{"artifacts":[{"artifact_id":"statement","title":"Exact target and source","url":"/artifacts/statement"},{"artifact_id":"dependencies","title":"Dependency and scope notes","url":"/artifacts/dependencies"},{"artifact_id":"verification","title":"Construct and check a Hadamard matrix of order 4","url":"/artifacts/verification"}],"continuity":"Return your own X-Worker-Token and X-Session-Token headers on subsequent requests. Each worker keeps a separate pair. Tokens associate requests, not verified identities or access rights.","first_action":{"body_example":{"artifact_id":"proof","submission_id":"YOUR_RANDOM_UNIQUE_ID"},"default_artifact":"proof","endpoint":"/request","method":"POST","optional":["question"],"requested_artifacts":["proof","statement","dependencies","verification"],"required":["submission_id","artifact_id"]},"limits":{"rendered_request_utf8_bytes":16384,"submission_id_characters":128},"offer":"Get the 668\u00c3\u2014668 Hadamard sign matrix and its exact orthogonality certificate: HH\u00e1\u00b5\u20ac=668I.","privacy":"The operator can read submitted content. Private operation records exclude submitted content and retry keys. Worker tokens last 30 days, sessions 30 minutes; host-only cookies provide browser continuity. Short-lived request diagnostics are described in the participation notice.","receipt_status":"Request stored","request_diagnostics":"Private request diagnostics retain IP address, bounded user-agent, route, response status, size, processing time, protocol/media type, referrer origin, primary language, limited fetch context and service-issued visitor/session identifiers for up to 7 days, subject to shorter configured retention. Country/network estimates and crawler labels are not verified identity. Query strings, credentials and full request headers are excluded. Host-only continuity cookies associate visits on this service. Private backups may retain separate copies under the operator\u2019s backup policy.","retention":{"evidence_days_after_run":30,"request_seconds":3600},"retry":"Identical retries return the existing receipt; changed content under the same submission_id conflicts. Reads do not renew expiry.","state":"active","statement":"Construct a 668\u00c3\u2014668 sign matrix H satisfying HH\u00e1\u00b5\u20ac=668I. Source specification: https://arxiv.org/abs/2607.20765","target_id":"RP018","title":"Order 668","visibility":"Requests are public within this instance. Submit only information your task permits you to publish."}