Chinese calendar boundary queries with exact answer sets and language model outputs

This dataset contains 180 constructed Chinese calendar-boundary queries, 36 equivalent UTC timestamp representations, and 792 visible responses collected from two official DeepSeek services on 21 September 2026. Every query supplies its admissible rules and temporal domain. Exact reference answers enumerate all possible output-year labels and their uniqueness. All 792 scheduled formal responses were complete, schema-valid and correct under these definitions. This fixed collection does not estimate service reliability or evaluate divination predictions. Four engineering-only requests using invented 2099 examples are retained separately and excluded from the formal data. The archive includes raw request payloads and visible answers, collection metadata, frozen task and analysis code, two computational reference implementations, source URL and checksum records, strict scoring, figures, English prompt documentation, and offline reuse examples. It contains no personal birth records, credentials, internal reasoning text or third-party full-text PDFs. Computational checks are AI-assisted; no independent human annotation is claimed. Original data and documentation are offered under CC BY 4.0 to the extent rights subsist; original code is under MIT, as specified by the component-level license files. The author has reviewed the accompanying manuscript and approved its account of the dataset, limitations and AI assistance.