rmcp-v3.6.0

Added

• (client) cancel an abandoned tools/call, prompts/get or resources/read (#1344)
• (auth) add initial authorization scope selection (#1352)
• (transport) add non-blocking stdio_pipes transport (#1304)

Fixed

• (server) reject requests to 2026-07-28 clients (#1326)
• (streamable-http-server) look up tool schemas per request (#1349)
• (transport) follow same-origin 307/308 redirects in the default Streamable HTTP client (#1367)
• (streamable-http-server) answer a session-less non-initialize POST with 400 (#1377)
• (model) read a request id written in float form as that integer (#1346)
• (client) answer a server ping during the initialize handshake (#1366)
• (transport) accept nested x-mcp-header annotations (#1359)
• (streamable-http-client) handle error responses to initialize (#1361)
• (transport) bound the incoming line buffer in AsyncRwTransport (#1049)
• (model) reject malformed JSON-RPC messages with conflicting result and error fields (#1283) (#1287)
• ship LICENSE in rmcp and rmcp-macros crates (#1342)
• (streamable-http-server) release the session map lock before waiting on a session (#1323)
• (rmcp) gate client- and server-only helpers behind their features (#1329)
• cancel pending request tokens after transport EOF (#1333)
• (rmcp) import base64-only prompt content types under the feature (#1314)

Other

• combine AI issue triage with a maintainer rotation as the responsible reviewer (#1260)