{
  "policy": "Each version folder under /data is immutable: a later export on the same date is published as YYYY-MM-DD.rN and never overwrites an earlier one. latest/ is a copy of the newest version.",
  "latest": "2026-10-30",
  "versions": [
    {
      "snapshot_version": "2026-10-07",
      "snapshot_date": "2026-10-07",
      "revision": 1,
      "generated_at": "2026-10-07T08:08:48.000Z",
      "supersedes": null,
      "method_version": "arc-method-2026.10",
      "stores_checked": null,
      "rows": {
        "stores": 89,
        "rails_checks": 607,
        "adoption_history": 11
      },
      "note": "First publication (Open ARC dataset, PR #62): stores, rails_checks, adoption_history.",
      "source_commit": "3ed6750"
    },
    {
      "snapshot_version": "2026-10-07.r2",
      "snapshot_date": "2026-10-07",
      "revision": 2,
      "generated_at": "2026-10-07T11:27:46.000Z",
      "supersedes": "2026-10-07",
      "method_version": "arc-method-2026.10",
      "stores_checked": null,
      "rows": {
        "stores": 89,
        "rails_checks": 607,
        "adoption_history": 11,
        "protocol_matrix": 24
      },
      "note": "Regenerated the same day: added protocol_matrix (PR #66).",
      "source_commit": "f3100e1"
    },
    {
      "snapshot_version": "2026-10-07.r3",
      "snapshot_date": "2026-10-07",
      "revision": 3,
      "generated_at": "2026-10-07T11:41:11.000Z",
      "supersedes": "2026-10-07.r2",
      "method_version": "arc-method-2026.10",
      "stores_checked": null,
      "rows": {
        "stores": 89,
        "rails_checks": 607,
        "adoption_history": 12,
        "personas": 5,
        "protocol_matrix": 24
      },
      "note": "Regenerated the same day: one stores/history definition, WebMCP not measured before the detector start, persona_a to persona_e (PR #67).",
      "source_commit": "01aa010"
    },
    {
      "snapshot_version": "2026-10-07.r4",
      "snapshot_date": "2026-10-07",
      "revision": 4,
      "generated_at": "2026-10-07T14:32:35.000Z",
      "supersedes": "2026-10-07.r3",
      "method_version": "arc-method-2026.10",
      "stores_checked": null,
      "rows": {
        "stores": 89,
        "rails_checks": 647,
        "adoption_history": 12,
        "personas": 5,
        "protocol_matrix": 24
      },
      "note": "Regenerated the same day: rails_checks gained source; directory hosts grew (PR #69).",
      "source_commit": "4375862"
    },
    {
      "snapshot_version": "2026-10-07.r5",
      "snapshot_date": "2026-10-07",
      "revision": 5,
      "generated_at": "2026-10-07T19:17:59.000Z",
      "supersedes": "2026-10-07.r4",
      "method_version": "arc-method-2026.10",
      "stores_checked": 1039,
      "rows": {
        "stores": 89,
        "rails_checks": 1044,
        "adoption_history": 12,
        "personas": 5,
        "protocol_matrix": 24
      },
      "note": "Regenerated the same day: one host set across directory, tracker, matrix and dataset; stores_checked added (PR #72).",
      "source_commit": "2346d7c"
    },
    {
      "snapshot_version": "2026-10-09",
      "snapshot_date": "2026-10-09",
      "revision": 1,
      "generated_at": "2026-10-09T15:47:44.466Z",
      "supersedes": "2026-10-07.r5",
      "method_version": "arc-method-2026.10",
      "stores_checked": 3308,
      "rows": {
        "store_answers": 3324,
        "stores": 89,
        "rails_checks": 3324,
        "adoption_history": 17,
        "personas": 5,
        "protocol_matrix": 24
      }
    },
    {
      "snapshot_version": "2026-10-09.r2",
      "snapshot_date": "2026-10-09",
      "revision": 2,
      "generated_at": "2026-10-09T15:54:03.392Z",
      "supersedes": "2026-10-09",
      "method_version": "arc-method-2026.10",
      "stores_checked": 3308,
      "rows": {
        "store_answers": 3324,
        "stores": 89,
        "rails_checks": 3324,
        "adoption_history": 17,
        "personas": 5,
        "protocol_matrix": 24
      }
    },
    {
      "snapshot_version": "2026-10-09.r3",
      "snapshot_date": "2026-10-09",
      "revision": 3,
      "generated_at": "2026-10-09T16:03:08.069Z",
      "supersedes": "2026-10-09.r2",
      "method_version": "arc-method-2026.10",
      "stores_checked": 3307,
      "rows": {
        "store_answers": 3324,
        "stores": 89,
        "rails_checks": 3324,
        "adoption_history": 17,
        "personas": 5,
        "protocol_matrix": 24
      },
      "note": "stores_checked and the protocol matrix UCP and MCP denominator corrected from 3308 to the 3307 completed store_answers rows. Percentages at one decimal are unchanged. summary.json documents attempted, completed and failed."
