---
description: Runtime configuration, feature flags, environment variables, and typed config rules
alwaysApply: true
---

# Configuration Management

Configuration changes product behavior. Treat config as code, validate it, and make ownership explicit.

## Config Design
- Separate build-time config from runtime config.
- Validate required configuration at startup with typed schemas and clear failure messages.
- Use safe defaults only when they are genuinely safe for every environment.
- Do not scatter raw environment variable reads across the codebase. Centralize config loading.

## Feature Flags
- Every feature flag needs owner, purpose, default, rollout plan, cleanup plan, and expiration condition.
- Flags must fail safe when config is unavailable.
- Avoid long-lived flags that create permanent parallel behavior.
- Test both enabled and disabled paths for risky flags.

## Environment Management
- Keep dev, staging, and production configuration isolated.
- Do not use production secrets, endpoints, or customer data in local or test environments.
- Document required environment variables, allowed values, and examples.
- Configuration changes that affect deployment need release notes and rollback steps.

## Secrets
- Secrets are not configuration files. Use approved secret managers and runtime injection.
- Never log secret values, tokens, connection strings, or signed URLs.
- Rotate secrets when access scope, ownership, or exposure risk changes.