ERC-8004 agent identity registrations across 13 EVM networks — two snapshots with endpoint liveness probes

Complete populations of the ERC-8004 Identity Registry and companion Reputation Registry on 13 EVM networks, at two snapshots (mc_t1: 2026-08-10, 390,870 tokens; mc_t2: 2026-08-16, 401,149 tokens). Five linked layers per snapshot, keyed by (chain, agent_id): on-chain census at pinned blocks; structural descriptions of every resolved registration card; liveness and interface probes of every declared http(s) endpoint (33,065 distinct URLs at mc_t2) under a pre-registered specification; full mint-event history with timestamps and sampled gas receipts; reputation-registry feedback. Plus a human-annotated validation subset of 300 live endpoints (100 of them double-coded, 400 codings in total; rubric frozen before data collection). Networks: Arbitrum One, Avalanche C-Chain, Base, BNB Smart Chain, Celo, Ethereum, Gnosis, Linea, Mantle, Metis, OP Mainnet, Polygon PoS, Scroll. Registrant-authored text is described rather than reproduced. The tokenURI string, the registration card body and the probed URLs are represented by structural fields (scheme, media type, encoding, byte length) and by surrogate group ids shared between identical values; no content is masked or substituted, and every measurement in the dataset remains computable from the deposited files. Section 12 of DATA_DICTIONARY.md states the mapping, the reasoning (third-party rights, personal data, credentials that registrants published into their own metadata, and abuse surface) and what it costs. License: CC0 1.0. Collection and QA code: https://github.com/k-nikita-n/erc8004-registry-snapshots (MIT, tag v1.0.0).