{
  "title": "MCP Protocol Versions - Normalized Claim Register",
  "schemaVersion": "1.0",
  "researchFreeze": "2026-08-26",
  "protocolRevision": "2026-07-28",
  "idNote": "claimId is globally namespaced; packageClaimId and packageSourceIds preserve research/7 identifiers.",
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        "S001"
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        "S054"
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      "claimId": "R7-C002",
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      "notes": "Versioning — MCP 2026-07-28",
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      "claim": "server/discover supported-version and capability advertisement.",
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        "S005"
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        "S127"
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      "notes": "Server Discovery — MCP 2026-07-28",
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        "S006"
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        "S130"
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      "notes": "Base Protocol — MCP 2026-07-28",
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        "S007"
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        "S057"
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      "notes": "Transports — MCP 2026-07-28",
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      "claimId": "R7-C008",
      "packageClaimId": "C008",
      "claim": "Current stdio process and framing behavior.",
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        "S008"
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        "S132"
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      "confidence": "VERIFIED",
      "notes": "stdio Transport — MCP 2026-07-28",
      "durability": "DURABLE"
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      "claimId": "R7-C009",
      "packageClaimId": "C009",
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        "S009"
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        "S131"
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      "notes": "Streamable HTTP — MCP 2026-07-28",
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        "S010"
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        "S133"
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      "notes": "Authorization — MCP 2026-07-28",
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      "claimId": "R7-C011",
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        "S011"
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        "S123"
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      "claimId": "R7-C012",
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      "claim": "Current resource list/read behavior, templates, caching and subscription events.",
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        "S012"
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        "S124"
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      "claimId": "R7-C013",
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        "S013"
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        "S125"
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      "confidence": "VERIFIED",
      "notes": "Prompts — MCP 2026-07-28",
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      "claimId": "R7-C014",
      "packageClaimId": "C014",
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        "S014"
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        "S126"
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      "notes": "Elicitation — MCP 2026-07-28",
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      "claimId": "R7-C015",
      "packageClaimId": "C015",
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        "S015"
      ],
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        "S058"
      ],
      "confidence": "VERIFIED",
      "notes": "The 2026-07-28 Specification Is Generally Available",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C016",
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        "S016"
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        "S053"
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      "notes": "2026-07-28 Specification Release Candidate",
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    },
    {
      "claimId": "R7-C017",
      "packageClaimId": "C017",
      "claim": "Stable release timestamp and tag.",
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      "specVersion": "2026-07-28",
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        "S017"
      ],
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        "S313"
      ],
      "confidence": "VERIFIED",
      "notes": "GitHub release 2026-07-28",
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    },
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      "claimId": "R7-C018",
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      "claim": "RC release timestamp and prerelease status.",
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        "S018"
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        "S314"
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      "notes": "GitHub release 2026-07-28-RC",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C019",
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      "claim": "Active, Deprecated and Removed states; minimum deprecation window.",
      "dateRange": "2026-05-18",
      "specVersion": "Process",
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        "S019"
      ],
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        "S315"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "SEP-2596: Specification Feature Lifecycle and Deprecation Policy",
      "durability": "DURABLE"
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      "claimId": "R7-C020",
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      "claim": "Current user-facing deprecation and removal policy.",
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      "specVersion": "Current policy",
