Function getTimeRelativeEarlyWarning

src/services/claudeAiLimits.ts:301–340

* Check if time-relative early warning should be triggered for a rate limit type. * Fallback when server doesn't send surpassed-threshold header. * Returns ClaudeAILimits if thresholds are exceeded, null otherwise.

(
  headers: globalThis.Headers,
  config: EarlyWarningConfig,
  unifiedRateLimitFallbackAvailable: boolean,
)

 * Returns ClaudeAILimits if thresholds are exceeded, null otherwise.
 */
function getTimeRelativeEarlyWarning(
  headers: globalThis.Headers,
  config: EarlyWarningConfig,
  unifiedRateLimitFallbackAvailable: boolean,
): ClaudeAILimits | null {
  const { rateLimitType, claimAbbrev, windowSeconds, thresholds } = config

  const utilizationHeader = headers.get(
    `anthropic-ratelimit-unified-${claimAbbrev}-utilization`,
  )
  const resetHeader = headers.get(
    `anthropic-ratelimit-unified-${claimAbbrev}-reset`,
  )

  if (utilizationHeader === null || resetHeader === null) {
    return null
  }

  const utilization = Number(utilizationHeader)
  const resetsAt = Number(resetHeader)
  const timeProgress = computeTimeProgress(resetsAt, windowSeconds)

  // Check if any threshold is exceeded: high usage early in the window
  const shouldWarn = thresholds.some(
    t => utilization >= t.utilization && timeProgress <= t.timePct,
  )

  if (!shouldWarn) {
    return null
  }

  return {
    status: 'allowed_warning',
    resetsAt,
    rateLimitType,
    utilization,
    unifiedRateLimitFallbackAvailable,
    isUsingOverage: false,
  }
}

/**
 * Get early warning limits using header-based detection with time-relative fallback.