ffs.txt

Goals
- Excellent performance
- Small library sizes
- Unbloated feature set
- OSS first and foremost

---

- On/off
- Percentage rollouts (X% true, Y% false)
  - Consistent random seed
- Rulesets (e.g., regexp)
- Local flags
- Archived flags (final value + warning upon usage)

- Client config
  - URL
  - API key

- User configuration
  - unique key (required) OR anonymous (uses device-specific key) // migration?
  - email
  - name
  - language
  - custom key/value

- Frontend SDKs (remote evaluation) + Backend SDKs (local evaluation)

- Instant flag update propagation (configurable, e.g., only polling, or no foreground updates)
  - Client-side SDKs
    - Server-sent events in foreground
    - Polling in background
    - Analytics on demand
  - Server-side SDKs
    - Analytics on demand
    
Rulesets in functions (excel style)
  - Use values for args
  - Use other flags for args
  
Docker setup for server

Later
- IP address matcher (see: https://github.com/silvercar/unleash-client-kotlin/blob/master/unleash/src/main/java/com/silvercar/unleash/util/IpAddressMatcher.kt)
- Expected lifetime (see: https://docs.getunleash.io/advanced/feature_toggle_types)
- Analytics (# of requests, some request data)
- Scheduled flags (date + time)

Maybe later?
- API versioning on the client
- Environments
- Features to group flaggs
- Private user attributes (used for evaluation, but discarded from analytics)
- Test mode that crashes if flags are not explicitly set
- Test annotation that re-runs tests with flag changes
- Integrations?

Android SDK (frontend) for inspiration:
- https://launchdarkly.github.io/android-client-sdk/com/launchdarkly/sdk/android/package-summary.html
- https://docs.getunleash.io/sdks/android_proxy_sdk

Python SDK (backend) for inspiration:
- https://launchdarkly-python-sdk.readthedocs.io/en/latest/
- https://docs.getunleash.io/sdks/python_sdk