tachyonmcp/tachyon

Model Context Protocol. It implements MCP 2025-11-25 and
2026-07-28 over Streamable HTTP and passes the official conformance suites for both versions.
Build servers with synchronous Java handlers or a coroutine-first Kotlin DSL. Tachyon runs
blocking handlers on virtual threads, keeps them off the Netty event loop, and requires no
application framework.
Why Tachyon?
- **Simple handlers** -- write blocking Java code or suspending Kotlin code without reactive
pipelines or manual thread pools.
- **Stable application API** -- protocol-version mappers isolate handlers from wire-format changes.
- **Java annotations support** -- adapt existing mcp-java, LangChain4j, or Spring AI annotated services into Tachyon MCP servers.
- **Stateless by default** -- opt into sessions only when you need resumable SSE, event replay, and
TTL cleanup.
- **Production transport** -- Netty backpressure, graceful shutdown, DNS-rebinding protection,
CORS, and native transport auto-detection (io_uring → epoll → kqueue → NIO).
- **Built-in OpenTelemetry** -- register tachyon-opentelemetry's listener for MCP
semantic-convention spans and metrics, with an opt-in policy for payload capture.
Quickstart
Import the BOM once to pin the version, then add the core dependency:
Create and start a server:
See the quickstart for Java and Kotlin examples plus a curl test.
Implemented features
| Area | Support |
|---|---|
| **MCP surface** | Tools, resources and templates, prompts, completions, logging, sampling, form/URL elicitation, cancellation, subscriptions, pagination, and progress notifications |
| **Annotations** | Optional adapters for mcp-java, LangChain4j, and Spring AI, mapped onto Tachyon's standard registries |
| **Tasks** | Full tasks/* lifecycle, state validation, status notifications, retention, and TasksExtension for SEP-2663, with SEP-1686 compatibility for MCP 2025-11-25 clients |
| **MCP Apps** | AppsExtension implements the SEP-1865 draft: ui:// HTML views with _meta.ui CSP and permissions, tool-to-view linkage, and io.modelcontextprotocol/ui advertisement |
| **Agent Skills** | SkillsExtension implements the SEP-2640 draft: filesystem/classpath registries, skill:// resources, skills/list, skills/get, and directory reads |
| **Extensions** | SEP-2133 negotiation, custom JSON-RPC methods, capability advertisement, and extension-gated features |
| **Runtime** | Stateless or resumable sessions, Last-Event-ID replay, pluggable stores, virtual-thread handlers, request timeouts, and graceful draining |
| **Observability** | OpenTelemetry spans and metrics via tachyon-opentelemetry, following the MCP semantic conventions, plus an opt-in payload capture policy -- see docs |
| **Java and Kotlin** | Independent sync/async Java contracts and a coroutine-first Kotlin DSL |
| **Testing** | Official conformance suites plus a testkit for dynamic servers and fluent JSON-RPC assertions |