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        "S020"
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        "S065"
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      "notes": "Feature Lifecycle and Deprecation Policy",
      "durability": "LIVE-CHECK REQUIRED"
    },
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      "claimId": "R7-C021",
      "packageClaimId": "C021",
      "claim": "Design rationale for eliminating the initialization handshake.",
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        "S021"
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      "sourceIds": [
        "S061"
      ],
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      "notes": "SEP-2575: Stateless MCP",
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    },
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      "claimId": "R7-C022",
      "packageClaimId": "C022",
      "claim": "Design rationale for removing protocol sessions and Mcp-Session-Id.",
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      "specVersion": "2026-07-28",
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        "S022"
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        "S316"
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      "notes": "SEP-2567: Sessionless MCP",
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    },
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      "claimId": "R7-C023",
      "packageClaimId": "C023",
      "claim": "Replacement for server-initiated request flows in the stateless era.",
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        "S023"
      ],
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        "S317"
      ],
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      "notes": "SEP-2322: Multi Round-Trip Requests",
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    },
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      "claimId": "R7-C024",
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      "claim": "Tasks moved from experimental core to an independently versioned extension.",
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      "specVersion": "Extension",
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        "S024"
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        "S137"
      ],
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      "notes": "Tasks Extension",
      "durability": "LIVE-CHECK REQUIRED"
    },
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      "claimId": "R7-C025",
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      "claim": "Formal extension lifecycle and compatibility framework.",
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      "specVersion": "Extensions",
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        "S025"
      ],
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        "S318"
      ],
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      "notes": "SEP-2133: Extensions Track",
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    },
    {
      "claimId": "R7-C026",
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      "claim": "Server package versions are distinct from protocol revisions; published versions are immutable.",
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      "specVersion": "Registry",
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        "S026"
      ],
      "sourceIds": [
        "S319"
      ],
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      "notes": "Registry Versioning",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C027",
      "packageClaimId": "C027",
      "claim": "Original stateful specification and launch-era capabilities.",
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      "specVersion": "2024-11-05",
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        "S027"
      ],
      "sourceIds": [
        "S249"
      ],
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      "notes": "Specification Overview — MCP 2024-11-05",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C028",
      "packageClaimId": "C028",
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      "specVersion": "2024-11-05",
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        "S028"
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      "sourceIds": [
        "S026"
      ],
      "confidence": "VERIFIED",
      "notes": "Lifecycle — MCP 2024-11-05",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C029",
      "packageClaimId": "C029",
      "claim": "Original stdio and HTTP+SSE transports.",
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      "specVersion": "2024-11-05",
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        "S029"
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      "sourceIds": [
        "S027"
      ],
      "confidence": "VERIFIED",
      "notes": "Transports — MCP 2024-11-05",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C030",
      "packageClaimId": "C030",
      "claim": "Original tool discovery and invocation.",
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      "specVersion": "2024-11-05",
      "packageSourceIds": [
        "S030"
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      "sourceIds": [
        "S028"
      ],
      "confidence": "VERIFIED",
      "notes": "Tools — MCP 2024-11-05",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C031",
      "packageClaimId": "C031",
      "claim": "Original resource listing, reading, templates and direct subscriptions.",
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      "specVersion": "2024-11-05",
      "packageSourceIds": [
        "S031"
      ],
      "sourceIds": [
        "S029"
      ],
      "confidence": "VERIFIED",
      "notes": "Resources — MCP 2024-11-05",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C032",
      "packageClaimId": "C032",
      "claim": "Original prompt discovery and retrieval.",
      "dateRange": "2024-11-05",
      "specVersion": "2024-11-05",
      "packageSourceIds": [
        "S032"
      ],
      "sourceIds": [
        "S030"
      ],
      "confidence": "VERIFIED",
      "notes": "Prompts — MCP 2024-11-05",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C033",
