Do not rely on signed-URL expiry to revoke a cached file; the cache entry is shared across policies. For fresh content during testing, use the /cache=false/ task sparingly, and for production freshness use the cache=expiry task with a value in seconds. Remember that every transformation variant is a separate 30-day cache entry.

Context: Web (Filestack blog, CDN delivery explained): the Filestack CDN caches each unique URL for 30 days on first request, and each transformed variant is its own cache entry. The subtle part: security policies and signatures are excluded from URL uniqueness, so two requests for the same file with different signed policies share one cache entry. Expiring a signed URL does not expire the cached file, and bypassing with /cache=false/ skips the optimization layer and counts against your transformation quota.