Shipping Safely

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// Feature flag configuration with kill switch
interface FeatureConfig {
  enabled: boolean;
  rolloutPercentage: number;
  killSwitch: boolean; // Override that disables regardless of other settings
  allowedUserIds?: string[]; // For beta testing
}

const AI_FEATURE_CONFIG: FeatureConfig = {
  enabled: true,
  rolloutPercentage: 10, // 10% of users
  killSwitch: false,

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// Kill switch with local cache and fail-closed behavior
class AIKillSwitch {
  private cache: Map<string, { value: boolean; expiry: number }> = new Map();
  private readonly TTL_MS = 30000; // 30 second cache
  
  async isEnabled(feature: string, context: KillSwitchContext): Promise<boolean> {
    // Check local cache first
    const cached = this.cache.get(feature);
    if (cached && cached.expiry > Date.now()) {
      return cached.value;
    }
    

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class AICircuitBreaker {
  private state: 'closed' | 'open' | 'half-open' = 'closed';
  private failures: number[] = []; // timestamps of recent failures
  private lastStateChange: number = Date.now();
  
  private readonly config = {
    failureThreshold: 5,        // failures to trip
    failureWindowMs: 60000,     // 1 minute window
    openDurationMs: 30000,      // 30 seconds before half-open
    halfOpenRequests: 3,        // probes before closing
    costAnomalyMultiplier: 5,   // 5x normal cost = failure
    latencyThresholdMs: 10000   // 10 second timeout = failure

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import { Redis } from 'ioredis';
import { CircuitBreaker, RateLimiter, CostTracker, FeatureFlags } from './safety';

const redis = new Redis(process.env.REDIS_URL);

const safetyMiddleware = {
  flags: new FeatureFlags(redis),
  circuit: new CircuitBreaker({
    failureThreshold: 5,
    resetTimeout: 30000,
    monitorWindow: 60000
  }),

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import { Router } from 'express';
import { safetyMiddleware } from './safety';

const healthRouter = Router();

interface HealthStatus {
  status: 'healthy' | 'degraded' | 'unhealthy';
  timestamp: string;
  components: {
    featureFlags: ComponentHealth;
    rateLimiter: ComponentHealth;
    costTracker: ComponentHealth;