Compatibility
The rule
Section titled “The rule”Protocol version decides compatibility. Package version numbers do not need to match across SDKs or the gateway.
A host speaking protocol 1.x works with a gateway speaking protocol 1.y, as long as the major version is the same. The tesseron/hello handshake negotiates minor differences. A newer minor can add fields, and an older peer can ignore fields it does not know.
Protocol support
Section titled “Protocol support”| Protocol version | Packages that speak it |
|---|---|
1.2.0 | @tesseron/core, @tesseron/web, @tesseron/server, @tesseron/react, @tesseron/svelte, @tesseron/vue, @tesseron/vite, and @tesseron/mcp >=2.10.0 |
1.2.0 | tesseron (Python) >=0.1.0. Published on PyPI. |
1.2.0 | tesseron (Rust) 0.1.x. Published on crates.io. |
1.2.0 | tesseron::tesseron (C++) >=0.1.0. Source-only, built through CMake FetchContent. |
The table starts at 1.2.0. The history checked for this page does not prove package boundaries for earlier protocol versions.
The Python and Rust SDKs carry their own versions and move on their own. They speak the same protocol, which is the only thing that has to match. C++ releases use the same rule and get rows here as they land.
The C++ host does not mint its own claim code and does not speak a unix domain socket, so it skips the bind/* fixtures and uds/file-mode and passes every other fixture in the suite. See C++ conformance.
TypeScript package versions
Section titled “TypeScript package versions”The seven TypeScript SDK packages (core, web, server, react, svelte, vue, and vite) are one fixed release group in tesseron-typescript. Install them at the same version. The hub packages @tesseron/mcp, @tesseron/docs-mcp, and @tesseron/conformance release independently. Gateway compatibility follows the protocol version rule above.
When the handshake fails
Section titled “When the handshake fails”A host and gateway with different protocol majors get this JSON-RPC error from the gateway:
Gateway speaks protocol 1.2.0; SDK sent 2.0.0. Major version mismatch. See https://eigenwise.github.io/tesseron/protocol/compatibility/Use a host and gateway that speak the same protocol major.
A legacy gateway that dials a host-minted WebSocket session without a bind subprotocol gets HTTP/1.1 426 Upgrade Required with this response body:
This Tesseron host requires a v1.2-compatible gateway (tesseron-bind subprotocol). Upgrade @tesseron/mcp to >= 2.4.0.Upgrade @tesseron/mcp to >=2.4.0.