      "packageClaimId": "C033",
      "claim": "Authoritative March 2025 revision.",
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      "specVersion": "2025-03-26",
      "packageSourceIds": [
        "S033"
      ],
      "sourceIds": [
        "S035"
      ],
      "confidence": "VERIFIED",
      "notes": "MCP specification 2025-03-26",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C034",
      "packageClaimId": "C034",
      "claim": "OAuth framework, Streamable HTTP, JSON-RPC batching, tool annotations and audio.",
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      "specVersion": "2025-03-26",
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        "S034"
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        "S036"
      ],
      "confidence": "VERIFIED",
      "notes": "Changelog — MCP 2025-03-26",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C035",
      "packageClaimId": "C035",
      "claim": "Handshake-era lifecycle retained in March 2025.",
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      "specVersion": "2025-03-26",
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        "S035"
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        "S156"
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      "notes": "Lifecycle — MCP 2025-03-26",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C036",
      "packageClaimId": "C036",
      "claim": "Original Streamable HTTP and HTTP+SSE backward-compatibility path.",
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      "specVersion": "2025-03-26",
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        "S036"
      ],
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        "S038"
      ],
      "confidence": "VERIFIED",
      "notes": "Transports — MCP 2025-03-26",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C037",
      "packageClaimId": "C037",
      "claim": "First core OAuth authorization framework.",
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      "specVersion": "2025-03-26",
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        "S037"
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      "sourceIds": [
        "S037"
      ],
      "confidence": "VERIFIED",
      "notes": "Authorization — MCP 2025-03-26",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C038",
      "packageClaimId": "C038",
      "claim": "Authoritative June 2025 revision.",
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      "specVersion": "2025-06-18",
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        "S038"
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      "sourceIds": [
        "S042"
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      "confidence": "VERIFIED",
      "notes": "MCP specification 2025-06-18",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C039",
      "packageClaimId": "C039",
      "claim": "Batching removed, structured tool output, elicitation and OAuth hardening.",
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        "S039"
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        "S043"
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      "confidence": "VERIFIED",
      "notes": "Changelog — MCP 2025-06-18",
      "durability": "DURABLE"
    },
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      "claimId": "R7-C040",
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      "claim": "Handshake/session lifecycle retained in June 2025.",
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      "specVersion": "2025-06-18",
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        "S040"
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        "S159"
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      "confidence": "VERIFIED",
      "notes": "Lifecycle — MCP 2025-06-18",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C041",
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      "claim": "Sessionful Streamable HTTP and protocol-version header behavior.",
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      "specVersion": "2025-06-18",
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        "S041"
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        "S320"
      ],
      "confidence": "VERIFIED",
      "notes": "Transports — MCP 2025-06-18",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C042",
      "packageClaimId": "C042",
      "claim": "OAuth Resource Server classification, protected resource metadata and Resource Indicators.",
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      "specVersion": "2025-06-18",
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        "S042"
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        "S044"
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      "confidence": "VERIFIED",
      "notes": "Authorization — MCP 2025-06-18",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C043",
      "packageClaimId": "C043",
      "claim": "First elicitation capability and server-initiated interaction.",
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      "specVersion": "2025-06-18",
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        "S043"
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      "sourceIds": [
        "S046"
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      "confidence": "VERIFIED",
      "notes": "Elicitation — MCP 2025-06-18",
      "durability": "DURABLE"
    },
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      "claim": "Authoritative one-year revision.",
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        "S044"
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      "sourceIds": [
        "S048"
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      "confidence": "VERIFIED",
      "notes": "MCP specification 2025-11-25",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C045",
      "packageClaimId": "C045",
      "claim": "OIDC discovery, icons, CIMD, richer elicitation and experimental Tasks.",
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        "S045"
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        "S049"
