featbit-python-sdk

# FeatBit Python Server-Side SDK

Expert guidance for integrating the FeatBit Python Server-Side SDK in backend applications. This skill is based on the official SDK README and keeps details in reference files for quick navigation.

## Activates When

- The user asks about FeatBit Python SDK setup, usage, or troubleshooting.
- The user mentions `fbclient`, `FBClient`, `variation`, `variation_detail`, or `flag_tracker`.
- The user needs server-side feature flag evaluation in Python (Flask, Django, FastAPI, etc.).

## Overview

Use this SDK to evaluate feature flags on the server. The SDK syncs flag data via websocket and stores it in memory by default. If you need a custom data source, use offline mode with bootstrap JSON.

## Core Knowledge Areas

### 1. Data Synchronization

- Websocket sync keeps local data updated (average sync < 100 ms).
- The connection can be interrupted but resumes automatically after outages.
- Offline mode disables remote sync; use bootstrap JSON if needed.

### 2. Installation and Prerequisites

- Install: `pip install fb-python-sdk` (Python 3.6–3.11).
- Required values: `env_secret`, `event_url`, `streaming_url`.
- Official FAQ: environment secret + SDK URLs.

### 3. Initialization and Client Lifecycle

- Preferred pattern: call `set_config(...)`, then `get()` for a singleton client.
- Direct instantiation: `FBClient(Config(...), start_wait=15)`.
- Async readiness: `client.update_status_provider.wait_for_OKState()`.

### 4. Evaluation and All Flags

- Evaluate: `variation()` for value, `variation_detail()` for value + reason.
- All flags: `get_all_latest_flag_variations(user)`.
- Defaults are returned when SDK is not initialized or keys are invalid.

### 5. User Model

- Use a dict with required `key` and `name`.
- Add custom properties (string, number, boolean).

### 6. Flag Change Tracking

- `flag_tracker.add_flag_value_maybe_changed_listener(...)`.
- `flag_tracker.add_flag_value_changed_listener(...)`.

### 7. Offline Mode and Bootstr