The client currently implements the 2025-11-25 wire protocol. The 2026-07-28 revision is a structurally different protocol, not a version bump:
- the
initialize/notifications/initialized handshake is removed — server/discover replaces it, and every request carries its protocol version and capabilities in _meta
Mcp-Session-Id is gone from the Streamable HTTP transport- the standalone GET listening stream is replaced by
subscriptions/listen
- server-initiated requests are gone (MRTR pattern instead), and every result carries
resultType
So supporting it means a second client implementation behind the same McpTestClient interface, plus assertions for the new surfaces (server/discover correctness, resultType presence, CacheableResult fields on list results).
Current position: the JVM servers this toolkit targets (official java-sdk / Spring AI based) still negotiate 2025-11-25 or earlier — java-sdk 2.0.1's ProtocolVersions stops at 2025-11-25. Quarkus shipped 2026-07-28 support in quarkus-mcp-server 2.0.0.CR2, but Quarkus servers have their own in-process test DSL (McpAssured).
Trigger to start: java-sdk or Spring AI shipping (or announcing) 2026-07-28 support. Until then this stays open for design input.
If you need this sooner — e.g. you're building a stateless server on the JVM without Quarkus — comment here. Real demand moves this up the list.
The client currently implements the 2025-11-25 wire protocol. The 2026-07-28 revision is a structurally different protocol, not a version bump:
initialize/notifications/initializedhandshake is removed —server/discoverreplaces it, and every request carries its protocol version and capabilities in_metaMcp-Session-Idis gone from the Streamable HTTP transportsubscriptions/listenresultTypeSo supporting it means a second client implementation behind the same
McpTestClientinterface, plus assertions for the new surfaces (server/discovercorrectness,resultTypepresence,CacheableResultfields on list results).Current position: the JVM servers this toolkit targets (official java-sdk / Spring AI based) still negotiate 2025-11-25 or earlier — java-sdk 2.0.1's
ProtocolVersionsstops at 2025-11-25. Quarkus shipped 2026-07-28 support inquarkus-mcp-server2.0.0.CR2, but Quarkus servers have their own in-process test DSL (McpAssured).Trigger to start: java-sdk or Spring AI shipping (or announcing) 2026-07-28 support. Until then this stays open for design input.
If you need this sooner — e.g. you're building a stateless server on the JVM without Quarkus — comment here. Real demand moves this up the list.