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      "notes": "Changelog — MCP 2025-11-25",
      "durability": "DURABLE"
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        "S046"
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        "S160"
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      "notes": "Lifecycle — MCP 2025-11-25",
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      "claim": "Last released sessionful Streamable HTTP before 2026.",
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        "S047"
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        "S321"
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      "notes": "Transports — MCP 2025-11-25",
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      "claimId": "R7-C048",
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      "claim": "OIDC discovery, client metadata documents and incremental authorization.",
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      "specVersion": "2025-11-25",
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        "S048"
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        "S187"
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      "notes": "Authorization — MCP 2025-11-25",
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        "S049"
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        "S050"
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      "confidence": "VERIFIED",
      "notes": "Tasks — MCP 2025-11-25",
      "durability": "DURABLE"
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        "durability": "LIVE-CHECK REQUIRED"
      },
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    {
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    },
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    },
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        "S323"
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
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      "packageClaimId": "C058",
      "claim": "Stable Python v2 publication on July 28, 2026.",
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        "S058"
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        "S324"
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      "confidence": "VERIFIED",
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      "claim": "Exact Go SDK-to-protocol compatibility table.",
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        "S059"
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        "S325"
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C060",
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      "claim": "v1.7.0 adoption of 2026-07-28 and backward support.",
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      "specVersion": "Go SDK",
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        "S060"
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        "S326"
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C061",
      "packageClaimId": "C061",
      "claim": "Official C# SDK status and release documentation.",
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        "S061"
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      "sourceIds": [
        "S078"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "C# SDK repository",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C062",
      "packageClaimId": "C062",
      "claim": "Current C# SDK implementation documentation.",
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        "S062"
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      "sourceIds": [
        "S327"
      ],
      "confidence": "STRONGLY_SUPPORTED",
      "notes": "C# SDK documentation",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C063",
      "packageClaimId": "C063",
      "claim": "Java SDK 2.0 release chronology and target revision.",
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        "S063"
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        "S328"
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      "confidence": "VERIFIED",
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C064",
      "packageClaimId": "C064",
      "claim": "Current implementation gap for server/discover and 2026 revision.",
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        "S064"
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        "S329"
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      "confidence": "STRONGLY_SUPPORTED",
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C065",
      "packageClaimId": "C065",
      "claim": "rmcp 3.0 support for 2026-07-28 and compatibility notes.",
      "dateRange": "2026-07-28",
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        "S065"
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        "S330"
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      "confidence": "VERIFIED",
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C066",
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      "claim": "All five revisions, auto probing and legacy fallback.",
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      "specVersion": "Ruby SDK",
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        "S066"
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        "S331"
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C067",
      "packageClaimId": "C067",
      "claim": "Ruby stable release and then-current Tier 2 status.",
      "dateRange": "2026-07-27",
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        "S084"
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      "packageClaimId": "C068",
      "claim": "Evidence of current support claims while official tier remained Tier 2.",
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        "S068"
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      "sourceIds": [
        "S332"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Ruby SDK Tier 1 assessment request",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C069",
      "packageClaimId": "C069",
      "claim": "Dual-era behavior documented by PHP SDK.",
      "dateRange": "2026-08-26",
      "specVersion": "PHP SDK",
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        "S069"
