Reimplement fast-time-server on the official rmcp SDK - #17
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Replace the hand-rolled JSON-RPC/session/protocol-negotiation layer with rmcp 3.0.0 (StreamableHttpService + tool macros). The server now runs dual-era only: legacy 2025-11-25 sessionful and modern 2026-07-28 stateless traffic are served concurrently by the SDK transport, and the --strict/--protocol flags are removed. All seven existing tools keep their names, schemas, and behavior, joined by a new verify-protocol tool that reports the protocol version active for the current request (per-request _meta on the modern era, negotiated session version on the legacy era). REST benchmark routes, /health, and /version are unchanged. rust-version bumps to 1.88 for the SDK MSRV. Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai> Signed-off-by: Jonathan Springer <jps@s390x.com>
README now documents the dual-era-only rmcp SDK server, the verify-protocol tool, and SSE streaming as it actually works on /mcp (replacing the stale /sse section and the --strict/--protocol flag docs). The locustfile SSE parser skips the SDK's empty priming data event on legacy responses. Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai> Signed-off-by: Jonathan Springer <jps@s390x.com>
Signed-off-by: Jonathan Springer <jps@s390x.com>
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Summary
Replaces fast-time-server's hand-rolled MCP protocol layer (~560 lines of manual JSON-RPC, session management, and dual-era version negotiation) with the official rmcp SDK 3.0.0, and adds a
verify-protocoltool that reports the protocol version active for the current request.What changed
StreamableHttpService(defaultlegacy_session_mode) serves legacy2025-11-25sessionful traffic and modern2026-07-28stateless traffic concurrently on/mcp.supported_protocol_versions()advertises exactly the two eras;initialize()/server/discoveruse SDK defaults.--strict/--protocolare gone — the server is dual-era only.verify-protocoltool: returns the active protocol version — from per-request_metaon the modern era (stateless), from the initialize-negotiated session version on the legacy era (session) — as text +structuredContentwith an auto-generatedoutputSchema.#[tool]macros and schemars-derived input schemas./api/echo,/api/time),/health,/versionunchanged.rust-version1.85 → 1.88 (SDK MSRV);uuid,async-stream,futures-utildropped./ssesection replaced with accurate SSE-on-/mcpdocs. locustfile SSE parser handles the SDK's priming event.Behavioral deltas (SDK defaults, documented in README)
text/event-stream) rather than plain JSON.initializeechoes known older protocol versions instead of forcing2025-11-25.Mcp-Method/Mcp-Nameheaders per SEP-2243.Verification
cargo fmt --check,cargo clippy --all-targets(0 warnings),cargo test— 30/30 pass.verify-protocol=2025-11-25/session; DELETE → 202. Modernserver/discoveradvertises exactly both eras; statelessverify-protocol=2026-07-28/stateless. REST endpoints verified.Note: MCP-path benchmarks should be re-baselined — the protocol path now carries SDK overhead;
/api/*REST numbers remain directly comparable.