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fix!: omit resultType for legacy protocol sessions (#1038)

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Dale Seo 2026-07-24 10:22:20 -04:00 • committed by GitHub
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2 changed files with 438 additions and 109 deletions
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82
crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema.json
View file

@ -199,13 +199,15 @@
]
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"structuredContent": {
"description": "An optional JSON object that represents the structured result of the tool call"
@ -326,13 +328,15 @@
"$ref": "#/definitions/CompletionInfo"
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
}
},
"required": [
@ -1140,13 +1144,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
}
},
"required": [
@ -1783,13 +1789,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -1842,13 +1850,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -1901,13 +1911,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -1959,13 +1971,15 @@
]
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"tools": {
"type": "array",
@ -2581,13 +2595,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -2948,7 +2964,7 @@
}
},
"ResultType": {
"description": "Indicates the type of a result object, allowing the client to\ndetermine how to parse the response.\n\nThe spec defines this as an open string (`\"complete\" | \"input_required\" | string`),\nso unknown values are preserved rather than rejected. Servers implementing this\nprotocol version MUST include `resultType` in every result. For backward\ncompatibility, clients MUST treat an absent field as `\"complete\"`.",
"description": "Indicates the type of a result object, allowing the client to\ndetermine how to parse the response.\n\nThe spec defines this as an open string (`\"complete\" | \"input_required\" | string`),\nso unknown values are preserved rather than rejected. Servers implementing this\nprotocol version MUST include `resultType` in every result. For backward\ncompatibility, clients MUST treat an absent field as `\"complete\"`.\n\nOrdinary results model the field as `Option<ResultType>`: `None` means the\nfield is absent on the wire. Constructors default to `Some(COMPLETE)`, and\nthe server handler strips the `\"complete\"` discriminator before responding\nto peers that negotiated a protocol version older than `2026-07-28`, so\nlegacy sessions keep their historical wire shape (see\n[`ServerResult::strip_result_type_for_legacy_peer`]).",
"type": "string"
},
"Role": {

82
crates/rmcp/tests/test_message_schema/server_json_rpc_message_schema_current.json
View file

@ -199,13 +199,15 @@
]
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"structuredContent": {
"description": "An optional JSON object that represents the structured result of the tool call"
@ -326,13 +328,15 @@
"$ref": "#/definitions/CompletionInfo"
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
}
},
"required": [
@ -1140,13 +1144,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
}
},
"required": [
@ -1783,13 +1789,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -1842,13 +1850,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -1901,13 +1911,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -1959,13 +1971,15 @@
]
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"tools": {
"type": "array",
@ -2581,13 +2595,15 @@
}
},
"resultType": {
"description": "Result type discriminator. Absent values deserialize as `\"complete\"`.",
"allOf": [
"description": "Result type discriminator (SEP-2322). Required by the [spec schema]\nfor servers implementing protocol version `2026-07-28`, but optional\nhere because this type also models results from older protocol\nversions, which do not carry the field: `None` means absent on the\nwire, and per the spec \"the client MUST treat the absent field as\n`\"complete\"`\". Constructors default to `Some(ResultType::COMPLETE)`;\nthe server handler clears the field when responding to peers that\nnegotiated an older version.\n\n[spec schema]: https://github.com/modelcontextprotocol/modelcontextprotocol/blob/5bed7b30527019e34ccb0eb474636651424501f6/schema/draft/schema.ts#L225-L234",
"anyOf": [
{
"$ref": "#/definitions/ResultType"
},
{
"type": "null"
}
],
"default": "complete"
]
},
"ttlMs": {
"description": "Time, in milliseconds, that this result may be treated as fresh (SEP-2549).\nRequired by spec version 2026-07-28, but optional here to maintain compatibility\nwith older spec versions.",
@ -2948,7 +2964,7 @@
}
},
"ResultType": {
"description": "Indicates the type of a result object, allowing the client to\ndetermine how to parse the response.\n\nThe spec defines this as an open string (`\"complete\" | \"input_required\" | string`),\nso unknown values are preserved rather than rejected. Servers implementing this\nprotocol version MUST include `resultType` in every result. For backward\ncompatibility, clients MUST treat an absent field as `\"complete\"`.",
"description": "Indicates the type of a result object, allowing the client to\ndetermine how to parse the response.\n\nThe spec defines this as an open string (`\"complete\" | \"input_required\" | string`),\nso unknown values are preserved rather than rejected. Servers implementing this\nprotocol version MUST include `resultType` in every result. For backward\ncompatibility, clients MUST treat an absent field as `\"complete\"`.\n\nOrdinary results model the field as `Option<ResultType>`: `None` means the\nfield is absent on the wire. Constructors default to `Some(COMPLETE)`, and\nthe server handler strips the `\"complete\"` discriminator before responding\nto peers that negotiated a protocol version older than `2026-07-28`, so\nlegacy sessions keep their historical wire shape (see\n[`ServerResult::strip_result_type_for_legacy_peer`]).",
"type": "string"
},
"Role": {