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      "sourceIds": [
        "S333"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "PHP SDK Protocol Versions",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C070",
      "packageClaimId": "C070",
      "claim": "Current Tier 3 assessment and limitations.",
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      "specVersion": "PHP SDK",
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        "S070"
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        "S334"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "PHP SDK Tier Status",
      "durability": "LIVE-CHECK REQUIRED"
    },
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      "claimId": "R7-C071",
      "packageClaimId": "C071",
      "claim": "Current official Swift SDK development status.",
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      "confidence": "STRONGLY_SUPPORTED",
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C072",
      "packageClaimId": "C072",
      "claim": "Current official Kotlin SDK development status.",
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        "S072"
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        "S080"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Kotlin SDK repository",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C073",
      "packageClaimId": "C073",
      "claim": "Anthropic MCP host/product overview; exact wire revision may not be stated.",
      "dateRange": "2026-08-26",
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        "S145"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Model Context Protocol documentation",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C074",
      "packageClaimId": "C074",
      "claim": "Claude Code local/remote MCP support and server mode.",
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        "S259"
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      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C075",
      "packageClaimId": "C075",
      "claim": "ChatGPT remote MCP support; exact protocol revision not necessarily disclosed.",
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        "S075"
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        "S140"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Developer Mode and Full MCP Connectors in ChatGPT",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C076",
      "packageClaimId": "C076",
      "claim": "Client support for hosted MCP, Streamable HTTP, stdio and legacy SSE.",
      "dateRange": "2026-08-26",
      "specVersion": "Current product state",
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        "S076"
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        "S090"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "OpenAI Agents SDK — MCP",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C077",
      "packageClaimId": "C077",
      "claim": "VS Code local/remote server support and capability interfaces.",
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        "S077"
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        "S141"
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      "notes": "Use MCP Servers in VS Code",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
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      "packageClaimId": "C078",
      "claim": "Coding-agent MCP feature and capability limitations.",
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        "S265"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "MCP and GitHub Copilot Coding Agent",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C079",
      "packageClaimId": "C079",
      "claim": "Cursor MCP host/client behavior; exact wire revision may not be stated.",
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      "specVersion": "Current product state",
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        "S079"
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        "S269"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Cursor MCP documentation",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C080",
      "packageClaimId": "C080",
      "claim": "Gemini CLI MCP integration and capability support.",
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        "S144"
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      "notes": "Gemini CLI MCP Server Integration",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C081",
      "packageClaimId": "C081",
      "claim": "JetBrains host transports and capability support.",
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        "S081"
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        "S274"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Model Context Protocol in JetBrains AI Assistant",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C082",
      "packageClaimId": "C082",
      "claim": "Zed MCP host/client behavior.",
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        "S082"
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      "sourceIds": [
        "S284"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "MCP Servers in Zed",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C083",
      "packageClaimId": "C083",
      "claim": "Inspector support for legacy and modern protocol eras.",
      "dateRange": "2026-08-26",
      "specVersion": "Inspector v2",
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        "S083"
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        "S297"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "MCP Inspector",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C084",
      "packageClaimId": "C084",
      "claim": "Underlying request, response, notification and error model.",
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        "S084"
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        "S001"
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      "confidence": "VERIFIED",
      "notes": "JSON-RPC 2.0 Specification",
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    },
    {
      "claimId": "R7-C085",
      "packageClaimId": "C085",
      "claim": "Contrast between SemVer software releases and MCP date-based protocol revisions.",
