/**
* Edge Config Integration for A/B Testing
*
* Provides runtime experiment configuration via Vercel Edge Config
* with graceful fallback to default config when unavailable.
*/
import { get } from '@vercel/edge-config';
import {
ExperimentConfig,
DEFAULT_EXPERIMENT_CONFIG,
PromptVariant,
ProgressGranularity,
ResourceDisclosure,
} from './types';
// Cache the config in memory to reduce Edge Config reads
let cachedConfig: ExperimentConfig | null = null;
let cacheTimestamp = 0;
const CACHE_TTL_MS = 60 * 1000; // 1 minute cache
/**
* Get the current experiment configuration
*
* Fetches from Vercel Edge Config with:
* - In-memory caching (1 minute TTL)
* - Graceful fallback to defaults
* - Partial config merging for incomplete Edge Config responses
*/
export async function getExperimentConfig(): Promise<ExperimentConfig> {
const now = Date.now();
// Return cached config if still valid
if (cachedConfig && now - cacheTimestamp < CACHE_TTL_MS) {
return cachedConfig;
}
try {
// Fetch from Edge Config
const edgeConfig = await get<Partial<ExperimentConfig>>('experimentConfig');
if (edgeConfig) {
// Merge with defaults to handle partial configs
cachedConfig = mergeConfig(edgeConfig);
cacheTimestamp = now;
return cachedConfig;
}
} catch (error) {
// Log error but don't throw - graceful degradation
console.warn('[experiment] Edge Config unavailable, using defaults:', error);
}
// Fallback to defaults
cachedConfig = { ...DEFAULT_EXPERIMENT_CONFIG };
cacheTimestamp = now;
return cachedConfig;
}
/**
* Merge partial Edge Config with defaults
*
* Handles cases where Edge Config has only some fields set
*/
function mergeConfig(partial: Partial<ExperimentConfig>): ExperimentConfig {
return {
promptVariant: validatePromptVariant(partial.promptVariant),
progressGranularity: validateProgressGranularity(partial.progressGranularity),
resourceDisclosure: validateResourceDisclosure(partial.resourceDisclosure),
features: {
...DEFAULT_EXPERIMENT_CONFIG.features,
...(partial.features || {}),
},
version: partial.version || DEFAULT_EXPERIMENT_CONFIG.version,
};
}
/**
* Validate prompt variant, falling back to default if invalid
*/
function validatePromptVariant(value: unknown): PromptVariant {
if (value === 'A' || value === 'B') {
return value;
}
return DEFAULT_EXPERIMENT_CONFIG.promptVariant;
}
/**
* Validate progress granularity, falling back to default if invalid
*/
function validateProgressGranularity(value: unknown): ProgressGranularity {
if (value === 'none' || value === 'phase' || value === 'detailed') {
return value;
}
return DEFAULT_EXPERIMENT_CONFIG.progressGranularity;
}
/**
* Validate resource disclosure, falling back to default if invalid
*/
function validateResourceDisclosure(value: unknown): ResourceDisclosure {
if (value === 'minimal' || value === 'standard' || value === 'extended') {
return value;
}
return DEFAULT_EXPERIMENT_CONFIG.resourceDisclosure;
}
/**
* Force refresh the config cache
*
* Useful for testing or when you know the config has changed
*/
export function invalidateConfigCache(): void {
cachedConfig = null;
cacheTimestamp = 0;
}
/**
* Check if a feature is enabled
*/
export async function isFeatureEnabled(
feature: keyof ExperimentConfig['features']
): Promise<boolean> {
const config = await getExperimentConfig();
return config.features[feature];
}
