bianhaifeng789-hue/skills-experimental/enhanced-telemetry-feature-gate

Enhanced Telemetry Feature Gate Pattern

Source

Claude Code: utils/telemetry/sessionTracing.ts (isEnhancedTelemetryEnabled)

Pattern

Feature gate check: env var override > ant build > GrowthBook gate.

Code Example

import { feature } from 'bun:bundle'
import { getFeatureValue_CACHED_MAY_BE_STALE } from '../../services/analytics/growthbook.js'

/**
 * Check if enhanced telemetry is enabled.
 * Priority: env var override > ant build > GrowthBook gate
 */
export function isEnhancedTelemetryEnabled(): boolean {
  if (feature('ENHANCED_TELEMETRY_BETA')) {
    const env =
      process.env.CLAUDE_CODE_ENHANCED_TELEMETRY_BETA ??
      process.env.ENABLE_ENHANCED_TELEMETRY_BETA

    // Env var override: explicit true/false
    if (isEnvTruthy(env)) {
      return true
    }
    if (isEnvDefinedFalsy(env)) {
      return false
    }

    // No env override - check ant build or GrowthBook
    return (
      process.env.USER_TYPE === 'ant' ||
      getFeatureValue_CACHED_MAY_BE_STALE('enhanced_telemetry_beta', false)
    )
  }
  return false  // Feature flag not in build
}

/**
 * Check if any tracing is enabled (standard OR beta)
 */
function isAnyTracingEnabled(): boolean {
  return isEnhancedTelemetryEnabled() || isBetaTracingEnabled()
}

// Priority order:
// 1. CLAUDE_CODE_ENHANCED_TELEMETRY_BETA=1 → true (explicit enable)
// 2. CLAUDE_CODE_ENHANCED_TELEMETRY_BETA=0 → false (explicit disable)
// 3. USER_TYPE='ant' → true (ant build)
// 4. GrowthBook 'enhanced_telemetry_beta' → true/false (feature gate)
// 5. Else → false (feature not available)

Key Concepts

1. feature() Bundle Check: ENHANCED_TELEMETRY_BETA feature flag existence
2. Env Var Override: CLAUDE_CODE_ENHANCED_TELEMETRY_BETA first, ENABLE_* fallback
3. isEnvTruthy: 1, true, yes, on → true
4. isEnvDefinedFalsy: 0, false, no, off → false (not undefined)
5. USER_TYPE='ant': Ant build gets feature by default
6. GrowthBook Cache: getFeatureValue_CACHED_MAY_BE_STALE (async-safe)

Benefits

• User can override feature gate
• Explicit disable prevents GrowthBook override
• Ant build default enable

When to Use

• Feature gate implementation
• Env var override pattern
• Beta feature rollout

Related Patterns

• Feature Conditional Import (feature-conditional-import)
• Growthbook Service (services/analytics/growthbook.ts)
• Env Truthy/Falsy Pattern (envUtils.ts)