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        "S085"
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        "S335"
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    {
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      "claim": "Current roadmap and retrospective on the July revision.",
      "dateRange": "2026-08-22",
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        "S086"
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      "sourceIds": [
        "S064"
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      "confidence": "STRONGLY_SUPPORTED",
      "notes": "MCP Roadmap",
      "durability": "LIVE-CHECK REQUIRED"
    },
    {
      "claimId": "R7-C087",
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      "claim": "The official specification releases page records stable and release-candidate tags, including a pre-launch 2024-10-07 tag outside this package's five-principal-revision comparison matrix.",
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        "S336"
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      "durability": "LIVE-CHECK REQUIRED",
      "packageSnapshot": {
        "claim": "Canonical release tags, RCs, stable dates and release notes.",
        "notes": "Specification releases",
        "durability": "LIVE-CHECK REQUIRED"
      },
      "editorialCorrection": "Qualified the five-principal-revision scope after checking the official releases page, which also contains a 2024-10-07 pre-launch tag."
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    {
      "claimId": "R7-C088",
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      "claim": "MCP 2024-11-05 belongs to the Handshake era and has lifecycle: initialize → initialize result → notifications/initialized.",
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        "S032"
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        "S249",
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        "S029",
        "S030"
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      "confidence": "VERIFIED",
      "notes": "Version matrix synthesis",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C089",
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      "claim": "MCP 2025-03-26 belongs to the Handshake era and has lifecycle: initialize handshake retained.",
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        "S037"
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      "notes": "Version matrix synthesis",
      "durability": "DURABLE"
    },
    {
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        "S042",
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        "S046"
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      "confidence": "VERIFIED",
      "notes": "Version matrix synthesis",
      "durability": "DURABLE"
    },
    {
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        "S336"
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      "notes": "Version matrix synthesis",
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    {
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      "claim": "MCP 2026-07-28 belongs to the Modern/stateless core era and has lifecycle: Optional server/discover; self-describing requests; no initialize.",
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        "S314"
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      "confidence": "VERIFIED",
      "notes": "Version matrix synthesis",
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    },
    {
      "claimId": "R7-C093",
      "packageClaimId": "C093",
      "claim": "Streamable HTTP replaced HTTP+SSE as the preferred remote transport. Compatibility consequence: Clients/servers using only HTTP+SSE need compatibility support or migration.",
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        "S036",
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      "notes": "Breaking-change register",
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      "packageClaimId": "C094",
      "claim": "Core OAuth authorization framework entered MCP. Compatibility consequence: Remote implementations acquired new roles and conformance requirements.",
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        "S036",
        "S037"
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      "claimId": "R7-C095",
      "packageClaimId": "C095",
      "claim": "Batching was added. Compatibility consequence: Implementations could send/accept arrays of messages in this revision.",
      "dateRange": "2025-03-26",
      "specVersion": "2025-03-26",
      "packageSourceIds": [
        "S034"
      ],
      "sourceIds": [
        "S036"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C096",
      "packageClaimId": "C096",
      "claim": "Tool annotations were added. Compatibility consequence: Hosts gained hints, not guarantees, affecting UI/policy.",
      "dateRange": "2025-03-26",
      "specVersion": "2025-03-26",
      "packageSourceIds": [
        "S034"
      ],
      "sourceIds": [
        "S036"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C097",
      "packageClaimId": "C097",
      "claim": "Batching was removed one revision after introduction. Compatibility consequence: March-only batching code must be disabled for June and later.",
      "dateRange": "2025-06-18",
      "specVersion": "2025-06-18",
      "packageSourceIds": [
        "S039"
      ],
      "sourceIds": [
        "S043"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C098",
      "packageClaimId": "C098",
      "claim": "Structured tool output and outputSchema were added. Compatibility consequence: Clients may validate/render structuredContent; older clients ignore or lack it.",
      "dateRange": "2025-06-18",
      "specVersion": "2025-06-18",
      "packageSourceIds": [
        "S039"
      ],
      "sourceIds": [
        "S043"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C099",
      "packageClaimId": "C099",
      "claim": "Elicitation was added as a server-initiated request. Compatibility consequence: Clients without elicitation remain partially compatible.",
      "dateRange": "2025-06-18",
      "specVersion": "2025-06-18",
