A 503 from the issuer's discovery endpoint made `serve` exit and the pod restart. New now retries discovery 5 times (2+4+8+16 s back-off, ~30 s) before failing as before; a cancelled ctx ends the back-off at once. WithDiscoveryRetry lets tests shrink the schedule. Closes #59 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>