Release v1.2.0

What's Changed

• fix(client): don't write transport and trace headers into the caller's header map by @serhiizghama in #1028
• fix(server): preserve typed JSON-RPC handler errors by @FlameHost10 in #1027
• fix(server): send empty arrays instead of null in results by @po-et in #989
• fix(server): reject missing client capabilities with invalid params by @po-et in #990
• fix(server): send URLElicitationRequiredError from handlers as -32042 by @po-et in #992
• fix(streamable-http): deliver notifications on modern subscriptions/listen streams by @po-et in #993
• fix(mcp): parse an input_required tool result that has no content by @po-et in #994
• fix(client): exclude tools with invalid x-mcp-header annotations by @po-et in #996
• test(client): remove the mock server's build cache after building it by @po-et in #998
• fix(server): report handlers that return no result as internal errors by @po-et in #999
• fix(sse): send a recovered panic's error with the request's id by @po-et in #1000
• fix(mcp): accept an Mcp-Param header sent with an empty value by @po-et in #1001
• fix(stdio): recover handler panics on the read loop by @po-et in #1002
• fix(oauth): reject authorization server metadata for another issuer by @po-et in #1004
• fix(oauth): authenticate at the token endpoint the way the server supports by @po-et in #1005
• fix(client): resume an SSE response stream the server ends early by @po-et in #1010
• fix(client): don't answer a server's request with null by @po-et in #1011
• fix(server): run a session's own tool when it is called as a task by @po-et in #1012
• fix(oauth): share one token refresh among concurrent callers by @po-et in #1013
• fix(oauth): discover the authorization server again after a failure by @po-et in #1014
• fix(oauth): send a token without a type as a bearer token by @po-et in #1015
• fix(client): cancel requests over stdio when their context ends by @po-et in #1016
• fix(sse): wait for room in the event queue instead of dropping a response by @po-et in #1017
• fix(client): support re-initializing after the server ends the session by @po-et in #1018
• fix(client): follow pagination cursors when listing tasks by @o-mid in #1020
• fix(mcp): omit empty completion context arguments by @hmdsefi in #1024
• perf(server): touch a known session without allocating by @pbednarcik in #1026
• fix: parse sampling content sent as an array by @hmdsefi in #1029
• fix(server): reject an unsupported MCP-Protocol-Version header by @hmdsefi in #1030
• fix(mcp): keep structuredContent on tool_result content by @hmdsefi in #1031
• fix(client): reject repeated pagination cursors on list APIs by @o-mid in #1033
• test(conformance): add official MCP server suite to CI by @mikamikasuki in #1038

New Contributors

• @po-et made their first contribution in #989
• @o-mid made their first contribution in #1020
• @hmdsefi made their first contribution in #1024
• @pbednarcik made their first contribution in #1026
• @mikamikasuki made their first contribution in #1038

Full Changelog: v1.1.1...v1.2.0