    },
    {
      "snapshot_version": "2026-10-12",
      "snapshot_date": "2026-10-12",
      "revision": 1,
      "generated_at": "2026-10-12T13:34:11.974Z",
      "supersedes": "2026-10-09.r3",
      "method_version": "arc-method-2026.10",
      "stores_checked": 3497,
      "rows": {
        "store_answers": 3538,
        "stores": 89,
        "rails_checks": 3538,
        "adoption_history": 29,
        "personas": 5,
        "protocol_matrix": 24
      }
    },
    {
      "snapshot_version": "2026-10-12.r2",
      "snapshot_date": "2026-10-12",
      "revision": 2,
      "generated_at": "2026-10-12T20:37:22.938Z",
      "supersedes": "2026-10-12",
      "method_version": "arc-method-2026.10",
      "stores_checked": 3497,
      "rows": {
        "store_answers": 3538,
        "stores": 89,
        "rails_checks": 3538,
        "adoption_history": 32,
        "personas": 5,
        "protocol_matrix": 24
      },
      "note": "UCP file sample of 220 listed United States stores: 125 of 190 clear answers publish a UCP file (as of 12 Oct 2026). 30 were unknown. Other stores are not recorded and are not counted as no."
    },
    {
      "snapshot_version": "2026-10-12.r3",
      "snapshot_date": "2026-10-12",
      "revision": 3,
      "generated_at": "2026-10-13T19:30:00.000Z",
      "supersedes": "2026-10-12.r2",
      "method_version": "arc-method-2026.10",
      "stores_checked": 3318,
      "rows": {
        "store_answers": 3335,
        "stores": 89,
        "rails_checks": 3335,
        "adoption_history": 32,
        "personas": 5,
        "protocol_matrix": 24
      },
      "note": "CC BY 4.0 edition of 2026-10-12.r2 with the 203 OpenStreetMap-derived rows removed and quarantined unpublished discovery-source hosts excluded. Browser tests unchanged since r2, dated 2026-10-06. protocol_matrix.csv recounted from rails_checks.csv; UCP declared is Not measured because that file does not keep HTTP status."
    },
    {
      "snapshot_version": "2026-10-30",
      "snapshot_date": "2026-10-30",
      "revision": 1,
      "generated_at": "2026-10-31T05:48:05.715Z",
      "supersedes": "2026-10-12.r3",
      "method_version": "arc-method-2026.10",
      "stores_checked": 10610,
      "rows": {
        "store_answers": 10681,
        "stores": 89,
        "rails_checks": 10681,
        "adoption_history": 60,
        "personas": 5,
        "protocol_matrix": 24
      },
      "license": "CC-BY-4.0",
      "note": "checks dated 6\u201331 Oct 2026; no light-checker rows"
    }
  ]
}