      "packageSourceIds": [
        "S039",
        "S043"
      ],
      "sourceIds": [
        "S043",
        "S046"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C100",
      "packageClaimId": "C100",
      "claim": "Servers formally treated as OAuth resource servers with protected-resource metadata and Resource Indicators. Compatibility consequence: OAuth implementations required audience/resource binding changes.",
      "dateRange": "2025-06-18",
      "specVersion": "2025-06-18",
      "packageSourceIds": [
        "S039",
        "S042"
      ],
      "sourceIds": [
        "S043",
        "S044"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C101",
      "packageClaimId": "C101",
      "claim": "MCP-Protocol-Version became material to HTTP requests. Compatibility consequence: Hand-written clients must supply version metadata correctly.",
      "dateRange": "2025-06-18",
      "specVersion": "2025-06-18",
      "packageSourceIds": [
        "S039",
        "S041"
      ],
      "sourceIds": [
        "S043",
        "S320"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C102",
      "packageClaimId": "C102",
      "claim": "OIDC discovery and Client ID Metadata Documents expanded discovery/registration. Compatibility consequence: Client identity and authorization-server binding changed.",
      "dateRange": "2025-11-25",
      "specVersion": "2025-11-25",
      "packageSourceIds": [
        "S045",
        "S048"
      ],
      "sourceIds": [
        "S049",
        "S187"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C103",
      "packageClaimId": "C103",
      "claim": "Experimental Tasks entered the core specification. Compatibility consequence: Implementations could opt into a provisional long-running operation model.",
      "dateRange": "2025-11-25",
      "specVersion": "2025-11-25",
      "packageSourceIds": [
        "S045",
        "S049"
      ],
      "sourceIds": [
        "S049",
        "S050"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C104",
      "packageClaimId": "C104",
      "claim": "Icons and JSON Schema 2020-12 default were added or clarified. Compatibility consequence: Metadata and validation behavior changed.",
      "dateRange": "2025-11-25",
      "specVersion": "2025-11-25",
      "packageSourceIds": [
        "S045"
      ],
      "sourceIds": [
        "S049"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C105",
      "packageClaimId": "C105",
      "claim": "initialize was removed for the modern era. Compatibility consequence: Modern clients cannot depend on a startup negotiation request.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S004"
      ],
      "sourceIds": [
        "S055",
        "S056"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C106",
      "packageClaimId": "C106",
      "claim": "notifications/initialized was removed. Compatibility consequence: No initialization-complete notification exists in modern flows.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002"
      ],
      "sourceIds": [
        "S055"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C107",
      "packageClaimId": "C107",
      "claim": "Protocol-level sessions and Mcp-Session-Id were removed. Compatibility consequence: Servers must not hide correctness-critical state in a protocol session.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S021",
        "S022"
      ],
      "sourceIds": [
        "S055",
        "S061",
        "S316"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C108",
      "packageClaimId": "C108",
      "claim": "Protocol version, client identity and capabilities became request-scoped metadata. Compatibility consequence: Each request must be independently interpretable.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S004"
      ],
      "sourceIds": [
        "S055",
        "S056"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C109",
      "packageClaimId": "C109",
      "claim": "server/discover replaced initialize-based up-front server advertisement. Compatibility consequence: Clients need probing/pinning/fallback logic for cross-era operation.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S005"
      ],
      "sourceIds": [
        "S055",
        "S127"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C110",
      "packageClaimId": "C110",
      "claim": "Server-initiated requests were replaced by Multi Round-Trip Requests. Compatibility consequence: Sampling/elicitation-style workflows migrate to input_required and retry.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S023"
      ],
      "sourceIds": [
        "S055",
        "S317"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C111",
      "packageClaimId": "C111",
      "claim": "Result types distinguish complete from input_required. Compatibility consequence: Old result parsers may fail or treat new fields incorrectly.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S006"
      ],
      "sourceIds": [
        "S055",
        "S130"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C112",
      "packageClaimId": "C112",
      "claim": "resources/subscribe and unsolicited change notifications were replaced by subscriptions/listen streams. Compatibility consequence: Clients must explicitly request relevant event streams.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S012",
        "S054",
        "S057"
      ],
      "sourceIds": [
        "S055",
        "S124",
        "S168",
        "S323"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C113",
      "packageClaimId": "C113",
      "claim": "The standalone GET event stream and earlier resumability/redelivery model were removed. Compatibility consequence: Legacy SSE stream assumptions no longer apply.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S009",
        "S054"
      ],
      "sourceIds": [
        "S055",
        "S131",
        "S168"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C114",
      "packageClaimId": "C114",
      "claim": "Closing the request SSE stream became the HTTP cancellation signal. Compatibility consequence: Modern HTTP clients should not assume POST notifications/cancelled.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S009",
        "S054"
      ],
      "sourceIds": [
        "S131",
