Function fetchAndLoadPolicyLimits

src/services/policyLimits/index.ts:432–495

* Fetch and load policy limits with file caching * Fails open - returns null if fetch fails and no cache exists

()

 * Fails open - returns null if fetch fails and no cache exists
 */
async function fetchAndLoadPolicyLimits(): Promise<
  PolicyLimitsResponse['restrictions'] | null
> {
  if (!isPolicyLimitsEligible()) {
    return null
  }

  const cachedRestrictions = loadCachedRestrictions()

  const cachedChecksum = cachedRestrictions
    ? computeChecksum(cachedRestrictions)
    : undefined

  try {
    const result = await fetchWithRetry(cachedChecksum)

    if (!result.success) {
      if (cachedRestrictions) {
        logForDebugging('Policy limits: Using stale cache after fetch failure')
        sessionCache = cachedRestrictions
        return cachedRestrictions
      }
      return null
    }

    // Handle 304 Not Modified
    if (result.restrictions === null && cachedRestrictions) {
      logForDebugging('Policy limits: Cache still valid (304 Not Modified)')
      sessionCache = cachedRestrictions
      return cachedRestrictions
    }

    const newRestrictions = result.restrictions || {}
    const hasContent = Object.keys(newRestrictions).length > 0

    if (hasContent) {
      sessionCache = newRestrictions
      await saveCachedRestrictions(newRestrictions)
      logForDebugging('Policy limits: Applied new restrictions successfully')
      return newRestrictions
    }

    // Empty restrictions (404 response) - delete cached file if it exists
    sessionCache = newRestrictions
    try {
      await unlink(getCachePath())
      logForDebugging('Policy limits: Deleted cached file (404 response)')
    } catch (e) {
      if (isNodeError(e) && e.code !== 'ENOENT') {
        logForDebugging(
          `Policy limits: Failed to delete cached file - ${e.message}`,
        )
      }
    }
    return newRestrictions
  } catch {
    if (cachedRestrictions) {
      logForDebugging('Policy limits: Using stale cache after error')