Errors

Every error response is JSON with a stable, machine-readable shape:

{
  "error": "Unsupported format: gif",
  "code": "UNSUPPORTED_FORMAT"
}

Responses are sent with Cache-Control: no-cache, no-store, must-revalidate so intermediaries never cache a failure.

Error codes

Code	HTTP status	Meaning
EMPTY_URL	400	No source URL was provided after /img/.
UNSUPPORTED_FORMAT	400	f/format was not one of auto, webp, avif.
UNSUPPORTED_CONTENT_TYPE	400	The origin responded with a non-image Content-Type.
IMAGE_NOT_FOUND	404	The origin returned 404 for the source URL.
SIZE_EXCEEDED	413	The source image exceeds the configured size limit.
CIRCUIT_BREAKER_OPEN	503	Too many recent failures fetching this origin; requests are temporarily short-circuited.
UPSTREAM_TIMEOUT	504	The origin did not respond in time.
INVALID_FIT_MODE	400	fit was not one of the supported values.
INVALID_POSITION	400	position/pos was not one of the supported values.
INVALID_BLUR	400	blur was outside the 1–100 range.
INVALID_ROTATION	400	rotate/rot was not 0, 90, 180, or 270.