        "S168"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C115",
      "packageClaimId": "C115",
      "claim": "Mcp-Method, Mcp-Name and selected mirrored parameter headers were added. Compatibility consequence: Gateways can route/policy on headers; clients and servers must validate consistency.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S009",
        "S054"
      ],
      "sourceIds": [
        "S055",
        "S131",
        "S168"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C116",
      "packageClaimId": "C116",
      "claim": "Cacheable list/read results require ttlMs and cacheScope. Compatibility consequence: Clients need cache keys scoped by authorization context.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S011",
        "S012",
        "S054"
      ],
      "sourceIds": [
        "S055",
        "S123",
        "S124",
        "S168"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C117",
      "packageClaimId": "C117",
      "claim": "Experimental core Tasks moved to an official extension. Compatibility consequence: 2025 task wire types become legacy/deprecated vocabulary.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S024",
        "S054"
      ],
      "sourceIds": [
        "S055",
        "S137",
        "S168"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C118",
      "packageClaimId": "C118",
      "claim": "Roots, Sampling and Logging were deprecated. Compatibility consequence: They remain usable during the policy window but new designs should migrate.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S019",
        "S059"
      ],
      "sourceIds": [
        "S055",
        "S315",
        "S325"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C119",
      "packageClaimId": "C119",
      "claim": "HTTP+SSE was formally deprecated. Compatibility consequence: Legacy servers/clients need a migration path to Streamable HTTP.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S019"
      ],
      "sourceIds": [
        "S055",
        "S315"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C120",
      "packageClaimId": "C120",
      "claim": "Dynamic Client Registration was deprecated in favor of CIMD-oriented identification. Compatibility consequence: Clients/servers must plan registration migration.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S002",
        "S010"
      ],
      "sourceIds": [
        "S055",
        "S133"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C121",
      "packageClaimId": "C121",
      "claim": "Explicit application handles replaced implicit session state for multi-call workflows. Compatibility consequence: IDs must be authorized, unguessable where appropriate and passed in arguments.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S011",
        "S021",
        "S022"
      ],
      "sourceIds": [
        "S123",
        "S061",
        "S316"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C122",
      "packageClaimId": "C122",
      "claim": "Legacy ping and several session-scoped utility patterns are not part of the modern core. Compatibility consequence: SDKs may reject methods not valid for the negotiated era.",
      "dateRange": "2026-07-28",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S053",
        "S054",
        "S059"
      ],
      "sourceIds": [
        "S253",
        "S168",
        "S325"
      ],
      "confidence": "VERIFIED",
      "notes": "Breaking-change register",
      "durability": "DURABLE"
    },
    {
      "claimId": "R7-C123",
      "packageClaimId": "C123",
      "claim": "MCP compatibility has separable wire, lifecycle, transport, authorization, capability, extension and host-behavior dimensions.",
      "dateRange": "2024-2026",
      "specVersion": "All",
      "packageSourceIds": [
        "S003",
        "S004",
        "S007",
        "S010",
        "S050"
      ],
      "sourceIds": [
        "S121",
        "S056",
        "S057",
        "S133",
        "S073"
      ],
      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Analytical synthesis",
      "durability": "PERIODICALLY REVIEW"
    },
    {
      "claimId": "R7-C124",
      "packageClaimId": "C124",
      "claim": "A protocol version pin should fail rather than silently fall back when strict modern behavior is required.",
      "dateRange": "2026",
      "specVersion": "2026-07-28",
      "packageSourceIds": [
        "S053",
        "S056"
      ],
      "sourceIds": [
        "S253",
        "S166"
      ],
      "confidence": "VERIFIED",
      "notes": "Analytical synthesis",
      "durability": "PERIODICALLY REVIEW"
    },
    {
      "claimId": "R7-C125",
      "packageClaimId": "C125",
      "claim": "Legacy HTTP sessions can require sticky routing across multiple workers, while modern requests do not.",
      "dateRange": "2025-2026",
      "specVersion": "Cross-era",
      "packageSourceIds": [
        "S057"
      ],
      "sourceIds": [
        "S323"
      ],
      "confidence": "VERIFIED",
      "notes": "Analytical synthesis",
      "durability": "PERIODICALLY REVIEW"
    },
    {
      "claimId": "R7-C126",
      "packageClaimId": "C126",
      "claim": "A successful tools/list call does not prove resources, prompts, auth, subscriptions or extension compatibility.",
      "dateRange": "2024-2026",
      "specVersion": "All",
      "packageSourceIds": [
        "S003",
        "S050"
      ],
      "sourceIds": [
        "S121",
        "S073"
      ],
      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Analytical synthesis",
      "durability": "PERIODICALLY REVIEW"
    },
    {
      "claimId": "R7-C127",
      "packageClaimId": "C127",
      "claim": "Current product documentation often describes features without naming one canonical protocol revision.",
      "dateRange": "2026",
      "specVersion": "Current product state",
      "packageSourceIds": [
        "S073",
        "S075",
        "S077",
        "S079",
        "S080",
        "S081",
        "S082"
      ],
      "sourceIds": [
        "S145",
        "S140",
        "S141",
        "S269",
        "S144",
        "S274",
        "S284"
      ],
      "confidence": "STRONGLY_SUPPORTED",
      "notes": "Analytical synthesis",
      "durability": "PERIODICALLY REVIEW"
    }
  ]
}