mcp: Implement retry on advised supportedVersions in UnsupportedProtocolVersion error#989
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guglielmo-san merged 4 commits intoJun 8, 2026
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…eiving UnsupportedProtocolVersionError
…ns in negotiation logic
…rtedProtocolVersionError
nahapetyan-serob
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Jun 8, 2026
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Conflicts: - mcp/server.go: union of the removed-in-new-protocol method list, keeping both branch additions (methodSubscribe, methodUnsubscribe) and main's addition (methodSetLevel) from PR #997. - mcp/client_test.go: kept all five branch-side TestInMemory_E2E_Discover* tests and main's new TestClientConnectDiscover_UnsupportedVersionNegotiation from PR #989 (retry on advised supportedVersions). Conflict was textual (adjacent functions) not semantic. Additional fix to make PR #989's negotiation test pass on this branch: exempt server/discover from the dispatcher's unsupported-version gate so that a probing client with an unsupported MCP-Protocol-Version can still reach the discover handler and learn the server's supportedVersions via the UnsupportedProtocolVersionError Data payload. Without this exemption, the gate at server.go:1561 short-circuited before the handler ran, leaving the client with no Supported list to negotiate from.
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Description
This PR introduces a retry mechanism for the discover method according to SEP-2575 (Issue #966)