted Answer

Add the boolean to the AuthUserResponse type in packages/shared/src/api.ts and resolve it in buildAuthUserResponse.ts so the client reads it from /api/auth/user. The client must never gate UI on a local env var.

Question 3

How do I kill-switch a payment feature during an incident?

Accepted Answer

Set PAYMENTS_ENABLED=false and restart or redeploy the server. Verify /api/readyz still returns 200, confirm payment routes return 503 with code PAYMENTS_DISABLED, and check the client shows a maintenance message.

Question 4

Why does a feature work locally but not in production?

Accepted Answer

The flag is likely unset in production or has a different default than your local environment. Check docs/LAUNCH_CONFIG.md and the deployed env values, since defaults must be safe for production.

Question 5

When should I not use a feature flag approach?

Accepted Answer

Do not use this skill when implementing the feature logic itself, handling pure auth policy or RBAC questions, or adding an LLM call. Those belong to the domain, auth, or LLM integration skills respectively.

feature-flags-launch-config

SYSTEM DOCUMENTATION & REQUIREMENTS

Frequently Asked Questions about feature-flags-launch-config

Related Skills

shared-env-contract

grafana-dashboards

llm-observability

ai-core/adapter-configuration